The University of Arizona is a public research university located in Tucson, Arizona, United States. UA was the first university in the state of Arizona, founded in 1885 . The university includes the University of Arizona College of Medicine, which operates a medical center in Tucson, and a separate 4-year M.D. college in downtown Phoenix. As of the 2012-2013 calendar year, total enrollment was 40,223 students. The University of Arizona is governed by the Arizona Board of Regents. The mission of the University of Arizona is, "To discover, educate, serve, and inspire." Arizona is one of the elected members of the Association of American Universities and is the only representative from the state of Arizona to this group.Known as the Arizona Wildcats , the athletic teams are members of the Pacific-12 Conference in the NCAA. UA athletes have won national titles in several sports, most notably men's basketball, baseball, and softball. The official colors of the university and its athletic teams are Cardinal Red and Navy Blue. Wikipedia.
McCutcheon J.P.,University of Arizona
Current Opinion in Microbiology | Year: 2010
Bacterial genomes vary in size over two orders of magnitude. The Mycoplasma genitalium genome has historically defined the extreme small end of this spectrum, and has therefore heavily informed theoretical and experimental work aimed at determining the minimal gene content necessary to support cellular life. Recent genomic data from insect symbionts have revealed bacterial genomes that are incredibly small - two to four times smaller than M. genitalium - and these tiny genomes have raised questions about the limits of genome reduction and have blurred the once-clear distinction between autonomous cellular life and highly integrated organelle. New data from various systems with symbiotic bacterial or archaeal partners have begun to shed light on how these bacteria may function with such small gene sets, but major mechanistic questions remain. © 2009 Elsevier Ltd. All rights reserved.
Skodol A.E.,University of Arizona
Annual Review of Clinical Psychology | Year: 2012
A substantive revision of the Diagnostic and Statistical Manual of Mental Disorders (DSM) last occurred in 1994; therefore, the mental health field should anticipate significant changes to the classification of mental disorders in the fifth edition. Since DSM-5 Work Groups have recently proposed revisions for the major diagnostic classes of mental disorders, an article on the current status of the personality disorders (PDs) is timely. This article reviews scientific principles that have influenced the development of proposed changes for the assessment and diagnosis of personality psychopathology in DSM-5, presents the proposed model as of the summer of 2011, summarizes rationales for the changes, and discusses critiques of the model. Scientific principles were articulated for DSM-5 more than a decade ago; their application to the process has not been straightforward, however. Work Group members have labored to improve the DSM-5 approach to personality and PDs to make the classification more valid and more clinically useful. The current model continues to be a work in progress. © Copyright ©2012 by Annual Reviews. All rights reserved.
Friese R.S.,University of Arizona
Nutrition in Clinical Practice | Year: 2012
The use of the "open abdomen" as a technique in the management of the complex surgical patient stems from the concept of damage control. Damage control principles underscore the importance of an abbreviated laparotomy focused on control of hemorrhage and gastrointestinal contamination in patients presenting with significant physiologic compromise. Definitive repair of injuries is postponed and the abdomen is temporarily "closed" using one of a number of different techniques. The ultimate goal is formal abdominal fascial closure within 48-72 hours of the initial laparotomy. Frequently, daily trips to the operating room are required for incremental closure of the abdominal fascia. However, in some cases, fascial closure is not possible secondary to ongoing visceral edema and loss of the peritoneal domain. In these cases, the patient is left with an "open abdomen" until skin grafting over the exposed peritoneal organs can be performed. Patients with an open abdomen have peritoneal contents exposed to the atmosphere and require a complex dressing to maintain fascial domain and provide protection to exposed organs. These patients are typically critically ill and managed in the intensive care unit early in the disease process. The open abdomen has become an important tool for the management of physiologically unstable patients requiring emergent abdominal surgical procedures. These patients present unique challenges to the critical care and nutrition support teams. Careful attention to fluid and electrolyte management, meticulous wound care, prevention of enteroatmospheric fistula, and individualized nutrition support therapy are essential to successful recovery in this patient population. © 2012 American Society for Parenteral and Enteral Nutrition.
Whitcomb M.E.,University of Arizona
Academic Medicine | Year: 2013
It is widely recognized that the United States is going to experience a serious shortage of physicians in the coming years unless the number of physicians completing residency training and entering practice is greatly increased. Members of the academic medicine community have approached this issue by calling on Congress to eliminate the cap that currently limits the number of residency positions that Medicare will support. Simply eliminating the cap, however, will not ensure an adequate supply of physicians. In this commentary the author argues that decreasing the length of training required in core clinical specialties will be required to effectively address the workforce shortage by allowing more residents to be trained in core specialties without greatly increasing the number of training programs and the aggregate amount that Medicare currently spends on graduate medical education.
Gehrels G.,University of Arizona
Annual Review of Earth and Planetary Sciences | Year: 2014
Detrital zircon geochronology is rapidly developing into an essential tool in Earth science research because of the widespread occurrence of zircon in sedimentary systems; the wide range of information that can be extracted from zircon crystals; the ability to determine ages with reasonable precision, accuracy, and efficiency; and the wide range of new ideas about how to use detrital zircon geochronologic information. The U-Pb system is particularly powerful because three chronometers are available (238U→ 206Pb, 235U→207Pb, and 232Th→208Pb), but challenges arise because of complexities from inheritance and Pb loss. Ages can be used to constrain the age of deposition of the host sediment, reconstruct provenance, characterize a sedimentary unit, and characterize many different aspects of source regions. Detrital zircon geochronology has an exciting future given the growth history recorded in individual crystals; the variety of detrital minerals that can provide complementary information; and the large number of geochemical, isotopic, and chronologic systems that can be applied to these minerals. © 2014 by Annual Reviews. All rights reserved.
Rains S.A.,University of Arizona
Journal of Health Communication | Year: 2014
Uncertainty management theory was applied in the present study to offer one theoretical explanation for how individuals use the World Wide Web to acquire health information and to help better understand the implications of the Web for information seeking. The diversity of information sources available on the Web and potential to exert some control over the depth and breadth of one's information-acquisition effort is argued to facilitate uncertainty management. A total of 538 respondents completed a questionnaire about their uncertainty related to cancer prevention and information-seeking behavior. Consistent with study predictions, use of the Web for information seeking interacted with respondents' desired level of uncertainty to predict their actual level of uncertainty about cancer prevention. The results offer evidence that respondents who used the Web to search for cancer information were better able than were respondents who did not seek information to achieve a level of uncertainty commensurate with the level of uncertainty they desired. © 2014 Taylor & Francis Group, LLC.
Raichlen D.A.,University of Arizona
Proceedings. Biological sciences / The Royal Society | Year: 2013
The hunting and gathering lifestyle adopted by human ancestors around 2 Ma required a large increase in aerobic activity. High levels of physical activity altered the shape of the human body, enabling access to new food resources (e.g. animal protein) in a changing environment. Recent experimental work provides strong evidence that both acute bouts of exercise and long-term exercise training increase the size of brain components and improve cognitive performance in humans and other taxa. However, to date, researchers have not explored the possibility that the increases in aerobic capacity and physical activity that occurred during human evolution directly influenced the human brain. Here, we hypothesize that proximate mechanisms linking physical activity and neurobiology in living species may help to explain changes in brain size and cognitive function during human evolution. We review evidence that selection acting on endurance increased baseline neurotrophin and growth factor signalling (compounds responsible for both brain growth and for metabolic regulation during exercise) in some mammals, which in turn led to increased overall brain growth and development. This hypothesis suggests that a significant portion of human neurobiology evolved due to selection acting on features unrelated to cognitive performance.
Moriniere L.,University of Arizona
Urban Studies | Year: 2012
Over the past 30 years, urbanisation has been a prominent phenomenon and various drivers have been proposed to explain it. Very few have suggested that the degradation of the rural environment was one of them. This paper explores the human-environment interface by focusing on the portrayal of these concepts within scholarly literature. A systematic literature review was conducted and 147 articles were examined to determine the direction of the link between the environment and human mobility, and if urbanisation was featured. The results demonstrate that equal attention is paid to both directions of the environment-mobility link. Of the articles reviewed, 40 per cent focus on urbanisation, but 93 per cent of those portray urbanisation as a forcing on the environment, rather than an impact of environmental degradation. The lack of support for environmentally influenced urbanisation can be explained by coupled system complexity, disciplinary research and the silence of those most likely to endure environmental change. Understanding these relationships is paramount to the promotion of adaptation without eroding resilience or further degrading environments. © 2011 Urban Studies Journal Limited.
Huxter V.M.,University of California at Berkeley |
Oliver T.A.A.,University of California at Berkeley |
Budker D.,University of Arizona |
Fleming G.R.,University of California at Berkeley
Nature Physics | Year: 2013
The optical and material properties of negatively charged nitrogen-vacancy (NV) centres in diamond make them attractive for applications ranging from quantum information to electromagnetic sensing. These properties are strongly dependent on the vibrational manifold associated with the centre, which determines phenomena associated with decoherence, relaxation and spin-orbit coupling. Despite its paramount importance in tuning these properties, the role of the vibrational bath and its effect on the electronic-state dynamics of NV centres in diamond is not fully understood. To elucidate the role of the bath, we present two-dimensional electronic spectroscopic studies of ensembles of negatively charged NV defect centres in diamond (NVD). We observe picosecond non-radiative relaxation within the phonon sideband and find that strongly coupled local modes dominate the vibrational bath. These findings provide a starting point for new insights into dephasing, spin addressing and relaxation in NVD with broad implications for magnetometry, quantum information, nanophotonics, sensing and ultrafast spectroscopy. © 2013 Macmillan Publishers Limited.
Armstrong E.P.,University of Arizona
Journal of Managed Care Pharmacy | Year: 2010
BACKGROUND: Vaccines have demonstrated cost-effectiveness in managed care through the prevention of disease. As new vaccines for previously untargeted conditions are developed, pharmacoeconomic modeling is becoming even more critical for the quantification of value in the health care industry. Two recently developed vaccines aimed at prevention of infection from human papillomavirus (HPV) types 16 and 18 have proven to be highly efficacious. HPV 16 and 18 are the 2 most common oncogenic strains of HPV and are responsible for 70% of cervical cancer cases worldwide. Persistent infection with an oncogenic HPV type is a known cause of cervical cancer. Therefore, prevention of cervical cancer via HPV vaccination may have a significant financial impact. OBJECTIVE: To qualitatively review existing mathematical models of the cost-effectiveness of prophylactic HPV vaccination, with an emphasis on the impact on managed care in the United States. METHODS: Mathematical models of the cost-effectiveness of HPV vaccination based on U.S. data were reviewed. A search of the PubMed database was conducted using the search terms "HPV," "vaccine," and "cost-effectiveness" for articles published before February 22, 2010. Studies employing mathematical models to estimate the cost-effectiveness of HPV vaccination in healthy subjects from the United States were included. Models based on data or populations from outside of the United States were excluded. Outcomes were measured with incremental cost-effectiveness ratios (ICERs), typically in units of quality-adjusted life expectancy (quality-adjusted life years [QALYs] gained). Most studies included in this review modeled vaccination of a cohort or population of females aged 12 years. Assessment of catch-up vaccination in females (through aged 24 to 26 years) was included in a couple of reports. One study examined vaccination in older females (aged 35, 40, and 45 years). Models typically compared a strategy of HPV vaccination with the current practice of cervical screening (sampling of cervical cells for disease detection) alone. RESULTS: 11 studies of cost-effectiveness modeling of HPV vaccination were included in this review. A direct quantitative comparison of model results is challenging due to the utilization of different model types as well as differences in variables selected within the same model type. Each model produced a range of cost-effectiveness ratios, dependent on variables included in sensitivity analyses and model assumptions. Sensitivity analyses revealed the lowest ICER to be $997 per QALY gained and the highest ICER to be $12,749,000 per QALY gained. This enormous range highlights the need to clarify what model assumptions are being made. The 2 studies that included modeling of catch-up vaccination scenarios in females older than age 12 years also produced a wide range of ICERs. One study, assuming 90% efficacy, 100% coverage, and lifelong immunity, modeled catch-up vaccination in all females aged 12 to 24 years and yielded an ICER of $4,666 per QALY. If the duration of protection was limited to 10 years, then costs increased to $21,121 per QALY. The other study modeling catch-up HPV vaccination assumed 100% efficacy, 75% coverage, and lifelong immunity. ICERs in this study for outcomes relating to cervical cancer ranged from $43,600 per QALY in the base model vaccinating only 12 year olds with no catch-up vaccination, to $152,700 in a model including catch-up vaccination through age 26 years. Although catch-up to age 21 years resulted in a cost of $120,400 per QALY, the ICER decreased to $101,300 per QALY if model outcomes related to prevention of genital warts were also included. The lone study modeling vaccination in women aged 35 to 45 years resulted in an ICER range of $116,950 to $272,350 per QALY when compared with annual and biennial cytological screening. Cost-effectiveness was defined as an ICER at or below $100,000 per QALY gained. All models of female adolescent vaccination were able to produce vaccination strategies that would be cost-effective according to this definition in addition to many strategies that would be cost-prohibitive. Variables influential in determining cost-effectiveness of HPV vaccination included the frequency of accompanying cervical screening, the age at which screening is initiated, vaccination efficacy, duration of vaccine protection, and the age range of females to be vaccinated. The actual effectiveness of HPV vaccination in the female population will also depend on levels of vaccine uptake or coverage and compliance in completing all vaccine doses. CONCLUSION: Clinical studies have shown HPV vaccination to be highly efficacious and potentially lifesaving if administered to females naïve or unexposed to vaccine HPV types. Modeling studies have also shown that HPV vaccination can be cost-effective with an ICER of $100,000 or less per QALY gained if administered to females aged 12 years in the context of cervical screening intervals typically greater than 1 year. Catch-up vaccination through 21 years of age increases the cost per QALY to more than $100,000. Until real-world coverage rates increase, cost-effectiveness modeling of HPV vaccination underestimates the actual cost per QALY. Copyright © 2010, Academy of Managed Care Pharmacy. All rights reserved.
Bastian N.,University of Cambridge |
Covey K.R.,Cornell University |
Covey K.R.,Harvard - Smithsonian Center for Astrophysics |
Meyer M.R.,ETH Zurich |
Meyer M.R.,University of Arizona
Annual Review of Astronomy and Astrophysics | Year: 2010
Whether the stellar initial mass function (IMF) is universal or is instead sensitive to environmental conditions is of critical importance: The IMF influences most observable properties of stellar populations and thus galaxies, and detecting variations in the IMF could provide deep insights into the star formation process. This review critically examines reports of IMF variations, with a view toward whether other explanations are sufficient given the evidence. Studies of the field, young clusters and associations, and old globular clusters suggest that the vast majority were drawn from a universal system IMF: a power law of Salpeter index (Γ = 1.35) above a few solar masses, and a log normal or shallower power law (Γ ̃ 0-0.25) for lower mass stars. The shape and universality of the substellar IMF is still under investigation. Observations of resolved stellar populations and the integrated properties of most galaxies are also consistent with a universal IMF, suggesting no gross variations over much of cosmic time. Indications of "nonstandard" IMFs in specific local and extragalactic environments clearly warrant further study. However, there is no clear evidence that the IMF varies strongly and systematically as a function of initial conditions after the first few generations of stars. © 2010 by Annual Reviews.
Melia F.,University of Arizona
Astronomical Journal | Year: 2014
Observations with WFC3/IR on the Hubble Space Telescope and the use of gravitational lensing techniques have facilitated the discovery of galaxies as far back as z ∼ 10-12, a truly remarkable achievement. However, this rapid emergence of high-z galaxies, barely ∼200 Myr after the transition from Population III star formation to Population II, appears to be in conflict with the standard view of how the early universe evolved. This problem has much in common with the better known (and probably related) premature appearance of supermassive black holes at z ≳ 6. It is difficult to understand how ∼109 M ⊙black holes could have appeared so quickly after the big bang without invoking non-standard accretion physics and the formation of massive seeds, neither of which is seen in the local universe. In earlier work, we showed that the appearance of high-z quasars could instead be understood more reasonably in the context of the R h = ct universe, which does not suffer from the same time compression issues as ΛCDM does at early epochs. Here, we build on that work by demonstrating that the evolutionary growth of primordial galaxies was consistent with the current view of how the first stars formed, but only with the timeline afforded by the R h = ct cosmology. We also show that the growth of high-z quasars was mutually consistent with that of the earliest galaxies, though it is not yet clear whether the former grew from 5-20 M ⊙ seeds created in Population III or Population II supernova explosions. © 2014. The American Astronomical Society. All rights reserved.
Zhang J.,University of Arizona
Molecular & cellular proteomics : MCP | Year: 2012
Nrf2 gene encodes a transcription factor that regulates the expression of a cluster of antioxidant and detoxification genes. Recent works from our laboratory indicate that oxidative stress causes rapid de novo synthesis of Nrf2 protein. We have found that 5' Untranslated Region (5'UTR) of Nrf2 allows the mRNA to undergo an Internal Ribosomal Entry Site (IRES) mediated protein translation. Using liquid chromatography tandem MS, we have discovered that La/SSB protein bound to Nrf2 5'UTR in response to oxidative stress. In vitro RNA binding and in vivo ribonucleoprotein immunoprecipitation showed H(2)O(2) dose and time dependent increases of La/SSB binding to Nrf2 5'UTR. La/SSB protein translocated from the nuclei to cytoplasm and distributed in the perinuclear space in cells treated with H(2)O(2). Isolation of ribosomal fractions indicated that oxidants caused an association of La/SSB with ribosomes. Physical interaction of La/SSB with representative proteins from the small or large subunits of ribosomes was found to increase in cells responding to H(2)O(2) treatment. Knocking down La/SSB gene with siRNA prevented Nrf2 protein elevation or Nrf2 5'UTR activation by oxidants. In contrast, overexpression of La/SSB gene was able to enhance Nrf2 5'UTR activation and Nrf2 protein increase. Our data suggest that oxidants cause nuclear export of La/SSB protein and subsequent association of La/SSB with Nrf2 5'UTR and ribosomes. These events contribute to de novo Nrf2 protein translation because of oxidative stress.
Pelletier J.D.,University of Arizona
Bulletin of the Geological Society of America | Year: 2010
Pediments are gently sloping, low-relief bedrock erosional surfaces at the bases of mountain ranges. Pediments tend to form more readily in arid climates and in weathering-resistant lithologies, but the processes responsible for pediment formation are still not widely understood after more than a century of debate. In this paper, I investigate the behavior of a coupled numerical model for the evolution of mountain ranges and their adjacent piedmonts that includes bedrock erosion in channels, soil production and erosion on hillslopes, and the flexural-isostatic response of the lithosphere to erosional unloading. For relatively small values of the flexural parameter, erosion of the mountain range leads to sufficient flexural-isostatic tilting of the adjacent piedmont that a suballuvial bedrock bench is exhumed to form an erosional surface on the piedmont. In addition, slope retreat at the mountain front and subsequent tilting of the abandoned surface can contribute to pediment formation by lengthening the pediment in the upslope direction. The rate of erosion on the piedmont must also be greater than or equal to the rate of soil production, thereby creating an erosional surface that has, at most, a thin veneer of soil or regolith. The rate of soil production depends primarily on climate and lithology, with lower soil production rates associated with more arid climates and more resistant lithologies. The model predictions are compared to morphometric analyses of pediments in the southwestern United States and to the detailed morphology of two classic pediments in southern Arizona. © 2010 Geological Society of America.
Celestini F.,CNRS Condensed Matter Physics Laboratory |
Frisch T.,CNRS Non-Linear Institute of Nice |
Pomeau Y.,University of Arizona
Physical Review Letters | Year: 2012
We put in evidence the unexpected behavior of Leidenfrost droplets at the later stage of their evaporation. We predict and observe that, below a critical size R l, the droplets spontaneously take off due to the breakdown of the lubrication regime. We establish the theoretical relation between the droplet radius and its elevation. We predict that the vapor layer thickness increases when the droplets become smaller. A satisfactory agreement is found between the model and the experimental results performed on droplets of water and of ethanol. © 2012 American Physical Society.
Zakharov V.E.,University of Arizona |
Zakharov V.E.,RAS Lebedev Physical Institute |
Gelash A.A.,Novosibirsk State University
Physical Review Letters | Year: 2013
We study the nonlinear stage of the modulation instability of a condensate in the framework of the focusing nonlinear Schrödinger equation (NLSE). We find a general N-solitonic solution of the focusing NLSE in the presence of a condensate by using the dressing method. We separate a special designated class of "regular solitonic solutions" that do not disturb phases of the condensate at infinity by coordinate. All regular solitonic solutions can be treated as localized perturbations of the condensate. We find an important class of "superregular solitonic solutions" which are small perturbations at a certain moment of time. They describe the nonlinear stage of the modulation instability of the condensate. © 2013 American Physical Society.
Stone J.,University of Arizona |
Moskowitz G.B.,Lehigh University
Medical Education | Year: 2011
Context Non-conscious stereotyping and prejudice contribute to racial and ethnic disparities in health care. Contemporary training in cultural competence is insufficient to reduce these problems because even educated, culturally sensitive, egalitarian individuals can activate and use their biases without being aware they are doing so. However, these problems can be reduced by workshops and learning modules that focus on the psychology of non-conscious bias. The Psychology of NON-Conscious Bias Research in social psychology shows that over time stereotypes and prejudices become invisible to those who rely on them. Automatic categorisation of an individual as a member of a social group can unconsciously trigger the thoughts (stereotypes) and feelings (prejudices) associated with that group, even if these reactions are explicitly denied and rejected. This implies that, when activated, implicit negative attitudes and stereotypes shape how medical professionals evaluate and interact with minority group patients. This creates differential diagnosis and treatment, makes minority group patients uncomfortable and discourages them from seeking or complying with treatment. Pitfalls in Cultural Competence Training Cultural competence training involves teaching students to use race and ethnicity to diagnose and treat minority group patients, but to avoid stereotyping them by over-generalising cultural knowledge to individuals. However, the Culturally and Linguistically Appropriate Services (CLAS) standards do not specify how these goals should be accomplished and psychological research shows that common approaches like stereotype suppression are ineffective for reducing non-conscious bias. To effectively address bias in health care, training in cultural competence should incorporate research on the psychology of non-conscious stereotyping and prejudice. Training in Implicit Bias Enhances Cultural Competence Workshops or other learning modules that help medical professionals learn about non-conscious processes can provide them with skills that reduce bias when they interact with minority group patients. Examples of such skills in action include automatically activating egalitarian goals, looking for common identities and counter-stereotypical information, and taking the perspective of the minority group patient. © Blackwell Publishing Ltd 2011.
Crescioni M.,University of Arizona
National health statistics reports | Year: 2010
OBJECTIVES: This report examines trends in health status and risk factors, health care utilization, and health care expenditures among older men in the United States. METHODS: The estimates in this report are based on data from the National Vital Statistics System, National Health Interview Survey, National Health and Nutrition Examination Survey, National Health Care Surveys, Medicare Current Beneficiary Survey, and Current Population Survey. Trends in death rates, prevalence of chronic conditions, risk factors, vaccinations, health care utilization, and expenditures are summarized. Major differences in these indicators are described for older men and women and by age, race, and Hispanic origin. RESULTS: The difference in life expectancy between older men and women has narrowed since 1980, but a gap remains. Older men have lower hypertension and cholesterol levels and exercise regularly at higher rates than older women; however, the rates of obesity and cigarette smoking are similar in older men and women. Although health status has improved for all racial and ethnic groups, racial and ethnic disparities remain for many indicators. Older men and women have similar rates of hospital admissions and visits to emergency departments and physician offices.
Rai V.,University of Texas at Austin |
Henry A.D.,University of Arizona
Nature Climate Change | Year: 2016
Strategies to mitigate global climate change should be grounded in a rigorous understanding of energy systems, particularly the factors that drive energy demand. Agent-based modelling (ABM) is a powerful tool for representing the complexities of energy demand, such as social interactions and spatial constraints. Unlike other approaches for modelling energy demand, ABM is not limited to studying perfectly rational agents or to abstracting micro details into system-level equations. Instead, ABM provides the ability to represent behaviours of energy consumers-such as individual households-using a range of theories, and to examine how the interaction of heterogeneous agents at the micro-level produces macro outcomes of importance to the global climate, such as the adoption of low-carbon behaviours and technologies over space and time. We provide an overview of ABM work in the area of consumer energy choices, with a focus on identifying specific ways in which ABM can improve understanding of both fundamental scientific and applied aspects of the demand side of energy to aid the design of better policies and programmes. Future research needs for improving the practice of ABM to better understand energy demand are also discussed. © 2016 Macmillan Publishers Limited.
Kunyansky L.,University of Arizona
Inverse Problems | Year: 2011
We present explicit filtration/backprojection-type formulae for the inversion of the spherical (circular) mean transform with the centers lying on the boundary of some polyhedra (or polygons, in 2D). The formulae are derived using the double-layer potentials for the wave equation, for domains with certain symmetries. The formulae are valid for a rectangle and certain triangles in 2D, and for a cuboid, certain right prisms and a certain pyramid in 3D. All the present inversion formulae yield exact reconstruction within the domain surrounded by the acquisition surface even in the presence of exterior sources. © 2011 IOP Publishing Ltd.
Borsook D.,Harvard University |
Hargreaves R.,Harvard University |
Bountra C.,University of Oxford |
Porreca F.,University of Arizona
Science Translational Medicine | Year: 2014
There is a critical need for effective new pharmacotherapies for pain. The paucity of new drugs successfully reaching the clinic calls for a reassessment of current analgesic drug discovery approaches. Many points early in the discovery process present significant hurdles, making it critical to exploit advances in pain neurobiology to increase the probability of success. In this review, we highlight approaches that are being pursued vigorously by the pain community for drug discovery, including innovative preclinical pain models, insights from genetics, mechanistic phenotyping of pain patients, development of biomarkers, and emerging insights into chronic pain as a disorder of both the periphery and the brain. Collaborative efforts between pharmaceutical, academic, and public entities to advance research in these areas promise to de-risk potential targets, stimulate investment, and speed evaluation and development of better pain therapies. © 2014, American Association for the Advancement of Science. All rights reserved.
Dickinson W.R.,University of Arizona
Quaternary Research (United States) | Year: 2013
Unlike most tropical Pacific islands, which lie along island arcs or hotspot chains, the Loyalty Islands between New Caledonia and Vanuatu owe their existence and morphology to the uplift of pre-existing atolls on the flexural forebulge of the New Hebrides Trench. The configuration and topography of each island is a function of distance from the crest of the uplifted forebulge. Both Maré and Lifou are fully emergent paleoatolls upon which ancient barrier reefs form highstanding annular ridges that enclose interior plateaus representing paleolagoon floors, whereas the partially emergent Ouvea paleoatoll rim flanks a drowned remnant lagoon. Emergent paleoshoreline features exposed by island uplift include paleoreef flats constructed as ancient fringing reefs built to past low tide levels and emergent tidal notches incised at past high tide levels. Present paleoshoreline elevations record uplift rates of the islands since last-interglacial and mid-Holocene highstands in global and regional sea levels, respectively, and paleoreef stratigraphy reflects net Quaternary island emergence. The empirical uplift rates vary in harmony with theoretical uplift rates inferred from the different positions of the islands in transit across the trench forebulge at the trench subduction rate. The Loyalty Islands provide a case study of island environments controlled primarily by neotectonics. © 2013 University of Washington.
Baker V.R.,University of Arizona
Planetary and Space Science | Year: 2014
Analogical reasoning is critical to planetary geology, but its role can be misconstrued by those unfamiliar with the practice of that science. The methodological importance of analogy to geology lies in the formulation of genetic hypotheses, an absolutely essential component of geological reasoning that was either ignored or denigrated by most 20th century philosophers of science, who took the theoretical/ experimental methodology of physics to be the sole model for all of scientific inquiry. Following the seminal 19th century work of Grove Karl Gilbert, an early pioneer of planetary geology, it has long been recognized that broad experience with and understanding of terrestrial geological phenomena provide geologists with their most effective resource for the invention of potentially fruitful, working hypotheses. The actions of (1) forming such hypotheses, (2) following their consequences, and (3) testing those consequences comprise integral parts of effective geological practice in regard to the understanding of planetary surfaces. Nevertheless, the logical terminology and philosophical bases for such practice will be unfamiliar to most planetary scientists, both geologists and nongeologists. The invention of geological hypotheses involves both inductive inferences of the type Gilbert termed "empiric classification" and abductive inferences of a logical form made famous by the 19th century American logician Charles Sanders Peirce. The testing and corroboration of geological hypotheses relies less on the correspondence logic of theoretical/ experimental sciences, like physics, and more on the logic of consistency, coherence, and consilience that characterizes the investigative and historical sciences of interpretation exemplified by geology. © 2012 Elsevier Ltd.
Alexander R.D.,University of Leicester |
Pascucci I.,University of Arizona
Monthly Notices of the Royal Astronomical Society: Letters | Year: 2012
We present models of giant planet migration in evolving protoplanetary discs. We show that disc clearing by extreme-ultraviolet photoevaporation can have a strong effect on the distribution of giant planet semimajor axes. During disc clearing, planet migration is slowed or accelerated in the region where photoevaporation opens a gap in the disc, resulting in 'deserts' where few giant planets are found and corresponding 'pile-ups' at smaller and larger radii. However, the precise locations and sizes of these features are strong functions of the efficiency of planetary accretion, and therefore also strongly dependent on planet mass. We suggest that photoevaporative disc clearing may be responsible for the pile-up of ~Jupitermass planets at ~1 au seen in exoplanet surveys, and show that observations of the distribution of exoplanet semimajor axes can be used to test models of both planet migration and disc clearing. © 2012 The Authors. Monthly Notices of the Royal Astronomical Society © 2012 RAS.
Mansuripur M.,University of Arizona
Physical Review Letters | Year: 2012
The Lorentz law of force is the fifth pillar of classical electrodynamics, the other four being Maxwell's macroscopic equations. The Lorentz law is the universal expression of the force exerted by electromagnetic fields on a volume containing a distribution of electrical charges and currents. If electric and magnetic dipoles also happen to be present in a material medium, they are traditionally treated by expressing the corresponding polarization and magnetization distributions in terms of bound-charge and bound-current densities, which are subsequently added to free-charge and free-current densities, respectively. In this way, Maxwell's macroscopic equations are reduced to his microscopic equations, and the Lorentz law is expected to provide a precise expression of the electromagnetic force density on material bodies at all points in space and time. This Letter presents incontrovertible theoretical evidence of the incompatibility of the Lorentz law with the fundamental tenets of special relativity. We argue that the Lorentz law must be abandoned in favor of a more general expression of the electromagnetic force density, such as the one discovered by Einstein and Laub in 1908. Not only is the Einstein-Laub formula consistent with special relativity, it also solves the long-standing problem of "hidden momentum" in classical electrodynamics. © 2012 American Physical Society.
Healey R.,University of Arizona
Studies in History and Philosophy of Science Part B - Studies in History and Philosophy of Modern Physics | Year: 2013
Atomistic metaphysics motivated an explanatory strategy which science has pursued with great success since the scientific revolution. By decomposing matter into its atomic and subatomic parts physics gave us powerful explanations and accurate predictions as well as providing a unifying framework for the rest of science. The success of the decompositional strategy has encouraged a widespread conviction that the physical world forms a compositional hierarchy that physics and other sciences are progressively articulating. But this conviction does not stand up to a closer examination of how physics has treated composition, as a variety of case studies will show. © 2011 Elsevier Ltd.
Robey I.F.,University of Arizona
Nutrition and Metabolism | Year: 2012
Increased cancer risk is associated with select dietary factors. Dietary lifestyles can alter systemic acid-base balance over time. Acidogenic diets, which are typically high in animal protein and salt and low in fruits and vegetables, can lead to a sub-clinical or low-grade state of metabolic acidosis. The relationship between diet and cancer risk prompts questions about the role of acidosis in the initiation and progression of cancer. Cancer is triggered by genetic and epigenetic perturbations in the normal cell, but it has become clear that microenvironmental and systemic factors exert modifying effects on cancer cell development. While there are no studies showing a direct link between diet-induced acidosis and cancer, acid-base disequilibrium has been shown to modulate molecular activity including adrenal glucocorticoid, insulin growth factor (IGF-1), and adipocyte cytokine signaling, dysregulated cellular metabolism, and osteoclast activation, which may serve as intermediary or downstream effectors of carcinogenesis or tumor promotion. In short, diet-induced acidosis may influence molecular activities at the cellular level that promote carcinogenesis or tumor progression. This review defines the relationship between dietary lifestyle and acid-base balance and discusses the potential consequences of diet-induced acidosis and cancer occurrence or progression. © 2012 Robey; licensee BioMed Central Ltd.
Miller J.C.,University of Arizona
Transactions of the Institute of British Geographers | Year: 2014
As shopping malls have become increasingly common in urban and suburban landscapes, retail and consumer sciences have made these spaces more affectively intense by targeting the body of the consumer directly. Through a case study of a shopping mall in central Buenos Aires, Argentina, I suggest that non-representational theory offers advantages in studying spaces like malls for two reasons. First, shopping malls offer an opportunity to study the engineering of affect that is central to this emerging literature on materiality, politics and technology. The analysis, then, will lead to a discussion of the mall's capacity to function as a biopolitical technology as well as an economic one. Second, this approach sutures a false binary in the consumption literature between strong theories of producer power and the creativity of consumers. Interviews with mall visitors, participant observation and findings from ethnographic field work inform the figure of malls without stores (MwS), an analytic concept adapted from Deleuze and Guattari's body without organs (BwO) that reconfigures a binary reading of the consumption literature and expands the purview of what is political about these spaces. © 2012 Royal Geographical Society (with the Institute of British Geographers).
Dickinson W.R.,University of Arizona
Geosphere | Year: 2013
One hypothesis for the origin of the Grand Canyon is that a broad Hopi Lake, of which lakebeds of the Miocene Bidahochi Formation are a vestigial record, ponded to a depth great enough near the Miocene-Pliocene time boundary to spill over the topographic barrier of the Kaibab-Coconino Plateau to initiate incision of the Grand Canyon below the lake outlet. Bidahochi paleogeography indicates that Hopi Lake was a playa system that never achieved appreciable depth. Topographic relations in northern Arizona show that the maximum elevation of Bidahochi lakebeds is not compatible with lake spillover through the Grand Canyon unless post-Bidahochi deformation or pre-Bidahochi canyon-cutting altered the landscape in ways unsupported by geologic evidence, or the surface of Hopi Lake rose transiently to elevations unrecorded by any sediment. The implications of erosional episodes affecting the Colorado Plateau, the timing of drainage reversal across the central Colorado Plateau, the spatial pattern of the Colorado River drainage system, and the analogous configurations of multiple river canyons cut into Precambrian basement within the river basin also challenge the Hopi Lake spillover model. A viable alternate scenario for incision of the Grand Canyon is the concept of an ancestral Miocene Colorado River that transited the Kaibab uplift on the site of the eastern Grand Canyon, but exited the Colorado Plateau into an ancestral Virgin River drainage before capture near the site of the present central Grand Canyon by a stream working headward through the western Grand Canyon from the Grand Wash Cliffs. © 2013 Geological Society of America.
Sanov A.,University of Arizona
Annual Review of Physical Chemistry | Year: 2014
This article provides an overview of some recent advances in the modeling of photoelectron angular distributions in negative-ion photodetachment. Building on the past developments in threshold photodetachment spectroscopy that first tackled the scaling of the partial cross sections with energy, depending on the angular momentum quantum number ℓ, it examines the corresponding formulation of the central potential model and extends it to the more general case of hybrid molecular orbitals. Several conceptual approaches to understanding photoelectron angular distributions are discussed. In one approach, the angular distributions are examined based on the contributions of the symmetry-allowed s and p partial waves of the photodetached electron. In another related approach, the parent molecular orbitals are described based on their dominant s and p characters, whereas the continuum electron is described in terms of interference of the corresponding Δℓ =±1 photodetachment channels. Copyright © 2014 by Annual Reviews.
Zhou E.H.,Harvard University |
Martinez F.D.,University of Arizona |
Fredberg J.J.,Harvard University
Nature Materials | Year: 2013
One key function of the eukaryotic cell is deformability, which is well characterized phenomenologically yet remains poorly understood fundamentally. The cell's nucleus, which is stiffer than the cytoskeleton, also shares some of these same features. Importantly, it is well recognized that these elastic cellular structures are porous and dispersed in water, which is of course the principal cellular constituent. Still, although the implications of water flow on cellular mechanics are known to be important, the underlying mechanism has never been clear. Clearly, had the cell's cytoskeleton been much softer than that of the mat, it would have been mechanically impossible for the cell to penetrate into it. On the other hand, a cytoskeleton that is substantially stiffer would have made motility within the mat metabolically wasteful. Efficient motility, therefore, should favor the adaptation of the cell's mechanical properties to match those of the energy-rich mush.
Kratochwill T.R.,University of Wisconsin - Madison |
Levin J.R.,University of Arizona
Psychological Methods | Year: 2010
In recent years, single-case designs have increasingly been used to establish an empirical basis for evidence-based interventions and techniques in a variety of disciplines, including psychology and education. Although traditional single-case designs have typically not met the criteria for a randomized controlled trial relative to conventional multiple-participant experimental designs, there are procedures that can be adopted to create a randomized experiment in this class of experimental design. Our two major purposes in writing this article were (a) to review the various types of single-case design that have been and can be used in psychological and educational intervention research and (b) to incorporate randomized experimental schemes into these designs, thereby improving them so that investigators can draw more valid conclusions from their research. For each traditional single-case design type reviewed, we provide illustrations of how various forms of randomization can be introduced into the basic design structure. We conclude by recommending that traditional single-case intervention designs be transformed into more scientifically credible randomized single-case intervention designs whenever the research conditions under consideration permit. © 2010 American Psychological Association.
Thomson C.A.,University of Arizona
Nutrition in Clinical Practice | Year: 2012
Background: Breast cancer is the most commonly diagnosed cancer among women in the United States. Extensive research has been completed to evaluate the relationship between dietary factors and breast cancer risk and survival after breast cancer; however, a summary report with clinical inference is needed. Materials and Methods: This review summarizes the current epidemiological and clinical trial evidence relating diet to breast cancer incidence, recurrence, survival, and mortality. The review includes emerging epidemiological studies that assess risk within breast cancer subtypes as well as a summary of previous and ongoing dietary intervention trials designed to modify breast cancer risk. Results: The available literature suggests that both low-fat and high-fiber diets may be weakly protective against breast cancer, whereas total energy intake and alcohol appear to be positively associated. Fiber may be weakly protective possibly through modulation of estrogen, whereas fruit and vegetable intake is not clearly associated with risk. Obesity is a risk factor for postmenopausal disease, and adult weight gain should be avoided to reduce risk. In survivors, diet has the greatest potential influence on overall mortality rather than breast cancer-specific events. Conclusion: Diet is modestly associated with breast cancer risk; associations appear more pronounced for postmenopausal disease, and healthy choices after diagnosis and treatment likely support longevity more so than reduced risk for recurrent disease. © 2012 American Society for Parenteral and Enteral Nutrition.
Hale T.M.,University of Arizona
Journal of Molecular and Cellular Cardiology | Year: 2016
Fibrotic cardiac remodeling ultimately leads to heart failure - a debilitating and costly condition. Select antihypertensive agents have been effective in reducing or slowing the development of cardiac fibrosis. Moreover, some experimental studies have shown that the reduction in fibrosis induced by these agents persists long after stopping treatment. What has not been as well investigated is whether this transient treatment results in a protection against future fibrotic cardiac remodeling. In the present review, previously published studies are re-examined to assess whether the relative percent increase in collagen deposition over an off-treatment period is attenuated, relative to control, following transient antihypertensive treatment in young or adult rats. Present findings suggest that transient inhibition of the renin angiotensin system (RAS) not only produces a sustained reduction in cardiac fibrosis, but also results in a degree of protection against future collagen deposition. In addition, prior transient RAS inhibition appears to alter the cardiac fibroblast phenotype such that these cells show a muted response to myocardial injury - namely reduced proliferation, chemokine release, and collagen deposition. This review puts forth several potential mechanisms underlying this long-term cardiac protection that is afforded by transient RAS inhibition. Specifically, fibroblast phenotypic change, cardiac fibroblast apoptosis, sustained suppression of the RAS, persistent reduction in left ventricular hypertrophy, and persistent reduction in arterial pressure are each discussed. Identifying the mechanisms ultimately responsible for this change in cardiac fibroblast response to injury, hypertension, and aging may reveal novel targets for therapy. © 2015 Elsevier Ltd.
Karkoschka E.,University of Arizona
Icarus | Year: 2011
The interior rotation and motions in giant planets have generally been probed only at radio wavelengths from spacecraft near the planet, except for Jupiter's radio emission detectable from Earth. Here I suggest that Neptune's interior can be indirectly probed at visible wavelength by tracking 10 features that are connected with a stationary latitudinal speed pattern of 7. m/s amplitude. All 10 features remained aligned at the same longitude throughout the Voyager observation period in 1989. Two of them, the South Polar Wave and South Polar Feature, have been observed from Earth for ~20. years, but their extraordinary rotational stability was never recognized. They probably pinpoint Neptune's rotational period (15.9663 ± 0.0002. h), one of the largest improvements in 346. years of measuring the giant planets' rotations. The previous best estimate of Neptune's rotational period (16.108 ± 0.006. h) was based on Voyager 2 radio data (Lecacheux, A., Zarka, P., Desch, M.D., Evans, D.R. . Geophys. Res. Lett. 20, 2711-2714). The new result suggests an upward revision of the mass of Neptune's core. This finding may also question the accepted value of Uranus' rotational period. The first reliable wind measurements within 15° of Neptune's South Pole, based on tracking four features in Voyager images, show a 300. m/s eastward jet peaking near 76° South, while the area within 4° of the South Pole seems to be rotationally locked to the interior. These new observations of the stationary features and winds could address the long-standing question about the depth of the atmospheric circulation and may allow some constraints on convection currents in Neptune's interior. © 2011 Elsevier Inc.
Karkoschka E.,University of Arizona
Icarus | Year: 2011
The analysis of all suitable images taken of Neptune with the Wide Field Planetary Camera 2 on the Hubble Space Telescope between 1994 and 2008 revealed the following results. The activity of discrete cloud features located near Neptune's tropopause remained roughly constant within each year but changed significantly on the time scale of ~5. years. Discrete clouds covered 1% of the disk on average, but more than 2% in 2002. The other ~99% of the disk probed Neptune's hazes at lower altitudes. At red and near-infrared wavelengths, two dark bands around -70° and 10° latitude were perfectly steady and originated in the upper two scale heights of the troposphere, either by decreased haze opacity or by an increased methane relative humidity. At blue wavelengths, a dark band between -60° and -30° latitude was most obvious during the early years, caused by dark aerosols below the 3-bar level with single scattering albedos reduced by ~0.04, and this contrast was constant between 410 and 630. nm wavelength. The dark band decayed exponentially with a time constant of 5 ± 1 years, which can be explained by settling of the dark aerosols at a rate of 1. bar pressure difference per year. The other latitudes brightened with the same time constant but lower amplitudes. The only exception was a darkening event in the 15-30° latitude region between 1994 and 1996, which coincides with two dark spots observed in the same region during the same time period, the only dark spots seen since Voyager. The dark aerosols had a similar latitudinal distribution as the discrete clouds near the tropopause, although both were separated by four scale heights. Photometric analysis revealed a phase coefficient of 0.0028 ± 0.0010 mag/deg for the 0-2° phase-angle range observable from Earth. Neptune's sub-Earth latitude varied by less than 3° throughout the observation period providing a data set with almost constant viewing geometry. The trends observed up to 2008 continued into 2010 based on images taken with the Wide Field Camera 3. © 2011 Elsevier Inc.
Mulcahy J.J.,University of Arizona |
Carson III C.C.,University of North Carolina at Chapel Hill
European Urology | Year: 2011
Background: Diabetic patients may be more prone to penile-implant infections than other men. Objective: We sought to determine whether revision surgeries due to infection were less common in diabetic men after implantation of an inflatable penile prosthesis (IPP) impregnated with minocycline and rifampin (M/R) versus a nonimpregnated prosthesis. Design, setting, and participants: Infection-related revisions for M/R-impregnated and nonimpregnated implants were compared during a retrospective review of patient-implant and removal data recorded in the manufacturer's database. The data set included men with diabetes as an etiology of erectile dysfunction and who were implanted with their first IPPs between 2001 and 2008. Intervention: All men received three-piece IPPs. Measurements: The number of first revisions due to infection reported at any time during the study period were summarized for each group. Freedom from infection-related revisions for initial M/R-impregnated implants were compared to nonimpregnated implants with ≤84 mo of follow-up using life-table survival analysis. Infection-free survival was also compared for diabetics versus nondiabetics. Results and limitations: Mean age was 59.1 yr for the 6071 diabetic men in the M/R-impregnated group. The nonimpregnated group included 624 diabetics with a mean age of 57.6 yr. Initial revisions due to infection were reported for 1.47% of M/R-impregnated versus 4.17% of nonimpregnated implants. At 7 yr, the rate of infection-related revisions was significantly lower for M/R-impregnated (1.62%) than for nonimpregnated implants (4.24%; log-rank p < 0.0001). Diabetic men had a significantly higher rate of revisions due to infection at 7 yr (1.88%) than men without diabetes (1.53%; log-rank p = 0.0052). Conclusions: This long-term evidence from the largest known database of diabetic IPP recipients establishes that the use of an antibiotic-impregnated IPP can decrease revisions due to infection. Reducing the incidence of this devastating complication represents a significant medical advance in erectile restoration for diabetic patients. © 2011 European Association of Urology. Published by Elsevier B.V. All rights reserved.
Wang A.,CAS Institute of Atmospheric Physics |
Zeng X.,University of Arizona
Journal of Climate | Year: 2013
Land surface air temperature (SAT) is one of the most important variables in weather and climate studies, and its diurnal cycle is also needed for a variety of applications. Global long-term hourly SAT observational data, however, do not exist. While such hourly products could be obtained from global reanalyses, they are found to be unrealistic in representing the SAT diurnal cycle. Global hourly 0.5° SAT datasets are developed here based on four reanalysis products [Modern-Era Retrospective Analysis for Research and Applications (MERRA for 1979-2009), 40-yr ECMWF Re- Analysis (ERA-40 for 1958-2001),ECMWFInterim Re-Analysis (ERA-Interim for 1979-2009), and NCEP- NCAR reanalysis for 1948-2009)] and the Climate Research Unit Time Series version 3.10 (CRU TS3.10) for 1948-2009. The three-step adjustments include the spatial downscaling to 0.5° grid cells, the temporal interpolation from 6-hourly (in ERA-40 and NCEP-NCAR reanalysis) to hourly using the MERRA hourly SAT climatology for each day (and the linear interpolation from 3-hourly in ERA-Interim to hourly), and the bias correction in both monthly-mean maximum (Tmax) and minimum (Tmin) SAT using the CRU data. The final products have exactly the same monthly Tmax and Tmin as the CRU data, and perform well in comparison with in situ hourly measurements over six sites and with a regional daily SAT dataset over Europe. They agree with each other much better than the original reanalyses, and the spurious SAT jumps of reanalyses over some regions are also substantially eliminated. One of the uncertainties in the final products can be quantified by their differences in the true monthly mean (using 24-hourly values) and the monthly averaged diurnal cycle. © 2013 American Meteorological Society.
Wang A.,CAS Institute of Atmospheric Physics |
Zeng X.,University of Arizona
Journal of Geophysical Research: Atmospheres | Year: 2012
As the highest plateau in the world, the Tibetan Plateau (TP) strongly affects regional weather and climate as well as global atmospheric circulations. Here six reanalysis products (i.e., MERRA, NCEP/NCAR-1, CFSR, ERA-40, ERA-Interim, and GLDAS) are evaluated using in situ measurements at 63 weather stations over the TP from the Chinese Meteorological Administration (CMA) for 1992-2001 and at nine stations from field campaigns (CAMP/Tibet) for 2002-2004. The measurement variables include daily and monthly precipitation and air temperature at all CMA and CAMP/Tibet stations as well as radiation (downward and upward shortwave and longwave), wind speed, humidity, and surface pressure at CAMP stations. Four statistical quantities (correlation coefficient, ratio of standard deviations, standard deviation of differences, and bias) are computed, and a ranking approach is also utilized to quantify the relative performance of reanalyses with respect to each variable and each statistical quantity. Compared with measurements at the 63 CMA stations, ERA-Interim has the best overall performance in both daily and monthly air temperatures, while MERRA has a high correlation with observations. GLDAS has the best overall performance in both daily and monthly precipitation because it is primarily based on the merged precipitation product from surface measurements and satellite remote sensing, while ERA-40 and MERRA have the highest correlation coefficients for daily and monthly precipitation, respectively. Compared with measurements at the nine CAMP stations, CFSR shows the best overall performance, followed by GLDAS, although the best ranking scores are different for different variables. It is also found that NCEP/NCAR-1 reanalysis shows the worst overall performance compared with both CMA and CAMP data. Since no reanalysis product is superior to others in all variables at both daily and monthly time scales, various reanalysis products should be combined for the study of weather and climate over the TP. Copyright 2012 by the American Geophysical Union.
Girardeau M.D.,University of Arizona |
Astrakharchik G.E.,Polytechnic University of Catalonia
Physical Review Letters | Year: 2012
The ground state of a one-dimensional (1D) quantum gas of dipoles oriented perpendicular to the longitudinal axis, with a strong 1/x3 repulsive potential, is studied at low 1D densities n. Near contact the dependence of the many-body wave function on the separation x of two particles reduces to a two-body wave function Ψrel(x). Immediately after a sudden rotation of the dipoles so that they are parallel to the longitudinal axis, this wave function will still be that of the repulsive potential, but since the potential is now that of the attractive potential, it will not be stationary. It is shown that as nd2→0 the rate of change of this wave function approaches zero. It follows that for small values of nd2, this state is metastable and is an analog of the super Tonks-Girardeau state of bosons with a strong zero-range attraction. The dipolar system is equivalent to a spinor Fermi gas with spin z components σ= (perpendicular to the longitudinal axis) and σ= (parallel to the longitudinal axis). A Fermi-Fermi mapping from spinor to spinless Fermi gas followed by the standard 1960 Fermi-Bose mapping reduces the Fermi system to a Bose gas. Potential experiments realizing the sudden spin rotation with ultracold dipolar gases are discussed, and a few salient properties of these states are accurately evaluated by a MonteCarlo method. © 2012 American Physical Society.
Zhang B.,University of Nevada, Las Vegas |
Yan H.,Peking University |
Yan H.,University of Arizona
Astrophysical Journal | Year: 2011
The recent Fermi observation of GRB 080916C shows that the bright photosphere emission associated with a putative fireball is missing, which suggests that the central engine likely launches a Poynting-flux-dominated (PFD) outflow.We propose a model of gamma-ray burst (GRB) prompt emission in the PFD regime, namely, the Internal-Collision-induced MAgnetic Reconnection and Turbulence (ICMART) model. It is envisaged that the GRB central engine launches an intermittent, magnetically dominated wind, and that in the GRB emission region, the ejecta is still moderately magnetized (e.g., 1 ≲ σ ≲ 100). Similar to the internal shock (IS) model, the mini-shells interact internally at the radius RIS ∼ σ2cδt. Most of these early collisions, however, have little energy dissipation, but serve to distort the ordered magnetic field lines entrained in the ejecta. At a certain point, the distortion of magnetic field configuration reaches the critical condition to allow fast reconnection seeds to occur, which induce relativistic MHD turbulence in the interaction regions. The turbulence further distorts field lines easing additional magnetic reconnections, resulting in a runway release of the stored magnetic field energy (an ICMART event). Particles are accelerated either directly in the reconnection zone, or stochastically in the turbulent regions, which radiate synchrotron photons that power the observed gamma rays. Each ICMART event corresponds to a broad pulse in the GRB light curve, and a GRB is composed of multiple ICMART events. This model retains the merits of IS and other models, but may overcome several difficulties/issues faced by the IS model (e.g., low efficiency, fast cooling, electron number excess, Amati/Yonetoku relation inconsistency, and missing bright photosphere). Within this model, the observed GRB variability timescales could have two components, one slow component associated with the central engine time history, and another fast component associated with relativistic magnetic turbulence in the emission region. The model predicts a decrease of gamma-ray polarization degree and Ep in each ICMART event (broad pulse) during the prompt GRB phase, as well as a moderately magnetized external reverse shock. The model may be applied to the GRBs that have time-resolved, featureless Band-function spectra, such as GRB 080916C and most GRBs detected by Fermi LAT. © 2011 The American Astronomical Society. All rights reserved.
Rogers T.M.,University of Arizona
Astrophysical Journal | Year: 2011
We present axisymmetric simulations of the coupled convective and radiative regions in the Sun in order to investigate the angular momentum evolution of the radiative interior. Both hydrodynamic and magnetohydrodynamic models were run. We find an initial rapid adjustment in which the differential rotation of the convection zone viscously spreads into the radiative interior, thus forming a "tachocline." In polar regions, the subsequent spread of the tachocline is halted by a counterrotating meridional circulation cell which develops in the tachocline. Near the equator such a counterrotating cell is more intermittent and the tachocline penetration depth continues to increase, albeit more slowly than previously predicted. In the magnetic models, we impose a dipolar field initially confined to the radiative interior. The behavior of the magnetic models is very similar to their non-magnetic counterparts. Despite being connected to the convection zone, very little angular momentum is transferred between the convective and radiative regions. Therefore, while it appears that a magnetic field is not necessary to stop the tachocline spread, it also does not promote such a spread if connected to the convection zone. © 2011. The American Astronomical Society. All rights reserved..
Brown M.F.,University of Arizona
Biochemistry | Year: 2012
Membrane biochemists are becoming increasingly aware of the role of lipid-protein interactions in diverse cellular functions. This review describes how conformational changes in membrane proteins, involving folding, stability, and membrane shape transitions, potentially involve elastic remodeling of the lipid bilayer. Evidence suggests that membrane lipids affect proteins through interactions of a relatively long-range nature, extending beyond a single annulus of next-neighbor boundary lipids. It is assumed the distance scale of the forces is large compared to the molecular range of action. Application of the theory of elasticity to flexible soft surfaces derives from classical physics and explains the polymorphism of both detergents and membrane phospholipids. A flexible surface model (FSM) describes the balance of curvature and hydrophobic forces in lipid-protein interactions. Chemically nonspecific properties of the lipid bilayer modulate the conformational energetics of membrane proteins. The new biomembrane model challenges the standard model (the fluid mosaic model) found in biochemistry texts. The idea of a curvature force field based on data first introduced for rhodopsin gives a bridge between theory and experiment. Influences of bilayer thickness, nonlamellar-forming lipids, detergents, and osmotic stress are all explained by the FSM. An increased awareness of curvature forces suggests that research will accelerate as structural biology becomes more closely entwined with the physical chemistry of lipids in explaining membrane structure and function. © 2012 American Chemical Society.
Narayanan D.,University of Arizona |
Hopkins P.F.,University of California at Berkeley
Monthly Notices of the Royal Astronomical Society | Year: 2013
The CO-H2 conversion factor (XCO; otherwise known as the X-factor) is observed to be remarkably constant in the MilkyWay and in the Local Group (aside from the Small Magellanic Cloud). To date, our understanding of why XCO should be so constant remains poor. Using a combination of extremely high-resolution (~1 pc) galaxy evolution simulations and molecular line radiative transfer calculations, we suggest that XCO displays a narrow range of values in the Galaxy due to the fact that molecular clouds share very similar physical properties. In our models, this is itself a consequence of stellar feedback competing against gravitational collapse. Giant molecular clouds (GMCs) whose lifetimes are regulated by radiative feedback show a narrow range of surface densities, temperatures and velocity dispersions with values comparable to those seen in the Milky Way. As a result, the X-factors from these clouds show reasonable correspondence with observed data from the Local Group, and a relatively narrow range. On the other hand, feedback-free clouds collapse to surface densities that are larger than those seen in the Galaxy, and hence result in X-factors that are systematically too large compared to theMilkyWay's. We conclude that radiative feedback within GMCs can generate cloud properties similar to those observed in the Galaxy, and hence a roughly constant Milky Way X-factor in normal, quiescent clouds. © 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.
Basha E.,University of Arizona |
O'Neill H.,University of Massachusetts Amherst |
Vierling E.,University of Massachusetts Amherst
Trends in Biochemical Sciences | Year: 2012
The small heat shock proteins (sHSPs) and the related α-crystallins (αCs) are virtually ubiquitous proteins that are strongly induced by a variety of stresses, but that also function constitutively in multiple cell types in many organisms. Extensive research has demonstrated that a majority of sHSPs and αCs can act as ATP-independent molecular chaperones by binding denaturing proteins and thereby protecting cells from damage due to irreversible protein aggregation. As a result of their diverse evolutionary history, their connection to inherited human diseases, and their novel protein dynamics, sHSPs and αCs are of significant interest to many areas of biology and biochemistry. However, it is increasingly clear that no single model is sufficient to describe the structure, function or mechanism of action of sHSPs and αCs. In this review, we discuss recent data that provide insight into the variety of structures of these proteins, their dynamic behavior, how they recognize substrates, and their many possible cellular roles. © 2011 Elsevier Ltd.
Sevian H.,University of Massachusetts Boston |
Talanquer V.,University of Arizona
Chemistry Education Research and Practice | Year: 2014
Dominant educational approaches in chemistry focus on the learning of somewhat isolated concepts and ideas about chemical substances and reactions. Reform efforts often seek to engage students in the generation of knowledge through the investigation of chemical phenomena, with emphasis on the development and application of models to build causal explanations and predict outcomes. However, chemistry has been characterized as a technoscience that blends scientific pursuit and technological goals. Besides searching for explanations, our discipline also involves the design of substances and processes to address relevant problems, as well as the evaluation of social, economic, and environmental benefits, costs, and risks associated with chemical knowledge and products. In order to develop authentic curricula, instruction, and assessments that are better aligned with the core goals and practices of chemistry, we need to understand how students' chemical thinking progresses over time. We define chemical thinking as the development and application of chemical knowledge and practices with the main intent of analyzing, synthesizing, and transforming matter for practical purposes. In this paper we present a blueprint of a theoretically sound and evidence-based foundation for an educational framework centered on the idea of chemical thinking. Our investigations are focused on the development of a learning progression that describes likely pathways in the evolution of students' chemical thinking with training in the discipline from grade 8 (age 13-14) through 16 (undergraduate completion). © 2014 The Royal Society of Chemistry.
Dvorak B.,University of Arizona
Journal of Pediatrics | Year: 2010
Maternal milk is a complex fluid, with multifunctional roles within the developing gastrointestinal tract. Epidermal growth factor (EGF) and heparin-binding EGF-like growth factor (HB-EGF) are members of the family of EGF-related peptides. Biological actions of these growth factors are mediated via interaction with the EGF-receptor (EGF-R). In the early postnatal period, breast milk is the major source of EGF for the developing intestinal mucosa. HB-EGF is also detected in breast milk, but in concentrations 2 to 3 times lower than EGF. With normal physiological conditions, the intestinal epithelium undergoes a continuing process of cell proliferation, differentiation, and maturation. EGF plays an important role in these processes. In pathophysiologic situations, EGF contributes to epithelial protection from injury and post-injury mucosal repair. Necrotizing enterocolitis (NEC) is a devastating disease affecting infants born prematurely. The pathogenesis of NEC is not known, and there is no effective treatment for this disease. In an experimental NEC model, oral administration of a physiological dose of EGF significantly reduces the incidence and severity of NEC. HB-EGF provides similar protection against NEC, but only when pharmacological doses are used. Further studies are necessary before EGF can be introduced as an efficient therapeutic approach of intestinal injury. © 2010 Mosby, Inc. All rights reserved.
Rains S.A.,University of Arizona
Health Communication | Year: 2014
The reported study examines the implications of anonymity and stigma in the form of illness-related embarrassment for self-disclosure in the context of health blogging. Drawing from theorizing about anonymous communication and stigma, anonymity is argued to be strategically used by individuals who are embarrassed by their illness and to moderate the relationship between embarrassment and self-disclosure. Data from 114 individuals who blog about their experiences coping with a health condition were examined to test study hypotheses. Illness-related embarrassment was positively associated with anonymity. Additionally, anonymity moderated the relationship between embarrassment and self-disclosure. Among bloggers with relatively higher levels of anonymity, illness-related embarrassment was positively associated with self-disclosure. The results suggest that anonymity is strategically used and fosters self-disclosure among individuals who are embarrassed by their illness. © 2014 Copyright Taylor and Francis Group, LLC.
Taljanovic M.S.,University of Arizona
Radiographics : a review publication of the Radiological Society of North America, Inc | Year: 2011
Injuries of the intrinsic and extrinsic wrist ligaments can lead to chronic wrist pain and carpal instability, while injuries of the triangular fibrocartilage complex are a frequent cause of ulnar-sided wrist pain. Currently, magnetic resonance (MR) arthrography is the preferred imaging modality for the evaluation of these structures, but good results can also achieved with MR imaging without preceding arthrography and computed tomographic (CT) arthrography. Promising results have been published on ultrasonography (US) and sonoarthrography of the intrinsic wrist ligaments and the triangular fibrocartilage complex and on US of the majority of extrinsic wrist ligaments. Visualization of these structures can be achieved by using high-frequency linear transducers. US has the advantages of MR imaging and MR arthrography: lower cost, no known contraindication for imaging, and real-time technique with possible dynamic evaluation. This technique does not require imaging guided intraarticular injection of contrast medium prior to MR arthrography or CT arthrography and does not use ionizing radiation; however, US is operator dependent, which can be compensated for by using standardized imaging techniques. Supplemental material available at http://radiographics.rsna.org/lookup/suppl/doi:10.1148/rg.e44/-/DC1.
Krupinski E.A.,University of Arizona
Seminars in Nuclear Medicine | Year: 2011
The accurate and efficient interpretation of medical images relies on a host of factors. Clearly the technologies and methods used to acquire, process, transmit, store, and display the image and associated data are critical, but they are only one-half of the equation. In the end, the final diagnostic interpretation and recommendations for further action lie with the clinician. Ideally we would like to believe that all decisions rendered by competent clinicians are correct, but the interpretation task is not always easy or black and white. Thus, decisions are not always absolutely conclusive, are often formulated with plausible alternatives, and errors in interpretation can and do occur regularly. The discipline of medical image perception seeks an improved understanding of the perceptual factors that underlie the creation and interpretation of medical images, with the belief that improved diagnostic performance with the use of imaging devices can be achieved by the development of systems that are optimized for the interpretation of visual diagnostic information. Perception research can identify specific reasons for missed diagnoses, thereby helping to train physicians and eliminate diagnostic errors, and clarifying situations in which errors are a consequence of fundamentally ambiguous information rather than poor reader performance. The goal of this article is to provide a short review of the history of the discipline of medical image perception, highlight key research areas, and provide a look toward the future regarding the role that medical image perception research will continue to fill as imaging technology in medicine advances and develops. © 2011 Elsevier Inc.
Crossfield I.J.M.,University of Arizona
Publications of the Astronomical Society of the Pacific | Year: 2015
Detailed characterization of an extrasolar planet’s atmosphere provides the best hope for distinguishing the makeup of its outer layers, and the only hope for understanding the interplay between initial composition, chemistry, dynamics and circulation, and disequilibrium processes. In recent years, some areas have seen rapid progress, while developments in others have come more slowly and/or have been hotly contested. This article gives an observer’s perspective on the current understanding of extrasolar planet atmospheres prior to the considerable advances expected from the next generation of observing facilities. Atmospheric processes of both transiting and directly imaged planets are discussed, including molecular and atomic abundances, cloud properties, thermal structure, and planetary energy budgets. In the future we can expect a continuing and accelerating stream of new discoveries, which will fuel the ongoing exoplanet revolution for many years to come. © 2015, The Astronomical Society of the Pacific. All rights reserved.
Fass R.,University of Arizona
American Journal of Gastroenterology | Year: 2012
Patients with erosive esophagitis (EE) account for 30% of patients with gastroesophageal reflux disease; only a minority of these patients fail to achieve healing on treatment with a proton pump inhibitor (PPI), once-daily, for 8 weeks. For those patients with EE who have failed to heal on a PPI, given once-daily, current practice is to double the PPI dose although there is little published evidence to support this. In this issue of the American Journal of Gastroenterology, authors from Japan have demonstrated that double-dose PPI produced higher healing rates when given as a split, twice-daily dose than as a once-daily dose for patients with EE who had failed initial therapy with rabeprazole 10 mg once-daily. Quadruple-dose PPI, given as a split dose, did not increase the healing rates but did produce better symptom control, albeit limited, compared with double-dose PPI, given twice-daily. Because subjects, initially, received a lower PPI dose than that generally indicated for EE (rabeprazole 20 mg daily), this study does not provide the eagerly awaited justification for double-dose PPI therapy in patients with EE who have failed standard-dose PPI once-daily. However, it does demonstrate the clinical advantage of a split-dose regimen (AM and PM), compared with a once-daily regimen, when doubling the dose of a PPI for patients with residual EE after initial therapy. © 2012 by the American College of Gastroenterology.
Lipsy R.J.,University of Arizona
The American journal of managed care | Year: 2010
Of the new generation of multiple sclerosis (MS) drugs, 4 oral agents--dalfampridine, laquinimod, cladribine, and fingolimod--could produce significant changes in the treatment landscape for MS. Current first-line treatments, which are administered via injection, are associated with poor treatment adherence, often due to lack of efficacy (perceived and real), adverse drug reactions, cost, and injection anxiety. Although concerns about safety and cost remain, preliminary results indicate that these oral agents are as effective as, or even more effective than, current injectable treatments. Oral MS agents are expected to cost patients less in out-of-pocket expenses, which will likely increase treatment adherence and lead to an overall reduction in medical costs. While many patients may prefer an oral MS drug, the ultimate choice of therapy will be a shared patient-physician decision based on a multitude of factors, including the efficacy of the current treatment regimen, patient compliance history, and the difference in out-of-pocket expenses.
Chamberlain S.A.,Rice University |
Chamberlain S.A.,Simon Fraser University |
Bronstein J.L.,University of Arizona |
Rudgers J.A.,Rice University |
Rudgers J.A.,University of New Mexico
Ecology Letters | Year: 2014
The net effects of interspecific species interactions on individuals and populations vary in both sign (-, 0, +) and magnitude (strong to weak). Interaction outcomes are context-dependent when the sign and/or magnitude change as a function of the biotic or abiotic context. While context dependency appears to be common, its distribution in nature is poorly described. Here, we used meta-analysis to quantify variation in species interaction outcomes (competition, mutualism, or predation) for 247 published articles. Contrary to our expectations, variation in the magnitude of effect sizes did not differ among species interactions, and while mutualism was most likely to change sign across contexts (and predation least likely), mutualism did not strongly differ from competition. Both the magnitude and sign of species interactions varied the most along spatial and abiotic gradients, and least as a function of the presence/absence of a third species. However, the degree of context dependency across these context types was not consistent among mutualism, competition and predation studies. Surprisingly, study location and ecosystem type varied in the degree of context dependency, with laboratory studies showing the highest variation in outcomes. We urge that studying context dependency per se, rather than focusing only on mean outcomes, can provide a general method for describing patterns of variation in nature. © 2014.
Granzier H.,University of Arizona
Advances in Experimental Medicine and Biology | Year: 2010
This review covers recent developments in the titin field. Most recent reviews have discussed titin's role in cardiac function: here we will mainly focus on skeletal muscle, and discuss recent advances in the understanding of titin's role in skeletal muscle function and disease. © Springer Science+Business Media, LLC 2010.
Quintero I.,Yale University |
Wiens J.J.,University of Arizona
Ecology Letters | Year: 2013
A key question in predicting responses to anthropogenic climate change is: how quickly can species adapt to different climatic conditions? Here, we take a phylogenetic approach to this question. We use 17 time-calibrated phylogenies representing the major tetrapod clades (amphibians, birds, crocodilians, mammals, squamates, turtles) and climatic data from distributions of > 500 extant species. We estimate rates of change based on differences in climatic variables between sister species and estimated times of their splitting. We compare these rates to predicted rates of climate change from 2000 to 2100. Our results are striking: matching projected changes for 2100 would require rates of niche evolution that are > 10 000 times faster than rates typically observed among species, for most variables and clades. Despite many caveats, our results suggest that adaptation to projected changes in the next 100 years would require rates that are largely unprecedented based on observed rates among vertebrate species. © 2013 John Wiley & Sons Ltd/CNRS.
Henriksen E.J.,University of Arizona
Current diabetes reviews | Year: 2010
Insulin resistance of glucose transport and metabolism in insulin-sensitive tissues is a primary defect leading to the development of type 2 diabetes. While the etiology of insulin resistance is multifactorial, one factor associated with reduced insulin action is enhanced activity of the serine/threonine kinase glycogen synthase kinase-3 (GSK-3) in skeletal muscle, liver, and adipose tissue. GSK-3 is involved in numerous cellular functions, including glycogen synthesis, protein synthesis, gene transcription, and cell differentiation. Evidence from muscle and fat cell lines and in skeletal muscle from a variety of obese rodent models and from type 2 diabetic humans supports a role of GSK-3 overactivity in the development of insulin resistance of glucose transport and glycogenesis. Studies utilizing highly selective GSK-3 inhibitors indicate that GSK-3 overactivity in obesity is associated with enhanced IRS-1 serine phosphorylation and defective IRS-1-dependent signaling, ultimately resulting in reduced GLUT-4 translocation and glucose transport activity in skeletal muscle. A role of GSK-3 overactivity in the exaggerated hepatic glucose production of type 2 diabetes has also been reported. Recent studies have demonstrated that oxidative stress, resulting from enhanced exposure to oxidants, causes impaired insulin signaling and insulin resistance of skeletal muscle glucose transport, in part due to reduced suppression of GSK-3 activity and increased IRS-1 Ser(307) phosphorylation. The evidence to date supports an important role of GSK-3 dysfunction in the multifactorial etiology of insulin resistance in skeletal muscle. GSK-3 remains an important target for interventions designed to improve insulin action in obesity-associated insulin resistance and type 2 diabetes.
Cohen W.R.,University of Arizona |
Friedman E.A.,Harvard University
American Journal of Obstetrics and Gynecology | Year: 2015
Recent guidelines issued jointly by the American College of Obstetricians and Gynecologists and the Society for Maternal-Fetal Medicine for assessing labor progress differ substantially from those described initially by Friedman, which have guided clinical practice for decades. The guidelines are based on results obtained from new and untested methods of analyzing patterns of cervical dilatation and fetal descent. Before these new guidelines are adopted into clinical practice, the results obtained by these unconventional analytic approaches should be validated and shown to be superior, or at least equivalent, to currently accepted standards. The new guidelines indicate the patterns of labor originally described by Friedman are incorrect and, further, are inapplicable to modern obstetric practice. We contend that the original descriptions of normal and abnormal labor progress, which were based on direct clinical observations, accurately describe progress in dilatation and descent, and that the differences reported more recently are likely attributable to patient selection and the potential inaccuracy of very high-order polynomial curve-fitting methods. The clinical evaluation of labor is a process of serially estimating the likelihood of a safe vaginal delivery. Because many factors contribute to that likelihood, such as cranial molding, head position and attitude, and the bony architecture and capacity of the pelvis, graphic labor patterns should never be used in isolation. The new guidelines are based heavily on unvalidated notions of labor progress and ignore clinical parameters that should remain cornerstones of intrapartum decision-making. © 2015 Elsevier Inc.
Vanderah T.W.,University of Arizona
Clinical Journal of Pain | Year: 2010
Similar to μ opioid receptors, κ and δ opioid receptors reside in the periphery, the dorsal root ganglion, the spinal cord, and in supraspinal regions associated with pain modulation. Both δ and κ opioid agonists have been shown to activate pain inhibitory pathways in the central nervous system. Yet, currently there are only a few pharmacologic agents that target κ receptors, and none that target δ receptors. Spurred by the need for an efficacious analgesic without the unwanted side effects associated with the typical clinical profile of μ opioid agonists, new research has provided insight into why the development of effective κ and δ opioid receptor agonists has remained elusive thus far, and importantly, how these obstacles may be overcome. For example, for δ opioid agonists to be effective, a state of inflammation may be required as this induces δ opioid receptors to migrate to the surface of neuronal cells and thereby become accessible to δ opioid agonists. Studies have shown that δ opioid agonists can provide relief of inflammatory pain and malignant bone pain. Meanwhile, peripherally restricted κ opioid agonists have been developed to target κ opioid receptors located on visceral and somatic afferent nerves for relief of inflammatory, visceral, and neuropathic chronic pain. The recently shown efficacy of these analgesics combined with a possible lower abuse potential and side effect burden than μ opioid receptor agonists makes δ and peripherally restricted κ opioid receptor agonists promising targets for treating pain. © 2010 Lippincott Williams & Wilkins, Inc.
Mansuripur M.,University of Arizona
Optics Communications | Year: 2010
The momentum of light inside ponderable media has an electromagnetic part and a mechanical part. The local and instantaneous density of the electromagnetic part of the momentum is given by the Poynting vector divided by the square of the speed of light in vacuum, irrespective of the nature of the electromagnetic fields or the local or global properties of the material media. The mechanical part of the momentum is associated with the action of the electromagnetic field on the atomic constituents of the media, as specified by the Lorentz law of force. Proper interpretation and application of the Maxwell-Lorentz equations within the material bodies as well as at their surfaces and interfaces is all that is needed to obtain a complete picture of the momentum of light, including detailed numerical values at each and every point in space and time. That the Abraham-Minkowski controversy surrounding the momentum of light inside material media has persisted for nearly a century is due perhaps to an insufficient appreciation for the completeness and consistency of the macroscopic Maxwell-Lorentz theory, inadequate treatment of the electromagnetic force and torque at the material boundaries, and an undue emphasis on the necessity of coupling the equations of electrodynamics to those of the theory of elasticity for proper treatment of mechanical momentum. The present paper reports the resolution of the Abraham-Minkowski controversy within the framework of the classical theory of electrodynamics, without resort to such complicating and ultimately unnecessary factors as pseudo-momentum, special surface forces, alternative energy-momentum tensors, and hidden momenta, that have caused so much confusion for such a long period of time. © 2010 Elsevier B.V. All rights reserved.
Hameroff S.R.,University of Arizona
Behavioral and Brain Sciences | Year: 2013
The Orch OR theory suggests that quantum computations in brain neuronal dendritic-somatic microtubules regulate axonal firings to control conscious behavior. Within microtubule subunit proteins, collective dipoles in arrays of contiguous amino acid electron clouds enable quantum channels suitable for topological dipole qubits able to physically represent cognitive values, for example, those portrayed by Pothos & Busemeyer (P&B) as projections in abstract Hilbert space. © 2013 Cambridge University Press.
Zheng H.,University of Arizona
Journal of Advanced Transportation | Year: 2014
Efficient transportation of evacuees during an emergency has long been recognized as a challenging issue. This paper investigates emergency evacuation strategies that rely on public transit, where buses run continuously, rather than fixed route, based upon the spatial and temporal information of evacuee needs. We formulated an optimal bus operating strategy that minimizes the exposed casualty time rather than operational cost, as a deterministic mixed-integer program, and investigated the solution algorithm. A Lagrangian-relaxation-based solution algorithm was developed for the proposed model. Numerical experiments with different problem sizes were conducted to evaluate the method. Copyright © 2013 John Wiley & Sons, Ltd. Copyright © 2013 John Wiley & Sons, Ltd.
Ellis B.J.,University of Arizona
Hormones and Behavior | Year: 2013
This article is part of a Special Issue "Puberty and Adolescence".Life history theory provides an overarching framework for explaining the development of individual differences in reproductive strategies and highlights the role of familial and ecological conditions in regulating pubertal timing. Parental investment and sexual selection models afford a powerful framework for explaining the emergence of sex differences in reproductive strategies and suggest that pubertal timing in males and females is differentially sensitive to psychosocial stress. The West-Eberhard's (2003) model of switch-controlled modular systems provides the foundation for a comprehensive analysis of variation in reproductive strategies at the level of mechanism and development. Applied to puberty, this model provides a framework for explaining how genes and environments interact over development, are modulated by extant phenotypic characteristics, and operate through control of regulatory switch mechanisms across multiple levels of the hypothalamic-pituitary-gonadal axis. Taken together, life history theory, parental investment and sexual selection models, and the West-Eberhard framework enable an integrated evolutionary-developmental analysis of between-sex variation and within-sex variation in pubertal processes and their role in regulating alternative life history strategies. © 2013 Elsevier Inc.
Bandarian V.,University of Arizona
Biochimica et Biophysica Acta - Proteins and Proteomics | Year: 2012
The radical S-adenosyl-l-methionine (SAM) superfamily is a widely distributed group of iron-sulfur containing proteins that exploit the reactivity of the high energy intermediate, 5′-deoxyadenosyl radical, which is produced by the reductive cleavage of SAM, to carry-out complex radical-mediated transformations. The reactions catalyzed by radical SAM enzymes range from simple group migrations to complex reactions in protein and RNA modification. This review will highlight three radical SAM enzymes that catalyze reactions involving modified guanosines in the biosynthesis pathways of the hypermodified tRNA base wybutosine; secondary metabolites of 7-deazapurine structure, including the hypermodified tRNA base queuosine; and the redox cofactor F 420. This article is part of a Special Issue entitled: Radical SAM enzymes and Radical Enzymology. © 2012 Elsevier B.V. All rights reserved.
Pries A.R.,Charite - Medical University of Berlin |
Secomb T.W.,University of Arizona
Physiology | Year: 2014
The adequate and efficient functioning of the microcirculation requires not only numerous vessels providing a large surface area for transport but also a structure that provides short diffusion distances from capillaries to tissue and efficient distribution of convective blood flow. Theoretical models show how a combination of angiogenesis, remodeling, and pruning in response to hemodynamic and metabolic stimuli, termed “angioadaptation,” generates well organized, functional networks. © 2014 Int. Union Physiol. Sci./Am. Physiol. Soc.
Bazinet A.L.,University of Maryland University College |
Zwickl D.J.,University of Arizona |
Cummings M.P.,University of Maryland University College
Systematic Biology | Year: 2014
We introduce molecularevolution.org, a publicly available gateway for high-throughput, maximum-likelihood phylogenetic analysis powered by grid computing. The gateway features a GARLI 2.0web service that enables a user to quickly and easily submit thousands of maximum likelihood tree searches or bootstrap searches that are executed in parallel on distributed computing resources. The GARLI web service allows one to easily specify partitioned substitution models using a graphical interface, and it performs sophisticated post-processing of phylogenetic results. Although the GARLI web service has been used by the research community for over three years, here we formally announce the availability of the service, describe its capabilities, highlight new features and recent improvements, and provide details about how the grid system efficiently delivers high-quality phylogenetic results. © The Author(s) 2014.
McGill B.J.,University of Arizona |
Nekola J.C.,University of New Mexico
Oikos | Year: 2010
Ecologists often believe the discovery of mechanism to be the central goal of scientific research. While many macroecologists have inherited this view, to date they have been much more efficient at producing patterns than identifying their underlying processes. We discuss several possible attitudes for macroecologists to adopt in this context while also arguing that in fact macroecology already has many mechanisms that are ignored. We briefly describe six of these: central limit theorem, fractals, random sampling and placement, neutral theory (and descendents), concordance of forces, and maximum entropy. We explore why these mechanisms are overlooked and discuss whether they should be. We conclude that macroecology needs to take a more pragmatic, less ideological approach to mechanism. We apply this viewpoint to the recent controversy over maximum entropy and suggest that maximum entropy needs to be viewed more pragmatically and less ideologically. © 2009 The Authors. Journal compilation © 2010 Oikos.
Budhu M.,University of Arizona
International Journal of Geomechanics | Year: 2010
This paper presents the formulation of the mechanics governing the changes in stress state from groundwater pumping. A two-layer alluvium consisting of a cemented alluvium layer on top of an unconfined aquifer alluvium layer is considered. It is shown that the stress state in the aquifer alluvium consists of compression, simple shear and couple stresses. The shear stresses on the vertical planes and horizontal planes are not equal. Consequently, a Cosserat rather than the conventionally used Cauchy continuum better simulates the stresses in the aquifer alluvium. Land subsidence from groundwater level decline consists of vertical compression (consolidation), shear displacement and macrorotation. The latter occurs when conditions are favorable for the microrotation imposed by asymmetric stresses to become macrorotation. Earth fissures are formed in aquifer alluvium from groundwater pumping by simple shear on vertical planes and rotation and not by tension as commonly suggested. Earth fissures are formed in the upper cemented alluvium by simple shear strains and rotations. Highly cemented alluviums are more prone to earth fissure formation than weakly cemented alluviums. It is shown that there is a critical characteristic length of √2 times the aquifer alluvium thickness below which earth fissures would, theoretically, not develop. The distances from the well face at which earth fissures will form depend not on the total drop in groundwater level but on the gradient of the groundwater profile. The slope of the subsidence bowl, which consists of simple shear strain and rotation, is established as an indicator for the initiation of earth fissures. © 2011 ASCE.
Zhang L.,University of Arizona
International Journal of Geomechanics | Year: 2010
This paper presents a method for predicting the nonlinear response of torsionally loaded piles in a two-layer soil profile, such as a clay or sand layer underlain by rock. The shear modulus of the upper soil is assumed to vary linearly with depth and the shear modulus of the lower soil is assumed to vary linearly with depth and then stay constant below the pile tip. The method uses the variational principle to derive the governing differential equations of a pile in a two-layer continuum and the elastic response of the pile is then determined by solving the derived differential equations. To consider the effect of soil yielding on the behavior of piles, the soil is assumed to behave linearly elastically at small strain levels and yield when the shear stress on the pile-soil interface exceeds the corresponding maximum shear resistance. To determine the maximum pile-soil interface shear resistance, methods that are available in the literature can be used. The proposed method is verified by comparing its results with existing elastic solutions and published small-scale model pile test results. Finally, the proposed method is used to analyze two full-scale field test piles and the predictions are in reasonable agreement with the measurements. © 2010 ASCE.
Shkolnik E.L.,Lowell Observatory |
Barman T.S.,University of Arizona
Astronomical Journal | Year: 2014
The spectral energy distribution, variability, and evolution of the high-energy radiation from an M dwarf planet host is crucial in understanding the planet's atmospheric evolution and habitability and in interpreting the planet's spectrum. The star's extreme-UV (EUV), far-UV (FUV), and near-UV (NUV) emission can chemically modify, ionize, and erode the atmosphere over time. This makes determining the lifetime exposure of such planets to stellar UV radiation critical for both the evolution of a planet's atmosphere and our potential to characterize it. Using the early M star members of nearby young moving groups, which sample critical ages in planet formation and evolution, we measure the evolution of the GALEX NUV and FUV flux as a function of age. The median UV flux remains at a "saturated" level for a few hundred million years, analogous to that observed for X-ray emission. By the age of the Hyades Cluster (650 Myr), we measure a drop in UV flux by a factor of 2-3 followed by a steep drop from old (several Gyrs) field stars. This decline in activity beyond 300 Myr follows roughly t-1. Despite this clear evolution, there remains a wide range, of 1-2 orders of magnitude, in observed emission levels at every age. These UV data supply the much-needed constraints to M dwarf upper-atmosphere models, which will provide empirically motivated EUV predictions and more accurate age-dependent UV spectra as inputs to planetary photochemical models. © 2014. The American Astronomical Society. All rights reserved.
Scheller M.,University of Arizona
Journal of Infrared, Millimeter, and Terahertz Waves | Year: 2014
The potential of terahertz (THz) time domain spectroscopy to simultaneously determine the complex dielectric parameters of materials and their geometrical thickness is of high interest for scientific spectroscopy and for general metrology. This paper provides an overview of the background of the data extraction from THz measurements and discusses the accuracy and ambiguity of this extraction process. It is shown that the signal to noise ratio of the measurement as well as the bandwidth of the accessible THz spectrum define the limitation of the achievable accuracy in the data extraction. © 2014 Springer Science+Business Media New York.
Quam C.,University of Arizona |
Swingley D.,University of Pennsylvania
Child Development | Year: 2012
Young infants respond to positive and negative speech prosody (A. Fernald, 1993), yet 4-year-olds rely on lexical information when it conflicts with paralinguistic cues to approval or disapproval (M. Friend, 2003). This article explores this surprising phenomenon, testing one hundred eighteen 2- to 5-year-olds' use of isolated pitch cues to emotions in interactive tasks. Only 4- to 5-year-olds consistently interpreted exaggerated, stereotypically happy or sad pitch contours as evidence that a puppet had succeeded or failed to find his toy (Experiment 1) or was happy or sad (Experiments 2, 3). Two- and 3-year-olds exploited facial and body-language cues in the same task. The authors discuss the implications of this late-developing use of pitch cues to emotions, relating them to other functions of pitch. © 2011 The Authors. Child Development © 2011 Society for Research in Child Development, Inc.
Donoghue M.J.,Yale University |
Sanderson M.J.,University of Arizona
New Phytologist | Year: 2015
We review the empirical phylogenetic literature on plant diversification, highlighting challenges in separating the effects of speciation and extinction, in specifying diversification mechanisms, and in making convincing arguments. In recent discussions of context dependence, key opportunities and landscapes, and indirect effects and lag times, we see a distinct shift away from single-point/single-cause 'key innovation' hypotheses toward more nuanced explanations involving multiple interacting causal agents assembled step-wise through a tree. To help crystalize this emerging perspective we introduce the term 'synnovation' (a hybrid of 'synergy' and 'innovation') for an interacting combination of traits with a particular consequence ('key synnovation' in the case of increased diversification rate), and the term 'confluence' for the sequential coming together of a set of traits (innovations and synnovations), environmental changes, and geographic movements along the branches of a phylogenetic tree. We illustrate these concepts using the radiation of Bromeliaceae. We also highlight the generality of these ideas by considering how rate heterogeneity associated with a confluence relates to the existence of particularly species-poor lineages, or 'depauperons.' Many challenges are posed by this re-purposed research framework, including difficulties associated with partial taxon sampling, uncertainty in divergence time estimation, and extinction. © 2015 New Phytologist Trust.
Monoclonal gammopathy of undetermined significance and smoldering multiple myeloma: A review of the current understanding of epidemiology, biology, risk stratification, and management of myeloma precursor disease
Agarwal A.,University of Arizona |
Ghobrial I.M.,Dana-Farber Cancer Institute
Clinical Cancer Research | Year: 2013
The term monoclonal gammopathy of undetermined significance (MGUS) was coined in 1978. The recent advances in our knowledge about MGUS and smoldering multiple myeloma (SMM) have helped us better understand the pathogenesis of myeloma. It seems that myeloma evolves from a precursor state in almost all cases. We do not completely understand the multistep process from the precursor state to myeloma, but studies like whole genome sequencing continue to improve our understanding of this process. The process of transformation may not be linear acquisition of changes, but rather a branched heterogeneous process. Clinical features that are prognostic of rapid transformation have been identified, but no specific molecular markers have been identified. Even with recent advances, multiple myeloma remains an incurable disease in the vast majority, and intervening at the precursor state provides a unique opportunity to alter the natural history of the disease. A limitation is that a vast majority of patients with precursor disease, especially low-risk MGUS, will never progress to myeloma in their lifetime, and treating these patients is not only unnecessary but may be potentially harmful. The challenge is to identify a subset of patients with the precursor state that would definitely progress to myeloma and in whom interventions will have a meaningful impact. As our understanding of the molecular and genetic processes improves, these studies will guide the selection of high-risk patients more appropriately and ultimately direct a tailored management strategy to either delay progression to symptomatic myeloma or even "cure" a person at this premalignant stage. © 2012 American Association for Cancer Research.
Kubal W.S.,University of Arizona
Radiologic Clinics of North America | Year: 2012
Computed tomography (CT) and magnetic resonance (MR) play important roles in the evaluation of traumatic brain injury. Modern CT scanners allow for rapid and accurate diagnosis of intracranial hemorrhage and mass effect and allow the efficient implementation of emergent CT angiography. Newer sequences, such as gradient recalled echo, susceptibility-weighted imaging, and diffusion-weighted imaging, can provide greater sensitivity for specific types of diffuse posttraumatic brain injury. MR spectroscopy can provide additional chemical information, and diffusion tensor imaging can provide information about white matter injury. Patient treatment can be optimized using the diagnostic and prognostic information derived from current imaging techniques. © 2012 Elsevier Inc.
Cohen A.S.,University of Arizona
Hydrobiologia | Year: 2012
Scientific drilling to recover sediment core and fossil samples is a promising approach to increasing our understanding of species evolution in ancient lakes. Most lake drilling efforts to date have focused on paleoclimate reconstruction. However, it is clear from the excellent fossil preservation and high temporal resolution typical of lake beds that significant advances in evolutionary biology can be made through drill core studies coordinated with phylogenetic work on appropriate taxa. Geological records can be used to constrain the age of specific lakes and the timing of evolutionarily significant events (such as lake level fluctuations and salinity crises). Fossil data can be used to test speciation and biogeographic hypotheses and flesh out phylogenetic trees, using a better-resolved fossil record to estimate timing of phylogenetic divergences. The extraordinary preservation of many fossils in anoxic lake beds holds the hope of collecting fossil DNA from the same body fossils that improve our understanding of morphological character evolution and adaptation. Moreover, fossils allow calibration of molecular clocks, which are currently largely inferential. Lake Malawi Drilling Project results provide some guideposts on what might be expected in a drilling project for studies of evolution. The extreme variability in lake level and environmental history that most ancient lakes experience (exemplified by the Lake Malawi record) demonstrates that no one drilling locality is likely to provide a complete record of phylogenetic history for a radiating lineage. Evolutionary biologists should take an active role in the design of drilling projects, which typically have interdisciplinary objectives, to ensure their sampling needs will be met by whatever sites in a lake are ultimately drilled. © 2011 Springer Science+Business Media B.V.
Pelletier J.D.,University of Arizona
Journal of Geophysical Research: Earth Surface | Year: 2012
Understanding and quantifying the long-term suspended sediment discharge of drainage basins is a key goal of geomorphology, with important implications for the study of water quality, agricultural sustainability, and the evolution of landscapes and sedimentary basins over geologic timescales. Previous studies have highlighted the importance of relief/slope, precipitation, temperature, vegetation, and soil texture in controlling suspended sediment discharge in natural/undisturbed landscapes. However, globally applicable models currently used to predict suspended sediment discharges are limited because they are based on basin-averaged versions of these properties and do not incorporate all of the controlling variables into a single model. In this paper, I propose a spatially distributed, globally applicable model for the long-term suspended sediment discharge of drainage basins that includes all of the principal controls on suspended sediment discharge previously documented in the geomorphic literature. The model explicitly distinguishes the detachment of sediment on hillslopes and in low-order valleys from the transport of sediment in higher-order alluvial channels. The model uses slope, soil texture, mean monthly rainfall, and mean monthly leaf area index as controlling parameters for the detachment component. The transport component is modeled using a Rouse number-dependent transport criterion that explicitly includes the effects of slope and soil texture. The model is capable of reproducing the long-term sediment yield of 128 global rivers with a Pearson correlation coefficient (R value) of 0.79 using just two free parameters. The model also predicts sediment delivery ratios consistent with those measured in natural drainage basins. Copyright 2012 by the American Geophysical Union.
Saavedra S.S.,University of Arizona
Advances in Polymer Science | Year: 2010
Potential technological applications for artificial lipid and proteo-lipid membranes, such as capsules for controlled delivery of drugs and coatings for biosensors and biomaterials, are in many cases limited by the inherent instability of lipid lamellar phases. Development of methods to stabilize artificial lipid membranes has therefore been a focus of research efforts since the 1970s. Linear and cross-linking polymerization of synthetic lipid monomers is a well-studied strategy. Several comprehensive reviews on polymerizable lipids and supramolecular structures derived from them appeared between 1985 and 2002. Consequently, this review focuses on significant developments in this field during 2000-2008. These include synthesis of new types of polymerizable lipids, creation and characterization of novel poly(lipid) membrane systems, and applications of polymerized vesicles and membranes in chemical sensing, separations science, drug delivery, materials biocompatibility, and energy storage. Polymerization of membranes to achieve stability and their functionalization for technological applications are emphasized. © 2009 Springer-Verlag Berlin Heidelberg.
Gonzales R.J.,University of Arizona
Pflugers Archiv European Journal of Physiology | Year: 2013
Sex steroids are commonly known for their contribution to phenotypic as well as biological reproductive sex differences mediated through classical regulation of neuroendocrine loops. However, sex steroids also have considerable impact on physiological function of non-reproductive tissues including the cerebrovasculature. Preclinical studies have shown that endogenous and exogenous administration of sex steroids significantly influences both cerebrovascular tone and brain function under normal conditions and following a pathological insult (e.g., middle cerebral artery occlusion). However, the precise mechanism(s) of how sex steroids modulate vasomotor responses and/or neurological outcomes in vivo is difficult to define since evidence based on both clinical and experimental studies has been shown to be dependent upon several variables including dose, duration of administration, presence of underlying pathologies, species, and sex. While progesterone, testosterone (TEST), and dihydrotestosterone (DHT) have all been investigated for their impact on the cerebral circulation, the effects of 17β-estradiol (E2) have been best characterized. Since recent reviews have highlighted studies reporting the actions of E2 on cerebral vascular function and health, only key points are included in this review. Conversely, less is known about the effect of androgens on the blood vessel wall, particularly in the cerebral circulation. The few studies that do address a role for androgen's modulation of cerebrovascular function under normal and pathophysiological conditions provide confounding evidence for either beneficial or detrimental effects. Therefore, the focus of this review is to highlight mechanisms associated with TEST, DHT, and its recently recognized androgen metabolite (3β-diol) on cerebrovascular function during healthy and diseased states. © 2013 Springer-Verlag Berlin Heidelberg.
Ercolani N.M.,University of Arizona
Nonlinearity | Year: 2011
This paper develops a deeper understanding of the structure and combinatorial significance of the partition function for Hermitian random matrices. The coefficients of the large N expansion of the logarithm of this partition function, also known as the genus expansion (and its derivatives), are generating functions for avariety of graphical enumeration problems. The main results are to prove that these generating functions are,in fact, specific rational functions of a distinguished irrational (algebraic) function, z 0(t). This distinguished function is itself the generating function for the Catalan numbers (or generalized Catalan numbers, depending on the choice of weight of the parameter t ). It is also a solution of the inviscid Burgers equation for certain initial data. The shock formation, or caustic, of the Burgers characteristic solution is directly related to the poles of the rational forms of the generating functions. As an intriguing application, one gains new insights into the relation between certain derivatives of the genus expansion, in a double-scaling limit, and the asymptotic expansion of the first Painlevé transcendent. This provides a precise expression of the Painlevé asymptotic coefficients directly in terms of the coefficients of the partial fractions expansionof the rational form of the generating functions established in this paper. Moreover, these insights point towards a more general program relating the first Painlevé hierarchy to the higher order structure of the double-scaling limit through the specific rational structure of generating functions in the genus expansion. The paper closes with a discussion of the relation of this work to recent developments in understanding the asymptotics of graphical enumeration. As a by-product, these results also yield new information about the asymptotics of recurrence coefficients for orthogonal polynomials with respect to exponential weights, the calculation of correlation functions for certain tied. © 2011 IOP Publishing Ltd and London Mathematical Society.
Sasian J.,University of Arizona
Applied Optics | Year: 2010
A sixth-order theory of wave aberrations for axially symmetric systems is developed. Specific formulas for the sixth-order extrinsic and intrinsic wave aberration coefficients are given, as well as relations between pupil and image aberrations. Equations are developed for the wavefront propagation to the sixth order of approximation. The concept of the irradiance function is developed, and the second-order irradiance coefficients are found via conservation of flux at the pupils of the optical system and in terms of pupil aberrations. From purely geometrical considerations a generalized irradiance transport equation that describes irradiance changes in an optical system is derived. Confirming the aberration coefficients with real raytracing data was found to be indispensable. © 2010 Optical Society of America.
Djordjevic I.B.,University of Arizona
Optics Letters | Year: 2010
I propose encoder and decoder architectures for entanglement-assisted (EA) quantum low-density paritycheck (LDPC) codes suitable for all-optical implementation. I show that two basic gates needed for EA quantum error correction, namely, controlled-NOT (CNOT) and Hadamard gates can be implemented based on Mach-Zehnder interferometer. In addition, I show that EA quantum LDPC codes from balanced incomplete block designs of unitary index require only one entanglement qubit to be shared between source and destination. © 2010 Optical Society of America.
Scott C.A.,University of Arizona
Environmental Research Letters | Year: 2013
Globally, groundwater use is intensifying to meet demands for irrigation, urban supply, industrialization, and, in some instances, electrical power generation. In response to hydroclimatic variability, surface water is being substituted with groundwater, which must be viewed as a strategic resource for climate adaptation. In this sense, the supply of electricity for pumping is an adaptation policy tool. Additionally, planning for climate-change mitigation must consider CO2 emissions resulting from pumping. This paper examines the influence of electricity supply and pricing on groundwater irrigation and resulting emissions, with specific reference to Mexico - a climate-water-energy 'perfect storm'. Night-time power supply at tariffs below the already-subsidized rates for agricultural groundwater use has caused Mexican farmers to increase pumping, reversing important water and electricity conservation gains achieved. Indiscriminate groundwater pumping, including for virtual water exports of agricultural produce, threatens the long-term sustainability of aquifers, non-agricultural water uses, and stream-aquifer interactions that sustain riparian ecosystems. Emissions resulting from agricultural groundwater pumping in Mexico are estimated to be 3.6% of total national emissions and are equivalent to emissions from transporting the same agricultural produce to market. The paper concludes with an assessment of energy, water, and climate trends coupled with policy futures to address these challenges. © 2013 IOP Publishing Ltd.
Fregosi R.F.,University of Arizona
Journal of Applied Physiology | Year: 2011
The mammalian pharynx is a hollow muscular tube that participates in ingestion and respiration, and its size, shape, and stiffness can be altered by contraction of skeletal muscles that lie inside or outside of its walls. MRI was used to determine the interaction between pharyngeal pressure and selective stimulation of extrinsic tongue muscles on the shape of the rat nasopharynx. Pressure (-9, -6, -3, 3, 6, and 9 cmH 2O) was applied randomly to the isolated pharyngeal airway of anesthetized rats that were positioned in a 4.7-T MRI scanner. The anterior-posterior (AP) and lateral diameters of the nasopharynx were measured in eight axial slices at each level of pressure, with and without bilateral hypoglossal nerve stimulation (0.1-ms pulse, 1/3 maximal force, 80 Hz). The rat nasopharynx is nearly circular, and positive pharyngeal pressure caused similar expansion of AP and lateral diameters; as a result, airway shape (ratio of lateral to AP diameter) remained constant. Negative pressure did not change AP or lateral diameter significantly, suggesting that a negative pressure reflex activated the tongue or other pharyngeal muscles. Stimulation of tongue protrudor muscles alone or coactivation of protrudor and retractor muscles caused greater AP than lateral expansion, making the nasopharynx slightly more elliptical, with the long axis in the AP direction. These effects tended to be more pronounced at negative pharyngeal pressures and greater in the caudal than rostral nasopharynx. These data show that stimulation of rodent tongue muscles can adjust pharyngeal shape, extending previous work showing that tongue muscle contraction alters pharyngeal compliance and volume, and provide physiological insight that can be applied to the treatment of obstructive sleep apnea. © 2011 by the American Physiological Society.
Xiao M.,University of Arizona
International Journal of Industrial Organization | Year: 2010
The ineffectiveness of a quality accreditation mechanism can be attributed to the inability of the accreditation status to provide consumers with information they do not already possess. I present a structural model of demand allowing consumers to infer quality from both accreditation status and firm reputation. I then estimate this model to assess the effectiveness and the impact of the national accreditation system for childcare centers on consumer welfare. My results suggest that disregarding the endogeneity of firms' accreditation choices significantly underestimates the effectiveness of the accreditation system. However, on average consumers do not gain much information beyond what they have inferred from a firm's reputation. The estimates of structural parameters are then used to quantify the value of this information to consumers. © 2010 Elsevier B.V.
Hameroff S.,University of Arizona
Journal of Biological Physics | Year: 2010
Cognitive brain functions including sensory processing and control of behavior are understood as "neurocomputation" in axonal-dendritic synaptic networks of "integrate-and-fire" neurons. Cognitive neurocomputation with consciousness is accompanied by 30- to 90-Hz gamma synchrony electroencephalography (EEG), and non-conscious neurocomputation is not. Gamma synchrony EEG derives largely from neuronal groups linked by dendritic-dendritic gap junctions, forming transient syncytia ("dendritic webs") in input/integration layers oriented sideways to axonal-dendritic neurocomputational flow. As gap junctions open and close, a gamma-synchronized dendritic web can rapidly change topology and move through the brain as a spatiotemporal envelope performing collective integration and volitional choices correlating with consciousness. The "conscious pilot" is a metaphorical description for a mobile gamma-synchronized dendritic web as vehicle for a conscious agent/pilot which experiences and assumes control of otherwise non-conscious auto-pilot neurocomputation.
Marks B.,University of Arizona
Journal of Agrarian Change | Year: 2012
The Louisiana shrimp fishery is marked by the ownership and operation of vessels by familial households, an open-access management regime, and socially embedded inter-firm relationships among shrimpers, docks and processors. These elements of the contemporary fishery were constituted through historically and geographically specific processes of change in harvesting and processing technology, the social organization of labour processes and market exchanges, and the politics of fishery management in the state. These processes shaped producers' responses to a severe socio-economic crisis in the 2000s, a cost-price squeeze of collapsing shrimp prices and mounting production expenses. Shrimpers' households kept boats operating in the short term at the expense of living standards and intergenerational continuity, rising fuel prices and falling shrimp prices slashed shrimpers' income from harvesting wild shrimp, and business relations grew more distant, tenuous and conflictual as enterprises each sought their share of a much smaller surplus. © 2012 Blackwell Publishing Ltd.
Pelletier J.D.,University of Arizona
Earth Surface Processes and Landforms | Year: 2012
Many numerical landform evolution models assume that soil erosion by flowing water is either purely detachment-limited (i.e. erosion rate is related to the shear stress, power, or velocity of the flow) or purely transport-limited (i.e. erosion/deposition rate is related to the divergence of shear stress, power, or velocity). This paper reviews available data on the relative importance of detachment-limited versus transport-limited erosion by flowing water on soil-mantled hillslopes and low-order valleys. Field measurements indicate that fluvial and slope-wash modification of soil-mantled landscapes is best represented by a combination of transport-limited and detachment-limited conditions with the relative importance of each approximately equal to the ratio of sand and rock fragments to silt and clay in the eroding soil. Available data also indicate that detachment/entrainment thresholds are highly variable in space and time in many landscapes, with local threshold values dependent on vegetation cover, rock-fragment armoring, surface roughness, soil texture and cohesion. This heterogeneity is significant for determining the form of the fluvial/slope-wash erosion or transport law because spatial and/or temporal variations in detachment/entrainment thresholds can effectively increase the nonlinearity of the relationship between sediment transport and stream power. Results from landform evolution modeling also suggest that, aside from the presence of distributary channel networks and autogenic cut-and-fill cycles in non-steady-state transport-limited landscapes, it is difficult to infer the relative importance of transport-limited versus detachment-limited conditions using topography alone. © 2011 John Wiley & Sons, Ltd.
Fink U.,University of Arizona |
Rubin M.,University of Michigan
Icarus | Year: 2012
Ab initio calculations of Afρ are presented using Mie scattering theory and a Direct Simulation Monte Carlo (DSMC) dust outflow model in support of the Rosetta mission and its target 67P/. Churyumov-Gerasimenko (CG). These calculations are performed for particle sizes ranging from 0.010. μm to 1.0. cm. The present status of our knowledge of various differential particle size distributions is reviewed and a variety of particle size distributions is used to explore their effect on Afρ, and the dust mass production m A new simple two parameter particle size distribution that curtails the effect of particles below 1. μm is developed. The contributions of all particle sizes are summed to get a resulting overall Afρ. The resultant Afρ could not easily be predicted a priori and turned out to be considerably more constraining regarding the mass loss rate than expected. It is found that a proper calculation of Afρ combined with a good Afρ measurement can constrain the dust/gas ratio in the coma of comets as well as other methods presently available. Phase curves of Afρ versus scattering angle are calculated and produce good agreement with observational data.The major conclusions of our calculations are:. -The original definition of A in Afρ is problematical and Afρ should be: q sca(n, λ) × p(g) × f × ρ.Nevertheless, we keep the present nomenclature of Afρ as a measured quantity for an ensemble of coma particles.-The ratio between Afρ and the dust mass loss rate m is dominated by the particle size distribution.-For most particle size distributions presently in use, small particles in the range from 0.10 to 1.0μm contribute a large fraction to Afρ.-Simplifying the calculation of Afρ by considering only large particles and approximating q sca does not represent a realistic model. Mie scattering theory or if necessary, more complex scattering calculations must be used.-For the commonly used particle size distribution, dn/da∼a -3.5 to a -4, there is a natural cut off in Afρ contribution for both small and large particles.-The scattering phase function must be taken into account for each particle size; otherwise the contribution of large particles can be over-estimated by a factor of 10.-Using an imaginary index of refraction of i=0.10 does not produce sufficient backscattering to match observational data.-A mixture of dark particles with i0.10 and brighter silicate particles with i0.04 matches the observed phase curves quite well.-Using current observational constraints, we find the dust/gas mass-production ratio of CG at 1.3 AU is confined to a range of 0.03-0.5 with a reasonably likely value around 0.1. © 2012 Elsevier Inc.
Skodol A.E.,University of Arizona
Personality and Mental Health | Year: 2011
DSM-5 is scheduled for publication in 2013. The revision process will be the product of over 13years of work. DSM-5 Work Groups have recently proposed changes in each of the major diagnostic classes of mental disorders and revised their proposals in anticipation of APA-sponsored and APA-conducted Field Trials now underway. This article will review the scientific and philosophical principles guiding the revisions and how they have influenced the development of the proposed changes for the assessment and diagnosis of personality psychopathology for DSM-5. Included are discussions of the definition of mental disorder, dimensional vs. categorical approaches to diagnosis, criteria for change, validity vs. clinical utility, cultural applicability, the relationship of DSM-5 and ICD-11 and diagnosis for specialty vs. primary care settings. Although principles for revising the DSM-5 were articulated some time ago, the revision process thus far has proceeded with some degree of ambiguity, controversy and contradiction. © 2011 American Psychiatric Association.
Koss M.P.,University of Arizona
Journal of Interpersonal Violence | Year: 2014
The article reports empirical evaluation of RESTORE, a restorative justice (RJ) conferencing program adapted to prosecutor-referred adult misdemeanor and felony sexual assaults. RESTORE conferences included voluntary enrollment, preparation, and a face-to-face meeting where primary and secondary victims voice impacts, and responsible persons acknowledge their acts and together develop a re-dress plan that is supervised for 1 year. Process data included referral and consent rates, participant characteristics, observational ratings of conferences compared with program design, services delivered, and safety monitoring. Outcome evaluation used 22 cases to assess (a) pre-post reasons for choosing RESTORE, (b) preparation and conference experiences, (c) overall program and justice satisfaction, and (d) completion rates. This is the first peer-reviewed quantitative evaluation of RJ conferencing for adult sexual assault. Although the data have limitations, the results support cautious optimism regarding feasibility, safety, and satisfactory outcomes. They help envision how conferencing could expand and individualize justice options for sexual assault. © The Author(s) 2013.
Bronstein J.L.,University of Arizona
Molecular Ecology | Year: 2013
Mutualisms, cooperative interactions between species, generally involve an economic exchange: species exchange commodities that are cheap for them to provide, for ones that cannot be obtained affordably or at all. But these associations can only succeed if effective partners can be enticed to interact. In some mutualisms, partners can actively seek one another out. However, plants, which use mutualists for a wide array of essential life history functions, do not have this option. Instead, natural selection has repeatedly favoured the evolution of rewards - nutritional substances (such as sugar-rich nectar and fleshy fruit) with which plants attract certain organisms whose feeding activities can then be co-opted for their own benefit. The trouble with rewards, however, is that they are usually also attractive to organisms that confer no benefits at all. Losing rewards to 'exploiters' makes a plant immediately less attractive to the mutualists it requires; if the reward cannot be renewed quickly (or at all), then mutualistic service is precluded entirely. Thus, it is in plants' interests to either restrict rewards to only the most beneficial partners or somehow punish or deter exploiters. Yet, at least in cases where the rewards are highly nutritious, we can expect counter-selection for exploiter traits that permit them to skirt such control. How, then, can mutualisms persist? In this issue, Orona-Tamayo et al. () describe a remarkable adaptation that safeguards one particularly costly reward from nonmutualists. Their study helps to explain the evolutionary success of an iconic interaction and illuminates one way in which mutualism as a whole can persist in the face of exploitation. © 2013 John Wiley & Sons Ltd.
Mansuripur M.,University of Arizona
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2011
We derive exact expressions, in the form of Fourier integrals over the (k,ω) domain, for the energy, momentum, and angular momentum of a light pulse propagating in free space. The angular momentum is seen to split naturally into two parts. The spin contribution of each plane-wave constituent of the pulse, representing the difference between its right- and left-circular polarization content, is aligned with the corresponding k-vector. In contrast, the orbital angular momentum associated with each plane-wave is orthogonal to its k-vector. In general, the orbital angular momentum content of the wavepacket is the sum of an intrinsic part, due, for example, to phase vorticity, and an extrinsic part, rCM × p, produced by the linear motion of the center-of-mass rCM of the light pulse in the direction of its linear momentum p. © 2011 American Physical Society.
Reiman E.M.,University of Arizona
Neurobiology of Aging | Year: 2011
Alzheimer's disease (AD) is associated with characteristic and progressive reductions in flourodeoxyglucose positron emission tomography (FDG PET) measurements of the regional cerebral metabolic rate for glucose. These reductions begin years before the onset of symptoms, are correlated with clinical severity, and may help predict an affected patient's clinical course and neuropathological diagnosis. Like several other AD biomarkers, FDG PET has the potential to accelerate the evaluation of AD-modifying treatments, particularly in the earliest clinical and preclinical stages. This article considers FDG PET's role in the detection and tracking of AD, its emerging roles in the evaluation of disease-slowing treatments, some of the issues involved in the acquisition, analysis, and interpretation of FDG PET data, and the evidence needed to help qualify FDG PET and other biomarkers for use in the accelerated approval of AD-slowing treatments. It recommends scientific strategies and public policies to further establish the role of FDG PET and other AD biomarkers in therapeutic trials and find demonstrably effective disease-modifying and presymptomatic AD treatments as quickly as possible. © 2011 Elsevier Inc.
Renner T.,University of Arizona |
Specht C.D.,University of California at Berkeley
Current Opinion in Plant Biology | Year: 2013
The digestion of prey by carnivorous plants is determined in part by suites of enzymes that are associated with morphologically and anatomically diverse trapping mechanisms. Chitinases represent a group of enzymes known to be integral to effective plant carnivory. In non-carnivorous plants, chitinases commonly act as pathogenesis-related proteins, which are either induced in response to insect herbivory and fungal elicitors, or constitutively expressed in tissues vulnerable to attack. In the Caryophyllales carnivorous plant lineage, multiple classes of chitinases are likely involved in both pathogenic response and digestion of prey items. We review what is currently known about trap morphologies, provide an examination of the diversity, roles, and evolution of chitinases, and examine how herbivore and pathogen defense mechanisms may have been coopted for plant carnivory in the Caryophyllales. © 2013.
Boyer L.,University of Arizona
Toxicon | Year: 2013
This paper was originally presented as the Elsevier Lecture in July, 2012 at the International Society on Toxinology/Venom Week combined meeting in Honolulu, Hawaii. In it, the author addresses the ancient history of venom and immunity, from the Silurian Era to the 1890s; the development of the first antivenoms; the impact of shifting political and economic pressures; the special case of Arizona; the relative stability of the 1960s through 1990s; the transition to regulatory compliance that took place at the time of the author's own research; and concluding thoughts regarding the instability of apparent success. © 2013 Elsevier Ltd.
Gelman I.A.,University of Arizona
Decision Support Systems | Year: 2010
This study introduces a mathematical-statistical theory that illustrates the effect of input errors on the accuracy of dichotomous decisions which are implemented through logical conjunction and disjunction of selected criteria. Decision-making instances in this category are often labeled "satisficing." Mainly, our theory provides criteria for ranking the effect of errors in different inputs on decision accuracy. This ranking can be used to improve the efficiency and effectiveness of resource allocation decisions in data quality management settings. All other things being equal, inputs in which errors exhibit a higher negative effect on the output would naturally earn higher priority. © 2009 Elsevier B.V. All rights reserved.
Smith N.,University of Arizona
Monthly Notices of the Royal Astronomical Society | Year: 2013
This paper proposes a simple model for the 19th century eruption of Eta Carinae that consists of two components: (1) a strong wind ( Ṁ = 0.33M· yr-1; v∞ = 200 km s-1), blowing for 30 yr, followed by (2) a 1050 erg explosion (10M·; 750-1000 km s-1) occurring in 1844. The ensuing collision between the fast ejecta and the dense circumstellar material (CSM) causes an increase in brightness observed at the end of 1844, followed by a sustained high-luminosity phase lasting for 10-15 yr that provides a close match to the observed historical light curve. The emergent luminosity is powered by converting kinetic energy to radiation through CSM interaction, analogous to the process occurring in more luminous Type IIn supernovae, except with ~10 times lower explosion energy and at slower speeds (causing a longer duration and lower emergent luminosity). We demonstrate that such an explosive event not only provides a natural explanation for the light-curve evolution, but also accounts for a number of puzzling attributes of the highly scrutinized Homunculus, including: (1) rough equipartition of total radiated and kinetic energy in the event, (2) the double-shell structure of the Homunculus, with a thin massive outer shell (corresponding to the coasting cold dense shell) and a thicker inner layer (between the cold dense shell and the reverse shock), (3) the apparent single age and Hubble-like flow of the Homunculus resulting from the thin swept-up shell, (4) the complex mottled appearance of the polar lobes in Hubble Space Telescope images, arising naturally from Raleigh-Taylor orVishniac instabilities at the contact discontinuity of the shock, (5) efficient and rapid dust formation, which has been observed in the post-shock zones of Type IIn supernovae, and (6) the fast (3000-5000 km s-1) material outside the Homunculus, arising from the acceleration of the forward shock upon exiting the dense CSM. In principle, the bipolar shape could be explained borrowing from earlier studies of interacting winds, except that here the requisite pre-existing 'torus' may be provided by periastron collisions occurring around the same time, and the CSM interaction occurs over only 10 yr, producing a thin shell with the resulting structures then frozen-in to a homologously expanding bipolar nebula. This self-consistent picture has a number of implications for other eruptive transients, many of which may also be powered by CSM interaction. A key remaining unknown is the ultimate source of the 1050 erg of energy required in the explosion. © 2012 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.
Dickinson W.R.,University of Arizona
Quaternary Research | Year: 2011
Discovery of the Monte Verde archeological site in Chile overturned the previous consensus that the first Americans into the New World from Asia were the makers of Clovis projectile points, and rejuvenated the hypothesis that migration through the Americas occurred largely on portions of the Pacific continental shelf exposed by Pleistocene drawdown in eustatic sea level. The postulate of travel along a paleoshoreline now hidden underwater is an attractive means to posit pre-Clovis human movement southward from Beringia to Chile without leaving traces of migration onshore. Geologic analyses of the Pleistocene paleoenvironment at Monte Verde and of the morphology of the potential migration route along the continental shelf raise questions that have not been fully addressed. The periglacial setting of Monte Verde may call its antiquity into question and the narrowness of the Pacific continental shelf of the Americas makes it unlikely that people could travel the length of the Americas without impacting ground still onshore and no farther inland than Monte Verde itself. Geological perspectives on Monte Verde and coastal migration jointly suggest that the Clovis-first hypothesis for peopling the New World may have been abandoned prematurely. © 2011 University of Washington.
Han Y.,University of Arizona
Information Technology and Libraries | Year: 2010
This article introduces cloud computing and discusses the author's experience "on the clouds." The author reviews cloud computing services and providers, then presents his experience of running multiple systems (e.g., integrated library systems, content management systems, and repository software). He evaluates costs, discusses advantages, and addresses some issues about cloud computing. Cloud computing fundamentally changes the ways institutions and companies manage their computing needs. Libraries can take advantage of cloud computing to start an IT project with low cost, to manage computing resources cost-effectively, and to explore new computing possibilities.
Sanfelice R.G.,University of Arizona
IEEE Transactions on Automatic Control | Year: 2013
For a class of hybrid systems given in terms of constrained differential and difference equations/inclusions, we study the existence of control Lyapunov functions when compact sets are asymptotically stable as well as the stabilizability properties guaranteed when control Lyapunov functions exist. An existence result asserting that asymptotic stabilizability of a compact set implies the existence of a smooth control Lyapunov function is established. When control Lyapunov functions are available, conditions guaranteeing the existence of stabilizing continuous state-feedback control laws are provided. © 1963-2013 IEEE.
Hubbard W.B.,University of Arizona
Astrophysical Journal Letters | Year: 2012
We present an efficient numerical self-consistent field method for calculating a gravitational model of a rotating liquid planet to spherical harmonic degree ∼30 and a precision ∼10-12 in the external gravity field. The method's accuracy is validated by comparing results, for Jupiter rotation parameters, with the exact Maclaurin constant-density solution. The method can be generalized to non-constant density. © © 2012. The American Astronomical Society. All rights reserved.
Girardeau M.D.,University of Arizona
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2011
A harmonically trapped, ultracold, one-dimensional (1D) spin-1 Bose gas with strongly repulsive or attractive 1D even-wave interactions induced by a three-dimensional (3D) Feshbach resonance is studied. The exact ground state, a hybrid of Tonks-Girardeau (TG) and ideal Fermi gases, is constructed in the TG limit of infinite even-wave repulsion by a spinor Fermi-Bose mapping to a spinless ideal Fermi gas. It is then shown that in the limit of infinite even-wave attraction this same state remains an exact many-body eigenstate, now highly excited relative to the collapsed generalized McGuire-cluster ground state, showing that the hybrid TG state is completely stable against collapse to this cluster ground state under a sudden switch from infinite repulsion to infinite attraction. It is shown to be the TG limit of a hybrid super-Tonks-Girardeau (STG) state, which is metastable under a sudden switch from finite but very strong repulsion to finite but very strong attraction. It should be possible to create it experimentally by a sudden switch from strongly repulsive to strongly attractive interaction, as in the recent Innsbruck experiment on a spin-polarized bosonic STG gas. In the case of strong attraction, there should also exist another STG state of much lower energy, consisting of strongly bound dimers, a bosonic analog of a recently predicted STG state which is an ultracold gas of strongly bound bosonic dimers of fermionic atoms, but it is shown that this STG state cannot be created by such a switch from strong repulsion to strong attraction. © 2011 The American Physical Society.
Henry A.D.,University of Arizona |
Vollan B.,University of Innsbruck
Annual Review of Environment and Resources | Year: 2014
Network concepts are central to at least three challenges of interest in the sustainability science literature: how to link knowledge with action, how to enhance collective action, and how to promote social learning. Although each challenge has developed into a coherent literature, social network concepts - which examine the particular ways in which social agents relate to one another - emerge as a common theme across all three challenges. To build a synthetic understanding of networks and sustainability, we must consider how structural properties of networks relate to sustainability outcomes, how networks evolve over time, and how institutional context influences this evolutionary process. A better understanding of these questions can inform strategies to promote patterns of social interaction that support sustainability. Copyright © 2014 by Annual Reviews. All rights reserved.
Goes P.B.,University of Arizona
MIS Quarterly: Management Information Systems | Year: 2014
Paulo B. Goes, Editor-in-Chief, MIS Quarterly, discusses some of the articles related to design science research in top information systems journals. In 2004, the paper 'Design Science in Information Systems Research,' coauthored by Al Hevner, Sal March, Sudha Ram was published in MIS Quarterly. One of the main points of the Hevner and co-researchers'paper is to contrast the design science paradigm with the behavioral sciences paradigm. Following the 2004 design science article, there was a Special Issue on Design Science in MISQ, which published five articles in 2008. A design science artifact is created against the background of the descriptive knowledge about the problem domain (artificial, natural, human) and its laws, regularities, principles, and theories. The artifact itself encompasses and produces knowledge as constructs, models, methods, and instantiations that may or may not lead to the level of abstraction that constitutes a design theory. While design science research is widely recognized as one of the main paradigms of IS research, it has not experienced much publication success in a journal like MISQ. The main reason is that design science researchers are not submitting their work to the top tier journals in the IS discipline.
Greenberg R.,University of Arizona
Astrobiology | Year: 2010
Bombardment of the surface of Europa produces oxidants and other biologically useful substances, but they can only contribute to the habitability of the ocean if they are delivered down through the icy crust. Previous estimates of the thickness of the oxygenated layer of ice assumed that impact gardening is the dominant factor and concluded that the ocean may be habitable if the oxidant delivery time, via undefined mechanisms, is sufficiently short. Consideration of the types of processes that continually resurface Europa suggests that the oxygenated layer is thicker than ̃300m, far greater than the few meters indicated by impact gardening alone, and possibly includes the entire ice crust. The estimated delivery rate to the ocean is such that the oxygen levels could now be high enough to support macrofauna; and, at ̃31011mol/yr of oxygen, it could maintain 3 million tons of macrofauna, assuming respiration rates similar to terrestrial marine organisms. These values are independent of any additional contributions due to possible photosynthesis. Initial formation of life would be difficult with so much oxygen, but the start of oxidant delivery into the ocean would have been delayed by 1-2 billion years while the crust became loaded with oxidants. In the ocean, this delay would have allowed time for prebiotic assemblages and anaerobic biological development prior to the increasing oxidant concentration to otherwise toxic levels. Copyright 2010, Mary Ann Liebert, Inc.
Shaw I.G.R.,University of Arizona
Transactions of the Institute of British Geographers | Year: 2010
This paper argues for the political importance of Alain Badiou's 'site' in human geography. A site is a place of radical politics capable of destroying old worlds and creating new ones. Badiou's recently published Logics of worlds (2009, Continuum, London) is an account of how worlds come to exist. Critical to understanding this work is Badiou's critique of 'democratic materialism', an umbrella term used for Deleuzian and postmodern philosophies, defined by the phrase: 'there are only bodies and languages'. Badiou counters this with his 'materialist dialectic', which emphasises the intervention truth can make in a world: 'there are only bodies and languages, except that there are truths'. The subversion of the appearance of a world by the infinite potential of the site is cast as the emergence of a truth. Current theorisations of the site in human geography do not take into account truth as a political category. The paper is thus a defence of the site as an exceptional place of politics, where the materialist dialectic conviction: 'except that there are truths' is rendered visible.1. © 2010 The Author. Journal compilation © Royal Geographical Society (with The Institute of British Geographers) 2010.
Birky Jr. C.W.,University of Arizona
Trends in Parasitology | Year: 2010
Although Giardia is of practical importance as a pathogen and has theoretical importance in evolutionary biology, it is not known whether it ever reproduces sexually. Several recent papers have shed light on this problem, without completely solving it. One paper shows that nuclei in the encysted organism can temporarily fuse and exchange genes; this may explain the genetic similarity of the two nuclei in a cell. Another paper demonstrates that Giardia does undergo sexual reproduction with outcrossing. However, we still do not know whether this involves a meiotic or a parasexual cycle, when it occurs, or how common it is. © 2009 Elsevier Ltd. All rights reserved.
Ganapol B.D.,University of Arizona
Annals of Nuclear Energy | Year: 2013
Attempts to resolve the point kinetics equations (PKEs) describing nuclear reactor transients have been the subject of numerous articles and texts over the past 50 years. Some very innovative methods, such as the RTS (Reactor Transient Simulation) and CAC (Continuous Analytical Continuation) methods of G.R. Keepin and J. Vigil respectively, have been shown to be exceptionally useful. Recently however, several authors have developed methods they consider accurate without a clear basis for their assertion. In response, this presentation will establish a definitive set of benchmarks to enable those developing PKE methods to truthfully assess the degree of accuracy of their methods. Then, with these benchmarks, two recently published methods, found in this journal will be shown to be less accurate than claimed and a legacy method from 1984 will be confirmed. © 2012 Elsevier Ltd. All rights reserved.
Mansuripur M.,University of Arizona
Optics Communications | Year: 2011
Starting with the most general form of Maxwell's macroscopic equations in which the free charge and free current densities, ρfree and Jfree, as well as the densities of polarization and magnetization, P and M, are arbitrary functions of space and time, we compare and contrast two versions of the Poynting vector, namely, S = μo- 1E × B and S = E × H. Here E is the electric field, H is the magnetic field, B is the magnetic induction, and μo is the permeability of free space. We argue that the identification of one or the other of these Poynting vectors with the rate of flow of electromagnetic energy is intimately tied to the nature of magnetic dipoles and the way in which these dipoles exchange energy with the electromagnetic field. In addition, the manifest nature of both electric and magnetic dipoles in their interactions with the electromagnetic field has consequences for the Lorentz law of force. If the conventional identification of magnetic dipoles with Amperian current loops is extended beyond Maxwell's macroscopic equations to the domain where energy, force, torque, momentum, and angular momentum are active participants, it will be shown that "hidden energy" and "hidden momentum" become inescapable consequences of such identification with Amperian current loops. Hidden energy and hidden momentum can be avoided, however, if we adopt S = E × H as the true Poynting vector, and also accept a generalized version of the Lorentz force law. We conclude that the identification of magnetic dipoles with Amperian current loops, while certainly acceptable within the confines of Maxwell's macroscopic equations, is inadequate and leads to complications when considering energy, force, torque, momentum, and angular momentum in electromagnetic systems that involve the interaction of fields and matter. © 2010 Elsevier B.V. All rights reserved.
Arnold S.J.,University of Arizona |
Dugger B.N.,Santa Fe Institute |
Beach T.G.,Santa Fe Institute
Acta Neuropathologica | Year: 2013
TAR DNA-binding protein 43 (TDP-43) has been heavily researched in recent years due to its involvement in amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration. Several studies have also sought to investigate the frequency of TDP-43 deposition in other neurodegenerative diseases such as Alzheimer's and Parkinson's diseases, but there has been relatively little work focused on the prevalence, distribution and histopathological associations of abnormal TDP-43 deposits in the brains of cognitively normal elderly subjects. We screened thick, free-floating coronal sections of mesial temporal lobe from 110 prospectively followed and autopsied cognitively normal subjects (age range 71-100 years) using an immunohistochemical method for phosphorylated TDP-43. We found a 36.4 % prevalence of pathologic TDP-43, mostly in the form of neurites while perikaryal cytoplasmic neuronal inclusions were uncommon and intranuclear inclusions were rare. With respect to other concomitant pathologies commonly found in elderly individuals, cases with TDP-43 had a greater prevalence of argyrophilic grains (ARG) (40 vs. 18.6 %) and overall ARG density (moderate vs. sparse). There were no additional associations with other concomitant pathologies, including cerebral white matter rarefaction, incidental Lewy bodies, neurofibrillary tangles or amyloid plaques. These results indicate deposition of TDP-43 occurs in a substantial subset of cognitively normal elderly subjects and is more common in those with ARG, supporting some previous studies linking pathological TDP-43 deposition with ARG and other pathological tau protein deposits. © 2013 Springer-Verlag Berlin Heidelberg.
Jin P.,Broadcom Corporation |
Ziolkowski R.W.,University of Arizona
IEEE Transactions on Antennas and Propagation | Year: 2011
Several metamaterial-inspired, electrically small, near-field resonant parasitic antennas are presented. Both electric and magnetic couplings to the parasitic are compared and contrasted. The electric-coupled versions are shown to be more efficient and to have more bandwidth. The evolution of circular polarized designs from their linear counterparts by introducing multiple parasitics having different resonant frequencies is demonstrated. Single L1 and dual band L1/L2 GPS systems are emphasized for practical illustrations of the resulting performance characteristics. Preliminary experimental results for a dual band, circularly polarized GPS L1/L2 antenna are provided and underscore several practical aspects of these designs. © 2011 IEEE.
Pyun J.,University of Arizona |
Pyun J.,Seoul National University
Angewandte Chemie - International Edition | Year: 2012
No, it's not frogspawn! Polymer-coated gold nanoparticles can be assembled into extended mesoscopic chains with precise dimensional control. Here, the conditions can be adjusted to promote the fusion of polymeric ligands into cylindrical micellar aggregates. This type of colloidal polymerization offers a new and versatile route to a variety of mesoscopic assemblies of nanoparticles. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Kodi A.K.,Ohio University |
Louri A.,University of Arizona
IEEE Journal on Selected Topics in Quantum Electronics | Year: 2011
Optical interconnects are becoming ubiquitous for short-range communication within boards and racks due to higher communication bandwidth at lower power dissipation when compared to metallic interconnects. Efficient multiplexing techniques (wavelengths, time, and space) allow bandwidths to scale; static or predetermined resource allocation of wavelengths can be detrimental to network performance for nonuniform (adversial) workloads. Dynamic bandwidth reallocation (DBR) based on actual traffic pattern can lead to improved network performance by utilizing idle resources. While DBR techniques can alleviate interconnection bottlenecks, power consumption also increases considerably with increase in bit rate and channels. In this paper, we propose to improve the performance of optical interconnects using DBR techniques and simultaneously optimize the power consumption using dynamic power management (DPM) techniques. DBR reallocates idle channels to busy channels (wavelengths) for improving throughput, and DPM regulates the bit rates and supply voltages for the individual channels. A reconfigurable optoelectronic architecture and a performance adaptive algorithm for implementing DBR and DPM are proposed in this paper. Our proposed reconfiguration algorithm achieves a significant reduction in power consumption and considerable improvement in throughput, with a marginal increase in latency for synthetic and real (Splash-2) traffic traces. © 2010 IEEE.
Newell A.C.,University of Arizona |
Rumpf B.,TU Chemnitz
Annual Review of Fluid Mechanics | Year: 2011
In this article, we state and review the premises on which a successful asymptotic closure of the moment equations of wave turbulence is based, describe how and why this closure obtains, and examine the nature of solutions of the kinetic equation. We discuss obstacles that limit the theory's validity and suggest how the theory might then be modified. We also compare the experimental evidence with the theory's predictions in a range of applications. Finally, and most importantly, we suggest open challenges and encourage the reader to apply and explore wave turbulence with confidence. The narrative is terse but, we hope, delivered at a speed more akin to the crisp pace of a Hemingway story than the wordjumblingtumbling rate of a Joycean novel. © 2011 by Annual Reviews. All rights reserved.
Gruessner A.C.,University of Arizona
Clinical transplants | Year: 2012
During the last decade, the number of pancreas transplants in the United States (U.S.) has declined by almost 20%, while the number of pancreas transplants performed outside of the U.S. increased. The decline in U.S. numbers is mostly due to the decline in primary pancreas after kidney transplants (PAK). The number of transplants in this category dropped by 50%. The number of simultaneous pancreas/kidney transplants (SPK) only declined slightly. In most cases, pancreas transplants worldwide were performed with a simultaneous kidney transplant (over 90%), which now shows excellent results. In the time period between 2007 and 2011, compared to an earlier era (2002-2006), for transplants in the United States, patient survival at 3 years increased to 93.2%, pancreas graft function to 80%, and kidney function to 87.8%. A significant change could be found in PAK. Three year patient survival increased to 93.6%, and pancreas graft function to 70.5%. With the decline in the number of transplants, a change in donor factors was observed. Especially in solitary transplants, the donors were often younger trauma victims and the pancreas preservation time decreased. Overall, the number of younger recipients decreased.
Hill J.M.,University of Arizona
Applied Optics | Year: 2010
The Large Binocular Telescope (LBT) Observatory is a collaboration among institutions in Arizona, Germany, Italy, Indiana, Minnesota, Ohio, and Virginia. The telescope on Mount Graham in Southeastern Arizona uses two 8:4m diameter primary mirrors mounted side by side. A unique feature of the LBT is that the light from the two Gregorian telescope sides can be combined to produce phasedarray imaging of an extended field. This cophased imaging along with adaptive optics gives the telescope the diffraction-limited resolution of a 22:65m aperture and a collecting area equivalent to an 11:8m circular aperture. This paper describes the design, construction, and commissioning of this unique telescope. We report some sample astronomical results with the prime focus cameras. We comment on some of the technical challenges and solutions. The telescope uses two F/15 adaptive secondaries to correct atmospheric turbulence. The first of these adaptive mirrors has completed final system testing in Firenze, Italy, and is planned to be at the telescope by Spring 2010. © 2010 Optical Society of America.
Howard-Varona C.,University of Arizona
ISME Journal | Year: 2016
Bacteria impact humans, industry and nature, but do so under viral constraints. Problematically, knowledge of viral infection efficiencies and outcomes derives from few model systems that over-represent efficient lytic infections and under-represent virus–host natural diversity. Here we sought to understand infection efficiency regulation in an emerging environmental Bacteroidetes–virus model system with markedly different outcomes on two genetically and physiologically nearly identical host strains. For this, we quantified bacterial virus (phage) and host DNA, transcripts and phage particles throughout both infections. While phage transcriptomes were similar, transcriptional differences between hosts suggested host-derived regulation of infection efficiency. Specifically, the alternative host overexpressed DNA degradation genes and underexpressed translation genes, which seemingly targeted phage DNA particle production, as experiments revealed they were both significantly delayed (by >30 min) and reduced (by >50%) in the inefficient infection. This suggests phage failure to repress early alternative host expression and stress response allowed the host to respond against infection by delaying phage DNA replication and protein translation. Given that this phage type is ubiquitous and abundant in the global oceans and that variable viral infection efficiencies are central to dynamic ecosystems, these data provide a critically needed foundation for understanding and modeling viral infections in nature.The ISME Journal advance online publication, 17 May 2016; doi:10.1038/ismej.2016.81. © 2016 International Society for Microbial Ecology
Kunyansky L.,University of Arizona
Inverse Problems | Year: 2012
Magneto-acousto-electric tomography (MAET), also known as the Lorentz force or Hall effect tomography, is a novel hybrid modality designed to be a high-resolution alternative to the unstable electrical impedance tomography. In this paper, we analyze the existing mathematical models of this method, and propose a general procedure for solving the inverse problem associated with the MAET. It consists in applying to the data one of the algorithms of thermo-acoustic tomography, followed by solving the Neumann problem for the Laplace equation and the Poisson equation. For the particular case when the region of interest is a cube, we present an explicit series solution resulting in a fast reconstruction algorithm. As we show, both analytically and numerically, the MAET is a stable technique yielding high-resolution images even in the presence of significant noise in the data. © 2012 IOP Publishing Ltd.
Laughlin D.C.,University of Waikato |
Messier J.,University of Arizona
Trends in Ecology and Evolution | Year: 2015
Phenotypic traits influence species distributions, but ecology lacks established links between multidimensional phenotypes and fitness for predicting species responses to environmental change. The common focus on single traits rather than multiple trait combinations limits our understanding of their adaptive value, and intraspecific trait covariation has been neglected in ecology despite its importance in evolutionary theory and its likely impact on species distributions. Here, we extend the adaptive landscape framework to ecological sorting of multidimensional phenotypes across environments and discuss how two analytical approaches can be used to quantify fitness as a function of the interaction between the phenotype and the environment. We encourage ecologists to consider how phenotypic integration will constrain species responses to environmental change. © 2015 Elsevier Ltd.
Hay M.,University of Arizona
Clinical Science | Year: 2016
Hypertension is a major contributor to worldwide morbidity and mortality rates related to cardiovascular disease. There are important sex differences in the onset and rate of hypertension in humans. Compared with age-matched men, premenopausal women are less likely to develop hypertension. However, after age 60, the incidence of hypertension increases in women and even surpasses that seen in older men. It is thought that changes in levels of circulating ovarian hormones as women age may be involved in the increase in hypertension in older women. One of the key mechanisms involved in the development of hypertension in both men and women is an increase in sympathetic nerve activity (SNA). Brain regions important for the regulation of SNA, such as the subfornical organ, the paraventricular nucleus and the rostral ventral lateral medulla, also express specific subtypes of oestrogen receptors. Each of these brain regions has also been implicated in mechanisms underlying risk factors for hypertension such as obesity, stress and inflammation. The present review brings together evidence that links actions of oestrogen at these receptors to modulate some of the common brain mechanisms involved in the ability of hypertensive risk factors to increase SNA and blood pressure. Understanding the mechanisms by which oestrogen acts at key sites in the brain for the regulation of SNA is important for the development of novel, sex-specific therapies for treating hypertension. © 2016 Authors.
Duckworth R.A.,University of Arizona |
Sockman K.W.,University of North Carolina at Chapel Hill
Functional Ecology | Year: 2012
Behaviour is often assumed to be the most flexible of traits, yet recent studies show a high repeatability of behaviour within individuals even across different functional contexts. Such consistent expression of behaviour may evolve either when selection favours its integration with less flexible components of the phenotype or when pleiotropic effects produce correlations between behaviours that have different optimal timing of expression. Examining the physiological mechanisms underlying correlated expression of behaviours provides powerful insight into the evolution of personalities by establishing the extent to which pleiotropic effects might limit the independent evolution of distinct behaviours. 2.Here, we investigated proximate mechanisms behind aggressive and non-aggressive personality types in western bluebirds, Sialia mexicana, to determine whether consistency in the expression of aggression is because of shared effects of plasma-circulating androgens on aggression and mating behaviour. 3.We found that androgen concentration was unrelated to variation in both intra- and interspecific aggression even though it was closely linked to variation in male mating behaviour. These results suggest that pleiotropic effects of circulating androgens are unlikely to cause consistent differences among individuals in aggression. 4.These findings suggest that decoupling of the activational effects of hormones on behaviour is an important step in the evolution of personality traits. © 2012 The Authors. Functional Ecology © 2012 British Ecological Society.
Hastings K.T.,University of Arizona |
Cresswell P.,Howard Hughes Medical Institute
Antioxidants and Redox Signaling | Year: 2011
Gamma-interferon-inducible lysosomal thiol reductase (GILT) is constitutively expressed in most antigen presenting cells and is interferon γ inducible in other cell types via signal transducer and activator of transcription 1. Normally, N-and C-terminal propeptides are cleaved in the early endosome, and the mature protein resides in late endosomes and lysosomes. Correspondingly, GILT has maximal reductase activity at an acidic pH. Monocyte differentiation via Toll-like receptor 4 triggers secretion of a disulfide-linked dimer of the enzymatically active precursor, which may contribute to inflammation. GILT facilitates major histocompatibility complex (MHC) class II-restricted processing through reduction of protein disulfide bonds in the endocytic pathway and is hypothesized to expose buried epitopes for MHC class II binding. GILT can also facilitate the transfer of disulfide-containing antigens into the cytosol, enhancing their cross-presentation by MHC class I. A variety of antigens are strongly influenced by GILT-mediated reduction, including hen egg lysozyme, melanocyte differentiation antigens, and viral envelope glycoproteins. In addition, GILT is conserved among lower eukaryotes and likely has additional functions. For example, GILT expression increases the stability of superoxide dismutase 2 and decreases reactive oxygen species, which correlates with decreased cellular proliferation. It is also a critical host factor for infection with Listeria monocytogenes. © 2011 Mary Ann Liebert, Inc.
Tipton C.M.,University of Arizona
Advances in Physiology Education | Year: 2015
In 2007, the American College of Sports Medicine, with endorsement from the American Medical Association and the Office of the Surgeon General, launched a global initiative to mobilize physicians, healthcare professionals and providers, and educators to promote exercise in their practice or activities to prevent, reduce, manage, or treat diseases that impact health and the quality of life in humans. Emerging from this initiative, termed Exercise Is Medicine, has been an extensively documented position stand by the American College of Sports Medicine that recommended healthy adults perform 150 min of moderate dynamic exercise per week. The purpose of this article is to demonstrate the foundation for this global initiative and its exercise prescription for health and disease prevention has roots that began in antiquity more than two millennia ago. Individuals and concepts to remember are that Susruta of India was the first "recorded" physician to prescribe moderate daily exercise, Hippocrates of Greece was the first "recorded" physician to provide a written exercise prescription for a patient suffering from consumption, and the global influence of Galen from Rome combined with his recommendation on the use of exercise for patients in the management of disease prevailed until the 16th century. Historically intertwined wiblth these concepts was exercise being advocated by select physicians to minimize the health proems associated with obesity, diabetes, and inactivity. © 2014 The American Physiological Society.
Shekhawat S.S.,University of Arizona
Current opinion in chemical biology | Year: 2011
It has been estimated that 650,000 protein-protein interactions exist in the human interactome (Stumpf et al., 2008), a subset of all possible macromolecular partnerships that dictate life. Thus there is a continued need for the development of sensitive and user-friendly methods for cataloguing biomacromolecules in complex environments and for detecting their interactions, modifications, and cellular location. Such methods also allow for establishing differences in the interactome between a normal and diseased cellular state and for quantifying the outcome of therapeutic intervention. A promising approach for deconvoluting the role of macromolecular partnerships is split-protein reassembly, also called protein fragment complementation. This approach relies on the appropriate fragmentation of protein reporters, such as the green fluorescent protein or firefly luciferase, which when attached to possible interacting partners can reassemble and regain function, thereby confirming the partnership. Split-protein methods have been effectively utilized for detecting protein-protein interactions in cell-free systems, Escherichia coli, yeast, mammalian cells, plants, and live animals. Herein, we present recent advances in engineering split-protein systems that allow for the rapid detection of ternary protein complexes, small molecule inhibitors, as well as a variety of macromolecules including nucleic acids, poly(ADP) ribose, and iron sulfur clusters. We also present advances that combine split-protein systems with chemical inducers of dimerization strategies that allow for regulating the activity of orthogonal split-proteases as well as aid in identifying enzyme inhibitors. Finally, we discuss autoinhibition strategies leading to turn-on sensors as well as future directions in split-protein methodology including possible therapeutic approaches. Copyright © 2011 Elsevier Ltd. All rights reserved.
Kundu T.,University of Arizona
Ultrasonics | Year: 2014
In this article different techniques for localizing acoustic sources are described and the advantages/disadvantages of these techniques are discussed. Some source localization techniques are restricted to isotropic structures while other methods can be applied to anisotropic structures as well. Some techniques require precise knowledge of the direction dependent velocity profiles in the anisotropic body while other techniques do not require that knowledge. Some methods require accurate values of the time of arrival of the acoustic waves at the receivers while other techniques can function without that information. Published papers introducing various techniques emphasize the advantages of the introduced techniques while ignoring and often not mentioning the limitations and weaknesses of the new techniques. What is lacking in the literature is a comprehensive review and comparison of the available techniques; this article attempts to do that. After reviewing various techniques the paper concludes which source localization technique should be most effective for what type of structure and what the current research needs are. © 2013 Elsevier B.V. All rights reserved.
Neuman S.P.,University of Arizona
Hydrological Processes | Year: 2010
Many earth and environmental variables appear to be self-affine (monofractal) or multifractal with spatial (or temporal) increments having exceedance probability tails that decay as powers of -α where 1 < α ≤ 2. The literature considers selfaffine and multifractal modes of scaling to be fundamentally different, the first arising from additive and the second from multiplicative random fields or processes. We demonstrate theoretically that data having finite support, sampled across a finite domain from one or several realizations of an additive Gaussian field constituting fractional Brownian motion (fBm) characterized by α = 2, give rise to positive square (or absolute) increments which behave as if the field was multifractal when in fact it is monofractal. Sampling such data from additive fractional Lévy motions (fLm) with 1 < α < 2 causes them to exhibit spurious multifractality. Deviations from apparent multifractal behaviour at small and large lags are due to nonzero data support and finite domain size, unrelated to noise or undersampling (the causes cited for such deviations in the literature). Our analysis is based on a formal decomposition of anisotropic fLm (fBm when α = 2) into a continuous hierarchy of statistically independent and homogeneous random fields, or modes, which captures the above behaviour in terms of only E + 3 parameters where E is Euclidean dimension. Although the decomposition is consistent with a hydrologic rationale proposed by Neuman (2003), its mathematical validity is independent of such a rationale. Our results suggest that it may be worth checking how closely would variables considered in the literature to be multifractal (e.g. experimental and simulated turbulent velocities, some simulated porous flow velocities, landscape elevations, rain intensities, river network area and width functions, river flow series, soil water storage and physical properties) fit the simpler monofractal model considered in this paper (such an effort would require paying close attention to the support and sampling window scales of the data). Parsimony would suggest associating variables found to fit both models equally well with the latter. © 2010 John Wiley & Sons, Ltd.
Secomb T.W.,University of Arizona
Medical Engineering and Physics | Year: 2011
Blood is a concentrated suspension of red blood cells (RBCs). Motion and deformation of RBCs can be analyzed based on knowledge of their mechanical characteristics. Axisymmetric models for single-file motion of RBCs in capillaries yield predictions of apparent viscosity in good agreement with experimental results for diameters up to about 8 μm. Two-dimensional simulations, in which each RBC is represented as a set of interconnected viscoelastic elements, predict that off-centre RBCs in an 8-μm channel take asymmetric shapes and drift toward the centre-line. Predicted trajectories agree with observations in microvessels of the rat mesentery. An isolated RBC initially positioned near the wall of a 20-μm channel is deformed into an asymmetric shape, migrates away from the wall, and then enters a complex tumbling motion with continuous shape change. Realistic simulation of multiple interacting RBCs in microvessels remains as a major challenge. © 2010 IPEM.
Briehl M.M.,University of Arizona
Redox Biology | Year: 2015
In the absence of oxygen human life is measured in minutes. In the presence of oxygen, normal metabolism generates reactive species (ROS) that have the potential to cause cell injury contributing to human aging and disease. Between these extremes, organisms have developed means for sensing oxygen and ROS and regulating their cellular processes in response. Redox signaling contributes to the control of cell proliferation and death. Aberrant redox signaling underlies many human diseases. The attributes acquired by altered redox homeostasis in cancer cells illustrate this particularly well. This teaching review and the accompanying illustrations provide an introduction to redox biology and signaling aimed at instructors of graduate and medical students. © 2015 The Authors.
Ozel F.,University of Arizona
Reports on progress in physics. Physical Society (Great Britain) | Year: 2013
Neutron stars are associated with diverse physical phenomena that take place in conditions characterized by ultrahigh densities as well as intense gravitational, magnetic and radiation fields. Understanding the properties and interactions of matter in these regimes remains one of the challenges in compact object astrophysics. Photons emitted from the surfaces of neutron stars provide direct probes of their structure, composition and magnetic fields. In this review, I discuss in detail the physics that governs the properties of emission from the surfaces of neutron stars and their various observational manifestations. I present the constraints on neutron star radii, core and crust composition, and magnetic field strength and topology obtained from studies of their broadband spectra, evolution of thermal luminosity, and the profiles of pulsations that originate on their surfaces.
Hastings K.T.,University of Arizona
Frontiers in Immunology | Year: 2013
The MHC class II-restricted antigen processing pathway generates peptide:MHC complexes in the endocytic pathway for the activation of CD4+ T cells. Gamma-interferon-inducible lysosomal thiol reductase (GILT) reduces protein disulfide bonds in the endocytic compartment, thereby exposing buried epitopes for MHC class II binding and presentation. T cell hybridoma responses and elution of MHC class II bound peptides have identified GILT-dependent epitopes, GILT-independent epitopes, and epitopes that are more efficiently presented in the absence of GILT termed GILT-prevented epitopes. GILT-mediated alteration in the MHC class II-restricted peptidome modulates T cell development in the thymus and peripheral tolerance and influences the pathogenesis of autoimmunity. Recent studies suggest an emerging role for GILT in the response to pathogens and cancer survival. © 2013 Hastings.
Dow C.A.,University of Arizona
Journal of the American Heart Association | Year: 2013
Weight loss is associated with improvements in cardiometabolic risk factors, including serum glucose, insulin, C-reactive protein, and blood lipids. Few studies have evaluated the long-term (>18 months) effect of weight loss on these risk factors or sought to identify factors associated with sustained improvements in these measures. In 417 overweight/obese women (mean [SD] age, 44  years) participating in a weight loss trial, we sought to identify predictors of weight loss-associated cardiometabolic risk factors after 12 and 24 months of intervention. Total cholesterol (TC), low-density lipoprotein (LDL)-cholesterol (LDL-C), high-density lipoprotein (HDL)-cholesterol, non-HDL-cholesterol, triglycerides (TG), insulin, glucose, C-reactive protein (CRP), and cardiopulmonary fitness were measured at baseline and at 12 and 24 months. After 24 months, significant reductions in body weight, waist circumference, CRP, TC, HDL-cholesterol, and non-HDL-cholesterol were observed (P<0.01). After 24 months, mean TC and non-HDL-cholesterol were reduced regardless of the amount of weight lost, whereas reductions in LDL-cholesterol, CRP, insulin, and TG were observed only in those who lost ≥10% body weight. Step-test performance improved only in those who lost ≥10% body weight after 24 months. Change in weight demonstrated a positive predictive value for change in cholesterol, insulin, glucose, and triglycerides. Baseline level of the biomarker showed the greatest predictive value for follow-up measures for insulin, cholesterol, glucose, and triglycerides. Our data extend the results from short-term weight loss trials and suggest that the magnitude of weight loss and baseline values for risk factors are associated with improvements in cardiometabolic risk factors even after 24 months. http://www.clinicaltrials.gov/. Unique identifier: NCT00640900.
Bootzin R.R.,University of Arizona |
Epstein D.R.,Phoenix Veterans Affairs Health Care System
Annual Review of Clinical Psychology | Year: 2011
Sleep disturbance is intricately entwined with our sense of well-being, health, emotion regulation, performance and productivity, memory and cognitive functioning, and social interaction. A longitudinal perspective underscores the conclusion that persistent sleep disturbance, insomnia, at any time during the life span from infancy to old age has a lasting impact. We examine how insomnia develops, the evidence for competing explanations for understanding insomnia, and the evidence about psychological and behavioral treatments that are used to reduce insomnia and change daytime consequences. There are new directions to expand access to treatment for those who have insomnia, and thus a critical analysis of pathways for dissemination is becoming increasingly important. Copyright © 2011 by Annual Reviews. All rights reserved.
Goff S.A.,University of Arizona
New Phytologist | Year: 2011
Summary 923 I. Introduction 924 II. Early studies of heterosis 924 III. Heterosis in diverse species 926 IV. Gene expression studies 926 V. Protein metabolism 927 VI. Allele-specific gene expression 928 VII. Quality control 929 VIII. A synthesis model 930 IX. Putting the model to work 932 Acknowledgements 933 References 933 +Summary: Hybrids between genetically diverse varieties display enhanced growth, and increased total biomass, stress resistance and grain yield. Gene expression and metabolic studies in maize, rice and other species suggest that protein metabolism plays a role in the growth differences between hybrids and inbreds. Single trait heterosis can be explained by the existing theories of dominance, overdominance and epistasis. General multigenic heterosis is observed in a wide variety of different species and is likely to share a common underlying biological mechanism. This review presents a model to explain differences in growth and yield caused by general multigenic heterosis. The model describes multigenic heterosis in terms of energy-use efficiency and faster cell cycle progression where hybrids have more efficient growth than inbreds because of differences in protein metabolism. The proposed model is consistent with the observed variation of gene expression in different pairs of inbred lines and hybrid offspring as well as growth differences in polyploids and aneuploids. It also suggests an approach to enhance yield gains in both hybrid and inbred crops via the creation of an appropriate computational analysis pipeline coupled to an efficient molecular breeding program. © 2010 The Author. New Phytologist © 2010 New Phytologist Trust.
Martinez F.D.,University of Arizona
Annals of the American Thoracic Society | Year: 2014
The development of new technologies to isolate and identify microbial genomes has markedly increased our understanding of the role of microbiomes in health and disease. The idea, first proposed as part of the hygiene hypothesis, that environmental microbes influence the developmental trajectories of the immune system in early life, has now been considerably extended and refined. The abundantmicrobiota present inmucosal surfaces, especially the gut, is actively selected by the host through complex receptor systems that respond differentially depending on the molecular patterns presented to mucosal cells. Germ-free mice are more likely to develop allergic airway inflammation and show alterations in normal motor control and anxiety. These effects can be reversed by neonatal microbial recolonization but remain unchanged if recolonization occurs in adults. What emerges from these recent studies is the discovery of a complex, major early environmental determinant of lifetime human phenotypes. To change the natural course of asthma, obesity, and other chronic inflammatory conditions, active manipulation of the extensive bacterial, phage, and fungal metagenomes present in mucosal surfaces may be required, specifically during the developing years. Domesticating the human microbiome and adapting it to our health needs may be a challenge akin to, but far more complex than, the one faced by humanity when a few dozen species of plants and animals were domesticated during the transition between hunter-gatherer and sedentary societies after the end of the Pleistocene era. Copyright © 2014 by the American Thoracic Society.
Erickson R.P.,University of Arizona
Journal of Applied Genetics | Year: 2013
There has been a recent explosion in research on Niemann-Pick type C disease. Much of the work has used mouse models or cells in culture to elucidate the pathophysiological mechanisms resulting in the phenotype of the disease. This work has generated several contrasting views on the mechanism, which are labeled 'controversies' here. In this review, two of these controversies are explored. The first concerns which stored materials are causative in the disease: cholesterol, gangliosides and sphingolipids, or something else? The second concerns which cells in the body require Npc1 in order to function properly: somatic cells, neurons only, or neurons and glia? For the first controversy, a clear answer has emerged. More research will be needed in order to definitively solve the second controversy. © 2013 Institute of Plant Genetics, Polish Academy of Sciences, Poznan.
Eisner J.A.,University of Arizona
Astrophysical Journal | Year: 2012
We present imaging observations at the 1.3mm wavelength of ClassI protostars in the Taurus star-forming region, obtained with the CARMA interferometer. Of an initial sample of 10 objects, we detected and imaged millimeter wavelength emission from 9. One of the nine is resolved into two sources and detailed analysis of this binary protostellar system is deferred to a future paper. For the remaining eight objects, we use the CARMA data to determine the basic morphology of the millimeter emission. Combining the millimeter data with 0.9 μm images of scattered light, Spitzer Infrared Spectrograph spectra, and broadband spectral energy distributions (all from the literature), we attempt to determine the structure of the circumstellar material. We consider models including both circumstellar disks and envelopes, and constrain the masses (and other structural parameters) of each of these components. We show that the disk masses in our sample span a range from ≲ 0.01 to ≳ 0.1 M. The disk masses for our sample are significantly higher than for samples of more evolved ClassII objects. Thus, ClassI disk masses probably provide a more accurate estimate of the initial mass budget for star and planet formation. However, the disk masses determined here are lower than required by theories of giant planet formation. The masses also appear too low for gravitational instability, which could lead to high mass accretion rates. Even in these ClassI disks, substantial particle growth may have hidden much of the disk mass in hard-to-see larger bodies. © 2012 The American Astronomical Society. All rights reserved.
Cao T.T.,University of Arizona
Behavioral Ecology and Sociobiology | Year: 2013
Many organisms live in crowded groups where social density affects behavior and fitness. Social insects inhabit nests that contain many individuals where physical interactions facilitate information flow and organize collective behaviors such as foraging, colony defense, and nest emigration. Changes in nest space and intranidal crowding can alter social interactions and affect worker behavior. Here, I examined the effects of social density on foraging, scouting, and polydomy behavior in ant colonies-using the species Temnothorax rugatulus. First, I analyzed field colonies and determined that nest area scaled isometrically with colony mass-this indicates that nest area changes proportionally with colony size and suggests that ants actively control intranidal density. Second, laboratory experiments showed that colonies maintained under crowded conditions had greater foraging and scouting activities compared to the same colonies maintained at a lower density. Moreover, crowded colonies were significantly more likely to become polydomous. Polydomous colonies divided evenly based on mass between two nests but distributed fewer, heavier workers and brood to the new nests. Polydomous colonies also showed different foraging and scouting rates compared to the same colonies under monodomous conditions. Combined, the results indicate that social density is an important colony phenotype that affects individual and collective behavior in ants. I discuss the function of social density in affecting communication and the organization of labor in social insects and hypothesize that the collective management of social density is a group level adaptation in social insects. © 2013 Springer-Verlag Berlin Heidelberg.
Katz B.,Institute for Advanced Study |
Dong S.,Institute for Advanced Study |
Malhotra R.,University of Arizona
Physical Review Letters | Year: 2011
The very long-term evolution of the hierarchical restricted three-body problem is calculated analytically for high inclinations. The Kozai-Lidov Cycles (KLCs) slowly evolve due to the octupole term in the perturber's potential and exhibit striking features, including extremely high eccentricities and the generation of retrograde orbits with respect to the perturber. These features were found in recent numerical experiments of the nonrestricted three-body problem and were attributed inaccurately to the comparable and low masses of the two orbiting companions. Our calculation is done by averaging for the first time the double averaged secular equations of motion over the KLCs and finding a new constant of the motion. These very long-term effects are likely to be important in various astrophysical systems thought to involve KLCs, such as hot Jupiters, irregular moons of planets, and many others. © 2011 American Physical Society.
Rauscher E.,University of Arizona |
Menou K.,Columbia University
Astrophysical Journal | Year: 2012
In contrast to the Earth, where frictional heating is typically negligible, we show that drag mechanisms could act as an important heat source in the strongly forced atmospheres of some exoplanets, with the potential to alter the circulation. We modify the standard formalism of the atmospheric energy cycle to explicitly track the loss of kinetic energy and the associated frictional (re)heating, for application to exoplanets such as the asymmetrically heated "hot Jupiters" and gas giants on highly eccentric orbits. We establish that an understanding of the dominant drag mechanisms and their dependence on local atmospheric conditions is critical for accurate modeling, not just in their ability to limit wind speeds, but also because they could possibly change the energetics of the circulation enough to alter the nature of the flow. We discuss possible sources of drag and estimate the strength necessary to significantly influence the atmospheric energetics. As we show, the frictional heating depends on the magnitude of kinetic energy dissipation as well as its spatial variation, so that the more localized a drag mechanism is, the weaker it can be and still affect the circulation. We also use the derived formalism to estimate the rate of numerical loss of kinetic energy in a few previously published hot Jupiter models with and without magnetic drag and find it to be surprisingly large, at 5%-10% of the incident stellar irradiation. © 2012. The American Astronomical Society. All rights reserved.
Wu H.J.,University of Arizona
Gut microbes | Year: 2012
Keeping a delicate balance in the immune system by eliminating invading pathogens, while still maintaining self-tolerance to avoid autoimmunity, is critical for the body's health. The gut microbiota that resides in the gastrointestinal tract provides essential health benefits to its host, particularly by regulating immune homeostasis. Moreover, it has recently become obvious that alterations of these gut microbial communities can cause immune dysregulation, leading to autoimmune disorders. Here we review the advances in our understanding of how the gut microbiota regulates innate and adaptive immune homeostasis, which in turn can affect the development of not only intestinal but also systemic autoimmune diseases. Exploring the interaction of gut microbes and the host immune system will not only allow us to understand the pathogenesis of autoimmune diseases but will also provide us new foundations for the design of novel immuno- or microbe-based therapies.
Donnerstein E.,University of Arizona
Pediatric Clinics of North America | Year: 2012
There is substantial literature on the impact of the mass media on children's and adolescents' health and development. The question of what role new technology plays in the media's influence is now a subject of both review and discussion, particularly regarding health risks and intervention. This article takes a brief look at online usage and the theoretical mechanisms that might make Internet access more problematic in terms of risks, compared with more traditional media such as television and film. One of these risks, known today as cyberbullying or Internet harassment, is scrutinized in detail. © 2012 Elsevier Inc.
Freeman W.,George Washington University |
Toussaint D.,University of Arizona
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013
We calculate the intrinsic strangeness of the nucleon, N|s̄s|NŸ ©- 0|s̄s|0Ÿ©, using the MILC library of improved staggered gauge configurations using the Asqtad and HISQ actions. Additionally, we present a preliminary calculation of the intrinsic charm of the nucleon using the HISQ action with dynamical charm. The calculation is done with a method which incorporates features of both commonly used methods, the direct evaluation of the three-point function and the application of the Feynman-Hellman theorem. We present an improvement on this method that further reduces the statistical error, and check the result from this hybrid method against the other two methods and find that they are consistent. The values for N|s̄s|NŸ © and N|c̄c|NŸ© found here, together with perturbative results for heavy quarks, show that dark matter scattering through Higgs-like exchange receives roughly equal contributions from all heavy quark flavors. © 2013 American Physical Society.
Giacalone J.,University of Arizona
Astrophysical Journal | Year: 2012
We analyze observations of energetic charged particles associated with many strong interplanetary shocks seen by Advanced Composition Explorer. We focus primarily on 47-187 keV suprathermal protons and restrict our analysis to strong interplanetary shocks (Alfvén Mach number >3 and the shock density compression >2.5). Eighteen shocks meeting this criterion from 1998 to 2003 were analyzed. All 18 had enhancements of the 47-65 keV proton intensity above the intensity seen one day before the shock. In 17 events, the particle intensity either rose to a quasi-plateau or peaked within 10 minutes of the shock. Most had intensities at the shock exceeding 100 times more than that seen the day before the shock arrived. The time-intensity profiles of the energetic proton events in many cases reveal a rise before the shock passage reaching a quasi-plateau or local peak at the shock, followed by a gradual decline. This suggests that the shock itself is the source of energetic particles. Energy spectra behind the shock were fit to an assumed power law over the interval from 46 to 187 keV, and the resulting spectral index was compared to the plasma density jump across each shock. Most events agree with the prediction of diffusive shock acceleration theory to within the observational uncertainties. We also analyzed a few selected events to determine the particle spatial diffusion coefficients and acceleration timescales. We find that the time to accelerate protons to 50 keV is of the order of an hour. © 2012. The American Astronomical Society. All rights reserved..
Wilcox J.,University of Arizona
Journal of Psychoactive Drugs | Year: 2012
This is a retrospective examination of former users of alpha-methyltryptamine (AMT). A scale of questions was given to subjects who were familiar with the effects of AMT and the outcome was analyzed. Most subjects agreed that AMT had strong hallucinogenic qualities. The most common unwanted effects included anxiety, nausea and moderately severe dysphoria. Several subjects reported significant depression associated with use of AMT. Use of alpha-methyltryptamine could be dangerous in individuals prone to depression. © Taylor & Francis Group, LLC.
Diamond-Stanic A.M.,University of California at San Diego |
Rieke G.H.,University of Arizona
Astrophysical Journal | Year: 2012
We present estimates of black hole accretion rates (BHARs) and nuclear, extended, and total star formation rates for a complete sample of Seyfert galaxies. Using data from the Spitzer Space Telescope, we measure the active galactic nucleus (AGN) luminosity using the [O IV] λ25.89 μm emission line and the star-forming luminosity using the 11.3 μm aromatic feature and extended 24 μm continuum emission. We find that black hole growth is strongly correlated with nuclear (r < 1kpc) star formation, but only weakly correlated with extended (r > 1kpc) star formation in the host galaxy. In particular, the nuclear star formation rate (SFR) traced by the 11.3 μm aromatic feature follows a relationship with the BHAR of the form SFR ∞ M· 0.8 BH, with an observed scatter of 0.5 dex. This SFR-BHAR relationship persists when additional star formation in physically matched r = 1kpc apertures is included, taking the form SFR ∞ M · 0.8 BH. However, the relationship becomes almost indiscernible when total SFRs are considered. This suggests a physical connection between the gas on sub-kiloparsec and sub-parsec scales in local Seyfert galaxies that is not related to external processes in the host galaxy. It also suggests that the observed scaling between star formation and black hole growth for samples of AGNs will depend on whether the star formation is dominated by a nuclear or an extended component. We estimate the integrated black hole and bulge growth that occurs in these galaxies and find that an AGN duty cycle of 5%-10% would maintain the ratio between black hole and bulge masses seen in the local universe. © 2012. The American Astronomical Society. All rights reserved.
Kiminki D.C.,University of Wyoming |
Kiminki D.C.,University of Arizona |
Kobulnicky H.A.,University of Wyoming
Astrophysical Journal | Year: 2012
This work provides a statistical analysis of the massive star binary characteristics in the Cygnus OB2 association using radial velocity information of 114 B3-O5 primary stars and orbital properties for the 24 known binaries. We compare these data to a series of Monte Carlo simulations to infer the intrinsic binary fraction and distributions of mass ratios, periods, and eccentricities. We model the distribution of mass ratio, log-period, and eccentricity as power laws and find best-fitting indices of α = 0.1 ± 0.5, β = 0.2 ± 0.4, and γ = -0.6 ± 0.3, respectively. These distributions indicate a preference for massive companions, short periods, and low eccentricities. Our analysis indicates that the binary fraction of the cluster is 44% ± 8% if all binary systems are (artificially) assumed to have P < 1000 days; if the power-law period distribution is extrapolated to 10 4 years, then a plausible upper limit for bound systems, the binary fraction is 90% ± 10%. Of these binary (or higher order) systems, 45% will have companions close enough to interact during pre- or post-main-sequence evolution (semi-major axis ≲4.7 AU). The period distribution for P < 26 days is not well reproduced by any single power law owing to an excess of systems with periods around 3-5 days (0.08-0.31 AU) and a relative shortage of systems with periods around 7-14 days (0.14-0.62 AU). We explore the idea that these longer-period systems evolved to produce the observed excess of short-period systems. The best-fitting binary parameters imply that secondaries generate, on average, 16% of the V-band light in young massive populations. This means that photometrically based distance measurements for young massive clusters and associations will be systematically low by 8% (0.16 mag in the distance modulus) if the luminous contributions of unresolved secondaries are not taken into account. © 2012. The American Astronomical Society. All rights reserved..
Rauscher E.,University of Arizona |
Menou K.,Columbia University
Astrophysical Journal | Year: 2012
We present a new version of our code for modeling the atmospheric circulation on gaseous exoplanets, now employing a "double-gray" radiative transfer scheme, which self-consistently solves for fluxes and heating throughout the atmosphere, including the emerging (observable) infrared flux. We separate the radiation into infrared and optical components, each with its own absorption coefficient, and solve standard two-stream radiative transfer equations. We use a constant optical absorption coefficient, while the infrared coefficient can scale as a power law with pressure; however, for simplicity, the results shown in this paper use a constant infrared coefficient. Here we describe our new code in detail and demonstrate its utility by presenting a generic hot Jupiter model. We discuss issues related to modeling the deepest pressures of the atmosphere and describe our use of the diffusion approximation for radiative fluxes at high optical depths. In addition, we present new models using a simple form for magnetic drag on the atmosphere. We calculate emitted thermal phase curves and find that our drag-free model has the brightest region of the atmosphere offset by ∼12° from the substellar point and a minimum flux that is 17% of the maximum, while the model with the strongest magnetic drag has an offset of only ∼2° and a ratio of 13%. Finally, we calculate rates of numerical loss of kinetic energy at ∼15% for every model except for our strong-drag model, where there is no measurable loss; we speculate that this is due to the much decreased wind speeds in that model. © © 2012. The American Astronomical Society. All rights reserved.
Miller-Ricci Kempton E.,University of California at Santa Cruz |
Rauscher E.,University of Arizona
Astrophysical Journal | Year: 2012
Three-dimensional (3D) dynamical models of hot Jupiter atmospheres predict very strong wind speeds. For tidally locked hot Jupiters, winds at high altitude in the planet's atmosphere advect heat from the day side to the cooler night side of the planet. Net wind speeds on the order of 1-10 kms-1 directed towards the night side of the planet are predicted at mbar pressures, which is the approximate pressure level probed by transmission spectroscopy. These winds should result in an observed blueshift of spectral lines in transmission on the order of the wind speed. Indeed, Snellen et al. recently observed a 2 ± 1 kms-1 blueshift of CO transmission features for HD209458b, which has been interpreted as a detection of the day-to-night (substellar to anti-stellar) winds that have been predicted by 3D atmospheric dynamics modeling. Here, we present the results of a coupled 3D atmospheric dynamics and transmission spectrum model, which predicts the Doppler-shifted spectrum of a hot Jupiter during transit resulting from winds in the planet's atmosphere. We explore four different models for the hot Jupiter atmosphere using different prescriptions for atmospheric drag via interaction with planetary magnetic fields. We find that models with no magnetic drag produce net Doppler blueshifts in the transmission spectrum of 2 kms-1 and that lower Doppler shifts of 1 kms-1 are found for the higher drag cases, results consistent with - but not yet strongly constrained by - the Snellen et al. measurement. We additionally explore the possibility of recovering the average terminator wind speed as a function of altitude by measuring Doppler shifts of individual spectral lines and spatially resolving wind speeds across the leading and trailing terminators during ingress and egress. © 2012. The American Astronomical Society. All rights reserved..
Goriely A.,University of Oxford |
Tabor M.,University of Arizona
Physical Review Letters | Year: 2011
The filamentary fungus Phycomyces blakesleeanus undergoes a series of remarkable transitions during aerial growth. During what is known as the stagea IV growth phase, the fungus extends while rotating in a counterclockwise manner when viewed from above (stagea IVa) and then, while continuing to grow, spontaneously reverses to a clockwise rotation (stagea IVb). This phase lasts for 24-48Ah and is sometimes followed by yet another reversal (stageAIVc) before the overall growth ends. Here, we propose a continuum mechanical model of this entire process using nonlinear, anisotropic, elasticity and show how helical anisotropy associated with the cell wall structure can induce spontaneous rotation and, under appropriate circumstances, the observed reversal of rotational handedness. © 2011 American Physical Society.
Arteaga-Vazquez M.A.,University of Arizona
Current opinion in genetics & development | Year: 2010
Paramutation involves trans-interactions between alleles or homologous sequences that establish distinct gene expression states that are heritable for generations. It was first described in maize by Alexander Brink in the 1950s, with his studies of the red1 (r1) locus. Since that time, paramutation-like phenomena have been reported in other maize genes, other plants, fungi, and animals. Paramutation can occur between endogenous genes, two transgenes or an endogenous gene, and transgene. Recent results indicate that paramutation involves RNA-mediated heritable chromatin changes and a number of genes implicated in RNAi pathways. However, not all aspects of paramutation can be explained by known mechanisms of RNAi-mediated transcriptional silencing. 2010 Elsevier Ltd. All rights reserved.
Rosenbloom S.,University of Arizona
Journal of Transport Geography | Year: 2010
Both the UK and the US have rapidly ageing and increasingly diverse populations very dependent on driving. A comparative study commissioned by the UK Department for Transport found that in both the UK and the US adult children of older drivers, whilst often concerned about their parents' continued driving, were also worried about the burden they would carry when their parents stopped driving, although there were differences by race and ethnicity. This study suggests that a policy window may be opening through which babyboomers can advocate for a range of driver training, roadway and vehicle improvements, expansion and enhancement of traditional public transportation and community transport options, improvements in accessibility and pedestrian infrastructure, and supportive land use and housing policies that would allow older people to drive safely longer, and, find meaningful mobility options when they can no longer drive. Policy responses must recognise and respond appropriately to differences by race and ethnicity. © 2010 Elsevier Ltd.
Premo L.S.,Max Planck Institute for Evolutionary Anthropology |
Kuhn S.L.,University of Arizona
PLoS ONE | Year: 2010
The persistence of early stone tool technologies has puzzled archaeologists for decades. Cognitively based explanations, which presume either lack of ability to innovate or extreme conformism, do not account for the totality of the empirical patterns. Following recent research, this study explores the effects of demographic factors on rates of culture change and diversification. We investigate whether the appearance of stability in early Paleolithic technologies could result from frequent extinctions of local subpopulations within a persistent metapopulation. A spatially explicit agent-based model was constructed to test the influence of local extinction rate on three general cultural patterns that archaeologists might observe in the material record: total diversity, differentiation among spatially defined groups, and the rate of cumulative change. The model shows that diversity, differentiation, and the rate of cumulative cultural change would be strongly affected by local extinction rates, in some cases mimicking the results of conformist cultural transmission. The results have implications for understanding spatial and temporal patterning in ancient material culture. © 2010 Premo, Kuhn.
Fishback P.,University of Arizona
Oxford Review of Economic Policy | Year: 2010
The paper provides a survey of fiscal and monetary policies during the 1930s under the Hoover and Roosevelt administrations and how they influenced the policies during the recent Great Recession. The discussion of the causal impacts of monetary policy focuses on papers written in the last decade and the findings of scholars using dynamic structural general equilibrium modelling. The discussion of fiscal policy shows why economists do not see the New Deal as a Keynesian stimulus, describes the significant shift toward excise taxation during the 1930s, and surveys estimates of the impact of federal spending on local economies. The paper concludes with discussion of the lessons for the present from 1930s monetary and fiscal policy. © The Author 2010. Published by Oxford University Press.
Neugebauer M.,University of Arizona
Astrophysical Journal | Year: 2012
It is proposed that the interplanetary manifestations of X-ray jets observed in solar polar coronal holes during periods of low solar activity are the peaks of the so-called microstreams observed in the fast polar solar wind. These microstreams exhibit velocity fluctuations of ±35kms-1, higher kinetic temperatures, slightly higher proton fluxes, and slightly higher abundances of the low-first-ionization-potential element iron relative to oxygen ions than the average polar wind. Those properties can all be explained if the fast microstreams result from the magnetic reconnection of bright-point loops, which leads to X-ray jets which, in turn, result in solar polar plumes. Because most of the microstream peaks are bounded by discontinuities of solar origin, jets are favored over plumes for the majority of the microstream peaks. © 2012 The American Astronomical Society. All rights reserved.
Stiner M.C.,University of Arizona |
Munro N.D.,University of Connecticut
Journal of Human Evolution | Year: 2011
Franchthi Cave in southern Greece preserves one of the most remarkable records of socioeconomic change of the Late Pleistocene through early Holocene. Located on the southern end of the Argolid Peninsula, the area around the site was greatly affected by climate variation and marine transgression. This study examines the complex interplay of site formation processes (material deposition rates), climate-driven landscape change, and human hunting systems during the Upper Paleolithic through Mesolithic at Franchthi Cave based on the H1B faunal series. Building on earlier work, we establish the full spectrum of the meat diet using taphonomic evidence, and we analyze these data for trends in socioeconomic reorganization. Foraging patterns during the Aurignacian and " Gravettoid" occupations at Franchthi were terrestrial and already rather diversified in comparison to Middle Paleolithic diets in southern Greece. Hunting shifted abruptly to a mixed marine-terrestrial pattern during the Final Paleolithic, and fishing activities intensified though the Mesolithic. The zooarchaeological data indicate two consecutive trends of increasing dietary breadth, the first within an exclusively terrestrial context, and the second as marine habitats came into use through the end of the Mesolithic. The intensity of the human occupations at this site increased in tandem with intensified use of animal and plants. Comparison to the inland site of Klissoura Cave 1 indicates that the trend toward broader diets was regional as well as local. © 2010 Elsevier Ltd.
Melia F.,University of Arizona
Astronomy and Astrophysics | Year: 2014
Context. The emergence of several unexpected large-scale features in the cosmic microwave background (CMB) has pointed to possible new physics driving the origin of density fluctuations in the early Universe and their evolution into the large-scale structure we see today. Aims. In this paper, we focus our attention on the possible absence of angular correlation in the CMB anisotropies at angles larger than ~60, and consider whether this feature may be the signature of fluctuations expected in the Rh = ct Universe. Methods. We calculate the CMB angular correlation function for a fluctuation spectrum expected from growth in a Universe whose dynamics is constrained by the equation-of-state p =-ρ/3, where p and ρ are the total pressure and density, respectively. Results. We find that, though the disparity between the predictions of ΛCDM and the WMAP sky may be due to cosmic variance, it may also be due to an absence of inflation. The classic horizon problem does not exist in the Rh = ct Universe, so a period of exponential growth was not necessary in this cosmology in order to account for the general uniformity of the CMB (save for the aforementioned tiny fluctuations of 1 part in 100 000 in the WMAP relic signal). Conclusions. We show that the Rh = ct Universe without inflation can account for the apparent absence in CMB angular correlation at angles θ â‰ 60 without invoking cosmic variance, providing additional motivation for pursuing this cosmology as a viable description of nature. © 2014 ESO.
Wiens J.J.,University of Arizona
Biology Letters | Year: 2015
The major clades of vertebrates differ dramatically in their current species richness, from 2 to more than 32 000 species each, but the causes of this variation remain poorly understood. For example, a previous study noted that vertebrate clades differ in their diversification rates, but did not explain why they differ. Using a time-calibrated phylogeny and phylogenetic comparative methods, I show that most variation in diversification rates among 12 major vertebrate clades has a simple ecological explanation: predominantly terrestrial clades (i.e. birds, mammals, and lizards and snakes) have higher net diversification rates than predominantly aquatic clades (i.e. amphibians, crocodilians, turtles and all fish clades). These differences in diversification rates are then strongly related to patterns of species richness. Habitat may be more important than other potential explanations for richness patterns in vertebrates (such as climate and metabolic rates) and may also help explain patterns of species richness in many other groups of organisms. © 2015 The Author(s) Published by the Royal Society. All rights reserved.
Ganapol B.D.,University of Arizona
Journal of Quantitative Spectroscopy and Radiative Transfer | Year: 2015
The discrete ordinates method (DOM) of solution to the 1D radiative transfer equation has been an effective method of solution for nearly 70 years. During that time, the method has experienced numerous improvements as numerical and computational techniques have become more powerful and efficient. Here, we again consider the analytical solution to the discrete radiative transfer equation in a homogeneous medium by proposing a new, and consistent, form of solution that improves upon previous forms. Aided by a Wynn-epsilon convergence acceleration, its numerical evaluation can achieve extreme precision as demonstrated by comparison with published benchmarks. Finally, we readily extend the solution to a heterogeneous medium through the star product formulation producing a novel benchmark for closed form Henyey-Greenstein scattering as an example. © 2014 Elsevier Ltd. All rights reserved.
Thompson R.I.,University of Arizona
Monthly Notices of the Royal Astronomical Society: Letters | Year: 2012
Changes in the values of the fundamental constants μ, the proton to electron mass ratio, and α, the fine structure constant due to rolling scalar fields, have been discussed both in the context of cosmology and in newphysics such as supersymmetry models. This Letter examines the changes in these fundamental constants in a particular example of such fields, freezing and thawing slow roll quintessence. Constraints are placed on the product of a cosmological quantity, w, the equation of state parameter, and the square of the coupling constants for μ and α with the field, ζ x (x = μ, α), using the existing observational limits on the values of Δx/x. Various examples of slow-rolling quintessence models are used to further quantify the constraints. Some of the examples appear to be rejected by the existing data which strongly suggest that conformation to the values of the fundamental constants in the early universe is a standard test that should be applied to any cosmological model or suggested new physics. © 2012 The Author Monthly Notices of the Royal Astronomical Society © 2012 RAS.
Melia F.,University of Arizona
Astronomical Journal | Year: 2012
The analysis of Type Ia supernova data over the past decade has been a notable success story in cosmology. These standard candles offer us an unparalleled opportunity to study the cosmological expansion out to a redshift of 1.5. The consensus today appears to be that ΛCDM offers the best explanation for the luminosity-distance relationship seen in these events. However, a significant incompatibility is now emerging between the standard model and other equally important observations, such as those of the cosmic microwave background. ΛCDM does not provide an accurate representation of the cosmological expansion at high redshifts (z ≫ 2). It is therefore essential to re-analyze the Type Ia supernova data in light of the cosmology (the R h = ct universe) that best represents the universe's dynamical evolution at early times. In this paper, we directly compare the distance relationship in ΛCDM with that predicted by R h = ct, and each with the Union2.1 sample, and show that the two theories produce virtually indistinguishable profiles, though the fit with R h = ct has not yet been optimized. This is because the data cannot be determined independently of the assumed cosmology - the supernova luminosities must be evaluated by optimizing four parameters simultaneously with those in the adopted model. This renders the data compliant to the underlying theory, so the model-dependent data reduction should not be ignored in any comparative analysis between competing cosmologies. In this paper, we use R h = ct to fit the data reduced with ΛCDM, and though quite promising, the match is not perfect. An even better fit would result with an optimization of the data using R h = ct from the beginning. © © 2012. The American Astronomical Society. All rights reserved.
Michaliszyn S.F.,University of Arizona
Research in nursing & health | Year: 2010
The purpose of this study was to describe the associations between levels of physical activity measured by accelerometry and changes in fitness, body composition, lipids, and glucose control (i.e., glycosolated hemoglobin [A1C]) in a sample of 16 adolescents with type 1 diabetes participating in a personalized exercise program. More sedentary activity was associated with lower fitness and fat free mass and increased total cholesterol, low-density lipoprotein (LDL-c), and triglycerides (p<.05). Greater amounts of moderate to vigorous activity were associated with higher fitness and fat free mass, and decreased total cholesterol, LDL-c, triglycerides, and A1C (p<.05). Findings support the beneficial effects of increased moderate activity and decreased sedentary behavior to reduce cardiovascular risks and improve glucose control in adolescents with type 1 diabetes. © 2010 Wiley Periodicals, Inc. Res Nurs Health 33:441-449, 2010.
Birky Jr. C.W.,University of Arizona
PLoS ONE | Year: 2013
Phylogenetic trees of DNA sequences of a group of specimens may include clades of two kinds: those produced by stochastic processes (random genetic drift) within a species, and clades that represent different species. The ratio of the mean pairwise sequence difference between a pair of clades (K) to the mean pairwise sequence difference within a clade (θ) can be used to determine whether the clades are samples from different species (K/θ≥4) or the same species (K/θ<4) with probability ≥0.95. Previously I applied this criterion to delimit species of asexual organisms. Here I use data from the literature to show how it can also be applied to delimit sexual species using four groups of sexual organisms as examples: ravens, spotted leopards, sea butterflies, and liverworts. Mitochondrial or chloroplast genes are used because these segregate earlier during speciation than most nuclear genes and hence detect earlier stages of speciation. In several cases the K/θ ratio was greater than 4, confirming the original authors' intuition that the clades were sufficiently different to be assigned to different species. But the K/θ ratio split each of two liverwort species into two evolutionary species, and showed that support for the distinction between the common and Chihuahuan raven species is weak. I also discuss some possible sources of error in using the K/θ ratio; the most significant one would be cases where males migrate between different populations but females do not, making the use of maternally inherited organelle genes problematic. The K/θ ratio must be used with some caution, like all other methods for species delimitation. Nevertheless, it is a simple theory-based quantitative method for using DNA sequences to make rigorous decisions about species delimitation in sexual as well as asexual eukaryotes. © 2013 C. William Birky Jr.
Matsuyama I.,University of Arizona
Icarus | Year: 2013
The unusual shape of the Moon given its present rotational and orbital state has been explained as due to a fossil figure preserving a record of remnant rotational and tidal deformation (Jeffreys, H. . Mem. R. Astron. Soc. 60, 187-217; Lambeck, K., Pullan, S. . Phys. Earth Planet. Interiors 22, 29-35; Garrick-Bethell, I., Wisdom, J., Zuber, M.T. . Science 313, 652-655). However, previous studies assume infinite rigidity and ignore deformation due to changes in the rotational and orbital potentials as the Moon evolves to the present state. We interpret the global lunar figure with a physical model that takes into account this deformation. Although the Moon deforms in response to rotational and orbital changes, a fossil figure capable of explaining the observed figure can be preserved by an elastic lithosphere. © 2012 Elsevier Inc.
Venkatesh V.,University of Arkansas |
Brown S.A.,University of Arizona |
Bala H.,Indiana University Bloomington
MIS Quarterly: Management Information Systems | Year: 2013
Mixed methods research is an approach that combines quantitative and qualitative research methods in the same research inquiry. Such work can help develop rich insights into various phenomena of interest that cannot be fully understood using only a quantitative or a qualitative method. Notwithstanding the benefits and repeated calls for such work, there is a dearth of mixed methods research in information systems. Building on the literature on recent methodological advances in mixed methods research, we develop a set of guidelines for conducting mixed methods research in IS. We particularly elaborate on three important aspects of conducting mixed methods research: (1) appropriateness of a mixed methods approach; (2) development of meta-inferences (i.e., substantive theory) from mixed methods research; and (3) assessment of the quality of meta-inferences (i.e., validation of mixed methods research). The applicability of these guidelines is illustrated using two published IS papers that used mixed methods. Copyright © 2013 by the Management Information Systems Research Center (MISRC) of the University of Minnesota.
Bayraksan G.,University of Arizona |
Morton D.P.,University of Texas at Austin
Operations Research | Year: 2011
We develop a sequential sampling procedure for a class of stochastic programs. We assume that a sequence of feasible solutions with an optimal limit point is given as input to our procedure. Such a sequence can be generated by solving a series of sampling problems with increasing sample size, or it can be found by any other viable method. Our procedure estimates the optimality gap of a candidate solution from this sequence. If the point estimate of the optimality gap is sufficiently small according to our termination criterion, then we stop. Otherwise, we repeat with the next candidate solution from the sequence under an increased sample size. We provide conditions under which this procedure (i) terminates with probability one and (ii) terminates with a solution that has a small optimality gap with a prespecified probability. © 2011 INFORMS.
Rafelski J.,University of Arizona
Acta Physica Polonica B | Year: 2012
I review the foundational motivations which led us to the ultra relativistic heavy ion collision research at SPS, RHIC and now LHC: the quantum vacuum structure; the deconfined nature of the quark-gluon plasma (QGP) phase filling the Universe for the first 30 μs after the Big Bang; the origin of mass of stable matter; and the origin of flavor. The special roles of strangeness enhancement and strange antibaryon signature are highlighted. It is shown how hadron production can be used to determine the properties of QGP and how the threshold energy for QGP formation is determined.
Cohen M.X.,University of Amsterdam |
Cohen M.X.,University of Arizona
Current Biology | Year: 2011
The hippocampus and prefrontal cortex interact to support working memory (WM) and long-term memory [1-3]. Neurophysiologically, WM is thought to be subserved by reverberatory activity of distributed networks within the prefrontal cortex (PFC) [2, 4-8], which become synchronized with reverberatory activity in the hippocampus [1, 4]. This electrophysiological synchronization is difficult to study in humans because noninvasive electroencephalography (EEG) cannot measure hippocampus activity. Here, using a novel integration of EEG and diffusion-weighted imaging, it is shown that individuals with relatively stronger anatomical connectivity linking the hippocampus to the right ventrolateral PFC (ventral Brodmann area 46) exhibited slower frequency neuronal oscillations during a WM task. Furthermore, subjects with stronger hippocampus-PFC connectivity were better able to encode the complex pictures used in the WM task into long-term memory. These findings are consistent with models suggesting that electrophysiological oscillations provide a mechanism of long-range interactions  and link hippocampus-PFC structural connectivity to PFC rhythmic electrical dynamics and memory performance. More generally, these results highlight the importance of incorporating individual differences when linking structure and function to cognition. © 2011 Elsevier Ltd.
Downs R.T.,University of Arizona
Elements | Year: 2015
The rover Curiosity is conducting X-ray diffraction experiments on the surface of Mars using the CheMin instrument. The analyses enable identification of the major and minor minerals, providing insight into the conditions under which the samples were formed or altered and, in turn, into past habitable environments on Mars. The CheMin instrument was developed over a twenty-year period, mainly through the efforts of scientists and engineers from NASA and DOE. Results from the first four experiments, at the Rocknest, John Klein, Cumberland, and Windjana sites, have been received and interpreted. The observed mineral assemblages are consistent with an environment hospitable to Earth-like life, if it existed on Mars.
Galaskiewicz J.,University of Arizona
Journal of Supply Chain Management | Year: 2011
Social networks often exist among individuals who are boundary spanners in an interorganizational network. These relationships are critical in explaining why interorganizational networks are formed, disintegrate, and succeed or fail. Trust is central in most theories of social network effectiveness, and it should also be true in supply chain networks. This article proposes that supply chain architects consider supply chains that exhibit small world properties. This optimizes trust within the clique, but enables predictions and innovations to "hop" across cliques to other regions in the supply chain. The article concludes by proposing that networks should be studied over time and not as stagnant structures, and highlights a new methodology (SoNIA) for this. © 2011 Institute for Supply Management, Inc.™.
Lusch R.F.,University of Arizona
Journal of Supply Chain Management | Year: 2011
Shifting the dominant thinking of supply chain management toward the concepts of service, value cocreation, value propositions, operant resources, networks, service ecosystems and learning opens up many research opportunities and strategies for improved organizational performance. The emerging thought world of service-dominant logic is presented as a means to reframe supply chain scholarship and practice for increased relevance and impact. © 2011 Institute for Supply Management, Inc.™.
Mayhew C.G.,Robert Bosch GmbH |
Sanfelice R.G.,University of Arizona |
Teel A.R.,University of California at Santa Barbara
IEEE Transactions on Automatic Control | Year: 2011
It is well known that controlling the attitude of a rigid body is subject to topological constraints. We illustrate, with examples, the problems that arise when using continuous and (memoryless) discontinuous quaternion-based state-feedback control laws for global attitude stabilization. We propose a quaternion-based hybrid feedback scheme that solves the global attitude tracking problem in three scenarios: full state measurements, only measurements of attitude, and measurements of attitude with angular velocity measurements corrupted by a constant bias. In each case, the hybrid feedback is dynamic and incorporates hysteresis-based switching using a single binary logic variable for each quaternion error state. When only attitude measurements are available or the angular rate is corrupted by a constant bias, the proposed controller is observer-based and incorporates an additional quaternion filter and bias observer. The hysteresis mechanism enables the proposed scheme to simultaneously avoid the unwinding phenomenon and sensitivity to arbitrarily small measurement noise that is present in discontinuous feedbacks. These properties are shown using a general framework for hybrid systems, and the results are demonstrated by simulation. © 2011 IEEE.
Jokipii J.R.,University of Arizona |
Lee M.A.,University of New Hampshire
Astrophysical Journal | Year: 2010
We present a new derivation of the acceleration of fast charged particles by random compressions and expansions based on a quasilinear approximation applied to the Parker transport equation, and explore its consequences. This process has been suggested in a recent series of papers by Fisk & Gloeckler (F&G) as the origin of the quiet-time suprathermal ion population observed throughout the inner heliosphere with an omnidirectional distribution function close to the form f(v)∞ v -5. Our derivation does not agree with a recent equation derived by F&G. We show that, while our equation conserves particles, the F&G equation does not. Solutions of the correct quasilinear equation are presented, which show that the compressive acceleration process does not produce power-law velocity spectra with indices less than (i.e., softer than) -3. We show that the transport equations for two other types of stochastic acceleration, by a spectrum of Alfvén waves and by transit-time damping of oblique magnetosonic waves, yield comparable acceleration rates but also do not produce power-law spectra with indices less than -3. Conversely, the process of diffusive shock acceleration, responsible for energetic storm particle events, corotating ion events and probably most large solar energetic particle (SEP) events, readily produces power-law velocity spectra with indices in a range including -5. It is suggested that the quiet-time suprathermal ion population is composed predominantly of remnant ions from these events as well as a contribution from impulsive SEP events. © 2010 The American Astronomical Society. All rights reserved.
Kieu K.,University of Arizona
IEEE Photonics Technology Letters | Year: 2010
We report a simple femtosecond fiber laser system based on a carbon nanotube saturable absorber that is capable of generating 14-fs pulses (containing less than four optical cycles) with optical spectrum extending from 1000 nm to around 1500 nm. © 2006 IEEE.
Kern K.B.,University of Arizona
Circulation Journal | Year: 2015
The post-cardiac arrest syndrome is a complex, multisystems response to the global ischemia and reperfusion injury that occurs with the onset of cardiac arrest, its treatment (cardiopulmonary resuscitation) and the re-establishment of spontaneous circulation. Regionalization of post-cardiac arrest care, utilizing specified cardiac arrest centers (CACs), has been proposed as the best solution to providing optimal care for those successfully resuscitated after out-of-hospital cardiac arrest. A multidisciplinary team of intensive care specialists, including critical care/pulmonologists, cardiologists (general, interventional, and electrophysiology), neurologists, and physical medicine/rehabilitation experts, is crucial for such centers. Particular attention to the timely initiation of targeted temperature management and early coronary angiography/percutaneous coronary intervention is best provided by such CACs. A State-wide program of CACs was started in Arizona in 2007. This is a voluntary program, whereby medical centers agree to provide all resuscitated cardiac arrest patients brought to their facility with state-of-the-art post-resuscitation care, including targeted temperature management for comatose patients and strong consideration for emergent coronary angiography for all patients with a likely cardiac etiology for their cardiac arrest. Survival improved by more than 50% at facilities that became CACs with a commitment to provide aggressive post-resuscitation care to all such patients. Providing aggressive, post-resuscitation care is the next real opportunity to increase long-term survival for cardiac arrest patients. © 2015, Japanese Circulation Society. All rights reserved.
Crimmins M.A.,University of Arizona
International Journal of Climatology | Year: 2011
Low-frequency changes (decades to years) in precipitation related to the El Niño-Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO) are known to influence wildfire variability across the southwest United States. Little work has been done to identify whether daily fire weather variability, also important to wildfire activity, is influenced by these same climatic phenomena. This study identifies the synoptic climatological conditions associated with extreme fire weather events in the Southwest and constructs an extreme fire weather frequency data set for the period of 1958-2003 using a logistic regression technique. Interannual changes in extreme fire weather day frequencies are not linearly correlated with either ENSO or PDO, but do show significant deviations from expected values when grouped by PDO phase (positive or negative) and further subgrouped by ENSO state (La Niña, El Niño or neutral). A higher number of extreme fire weather days occur during the negative phase of the PDO, especially when accompanied by a La Niña event. © 2010 Royal Meteorological Society.
Melia F.,Chinese Academy of Sciences |
Melia F.,University of Arizona
Astrophysical Journal | Year: 2013
One cannot understand the early appearance of 109 M ⊙ supermassive black holes without invoking anomalously high accretion rates or the creation of exotically massive seeds, neither of which is seen in the local universe. Recent observations have compounded this problem by demonstrating that most, if not all, of the high-z quasars appear to be accreting at the Eddington limit. In the context of ΛCDM, the only viable alternative now appears to be the assemblage of supermassive black holes via mergers, as long as the seeds started forming at redshifts >40, but ceased being created by z ∼ 20-30. In this paper, we show that, whereas the high-z quasars may be difficult to explain within the framework of the standard model, they can instead be interpreted much more sensibly in the context of the R h = ct universe. In this cosmology, 5-20 M⊙ seeds produced after the onset of re-ionization (at z ≲ 15) could have easily grown to M ≳ 109 M⊙ by z ≳ 6, merely by accreting at the standard Eddington rate. © 2013. The American Astronomical Society. All rights reserved.
Herman E.M.,University of Arizona
Frontiers in Plant Science | Year: 2014
The soybean seed's protein content and composition are regulated by both genetics and physiology. Overt seed protein content is specified by the genotype's genetic framework and is selectable as a breeding trait. Within the genotype-specified protein content phenotype soybeans have the capacity to rebalance protein composition to create differing proteomes. Soybeans possess a relatively standardized proteome, but mutation or targeted engineering can induce large-scale proteome rebalancing. Proteome rebalancing shows that the output traits of seed content and composition result from two major types of regulation: genotype and post-transcriptional control of the proteome composition. Understanding the underlying mechanisms that specifies the seed proteome can enable engineering new phenotypes for the production of a high-quality plant protein source for food, feed, and industrial proteins. © 2014 Herman.
Liu B.,Peking University |
Showman A.P.,University of Arizona
Astrophysical Journal | Year: 2013
The ongoing characterization of hot Jupiters has motivated a variety of circulation models of their atmospheres. Such models must be integrated starting from an assumed initial state, which is typically taken to be a wind-free, rest state. Here, we investigate the sensitivity of hot-Jupiter atmospheric circulation to initial conditions with shallow-water models and full three-dimensional models. Those models are initialized with zonal jets, and we explore a variety of different initial jet profiles. We demonstrate that, in both classes of models, the final, equilibrated state is independent of initial condition - as long as frictional drag near the bottom of the domain and/or interaction with a specified planetary interior are included so that the atmosphere can adjust angular momentum over time relative to the interior. When such mechanisms are included, otherwise identical models initialized with vastly different initial conditions all converge to the same statistical steady state. In some cases, the models exhibit modest time variability; this variability results in random fluctuations about the statistical steady state, but we emphasize that, even in these cases, the statistical steady state itself does not depend on initial conditions. Although the outcome of hot-Jupiter circulation models depend on details of the radiative forcing and frictional drag, aspects of which remain uncertain, we conclude that the specification of initial conditions is not a source of uncertainty, at least over the parameter range explored in most current models. © 2013. The American Astronomical Society. All rights reserved.
Kota J.,University of Arizona
Astrophysical Journal | Year: 2010
Particle acceleration at two-dimensional (2D) shocks can significantly differ from our expectations based on onedimensional shocks. We discuss several features of 2D shocks. First, we present a simple example of diffusive acceleration to demonstrate that (1) "hot spots" and cold regions can be expected along the shock face, as the field-line configuration changes along the shock face, (2) the flux of accelerated particles (even the average flux) can be expected to increase beyond the shock, and (3) 2D structures may lead to a softening of the spectrum. We also address quasi-perpendicular shocks and discuss what happens when a field line is hit by a curved shock or is detaching from a shock. This mechanism is of interest on both large and small scales. We consider pure field-aligned transport and address both the diffusive (large scale) and scatter-free (small scale) cases, looking from the perspective of one field line. We find that quasi-trapping of particles in front of the shock can lead to rapid and effective acceleration via multiple mirroring on the ever faster moving shock. This mechanism may be of importance at various astrophysical, heliospheric, and coronal mass ejection driven shocks. © 2010. The American Astronomical Society.
Giacalone J.,University of Arizona |
Decker R.,Johns Hopkins Applied Physics Laboratory
Astrophysical Journal | Year: 2010
We address the origin of the enhancement of ∼ 40keV to 5 MeV ions at the solar wind termination shock. Using self-consistent two-dimensional hybrid simulations (kinetic proton, fluid electron) of a shock moving through a plasma similar to that observed in the outer heliosphere, we conclude that the observed ion enhancements are consistent with accelerated "core" interstellar pickup ions (those that have not previously undergone any significant energization) by the termination shock via a combination of shock drift acceleration and particle scattering in meandering magnetic fields in the vicinity of the shock. In addition to the consequences for our understanding of anomalous cosmic rays, this work is also relevant to the more-general long-standing problem of accelerating low-energy particles by shocks that move nearly normal to a mean magnetic field. © 2010. The American Astronomical Society. All rights reserved.
Grau R.G.,University of Arizona
Current Rheumatology Reports | Year: 2015
An increasing number of therapeutic agents have been associated with a vasculitic syndrome. This usually involves small vessels, primarily capillaries, venules, and arterioles in leukocytoclastic vasculitis, small-vessel disease similar to an antineutrophil cytoplasmic antibody-related vasculitis, or mid-sized muscular arteries in a polyarteritis-like picture. Antineutrophil cytoplasmic antibodies are present in many cases of vasculitis regardless of the size of the vessel involved. Monoclonal antibodies used to treat many autoimmune disorders have become the most common agents associated with drug-induced vasculitis. Important advances in epigenetics, genetics, and neutrophil apoptosis are providing new insights into the pathogenesis of both drug-induced vasculitis and idiopathic vasculitis. Although management has not changed significantly in the past few years where withdrawal of the offending agent is the primary intervention, increasing awareness of drug-induced vasculitis can lead to earlier diagnosis and prevention of severe organ damage and fatalities. © 2015, Springer Science+Business Media New York.
Crogan N.L.,University of Arizona
Journal of the American Medical Directors Association | Year: 2011
Objective: The purpose of this article was to describe the pilot testing of the Sorbet Increases Salivation (SIS) intervention and describe its impact on salivation and subsequent resident food intake. Methods: Using a repeated treatment design with each elder serving as his or her own control, 12 elders were served 2 ounces of sugar-free lemon-lime sorbet just before the lunch meal for two 3-week periods separated by a 6-week observation (no treatment) period. A plate waste protocol was used to determine actual food intake. Before the initiation of the intervention, salivation was measured (using a Modified Schirmer Test [MST] strip) at baseline and then at 1, 2, and 3 minutes of consuming 2 oz of sugar-free lemon-lime sorbet or 2 oz of water. Summary statistics (means, standard deviations, proportions) were used to describe the study sample. Bivariate statistics determined whether there were significant differences between MST measures or food intake within subjects. Results: Salivation significantly increased after consuming sorbet or water. Most importantly, residents who consumed sorbet salivated more on average in comparison with residents who consumed water. During pilot testing, most residents consumed more food on average during treatment weeks in comparison with observation weeks. Conclusion: The intervention has the potential to increase salivation, decrease complaints of xerostomia, and increase food intake in institutionalized elders with drug-induced xerostomia. The new knowledge gained from this study will lead to further research and testing of the intervention with the long-term goal of transforming the " care-as-usual" approach to meal service in nursing homes. © 2011 American Medical Directors Association.
Djordjevic I.B.,University of Arizona
Optics Express | Year: 2011
In order to achieve multi-gigabit transmission (projected for 2020) for the use in interplanetary communications, the usage of large number of time slots in pulse-position modulation (PPM), typically used in deep-space applications, is needed, which imposes stringent requirements on system design and implementation. As an alternative satisfying high-bandwidth demands of future interplanetary communications, while keeping the system cost and power consumption reasonably low, in this paper, we describe the use of orbital angular momentum (OAM) as an additional degree of freedom. The OAM is associated with azimuthal phase of the complex electric field. Because OAM eigenstates are orthogonal the can be used as basis functions for N-dimensional signaling. The OAM modulation and multiplexing can, therefore, be used, in combination with other degrees of freedom, to solve the high-bandwidth requirements of future deep-space and near-Earth optical communications. The main challenge for OAM deep-space communication represents the link between a spacecraft probe and the Earth station because in the presence of atmospheric turbulence the orthogonality between OAM states is no longer preserved. We will show that in combination with LDPC codes, the OAM-based modulation schemes can operate even under strong atmospheric turbulence regime. In addition, the spectral efficiency of proposed scheme is N2/log2N times better than that of PPM. © 2011 Optical Society of America.
Doshi S.,University of Arizona
Antipode | Year: 2013
In recent years cities around the world have undergone mass slum clearances for redevelopment. This study of Mumbai offers an alternative interpretation of urban capital accumulation by investigating the differentiated political subjectivities of displaced slum residents. I argue that Mumbai's redevelopment entails not uniform class-based dispossessions but a process of accumulation by differentiated displacement whereby uneven displacement politics are central to the social production of land markets. Two ethnographic cases reveal that groups negotiate redevelopment in contradictory ways, supporting or contesting projects in varying moments. Redevelopmental subjectivities are influenced at key conjunctures by market-oriented resettlement, ideologies of belonging, desires for improved housing, and participation in non-governmental groups. This articulated assemblage of power-laden practices reflects and reworks class, gender, and ethno-religious relations, profoundly shaping evictees' experience and political engagement. The paper concludes that focusing on differentiated subjectivities may usefully guide both analysis and social justice practice aimed at countering dispossession. © 2013 The Author. Antipode © 2013 Antipode Foundation Ltd.
Baker V.R.,University of Arizona
Geomorphology | Year: 2015
Three broad themes from the history of planetary geomorphology provide lessons in regard to the logic (valid reasoning processes) for the doing of that science. The long controversy over the origin of lunar craters, which was dominated for three centuries by the volcanic hypothesis, provides examples of reasoning on the basis of authority and a priori presumptions. Percival Lowell's controversy with geologists over the nature of linear markings on the surface of Mars illustrates the role of tenacity in regard to the beliefs of some individual scientists. Finally, modern controversies over the role of water in shaping the surface of Mars illustrate how the a priori method, i.e., belief produced according to reason, can seductively cloud the scientific openness to the importance of brute facts that deviate from a prevailing paradigm. © 2014 Elsevier B.V.
Peng Y.,University of Arizona
Molecular Psychiatry | Year: 2016
The human MET gene imparts a replicated risk for autism spectrum disorder (ASD), and is implicated in the structural and functional integrity of brain. MET encodes a receptor tyrosine kinase, MET, which has a pleiotropic role in embryogenesis and modifies a large number of neurodevelopmental events. Very little is known, however, on how MET signaling engages distinct cellular events to collectively affect brain development in ASD-relevant disease domains. Here, we show that MET protein expression is dynamically regulated and compartmentalized in developing neurons. MET is heavily expressed in neuronal growth cones at early developmental stages and its activation engages small GTPase Cdc42 to promote neuronal growth, dendritic arborization and spine formation. Genetic ablation of MET signaling in mouse dorsal pallium leads to altered neuronal morphology indicative of early functional maturation. In contrast, prolonged activation of MET represses the formation and functional maturation of glutamatergic synapses. Moreover, manipulating MET signaling levels in vivo in the developing prefrontal projection neurons disrupts the local circuit connectivity made onto these neurons. Therefore, normal time-delimited MET signaling is critical in regulating the timing of neuronal growth, glutamatergic synapse maturation and cortical circuit function. Dysregulated MET signaling may lead to pathological changes in forebrain maturation and connectivity, and thus contribute to the emergence of neurological symptoms associated with ASD.Molecular Psychiatry advance online publication, 5 January 2016; doi:10.1038/mp.2015.182. © 2016 Macmillan Publishers Limited
Zheng Y.-Z.,Xian University of Science and Technology |
Zhou G.-J.,Xian University of Science and Technology |
Zheng Z.,Xian University of Science and Technology |
Zheng Z.,University of Arizona |
Winpenny R.E.P.,University of Manchester
Chemical Society Reviews | Year: 2014
There has been a rapid expansion in the use of molecular magnets for both low- and ultra low-temperature cooling applications in recent years, and here we review the chemical variation and magnetothermal properties of reported molecular coolers, structuring the review by structural dimensions, metal-ions involved and ligands employed. This review provides an overview of the developments in designing better low-temperature magnetic refrigerants, and includes description of new 3D-materials that, in some ways, out-perform traditional magnetic coolants. Thus, this review should serve as both a tutorial for many newcomers and a summary of progress for researchers who are active in the field. © 2014 The Royal Society of Chemistry.
Anderson B.P.,University of Arizona
Journal of Low Temperature Physics | Year: 2010
Observations of quantized vortices in dilute-gas Bose-Einstein condensates were first reported in 1999. Over the next 10 years, more than 70 papers describing experiments involving vortices in superfluid atomic gases were published in scientific journals. This resource article provides a guide to the published experimental studies related to quantized vortices in atomic Bose-Einstein condensates and superfluid Fermi gases. A BibTex-formatted bibliography document listing these published studies is also available electronically. © Springer Science+Business Media, LLC 2010.
Yao G.,University of Arizona
Interface Focus | Year: 2014
Cellular quiescence is a reversible non-proliferating state. The reactivation of 'sleep-like' quiescent cells (e.g. fibroblasts, lymphocytes and stem cells) into proliferation is crucial for tissue repair and regeneration and a key to the growth, development and health of higher multicellular organisms, such as mammals. Quiescence has been a primarily phenotypic description (i.e. non-permanent cell cycle arrest) and poorly studied. However, contrary to the earlier thinking that quiescence is simply a passive and dormant state lacking proliferating activities, recent studies have revealed that cellular quiescence is actively maintained in the cell and that it corresponds to a collection of heterogeneous states. Recent modelling and experimental work have suggested that an Rb-E2F bistable switch plays a pivotal role in controlling the quiescence-proliferation balance and the heterogeneous quiescent states. Other quiescence regulatory activities may crosstalk with and impinge upon the Rb-E2F bistable switch, forming a gene network that controls the cells' quiescent states and their dynamic transitions to proliferation in response to noisy environmental signals. Elucidating the dynamic control mechanisms underlying quiescence may lead to novel therapeutic strategies that re-establish normal quiescent states, in a variety of hyperand hypo-proliferative diseases, including cancer and ageing. © 2014 The Author(s) Published by the Royal Society. All rights reserved.
Jackson S.T.,U.S. Geological Survey |
Jackson S.T.,University of Arizona |
Blois J.L.,University of California at Merced
Proceedings of the National Academy of Sciences of the United States of America | Year: 2015
Community ecology and paleoecology are both concerned with the composition and structure of biotic assemblages but are largely disconnected. Community ecology focuses on existing species assemblages and recently has begun to integrate history (phylogeny and continental or intercontinental dispersal) to constrain community processes. This division has left a "missing middle": Ecological and environmental processes occurring on timescales from decades to millennia are not yet fully incorporated into community ecology. Quaternary paleoecology has a wealth of data documenting ecological dynamics at these timescales, and both fields can benefit from greater interaction and articulation. We discuss ecological insights revealed by Quaternary terrestrial records, suggest foundations for bridging between the disciplines, and identify topics where the disciplines can engage to mutual benefit. © 2015, National Academy of Sciences. All rights reserved.
Caselli R.J.,Mayo Medical School |
Reiman E.M.,University of Arizona
Journal of Alzheimer's Disease | Year: 2013
Studies of asymptomatic carriers of genes that are known to predispose to Alzheimer's disease (AD) have facilitated the characterization of preclinical AD. The most prevalent genetic risk factor is the ε4 allele of apolipoprotein E (APOE). Neuropathological studies of young deceased ε4 carriers have shown modest but abnormal amounts of neocortical amyloid and medial temporal neurofibrillary tangles that is also reflected in cerebrospinal fluid (CSF) biomarkers, amyloid-β, and phospho-tau in particular. MRI studies have shown progressive hippocampal and gray matter atrophy with the advent of mild cognitive impairment (MCI), and fluorodeoxyglucose PET scans show reduced cerebral metabolism in posterior cingulate and related AD regions evident even in 30 year olds. Cerebral amyloidosis disclosed by more recent amyloid ligand PET studies in asymptomatic 60 year olds increases in parallel with ε4 gene dose. Longitudinal neuropsychological studies have revealed accelerated memory decline in ε4 carriers beginning around age 55-60 years whose severity again parallels ε4 gene dose. The clinico-pathological correlation of declining memory and AD-like neuropathological change defines preclinical AD and has set the stage for the accelerated evaluation of presymptomatic AD treatments. In this article, we briefly consider some of the earliest detectable changes associated with the predisposition to AD, and some of the prevention trial strategies that have been proposed to help find treatments to reduce the risk, postpone the onset of, or completely prevent AD symptoms as soon as possible. © 2013 - IOS Press and the authors. All rights reserved.
Enright P.L.,University of Arizona
Respiratory Care | Year: 2012
Professional societies have encouraged primary care providers to conduct spirometry testing for the detection of chronic obstructive pulmonary disease (COPD). In spite of this effort, the success rate is unacceptably low. Simple flow-sensing spirometers have technical flaws that can cause misreadings, and they are rarely checked for accuracy. When spirometry is performed by an experienced technologist, and when payment is made on the criterion of quality, the success rate for adults and school-aged children can be as high as 90%. But testing remains a challenge for younger children and the elderly. Regular feedback for the technologist about their testing results is essential. Even with an accurate spirometer, an able patient, and a skilled technologist, the ordering physician may wrongly interpret the data. Use of spirometry in primary care will continue to be problematic unless high quality testing is tied to reimbursement. Using FEV 1 or peak flow measurements to rule out airway abnormality in the majority of patients, followed by referral for more sophisticated studies in those remaining, may be the best approach. Respiratory therapists should engage in this effort. © 2012 Daedalus Enterprises.
Brusseau M.L.,University of Arizona
Water, Air, and Soil Pollution | Year: 2013
Groundwater withdrawal and contaminant concentration data are routinely collected for pumpand-treat operations conducted at hazardous waste sites. These data sets can be mined to produce a wealth of information to support enhanced site characterization, optimization of remedial system operations, and improved decision making regarding long-term site management and closure. Methods that may be used to analyze and interpret pump-and-treat data to produce such assessments are presented, along with a brief illustration of their application to a site. The results presented herein illustrate that comprehensive analysis of pump-and-treat data is a powerful, cost-effective method for providing higher-resolution, value-added characterization of contaminated sites. © Springer Science+Business Media Dordrecht 2013.
Melia F.,University of Arizona
Astronomy and Astrophysics | Year: 2013
Context. The horizon problem in the standard model of cosmology (λDCM) arises from the observed uniformity of the cosmic microwave background radiation, which has the same temperature everywhere (except for tiny, stochastic fluctuations), even in regions on opposite sides of the sky, which appear to lie outside of each other's causal horizon. Since no physical process propagating at or below lightspeed could have brought them into thermal equilibrium, it appears that the universe in its infancy required highly improbable initial conditions. Aims. In this paper, we demonstrate that the horizon problem only emerges for a subset of Friedmann-Robertson-Walker (FRW) cosmologies, such as λCDM, that include an early phase of rapid deceleration. Methods. The origin of the problem is examined by considering photon propagation through a FRWspacetime at a more fundamental level than has been attempted before. Results. We show that the horizon problem is nonexistent for the recently introduced Rh = ct universe, obviating the principal motivation for the inclusion of inflation. We demonstrate through direct calculation that, in this cosmology, even opposite sides of the cosmos have remained causally connected to us - and to each other - from the very first moments in the universe's expansion. Therefore, within the context of the R h = ct universe, the hypothesized inflationary epoch from t = 10 -35 s to 10-32 s was not needed to fix this particular "problem", though it may still provide benefits to cosmology for other reasons. © ESO 2013.
Songer J.G.,University of Arizona
Veterinary Microbiology | Year: 2010
Clostridia are not normally considered to be zoonotic pathogens, although many species affect both humans and domestic animals. Three cases in which organisms occur, possibly via direct or indirect transmission, in both food animals and humans are considered here. Strains of Clostridium perfringens that produce enterotoxin (CPE) are typically transmitted to humans in contaminated, improperly handled foods. Pathogenesis is based upon action of CPE in the intestine, and disease is usually self-limiting. Infection of domestic animals by CPE-producing C. perfringens is uncommon. C. perfringens type C is best known as a pathogen of neonatal domestic animals, which acquire the infection from the dam. The course may be peracute, and prevention by vaccination of the dam is universally advocated. Humans consuming meat contaminated with type C may develop enteritis necroticans, with segmental hemorrhagic and necrotic jejunitis, which must usually be treated by bowel resection. Clostridium difficile is a pathogen of both humans and domestic animals. Examination of retail meats by bacteriologic culture has revealed genotypes of C. difficile that in many cases are identical to those from food animals and diseased humans. Transmission, food animals to foods to humans, has not been documented. © 2009 Elsevier B.V. All rights reserved.
Talanquer V.,University of Arizona
Journal of Chemical Education | Year: 2013
The chemistry knowledge that we want our students to develop is rich, complex, and multifaceted. However, some teachers and instructors at the secondary school and college levels approach it in rather rigid and unidimensional ways. The central goal of this contribution is to describe and discuss 10 different complementary perspectives or "facets" from which chemistry content in introductory courses can be analyzed. This multidimensional view may help chemical educators, particularly those who are new to the profession, enrich their understanding of chemistry as a teaching subject and open the path for diverse reconceptualizations of the chemistry curriculum. © 2013 The American Chemical Society and Division of Chemical Education, Inc.
Burke G.R.,University of Arizona |
Moran N.A.,Yale University
Genome Biology and Evolution | Year: 2011
All vertically transmitted bacterial symbionts undergo a process of genome reduction over time, resulting in tiny, gene-dense genomes. Comparison of genomes of ancient bacterial symbionts gives only limited information about the early stages in the transition from a free-living to symbiotic lifestyle because many changes become obscured over time. Here, we present the genome sequence for the recently evolved aphid symbiont Serratia symbiotica. The S. symbiotica genome exhibits several of the hallmarks of genome evolution observed in more ancient symbionts, including elevated rates of evolution and reduction in genome size. The genome also shows evidence for massive genomic decay compared with free-living relatives in the same genus of bacteria, including large deletions, many pseudogenes, and a slew of rearrangements, perhaps promoted by mobileDNA. Annotation of pseudogenes allowed examination of the past and current metabolic capabilities of S. symbiotica and revealed a somewhat random process of gene inactivation with respect to function. Analysis of mutational patterns showed that deletions are more common in neutral DNA. The S. symbiotica genome provides a rare opportunity to study genome evolution in a recently derived heritable symbiont. © The Author(s) 2011.
Yun S.,University of Arizona |
Vincelette N.D.,Molecular Therapeutics
Critical Reviews in Oncology/Hematology | Year: 2015
Iron is an essential component of erythropoiesis and its metabolism is tightly regulated by a variety of internal and external cues including iron storage, tissue hypoxia, inflammation and degree of erythropoiesis. There has been remarkable improvement in our understanding of the molecular mechanisms of iron metabolism past decades. The classical model of iron metabolism with iron response element/iron response protein (IRE/IRP) is now extended to include hepcidin model. Endogenous and exogenous signals funnel down to hepcidin via wide range of signaling pathways including Janus Kinase/Signal Transducer and Activator of Transcription 3 (JAK/STAT3), Bone Morphogenetic Protein/Hemojuvelin/Mothers Against Decapentaplegic Homolog (BMP/HJV/SMAD), and Von Hippel Lindau/Hypoxia-inducible factor/Erythropoietin (VHL/HIF/EPO), then relay to ferroportin, which directly regulates intra- and extracellular iron levels. The successful molecular delineation of iron metabolism further enhanced our understanding of common genetic and acquired disorder, hemochromatosis. The majority of the hereditary hemochromatosis (HH) patients are now shown to have mutations in the genes coding either upstream or downstream proteins of hepcidin, resulting in iron overload. The update on hepcidin centered mechanisms of iron metabolism and their clinical perspective in hemochromatosis will be discussed in this review. © 2015 Elsevier Ireland Ltd.
MacK D.J.,Cornell University |
Njardarson J.T.,University of Arizona
Angewandte Chemie - International Edition | Year: 2013
Building with berries! Several labdane natural products have been synthesized for the first time by the combination of a copper-catalyzed vinyl oxirane ring expansion reaction with an abundant, inexpensive, chiral natural source (juniper berries; see scheme). These expedient (1-5 step) syntheses have resulted in the structural confirmations of five natural products and one reassignment. Reagent-controlled oxidation and 1,3-diene isomerization results are also presented. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Pelletier J.D.,University of Arizona
Water Resources Research | Year: 2013
In this article, a method for drainage network extraction from high-resolution digital elevation models (DEMs; e.g., those derived from airborne laser swath mapping) is presented, which requires just two user-defined parameters and is capable of handling discontinuous valley networks. The accuracy and robustness of the method are illustrated using synthetic valley networks that mimic the complexities of real landscapes and for which the true drainage network is known exactly by construction. The method involves six principal steps: optimal Wiener filtering to remove microtopographic noise, mapping of the contour curvature, identification of valley heads using a user-defined contour-curvature threshold criterion, routing of a unit discharge of water from each valley head using a multiple-flow-direction routing algorithm, removal of discontinuous reaches from the drainage network using a user-defined discharge-per-upstream-valley-head threshold criterion, and thinning of the valley network to a single pixel width. The method yields accurate results using the same user-defined parameters for the two field sites considered in this study, suggesting that for DEMs with resolution of approximately 1 m, the method has the ability to produce accurate results for a variety of landscapes by using the same parameter values used in this study. © 2013. American Geophysical Union. All Rights Reserved.
Chalmers D.J.,University of Arizona
Annals of the New York Academy of Sciences | Year: 2013
This chapter gives an overview of the projects facing a science of consciousness. Such a science must integrate third-person data about behavior and brain processes with first-person data about conscious experience. Empirical projects for integrating these data include those of contrasting conscious and unconscious processes, investigating the contents of consciousness, finding neural correlates of consciousness, and eventually inferring underlying principles connecting consciousness with physical processes. These projects are discussed with reference to current experimental research on consciousness. Some obstacles that a science of consciousness faces are also discussed. © 2013 New York Academy of Sciences.
Hubbard W.B.,University of Arizona
Astrophysical Journal | Year: 2013
I present exact expressions for the interior gravitational potential V of a system of N concentric constant-density (Maclaurin) spheroids. I demonstrate an iteration procedure to find a self-consistent solution for the shapes of the interfaces between spheroids, and for the interior gravitational potential. The external free-space potential, expressed as a multipole expansion, emerges as part of the self-consistent solution. The procedure is both simpler and more precise than perturbation methods. One can choose the distribution and mass densities of the concentric spheroids so as to reproduce a prescribed barotrope to a specified accuracy. I demonstrate the method's efficacy by comparing its results with several published test cases. © 2013. The American Astronomical Society. All rights reserved.
Schwartz S.D.,University of Arizona
Topics in Current Chemistry | Year: 2013
This chapter discusses progress over the past 15 years in understanding the role of protein dynamics in enzymatically catalyzed chemical reactions. Research has shown that protein motion on all timescales from femtoseconds to milliseconds can contribute to function, and in particular in some enzymes there are sub-picosecond motions, on the same timescale as barrier passage, the couple directly to chemical transformation, and are thus part of the reaction coordinate. Approaches such as transition path sampling and committor analysis have greatly enhanced our understanding of these processes. © Springer-Verlag Berlin Heidelberg 2013.
Ayyalasomayajula A.,University of Arizona
Journal of biomechanical engineering | Year: 2010
Abdominal aortic aneurysm (AAA) is the gradual weakening and dilation of the infrarenal aorta. This disease is progressive, asymptomatic, and can eventually lead to rupture--a catastrophic event leading to massive internal bleeding and possibly death. The mechanical environment present in AAA is currently thought to be important in disease initiation, progression, and diagnosis. In this study, we utilize porohyperelastic (PHE) finite element models (FEMs) to investigate how such modeling can be used to better understand the local biomechanical environment in AAA. A 3D hypothetical AAA was constructed with a preferential anterior bulge assuming both the intraluminal thrombus (ILT) and the AAA wall act as porous materials. A parametric study was performed to investigate how physiologically meaningful variations in AAA wall and ILT hydraulic permeabilities affect luminal interstitial fluid velocities and wall stresses within an AAA. A corresponding hyperelastic (HE) simulation was also run in order to be able to compare stress values between PHE and HE simulations. The effect of AAA size on local interstitial fluid velocity was also investigated by simulating maximum diameters (5.5 cm, 4.5 cm, and 3.5 cm) at the baseline values of ILT and AAA wall permeability. Finally, a cyclic PHE simulation was utilized to study the variation in local fluid velocities as a result of a physiologic pulsatile blood pressure. While the ILT hydraulic permeability was found to have minimal affect on interstitial velocities, our simulations demonstrated a 28% increase and a 20% decrease in luminal interstitial fluid velocity as a result of a 1 standard deviation increase and decrease in AAA wall hydraulic permeability, respectively. Peak interstitial velocities in all simulations occurred on the luminal surface adjacent to the region of maximum diameter. These values increased with increasing AAA size. PHE simulations resulted in 19.4%, 40.1%, and 81.0% increases in peak maximum principal wall stresses in comparison to HE simulations for maximum diameters of 35 mm, 45 mm, and 55 mm, respectively. The pulsatile AAA PHE FEM demonstrated a complex interstitial fluid velocity field the direction of which alternated in to and out of the luminal layer of the ILT. The biomechanical environment within both the aneurysmal wall and the ILT is involved in AAA pathogenesis and rupture. Assuming these tissues to be porohyperelastic materials may provide additional insight into the complex solid and fluid forces acting on the cells responsible for aneurysmal remodeling and weakening.
Handa R.J.,University of Arizona |
Weiser M.J.,DSM Nutritional Products Inc.
Frontiers in Neuroendocrinology | Year: 2014
The hypothalamo-pituitary-adrenal (HPA) axis represents a complex neuroendocrine feedback loop controlling the secretion of adrenal glucocorticoid hormones. Central to its function is the paraventricular nucleus of the hypothalamus (PVN) where neurons expressing corticotropin releasing factor reside. These HPA motor neurons are a primary site of integration leading to graded endocrine responses to physical and psychological stressors. An important regulatory factor that must be considered, prior to generating an appropriate response is the animal's reproductive status. Thus, PVN neurons express androgen and estrogen receptors and receive input from sites that also express these receptors. Consequently, changes in reproduction and gonadal steroid levels modulate the stress response and this underlies sex differences in HPA axis function. This review examines the make up of the HPA axis and hypothalamo-pituitary-gonadal (HPG) axis and the interactions between the two that should be considered when exploring normal and pathological responses to environmental stressors. © 2013 Elsevier Inc.
Pannabecker T.L.,University of Arizona
Comprehensive Physiology | Year: 2012
The thin limbs of the loop of Henle, which comprise the intermediate segment, connect the proximal tubule to the distal tubule and lie entirely within the renal medulla. The descending thin limb consists of at least two or three morphologically and functionally distinct subsegments and participates in transepithelial transport of NaCl, urea, and water. Only one functionally distinct segment is recognized for the ascending thin limb, which carries out transepithelial transport of NaCl and urea in the reabsorptive and/or secretory directions. Membrane transporters involved with passive transcellular Cl, urea, and water fluxes have been characterized for thin limbs; however, these pathways do not account for all transepithelial fluid and solute fluxes that have been measured in vivo. The paracellular pathway has been proposed to play an important role in transepithelial Na and urea fluxes in defined thin-limb subsegments. As the transport pathways become clearer, the overall function of the thin limbs is becoming better understood. Primary and secondary signaling pathways and protein-protein interactions are increasingly recognized as important modulators of thin-limb cell function and cell metabolism. These functions must be investigated under diverse extracellular conditions, particularly for those cells of the deep inner medulla that function in an environment of wide variation in hyperosmolality. Transgenic mouse models of several key water and solute transport proteins have provided significant insights into thin-limb function. An understanding of the overall architecture of the medulla, including juxtapositions of thin limbs with collecting ducts, thick ascending limbs, and vasa recta, is essential for understanding the role of the kidney in maintaining Na and water homeostasis, and for understanding the urine concentrating mechanism. © 2012 American Physiological Society.
Wyant J.C.,University of Arizona
Applied Optics | Year: 2013
The addition of electronics, computers, and software to interferometry has enabled enormous improvements in optical metrology. This paper discusses four areas in which computerized interferometric measurement improvements have been made in the measurement of surface shape and surface roughness: (a) The use of computer-generated holograms for the testing of aspheric optics, (b) phase-shifting interferometry for getting interferometric data into a computer so the data can be analyzed, (c) computerized interference microscopes, including multiple-wavelength and coherence scanning, for the precision measurement of surface microstructure, and (d) vibration-insensitive dynamic interferometers for enabling precise measurements in noncontrolled environments. © 2012 Optical Society of America.
Djordjevic I.B.,University of Arizona
Journal of Lightwave Technology | Year: 2012
Future Internet and Ethernet technologies will be affected by both limited bandwidth of information infrastructure and its high energy consumption. In order to solve both problems simultaneously, in this invited paper, we describe several hybrid coded-modulation (CM) schemes enabling multiterabit optical transport including spatial-domain-based CM, mode-multiplexed 4-D CM, and mode-multiplexed generalized orthogonal frequency division multiplexing. A common property of these CM schemes is the employment of optimized signal constellations, various degrees of freedom, and rate-adaptive coding. These modulation schemes are called hybrid as all available degrees of freedom are used for transmission over optical fibers including amplitude, phase, polarization, and orbital angular momentum. Since the channel capacity is a linear function in number of dimensions, by increasing the number of basis functions, we can dramatically improve the overall system capacity. The energy-consumption problem is tackled by properly designing multidimensional signal constellations such that transinformation is maximized, while taking the energy constraint into account. © 2012 IEEE.
Zhang D.D.,University of Arizona |
Zhang D.D.,Arizona Cancer Center
Antioxidants and Redox Signaling | Year: 2013
The targeted activation of nuclear factor erythroid-derived-2-like 2 (Nrf2) to alleviate symptoms of chronic kidney disease has recently garnered much attention. Unfortunately, the greatest clinical success to date, bardoxolone, failed in phase III clinical trial for unspecified safety reasons. The present letter to the editor discusses the clinical development of bardoxolone and explores potential reasons for the ultimate withdrawal from clinical trials. In particular, was the correct clinical indication pursued and would improved specificity have mitigated the safety concerns? Ultimately, it is concluded that the right clinical indication and heightened specificity will lead to successful Nrf2-based therapies. Therefore, the bardoxolone clinical results do not dampen enthusiasm for Nrf2-based therapies; rather it illuminates the clinical potential of the Nrf2 pathway as a drug target. Antioxid. Redox Signal. 19, 517-518. © Copyright 2013, Mary Ann Liebert, Inc. 2013.
Showman A.P.,University of Arizona |
Kaspi Y.,Weizmann Institute of Science
Astrophysical Journal | Year: 2013
A variety of observations provide evidence for vigorous motion in the atmospheres of brown dwarfs and directly imaged giant planets. Motivated by these observations, we examine the dynamical regime of the circulation in the atmospheres and interiors of these objects. Brown dwarfs rotate rapidly, and for plausible wind speeds, the flow at large scales will be rotationally dominated. We present three-dimensional, global, numerical simulations of convection in the interior, which demonstrate that at large scales, the convection aligns in the direction parallel to the rotation axis. Convection occurs more efficiently at high latitudes than low latitudes, leading to systematic equator-to-pole temperature differences that may reach ∼1 K near the top of the convection zone. The interaction of convection with the overlying, stably stratified atmosphere will generate a wealth of atmospheric waves, and we argue that, as in the stratospheres of planets in the solar system, the interaction of these waves with the mean flow will cause a significant atmospheric circulation at regional to global scales. At large scales, this should consist of stratified turbulence (possibly organizing into coherent structures such as vortices and jets) and an accompanying overturning circulation. We present an approximate analytic theory of this circulation, which predicts characteristic horizontal temperature variations of several to ∼50 K, horizontal wind speeds of ∼10-300 m s-1, and vertical velocities that advect air over a scale height in ∼105-106 s. This vertical mixing may help to explain the chemical disequilibrium observed on some brown dwarfs. Moreover, the implied large-scale organization of temperature perturbations and vertical velocities suggests that near the L/T transition, patchy clouds can form near the photosphere, helping to explain recent observations of brown-dwarf variability in the near-IR. © 2013. The American Astronomical Society. All rights reserved.
Perez-Becker D.,University of California at Berkeley |
Showman A.P.,University of Arizona
Astrophysical Journal | Year: 2013
Infrared light curves of transiting hot Jupiters present a trend in which the atmospheres of the hottest planets are less efficient at redistributing the stellar energy absorbed on their daysides - and thus have a larger day-night temperature contrast - than colder planets. To this day, no predictive atmospheric model has been published that identifies which dynamical mechanisms determine the atmospheric heat redistribution efficiency on tidally locked exoplanets. Here we present a shallow-water model of the atmospheric dynamics on synchronously rotating planets that explains why heat redistribution efficiency drops as stellar insolation rises. Our model shows that planets with weak friction and weak irradiation exhibit a banded zonal flow with minimal day-night temperature differences, while models with strong irradiation and/or strong friction exhibit a day-night flow pattern with order-unity fractional day-night temperature differences. To interpret the model, we develop a scaling theory which shows that the timescale for gravity waves to propagate horizontally over planetary scales, τwave, plays a dominant role in controlling the transition from small to large temperature contrasts. This implies that heat redistribution is governed by a wave-like process, similar to the one responsible for the weak temperature gradients in the Earth's tropics. When atmospheric drag can be neglected, the transition from small to large day-night temperature contrasts occurs when , where τrad is the radiative relaxation time and Ω is the planetary rotation frequency. Alternatively, this transition criterion can be expressed as τrad ∼ τvert, where τvert is the timescale for a fluid parcel to move vertically over the difference in day-night thickness. These results subsume the more widely used timescale comparison for estimating heat redistribution efficiency between τrad and the horizontal day-night advection timescale, τadv. Only because τadv ∼ τvert for hot Jupiters does the commonly assumed timescale comparison between τrad and τadv yield approximately correct predictions for the heat redistribution efficiency. © 2013. The American Astronomical Society. All rights reserved..
Goff S.A.,University of Arizona |
Zhang Q.,Huazhong Agricultural University
Current Opinion in Plant Biology | Year: 2013
Because of the tremendous advances in functional genomics and the current availability of a large number of superior hybrids, rice is an excellent model crop system for heterosis research. Genetic dissection of yield and yield component traits of an elite rice hybrid using an ultra-high density linkage map identified overdominance as the principal genetic basis of heterosis in this hybrid. This is not an expected finding based on the reported effects of single genes. Here we propose a gene expression and protein quality control hypothesis as one possible explanation for the overdominance in hybrids bred for yield. Future studies will be directed toward the identification of the genetic and biochemical mechanisms underlying the biology of hybrid vigor. © 2013 Elsevier Ltd.
Ampel N.M.,University of Arizona
Proceedings of the American Thoracic Society | Year: 2010
Coccidioidomycosis is a growing problem in the endemic regions of Arizona and California. The reasons for its increase are unclear, but may relate to an influx of nonsusceptible individuals into the endemic regions, construction and dust, and climate. Most cases of coccidioidal infection are completely asymptomatic, but approximately 40% present as a pulmonary process that may be difficult to distinguish from a bacterial community-acquired pneumonia. This has led to underdiagnosis of coccidioidomycosis and inappropriate antibacterial therapy. Serology has been the mainstay of diagnosis, but its sensitivity has not been established. A commercial enzyme immunoassay appears more sensitive than the traditional tube precipitin and complement fixation tests and the immunodiffusion assays, but concern about specificity lingers. Newer tests, including detection of coccidioidal antigenuria and genomic assays, offer promise of greater sensitivity, specificity, and rapidity. The treatment of coccidioidomycosis has most recently depended on oral triazole therapy. However, a recent study suggests that, at least for those with primary pulmonary disease, antifungal therapy may lead to subsequent complications once this therapy is discontinued compared with those who receive no therapy at all.
Badyaev A.V.,University of Arizona
Journal of Physiology | Year: 2014
The age of most genes exceeds the longevity of their genomic and physiological associations by many orders of magnitude. Such transient contexts modulate the expression of ancient genes to produce currently appropriate and often highly distinct developmental and functional outcomes. The efficacy of such adaptive modulation is diminished by the high dimensionality of complex organisms and associated vast areas of neutrality in their genotypic and developmental networks (and, thus, weak natural selection). Here I explore whether epigenetic effects facilitate adaptive modulation of complex phenotypes by effectively reducing the dimensionality of their deterministic networks and thus delineating their developmental and evolutionary trajectories even under weak selection. Epigenetic effects that link unconnected or widely dispersed elements of genotype space in ecologically relevant time could account for the rapid appearance of functionally integrated adaptive modifications. On an organismal time scale, conceptually similar processes occur during recurrent epigenetic reprogramming of somatic stem cells to produce, recurrently and reversibly, a bewildering array of differentiated and persistent cell lineages, all sharing identical genomic sequences despite strongly distinct phenotypes. I discuss whether close dependency of onset, scope and duration of epigenetic effects on cellular and genomic context in stem cells could provide insights into contingent modulation of conserved genomic material on a much longer evolutionary time scale. I review potential empirical examples of epigenetic bridges that reduce phenotype dimensionality and accomplish rapid adaptive modulation in the evolution of novelties, expression of behavioural types, and stress-induced ossification schedules. © 2014 The Physiological Society.
Militzer B.,University of California at Berkeley |
Hubbard W.B.,University of Arizona
Astrophysical Journal | Year: 2013
Using density functional molecular dynamics simulations, we determine the equation of state (EOS) for hydrogen-helium mixtures spanning density-temperature conditions typical of giant-planet interiors, ∼0.2-9 g cm-3 and 1000-80,000 K for a typical helium mass fraction of 0.245. In addition to computing internal energy and pressure, we determine the entropy using an ab initio thermodynamic integration technique. A comprehensive EOS table with 391 density-temperature points is constructed and the results are presented in the form of a two-dimensional free energy fit for interpolation. Deviations between our ab initio EOS and the semi-analytical EOS model by Saumon and Chabrier are analyzed in detail, and we use the results for initial revision of the inferred thermal state of giant planets with known values for mass and radius. Changes are most pronounced for planets in the Jupiter mass range and below. We present a revision to the mass-radius relationship that makes the hottest exoplanets increase in radius by ∼0.2 Jupiter radii at fixed entropy and for masses greater than ∼0.5 Jupiter mass. This change is large enough to have possible implications for some discrepant "inflated giant exoplanets." © 2013. The American Astronomical Society. All rights reserved.
Christensen N.,University of Pittsburgh |
Han T.,University of Pittsburgh |
Su S.,University of Arizona
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2012
The recent results on Higgs boson searches from LHC experiments provide significant guidance in exploring the minimal supersymmetric (SUSY) standard model (MSSM) Higgs sector. If we accept the existence of a SM-like Higgs boson in the mass window of 123 GeV-127 GeV as indicated by the observed γγ events, there are two distinct mass regions (in m A) left in the MSSM Higgs sector: (a) the lighter CP-even Higgs boson being SM-like and the non-SM-like Higgs bosons all heavy and nearly degenerate above 300 GeV (an extended decoupling region); (b) the heavier CP-even Higgs boson being SM-like and the neutral non-SM-like Higgs bosons all nearly degenerate around 100 GeV (a small non-decoupling region). On the other hand, due to the strong correlation between the Higgs decays to W +W - and to γγ predicted in the MSSM, the apparent absence of a W +W - final state signal is in direct conflict with the γγ peak. If we consider the W +W - channel on its own, the absence of the W +W - signal would imply that the SM-like Higgs boson has reduced coupling to W ±, and that the other non-SM-like Higgs bosons should not be too heavy and do not decouple. If both the γγ excess and the absence of a W +W - signal continue, new physics beyond the MSSM will be required. A similar correlation exists between the W +W - and τ +τ - channels: a reduced W +W - channel would force the τ +τ - channel to be larger. Future searches for the SM-like Higgs boson at the LHC will provide critical tests for the MSSM prediction. We also study the signals predicted for the non-SM-like Higgs bosons and emphasize the potential importance of the electroweak processes pp→H +H -, H ±A0, which are independent of the SUSY parameters except for their masses. In addition, there may be sizable contributions from pp→H ±h0, A0h0 and W ±H0, ZH0 in the low-mass non-decoupling region, which may serve to discriminate the model parameters. We allow variations of the relevant SUSY parameters in a broad range and demonstrate the correlations and constraints on these parameters and associated SUSY particles. © 2012 American Physical Society.
Neugebauer M.,University of Arizona
Space Science Reviews | Year: 2013
A survey of propagating interplanetary shocks reveals the following properties: (1) More shocks are observed around solar-activity maximum than minimum. (2) The maximum frequency of shock occurrence is between 2 and 5 AU. (3) Shocks slow down in the inner solar system, but in the outer solar system some may get a boost in speed when overtaken by a following shock. (4) The average shock strength (as measured by either the Mach number or the density ratio) also reaches peak values at distances of 2-5 AU. (5) Shocks are stronger at their noses than at their flanks. (6) At 1 AU, there are many more quasiperpendicular than quasiparallel shocks with the frequency of occurrence roughly constant with the cosine of the angle between the upstream field and the shock normal. © 2010 Springer Science+Business Media B.V.
Mantyh P.,University of Arizona
Pain | Year: 2013
Common cancers, including cancers of the breast, lung, and prostate, frequently metastasize to multiple bones where they can cause significant and life-altering pain. Similar to cancer itself, the factors that drive bone cancer pain evolve and change with disease progression. Once cancer cells have metastasized to bone, both the cancer cells and their associated stromal cells generate pain by releasing algogenic substances including protons, bradykinin, endothelins, prostaglandins, proteases, and tyrosine kinase activators. The release of these factors by cancer/stromal cells can induce sensitization and activation of nerve fibers that innervate the bone. Additionally, these factors can drive a remarkable increase in the number, size, and activity of bone-destroying osteoclasts, which can ultimately result in fracture of the tumor-bearing bone. Tumor growth in bone can also generate a neuropathic pain by directly injuring nerve fibers as well as inducing an active and highly pathological sprouting of both sensory and sympathetic nerve fibers that normally innervate the bone. This structural reorganization of sensory and sympathetic nerve fibers in the bone, combined with the cellular and neurochemical reorganization that occurs in the spinal cord and brain, appears to contribute to the peripheral and central sensitization that is common in advanced bone cancer pain. These mechanistic insights have begun to lead to advances in both how we understand and treat bone cancer pain. © 2012 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved.
Ellis B.J.,University of Arizona |
Del Giudice M.,University of New Mexico
Development and Psychopathology | Year: 2014
How do exposures to stress affect biobehavioral development and, through it, psychiatric and biomedical disorder? In the health sciences, the allostatic load model provides a widely accepted answer to this question: stress responses, while essential for survival, have negative long-term effects that promote illness. Thus, the benefits of mounting repeated biological responses to threat are traded off against costs to mental and physical health. The adaptive calibration model, an evolutionary-developmental theory of stress-health relations, extends this logic by conceptualizing these trade-offs as decision nodes in allocation of resources. Each decision node influences the next in a chain of resource allocations that become instantiated in the regulatory parameters of stress response systems. Over development, these parameters filter and embed information about key dimensions of environmental stress and support, mediating the organism's openness to environmental inputs, and function to regulate life history strategies to match those dimensions. Drawing on the adaptive calibration model, we propose that consideration of biological fitness trade-offs, as delineated by life history theory, is needed to more fully explain the complex relations between developmental exposures to stress, stress responsivity, behavioral strategies, and health. We conclude that the adaptive calibration model and allostatic load model are only partially complementary and, in some cases, support different approaches to intervention. In the long run, the field may be better served by a model informed by life history theory that addresses the adaptive role of stress response systems in regulating alternative developmental pathways. © 2014 Cambridge University Press.
Moskowitz G.B.,Lehigh University |
Stone J.,University of Arizona
American Journal of Public Health | Year: 2012
Objectives. We investigated whether stereotypes unconsciously influence the thinking and behavior of physicians, as they have been shown to do in other professional settings, such as among law enforcement personnel and teachers. Methods.We conducted 2 studies to examine whether stereotypes are implicitly activated in physicians. Study 1 assessed what diseases and treatments doctors associate with African Americans. Study 2 presented these (and control terms) to doctors as part of a computerized task. Subliminal images of African American and White men appeared prior to each word, and reaction times to words were recorded. Results. When primedwith an African American face, doctors reactedmore quickly for stereotypical diseases, indicating an implicit association of certain diseases with African Americans. These comprised not only diseases African Americans are genetically predisposed to, but also conditions and social behaviorswith no biological association (e.g., obesity, drug abuse). Conclusions. We found implicit stereotyping among physicians; faces they never consciously saw altered performance. This suggests that diagnoses and treatment of African American patients may be biased, even in the absence of the practitioner's intent or awareness.
Zhang L.,University of Arizona
Rock Mechanics and Rock Engineering | Year: 2010
Determination of the strength of jointed rock masses is an important and challenging task in rock mechanics and rock engineering. In this article, the existing empirical methods for estimating the unconfined compressive strength of jointed rock masses are reviewed and evaluated, including the jointing index methods, the joint factor methods, and the methods based on rock mass classification. The review shows that different empirical methods may produce very different estimates. Since in many cases, rock quality designation (RQD) is the only information available for describing rock discontinuities, a new empirical relation is developed for estimating rock mass strength based on RQD. The newly developed empirical relation is applied to estimate the unconfined compressive strength of rock masses at six sites and the results are compared with those from the empirical methods based on rock mass classification. The estimated unconfined compressive strength values from the new empirical relation are essentially in the middle of the estimated values from the different empirical methods based on rock mass classification. Similar to the existing empirical methods, the newly developed relation is only approximate and should be used, with care, only for a first estimate of the unconfined compressive strength of rock masses. Recommendations are provided on how to apply the newly developed relation in combination with the existing empirical methods for estimating rock mass strength in practice. © Springer-Verlag 2009.
Tokunaga R.S.,University of Arizona
Computers in Human Behavior | Year: 2010
More than 97% of youths in the United States are connected to the Internet in some way. An unintended outcome of the Internet's pervasive reach is the growing rate of harmful offenses against children and teens. Cyberbullying victimization is one such offense that has recently received a fair amount of attention. The present report synthesizes findings from quantitative research on cyberbullying victimization. An integrative definition for the term cyberbullying is provided, differences between traditional bullying and cyberbullying are explained, areas of convergence and divergence are offered, and sampling and/or methodological explanations for the inconsistencies in the literature are considered. About 20-40% of all youths have experienced cyberbullying at least once in their lives. Demographic variables such as age and gender do not appear to predict cyberbullying victimization. Evidence suggests that victimization is associated with serious psychosocial, affective, and academic problems. The report concludes by outlining several areas of concern in cyberbullying research and discusses ways that future research can remedy them. © 2009 Elsevier Ltd. All rights reserved.
Vercelli D.,University of Arizona
Allergology International | Year: 2016
Asthma and other allergic diseases are among the most prevalent chronic non-communicable diseases of childhood. According to the World Health Organization, asthma affects >7.0 million children under 18 in the United States, with an economic burden that is estimated to exceed that of tuberculosis and HIV/AIDS combined. Despite much research, the natural history of asthma and its pathogenesis are still in many ways elusive. This review discusses our current understanding of the role epigenetic processes play in asthma pathogenesis, focusing on genome-wide, population-based studies. © 2016 Japanese Society of Allergology.
Lin M.,University of Arizona |
Lucas H.C.,University of Maryland University College |
Shmueli G.,Srini Raju Center for and the Networked economics
Information Systems Research | Year: 2013
The Internet has provided IS researchers with the opportunity to conduct studies with extremely large samples, frequently well over 10,000 observations. There are many advantages to large samples, but researchers using statistical inference must be aware of the p-value problem associated with them. In very large samples, p-values go quickly to zero, and solely relying on p-values can lead the researcher to claim support for results of no practical significance. In a survey of large sample IS research, we found that a significant number of papers rely on a low p-value and the sign of a regression coefficient alone to support their hypotheses. This research commentary recommends a series of actions the researcher can take to mitigate the p-value problem in large samples and illustrates them with an example of over 300,000 camera sales on eBay. We believe that addressing the p-value problem will increase the credibility of large sample IS research as well as provide more insights for readers. © 2013, INFORMS.
Hameroff S.,University of Arizona |
Penrose R.,University of Oxford
Physics of Life Reviews | Year: 2014
The nature of consciousness, the mechanism by which it occurs in the brain, and its ultimate place in the universe are unknown. We proposed in the mid 1990's that consciousness depends on biologically 'orchestrated' coherent quantum processes in collections of microtubules within brain neurons, that these quantum processes correlate with, and regulate, neuronal synaptic and membrane activity, and that the continuous Schrödinger evolution of each such process terminates in accordance with the specific Diósi-Penrose (DP) scheme of 'objective reduction' ('OR') of the quantum state. This orchestrated OR activity ('Orch OR') is taken to result in moments of conscious awareness and/or choice. The DP form of OR is related to the fundamentals of quantum mechanics and space-time geometry, so Orch OR suggests that there is a connection between the brain's biomolecular processes and the basic structure of the universe. Here we review Orch OR in light of criticisms and developments in quantum biology, neuroscience, physics and cosmology. We also introduce a novel suggestion of 'beat frequencies' of faster microtubule vibrations as a possible source of the observed electro-encephalographic ('EEG') correlates of consciousness. We conclude that consciousness plays an intrinsic role in the universe. © 2013 Elsevier B.V.
Furfaro R.,University of Arizona
Journal of Guidance, Control, and Dynamics | Year: 2015
Close-proximity operations around small bodies in general and asteroids in particular are extremely challenging. In this paper, we apply the higher-order sliding modes theory to devise a class of discontinuous two-sliding homogeneous controllers for hovering in highly uncertain dynamical environments typically found around asteroids. The class of controllers that can be constructed using the higher-order sliding modes theory is shown to be globally finite-time stable against perturbations with a known upper bound. The behavior of the proposed two-sliding controller as a function of the design parameters has been analyzed via a set of closed-loop simulations around 433 Eros and 1999 RQ36 Bennu. For all cases, the controller is demonstrated to be highly effective in achieving and maintaining the hovering state in spite of perturbing accelerations as well as navigation errors. Moreover, it has been demonstrated that the two-sliding controller can be implemented in a bang-off-bang fashion for propellant saving while maintaining the desired performances (i.e., robustness and good accuracy). © 2014 by the American Institute of Aeronautics and Astronautics, Inc.
Marcus F.I.,University of Arizona |
Edson S.,ARVD Heart for Hope |
Towbin J.A.,Heart Institute
Journal of the American College of Cardiology | Year: 2013
Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a genetically transmitted disease. However, the genetics are more complex than in other inherited conditions wherein a single gene abnormal mutation may be causative. In ARVC, 5 causative desmosomal genes have been identified, but because only 30% to 50% of patients with ARVC have 1 of these gene abnormalities, it is assumed that there are other genes not yet identified. Frequently, patients with ARVC have >1 genetic defect in the same gene (compound heterozygosity) or in a second complementary gene (digenic heterozygosity). In addition, a family member may have an ARVC gene defect and have development of the disease or have no or minimal manifestations of the disease. Clinical genetic testing is commercially available. It is beneficial for first-degree family members of a person with ARVC to have genetic testing but only if there is a known genetic abnormality in the affected person. If the affected family member (proband) with ARVC does not have a genetic defect identified, then it will not be identified in the family member. Genetic counseling is strongly advised for family members of the proband. © 2013 American College of Cardiology Foundation.
Giacalone J.,University of Arizona
Space Science Reviews | Year: 2013
This paper reviews selected topics in cosmic-ray transport in the heliosphere, as well as recent insights on the interaction of cosmic rays with shocks. Topics include: (a) recent observations suggesting very long inferred scattering mean-free paths of cosmic rays, (b) recent insights into the diffusion of cosmic rays normal to a magnetic field, (c) the physics of super-diffusion and sub-diffusion, and (e) the interaction of cosmic rays with shocks moving through large-scale irregular magnetic fields. © 2011 Springer Science+Business Media B.V.
Peterson T.E.,Vanderbilt University |
Furenlid L.R.,University of Arizona
Physics in Medicine and Biology | Year: 2011
The development of radiation detectors capable of delivering spatial information about gamma-ray interactions was one of the key enabling technologies for nuclear medicine imaging and, eventually, single-photon emission computed tomography (SPECT). The continuous sodium iodide scintillator crystal coupled to an array of photomultiplier tubes, almost universally referred to as the Anger Camera after its inventor, has long been the dominant SPECT detector system. Nevertheless, many alternative materials and configurations have been investigated over the years. Technological advances as well as the emerging importance of specialized applications, such as cardiac and preclinical imaging, have spurred innovation such that alternatives to the Anger Camera are now part of commercial imaging systems. Increased computing power has made it practical to apply advanced signal processing and estimation schemes to make better use of the information contained in the detector signals. In this review we discuss the key performance properties of SPECT detectors and survey developments in both scintillator and semiconductor detectors and their readouts with an eye toward some of the practical issues at least in part responsible for the continuing prevalence of the Anger Camera in the clinic. © 2011 Institute of Physics and Engineering in Medicine.
McCutcheon J.P.,University of Arizona |
McCutcheon J.P.,University of Montana |
Von Dohlen C.D.,Utah State University
Current Biology | Year: 2011
Highly reduced genomes of 144-416 kilobases have been described from nutrient-provisioning bacterial symbionts of several insect lineages [1-5]. Some host insects have formed stable associations with pairs of bacterial symbionts that live in specialized cells and provide them with essential nutrients; genomic data from these systems have revealed remarkable levels of metabolic complementarity between the symbiont pairs [3, 4, 6, 7]. The mealybug Planococcus citri (Hemiptera: Pseudococcidae) contains dual bacterial symbionts existing with an unprecedented organization: an unnamed gammaproteobacteria, for which we propose the name Candidatus Moranella endobia, lives inside the betaproteobacteria Candidatus Tremblaya princeps . Here we describe the complete genomes and metabolic contributions of these unusual nested symbionts. We show that whereas there is little overlap in retained genes involved in nutrient production between symbionts, several essential amino acid pathways in the mealybug assemblage require a patchwork of interspersed gene products from Tremblaya, Moranella, and possibly P. citri. Furthermore, although Tremblaya has the smallest cellular genome yet described, it contains a genomic inversion present in both orientations in individual insects, starkly contrasting with the extreme structural stability typical of highly reduced bacterial genomes [4, 9, 10]. © 2011 Elsevier Ltd. All rights reserved.
Ayerza R.,University of Arizona
Industrial Crops and Products | Year: 2011
Moringa oleifera Lam. (M. pterygosperma Gaertn [Moringaceae]) is a fast-growing small tree native to the sub-Himalayan tracts of Northern India. The recognition that moringa oil has value in cosmetics has increased interest in cultivating it for seed-oil. The experimental trials were conducted in a semi-commercial moringa plantation in the subtropical northwestern region of Argentina, considering the similar climate conditions to the plant native region. Pods per tree, seeds per pod, weight of seed per pod, kernel weight, kernels oil content and fatty acid composition of PKM-1 and African cultivars were determined. One individual, E4-9, a PKM-1 plant, had significantly (P<0.05) higher production than all other plants. In addition, this individual was the highest extrapolated oil producer in both 2003 and 2004, with 595 and 564kgha-1, respectively (ave. 580kgha-1). Seed weight (200-seed wt.) was significantly greater in 2003 than 2004; no other traits studied showed significant differences between years. Both cultivars produced-oil with practically identical fatty acid composition, and the monounsaturated ω-9 oleic fatty acid accounted for more than 70% of the total for both cultivars. The polyunsaturated ω-6 linoleic fatty acid content of the African cultivar was slightly, but significantly (P<0.05), higher than that of PKM-1. © 2010 Elsevier B.V.
Sanchez-Soria P.,University of Arizona
Toxicologic pathology | Year: 2012
Cardiovascular disease is the leading cause of death in the United States and worldwide. High incidence of cardiovascular diseases has been linked to populations with elevated arsenic content in their drinking water. Although this correlation has been established in many epidemiological studies, a lack of experimental models to study mechanisms of arsenic-related cardiovascular pathogenesis has limited our understanding of how arsenic exposure predisposes for development of hypertension and increased cardiovascular mortality. Our studies show that mice chronically exposed to drinking water containing 100 parts per billion (ppb) sodium arsenite for 22 weeks show an increase in both systolic and diastolic blood pressure. Echocardiographic analyses as well as histological assessment show concentric left ventricular hypertrophy, a primary cardiac manifestation of chronic hypertension. Live imaging by echocardiography shows a 43% increase in left ventricular mass in arsenic-treated animals. Relative wall thickness (RWT) was calculated showing that all the arsenic-exposed animals show an RWT greater than 0.45, indicating concentric hypertrophy. Importantly, left ventricular hypertrophy, although often associated with chronic hypertension, is an independent risk factor for cardiovascular-related mortalities. These results suggest that chronic low-level arsenite exposure promotes the development of hypertension and the comorbidity of concentric hypertrophy.
Fraschetti F.,University of Arizona |
Fraschetti F.,University of Paris Descartes
Astrophysical Journal | Year: 2013
We analytically derive the vorticity generated downstream of a two-dimensional (2D) rippled hydromagnetic shock neglecting fluid viscosity and resistivity. The growth of the turbulent component of the downstream magnetic field is driven by the motion of vortical eddies. We determine an analytic time evolution of the magnetic field amplification at shocks, so far described only numerically, until saturation occurs due to seed-field reaction to the whirling of field lines. The explicit expression of the amplification growth rate and of the nonlinear field back-reaction in terms of the parameters of shock and interstellar density fluctuation is derived from MHD jump conditions at rippled shocks. A magnetic field saturation up to the order of milli-Gauss and a short-term variability in the X-ray observations of supernova remnants can be obtained by using reasonable parameters for the interstellar turbulence. © 2013. The American Astronomical Society. All rights reserved..
DeDe G.,University of Arizona
Aphasiology | Year: 2013
Background: Studies of sentence comprehension in non-disordered populations have convincingly demonstrated that probabilistic cues influence on-line syntactic processing. One well-studied cue is verb argument structure bias, which refers to the probability that a verb will occur in a particular syntactic frame. According to the Lexical Bias Hypothesis people with aphasia have difficulty understanding sentences in which the verb's argument structure bias conflicts with the sentence structure (e.g., a transitively biased verb in an intransitive sentence). This hypothesis may provide an account of why people with aphasia have difficulty understanding both simple and complex sentences.Aims: The purpose of this study was to test the Lexical Bias Hypothesis using an on-line measure of written sentence comprehension, self-paced reading. Methods & Procedures: The participants were 10 people with aphasia and 10 non-brain-damaged controls. The stimuli were syntactically simple transitive and intransitive sentences that contained transitively or intransitively biased verbs. For example, the transitively biased verb "called" appeared in sentences such as "The agent called (the writer) from overseas to make an offer." The intransitively biased verb "danced" appeared in sentences such as "The couple danced (the tango) every Friday night last summer."Outcomes & Results: Both groups' reading times for critical segments were longer when the verb's transitivity bias did not match the sentence structure, particularly in intransitive sentences.Conclusions: The results were generally consistent with the Lexical Bias Hypothesis, and demonstrated that lexical biases affect on-line processing of syntactically simple sentences in people with aphasia and controls. © 2013 Copyright Taylor and Francis Group, LLC.
Lanan M.,University of Arizona
Myrmecological News | Year: 2014
The distribution of food resources in space and time is likely to be an important factor governing the type of foraging strategy used by ants. However, no previous systematic attempt has been made to determine whether spatiotemporal resource distribution is in fact correlated with foraging strategy across the ants. In this analysis, I present data compiled from the literature on the foraging strategy and food resource use of 402 species of ants from across the phylogenetic tree. By categorizing the distribution of resources reported in these studies in terms of size relative to colony size, spatial distribution relative to colony foraging range, frequency of occurrence in time relative to worker life span, and depletability (i.e., whether the colony can cause a change in resource frequency), I demonstrate that different foraging strategies are indeed associated with specific spatiotemporal resource attributes. The general patterns I describe here can therefore be used as a framework to inform predictions in future studies of ant foraging behavior. No differences were found between resources collected via short-term recruitment strategies (group recruitment, short-term trails, and volatile recruitment), whereas different resource distributions were associated with solitary foraging, trunk trails, long-term trail networks, group raiding, and raiding. In many cases, ant species use a combination of different foraging strategies to collect diverse resources. It is useful to consider these foraging strategies not as separate options but as modular parts of the total foraging effort of a colony.
Karkoschka E.,University of Arizona
Icarus | Year: 2016
The altitude and zonal motion of the Huygens probe descending through Titan's atmosphere was determined early under the assumption of no meridional motion (Bird et al. . Nature 438, 800-802). By comparing images taken during the descent, Karkoschka et al. (Karkoschka et al. . Planet. Space Sci. 55, 1895-1935) determined the meridional motion of Huygens, which was generally much smaller than its zonal motion. Here, we present a comprehensive geometrical analysis of all images taken during the descent that is four times more accurate than the previous study. The result is a meridional wind profile across Titan's troposphere with northward winds by up to 0.4 m/s with an average of 0.1 m/s above 1 km altitude, and southward winds below, peaking at 0.9 m/s near 0.4 km altitude. The imaging data extend down to 0.22 km altitude, although additional information came from the horizontal impact speed near 0.8 m/s southward (Schröder et al. . Planet. Space Sci. 73, 327-340). There is a region between 5 and 8 km altitude with no significant meridional wind. In the stratosphere, the average meridional wind was 1.2 ± 1.5 m/s northward, and zero meridional motion is possible down to 15 km altitude. We present the difference between the zonal speeds of Huygens and the wind that was ignored in previous publications and amounts to up to 7 m/s. We determined the three rotational angles of Huygens for the times of each exposure that showed surface features. During 26 exposures, the swing speed of Huygens was fast enough to smear images. Inferred swing speeds were up to 20°/s during the calm phase of the descent, consistent with up to 40°/s swings reported before during the rough phase. The improved geometric calibration of images allowed identification of many features also seen in Cassini radar images. This comparison yields the location of the Huygens LandingSite as 192.34 ± 02° West and 10.47 ± 0.02° South. © 2015 Elsevier Inc.
Romero A.J.,University of Arizona
American Journal of Health Promotion | Year: 2012
Purpose. The primary purpose of the current study was to develop, implement, and evaluate a hip hop dance intervention, Latin Active, among low-income Mexican-American adolescents. Mexican-descent adolescents tend to have disproportionate rates of low physical activity, overweight status, and obesity. Design. A 5-week intervention design with pretest and post-test self-report measures. Setting. Charter middle school (grades 6-9) health/science classes in a low-income neighborhood were the setting for the Latin Active intervention. Participants. Overall, 81 participants were recruited; 73 (n 5 41, female; n 5 32, male) provided active parental consent to complete pretest/post-test surveys. Intervention. The Latin Active program included 10 interactive 50-minute lessons that were delivered twice a week during science/health classes. The curriculum was created on the basis of Social Cognitive Theory, Critical Hip Hop Pedagogy, and feedback from key stakeholders. The lessons focused on increasing physical activity as well as neighborhood barriers. Measures. The self-report pretest (n 5 73) and post-test (n 5 56) surveys included measures for frequency of vigorous physical activity, self-efficacy, and neighborhood barriers. Analysis. Paired-sample t-test analyses were conducted to assess mean differences from pretest to post-test results for intervention outcomes by gender. Results. The Latin Active program (with 77% retention at post-test) significantly increased vigorous physical activity and dance (p < .05) and increased self-efficacy (p < .05) among girls, and it decreased perception of neighborhood barriers (p < .05) among boys. Conclusion. A hip hop physical activity program, Latin Active demonstrated preliminary efficacy to increase girl's vigorous physical activity and boy's perception of neighborhood barriers to physical activity. Future research will need to use a randomized, controlled design and investigate the effect of the program on measures of body mass index. (Am J Health Promot 2012;26:208-211.) . © 2012 by American Journal of Health Promotion, Inc.
McGill B.J.,University of Arizona
Ecology Letters | Year: 2010
A unified theory in science is a theory that shows a common underlying set of rules that regulate processes previously thought to be distinct. Unified theories have been important in physics including the unification of electricity and magnetism and the unification of the electromagnetic with the weak nuclear force. Surprisingly, ecology, specifically the subfields of biodiversity and macroecology, also possess not one but at least six unified theories. This is problematic as only one unified theory is desirable. Superficially, the six unified theories seem very different. However, I show that all six theories use the same three rules or assertions to describe a stochastic geometry of biodiversity. The three rules are: (1) intraspecifically individuals are clumped together; (2) interspecifically global or regional abundance varies according to a hollow curve distribution; and (3) interspecifically individuals are placed without regard to individuals of other species. These three rules appear sufficient to explain local species abundance distributions, species-area relationships, decay of similarity of distance and possibly other patterns of biodiversity. This provides a unification of the unified theories. I explore implications of this unified theory for future research. © 2010 Blackwell Publishing Ltd/CNRS.
Eden S.,University of Arizona
Environmental Science and Policy | Year: 2011
This paper reports on an assessment of activities undertaken to accelerate the transfer of new science into water management decision making. Current trends in science policy emphasize the need for research to demonstrate tangible benefits for decision makers, at the same time resource management decisions are recognized as involving multiple scientific disciplines embedded in specific decision contexts. SAHRA, a U.S. National Science Foundation funded Science and Technology Center for Sustainability of semi-Arid Hydrology and Riparian Areas, has developed an innovative research framework intended to respond to these trends.Examination of the SAHRA experience yielded multiple lessons on research to support decision making, including strategies for reconciling needs for advances in science with providing decision support; fostering adoption of science products; and communicating with research users.These lessons reinforce basic principles of usable science described in the literature and expand evidence-based guidance on implementation, especially in building effective kn