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Arizona State University is a public metropolitan research university located on five campuses across the Phoenix, Arizona, Metropolitan Area. A sixth campus located in northwestern Arizona is known as the ASU Colleges at Lake Havasu City.ASU is the largest public university by enrollment in the United States. Founded in 1885 as the Territorial Normal School at Tempe, the school underwent a series of changes in name and curriculum. In 1945 it was placed under the direction of the Arizona Board of Regents and renamed Arizona State College. A 1958 statewide ballot measure gave the university its present name. ASU was classified as a Research I institute in 1994; thus, making it one of the newest major research universities in the nation.ASU is classified as a research university with very high research activity by the Carnegie Classification of Institutions of Higher Education. Since 2005 ASU has been ranked among the top research universities, public and private, in the U.S. based on research output, innovation, development, research expenditures, number of awarded patents and awarded research grant proposals. The Center for Measuring University Performance currently ranks ASU 31st among top U.S. public research universities.ASU's charter, approved by the board of regents in 2014, is based on the "New American University" model created by current ASU President Michael Crow. It defines ASU as “a comprehensive public research university, measured not by whom we exclude, but rather by whom we include and how they succeed; advancing research and discovery of public value; and assuming fundamental responsibility for the economic, social, cultural and overall health of the communities it serves.”ASU awards bachelor’s, master’s and doctoral degrees through 16 colleges and schools across all of its campuses: the original Tempe campus, the West campus in northwest Phoenix, the Polytechnic campus in eastern Mesa, the Downtown Phoenix campus, The Mayo Clinic/ASU Medical School in Scottsdale, and the Colleges at Lake Havasu City. ASU’s Online campus offers 41 undergraduate degrees, 37 graduate degrees and 14 graduate or undergraduate certificates which together have earned ASU a top 10 ranking for Best Online Programs.Students will compete in 24 varsity sports beginning in 2016. In conjunction with the transition of the men's ACHA club hockey team to Division I of the NCAA, the 24th varsity sport will be an NCAA women’s team: Rowing is among the favored possibilities. The Arizona State Sun Devils are members of the Pacific-12 Conference and have won 23 NCAA championships. Along with multiple athletic clubs and recreational facilities, ASU is home to more than 1,100 registered student organizations, reflecting the diversity of the student body. To keep pace with the growth of the student population, the university is continuously renovating and expanding infrastructure. The demand for new academic halls, athletic facilities, student recreation centers, and residential halls is being addressed with donor contributions and public-private investments. ASU's residential halls accommodate one of the largest residential populations in the nation. Wikipedia.


Murray A.T.,Arizona State University
Fire Safety Journal | Year: 2013

One of the most essential public services in urban areas is fire protection and response. It also happens to be one of the most costly. As urban areas grow, develop and change, it is important to plan services accordingly, both in terms of safety as well as being fiscally responsible. This paper discusses strategic planning goals and objectives in fire protection and response, and details modeling approaches to support fire station siting. A case study examining a fire service system for a city in California is used to illustrate the importance of strategic planning and system re-evaluation when expanding services. © 2013 Elsevier Ltd. All rights reserved.


Okie J.G.,Arizona State University | Okie J.G.,University of New Mexico
American Naturalist | Year: 2013

Surface areas and volumes of biological systems-from molecules to organelles, cells, and organisms-affect their biological rates and kinetics. Therefore, surface area-to-volume ratios and the scaling of surface area with volume profoundly influence ecology, physiology, and evolution. The zeroth-order geometric expectation is that surface area scales with body mass or volume as a power law with an exponent of two-thirds, with consequences for surface area- to-volume (SA: V) ratios and constraints on size; however, organisms have adaptations for altering the surface area scaling and SA: V ratios of their bodies and structures. The strategies fall into three groups: (1) fractal-like surface convolutions and crinkles; (2) classic geometric dissimilitude through elongating, flattening, fattening, and hollowing; and (3) internalization of surfaces. Here I develop general quantitative theory to model the spectra of effects of these strategies on SA: V ratios and surface area scaling, from exponents of less than two-thirds to superlinear scaling and mixed-power laws. Applying the theory to cells helps quantitatively evaluate the effects of membrane fractality, shape-shifting, vacuoles, vesicles, and mitochondria on surface area scaling, informing understanding of cell allometry, morphology, and evolution. Analysis of compiled data indicates that through hollowness and surface internalization, eukaryotic phytoplankton increase their effective surface area scaling, attaining near-linear scaling in larger cells. This unifying theory highlights the fundamental role of biological surfaces in metabolism and morphological evolution. © 2013 by The University of Chicago. 0003-0147/2013/18103-54025$15.00. All rights reserved.


Spence J.C.H.,Arizona State University
Faraday Discussions | Year: 2014

We describe several schemes for time-resolved imaging of molecular motion using a freeelectron laser (XFEL), in response to the many challenges and opportunities which XFEL radiation has created for accurate time-resolved measurement of structure. For pump- probe experiments using crystals, the problem of recording full Bragg reflections (not partials) in each shot arises. Two solutions, the use of the large bandwith which necesarily results from using attosecond pulses, and the use the coherent convergent beam mode are suggested. We also show that with attosecond recording times shorter than the temporal coherence time, Bragg reflections excited by different wavelengths from different reflections can interfere, providing structure factor phase information. For slower processes, a mixing jet sample-delivery device is described to allow snapshot solution scattering during molecular reactions on the microsecond scale. For optically excited membrane proteins, we suggest the use of the lipid cubic phase sample delivery device operating at atmospheric pressure. The use of two-color and split-and-delay schemes is suggested for improved accuracy in the Monte-Carlo method of serial femtosecond crystallography (SFX). © The Royal Society of Chemistry 2014.


Trovitch R.J.,Arizona State University
Synlett | Year: 2014

A brief review of manganese-catalyzed hydrosilylation is presented along with a personal account of how the design for the highly active catalyst, ( Ph2PPrPDI)Mn, was conceived. The reductive transformations achieved using this catalyst are described and put into further context by comparing the observed activities with those attained for leading late first-row transition-metal catalysts.


Collins J.P.,Arizona State University
Diseases of Aquatic Organisms | Year: 2010

For over 350 million yr, thousands of amphibian species have lived on Earth. Since the 1980s, amphibians have been disappearing at an alarming rate, in many cases quite suddenly. What is causing these declines and extinctions? In the modern era (post 1500) there are 6 leading causes of biodiversity loss in general, and all of these acting alone or together are responsible for modern amphibian declines: commercial use; introduced/exotic species that compete with, prey on, and parasitize native frogs and salamanders; land use change; contaminants; climate change; and infectious disease. The first 3 causes are historical in the sense that they have been operating for hundreds of years, although the rate of change due to each accelerated greatly after about the mid-20th century. Contaminants, climate change, and emerging infectious diseases are modern causes suspected of being responsible for the so-called 'enigmatic decline' of amphibians in protected areas. Introduced/exotic pathogens, land use change, and infctious disease are the 3 causes with a clear role in amphibian decline as well as extinction; thus far, the other 3 causes are only implicated in decline and not extinction. The present work is a review of the 6 causes with a focus on pathogens and suggested areas where new research is needed. Batrachochytrium dendrobatidis (Bd) is a chytrid fungus that is an emerging infectious disease causing amphibian population decline and species extinction. Historically, pathogens have not been seen as a major cause of extinction, but Bd is an exception, which is why it is such an interesting, important pathogen to understand. The late 20th and early 21st century global biodiversity loss is characterized as a sixth extinction event. Amphibians are a striking example of these losses as they disappear at a rate that greatly exceeds historical levels. Consequently, modern amphibian decline and extinction is a lens through which we can view the larger story of biodiversity loss and its consequences. © Inter-Research 2010.


Seeling P.,Central Michigan University | Reisslein M.,Arizona State University
IEEE Communications Surveys and Tutorials | Year: 2012

The performance evaluation of video transport mechanisms becomes increasingly important as encoded video accounts for growing portions of the network traffic. Compared to the widely studied MPEG-4 encoded video, the recently adopted H.264 video coding standards include novel mechanisms, such as hierarchical B frame prediction structures and highly efficient quality scalable coding, that have important implications for network transport. This tutorial introduces a trace-based evaluation methodology for the network transport of H.264 encoded video. We first give an overview of H.264 video coding, and then present the trace structures for capturing the characteristics of H.264 encoded video. We give an overview of the typical video traffic and quality characteristics of H.264 encoded video. Finally, we explain how to account for the H.264 specific coding mechanisms, such as hierarchical B frames, in networking studies. © 2012 IEEE.


Sumanasooriya M.S.,Clarkson University | Neithalath N.,Arizona State University
Cement and Concrete Composites | Year: 2011

The pore structure features such as the pore volume fractions, pore sizes, specific surface areas, and connectivity dictate the properties of any porous material. In this paper, an analysis of the pore structure features of pervious concretes designed for similar porosities using two different proportioning methods - one with higher paste contents and lower compactive efforts and another with lower paste contents and higher compactive efforts - is carried out. The porosities (both from volumetric and image analysis based methods) and characteristic pore sizes obtained from morphological functions are found to be statistically similar for the high-paste and low-paste content mixtures, while the low-paste content mixtures show a higher specific surface area of pores. The extracted pore structure features, when used in the Katz-Thompson equation for permeability prediction, result in over-estimation of permeability for specimens with larger pore sizes. A correction factor for the Katz-Thompson constant is found to be linearly related to the granulometry-based pore sizes. © 2011 Elsevier Ltd. All rights reserved.


Terzano K.,Arizona State University
Accident Analysis and Prevention | Year: 2013

As planners and public health officials in many cities around the world seek to increase bicycle ridership, bicyclists who are performing a secondary task (such as listening to a portable music device) may pose a risk to public safety. This study examines bicycling safety and potentially distracted behavior in The Hague, the Netherlands, a place where bicycling is a common, everyday travel mode among all walks of life and where bicycling infrastructure is well developed. Based on 1360 observations of bicycling behavior, this study shows that bicyclists who were using a cell phone, listening to a portable music device, or talking with other bicyclists exhibited more unsafe behaviors than those bicyclists who were not performing a secondary task. Furthermore, bicyclists who were performing a secondary task also more frequently created situations where other people had to evade them to avoid an accident. As with distracted car driving, the performance of a secondary task while bicycling may be unsafe for the person engaging in the behavior as well as for other people around them. © 2013 Elsevier Ltd. All rights reserved.


Bradley R.H.,Arizona State University | Putnick D.L.,Eunice Kennedy Shriver National Institute of Child Health and Human Development
Child Development | Year: 2012

This study examined home environment conditions (housing quality, material resources, formal and informal learning materials) and their relations with the Human Development Index (HDI) in 28 developing countries. Home environment conditions in these countries varied widely. The quality of housing and availability of material resources at home were consistently tied to HDI; the availability of formal and informal learning materials a little less so. Gross domestic product (GDP) tended to show a stronger independent relation with housing quality and material resources than life expectancy and education. Formal learning resources were independently related to the GDP and education indices, and informal learning resources were not independently related to any constituent indices of the overall HDI. © 2012 The Authors. Child Development © 2012 Society for Research in Child Development, Inc.


Kelman C.C.,Arizona State University
Conservation and Society | Year: 2013

Governance issues are at the heart of successful biodiversity conservation and sustainable development. This article examines two Integrated Conservation and Development Projects (ICDPs) conducted in parks on Sumatra, to better understand the foundations of effective biodiversity conservation programmes. The ICDP centred on a networked and multiscalar approach to governance issues seems to have had a longer-term positive impact on truly protecting biodiversity than the one that focused elsewhere. The findings from this research support the notion that an overarching spotlight on institutions and multilevel governance matters (ranging from spatial planning and policy making to arresting poachers to battling corruption) can help in addressing many conservation and development dilemmas. Grounded in field research, this paper calls for a model of biodiversity conservation based on multilayered, networked governance structures, proper law enforcement, and an emphasis on the development of institutional capacity, especially at the local level. These networks should be nurtured by long-term partnerships between governments, communities, and NGOs. Donors and planners should focus on these key areas in conservation design.


Herrmann M.,Arizona State University
Atomization and Sprays | Year: 2011

The atomization process of turbulent liquid jets is as of this day not well understood. Detailed numerical simulations can help study the fundamental mechanisms in regions where experimental access and analysis is difficult. This paper presents simulation results of the primary atomization of round turbulent liquid jets injected into stagnant highpressure air under diesel engine conditions using the refined level set grid approach. A balanced force approach is used to accurately account for surface tension forces using an interface projected curvature method to minimize erroneous spurious currents. Broken off, small-scale nearly spherical drops are transferred into a Lagrangian point particle description allowing for full two-way coupling. The physical mechanisms resulting in the initial breakup of the jet are discussed. We analyze the impact of finite grid resolution on the phase interface geometry of the injected liquid core and discuss the impact of the automatic topology-change length scale inherent in the fixed grid interface, capturing methods like the level set method. Drop size distributions resulting from primary atomization are presented, showing that grid-independent drop sizes can be achieved for liquid structures resolved by at least six grid points. © 2011 by Begell House, Inc.


Haas S.A.,Pennsylvania State University | Schaefer D.R.,Arizona State University
Journal of Health and Social Behavior | Year: 2014

This study investigates whether peer influence on smoking among adolescents is asymmetrical. We hypothesize that several features of smoking lead peers to have a stronger effect on smoking initiation than cessation. Using data from the National Longitudinal Study of Adolescent Health we estimate a dynamic network model that includes separate effects for increases versus decreases in smoking, while also controlling for endogenous network change. We find that the impact of peer influence is stronger for the initiation of smoking than smoking cessation. Adolescents rarely initiate smoking without peer influence but will cease smoking while their friends continue smoking. We discuss the implications of these results for theories of peer influence and health policy. © American Sociological Association 2014.


Jahnke R.,Arizona State University
American journal of health promotion : AJHP | Year: 2010

OBJECTIVE: Research examining psychological and physiological benefits of Qigong and Tai Chi is growing rapidly. The many practices described as Qigong or Tai Chi have similar theoretical roots, proposed mechanisms of action, and expected benefits. Research trials and reviews, however, treat them as separate targets of examination. This review examines the evidence for achieving outcomes from randomized controlled trials (RCTs) of both. DATA SOURCES: The key words Tai Chi, Taiji, Tai Chi Chuan, and Qigong were entered into electronic search engines for the Cumulative Index for Allied Health and Nursing (CINAHL), psychological literature (PsycINFO), PubMed, Cochrane database, and Google Scholar. STUDY INCLUSION CRITERIA: RCTs reporting on the results of Qigong or Tai Chi interventions and published in peer-reviewed journals from 1993 to 2007. DATA EXTRACTION: Country, type and duration of activity, number/type of subjects, control conditions, and reported outcomes were recorded for each study. SYNTHESIS: Outcomes related to Qigong and Tai Chi practice were identified and evaluated. RESULTS: Seventy-seven articles met the inclusion criteria. The nine outcome category groupings that emerged were bone density (n = 4), cardiopulmonary effects (n = 19), physical function (n = 16), falls and related risk factors (n = 23), quality of life (n = 17), self-efficacy (n = 8), patient-reported outcomes (n = 13), psychological symptoms (n = 27), and immune function (n = 6). CONCLUSIONS: Research has demonstrated consistent, significant results for a number of health benefits in RCTs, evidencing progress toward recognizing the similarity and equivalence of Qigong and Tai Chi.


Asphaug E.,Arizona State University
Annual Review of Earth and Planetary Sciences | Year: 2014

Earth formed in a series of giant impacts, and the last one made the Moon. This idea, an edifice of post-Apollo science, can explain the Moon's globally melted silicate composition, its lack of water and iron, and its anomalously large mass and angular momentum. But the theory is seriously called to question by increasingly detailed geochemical analysis of lunar rocks. Lunar samples should be easily distinguishable from Earth, because the Moon derives mostly from the impacting planet, in standard models of the theory. But lunar rocks are the same as Earth in O, Ti, Cr, W, K, and other species, to measurement precision. Some regard this as a repudiation of the theory; others say it wants a reformation. Ideas put forward to salvage or revise it are evaluated, alongside their relationships to past models and their implications for planet formation and Earth. © 2014 by Annual Reviews. All rights reserved.


Gu B.,Arizona State University | Ye Q.,Harbin Institute of Technology
Production and Operations Management | Year: 2014

With the growing influence of online social media, firms increasingly take an active role in interacting with consumers in social media. For many firms, their first step in online social media is management responses, where the management responds to customers' comments about the firm or its products and services. In this article, we measure the impact of management responses on customer satisfaction using data retrieved from a major online travel agency in China. Applying a panel data model that controls for regression toward the mean and heterogeneity in individual preference for hotels, we find that online management responses are highly effective among low satisfaction customers but have limited influence on other customers. Moreover, we show that the public nature of online management responses introduces a new dynamic among customers. Although online management responses increase future satisfaction of the complaining customers who receive the responses, they decrease future satisfaction of complaining customers who observe but do not receive management responses. The result is consistent with the peer-induced fairness theory. © 2013 Production and Operations Management Society.


Rey S.,Arizona State University
Journal of Geographical Systems | Year: 2014

Markov chains have become a mainstay in the literature on regional income distribution dynamics and convergence. Despite its growing popularity, the Markov framework has some restrictive characteristics associated with the underlying discretization income distributions. This paper introduces several new approaches designed to mitigate some of the issues arising from discretization. Based on the examination of rank distributions, two new Markov-based chains are developed. The first explores the movement of individual economies through the income rank distribution over time. The second provides insight on the movements of ranks over geographical space and time. These also serve as the foundation for two new tests of spatial dynamics or the extent to which movements in the rank distribution are spatially clustered. An illustration of these new methods is included using income data for the lower 48 US states for the years 1929-2009. © 2013 Springer-Verlag Berlin Heidelberg.


Chen X.,Arizona State University
International Journal of Quantum Chemistry | Year: 2013

We construct a hydrogen-bond based metal-molecule-metal junction, which contains two identical "reader" molecules, one single DNA base as a bridged molecule, and two titanium nitride electrodes. Hydrogen bonds are formed between "reader" molecules and DNA base, whereas titanium-sulfur bonds are formed between "reader" molecules and titanium nitride electrodes. We perform electronic structure calculations for both the bare bridged molecule and the full metal-molecule-metal system. The projected density of states shows that when the molecule is connected to the titanium nitride electrode, the energy levels of the bridged molecule are shifted, with an indirect effect on the hydrogen bonds. This is similar to the case for a gold electrode but with a more pronounced effect. We also calculate the current-voltage characteristics for the molecular junctions containing each DNA base. Results show that titanium nitride as an electrode can generate distinct conductance for each DNA base, providing an alternative electrode for DNA sequencing. © 2013 Wiley Periodicals, Inc.


Richert R.,Arizona State University
Physical Review Letters | Year: 2010

A Comment on the Letter by Helén Jansson, Rikard Bergman, and Jan Swenson, Phys. Rev. Lett.PRLTAO0031-9007 104, 017802 (2010)10.1103/PhysRevLett. 104.017802. The authors of the Letter offer a Reply. © 2010 The American Physical Society.


Richert R.,Arizona State University
Physical Review Letters | Year: 2010

Physical aging appears consistent with homogeneous models that are based upon a single "inner clock", but incompatible with the established heterogeneous nature of relaxation in glass-forming materials and the concomitant dispersion of aging rates. This work demonstrates that aging follows the conceptually simpler model of heterogeneous dynamics that differs from the homogeneous case in the rate at which equilibrium is approached. However, the very fast modes within the relaxation time dispersion age according to a common inner clock, because their fictive temperatures are slaved to macroscopic softening. Evidence is provided for such a transition to homogeneous aging as the frequency is increased into the excess wing. The results explain why aging of glasses appears homogeneous and consistent with time aging-time superposition in cases where observations are based on the high frequency behavior. © 2010 The American Physical Society.


Halden R.U.,Arizona State University | Halden R.U.,Johns Hopkins University
Annual Review of Public Health | Year: 2010

By 2010, the worldwide annual production of plastics will surpass 300 million tons. Plastics are indispensable materials in modern society, and many products manufactured from plastics are a boon to public health (e.g., disposable syringes, intravenous bags). However, plastics also pose health risks. Of principal concern are endocrine-disrupting properties, as triggered for example by bisphenol A and di-(2-ethylhexyl) phthalate (DEHP). Opinions on the safety of plastics vary widely, and despite more than five decades of research, scientific consensus on product safety is still elusive. This literature review summarizes information from more than 120 peer-reviewed publications on health effects of plastics and plasticizers in lab animals and humans. It examines problematic exposures of susceptible populations and also briefly summarizes adverse environmental impacts from plastic pollution. Ongoing efforts to steer human society toward resource conservation and sustainable consumption are discussed, including the concept of the 5 Rs-i.e., reduce, reuse, recycle, rethink, restrain-"for minimizing pre-and postnatal exposures to potentially harmful components of plastics. Copyright © 2010 by Annual Reviews. All rights reserved.


Chen X.,Arizona State University
Applied Physics Letters | Year: 2013

We construct a molecular junction comprising two identical "reader" molecules that are each linked on one end to a DNA single base via hydrogen bonds and on the other end to a palladium electrode. The structure of the junction is thus palladium-reader-base-reader-palladium. The palladium-reader contacts occur via Pd-S bonds. We calculated the electronic structure and conductance of the molecular junctions. Compared with the performance of molecular junctions with gold or titanium nitride electrodes, the current-voltage characteristics of the molecular junctions with palladium electrodes show higher sensitivity to the identity of the bridging DNA base, allowing the DNA bases to be distinguished more easily. Therefore, palladium is a superior electrode for molecular electronics and DNA sequencing. © 2013 AIP Publishing LLC.


An understanding of site taphonomy is crucial to stratigraphic and artifact/ecofact interpretation. Numerous geogenic, biogenic, and anthropogenic activities have the potential to move artifacts after deposition and distort the patterning once present in hominid discarded debris. Taphonomy at a Middle Stone Age cave (Pinnacle Point 13B) near Mossel Bay, South Africa is investigated here using artifact orientation data collected during excavation. Two angle measurements (bearing and plunge) were taken for all artifacts with a distinct long axis. The data are analyzed here using both graphical and statistical approaches, and a new graphical approach is presented. Using these measurements it is possible to distinguish between layers and areas of the site that are minimally disturbed and those that have been reworked to varying degrees. Data of this type are still not usually presented in publications of stone age sites. Given the complexities of the taphonomic history of these ancient sites, such data and analyses should become standard practice. © 2010 Elsevier Ltd.


Tucker C.L.,University of Wyoming | Bell J.,University of Wyoming | Pendall E.,University of Wyoming | Ogle K.,Arizona State University
Global Change Biology | Year: 2013

Enhanced soil respiration in response to global warming may substantially increase atmospheric CO2 concentrations above the anthropogenic contribution, depending on the mechanisms underlying the temperature sensitivity of soil respiration. Here, we compared short-term and seasonal responses of soil respiration to a shifting thermal environment and variable substrate availability via laboratory incubations. To analyze the data from incubations, we implemented a novel process-based model of soil respiration in a hierarchical Bayesian framework. Our process model combined a Michaelis-Menten-type equation of substrate availability and microbial biomass with an Arrhenius-type nonlinear temperature response function. We tested the competing hypotheses that apparent thermal acclimation of soil respiration can be explained by depletion of labile substrates in warmed soils, or that physiological acclimation reduces respiration rates. We demonstrated that short-term apparent acclimation can be induced by substrate depletion, but that decreasing microbial biomass carbon (MBC) is also important, and lower MBC at warmer temperatures is likely due to decreased carbon-use efficiency (CUE). Observed seasonal acclimation of soil respiration was associated with higher CUE and lower basal respiration for summer- vs. winter-collected soils. Whether the observed short-term decrease in CUE or the seasonal acclimation of CUE with increased temperatures dominates the response to long-term warming will have important consequences for soil organic carbon storage. © 2012 Blackwell Publishing Ltd.


Qiu Y.,Arizona State University
Environmental and Resource Economics | Year: 2014

It is widely recognized that the adoption of energy saving innovations can induce an increase in the usage of the corresponding technologies and thus can possibly increase energy consumption. Among other concerns is that uncertainties regarding the magnitude of this "rebound effect" can deter policy makers from promoting energy efficiency. This paper analyzes the rebound effects of the adoption of energy efficient technologies in commercial buildings. Based upon a structural model of technology adoption and subsequent energy demand at the building level, the empirical results are that energy efficiency can reduce electricity use by about 35 % and natural gas consumption by about 50 %. © 2013 Springer Science+Business Media Dordrecht.


Smith D.J.,Arizona State University
Micron | Year: 2012

The performance of the high-resolution electron microscope has continued to evolve, with recent developments in hardware attachments enabling aberration correction to be directly achieved for both probe-corrected and image-corrected microscope geometries. Sub-Ångstrom resolution, once regarded as an unattainable dream, can nowadays be readily achieved with instruments that are being widely sold commercially. These instrumentation developments have played a central role in facilitating transformational advances in imaging (and analytical) capability, bringing both novel opportunities and fresh challenges for the electron microscopy community. This paper provides a short update of recent progress in atomic-resolution TEM and STEM imaging, and briefly discusses some of the associated issues and problems attracting close attention. © 2011 Elsevier Ltd.


Hodges K.V.,Arizona State University
Annual Review of Earth and Planetary Sciences | Year: 2016

Mature orogenic systems built by continent-continent collision feature orogenic plateaus flanked by accretionary wedges. Thermal-mechanical models of these systems predict the development of a thermally weakened orogenic infrastructure that is capable of lateral flow toward the orogenic foreland. Such flow, if it occurs, strongly influences the evolutionary pathway of a wedge. Although the architecture of a wedge features numerous large-displacement faults, three are preeminent in mature orogens: one that marks the base of the wedge and two others that mark the base and top, respectively, of the weakened infrastructure. These structures represent major decoupling horizons separating domains with distinctive deformational and thermal histories. Reviews of the geology of orogenic wedges in two mature orogenic systems-the Cenozoic Himalaya and the Paleozoic East Greenland Caledonides-show how this simple conceptual model provides a valuable context for studies of how collisional orogenic systems develop and how they interact with the surrounding lithosphere. Copyright © 2016 by Annual Reviews. All rights reserved.


The present study tested the relationships between macro-level violence and birthweight in structurally disadvantaged communities in the District of Columbia. The study hypothesized that both rates of violence and violence "uncertainty" (the latter was operationalized as within-census tract residual change scores in violence), should be inversely associated with birthweight among all live singleton births in DC from 2000 to 2002. Using mixed models, the study found that (1) patterns of violence and violence uncertainty were significantly associated with birthweight among mothers residing in structurally disadvantaged communities, and (2) these findings held for Black and Hispanic, but not white, mothers. The study argues that urban ecological researchers should begin to consider not just how rates (or levels) of violence influence health and other social outcomes in communities, but also the effects of violence uncertainty as a source of unpredictable risk and territorial disruption. © 2011 Elsevier Ltd.


Sallquist J.,Arizona State University
Emotion (Washington, D.C.) | Year: 2012

The relations between young children's mutual (reciprocated) and overall positive emotion (PE) with same- and other-gender peers and their social adjustment were explored. Children's PE and peers' PE were observed across the preschool year during peer interactions (N = 166; 46% girls; M age = 52 months). Results revealed that girls and boys had similar frequencies of overall PE and mutual PE when interacting with same-gender peers, but girls were marginally higher compared with boys in overall and mutual PE when interacting with other-gender peers. Girls and boys did not have greater rates of either type of PE after controlling for gender segregation during same- or other-gender interactions. Using structural equation modeling, children's mutual PE, regardless of their gender, positively predicted indicators of positive adjustment (e.g., prosocial behavior, cooperation) and negatively predicted indicators of negative adjustment (e.g., hyperactivity, disruption, exclusion by peers). Children's overall PE did not predict either type of adjustment. Findings support the importance of mutual PE for children's development. (PsycINFO Database Record (c) 2012 APA, all rights reserved).


Anselin L.,Arizona State University
International Regional Science Review | Year: 2012

This essay assesses the evolution of the way in which spatial data analytical methods have been incorporated into software tools over the past two decades. It is part retrospective and prospective, going beyond a historical review to outline some ideas about important factors that drove the software development, such as methodological advances, the open source movement and the advent of the Internet and cyberinfrastructure. The review highlights activities carried out by the author and his collaborators and uses SpaceStat, GeoDa, PySAL, and recent spatial analytical web services developed at the ASU GeoDa Center as illustrative examples. It outlines a vision for a spatial econometrics workbench as an example of the incorporation of spatial analytical functionality in a cyberGIS. © SAGE Publications 2012.


Mustard J.A.,Arizona State University
Cellular and Molecular Life Sciences | Year: 2014

A number of recent studies from as diverse fields as plant-pollinator interactions, analyses of caffeine as an environmental pollutant, and the ability of caffeine to provide protection against neurodegenerative diseases have generated interest in understanding the actions of caffeine in invertebrates. This review summarizes what is currently known about the effects of caffeine on behavior and its molecular mechanisms in invertebrates. Caffeine appears to have similar effects on locomotion and sleep in both invertebrates and mammals. Furthermore, as in mammals, caffeine appears to have complex effects on learning and memory. However, the underlying mechanisms for these effects may differ between invertebrates and vertebrates. While caffeine's ability to cause release of intracellular calcium stores via ryanodine receptors and its actions as a phosphodiesterase inhibitor have been clearly established in invertebrates, its ability to interact with invertebrate adenosine receptors remains an important open question. Initial studies in insects and mollusks suggest an interaction between caffeine and the dopamine signaling pathway; more work needs to be done to understand the mechanisms by which caffeine influences signaling via biogenic amines. As of yet, little is known about whether other actions of caffeine in vertebrates, such as its effects on GABAA and glycine receptors, are conserved. Furthermore, the pharmacokinetics of caffeine remains to be elucidated. Overall behavioral responses to caffeine appear to be conserved amongst organisms; however, we are just beginning to understand the mechanisms underlying its effects across animal phyla. © 2013 Springer.


Huberty J.L.,Arizona State University
Journal of physical activity & health | Year: 2013

Children's achievement of recommendations for moderate-to-vigorous physical activity (MVPA) in afterschool programs (ASP) is complex. It is unclear what elements of the ASP environment influence children's physical activity (PA). The purpose of this study was to determine the relationship of staff behaviors and ASP features (eg, organized activity, recreational equipment) to MVPA participation in youth attending ASPs. Data were collected in 12 ASPs in the Midwest. Staff behavior and child PA was measured using the System for Observing Play and Leisure Activity in Youth. The percentage of children's MVPA was examined in relation to staff behaviors and ASP features. Increases in MVPA were observed when staff were directly engaged in PA, verbally promoted MVPA, and when PA was organized and equipment was present. When 3 or more of these characteristics were present, the proportion of children engaged in MVPA increased by 25%-30%. Conversely, MVPA levels decreased when these characteristics were absent and when staff were attending to other ASP duties or were supervising. This study provides evidence about the specific staff behaviors that may influence higher proportions of youth being active during ASP and implies specific skills that need to be incorporated into ASP staff training.


There is growing evidence that psychiatric disorders maintain hierarchical associations where general and domain-specific factors play prominent roles (see D. Watson, 2005). Standard, unidimensional measurement models can fail to capture the meaningful nuances of such complex latent variable structures. The present study examined the ability of the multidimensional item response theory bifactor model (see R. D. Gibbons & D. R. Hedeker, 1992) to improve construct validity by serving as a bridge between measurement and clinical theories. Archival data consisting of 688 outpatients' psychiatric diagnoses and item-level responses to the Brief Symptom Inventory (BSI; L. R. Derogatis, 1993) were extracted from files at a university mental health clinic. The bifactor model demonstrated superior fit for the internal structure of the BSI and improved overall diagnostic accuracy in the sample (73%) compared with unidimensional (61%) and oblique simple structure (65%) models. Consistent with clinical theory, multiple sources of item variance were drawn from individual test items. Test developers and clinical researchers are encouraged to consider model-based measurement in the assessment of psychiatric distress. © 2011 American Psychological Association.


Harrison J.F.,Arizona State University | Haddad G.G.,University of California at San Diego
Annual Review of Physiology | Year: 2011

Drosophila melanogaster is a model genetic organism with an exceptional hypoxia tolerance relative to mammals. Forward genetic, microarray, and P-element manipulations and selection experiments have revealed multiple mechanisms of severe hypoxia tolerance, including RNA editing, downregulation of metabolism, and prevention of protein unfolding. Drosophila live in microbe-rich, semiliquid food in which hypoxia likely indicates deteriorating environments. Hypoxia reduces growth and size by multiple mechanisms, influencing larval feeding rates, protein synthesis, imaginal cell size, and control of molting. In moderate hypoxia, these effects appear to occur without ATP limitation and are instead mediated by signaling systems, including hypoxia-inducible factor and atypical guanyl cyclase sensing of oxygen, with downstream actions on behavior, anabolism, and the cell cycle. In hypoxia, flies develop smaller sizes, but size does not evolve, whereas in hyperoxia, flies evolve larger sizes without exhibiting developmental size plasticity, suggesting differential evolutionary responses to natural versus novel directions of oxygen change. © 2011 by Annual Reviews. All rights reserved.


Niu H.,Lanzhou Jiaotong University | Zhou X.,Arizona State University
Transportation Research Part C: Emerging Technologies | Year: 2013

This article focuses on optimizing a passenger train timetable in a heavily congested urban rail corridor. When peak-hour demand temporally exceeds the maximum loading capacity of a train, passengers may not be able to board the next arrival train, and they may be forced to wait in queues for the following trains. A binary integer programming model incorporated with passenger loading and departure events is constructed to provide a theoretic description for the problem under consideration. Based on time-dependent, origin-to-destination trip records from an automatic fare collection system, a nonlinear optimization model is developed to solve the problem on practically sized corridors, subject to the available train-unit fleet. The latest arrival time of boarded passengers is introduced to analytically calculate effective passenger loading time periods and the resulting time-dependent waiting times under dynamic demand conditions. A by-product of the model is the passenger assignment with strict capacity constraints under oversaturated conditions. Using cumulative input-output diagrams, we present a local improvement algorithm to find optimal timetables for individual station cases. A genetic algorithm is developed to solve the multi-station problem through a special binary coding method that indicates a train departure or cancellation at every possible time point. The effectiveness of the proposed model and algorithm are evaluated using a real-world data set. © 2013 Elsevier Ltd.


Chen X.,Arizona State University | Huang J.,Chinese University of Hong Kong
IEEE Journal on Selected Areas in Communications | Year: 2013

According to FCC's ruling for white-space spectrum access, white-space devices are required to query a database to determine the spectrum availability. In this paper, we study the database-assisted distributed white-space access point (AP) network design. We first model the cooperative and non-cooperative channel selection problems among the APs as the system-wide throughput optimization and non-cooperative AP channel selection games, respectively, and design distributed AP channel selection algorithms that achieve system optimal point and Nash equilibrium, respectively. We then propose a state-based game formulation for the distributed AP association problem of the secondary users by taking the cost of mobility into account. We show that the state-based distributed AP association game has the finite improvement property, and design a distributed AP association algorithm that can converge to a state-based Nash equilibrium. Numerical results show that the algorithm is robust to the perturbation by secondary users' dynamical leaving and entering the system. © 1983-2012 IEEE.


Hedrick P.W.,Arizona State University
Malaria Journal | Year: 2012

Malaria is one of the leading causes of death worldwide and has been suggested as the most potent type of selection in humans in recent millennia. As a result, genes involved in malaria resistance are excellent examples of recent, strong selection. In 1949, Haldane initially suggested that infectious disease could be a strong selective force in human populations. Evidence for the strong selective effect of malaria resistance includes the high frequency of a number of detrimental genetic diseases caused by the pleiotropic effects of these malaria resistance variants, many of which are loss of function mutants. Evidence that this selection is recent comes from the genetic dating of the age of a number of these malaria resistant alleles to less than 5,000 years before the present, generally much more recent than other human genetic variants. An approach to estimate selection coefficients from contemporary case-control data is presented. In the situations described here, selection is much greater than 1%, significantly higher than generally observed for other human genetic variation. With these selection coefficients, predictions are generated about the joint change of alleles S and C at the β-globin locus, and for α-thalassaemia haplotypes and S, variants that are unlinked but exhibit epistasis. Population genetics can be used to determine the amount and pattern of selection in the past and predict selection in the future for other malaria resistance variants as they are discovered. © 2012 Hedrick.


Baran S.E.,Arizona State University
Learning & memory (Cold Spring Harbor, N.Y.) | Year: 2010

Electrolytic lesions of the medial prefrontal cortex (PFCX) were examined using fear conditioning to assess the recall of fear extinction and performance in the Y-maze, open field, and object location/recognition in male and female Sprague-Dawley rats. Rats were conditioned to seven tone/footshocks, followed by extinction after 1-h and 24-h delays, revealing PFCX effects and sex differences during all phases of fear conditioning. In male rats, PFCX impaired 24-h recall of fear extinction to tone, which required the 1-h delay extinction and was not attributed to nonassociative factors. In contrast, sham and PFCX females increased freezing to tone following a 24-h delay, whether or not 1-h delay tone extinction was presented. Moreover, PFCX females failed to extinguish to tone, contrasting to the robust extinction to tone that was observed for sham females, PFCX, and sham males. Also, sex differences were found during acquisition, with sham females acquiring fear conditioning slower than PFCX females. By the last tone-shock presentation, sham and PFCX females showed a slight but significant reduction in freezing to tone relative to those of sham and PFCX males. Of the other behavioral measures, PFCX females maintained exploration of a novel object during object recognition when sham females habituated. PFCX did not influence other behaviors in the remaining tasks. These findings show important sex differences in PFC function, with the PFC influencing the recall of fear extinction in males and contributing to the acquisition and maintenance of fear extinction memory in females, perhaps through altering perseveration.


Gentili M.,University of Salerno | Mirchandani P.B.,Arizona State University
Transportation Research Part C: Emerging Technologies | Year: 2012

The problem of optimally locating sensors on a traffic network to measure flows has been object of growing interest in the past few years, due to its relevance in transportation systems. Different locations of sensors on the network can allow, indeed, the collection of data whose usage can be useful for traffic management and control purposes. Many different models have been proposed in the literature as well as corresponding solution approaches. The proposed existing models differ according to different criteria: (i) sensor types to be located on the network (e.g., counting sensors, image sensors, Automatic Vehicle Identification (AVI) readers), (ii) available a-priori information, and (iii) flows of interest (e.g., OD flows, route flows, link flows). The purpose of this paper is to review the existing contributions and to give a unifying picture of these models by categorizing them into two main problems: the Sensor Location Flow-Observability Problem and the Sensor Location Flow-Estimation Problem. For both the problems, we will describe the corresponding computational complexity and the existing results. After describing various models and identifying their advantages and limitations, we conclude with several promising directions for future research and discuss other classes of location problems that address different objectives than the ones reviewed in the paper. © 2012 Elsevier Ltd.


Oke A.,Arizona State University
International Journal of Production Economics | Year: 2013

In the past few decades, the concept of manufacturing flexibility has become a key competitive criterion for many manufacturing organizations. The importance of flexibility in supporting other competitive criteria such as cost, quality and delivery speed has also been recognized (Bolwijn and Kumpe, 1990). However, there is a dearth of studies linking flexibility with another competitive criterion - innovation. In this study, we investigate the influence of the interaction of mix flexibility and labor flexibility on product innovation based on a survey of UK manufacturing plants. Further, we investigate the role of climate for innovation both as an antecedent of product innovation and a moderator that moderates the influence of the interaction of mix flexibility and labor flexibility on product innovation. The analyses reveal that the interaction of mix flexibility and labor flexibility positively predicts product innovation in manufacturing plants. Climate for innovation positively predicts product innovation and also positively moderates the interaction of mix and labor flexibility on product innovation. The implications for theory and practice are discussed. © 2012 Elsevier B.V. All rights reserved.


There are numerous examples demonstrating that selection has greatly influenced phenotypes in wild-harvested species. Here, a significant reduction in horn size in trophy desert bighorn sheep rams over 30 years in a reintroduced population in Aravaipa Canyon, Arizona is documented. After examining the potential effects of a detrimental change in the environment, inbreeding depression, and hunter-caused evolutionary change, it appears that environmental deterioration, apparently from the effects of drought, may be a major cause of the decline in horn size. In particular, the reduction in ram horn size is positively associated with reduced winter lifetime rainfall over the 3 decades. Over the same period, the demographic indicator lamb-to-ewe ratio has also declined in the Aravaipa population. On the other hand, lamb-to-ewe ratio has not declined statewide in Arizona, and the population size in Aravaipa appears to be increasing, suggesting local- and trait-specific effects. Using a theoretical context, neither inbreeding depression nor hunter selection by themselves appear to the sole causes of the lower horn size. However, some combination of environmental factors, inbreeding depression, and hunter selection may have caused the decrease in observed horn size. It is not clear what management actions might be successful in countering the environmental effects on horn size, but supplemental feeding and cattle removal are suggested while translocation is suggested to counter the effects of inbreeding depression and reduced hunting and translocation are suggested to counter the effects of hunter selection. © 2011 The American Genetic Association. All rights reserved.


Villena V.H.,IE Business School | Revilla E.,IE Business School | Choi T.Y.,Arizona State University
Journal of Operations Management | Year: 2011

The literature on supply chain management (SCM) has consistently promoted the "bright side" of collaborative buyer-supplier relationships (BSRs). Based on the social capital argument, SCM scholars have investigated how a buyer can gain access to and leverage resources through its collaborative BSRs. Our study extends this research stream by considering the "dark side" of social capital in BSRs. It evaluates how social capital in its cognitive, relational, and structural forms contributes to or impedes value creation within BSRs. Both primary survey measures and secondary objective measures have been used in data analysis. The results show the presence of both the bright side, confirming the existing literature, and the dark side, extending the literature. There is an inverted curvilinear relationship between social capital and performance: Either too little or too much social capital can hurt performance. This study confirms that building social capital in a collaborative BSR positively affects buyer performance, but that if taken to an extreme it can reduce the buyer's ability to be objective and make effective decisions as well as increase the supplier's opportunistic behavior. Our study also examines how a buyer can delay the emergence of the dark side. It opens up new research avenues in the collaborative BSR context and suggests directions for future research and practice. © 2010 Elsevier B.V.


Kline M.A.,Arizona State University
Behavioral and Brain Sciences | Year: 2015

The human species is more reliant on cultural adaptation than any other species, but it is unclear how observational learning can give rise to the faithful transmission of cultural adaptations. One possibility is that teaching facilitates accurate social transmission by narrowing the range of inferences that learners make. However, there is wide disagreement about how to define teaching, and how to interpret the empirical evidence for teaching across cultures and species. In this article I argue that disputes about the nature and prevalence of teaching across human societies and nonhuman animals are based on a number of deep-rooted theoretical differences between fields, as well as on important differences in how teaching is defined. To reconcile these disparate bodies of research, I review the three major approaches to the study of teaching - mentalistic, culture-based, and functionalist - and outline the research questions about teaching that each addresses. I then argue for a new, integrated framework that differentiates between teaching types according to the specific adaptive problems that each type solves, and apply this framework to restructure current empirical evidence on teaching in humans and nonhuman animals. This integrative framework generates novel insights, with broad implications for the study of the evolution of teaching, including the roles of cognitive constraints and cooperative dilemmas in how and when teaching evolves. Finally, I propose an explanation for why some types of teaching are uniquely human, and discuss new directions for research motivated by this framework. Copyright © Cambridge University Press 2015.


Richert R.,Arizona State University
Annual Review of Physical Chemistry | Year: 2011

Near their glass transition temperature Tg, supercooled liquids display dramatic changes regarding the dynamics if subject to geometrical restrictions on the scale of 2 to 200 nm. Confinement-induced shifts of Tg of 25 K have been reported, equivalent to relaxation times that differ by several orders of magnitude compared with the bulk liquid at the same temperature. Both acceleration and frustration of structural relaxations have been observed, and the effects can depend strongly on the physical and chemical properties of the interface, on soft versus hard confinement, and on the size and dimensionality of the confining topology. This review attempts to extract a unifying picture from the past 20 years of diverse observations that involve experiments, simulations, and model considerations. © 2011 by Annual Reviews. All rights reserved.


Spence J.C.H.,Arizona State University
Acta Crystallographica Section A: Foundations of Crystallography | Year: 2013

We trace the historical development of W. L. Braggs law and the key experimental observation which made it possible using polychromatic radiation at a time when neither X-ray wavelengths nor cell constants were known. This led, through his phasing and solving large mineral structures (without use of a computer), to work on metals, proteins, bubble rafts and his X-ray microscope. The relationship of this to early X-ray microdiffraction is outlined, followed by a brief review of electron microdiffraction methods, where electron-probe sizes smaller than one unit cell can be formed with an interesting failure of Braggs law. We end with a review of recent femtosecond X-ray snapshot diffraction from protein nanocrystals, using an X-ray laser which generates pulses so short that they terminate before radiation damage can commence, yet subsequently destroy the sample. In this way, using short pulses instead of freezing, the nexus between dose, resolution and crystal size has been broken, opening the way to time-resolved diffraction without damage for a stream of identical particles.


Yager E.M.,University of Idaho | Schmeeckle M.W.,Arizona State University
Journal of Geophysical Research: Earth Surface | Year: 2013

Vegetation is ubiquitous in river channels and floodplains and alters mean flow conditions and turbulence. However, the effects of vegetation patches on near-bed turbulence, bed load transport rates, and sedimentation are not well understood. To elucidate the influence of emergent vegetation on local and patch-averaged bed load transport, we conducted a set of experiments in which we varied the mean flow velocity (U), total boundary shear stress (τ), or vegetation density between runs. We measured 2D velocity fields using Particle Imaging Velocimetry and bed load fluxes using high-speed video. Simulated rigid vegetation caused bed load fluxes to vary spatially by an order of magnitude, causing distinct scour zones adjacent to, and depositional bed forms between stems. These local patterns of sedimentation could impact recruitment and survival of other plants. Large bed load fluxes were collocated with high near-bed turbulence intensities that were three to four times larger than spatially averaged values. Higher vegetation densities increased the importance of inward and outward interactions, particularly downstream of vegetation. At the patch scale, greater stem densities caused either an increase or decrease in run-averaged bed load fluxes, depending on whether U or τ was held constant between runs. This implies that sedimentation in vegetation patches is not only a function of bed grain size, sediment supply, and vegetation density and species, but whether vegetation significantly impacts mean and local flow properties, which could depend on vegetation location. Commonly used bed load transport equations did not accurately predict average sediment fluxes in our experiments unless they accounted for the spatial variability in the near-bed Reynolds stress. ©2013. American Geophysical Union. All Rights Reserved.


VanLehn K.,Arizona State University
Interactive Learning Environments | Year: 2013

Modeling is becoming increasingly important both as a way to learn science and mathematics, and as a useful cognitive skill. Although many learning activities qualify as "modeling", this article focuses on activities where (1) students construct a model rather than explore a given model, (2) the model is expressed in a formal language rather than drawings, physical objects or natural language texts and (3) the model's predictions are generated by executing it on a computer. Most research on such learning activities has focused on getting students to successfully construct models, which they find very difficult to do. In the hope that new research can find ways to remove this bottleneck, this article attempts to list all the major ideas that have appeared in the literature and might be useful to those developing new learning activities involving model construction. The ideas are organized into a design space with five dimensions: (1) modeling language types, (2) ways for describing the systems that students should model, (3) instructional objectives and their corresponding assessments, (4) common student difficulties and (5) types of scaffolding. © 2013 Copyright Taylor and Francis Group, LLC.


Talen E.,Arizona State University
Urban Studies | Year: 2010

Depending on how diversity is defined, every city has at least some neighbourhoods that are diverse, despite the enduring reality that American cities tend to be highly segregated. This paper investigates six socially diverse neighbourhoods in Chicago from the perspective of the residents who live there. The specific focus is on the interaction between residents and physical form, spatial pattern, and the location and function of civic institutions. Six neighbourhoods in Cook County were selected that are simultaneously diverse along four dimensions: age, income, family type and race/ethnicity. From February to June 2006, tape-recorded interviews were conducted of 85 residents in the six neighbourhoods identified as being highly diverse on multiple dimensions. Residents were surveyed about their familiarity with, and opinions about, social diversity, in addition to questions designed to probe their feelings about the importance of place and neighbourhood context. © 2009 Urban Studies Journal Limited.


Cahill T.M.,Arizona State University
Environmental Science and Technology | Year: 2010

Size-resolved aerosol samples, including the entire ultrafine fraction, were simultaneously collected along a transect in California's Central Valley during the winter of 2009. The samples were analyzed for PAHs, alkanes, organic acids, and sugars. The results showed that the organic constituents of aerosols did not follow the same pattern as PM10, thus indicating that simple PM measurements are not good indicators of trace toxic organic chemicals. Levoglucosan, a tracer of wood smoke, was the most abundant organic chemical detected, thus demonstrating the predominance of wood smoke in the valley. The size profile of levoglucosan showed a maximum in the 0.34-0.56 μm size mode, which is larger than published emission profiles. This suggests that wood smoke aerosols increased in size as they aged in the environment Some chemicals, such as benzo[a]pyrene, had similar aerosol size profiles as levoglucosan and likely arose from the same source. Other chemicals, such as coronene and sugars, had very different size profiles, indicating that they have different sources. One unexpected result was the relatively large fraction of certain chemicals present in the ultrafine fraction, which highlights the importance of collecting the entire ultrafine fraction. © 2010 American Chemical Society.


Aktipis C.A.,University of California at San Francisco | Aktipis C.A.,Arizona State University | Boddy A.M.,University of California at San Francisco | Gatenby R.A.,H. Lee Moffitt Cancer Center and Research Institute | And 2 more authors.
Nature Reviews Cancer | Year: 2013

Somatic evolution during cancer progression and therapy results in tumour cells that show a wide range of phenotypes, which include rapid proliferation and quiescence. Evolutionary life history theory may help us to understand the diversity of these phenotypes. Fast life history organisms reproduce rapidly, whereas those with slow life histories show less fecundity and invest more resources in survival. Life history theory also provides an evolutionary framework for phenotypic plasticity, which has potential implications for understanding 'cancer stem cells'. Life history theory suggests that different therapy dosing schedules might select for fast or slow life history cell phenotypes, with important clinical consequences. © 2013 Macmillan Publishers Limited. All rights reserved.


Matyushov D.V.,Arizona State University
Journal of Physical Chemistry B | Year: 2011

We report numerical simulations of three hydrated heme proteins, myoglobin, cytochrome c, and cytochrome B562. The properties of interest are the dynamics and statistics of the electric field and electrostatic potential at hemes iron, as well as their separation into the protein and water components. We find that the electric field produced by both the protein and the hydration water relaxes on the time scale of 3-6 ns, and the relaxation time of the electrostatic potential is close to 1 ns. The slow dynamics of the electrostatic observables is accompanied by their large variances. For the electrostatic potential, a large amplitude of its fluctuations leads to a gigantic reorganization energy of a half redox reaction changing the redox state of the protein. Both a large magnitude and a slow relaxation time of the electric field fluctuations are required to explain the onset of large mean-square displacements of iron at the point of proteins dynamical transition. These requirements are met by the simulations which are used to explain the temperature dependence of heme iron displacements measured by Mössbauer spectroscopy. All three phenomena, (i) nanosecond dynamics, (ii) protein dynamical transition and a large high-temperature excess of atomic mean-square displacements, and (iii) the gigantic reorganization energy, are explained here by one physical mechanism. This mechanism involves two components: nanosecond motions of the protein surface residues and polarization of the interfacial water by the protein charges. Global nanosecond conformations of the protein move the surface water. Since water is polarized, these movements create large-amplitude electrostatic fluctuations, sufficient to modify displacements of groups inside the protein and yield reorganization energies of protein electron transfer far exceeding those found for small molecules. Water follows adiabatically the protein motions. Therefore, the relaxation times of the protein and its hydration layer are close, leading to matching temperatures of the dynamical transition for the two components. © 2011 American Chemical Society.


Redman C.L.,Arizona State University
Ecology and Society | Year: 2014

It has become common for sustainability science and resilience theory to be considered as complementary approaches. Occasionally the terms have been used interchangeably. Although these two approaches share some working principles and objectives, they also are based on some distinct assumptions about the operation of systems and how we can best guide these systems into the future. Each approach would benefit from some scholars keeping sustainability science and resilience theory separate and focusing on further developing their distinctiveness and other scholars continuing to explore them in combination. Three areas of research in which following different procedures might be beneficial are whether to prioritize outcomes or system dynamics, how best to take advantage of community input, and increasing the use of knowledge of the past as a laboratory for potential innovations. © 2014 by the author(s).


Understanding and evaluating the factors that influence the persistence of small populations and establishment of new populations are basic goals of conservation biology. Genetic effects due to genetic drift and inbreeding can have important impacts on the success of new populations. Many bighorn sheep populations in western North America have had low numbers and many have gone extinct. Here, the possible effects of genetic drift and inbreeding are evaluated in three populations of desert bighorn sheep initiated in the 1970s from translocations. One of these has no molecular genetic data but has substantial demographic data (Aravaipa Canyon), one has both extensive demographic data and some molecular genetic data (Red Rock), and one has limited demographic data and some molecular genetic data (Tiburon Island). Overall, either from theoretical pedigree analysis and population genetic estimates from demographic history (Aravaipa, Tiburon) or from molecular data (Red Rock, Tiburon), it appears that the levels of genetic drift and inbreeding are substantial in all of these populations. This impact was larger when higher variance in male reproductive success was assumed. In other words, it appears that genetic factors are and will be important in the establishment and persistence of these populations. These examples in long-term monitored bighorn sheep populations are relevant to many endangered species in similar situations where demographic data are available but there is little or no historical molecular genetic data. © 2013 The Zoological Society of London.


Marean C.W.,Arizona State University
Journal of Human Evolution | Year: 2014

The systematic exploitation of marine foods by terrestrial mammals lacking aquatic morphologies is rare. Widespread ethnographic and archaeological evidence from many areas of the world shows that modern humans living on coastlines often ratchet up the use of marine foods and develop social and technological characteristics unusual to hunter-gatherers and more consistent with small scale food producing societies. Consistent use of marine resources often is associated with reduced mobility, larger group size, population packing, smaller territories, complex technologies, increased economic and social differentiation, and more intense and wide-ranging gifting and exchange. The commitment to temporally and spatially predictable and dense coastal foods stimulates investment in boundary defense resulting in inter-group conflict as predicted by theory and documented by ethnography. Inter-group conflict provides an ideal context for the proliferation of intra-group cooperative behaviors beneficial to the group but not to the altruist (Bowles, 2009). The origins of this coastal adaptation marks a transformative point for the hominin lineage in Africa since all previous adaptive systems were likely characterized by highly mobile, low-density, egalitarian populations with large territories and little boundary defense. It is important to separate occasional uses of marine foods, present among several primate species, from systematic and committed coastal adaptations. This paper provides a critical review of where and when systematic use of coastal resources and coastal adaptations appeared in the Old World by a comparison of the records from Africa and Europe. It is found that during the Middle Stone Age in South Africa there is evidence that true coastal adaptations developed while there is, so far, a lack of evidence for even the lowest levels of systematic coastal resource use by Neanderthals in Europe. Differences in preservation, sample size, and productivity between these regions do not explain the pattern. © 2014 Elsevier Ltd.


Lindsay S.,Arizona State University
Journal of Physics Condensed Matter | Year: 2012

Two recent developments portend a new era for silicon electronics in biomedical applications. Firstly, highly specific chemical recognition and massively parallel sample preparation techniques are being combined with VLSI to make new kinds of analytical chips. Secondly, critical dimensions are beginning to approach the size of biomolecules, opening new pathways for physical interactions between molecules and semiconductor structures. Future generations of hybrid chemicalCMOS devices could revolutionize diagnosis and make personalized medicine cheap enough to become widespread. © 2012 IOP Publishing Ltd.


Williams L.R.,Arizona State University | Steinberg L.,Temple University
Child Development | Year: 2011

The over-time reciprocal links between parenting and adolescent adjustment were examined in a sample of 1,354 serious adolescent offenders followed for 3years (16years of age at baseline, SD=1.14). Parallel processing growth curve models provided independent estimates of the impact of parenting on adolescent functioning as well as the impact of adolescent functioning on parenting. Positive adolescent development was facilitated by high parental warmth and low parental hostility. Parental monitoring predicted less problematic behavior, but less positive functioning as well. Predictably, parents became warmer and less hostile in response to positive adolescent development, and less warm in response to problematic adolescent functioning. Parental monitoring declined when adolescents exhibited either positive or problematic functioning. © 2011 The Authors. Child Development © 2011 Society for Research in Child Development, Inc..


Woodall W.H.,Virginia Polytechnic Institute and State University | Montgomery D.C.,Arizona State University
Journal of Quality Technology | Year: 2014

The purpose of this paper is to provide an overview and our perspective of recent research and applications of statistical process monitoring. The focus is on work done over the past decade or so. We review briefly a number of important areas, including health-related monitoring, spatiotemporal surveillance, profile monitoring, use of autocorrelated data, the effect of estimation error, and high-dimensional monitoring, among others. We briefly discuss the choice of performance metrics. We provide references and offer some directions for further research.


Stojanowski C.M.,Arizona State University
Journal of Human Evolution | Year: 2014

The Iwo Eleru site in Nigeria preserves the only terminal Pleistocene fossil from tropical West Africa. The peoples of this region contributed to significant population movements throughout the continent during the Holocene. As such, characterizing the phenotype of Late Pleistocene West African populations is critical for disentangling the evolutionary signatures of a highly complex African population history and structure. Previous research approached the calvaria's morphology from a paleoanthropological perspective, noting its mosaic of archaic and modern neurocranial features and distinctiveness from Pleistocene fossil taxa and contemporary modern human samples. In this paper, I compare Iwo Eleru with contemporary Late Pleistocene Africans and also consider the specimen's affinities with Holocene populations of the central and western Sahara, Nile Valley, and East Africa. Craniometric data were recorded for 22 neurocranial dimensions and subjected to principal components analysis and Mahalanobis distance estimation. Multidimensional scaling of distances indicated that Iwo Eleru fell outside the observed range of variation of other terminal Pleistocene supra-equatorial African populations, confirming previous results that documented its divergence from Neanderthals, Upper Paleolithic Europeans, and modern Africans. The calvaria was also distinct from Holocene Saharan, Nile Valley, and East African populations, which suggests limited West African input into the Sahara during the African Humid Period. Results presented here bolster previous research that suggested Iwo Eleru's anatomy reflected either admixture with archaic humans or the long-term survival of populations with more archaic neurocranial anatomy until the end of the Pleistocene. © 2014 Elsevier Ltd.


Murray A.T.,Arizona State University
Journal of Geographical Systems | Year: 2010

Geographic information systems (GIS) have matured and proven to be an enabling technology, one that is important to many disciplines. Location analysis is also a field that has matured and continues to evolve. In fact, the combination of GIS and location science is at the forefront of advances in spatial analysis capabilities, offering substantial potential for continued and sustained theoretical and empirical evolution. This paper provides an overview of location analysis and discusses GIS. The paper highlights how GIS has contributed to location science in terms of data input, visualization, problem solution and theoretical advances. The significance of GIS in this context is that it is far more than a mere spatial data input mechanism, which is a commonly held misconception within geography, operations research and other allied disciplines. In contrast to other reviews, the focus in this paper is to highlight the theoretical foundations of location analysis and modeling and how GIS is contributing to important advancements in this field. An overall contribution of the paper is providing a perspective on spatial analysis and how associated specialty areas are evolving and thriving, particularly as a component of GIScience. © 2010 Springer-Verlag.


Garvie L.A.J.,Arizona State University
American Mineralogist | Year: 2010

The proposition has been made and is now gaining popular acceptance that electron energy-loss spectroscopy (EELS) attached to a transmission electron microscope (TEM) can be used to semiquantitatively measure H in minerals-specifically, that there is a pre-peak to the O K edge near 530 eV whose intensity is a measure of H concentration in OH- and H2O- bearing minerals. I show here that the O K edges from H-bearing minerals, free of electron-beam damage, lack, a peak near 530 eV. Instead, under electron irradiation, in the TEM, a transient peak, near 530 eV can form in H-bearing as well as anhydrous minerals. The intensity of the transient peak is dependent on total fluence and fluence rate. The origin of the radiation-induced peak at 530 eV is from O2 liberated during damage by the incident, electron beam. In conclusion, there is no evidence for an OH peak near 530 eV from H-bearing minerals.


Scannapieco E.,Arizona State University | Bruggen M.,University of Hamburg
Astrophysical Journal | Year: 2015

To better understand the nature of the multiphase material found in outflowing galaxies, we study the evolution of cold clouds embedded in flows of hot and fast material. Using a suite of adaptive mesh refinement simulations that include radiative cooling, we investigate both cloud mass loss and cloud acceleration under the full range of conditions observed in galaxy outflows. The simulations are designed to track the cloud center of mass, enabling us to study the cloud evolution at long disruption times. For supersonic flows, a Mach cone forms around the cloud, which damps the Kelvin-Helmholtz instability but also establishes a streamwise pressure gradient that stretches the cloud apart. If time is expressed in units of the cloud crushing time, both the cloud lifetime and the cloud acceleration rate are independent of cloud radius, and we find simple scalings for these quantities as a function of the Mach number of the external medium. A resolution study suggests that our simulations accurately describe the evolution of cold clouds in the absence of thermal conduction and magnetic fields, physical processes whose roles will be studied in forthcoming papers. © 2015. The American Astronomical Society. All rights reserved.


Sabo J.L.,Arizona State University | Finlay J.C.,University of Minnesota | Kennedy T.,U.S. Geological Survey | Post D.M.,Yale University
Science | Year: 2010

Food chain length (FCL) is a fundamental component of food web structure. Studies in a variety of ecosystems suggest that FCL is determined by energy supply, environmental stability, and/or ecosystem size, but the nature of the relationship between environmental stability and FCL, and the mechanism linking ecosystem size to FCL, remain unclear. Here we show that FCL increases with drainage area and decreases with hydrologic variability and intermittency across 36 North American rivers. Our analysis further suggests that hydrologic variability is the mechanismunderlying the correlation between ecosystem size and FCL in rivers. Ecosystem size lengthens river food chains by integrating and attenuating discharge variation through stream networks, thereby enhancing environmental stability in larger river systems.


Anselin L.,Arizona State University
Papers in Regional Science | Year: 2010

In this paper, I give a personal view on the development of the field of spatial econometrics during the past 30 years. I argue that it has moved from the margins to the mainstream of applied econometrics and social science methodology. I distinguish three broad phases in the development, which I refer to as preconditions, take off and maturity. For each of these phases I describe the main methodological focus and list major contributions. I conclude with some speculations about future directions. Resumen: En este artículo, expongo mi opinión personal sobre el avance en el campo de la econometría espacial durante los últimos 30 años. Mi argumento es que ha pasado de estar en la periferia de la econometría espacial y la metodología de ciencias sociales a ser algo corriente. Hago la distinción entre tres fases principales en el avance, a las que denomino precondiciones, arranque y madurez. Para cada una de estas fases describo el objetivo metodológico principal y proporciono un listado con las contribuciones principales. Concluyo con especulaciones sobre posibles direcciones en el futuro. © 2010 the author(s). Journal compilation © 2010 RSAI.


Livengood P.,Arizona State University
BMC bioinformatics | Year: 2012

When analyzing metabolomics data, cancer care researchers are searching for differences between known healthy samples and unhealthy samples. By analyzing and understanding these differences, researchers hope to identify cancer biomarkers. Due to the size and complexity of the data produced, however, analysis can still be very slow and time consuming. This is further complicated by the fact that datasets obtained will exhibit incidental differences in intensity and retention time, not related to actual chemical differences in the samples being evaluated. Additionally, automated tools to correct these errors do not always produce reliable results. This work presents a new analytics system that enables interactive comparative visualization and analytics of metabolomics data obtained by two-dimensional gas chromatography-mass spectrometry (GC × GC-MS). The key features of this system are the ability to produce visualizations of multiple GC × GC-MS data sets, and to explore those data sets interactively, allowing a user to discover differences and features in real time. The system provides statistical support in the form of difference, standard deviation, and kernel density estimation calculations to aid users in identifying meaningful differences between samples. These are combined with novel transfer functions and multiform, linked visualizations in order to provide researchers with a powerful new tool for GC × GC-MS exploration and bio-marker discovery.


Sears M.W.,Clemson University | Angilletta M.J.,Arizona State University
American Naturalist | Year: 2015

In recent years, ecologists have stepped up to address the challenges imposed by rapidly changing climates. Some researchers have developed niche-based methods to predict how species will shift their ranges. Such methods have evolved rapidly, resulting in models that incorporate physiological and behavioral mechanisms. Despite their sophistication, these models fail to account for environmental heterogeneity at the scale of an organism. We used an individual-based model to quantify the effects of operative environmental temperatures, as well as their heterogeneity and spatial structure, on the thermoregulation, movement, and energetics of ectotherms. Our simulations showed that the heterogeneity and spatial structure of a thermal landscape are as important as its mean temperature. In fact, temperature and heterogeneity interact to determine organismal performance. Consequently, the popular index of environmental quality (de), which ignores variance and spatial structure, is inherently flawed as a descriptor of the thermal quality of an environment. Future efforts to model species’ distributions should link thermoregulation and activity to environmental heterogeneity at fine scales. © 2015 by The University of Chicago. All rights reserved.


Liu H.,Arizona State University
Data Mining and Knowledge Discovery | Year: 2011

Social media has reshaped the way in which people interact with each other. The rapid development of participatory web and social networking sites like YouTube, Twitter, and Facebook, also brings about many data mining opportunities and novel challenges. In particular, we focus on classification tasks with user interaction information in a social network. Networks in social media are heterogeneous, consisting of various relations. Since the relation-type information may not be available in social media, most existing approaches treat these inhomogeneous connections homogeneously, leading to an unsatisfactory classification performance. In order to handle the network heterogeneity, we propose the concept of social dimension to represent actors' latent affiliations, and develop a classification framework based on that. The proposed framework, SocioDim, first extracts social dimensions based on the network structure to accurately capture prominent interaction patterns between actors, then learns a discriminative classifier to select relevant social dimensions. SocioDim, by differentiating different types of network connections, outperforms existing representative methods of classification in social media, and offers a simple yet effective approach to integrating two types of seemingly orthogonal information: the network of actors and their attributes. © The Author(s) 2010.


Marzke M.W.,Arizona State University
Philosophical transactions of the Royal Society of London. Series B, Biological sciences | Year: 2013

Was stone tool making a factor in the evolution of human hand morphology? Is it possible to find evidence in fossil hominin hands for this capability? These questions are being addressed with increasingly sophisticated studies that are testing two hypotheses; (i) that humans have unique patterns of grip and hand movement capabilities compatible with effective stone tool making and use of the tools and, if this is the case, (ii) that there exist unique patterns of morphology in human hands that are consistent with these capabilities. Comparative analyses of human stone tool behaviours and chimpanzee feeding behaviours have revealed a distinctive set of forceful pinch grips by humans that are effective in the control of stones by one hand during manufacture and use of the tools. Comparative dissections, kinematic analyses and biomechanical studies indicate that humans do have a unique pattern of muscle architecture and joint surface form and functions consistent with the derived capabilities. A major remaining challenge is to identify skeletal features that reflect the full morphological pattern, and therefore may serve as clues to fossil hominin manipulative capabilities. Hominin fossils are evaluated for evidence of patterns of derived human grip and stress-accommodation features.


Brackney R.J.,Arizona State University
Journal of the experimental analysis of behavior | Year: 2011

Dissociating motoric and motivational effects of pharmacological manipulations on operant behavior is a substantial challenge. To address this problem, we applied a response-bout analysis to data from rats trained to lever press for sucrose on variable-interval (VI) schedules of reinforcement. Motoric, motivational, and schedule factors (effort requirement, deprivation level, and schedule requirements, respectively) were manipulated. Bout analysis found that interresponse times (IRTs) were described by a mixture of two exponential distributions, one characterizing IRTs within response bouts, another characterizing intervals between bouts. Increasing effort requirement lengthened the shortest IRT (the refractory period between responses). Adding a ratio requirement increased the length and density of response bouts. Both manipulations also decreased the bout-initiation rate. In contrast, food deprivation only increased the bout-initiation rate. Changes in the distribution of IRTs over time showed that responses during extinction were also emitted in bouts, and that the decrease in response rate was primarily due to progressively longer intervals between bouts. Taken together, these results suggest that changes in the refractory period indicate motoric effects, whereas selective alterations in bout initiation rate indicate incentive-motivational effects. These findings support the use of response-bout analyses to identify the influence of pharmacological manipulations on processes underlying operant performance.


Hruschka D.J.,Arizona State University | Burger O.,University of Kent
Philosophical Transactions of the Royal Society B: Biological Sciences | Year: 2016

Most work on the human fertility transition has focused on declines in mean fertility. However, understanding changes in the variance of reproductive outcomes can be equally important for evolutionary questions about the heritability of fertility, individual determinants of fertility and changing patterns of reproductive skew. Here, we document how variance in completed fertility among women (45-49 years) differs across 200 surveys in 72 low- to middle-income countries where fertility transitions are currently in progress at various stages. Nearly all (91%) of samples exhibit variance consistent with a Poisson process of fertility, which places systematic, and often severe, theoretical upper bounds on the proportion of variance that can be attributed to individual differences. In contrast to the pattern of total variance, these upper bounds increase from high- to mid-fertility samples, then decline again as samples move from mid to low fertility. Notably, the lowest fertility samples often deviate from a Poisson process. This suggests that as populations move to low fertility their reproduction shifts from a rate-based process to a focus on an ideal number of children. We discuss the implications of these findings for predicting completed fertility from individual-level variables. © 2016 The Author(s) Published by the Royal Society. All rights reserved.


Bishop N.J.,Arizona State University
Drug and Alcohol Dependence | Year: 2011

Background: This project examined the ability of the popular DUI/DWI offender assessment instrument, the Driver Risk Inventory (DRI; Behavior Data Systems, Ltd., 1985), to identify short-term DUI recidivists in a sample of Floridian DUI offenders who were charged with DUI between January 1st, 2008 and December 31st, 2009. The DRI provides a number of behavioral risk scales, DSM-IV substance abuse and dependence classifications, as well as measurement of demographic and criminal history characteristics. Methods: Cox proportional hazards models were used to identify the demographic, criminal history, and behavioral characteristics most closely associated with the risk of rapid DUI recidivism. Follow-up analyses including ROC curves were used to further examine the ability of the DRI to identify short-term DUI recidivists. Results: In the final model controlling for all variables, the DRI driver risk scale was the single strongest predictor of rapid DUI recidivism. The DSM-IV substance abuse and dependence classifications were also significant predictors of DUI recidivism. A number of the DRI risk scales and the DSM-IV classifications exhibited significant predictive validity and exhibited sensitivity in identifying recidivists similar to other popular DUI offender assessment instruments. Conclusions: The DRI provides useful identification of DUI recidivists in a sample able to capture only the most rapid DUI recidivists. The results of this research warrant further examination of the DRI's ability to identify DUI recidivists using longer intervals of time between DUI arrests. © 2011 Elsevier Ireland Ltd.


Dorn R.I.,Arizona State University
Geomorphology | Year: 2011

A half century ago C.D. Ollier proposed that insolation-driven temperature changes expand and contract fill in fissures enough to widen cracks, a process that would permit progressively deeper penetration of fissure fills, that would in turn generate a positive feedback of greater and greater strain until desert boulders and bedrock shatters. Although desert physical weathering by "dirt cracking" has occasionally been cited, this hypothesized process remains without support from subsequent research. Here, field observations, electron microscopy, X-ray powder diffraction, particle-size analysis, and laboratory experiments shed new light on dirt cracking. Little clear evidence supports the original notion of expansive pressures from thermal fluctuations. However, mineralogical, high resolution transmission electron microscopy, back-scattered electron microscopy, and experimental evidence support two alternative processes of widening fractures: wetting and drying of fills inside fissures; and the precipitation and remobilization of calcium carbonate. A re-envisioned dirt-cracking wedging process starts with calcium carbonate precipitating in fissures less than 5μm wide. First precipitation, and then ongoing dissolution of this laminar calcrete, opens enough space for dust to penetrate into these narrow fractures. Wetting of expansive clays in the fissure fill exerts enough pressure to widen and deepen the fissure, allowing the carbonate precipitation process to penetrate even deeper and allowing even more dust to move into a fracture. As the dust infiltrates, its texture changes from a chaotic mix of particles to an alignment of clays parallel to fissure sides. This parallel alignment could increase the efficiency of fill wedging. Ollier's concept of a positive feedback remains supported; each increment of fracture deepening and widening permits more, even deeper infiltration of laminar calcrete and dust. Field and electron microscope observations of rock spalling in the winter of 2010 are consistent with Ollier's hypothesis that dirt cracking is a common physical weathering process in deserts that splits rocks of all different sizes. © 2011 Elsevier B.V.


Rosenberg M.S.,Arizona State University
PLoS ONE | Year: 2010

The common formula used for converting a chi-square test into a correlation coefficient for use as an effect size in metaanalysis has a hidden assumption which may be violated in specific instances, leading to an overestimation of the effect size. A corrected formula is provided. © 2010 Michael S. Rosenberg.


A theory for impurity segregation in electrochemical processes is formulated based on the Nernst equation, which forms the theoretical foundation for electrorefining. It is found that the current two-electrode configuration, while being widely used to purify metals, is incapable of producing ultrahigh purity. A three-electrode configuration is required, in which the potential applied to the anode or the cathode with respect to the reference electrode is the key to produce ultrapure materials. The theory is applied to electrorefining of metallurgical-grade silicon to produce solar-grade silicon. It is suggested that two-step electrorefining is required to remove all the impurities, in which the anode and cathode potentials are controlled in separate steps. The precise anode and cathode potentials for each step are determined from the impurity concentrations in metallurgical-grade silicon and the target impurity concentrations for solar-grade silicon. It is also found that low process temperatures promote effective electrorefining. © 2012 Elsevier Ltd. All Rights Reserved.


Deng H.,Intuit | Runger G.,Arizona State University
Pattern Recognition | Year: 2013

The regularized random forest (RRF) was recently proposed for feature selection by building only one ensemble. In RRF the features are evaluated on a part of the training data at each tree node. We derive an upper bound for the number of distinct Gini information gain values in a node, and show that many features can share the same information gain at a node with a small number of instances and a large number of features. Therefore, in a node with a small number of instances, RRF is likely to select a feature not strongly relevant. Here an enhanced RRF, referred to as the guided RRF (GRRF), is proposed. In GRRF, the importance scores from an ordinary random forest (RF) are used to guide the feature selection process in RRF. Experiments on 10 gene data sets show that the accuracy performance of GRRF is, in general, more robust than RRF when their parameters change. GRRF is computationally efficient, can select compact feature subsets, and has competitive accuracy performance, compared to RRF, varSelRF and LASSO logistic regression (with evaluations from an RF classifier). Also, RF applied to the features selected by RRF with the minimal regularization outperforms RF applied to all the features for most of the data sets considered here. Therefore, if accuracy is considered more important than the size of the feature subset, RRF with the minimal regularization may be considered. We use the accuracy performance of RF, a strong classifier, to evaluate feature selection methods, and illustrate that weak classifiers are less capable of capturing the information contained in a feature subset. Both RRF and GRRF were implemented in the "RRF" R package available at CRAN, the official R package archive. © 2013 Elsevier Ltd.


Rein S.,TU Berlin | Reisslein M.,Arizona State University
IEEE Communications Surveys and Tutorials | Year: 2011

The computational and memory resources of wireless sensor nodes are typically very limited, as the employed low-energy microcontrollers provide only hardware support for 16 bit integer operations and have very limited random access memory (RAM). These limitations prevent the application of modern signal processing techniques to pre-process the collected sensor data for energy and bandwidth efficient transmission over sensor networks. This tutorial introduces communication and networking generalists without a background in wavelet signal processing to low-memory wavelet transform techniques. We first explain the one-dimensional wavelet transform (including the lifting scheme for in-place computation), the two-dimensional wavelet transform, as well as the evaluation of wavelet transforms with fixed-point arithmetic. Then, we explain the fractional wavelet filter technique which computes wavelet transforms with 16 bit integers and requires less than 1.5 kByte of RAM for a 256 x 256 gray scale image. We present case studies illustrating the use of these low-memory wavelet techniques in conjunction with image coding systems to achieve image compression competitive to the JPEG2000 standard on resource-constrained wireless sensor nodes. We make the C-code software for the techniques introduced in this tutorial freely available. © 2011 IEEE.


Behavior such as depression of a lever or perception of a stimulus may be strengthened by consequent behaviorally significant events (BSEs), such as reinforcers. This is the Law of Effect. As time passes since its emission, the ability for the behavior to be reinforced decreases. This is trace decay. It is upon decayed traces that subsequent BSEs operate. If the trace comes from a response, it constitutes primary reinforcement; if from perception of an extended stimulus, it is classical conditioning. This paper develops simple models of these processes. It premises exponentially decaying traces related to the richness of the environment, and conditioned reinforcement as the average of such traces over the extended stimulus, yielding an almost-hyperbolic function of duration. The models account for some data, and reinforce the theories of other analysts by providing a sufficient account of the provenance of these effects. It leads to a linear relation between sooner and later isopreference delays whose slope depends on sensitivity to reinforcement, and intercept on that and the steepness of the delay gradient. Unlike human prospective judgments, all control is vested in either primary or secondary reinforcement processes; therefore the use of the term discounting, appropriate for humans, may be less descriptive of the behavior of nonverbal organisms. © 2011 Elsevier B.V.


Tashiro H.,Arizona State University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

The 21 cm signatures induced by moving cosmic string loops are investigated. Moving cosmic string loops seed filamentary nonlinear objects. We analytically evaluate the differential 21 cm brightness temperature from these objects. We show that the brightness temperature reaches 200 mK for a loop whose tension is about the current upper limit, Gμ∼10-7. We also calculate the angular power spectrum, assuming scaling in loop distribution. We find that the angular power spectrum for Gμ>10-8 at z=30 or Gμ>10-10 at z=20 can dominate the spectrum of the primordial density fluctuations. Finally we show that a future SKA-like observation has the potential to detect the power spectrum due to loops with Gμ=10-8 at z=20. © 2013 American Physical Society.


Ditto W.L.,Arizona State University
Chaos (Woodbury, N.Y.) | Year: 2010

Chaotic systems can yield a wide variety of patterns. Here we use this feature to generate all possible fundamental logic gate functions. This forms the basis of the design of a dynamical computing device, a chaogate, that can be rapidly morphed to become any desired logic gate. Here we review the basic concepts underlying this and present an extension of the formalism to include asymmetric logic functions.


Pizzarello S.,Arizona State University
Cold Spring Harbor perspectives in biology | Year: 2010

Carbon-containing meteorites provide a natural sample of the extraterrestrial organic chemistry that occurred in the solar system ahead of life's origin on the Earth. Analyses of 40 years have shown the organic content of these meteorites to be materials as diverse as kerogen-like macromolecules and simpler soluble compounds such as amino acids and polyols. Many meteoritic molecules have identical counterpart in the biosphere and, in a primitive group of meteorites, represent the majority of their carbon. Most of the compounds in meteorites have isotopic compositions that date their formation to presolar environments and reveal a long and active cosmochemical evolution of the biogenic elements. Whether this evolution resumed on the Earth to foster biogenesis after exogenous delivery of meteoritic and cometary materials is not known, yet, the selective abundance of biomolecule precursors evident in some cosmic environments and the unique L-asymmetry of some meteoritic amino acids are suggestive of their possible contribution to terrestrial molecular evolution.


Lebed R.F.,Arizona State University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

Following Weinberg's argument that narrow tetraquark mesons are not precluded in large Nc QCD, we explore the flow of Nc factors needed for the consistency of this picture and show that they must arise in a novel way, not simply through the usual combinatoric counting. © 2013 American Physical Society.


Posfai M.,University of Pannonia | Buseck P.R.,Arizona State University
Annual Review of Earth and Planetary Sciences | Year: 2010

Aerosol particles in the atmosphere exert a strong influence on climate by interacting with sunlight and by initiating cloud formation. Because the tropospheric aerosol is a heterogeneous mixture of various particle types, its climate effects can only be fully understood through detailed knowledge of the physical and chemical properties of individual particles. Here we review the results of individual-particle studies that use microscopy-based techniques, emphasizing transmission electron microscopy and focusing on achievements of the past ten years. We discuss the techniques that are best suited for studying distinct particle properties and provide a brief overview of major particle types, their identification, and their sources. The majority of this review is concerned with the optical properties and hygroscopic behavior of aerosol particles; we discuss recent results and highlight the potential of emerging microscopy techniques for analyzing the particle properties that contribute most to climate effects. Copyright © 2010 by Annual Reviews. All rights reserved.


Nielsen D.R.,Arizona State University
Microbial cell factories | Year: 2014

BACKGROUND: Styrene is an important building-block petrochemical and monomer used to produce numerous plastics. Whereas styrene bioproduction by Escherichia coli was previously reported, the long-term potential of this approach will ultimately rely on the use of hosts with improved industrial phenotypes, such as the yeast Saccharomyces cerevisiae.RESULTS: Classical metabolic evolution was first applied to isolate a mutant capable of phenylalanine over-production to 357 mg/L. Transcription analysis revealed up-regulation of several phenylalanine biosynthesis pathway genes including ARO3, encoding the bottleneck enzyme DAHP synthase. To catalyze the first pathway step, phenylalanine ammonia lyase encoded by PAL2 from A. thaliana was constitutively expressed from a high copy plasmid. The final pathway step, phenylacrylate decarboxylase, was catalyzed by the native FDC1. Expression of FDC1 was naturally induced by trans-cinnamate, the pathway intermediate and its substrate, at levels sufficient for ensuring flux through the pathway. Deletion of ARO10 to eliminate the competing Ehrlich pathway and expression of a feedback-resistant DAHP synthase encoded by ARO4K229L preserved and promoted the endogenous availability precursor phenylalanine, leading to improved pathway flux and styrene production. These systematic improvements allowed styrene titers to ultimately reach 29 mg/L at a glucose yield of 1.44 mg/g, a 60% improvement over the initial strain.CONCLUSIONS: The potential of S. cerevisiae as a host for renewable styrene production has been demonstrated. Significant strain improvements, however, will ultimately be needed to achieve economical production levels.


While some literature has explored women's sexual satisfaction and, to a lesser degree, women's faking orgasm experiences, little research has examined the context and conditions around women's best and most memorable orgasms. This paper utilised thematic analysis of qualitative data from a community sample of 20 women in the USA (mean age = 34 years, SD = 13.35 years) from a wide range of racial, socioeconomic, and sexual identity backgrounds to illuminate their experiences with fake or pretend orgasms, and with their best orgasms. While faking orgasm narratives reflected themes of wanting to reinforce a partner's sexual skills, strategically ending sexual interactions, and suppressing feelings of abnormality and shame, best orgasm experiences showcased the power of interpersonal connection, the joys of masturbation and other non-penile-vaginal intercourse behaviours, and the significance of 'transformative embodiment'. Implications for the relative failures of (hetero)sex, particularly in the context of gendered power imbalances, along with the importance of deconstructing the sexually 'functional' or 'dysfunctional' woman are explored. © 2014 Taylor & Francis.


Jadhao V.,Northwestern University | Solis F.J.,Arizona State University | De La Cruz M.O.,Northwestern University
Physical Review Letters | Year: 2012

For charged systems in heterogeneous dielectric media, a key obstacle for molecular dynamics (MD) simulations is the need to solve the Poisson equation in the media. This obstacle can be bypassed using MD methods that treat the local polarization charge density as a dynamic variable, but such approaches require access to a true free energy functional, one that evaluates to the equilibrium electrostatic energy at its minimum. In this Letter, we derive the needed functional. As an application, we develop a Car-Parrinello MD method for the simulation of free charges present near a spherical emulsion droplet separating two immiscible liquids with different dielectric constants. Our results show the presence of nonmonotonic ionic profiles in the dielectric with a lower dielectric constant. © 2012 American Physical Society.


Stahlschmidt Z.R.,Arizona State University
PLoS ONE | Year: 2011

Parental care (any non-genetic contribution by a parent that appears likely to increase the fitness of its offspring) is a widespread trait exhibited by a broad range of animal taxa. In addition to influencing the fitness of parent(s) and offspring, parental care may be inextricably involved in other evolutionary processes, such as sexual selection and the evolution of endothermy. Yet, recent work has demonstrated that bias related to taxonomy is prevalent across many biological disciplines, and research in parental care may be similarly burdened. Thus, I used parental care articles published in six leading journals of fundamental behavioral sciences (Animal Behaviour, Behavioral Ecology, Behavioral Ecology and Sociobiology, Ethology, Hormones and Behavior, and Physiology & Behavior) from 2001-2010 (n = 712) to examine the year-to-year dynamics of two types of bias related to taxonomy across animals: (1) taxonomic bias, which exists when research output is not proportional to the frequency of organisms in nature, and (2) taxonomic citation bias, which is a proxy for the breadth of a given article-specifically, the proportion of articles cited that refer solely to the studied taxon. I demonstrate that research on birds likely represents a disproportionate amount of parental care research and, thus, exhibits taxonomic bias. Parental care research on birds and mammals also refers to a relatively narrow range of taxonomic groups when discussing its context and, thus, exhibits taxonomic citation bias. Further, the levels of taxonomic bias and taxonomic citation bias have not declined over the past decade despite cautionary messages about similar bias in related disciplines- in fact, taxonomic bias may have increased. As in Bonnet et al. (2002), my results should not be interpreted as evidence of an 'ornithological Mafia' conspiring to suppress other taxonomic groups. Rather, I generate several rational hypotheses to determine why bias persists and to guide future work. © 2011 Zachary R. Stahlschmidt.


Wang X.,Arizona State University
Biochemistry | Year: 2012

Decorin-binding protein A (DBPA) is an important lipoprotein from the bacterium Borrelia burgdorferi, the causative agent of Lyme disease. The absence of DBPA drastically reduces the pathogenic potential of the bacterium, and biochemical evidence indicates DBPA's interactions with the glycosaminoglycan (GAG) portion of decorin are crucial to its function. We have determined the solution structure of DBPA and studied DBPA's interactions with various forms of GAGs. DBPA is determined to be a helical bundle protein consisting of five helices held together by a strong hydrophobic core. The structure also possesses a basic patch formed by portions of two helices and two flexible linkers. Low-molecular mass heparin-induced chemical shift perturbations for residues in the region as well as increases in signal intensities of select residues in their presence confirm residues in the pocket are perturbed by heparin binding. Dermatan sulfate fragments, the dominant GAG type found on decorin, were shown to have lower affinity than heparin but are still capable of binding DBPA. © 2012 American Chemical Society.


Colbourn C.J.,Arizona State University
Designs, Codes, and Cryptography | Year: 2010

For a prime power q ≡ 1 (mod{v}), the q × q cyclotomic matrix, whose entries are the discrete logarithms modulo v of the entries in the addition table of Fq, has been shown using character theoretic arguments to produce an ε-biased array, provided that q is large enough as a function of v and ε . A suitable choice of ε ensures that the array is a covering array of strength t when {q > t2 v4t . On the other hand, when v = 2, using a different character-theoretic argument the matrix has been shown to be a covering array of strength t when q > t 2 22t-2. The restrictions on ε -biased arrays are more severe than on covering arrays. This is exploited to prove that for all v ≥ 2, the matrix is a covering array of strength t whenever q > t 2 v2t, again using character theory. A number of constructions of covering arrays arise by developing and extending the cyclotomic matrix. For each construction, extensive computations for various choices of t and v are reported that determine the precise set of small primes for which the construction produces a covering array. As a consequence, many covering arrays are found when q is smaller than the bound t2 v 2t, and consequences for the existence of covering arrays reported. © 2009 Springer Science+Business Media, LLC.


Basu S.,Arizona State University | Francoeur M.,University of Utah
Optics Letters | Year: 2014

We investigate near-field radiative heat transfer between two thin films made of metamaterials. The impact of film thickness on magnetic and electric surface polaritons (ESPs) is analyzed. It is found that the strength as well as the location of magnetic resonance does not change with film thickness until the film behaves as semi-infinite for the dielectric function chosen in this study. When the film is thinner than vacuum gap, both electric and magnetic polaritons contribute evenly to near-field radiative heat transfer. At larger film thicknesses, ESPs dominate heat transfer due to excitation of a larger number of modes. Results obtained from this study will facilitate applications of metamaterials as thin-film coatings for energy systems. © 2014 Optical Society of America.


Herrmann M.,Arizona State University
Journal of Engineering for Gas Turbines and Power | Year: 2010

This paper presents numerical simulation results of the primary atomization of a turbulent liquid jet injected into a gaseous crossflow. Simulations are performed using the balanced force refined level set grid method. The phase interface during the initial breakup phase is tracked by a level set method on a separate refined grid. A balanced force finite volume algorithm together with an interface projected curvature evaluation is used to ensure the stable and accurate treatment of surface tension forces even on small scales. Broken off, small scale nearly spherical drops are transferred into a Lagrangian point particle description allowing for full two-way coupling and continued secondary atomization. The numerical method is applied to the simulation of the primary atomization region of a turbulent liquid jet (q=6.6, We=330, Re=14,000) injected into a gaseous crossflow (Re=570,000), analyzed experimentally by Brown and McDonell (2006, "Near Field Behavior of a Liquid Jet in a Crossflow," ILASS Americas, 19th Annual Conference on Liquid Atomization and Spray Systems). The simulations take the actual geometry of the injector into account. Grid converged simulation results of the jet penetration agree well with experimentally obtained correlations. Both column/bag breakup and shear/ligament breakup modes can be observed on the liquid jet. A grid refinement study shows that on the finest employed grids (flow solver 64 points per injector diameter, level set solver 128 points per injector diameter), grid converged drop sizes are achieved for drops as small as one-hundredth the size of the injector diameter. © 2010 by ASME.


Richert R.,Arizona State University
Thermochimica Acta | Year: 2011

Using propylene carbonate as an example for a glass-forming liquid with generic behaviour, a technique based on dielectric relaxation experiments at high electric fields is reviewed and explained in unprecedented detail. Analogous to microwave heating, the sample absorbs energy from the field, and the resulting configurational changes are measured and linked to the configurational modes of the heat capacity. Evidence is provided for the heterogeneous nature of the slow degrees of freedom that are responsible for the heat capacity step near Tg. Moreover, the thermal and dielectric relaxation times are not only subject to the same overall dispersion, but are locally correlated and the dielectric and thermal time constants are identical within a 15% margin. Only for the fastest few percent of the thermal relaxation times can deviations from these correlations be found. © 2010 Elsevier B.V. All rights reserved.


Franz N.M.,Arizona State University
Cladistics | Year: 2014

The sequential stages culminating in the publication of a morphological cladistic analysis of weevils in the Exophthalmus genus complex (Coleoptera: Curculionidae: Entiminae) are reviewed, with an emphasis on how early-stage homology assessments were gradually evaluated and refined in light of intermittent phylogenetic insights. In all, 60 incremental versions of the evolving character matrix were congealed and analysed, starting with an assembly of 52 taxa and ten traditionally deployed diagnostic characters, and ending with 90 taxa and 143 characters that reflect significantly more narrow assessments of phylogenetic similarity and scope. Standard matrix properties and analytical tree statistics were traced throughout the analytical process, and series of incongruence length indifference tests were used to identify critical points of topology change among succeeding matrix versions. This kind of parsimony-contingent rescoping is generally representative of the inferential process of character individuation within individual and across multiple cladistic analyses. The expected long-term outcome is a maturing observational terminology in which precise inferences of homology are parsimony-contingent, and the notions of homology and parsimony are inextricably linked. This contingent view of cladistic character individuation is contrasted with current approaches to developing phenotype ontologies based on homology-neutral structural equivalence expressions. Recommendations are made to transparently embrace the parsimony-contingent nature of cladistic homology. © The Willi Hennig Society 2013.


Richert R.,Arizona State University
Journal of Chemical Physics | Year: 2010

A recent dielectric study of various polyalcohols reported on the general occurrence of an ultraslow process with Debye type character in hydrogen bonded liquids [R. Bergman, H. Jansson, and J. Swenson, J. Chem. Phys. 132, 044504 (2010)], whereas previous work suggested that such behavior is specific to monoalcohols only. Clarifying this issue is highly relevant for assessing models aimed at rationalizing these modes that are slower than the primary structural relaxation and associated with a single time constant. To this end, the dielectric relaxation of glycerol is measured at different electrode distances with high accuracy. In this manner, electrode polarization can be separated from the dielectric signals intrinsic in the supercooled liquid. In the frequency range below the loss peak frequency ωmax of the α -process, only dc-conductivity is required to understand the dielectric properties of supercooled glycerol within a margin of ε″ ≈±0.1 and thus no indication of an ultraslow peak is found. More quantitatively, any dielectric Debye like mode located around 10-5 ωmax would need to have an amplitude smaller than 0.4% of that of the primary dielectric process to be consistent with the present findings, in contrast to previous claims of >50%. © 2010 American Institute of Physics.


Fried E.I.,Quantitative Group | Nesse R.M.,Arizona State University
Journal of Affective Disorders | Year: 2015

Background: The DSM-5 encompasses a wide range of symptoms for Major Depressive Disorder (MDD). Symptoms are commonly added up to sum-scores, and thresholds differentiate between healthy and depressed individuals. The underlying assumption is that all patients diagnosed with MDD have a similar condition, and that sum-scores accurately reflect the severity of this condition. To test this assumption, we examined the number of DSM-5 depression symptom patterns in the "Sequenced Treatment Alternatives to Relieve Depression" (STAR∗D) study. Methods: We investigated the number of unique symptom profiles reported by 3703 depressed outpatients at the beginning of the first treatment stage of STAR∗D. Results: Overall, we identified 1030 unique symptom profiles. Of these profiles, 864 profiles (83.9%) were endorsed by five or fewer subjects, and 501 profiles (48.6%) were endorsed by only one individual. The most common symptom profile exhibited a frequency of only 1.8%. Controlling for overall depression severity did not reduce the amount of observed heterogeneity. Limitations: Symptoms were dichotomized to construct symptom profiles. Many subjects enrolled in STAR∗D reported medical conditions for which prescribed medications may have affected symptom presentation. Conclusions: The substantial symptom variation among individuals who all qualify for one diagnosis calls into question the status of MDD as a specific consistent syndrome and offers a potential explanation for the difficulty in documenting treatment efficacy. We suggest that the analysis of individual symptoms, their patterns, and their causal associations will provide insights that could not be discovered in studies relying on only sum-scores. © 2014 Elsevier B.V. All rights reserved.


Pizzarello S.,Arizona State University
Astrophysical Journal Letters | Year: 2012

Carbonaceous chondrites are meteorites that may contain abundant organic materials, including soluble compounds as diverse as amino acids and hydrocarbons. We report here the finding of hydrogen cyanide in the Murchison meteorite in amounts ≤ 10ppm. HCN was never searched for in meteorites and its detection in sizeable amount is surprising in view of the extensive water phase that is recorded by the petrology of this type of meteorites and could have exhausted their HCN content through multiple reactions. The finding adds to the inventory of simple volatile molecules found in both comets and meteorites. © 2012. The American Astronomical Society. All rights reserved..


Solids of nearly solar composition have interacted with aqueous fluids on carbonaceous asteroids, icy moons, and trans-neptunian objects. These processes altered mineralogy of accreted materials together with compositions of aqueous and gaseous phases. We evaluated chemistry of aqueous solutions coexisted with CI-type chondritic solids through calculations of chemical equilibria in closed water-rock-gas systems at different compositions of initial fluids, water/rock mass ratios (0.1-1000), temperatures (<350°C), and pressures (<2kbars). The calculations show that fluid compositions are mainly affected by solubilities of solids, the speciation of chlorine in initial water-rock mixtures, and the occurrence of Na-bearing secondary minerals such as saponite. The major species in modeled alkaline solutions are Na +, Cl -, CO32-,HCO3-, K +, OH -, H 2, and CO 2. Aqueous species of Mg, Fe, Ca, Mn, Al, Ni, Cr, S, and P are not abundant in these fluids owing to low solubility of corresponding solids. Typical NaCl type alkaline fluids coexist with saponite-bearing mineralogy that usually present in aqueously altered chondrites. A common occurrence of these fluids is consistent with the composition of grains emitted from Enceladus. Na-rich fluids with abundant CO32-,HCO3-, and OH - anions coexist with secondary mineralogy depleted in Na. The Na 2CO 3 and NaHCO 3 type fluids could form via accretion of cometary ices. NaOH type fluids form in reduced environments and may locally occur on parent bodies of CR carbonaceous chondrites. Supposed melting of accreted HCl-bearing ices leads to early acidic fluids enriched in Mg, Fe and other metals, consistent with signs of low-pH alteration in chondrites. Neutralization of these solutions leads to alkaline Na-rich fluids. Sulfate species have negligible concentrations in closed systems, which remain reduced, especially at elevated pressures created by forming H 2 gas. Hydrogen, CO 2, and H 2O dominate in the gaseous phase, though the abundance of methane cannot be fairly estimated. © 2012 Elsevier Inc.


O'Keeffe M.,Arizona State University
Physical Chemistry Chemical Physics | Year: 2010

Attention is called to some little-discussed aspects of crystal structure prediction. It is pointed out that the structures of metal-organic frameworks can often be correctly predicted. This allows designed synthesis of materials with targeted pore size and functionality. For more-conventional inorganic materials, predicting the lowest energy state can be made difficult by two problems. First, the difference in energy between competing structures can be very small. Second, the unit cells of materials with simple compositions may be very large. Examples are given for both cases. © 2010 The Owner Societies.


Davies P.C.W.,Arizona State University
Interface Focus | Year: 2012

Genes store heritable information, but actual gene expression often depends on many so-called epigenetic factors, both physical and chemical, external to DNA. Epigenetic changes can be both reversible and heritable. The genome is associated with a physical object (DNA) with a specific location, whereas the epigenome is a global, systemic, entity. Furthermore, genomic information is tied to specific coded molecular sequences stored in DNA. Although epigenomic information can be associated with certain non-DNA molecular sequences, it is mostly not. Therefore, there does not seem to be a stored 'epigenetic programme' in the information-theoretic sense. Instead, epigenomic control is-to a large extent-an emergent self-organizing phenomenon, and the real-time operation of the epigenetic 'project' lies in the realm of nonlinear bifurcations, interlocking feedback loops, distributed networks, top-down causation and other concepts familiar from the complex systems theory. Lying at the heart of vital eukaryotic processes are chromatin structure, organization and dynamics. Epigenetics provides striking examples of how bottom-up genetic and top-down epigenetic causation intermingle. The fundamental question then arises of how causal efficacy should be attributed to biological information. A proposal is made to implement explicit downward causation by coupling information directly to the dynamics of chromatin, thus permitting the coevolution of dynamical laws and states, and opening up a new sector of dynamical systems theory that promises to display rich self-organizing and self-complexifying behaviour. © 2011 The Royal Society.


He Y.,Zhejiang Normal University | Li B.,University of Texas at San Antonio | O'Keeffe M.,Arizona State University | Chen B.,University of Texas at San Antonio
Chemical Society Reviews | Year: 2014

Metal-organic frameworks (MOFs), also known as porous coordination polymers (PCPs), are an emerging type of porous materials which are formed by the self-assembly of metallic centers and bridging organic linkers. Design and synthesis of organic linkers are very critical to target MOFs with desired structures and properties. In this review, we summarize and highlight the recent development of porous MOFs that are constructed from the multicarboxylate ligands containing m-benzenedicarboxylate moieties, and their promising applications in gas storage and separation, heterogeneous catalysis and luminescent sensing. This journal is © the Partner Organisations 2014.


Tantalum zirconium nitride films with different nitrogen concentrations were deposited by reactive co-sputtering. Systematical material characterization was done to study the effect of nitrogen concentration to the ternary nitride films' composition, microstructure, chemical and electrical properties. XRD and TEM showed that the microstructure of the films was mainly modulated by the Ta/Zr atomic ratio and nitrogen concentration, and amorphous structure formed in the nitrogen deficient films. XPS showed the chemical state of tantalum and zirconium atoms shifted systematically from metallic to ionic bonding state with the increasing of nitrogen. The stoichiometric ternary TaZrN films showed better conductivity than the binary TaN or ZrN constituents, because each tantalum atom contribute one excess d-orbital valence electron when the zirconium atom was substituted. © 2011 Elsevier Ltd and Techna Group S.r.l.


Li M.,Shantou University | Li D.,Shantou University | O'Keeffe M.,Arizona State University | O'Keeffe M.,KAIST | And 2 more authors.
Chemical Reviews | Year: 2014

A consistent approach to the description on the structures of metal-organic frameworks (MOFs) and related materials are studied in terms of their underlying nets for cases in which these nets have more than two kinds of vertices. For MOFs formed from polytopic linkers, identifying both the basic net in which the linker is considered as a single node and the derived net in which branch points are identified explicitly, is recommended. The intrinsic symmetry of the crystal is that of the derived net, which may be lower than that of the basic net. The net gwg, derived from cds, is an example in which a tetragonal basic net has only a monoclinic derived net of minimal transitivity. Structures with different derived nets that may have the same symmetry can be differentiated. The basic nets with transitivity 3 2 (type iv of section 7) are particularly important in this regard. Several MOFs have been constructed using an octatopic linker with symmetrical shapes.


Perrings C.,Arizona State University | Duraiappah A.,University of Bonn | Larigauderie A.,French Natural History Museum | Mooney H.,Stanford University
Science | Year: 2011

Assessments must provide conditional predictions of the consequences of specific policy options, at well-defined spatial and temporal scales.


Enders C.K.,Arizona State University
Rehabilitation Psychology | Year: 2011

Missing data methodology has improved dramatically in recent years, and popular computer programs now offer a variety of sophisticated options. Despite the widespread availability of theoretically justified methods, researchers in many disciplines still rely on subpar strategies that either eliminate incomplete cases or impute the missing scores with a single set of replacement values. This article provides readers with a nontechnical overview of some key issues from the missing data literature and demonstrates several of the techniques that methodologists currently recommend. This article begins by describing Rubin's missing data mechanisms. After a brief discussion of popular ad hoc approaches, the article provides a more detailed description of five analytic approaches that have received considerable attention in the missing data literature: maximum likelihood estimation, multiple imputation, the selection model, the shared parameter model, and the pattern mixture model. Finally, a series of data analysis examples illustrate the application of these methods. © 2011 American Psychological Association.


Gossard A.A.,Mayo Medical School | Lindor K.D.,Arizona State University
Journal of Gastroenterology | Year: 2012

Autoimmune hepatitis (AIH) is an inflammatory liver disease that predominantly affects females. The disease is characterized histologically by interface hepatitis, biochemically by increased aspartate and alanine aminotransferase levels, and serologically by the presence of autoantibodies and elevated levels of immunoglobulin G. AIH affects both adults and children, and is particularly aggressive in the latter group. It is a relatively rare but devastating disease, which progresses rapidly unless immunosuppressive treatment is started promptly. Treatment is often successful at inducing remission of disease, and this can lead to a normal life expectancy. However, progression to cirrhosis can and does occur in some. For those with advanced-stage disease and complications, consideration of liver transplantation is appropriate. © 2012 Springer.


Farin G.,Arizona State University
IEEE Transactions on Visualization and Computer Graphics | Year: 2012

We compare a variety of triangle shape measures using concepts such as smoothness and convexity. We show that one of these measures, the elongation measure, lends itself to an intuitive geometric interpretation. © 2012 IEEE.


Pyne S.J.,Arizona State University
Philosophical Transactions of the Royal Society B: Biological Sciences | Year: 2016

For most of human history, fire has been a pervasive presence in human life, and so also in human thought. This essay examines the ways in which fire has functioned intellectually in Western civilization as mythology, as religion, as natural philosophy and as modern science. The great phase change occurred with the development of industrial combustion; fire faded from quotidian life, which also removed it from the world of informing ideas. Beginning with the discovery of oxygen, fire as an organizing concept fragmented into various subdisciplines of natural science and forestry. The Anthropocene, however, may revive the intellectual role of fire as an informing idea or at least a narrative conceit. © 2016 The Author(s) Published by the Royal Society. All rights reserved.


While the important challenges of public deliberations on emerging technologies are crucial to keep in mind, this paper argues that scholars and practitioners have reason to be more confident in their performance of participatory technology assessments (pTA). Drawing on evidence from the 2008 National Citizens' Technology Forum (NCTF) conducted by the Center for Nanotechnology in Society at Arizona State University, this paper describes how pTA offers a combination of intensive and extensive qualities that are unique among modes of engagement. In the NCTF, this combination led to significant learning and opinion changes, based on what can be characterized as a high-quality deliberation. The quality of the anticipatory knowledge required to address emerging technologies is always contested, but pTAs can be designed with outcomes in mind-especially when learning is understood as an outcome. © 2011 Springer Science+Business Media B.V.


Mycobacterium tuberculosis is an extraordinarily successful human pathogen, infecting one-third of the world's population and causing nearly two million deaths each year. In this article, current trends in worldwide tuberculosis (TB) incidence, prevalence, and mortality are discussed along with standard TB treatment regimens, characteristics of first-line and second-line anti-tuberculosis drugs, and mechanisms of antibiotic resistance. The global TB emergency has been further exacerbated by extensively drug-resistant (XDR) TB strains that are resistant to our best antibiotics and very difficult to treat. This review also focuses on the emergence of XDR-TB strains, the global health impact, and existing treatment options and outcomes for XDR-TB disease. Finally, this review briefly describes new antituberculosis drugs currently in Phase II clinical evaluations and the impetus for discovering new antibacterial compounds to target drug-resistant M. tuberculosis and improve tuberculosis therapy. © by the authors.


Alvarez M.L.,Arizona State University | Cardineau G.A.,Monterrey Institute of Technology
Biotechnology Advances | Year: 2010

Yersinia pestis, the causative agent of bubonic and pneumonic plague, is an extremely virulent bacterium but there are currently no approved vaccines for protection against this organism. Plants represent an economical and safer alternative to fermentation-based expression systems for the production of therapeutic proteins. The recombinant plague vaccine candidates produced in plants are based on the two most immunogenic antigens of Y. pestis: the fraction-1 capsular antigen (F1) and the low calcium response virulent antigen (V) either in combination or as a fusion protein (F1-V). These antigens have been expressed in plants using all three known possible strategies: nuclear transformation, chloroplast transformation and plant-virus-based expression vectors. These plant-derived plague vaccine candidates were successfully tested in animal models using parenteral, oral, or prime/boost immunization regimens. This review focuses on the recent research accomplishments towards the development of safe and effective pneumonic and bubonic plague vaccines using plants as bioreactors. © 2009 Elsevier Inc. All rights reserved.


Bordner A.J.,Mayo Medical School | Mittelmann H.D.,Arizona State University
Molecular Biology and Evolution | Year: 2014

Despite the importance of a thermodynamically stable structure with a conserved fold for protein function, almost all evolutionary models neglect site-site correlations that arise from physical interactions between neighboring amino acid sites. This is mainly due to the difficulty in formulating a computationally tractable model since rate matrices can no longer be used. Here, we introduce a general framework, based on factor graphs, for constructing probabilistic models of protein evolution with site interdependence. Conveniently, efficient approximate inference algorithms, such as Belief Propagation, can be used to calculate likelihoods for these models. We fit an amino acid substitution model of this type that accounts for both solvent accessibility and site-site correlations. Comparisons of the new model with rate matrix models and alternative structure-dependent models demonstrate that it better fits the sequence data. We also examine evolution within a family of homohexameric enzymes and find that site-site correlations between most contacting subunits contribute to a higher likelihood. In addition, we show that the new substitution model has a similar mathematical form to the one introduced in Rodrigue et al. (Rodrigue N, Lartillot N, Bryant D, Philippe H. 2005. Site interdependence attributed to tertiary structure in amino acid sequence evolution. Gene 347:207-217), although with different parameter interpretations and values. We also perform a statistical analysis of the effects of amino acids at neighboring sites on substitution probabilities and find a significant perturbation of most probabilities, further supporting the significant role of site-site interactions in protein evolution and motivating the development of new evolutionary models similar to the one described here. Finally, we discuss possible extensions and applications of the new substitution model. © 2013 The Author 2013. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved.


Baranski M.R.,Arizona State University
Studies in History and Philosophy of Science Part C :Studies in History and Philosophy of Biological and Biomedical Sciences | Year: 2015

Indian wheat cultivation changed radically in the 1960s due to new technologies and policy reforms introduced during the Green Revolution, and farmers' adoption of 'packages' of modern seeds, fertilizer, and irrigation. Just prior to the Green Revolution, Indian scientists adopted a new plant breeding philosophy-that varieties should have as wide an adaptation as possible, meaning high and stable yields across different environments. But scientists also argued that wide adaptation could be achieved by selecting only plants that did well in high fertility and irrigated environments. Scientists claimed that widely adapted varieties still produce high yields in marginal areas. Many people have criticized the Green Revolution for its unequal spread of benefits, but none of these critiques address wide adaptation-the core tenant held by Indian agricultural scientists to justify their focus on highly productive land while ignoring marginal or rainfed agriculture. This paper also describes Norman Borlaug's and the Rockefeller Foundation's research program in wide adaptation, Borlaug's involvement in the Indian wheat program, and internal debates about wide adaptation and selection under ideal conditions among Indian scientists. It argues that scientists leveraged the concept of wide adaptation to justify a particular regime of research focused on high production agriculture. © 2015 Elsevier Ltd.


Tyler W.J.,Arizona State University
Neuroscientist | Year: 2011

Deep brain stimulation and vagal nerve stimulation are therapeutically effective in treating some neurological diseases and psychiatric disorders. Optogenetic-based neurostimulation approaches are capable of activating individual synapses and yield the highest spatial control over brain circuit activity. Both electrical and light-based neurostimulation methods require intrusive procedures such as surgical implantation of electrodes or photon-emitting devices. Transcranial magnetic stimulation has also shown therapeutic effectiveness and represents a recent paradigm shift towards implementing less invasive brain stimulation methods. Magnetic-based stimulation, however, has a limited focusing capacity and lacks brain penetration power. Because ultrasound can be noninvasively transmitted through the skull to targeted deep brain circuits, it may offer alternative approaches to currently employed neuromodulation techniques. Encouraging this idea, literature spanning more than half a century indicates that ultrasound can modulate neuronal activity. In order to provide a comprehensive overview of potential mechanisms underlying the actions of ultrasound on neuronal excitability, here, I propose the continuum mechanics hypothesis of ultrasonic neuromodulation in which ultrasound produces effects on viscoelastic neurons and their surrounding fluid environments to alter membrane conductance. While further studies are required to test this hypothesis, experimental data indicate ultrasound represents a promising platform for developing future therapeutic neuromodulation approaches. © The Author(s) 2011.


Dorn R.I.,Arizona State University
Geomorphology | Year: 2010

Debris flows debauch from tiny but steep mountain catchments throughout metropolitan Phoenix, Arizona, USA. Urban growth in the past half-decade has led to home construction directly underneath hundreds of debris-flow channels, but debris flows are not recognized as a potential hazard at present. One of the first steps in a hazard assessment is to determine occurrence rates. The north flank of the Ma Ha Tuak Range, just 10. km from downtown Phoenix, was selected to determine the feasibility of using the varnish microlaminations (VML) method to date every debris-flow levee from 127 catchment areas. Only 152 of the 780 debris-flow levees yielded VML ages in a first round of sampling; this high failure rate is due to erosion of VML by microcolonial fungi. The temporal pattern of preserved debris-flow levees indicates anomalously high production of debris flows at about 8.1. ka and about 2.8. ka, corresponding to Northern Hemisphere climatic anomalies. Because many prior debris flows are obliterated by newer events, the minimum overall occurrence rates of 1.3 debris flows per century for the last 60. ka, 2.2 flows/century for the latest Pleistocene, and 5 flows/century for the last 8.1. ka has little meaning in assessment of a contemporary hazard. This is because newer debris flows have obliterated an unknown number of past deposits. More meaningful to a hazards analysis is the estimate that 56 flows have occurred in the last 100. years on the north side of the range, an estimate that is consistent with direct observations of three small debris flows resulting events from a January 18-22, 2010 storm producing 70. mm of precipitation in the Ma Ha Tuak Range, and a 500. m long debris flow in a northern metropolitan Phoenix location that received over 150. mm of precipitation in this same storm. These findings support the need for a more extensive hazard assessment of debris flows in metropolitan Phoenix. © 2010 Elsevier B.V.


Ariaratnam S.T.,Arizona State University
Tunnelling and Underground Space Technology | Year: 2010

With a growing population and densely populated urban environments, China is looking at alternative methods of underground pipeline installation and replacement of their aging infrastructure. Conventional open trench activities result in disruption to these urban centers through road closures, traffic delays, traffic detours, loss of access to homes and business, unsightliness, noise and general disruption for everyone. Trenchless technologies are a viable and sustainable solution to China's buried infrastructure. Numerous challenges are present when promoting trenchless technologies in China including minimal local engineering knowledge, lack of trained contractors, lack of specifications, and system impact concerns raised by government owners. This paper presents the results of a survey questions obtained from a cross-section of 209 Chinese engineers from Shanghai, Beijing, Shengyang, Chongqing, and Guangzhou to gain a snapshot of the current level of knowledge on trenchless construction methods. The results reveal an understanding of trenchless technology in general; however, a lack of understanding of technologies such as lining of pipe, trenchless grouting, auger boring, and pipe bursting. Pipe jacking and horizontal directional drilling are currently by far the most recognized and understood trenchless technologies in China. © 2009 Elsevier Ltd.


Cacciatore J.,Arizona State University
Seminars in Fetal and Neonatal Medicine | Year: 2013

Despite the high prevalence globally, the death of a baby to stillbirth is an often misunderstood and disenfranchised loss. Mothers, fathers, and families struggle to cope with the immediate and long-lasting effects of a baby's death which can last for years and sometimes decades. In addition, providers can be adversely affected by stillbirth, particularly when met with experiential avoidance and a sense of guilt and failure. There is little evidence on intervention efficacy in acute grief following perinatal death; however, there is a growing body of scientific literature on the efficacy of mindfulness-based interventions in treating anxiety, depression, and other biopsychosocial maladies as well as improving patient satisfaction with psychosocial care. This paper explores one such intervention model, ATTEND (attunement, trust, therapeutic touch, egalitarianism, nuance, and death education), as a means to improve psychosocial care during both acute and chronic states of bereavement. Whereas the death of a baby to stillbirth is the ultimate paradox for providers and patients - the convergence of life and death and the fundamental contradiction it represents - with proper care and compassion, families stand a better chance in the face of such indescribable loss and they need not suffer alone. © 2012.


Casper M.J.,Arizona State University
Journal of health and social behavior | Year: 2010

In this selective review of the literature on medical sociology's engagement with technology, we outline the concurrent developments of the American Sociological Association section on medicine and advances in medical treatment. We then describe theoretical and epistemological issues with scholars' treatment of technology in medicine. Using symbolic interactionist concepts, as well as work from the interdisciplinary field of science and technology studies, we review and synthesize critical connections in and across sociology's intellectual relationship with medical technology. Next, we discuss key findings in these literatures, noting a shift from a focus on the effects of technology on practice to a reconfiguration of human bodies. We also look toward the future, focusing on connections between technoscientific identities and embodied health movements. Finally, we call for greater engagement by medical sociologists in studying medical technology and the process of policy-making--two areas central to debates in health economics and public policy.


Buman M.P.,Arizona State University
Journal of physical activity & health | Year: 2011

Using peer volunteers as delivery agents may improve translation of evidence-based physical activity promotion programs for older adults. This study examined whether tailored support from older peer volunteers could improve initiation and long-term maintenance of physical activity behavior. Participants were randomized to 2 16-week, group-based programs: (1) peer-delivered, theory-based support for physical activity behavior change; or (2) an intervention typically available in community settings (basic education, gym membership, and pedometer for self-monitoring), attention-matched with health education. Moderate-to-vigorous physical activity (MVPA) was assessed via daily self-report logs at baseline, at the end of the intervention (16 weeks), and at follow-up (18 months), with accelerometry validation (RT3) in a random subsample. Seven peer volunteers and 81 sedentary adults were recruited. Retention at the end of the trial was 85% and follow-up at 18 months was 61%. Using intent-to-treat analyses, at 16 weeks, both groups had similar significant improvements in MVPA. At 18 months, the group supplemented with peer support had significantly more MVPA. Trained peer volunteers may enhance long-term maintenance of physical activity gains from a community-based intervention. This approach has great potential to be adapted and delivered inexpensively in community settings.


Jiang N.,Arizona State University
Journal of Non-Crystalline Solids | Year: 2012

This work discussed the limitation of (scanning) transmission electron microscopy (TEM/STEM) techniques in quantitative measurements in electron-beam-sensitive silicate glasses and glass ceramics. Electron beam induced damages in the silicate glasses containing Na and the glass ceramics containing fluorite nanocrystals were demonstrated. The damages were mainly caused by preferentially removing Na and decomposing CaF2 into Ca. All the damage phenomena were observed under electron beam intensities, which were much weaker than the intensities used in the conventional high-resolution electron microscopy (HREM) and microanalysis in STEM. Therefore, although the advanced TEM/STEM techniques are very promising in the precise measurement of local composition at ultra-high spatial resolution in some materials, they may not be applicable to Na-containing silicate glasses and glass ceramics containing fluorite nanocrystals. © 2011 Elsevier B.V. All rights reserved.


Nishiura H.,University of Tokyo | Chowell G.,Arizona State University | Chowell G.,U.S. National Institutes of Health
Eurosurveillance | Year: 2014

The effective reproduction number, Rt, of Ebola virus disease was estimated using country-specific data reported from Guinea, Liberia and Sierra Leone to the World Health Organization from March to August, 2014. Rt for the three countries lies consistently above 1.0 since June 2014. Country-specific Rt for Liberia and Sierra Leone have lied between 1.0 and 2.0. Rt<2 indicate that control could be attained by preventing over half of the secondary transmissions per primary case. © 2014, European Centre for Disease Prevention and Control (ECDC). All rights reserved.


Hedrick P.W.,Arizona State University
Annals of Human Genetics | Year: 2011

α thalassemia is the result of the loss of one or both copies of the two human α globin genes. α thalassemia appears to be the most common monogenic disease in the world and is in high frequency where malaria is, or has been, endemic. In nonmalarial environments, α thalassemia is rare and its frequency can be explained by a balance of deletional mutation and purifying selection. In malarial environments, the loss of one or two copies of the four α globin genes in normal diploid genotypes confers resistance (lower mortality) to malaria. Fitness estimates from data from Kenyan and Papua New Guinea populations are used to predict the increase in the -α haplotype (with one deleted gene). The frequency of double deletions (-- haplotypes) is higher in some Asian populations than that of single deletions. In this case, heterozygotes with normal αα haplotypes are expected to have the highest fitness. Overall, this population genetic examination provides an evolutionary framework for understanding the worldwide frequency of α thalassemia and the deletions that cause it in both nonmalarial and malarial environments. © 2011 The Author Annals of Human Genetics © 2011 Blackwell Publishing Ltd/University College London.


Silk J.B.,Arizona State University | House B.R.,Max Planck Institute for Evolutionary Anthropology
Philosophical Transactions of the Royal Society B: Biological Sciences | Year: 2016

In this paper, we consider three hypotheses to account for the evolution of the extraordinary capacity for large-scale cooperation and altruistic social prefer- ences within human societies. One hypothesis is that human cooperation is built on the same evolutionary foundations as cooperation in other animal societies, and that fundamental elements of the social preferences that shape our species’ cooperative behaviour are also shared with other closely related primates. Another hypothesis is that selective pressures favouring cooperative breeding have shaped the capacity for cooperation and the development of social preferences, and produced a common set of behavioural dispositions and social preferences in cooperatively breeding primates and humans. The third hypothesis is that humans have evolved derived capacities for collabor- ation, group-level cooperation and altruistic social preferences that are linked to our capacity for culture. We draw on naturalistic data to assess differences in the form, scope and scale of cooperation between humans and other pri- mates, experimental data to evaluate the nature of social preferences across primate species, and comparative analyses to evaluate the evolutionary origins of cooperative breeding and related forms of behaviour. © 2016 The Author(s) Published by the Royal Society. All rights reserved.


Svoma B.M.,Arizona State University
International Journal of Climatology | Year: 2011

Trends in daily mountain snow levels over two key watersheds in central Arizona were established for the last 70 years. Snowfall levels were approximated using two methods: (1) an empirical method based on daily snowfall and precipitation data from an array of National Weather Service Cooperative (COOP) Network stations at a range of elevations, and (2) a theoretical method based on the calculation of the wet-bulb zero (WBZ) height using nearby rawindsonde atmospheric profile data. A trend towards a higher WBZ height since water year 1960 is evident, as is a highly significant trend in the percentage of days in which the snow level was above stations with elevations between 1095 and 2166 m since water year 1934. The two snow level variables are significantly positively related to air temperature. This could be problematic in a region where the population is dependent upon the efficiency of snow in generating runoff for replenishing ground and surface water supplies. Copyright © 2009 Royal Meteorological Society.


Herrmann M.,Arizona State University
Computers and Fluids | Year: 2013

This paper presents a novel model for the sub-filter surface tension induced motion of interfaces separating immiscible fluids. A key feature of the proposed Sub-Grid Surface Dynamics (SGSD) model is to take the sub-filter interface dynamics fully into account by employing a dual-scale approach. Instead of modeling the sub-filter interface geometry, it is resolved on an auxiliary grid using the Refined Level Set Grid approach. The required sub-filter velocity field on the auxiliary grid is reconstructed solving a PDE in a narrow band surrounding the interface. With the fully resolved interface geometry available, the previously unclosed surface tension term in the filtered Navier-Stokes equations can be directly closed using explicit filtering. The novel model shows excellent results for different test cases, including sub-grid oscillations of drops, the sub-grid Rayleigh-Plateau instability, and the viscous capillary breakup of a ligament. © 2013 Elsevier Ltd.


White M.D.,Arizona State University
Justice Quarterly | Year: 2014

Over the last two decades, New York City has witnessed historic drops in crime. Numerous explanations for this crime decline have been discussed, and the New York City Police Department (NYPD) has been central to that debate, most notably because of the adoption of order maintenance policing and the implementation of Compstat. While those developments in the early 1990s are clearly important for understanding the potential role of the NYPD in the crime decline, those changes did not occur in a vacuum. This paper adopts an historical framework that places the role of the NYPD in the crime decline in the larger context of the department's history, culture, and key events over a nearly 40-year span. This perspective suggests that many of the crime control strategies implemented by the NYPD over that time have been driven by internal and external crises, and that these strategies have also produced unintended consequences. With the historical analysis as a backdrop, the paper considers the ongoing debate over stop, question and frisk practices, and their disproportionate impact on minority residents, as the next potential crisis for the NYPD. The paper concludes with a discussion of the historical framework as a foundation for initiating a comparative dialog across law enforcement agencies regarding crime control strategies, their impact, and their consequences. © 2013 Academy of Criminal Justice Sciences.


The Crawford v. Washington decision has prompted changes in the way that intimate partner violence (IPV) is prosecuted. This research uses logistic regression to examine the victim, offender, and offense characteristics associated with the decision to prosecute a sample (N = 904) of domestic violence arrestees under an evidence-based prosecution strategy post-Crawford. Documentation of injury and police taking the perpetrator into custody at the scene of the crime have the greatest effect on the decision to prosecute, although the victim's willingness to assist with prosecution is also a significant factor. Future researchers should seek to replicate these findings, better understand current prosecution strategies, and determine the criminal justice and social service interventions best equipped to combat IPV in the post-Crawford era. © The Author(s) 2010.


Wallace D.,Arizona State University
Justice Quarterly | Year: 2014

Incarceration has been identified as a cause of poor health in current and formerly incarcerated individuals. Given the high likelihood of being in poor health when exiting prison, it is plausible that health impacts recidivism. Furthermore, ex-prisoners cluster in disadvantaged neighborhoods that are unlikely to have decent health services. Currently, there is insufficient research to examine this relationship at an ecological level. In this study, we investigate the relationship between the availability of health care organizations (HCOs) and their changes over time with neighborhood level recidivism, and how these relationships may be moderated by neighborhood disadvantage. We determine that the effect of HCOs on recidivism is indeed moderated through disadvantage: as disadvantage increases, the negative effect of losing significant amounts of HCOs on recidivism accelerates. Our results suggest that while increasing HCOs in disadvantaged neighborhoods is important, keeping HCOs in place is equally important for moderating negative neighborhood level outcomes. © 2012 © 2012 Academy of Criminal Justice Sciences.


Young J.T.N.,Arizona State University | Rebellon C.J.,University of New Hampshire | Barnes J.C.,University of Texas at Dallas | Weerman F.M.,Netherlands Institute for the Study of Crime and Law Enforcement NSCR
Criminology | Year: 2014

The strong correlation between measures of personal and peer deviance occurs with near "law-like" regularity. Yet, as with other manifestations of peer similarity (often referred to as homophily), the mechanisms generating this relationship are widely debated. Specific to the deviance literature, most studies have failed to examine, simultaneously, the degree to which similarity is the consequence of multiple causes. The current study addresses this gap by using longitudinal network data for 1,151 individuals from the Netherlands Institute for the Study of Crime and Law Enforcement (NSCR) School Project. Structural equation modeling is used to address these issues by adapting Jussim and Osgood's (1989) model of deviant attitudes in dyadic pairs to the current data. Across two separate behavioral domains (substance use and property offending), the results provide strong support for the prediction that individuals project their own deviant tendencies inaccurately onto their peers. Conversely, the results provide little or no support for the predictions that respondents accurately perceive their peers' deviance or that their perceptions of peer deviance influence their own behavior. Implications for understanding the role of peer behavior in the etiology of adolescent deviance are discussed. © 2013 American Society of Criminology.


Klitz W.,University of California at Berkeley | Hedrick P.,Arizona State University | Louis E.J.,University of Nottingham
Trends in Genetics | Year: 2012

Highly polymorphic exons of the major histocompatibility complex (MHC, or HLA in humans) encode critical amino acids that bind foreign peptides. Recognition of the peptide-MHC complexes by T cells initiates the adaptive immune response. The particular structure of these exons facilitates gene conversion(GC) events, leading to the generation of new alleles. Estimates for allele creation and loss indicate that more than 10. 000 such alleles are circulating at low frequencies in human populations. Empirical sampling has affirmed this expectation. This suggests that the MHC loci have a system for moving valuable and often complex variants into adaptive service. Here, we argue that HLA loci carry many new mutant alleles prepared to assume epidemiologically meaningful roles when called on by selection provoked by exposure to new and evolving pathogens. Because new mutant alleles appear in a population at the lowest possible frequency (i.e., a single copy), they have typically been thought of as having little consequence. However, this large population of rare yet potentially valuable new alleles may contribute to pathogen defense. © 2012 Elsevier Ltd.


Tran A.G.T.T.,Arizona State University
American Journal of Community Psychology | Year: 2014

Research on the mental health correlates of discrimination traditionally has been intra-individual, focusing exclusively on the individual directly experiencing discrimination. A small number of studies have begun to consider the links between parental experiences of discrimination and child mental health, but little is known about potential underlying mechanisms. The present study tested the independent mediating effects of parent mental health and household socioeconomic status on the associations between parental experiences of discrimination (past-year perceived discrimination and perceptions of being unaccepted culturally) and child mental health (internalizing and externalizing symptoms) using a bootstrapping analytic approach. Data were drawn from racial/ethnic minority (n = 383) and White (n = 574) samples surveyed in an urban Midwestern county. For all measures of discrimination and child mental health, findings supported an association between parental experiences of discrimination and child mental health. Whereas parent mental health served as a significant mediator in all analyses, socioeconomic status did not. Mediation findings held for both the White and racial/ethnic minority samples. Results suggest that parental experiences of discrimination and mental health may contribute to child mental health concerns, thus highlighting the role of family contexts in shaping child development. © 2013 Society for Community Research and Action.


MacKinnon D.P.,Arizona State University | Pirlott A.G.,University of Wisconsin - Eau Claire
Personality and Social Psychology Review | Year: 2015

Statistical mediation methods provide valuable information about underlying mediating psychological processes, but the ability to infer that the mediator variable causes the outcome variable is more complex than widely known. Researchers have recently emphasized how violating assumptions about confounder bias severely limits causal inference of the mediator to dependent variable relation. Our article describes and addresses these limitations by drawing on new statistical developments in causal mediation analysis. We first review the assumptions underlying causal inference and discuss three ways to examine the effects of confounder bias when assumptions are violated. We then describe four approaches to address the influence of confounding variables and enhance causal inference, including comprehensive structural equation models, instrumental variable methods, principal stratification, and inverse probability weighting. Our goal is to further the adoption of statistical methods to enhance causal inference in mediation studies. © 2014 by the Society for Personality and Social Psychology, Inc.


Ligon R.A.,Arizona State University
Behavioral Ecology and Sociobiology | Year: 2014

Research on intraspecific aggression has typically focused on dominant individuals, but a better understanding of the consequences and mechanisms of agonistic encounters requires a balanced perspective that includes knowledge of subordinate animal behaviors. In contrast to signals of fighting ability, signals of submission are an understudied component of agonistic communication that could provide important insights into the dynamics, function, and evolution of intraspecific competition. Here, I use a series of staged agonistic trials between adult male veiled chameleons Chamaeleo calyptratus to test the hypothesis that rapid skin darkening serves as a submissive signal to resolve agonistic activity. Concordant with this hypothesis, I found that losing chameleons darkened over the course of aggressive trials while winners brightened, and the likelihood of darkening increased when individuals were attacked more aggressively. Additionally, I found that the degree of brightness change exhibited by individual chameleons was tied to both overall and net aggression experienced during a trial, with chameleons who received high levels of aggression relative to their own aggression levels darkening to a greater extent than individuals receiving relatively less aggression. Lastly, I found that aggression increased for losers and winners prior to the onset of darkening by the eventual loser but that both chameleons reduced aggression after the losing chameleon began to darken. Based on the theoretical prediction that signals of submission should be favored when retreat options are restricted, I suggest that limited escapability imposed by chameleon morphology, physiology, and ecology favored the evolution of a pigment-based signal of submission in this group. © 2014 Springer-Verlag Berlin Heidelberg.


Hout M.C.,New Mexico State University | Goldinger S.D.,Arizona State University
Attention, Perception, and Psychophysics | Year: 2014

When people look for things in the environment, they use target templates—mental representations of the objects they are attempting to locate—to guide attention and to assess incoming visual input as potential targets. However, unlike laboratory participants, searchers in the real world rarely have perfect knowledge regarding the potential appearance of targets. In seven experiments, we examined how the precision of target templates affects the ability to conduct visual search. Specifically, we degraded template precision in two ways: 1) by contaminating searchers’ templates with inaccurate features, and 2) by introducing extraneous features to the template that were unhelpful. We recorded eye movements to allow inferences regarding the relative extents to which attentional guidance and decision-making are hindered by template imprecision. Our findings support a dual-function theory of the target template and highlight the importance of examining template precision in visual search. © 2014, The Psychonomic Society, Inc.


Redden R.,TRC Engineering and Consulting | Neithalath N.,Arizona State University
Cement and Concrete Composites | Year: 2014

Thermally assisted alkali activation of silica-rich glass powder to produce sustainable binders is investigated. Glass powder activated using NaOH provides higher compressive strengths than NaOH activated fly ash binders at lower heat curing temperatures. Sodium silicate gel is the reaction product when glass powder alone is used as the source material, while a combination of sodium silicate and sodium aluminosilicate (N-A-S-H) gels form in activated glass powder-fly ash blends. The activated glass powder-containing binders are found to disintegrate and lose strength when exposed to moisture or an alkaline solution, with the pure glass powder binders suffering the highest strength loss. Structural changes to the reaction product on exposure to moisture are explained using microstructural and FTIR spectroscopic observations. Doping the systems with Al containing (metakaolin) and Ca containing (slag) source materials, while retaining glass powder as the major component (50% or more), result in the formation of moisture-stable reaction products thereby mitigating the strength loss to a large extent. © 2013 Elsevier Ltd. All rights reserved.


Janssen M.A.,Arizona State University
Ecology and Society | Year: 2013

The structure and dynamics of ecosystems can affect the information available to resource users on the state of the common resource and the actions of other resource users. We present results from laboratory experiments that showed that the availability of information about the actions of other participants affected the level of cooperation. Since most participants in commons dilemmas can be classified as conditional cooperators, not having full information about the actions of others may affect their decisions. When participants had more information about others, there was a more rapid reduction of the resource in the first round of the experiment. When communication was allowed, limiting the information available made it harder to develop effective institutional arrangements. When communication was not allowed, there was a more rapid decline of performance in groups where information was limited. In sum, the results suggest that making information available to others can have an important impact on the conditional cooperation and the effectiveness of communication. © 2013 by the author(s).


Maienschein J.,Arizona State University
Developmental Biology | Year: 2011

Regenerative medicine is not new; it has not sprung anew out of stem cell science as has often been suggested. There is a rich history of study of regeneration, of development, and of the ways in which understanding regeneration advances study of development and also has practical and medical applications. This paper explores the history of regenerative medicine, starting especially with T.H. Morgan in 1901 and carrying through the history of transplantation research in the 20th century, to an emphasis on translational medicine in the late 20th century. © 2010 Elsevier Inc.


Brodsky S.J.,SLAC | Lebed R.F.,Arizona State University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015

We use the twist dimensions of the operators underlying the dynamical behavior of exclusive production processes as a tool for determining the structure of exotic heavy-quark states such as the Zc+(4430) tetraquark. The resulting counting rules predict distinctive falloffs of the cross sections in center-of-mass energy, thus distinguishing whether the tetraquarks are segregated into di-meson molecules, diquark-antidiquark pairs, or more democratically arranged four-quark states. In addition, we propose straightforward methods of experimentally producing additional exotic multiquark states. © 2015 American Physical Society.


Parikh M.,Arizona State University | Van Der Schaar J.P.,University of Amsterdam
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015

We derive the null energy condition, understood as a constraint on the Einstein-frame Ricci tensor, from world sheet string theory. For a closed bosonic string propagating in a curved geometry, the spacetime interpretation of the Virasoro constraint condition is precisely the null energy condition, to leading nontrivial order in the α′ expansion. Thus the deepest origin of the null energy condition lies in world sheet diffeomorphism invariance. © 2015 American Physical Society.


Lamm H.,Arizona State University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015

In contrast to other atomic systems, in true muonium (μ+μ-) the leading-order Z boson corrections to the hyperfine splitting are shown to be experimentally accessible in the near future. This contribution (-109MHz) constitutes a necessary contribution to a full O(mα7) calculation of the true muonium hyperfine splitting. This calculation would enable a number of possible solutions to the muon problem to be constrained. Additionally, we compute the general expression for a pseudovector coupling to particle-antiparticle bound states at leading order, including the annihilation channel. © 2015 American Physical Society.


This paper is written as a challenge to the ultrastable glass community to distinguish phenomenologically between the fast landscape searching scenario under discussion in the ultrastable glass community, and the alternative scenario in which the material in the ultrastable state is actually an attempted realization of the low temperature ideal glass phase of the system that can be reached in some systems, like ST2 water and amorphous silicon, and model systems like the attractive Jagla model, by a first order thermodynamic transition. These are special in that they exhibit first order phase transitions to the ground state that are accessible above the normal Tg of the high temperature phase - and in consequence exhibit vanishingly small excess entropies over crystal, and none of the "ubiquitous" glassy state cryogenic anomalies. In particular we show how, near a liquid-liquid critical point, the diffusivity can decrease arbitrarily rapidly over several orders of magnitude and that a growth front transformation from ultraslow phase to normal viscous liquid will be very difficult to distinguish from nucleation and growth of a new phase of different mobility. © 2014 Elsevier B.V. All rights reserved.


Furbish D.J.,Vanderbilt University | Schmeeckle M.W.,Arizona State University
Water Resources Research | Year: 2013

Particles transported as bed load within a specified streambed area possess a distribution of velocities. This distribution figures prominently in describing the rate of sediment transport and the rate of dispersal of particles during transport. We provide a probabilistic derivation of the distributions of streamwise and cross-stream particle velocities under uniform, quasi-steady transport conditions. The formulation centers on defining the ensemble of microstates of particle momenta (the set of possible ways to partition a fixed number of particles into momentum states) subject to the constraint that the sum of the particle momenta in each microstate is fixed, a constraint that is imposed by conditions of equilibrium transport. From this, we obtain the most probable distribution of momentum states, assuming each microstate within the ensemble is equally probable. The analysis suggests that, for small particle numbers, the distribution of velocities is exponential-like but decays faster than an exponential function. For large particle numbers, the distribution is exponential. These distributions are consistent with experimental results from high-speed imaging of sand particles transported as bed load over a planar bed, which reveal that the probability distributions of streamwise and cross-stream particle velocities are exponential-like. These particle velocity distributions also emerge from numerical analyses involving large eddy simulations of turbulent fluid motions and a discrete element method describing particle motions, wherein the large eddy simulations and discrete element method models are fully coupled in momentum. ©2013. American Geophysical Union. All Rights Reserved.


Lamm H.,Arizona State University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015

The leptonic bound states positronium and muonium are used to constrain Galileon contributions to the Lamb shift of muonic hydrogen. Through the application of a variety of bounds on lepton compositeness, it is shown that either the assumption of equating the charge radius of a particle with its Galileon scale radius is incompatible with experiments, or the scale of Galileons must be M>1.33GeV, too large to solve the muon problem. The possibility of stronger constraints in the future from true muonium is discussed. © 2015 American Physical Society. © 2015 American Physical Society.


Lebed R.F.,Arizona State University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015

The recent LHCb discovery of states Pc+(4380), Pc+(4450), believed to be cc¯uud pentaquark resonances, begs the question of whether equivalent states with cc¯→ss¯ exist, and how they might be produced. The precise analogue to the Pc+ discovery channel Λb→J/ψK-p, namely, Λc→φπ0p, is feasible for this study and indeed is less Cabibbo suppressed, although its limited phase space suggests that evidence of a ss¯uud resonance Ps+ would be confined to the kinematic end-point region. © 2015 American Physical Society.


Lebed R.F.,Arizona State University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015

Observed enhancements in the forward and backward directions for φ-meson photoproduction off nucleons are shown to be explainable by the production of a nonresonant recoiling (su) diquark, (s¯ud) triquark pair. We show that the necessity of maintaining approximate collinearity of the quarks within these units constrains configurations with the minimum momentum transfer, and hence maximal amplitudes, to lie preferentially along the reaction axis. © 2015 American Physical Society.


Gray W.J.,Lawrence Livermore National Laboratory | Scannapieco E.,Arizona State University
Astrophysical Journal | Year: 2013

Intergalactic filaments form the foundation of the cosmic web that connect galaxies together, and provide an important reservoir of gas for galaxy growth and accretion. Here we present very high resolution two-dimensional simulations of the thermal and chemical evolution of such filaments, making use of a 32 species chemistry network that tracks the evolution of key molecules formed from hydrogen, oxygen, and carbon. We study the evolution of filaments over a wide range of parameters including the initial density, initial temperature, strength of the dissociating UV background, and metallicity. In low-redshift, Z ≈ 0.1 Z⊙ filaments, the evolution is determined completely by the initial cooling time. If this is sufficiently short, the center of the filament always collapses to form a dense, cold core containing a substantial fraction of molecules. In high-redshift, Z = 10-3 Z⊙ filaments, the collapse proceeds much more slowly. This is mostly due to the lower initial temperatures, which lead to a much more modest increase in density before the atomic cooling limit is reached, making subsequent molecular cooling much less efficient. Finally, we study how the gravitational potential from a nearby dwarf galaxy affects the collapse of the filament and compare this to NGC 5253, a nearby starbursting dwarf galaxy thought to be fueled by the accretion of filament gas. In contrast to our fiducial case, a substantial density peak forms at the center of the potential. This peak evolves faster than the rest of the filament due to the increased rate at which chemical species form and cooling occurs. We find that we achieve similar accretion rates as NGC 5253 but our two-dimensional simulations do not recover the formation of the giant molecular clouds that are seen in radio observations. © 2013. The American Astronomical Society. All rights reserved.


Rhoads J.E.,Arizona State University
Astrophysical Journal | Year: 2010

The luminosities of short-duration gamma-ray burst (SGRB) host galaxies appear to be anticorrelated with both the isotropic equivalent gamma-ray energy and the gamma-ray luminosity of the explosions, based on a sample of 12 bursts with host galaxy redshifts and photometry. The correlation does depend on the correct identification of the GRB 050509b host, but is otherwise robust. In particular, simple observational selection effects only strengthen the statistical significance of this correlation, from ∼95% to ∼99%. The correlation may indicate that there are two physically distinct groups of SGRBs. If so, it requires that the more luminous class of explosions be associated with the younger class of progenitors. Alternatively, it could be due to a continuous distribution of burst and host properties, in which case it could be used as a crude SGRB distance indicator. As one possible explanation, we find that the effect of binary neutron star masses on inspiral time and energy reservoir produces a correlation of the appropriate sign, but does not automatically reproduce the correlation slope or the full range of SGRB energy scales. If confirmed by larger samples, this correlation will provide a valuable new constraint on SGRB progenitor models. © 2010. The American Astronomical Society. All rights reserved.


This study examined relations between perceived racial discrimination, multiracial identity integration (i.e., racial distance and racial conflict), and psychological adjustment (i.e., distress symptoms, positive affect, and negative affect) of 263 multiracial adults, using an online cross-sectional survey design. As hypothesized, higher levels of perceived racial discrimination was related to lower levels of psychological adjustment (i.e., higher distress symptoms and negative affect). Also, higher levels of multiracial identity integration with low racial conflict was related to higher levels of psychological adjustment (i.e., lower distress symptoms and negative affect), whereas higher levels of multiracial identity integration with low racial distance was related to higher levels of psychological adjustment (i.e., lower negative affect). Finally, multiracial identity integration (i.e., lower racial conflict) moderated the relationship between perceived racial discrimination and psychological adjustment (i.e., negative affect) with results suggesting multiracial identity integration related to low racial conflict buffers the negative effects of perceived racial discrimination on psychological adjustment. Findings from this study are discussed in terms of future research on the psychological well-being of multiracial individuals and implications for clinical practice with multiracial adults.


Croucher M.,Arizona State University
Energy Policy | Year: 2011

We discuss that whilst energy conservation and energy efficiency both ultimately have the same goal they attempt to achieve this via very different approaches. We then discuss how both options face significant barriers to ultimately successfully reduce electricity consumption. © 2011.


Westerhoff P.,Arizona State University | Nowack B.,Empa - Swiss Federal Laboratories for Materials Science and Technology
Accounts of Chemical Research | Year: 2013

Engineered nanomaterials (ENMs) are a new class of environmental pollutants. Researchers are beginning to debate whether new modeling paradigms and experimental tests to obtain model parameters are required for ENMs or if approaches for existing pollutants are robust enough to predict ENM distribution between environmental compartments.This Account outlines how experimental research can yield quantitative data for use in ENM fate and exposure models. We first review experimental testing approaches that are employed with ENMs. Then we compare and contrast ENMs against other pollutants. Finally, we summarize the findings and identify research needs that may yield global descriptors for ENMs that are suitable for use in fate and transport modeling.Over the past decade, researchers have made significant progress in understanding factors that influence the fate and transport of ENMs. In some cases, researchers have developed approaches toward global descriptor models (experimental, conceptual, and quantitative). We suggest the following global descriptors for ENMs: octanol-water partition coefficients, solid-water partition coefficients, attachment coefficients, and rate constants describing reactions such as dissolution, sedimentation, and degradation. ENMs appear to accumulate at the octanol-water interface and readily interact with other interfaces, such as lipid-water interfaces. Batch experiments to investigate factors that influence retention of ENMs on solid phases are very promising. However, ENMs probably do not behave in the same way as dissolved chemicals, and therefore, researchers need to use measurement techniques and concepts more commonly associated with colloids. Despite several years of research with ENMs in column studies, available summaries tend to discuss the effects of ionic strength, pH, organic matter, ENM type, packing media, or other parameters qualitatively rather than reporting quantitative values, such as attachment efficiencies, that would facilitate comparison across studies. Only a few structure-activity relationships have been developed for ENMs so far, but such evaluations will facilitate the understanding of the reactivities of different forms of a single ENM.The establishment of predictive capabilities for ENMs in the environment would enable accurate exposure assessments that would assist in ENM risk management. Such information is also critical for understanding the ultimate disposition of ENMs and may provide a framework for improved engineering of nanomaterials that are more environmentally benign. © 2012 American Chemical Society.


Amdam G.V.,Arizona State University | Amdam G.V.,Norwegian University of Life Sciences
Aging Cell | Year: 2011

Positive social contact is an important factor in healthy aging, but our understanding of how social interactions influence senescence is incomplete. As life expectancy continues to increase because of reduced death rates among elderly, the beneficial role of social relationships is emerging as a cross-cutting theme in research on aging and healthspan. There is a need to improve knowledge on how behavior shapes, and is shaped by, the social environment, as well as needs to identify and study biological mechanisms that can translate differences in the social aspects of behavioral efforts, relationships, and stress reactivity (the general physiological and behavioral response-pattern to harmful, dangerous or unpleasant situations) into variation in aging. Honey bees (Apis mellifera) provide a genetic model in sociobiology, behavioral neuroscience, and gerontology that is uniquely sensitive to social exchange. Different behavioral contact between these social insects can shorten or extend lifespan more than 10-fold, and some aspects of their senescence are reversed by social cues that trigger aged individuals to express youthful repertoires of behavior. Here, I summarize how variation in social interactions contributes to this plasticity of aging and explain how beneficial and detrimental roles of social relationships can be traced from environmental and biological effects on honey bee physiology and behavior, to the expression of recovery-related plasticity, stress reactivity, and survival during old age. This system provides intriguing opportunities for research on aging. © 2010 The Author. Aging Cell © 2010 Blackwell Publishing Ltd/Anatomical Society of Great Britain and Ireland.


Pasqualetti M.J.,Arizona State University
Annals of the Association of American Geographers | Year: 2011

Although wind power is local, sustainable, affordable, and carbon free, mounting public opposition to the landscape changes it produces threatens its expansion. In an era when many countries are looking to renewable energy as an answer to questions about national security and the risks of climate change, it is important to explain the sources of this reaction. This article looks for similarities in public resistance to wind developments in four diverse settings: Palm Springs, California; Cape Cod, Massachusetts; the Isle of Lewis, Scotland; and Oaxaca State, Mexico. Despite the natural and cultural diversity among these places, there are five common threads in the opposition that has been experienced: immobility, the site specificity of the resource; immutability, an expectation of landscape permanence; solidarity, the close relationship between people and the land; imposition, a sense of marginalization; and place identity, a loss of security. Considering more deeply the relationship between land and life, in advance of the development of renewable energy resources, will help smooth the otherwise bumpy road toward a more sustainable future. © 2011 by Association of American Geographers Initial submission, March 2010.


Imam M.H.,University of North Dakota | Lindor K.D.,Arizona State University
Seminars in Liver Disease | Year: 2014

Our understanding of the natural history of primary biliary cirrhosis (PBC) has been evolving especially following the introduction of ursodeoxycholic acid (UDCA). A clearer understanding of disease pathophysiology and earlier diagnosis with increased prevalence of the disease worldwide has led to increased interest and improved outcomes in patients with PBC. In this article, the authors touch briefly on features of the disease and describe the natural history of PBC prior to and after the introduction of UDCA. Copyright © 2014 by Thieme Medical Publishers, Inc.


Lebed R.F.,Arizona State University
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2015

Starting with the dynamical picture of the exotic cc--containing states XYZ as the confinement-induced hadronization of a rapidly separating pair of a compact diquark and antidiquark, we describe the pentaquark candidates Pc +(4380) and Pc +(4450) in terms of a confined but rapidly separating color-antitriplet diquark cu and color-triplet "triquark" c-(ud). This separation explains the relatively small Pc + widths, despite these 5-quark systems lying far above both the J/ψ p and Λc D-(*)0 thresholds. The Pc + states are predicted to form isospin doublets with neutral partners Pc 0. © 2015 The Author.


Brewis A.A.,Arizona State University
Social Science and Medicine | Year: 2014

Even as obesity rates reach new highs, the social stigmatization of obesity seems to be strengthening and globalizing. This review identifies at least four mechanisms by which a pervasive environment of fat stigma could reinforce high body weights or promote weight gain, ultimately driving population-level obesity. These are direct effects through behavior change because of feeling judged, and indirect effects of social network changes based on stigmatizing actions and decisions by others, psychosocial stress from feeling stigmatized, and the structural effects of discrimination. Importantly, women and children appear especially vulnerable to these mechanisms. The broader model provides an improved basis to investigate the role of stigma in driving the etiology of obesity, and explicates how individual, interpersonal, and structural dimensions of stigma are connected to variation in health outcomes, including across generations. © 2014 Elsevier Ltd.


Franklin J.,Arizona State University
Diversity and Distributions | Year: 2010

Aim: To demonstrate that multi-modelling methods have effectively been used to combine static species distribution models (SDM), predicting the geographical pattern of suitable habitat, with dynamic landscape and population models to forecast the impacts of environmental change on species' status, an important goal of conservation biogeography. Methods: Three approaches were considered: (1) incorporating models of species migration to understand the ability of a species to occupy suitable habitat in new locations; (2) linking models of landscape disturbance and succession to models of habitat suitability; and (3) fully linking models of habitat suitability, habitat dynamics and spatially explicit population dynamics. Results: Linking species-environment relationships, landscape dynamics and population dynamics in a multi-modelling framework allows the combined impacts of climate change (affecting species distribution and vital rates) and land cover dynamics (land use change, altered disturbance regimes) on species to be predicted. This approach is only feasible if the life history parameters and habitat requirements of the species are well understood. Main conclusions: Forecasts of the impacts of global change on species may be improved by considering multiple causes. A range of methods are available to address the interactions of changing habitat suitability, habitat dynamics and population response that vary in their complexity, realism and data requirements. © 2010 Blackwell Publishing Ltd.


Silveira M.G.,Case Western Reserve University | Lindor K.D.,Arizona State University
Expert Opinion on Pharmacotherapy | Year: 2014

Introduction: Primary biliary cirrhosis (PBC) is a chronic cholestatic liver disease of adults. Treatments are needed when patients have incomplete response to ursodeoxycholic acid (UDCA). Areas covered: Discoveries of the key role played by bile acids (BAs) and nuclear receptors (NRs) in regulating liver and metabolic homeostasis have led to promising therapeutic approaches in liver diseases. A PubMed search for the recent literature on NRs in liver disease was conducted. In particular, obeticholic acid (OCA) is a farnesoid X receptor (FXR) agonist that has an important role in the enterohepatic circulation of BAs. Preliminary studies of OCA in patients with PBC have demonstrated marked biochemical improvement when administered in combination with UDCA and alone. Pruritus is the most common side effect, limiting treatment at higher doses. Budesonide is a glucocorticoid receptor/pregnane X receptor (PXR) agonist also involved in BA synthesis, metabolism and transport. Studies with budesonide have shown positive effects of short-term combination therapy in selected patients with early stage disease and overlapping features of autoimmune hepatitis. Expert opinion: Though larger studies are needed, preliminary results of agents targeting FXR and PXR have been encouraging, particularly in subsets of patients with PBC and may mark a new therapeutic era. © 2014 Informa UK, Ltd.


Turner II B.L.,Arizona State University
Land Use Policy | Year: 2010

Consistent with the challenges of sustainability science, land architecture offers a comprehensive approach to land system dynamics useful for numerous types of assessments, ranging from the vulnerability of coupled human-environment systems to forest transitions. With antecedents in several research communities, land architecture addresses the tradeoffs within and between the human and environmental subsystems of land systems in terms of the kind, magnitude, and pattern of land uses and covers. This approach is especially cogent for changes in tropical forests, given the broad-ranging forces acting on them and the equally broad-ranging consequences of their loss. The rudiments of the land architecture approach are illustrated for changes in seasonal tropical forests in the southern Yucatán of Mexico, the pivot of which is the Calakmul biosphere reserve. Simplifying the dynamics involved, the region-wide land architecture is the collective design of stakeholders with different land-use goals that favor tradeoffs in subsystem outcomes serving better either the reserve and related programs or the smallholder farmers that populate the region. A major tradeoff involves forest cover per se, which holds implications for forest transition theory. Evidence for an incipient transition involves the scale of analysis taken. The dynamics involved hold too much uncertainty to forecast a permanent transition to more forest cover and imply that more complex but robust versions of the theory are required. © 2009 Elsevier Ltd. All rights reserved.


Fernando H.J.S.,Arizona State University | Fernando H.J.S.,University of Notre Dame
Annual Review of Fluid Mechanics | Year: 2010

A majority of the world's urban centers are located in complex terrain, in which local airflow patterns are driven by pressure gradients and thermal forcing, while being strongly influenced by topographic effects and human (anthropogenic) activities. A paradigm in this context is a city located in a valley surrounded by mountains, slopes, and escarpments, in which the airflow is determined by terrain-induced perturbations to synoptic (background) flow, mesoscale thermal circulation (valley/slope flows) generated by local heating or cooling, and by their interaction with factitious (e.g., buildings and roads) and natural (e.g., vegetation and terrain) elements. The dynamics of airflows intrinsic to urban areas in complex terrain is reviewed here by employing idealized flow configurations to illustrate fundamental processes. Urban flows span a wide range of space and time scales and the emphasis here is on mesoscales (1-100 km). Basic fluid dynamics plays a central role in explaining observations of urban flow and in developing subgrid parameterizations for predictive models. Copyright © 2010 by Annual Reviews. All rights reserved.


Glenberg A.M.,Arizona State University | Glenberg A.M.,University of Wisconsin - Madison | Gallese V.,University of Parma | Gallese V.,Italian Institute of Technology
Cortex | Year: 2012

Evolution and the brain have done a marvelous job solving many tricky problems in action control, including problems of learning, hierarchical control over serial behavior, continuous recalibration, and fluency in the face of slow feedback. Given that evolution tends to be conservative, it should not be surprising that these solutions are exploited to solve other tricky problems, such as the design of a communication system. We propose that a mechanism of motor control, paired controller/predictor models, has been exploited for language learning, comprehension, and production. Our account addresses the development of grammatical regularities and perspective, as well as how linguistic symbols become meaningful through grounding in perception, action, and emotional systems. © 2011 Elsevier Srl.


Schoville B.J.,Arizona State University
Journal of Human Evolution | Year: 2010

Unretouched convergent flakes are frequently a well represented tool type in many Middle Stone Age (MSA) assemblages. Damage to the lateral margins of these points is frequent; however, analytical methods for dealing with the frequency and distribution of edge damage on points have not been developed and applied to a complete MSA lithic assemblage. A method for using GIS to quantify edge damage and statistically analyze the relative location and frequency of edge damage is presented here and applied to the complete assemblage of MSA points from Pinnacle Point Cave 13B (PP13B), South Africa. The results indicate a frequency of edge damage consistent with heavier utilization of the dorsal surface over the ventral surface, and the left side over the right, with the dorsal left lateral margin being most heavily damaged. Additionally, the distribution of edge damage and low frequency of impact damage to the points suggest that PP13B represents a location where points were used for cutting activities and discarded. Applying the recording procedures advocated here to controlled edge damage replication experiments will help provide the interpretive linkages to site assemblage edge damage distributions. © 2010 Elsevier Ltd.


Silk J.,Arizona State University
Current Biology | Year: 2016

Individuals that participate in exchanges with delayed rewards can be exploited if their partners don't reciprocate. In humans, friendships are built on trust, and trust enhances cooperation. New evidence suggests that close social bonds also enhance trust in chimpanzees. © 2016 Elsevier Ltd.


Pfluger H.-J.,Free University of Berlin | Duch C.,Arizona State University
Physiology | Year: 2011

Skeletal muscle innervation differs between vertebrates and insects. Insect muscle fibers exhibit graded electrical potentials and are innervated by excitatory, inhibitory, and also neuromodulatory motoneurons. The latter form a unique class of unpaired neurons with bilaterally symmetrical axons that release octopamine to alter the efficacy of synaptic transmission and regulate muscle energy metabolism by activating glycolysis. Octopaminergic neurons that innervate muscles with a high energy demand, for example, flight muscles that move the wings of a locust up and down, are active during rest but are inhibited during flight and its preparatory phase, a jump. Therefore, it is argued that these neurons are involved in providing locusts with the necessary fuel at takeoff, but then may aid the switch to lipid oxidation during flight. In general, the octopaminergic system may switch the whole organism from a tonic to a dynamic state. 2011 Int. Union Physiol. Sci./Am. Physiol. Soc.


Scannapieco E.,Arizona State University
Astrophysical Journal Letters | Year: 2013

The interstellar medium is a multiphase gas in which turbulent support is as important as thermal pressure. Sustaining this configuration requires both continuous turbulent stirring and continuous radiative cooling to match the decay of turbulent energy. While this equilibrium can persist for small turbulent velocities, if the one-dimensional velocity dispersion is larger than ≈35 km s-1, the gas moves into an unstable regime that leads to rapid heating. I study the implications of this turbulent runaway, showing that it causes a hot gas outflow to form in all galaxies with a gas surface density above ≈50 M pc-2, corresponding to a star formation rate per unit area of ≈0.1 M yr-1 kpc-2. For galaxies with v esc ≳ 200 km s-1, the sonic point of this hot outflow should lie interior to the region containing cold gas and stars, while for galaxies with smaller escape velocities, the sonic point should lie outside this region. This leads to efficient cold cloud acceleration in higher mass galaxies, while in lower mass galaxies, clouds may be ejected by random turbulent motions rather than accelerated by the wind. Finally, I show that energy balance cannot be achieved at all for turbulent media above a surface density of ≈105 M pc-2. © 2013. The American Astronomical Society. All rights reserved.


Cahill T.M.,Arizona State University
Atmospheric Environment | Year: 2013

Studies of size-resolved organic speciation of aerosols are still relatively rare and are generally only conducted over short durations. However, size-resolved organic data can both suggest possible sources of the aerosols and identify the human exposure to the chemicals since different aerosol sizes have different lung capture efficiencies. The objective of this study was to conduct size-resolved organic aerosol speciation for a calendar year in Phoenix, Arizona to determine the seasonal variations in both chemical concentrations and size profiles. The results showed large seasonal differences in combustion pollutants where the highest concentrations were observed in winter. Summertime aerosols have a greater proportion of biological compounds (e.g. sugars and fatty acids) and the biological compounds represent the largest fraction of the organic compounds detected. These results suggest that standard organic carbon (OC) measurements might be heavily influenced by primary biological compounds particularly if the samples are PM10 and TSP samples. Several large dust storms did not significantly alter the organic aerosol profile since Phoenix resides in a dusty desert environment, so the soil and plant tracer of trehalose was almost always present. The aerosol size profiles showed that PAHs were generally most abundant in the smallest aerosol size fractions, which are most likely to be captured by the lung, while the biological compounds were almost exclusively found in the coarse size fraction. © 2013 Elsevier Ltd.


Schmeeckle M.W.,Arizona State University
Journal of Geophysical Research: Earth Surface | Year: 2014

A model of sand transport in water is produced by combining a turbulence-resolving large eddy simulation (LES) with a discrete element model (DEM) prescribing the motion of individual grains of medium sand. The momentum effect of each particle on the fluid is calculated at the LES cell containing the particle, and the fluid velocity and pressure, interpolated to each particle center, is used to derive fluid force on each particle in the DEM. Eleven numerical experiments are conducted of an initially flat bed of particles. The experiments span a range of motion, from essentially no motion to vigorous suspension. Hydraulic roughness is found to increase abruptly at the transition from bed load to suspended load transport. Suspended sediment extracts momentum from the flow and decreases the rate of shear. Whereas, slightly higher in the flow, vertical drag by suspended grains damps turbulence and increases the rate of shear. Vertical sediment diffusivity and effective particle settling velocity are much smaller than is commonly assumed in suspended sediment models. The bed load experiments suggest that saltation by itself is a poor model of bed load sand transport. In contrast to expectations from saltation models, the peak bed load flux occurs at essentially the same level as the bed, and grains move slowly in frequent contact with other grains. Higher- and faster-moving bed load grains that can be considered to be in saltation represent a smaller portion of the total flux. Entrainment of bed load grains occurs in response to fluid penetration of the bed by high-vorticity turbulence structures embedded within broader high speed fluid regions referred to as a sweeps or high-speed wedges. ©2014. American Geophysical Union. All Rights Reserved.


Randall A.K.,Arizona State University | Schoebi D.,University of Fribourg
Emotion | Year: 2015

Symptoms of psychological distress are associated with the experience of heightened negative affect, and the inability to successfully regulate one's emotions. Romantic partners can, however, influence and regulate each other's emotional experiences, especially during times of distress. Using daily diary measures taken 4 times per day over a 10-day period, we examined whether susceptibility to partner affect was associated with levels and trajectories of psychological distress over 12 months. Results from both partners of 103 committed relationships (206 individuals) found that men and women showed decreased levels of distress over the year when they were more susceptible to their partner's positive affect, but the degree of susceptibility varied with respect to negative affect. Examining susceptibility to partner affect may be a valuable complementary approach to studying relational contributions to the social regulation of emotions, especially in understanding the progression of psychological distress. © 2015 American Psychological Association.


I present a general mathematical modeling framework that can provide a foundation for the study of sustainability in social- ecological systems (SESs). Using basic principles from feedback control and a sequence of specific models from bioeconomics and economic growth, I outline several mathematical and empirical challenges associated with the study of sustainability of SESs. These challenges are categorized into three classes: (1) the social choice of performance measures, (2) uncertainty, and (3) collective action. Finally, I present some opportunities for combining stylized dynamical systems models with empirical data on human behavior and biophysical systems to address practical challenges for the design of effective governance regimes (policy feedbacks) for highly uncertain natural resource systems. © 2014, Society for Mathematical Biology.


Wang Z.-H.,Arizona State University
Journal of Hydrology | Year: 2012

Soil field experiments usually consist of measurements of soil temperatures, heat fluxes and soil water contents. Accurate determination of the soil thermal field, in particular, prediction of the soil surface temperature and the ground heat, contains the signature to the surface energy partitioning, and is therefore critical to the surface energy balance closure problem. In this paper, we develop a numerical procedure to reconstruct the entire soil thermal field from a single depth measurement of either temperature or heat flux. The new algorithm is based on Green's function approach by using the fundamental solution of heat conduction in semi-infinite soils and Duhamel's integral for incorporation of general boundary conditions. It is highlighted that the new approach is capable of accurately reproducing results of some existing numerical approaches, with a more general setting and treatment of the heat diffusion problem, and hence provides a possible unified framework for the estimation of thermal field in soils. © 2012 Elsevier B.V.


Bodansky D.,Arizona State University
Climatic Change | Year: 2013

The potential of geoengineering to reverse global warming rapidly and cheaply makes it alluring to groups across the political spectrum. But geoengineering also poses significant risks and raises the specter of technology gone awry. This article analyzes the basic governance issues raised by geoengineering, including the possible functions, forms, objects and agents of governance. It then explores these issues by focusing on four scenarios of particular concern: inadequate research funding, premature rejection, unilateral individual action, and unilateral state action. © 2013 Springer Science+Business Media Dordrecht.


Wallace D.,Arizona State University
Crime and Delinquency | Year: 2015

“Neighborhood disorder” refers to how people perceive neighborhoods as unsafe and disorganized. However, certain disorder cues may indicate disorder to some residents but not to others. There are many explanations for disorder perception bias, though few have been tested. This article uses data on 4,721 residents in 100 neighborhoods in Seattle to assess two explanations for biases: neighborhood attachment and routine activities. Using fixed-effect models, this article shows that neighborhood attachment and routine activities provide additional insight into disorder perceptions. Hanging out with teens and engaging in protective neighborhood activities, like watching neighbors’ property, have a strong positive influence on disorder perceptions. This study concludes by discussing alternative explanations for disorder perception bias and their impact on disorder theory as a whole. © 2011 SAGE Publications


Carter C.R.,Arizona State University
Journal of Supply Chain Management | Year: 2011

This essay introduces a forum that discusses the conceptual theory development approach within the context of the supply chain management discipline. The purpose of the forum is to provide guidance to both authors and reviewers concerning how to carry out meaningful and impactful conceptual theory development research. In this essay I discuss the conceptual theory development approach, describe the Journal of Supply Chain Management's perspective and philosophy toward conceptual theory development, offer broad guidelines to aid authors in crafting their work and reviewers in effectively evaluating and helping authors to further develop their manuscripts, and introduce the remaining essays that comprise the discussion forum. © 2011 Institute for Supply Management, Inc.™.


Van Ryzin M.J.,University of Oregon | Dishion T.J.,Arizona State University
Journal of Child Psychology and Psychiatry and Allied Disciplines | Year: 2013

Background: Aggression is one of the more stable characteristics of child and adolescent development, and violent behavior in early adulthood is often foreshadowed by aggressive behavior in childhood and early adolescence. Considerable evidence has linked coercive family interactions to aggressive behavior in childhood, but less research has been conducted on the joint role of family and peer interaction in the escalation of aggression to violence in adulthood. Methods: We coded family interactions at age 12-13 and friendship interaction at age 16-17 in a multiethnic sample of youth and families. Violence in young adulthood (age 22-23) was measured using self-report, criminal records, and parent report. We tested the hypothesis that a process of 'coercive joining' in friendship interactions mediated the relationship between coercive family interactions and serious violence. Results: We found that observed coercive joining in friendships at age 16-17 predicted early-adulthood violent behavior over and above an established tendency toward antisocial behavior. We also found that observed coercive family interactions at age 12 predicted early-adulthood violence, and that coercive joining with friends fully mediated this link. Conclusions: These results significantly extend coercion theory by suggesting that coercive joining in the context of peer groups is an additional mechanism by which coercive processes in the family are extended and amplified to violent behavior in early adulthood. Our findings suggest the importance of addressing both individual interpersonal skills and self-organizing peer groups when intervening to prevent violent behavior. © 2012 The Authors.


Bradley R.H.,Arizona State University | Corwyn R.,University of Arkansas at Little Rock
Journal of Abnormal Child Psychology | Year: 2013

This study used data from the NICHD Study of Early Child Care and Youth Development to examine relations between parenting, self-control and externalizing behavior from early childhood to mid-adolescence (N = 956; 49.9 % male). Results indicated that maternal sensitivity, parental harshness and productive activity are related to externalizing problems but that patterns of relations change from early childhood to middle childhood to adolescence, with evidence suggesting that externalizing behavior influences parenting more than the reverse from middle childhood onward. Self-control measured during early adolescence partially mediated relations between maternal sensitivity and adolescent-reported externalizing behavior. Parental monitoring during adolescence was also related to externalizing behavior at age 15. Monitoring partially mediated the relation between externalizing behavior in early adolescence and externalizing at age 15. © 2012 Springer Science+Business Media New York.


Matyushov D.V.,Arizona State University
Journal of Physical Chemistry Letters | Year: 2012

Theories of activated transitions traditionally separate the dynamics and statistics of the thermal bath in the reaction rate into the preexponential frequency factor for the dynamics and a Boltzmann factor for the statistics. When the reaction rate is comparable to relaxation frequencies of the medium, the statistics loses ergodicity and the activation barrier becomes dependent on the medium dynamics. This scenario is realized for mixed-valence self-exchange electron transfer at temperatures near the point of solvent crystallization. These complexes, studied by Kubiak and coworkers, display anti-Arrhenius temperature dependence on lowering temperature when approaching crystallization; that is, the reaction rate increases nonlinearly in Arrhenius coordinates. Accordingly, the solvent relaxation slows down following a power temperature law. With this functional form for the relaxation time, nonergodic reaction kinetics accounts well for the observations. © 2012 American Chemical Society.


Smith B.,Arizona State University
Language Learning and Technology | Year: 2012

This study investigated whether eye-tracking technology could be employed as a measure of noticing of corrective feedback (in the form of explicit recasts) during NS-NNS task-based synchronous computer-mediated communication (SCMC). Pairs of university-level learners of English (n = 18) engaged in a short chat interaction task with a native speaker, who provided intensive and explicit corrective recasts. Participants' eye gaze record was compared to that from a stimulated recall. Noticing events (increased visual attention) were compiled and compared from each technique to determine whether these two techniques yielded similar data. Noticing events from each technique were also compared to results of immediate and delayed post tests of the targeted items. Results confirm the strength of both measures as methods for measuring what learners notice in the corrective feedback during SCMC. Further, the eye tracking and stimulated recall data also suggest that although learners engage in similar amounts of viewing activity across recasts targeting various linguistic categories, they are able to notice semantic and syntactic targets more easily than morphological targets. Results are discussed in terms of eye tracking as a potentially valuable tool in exploring the nature of noticing in instructed SLA and also in terms of argued benefits of CMC for language learning. © 2012.


Weierstall U.,Arizona State University
Philosophical Transactions of the Royal Society B: Biological Sciences | Year: 2014

X-ray free-electron lasers overcome the problem of radiation damage in protein crystallography and allow structure determination from micro- and nanocrystals at room temperature. To ensure that consecutive X-ray pulses do not probe previously exposed crystals, the sample needs to be replaced with the X-ray repetition rate, which ranges from 120 Hz at warm linacbased free-electron lasers to 1 MHz at superconducting linacs. Liquid injectors are therefore an essential part of a serial femtosecond crystallography experiment at an X-ray free-electron laser. Here, we compare different techniques of injecting microcrystals in solution into the pulsed X-ray beam in vacuum. Sample waste due to mismatch of the liquid flow rate to the X-ray repetition rate can be addressed through various techniques. © 2014 The Author(s) Published by the Royal Society. All rights reserved.


Belitsky A.V.,Arizona State University
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2012

Maximal helicity-violating scattering amplitudes in N= 4 supersymmetric Yang-Mills theory are dual to Wilson loops on closed null polygons. We perform their operator product expansion analysis in two-dimensional kinematics in the soft-collinear approximation which corresponds to the case when some light-cone distances vanish. We construct the expansion in terms of multi-particle "heavy"-light operators, where the "heavy" fields are identified with the Wilson lines defining the OPE channel and the light fields emerge from the curvature of the contour. The correlation function of these define the remainder function. We study the dilatation operator for these operators at one-loop order and find that it corresponds to a non-compact open spin chain. This provides an alternative view on elementary excitations propagating on the GKP string at weak coupling, which now correspond to particles traveling along an open spin chain. The factorized structure of the Wilson loop in the soft limit allows one to represent the two-loop correction to the octagon Wilson loop as a convolution formula and find the corresponding remainder function. © 2012 Elsevier B.V.


Roth S.H.,Arizona State University
Drugs | Year: 2012

Despite well known complications, oral nonsteroidal anti-inflammatory drugs (NSAIDs) remain the most commonly prescribed medications in the US for musculoskeletal disorders such as osteoarthritis. Although there has been a recent focus on the cardiovascular and renal complications associated with these agents, NSAID gastropathy continues to be a particular concern in many patients, especially those at increased risk for serious adverse events, including the elderly. Complicating the diagnosis of NSAID gastropathy is its silent course, which, up to half of the time, is asymptomatic. Several strategies are currently employed by physicians to mitigate the risk of serious gastrointestinal events. These include either addition of a proton pump inhibitor to current nonselective NSAID therapy or the use of a cyclo-oxygenase-2-selective NSAID. Although these agents are effective at mitigating the overall risk of gastrointestinal adverse events, they fail to address NSAID-related cardiovascular and renal risks. Due to their reduced systemic absorption, topical NSAIDs may present a viable option for patients at increased risk for serious NSAID-related adverse events, including gastropathy. © 2012 Springer International Publishing AG. All rights reserved.


Belitsky A.V.,Arizona State University
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2012

We explore the duality between supersymmetric Wilson loop on null polygonal contours in maximally supersymmetric Yang-Mills theory and next-to-maximal helicity violating (NMHV) scattering amplitudes. Earlier analyses demonstrated that the use of a dimensional regulator for ultraviolet divergences, induced due to presence of the cusps on the loop, yields anomalies that break both conformal symmetry and supersymmetry. At one-loop order, these are present only in Grassmann components localized in the vicinity of a single cusp and result in a universal function for any number of sites of the polygon that can be subtracted away in a systematic manner leaving a well-defined supersymmetric remainder dual to corresponding components of the superamplitude. The question remains though whether components which were free from the aforementioned supersymmetric anomaly at leading order of perturbation theory remain so once computed at higher orders. Presently we verify this fact by calculating a particular component of the null polygonal super Wilson loop at two loops restricting the contour kinematics to a two-dimensional subspace. This allows one to perform all computations in a concise analytical form and trace the pattern of cancellations between individual Feynman graphs in a transparent fashion. As a consequence of our consideration we obtain a dual conformally invariant result for the remainder function in agreement with one-loop NMHV amplitudes. © 2012.


Yan T.,Wayne State University | Dooley K.J.,Arizona State University
Journal of Operations Management | Year: 2013

Manufacturers involve suppliers in new product development in order to access knowledge and resources, but these benefits only occur with effective project-level integration. Adopting a contingency theory view, we develop hypotheses concerning how two integrative devices, intensive communication and congruent goals, influence project performance under various conditions of uncertainty. We test our theoretical model with a sample of 214 buyer-supplier joint new product development projects. Results suggest that communication intensity is positively associated with project performance when either task or relational uncertainty is high, but is also negatively associated with performance when task uncertainty is low. Goal congruence is positively associated with project performance, especially when either task uncertainty is low or relational uncertainty is high. We discuss the implications of these findings for theory and practice. © 2013 Elsevier B.V.


Borkowski L.B.,Arizona State University
Computers, Materials and Continua | Year: 2013

The microstructural variation in fiber-reinforced composites has a direct relationship with its local and global mechanical performance. When micromechanical modeling techniques for unidirectional composites assume a uniform and periodic arrangement of fibers, the bounds and validity of this assumption must be quantified. The goal of this research is to quantify the influence of microstructural randomness on effective homogeneous response and local inelastic behavior. The results indicate that microstructural progression from ordered to disordered decreases the tensile modulus by 5%, increases the shear modulus by 10%, and substantially increases the magnitude of local inelastic fields. The experimental and numerical analyses presented in this paper show the importance of microstructural variability when small length scale phenomena drive global response. Copyright © 2013 Tech Science Press.


Chaput J.C.,Arizona State University
Chembiochem : a European journal of chemical biology | Year: 2014

Recent advances in synthetic biology have made it possible to replicate an unnatural base pair in living cells. This study highlights the technologies developed to create a semisynthetic organism with an expanded genetic alphabet and the potential challenges of moving forward. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Hadeler K.P.,Arizona State University
Journal of Mathematical Biology | Year: 2012

A multitype pair formation model for a one-sex population, without separation, with given type distribution of singles, produces a distribution of pairs with the given type distribution as a marginal distribution. The pair distribution can be seen as a nonnegative symmetric matrix. For this matrix representation formulas have been given years ago and have been widely used. The goal of the paper is to understand these formulas in probabilistic terms and give a meaning to their coefficients. Our approach connects the formulas to the problem of completing a substochastic matrix to a stochastic matrix. In this way the coefficients in the representation formula can be interpreted as preferences and insight can be gained into the set of distributions respecting given preferences. In order to put these questions into a wider perspective, the classical two-sex pair formation models are reviewed and embedded into the class of one-sex models, and dynamic models are designed that yield pair distributions as limit elements. © 2011 Springer-Verlag.


Pittmana A.,Arizona State University
Journal of Speech, Language, and Hearing Research | Year: 2011

Purpose: To determine the rate of word learning for children with hearing loss (HL) in quiet and in noise compared to normalhearing (NH) peers. The effects of digital noise reduction (DNR) were examined for children with HL. Method: Forty-one children with NH and 26 children with HL were grouped by age (8-9 years and 11-12 years). The children learned novel words associated with novel objects through a process of trial and error. Functions relating performance across trials were calculated for each child in each listening condition and were compared. Results: Significant effects were observed for age (older > younger) in the children with NH and listening condition (quiet > noise) in the children with HL. Significant effects of hearing status were also observed across groups (NH > HL), indicating that the children with HL required more trials to learn the new words. However, word learning improved significantly in noise with the use of DNR for the older but not for the younger children with HL. Hearing aid history and signal-to-noise ratio did not contribute to performance. Conclusion: Word learning was significantly reduced in younger children, in noise, and in the presence of hearing loss. Age-related benefits of DNR were apparent for children over 10 years of age. © American Speech-Language-Hearing Association.


Rez P.,Arizona State University
Microscopy and Microanalysis | Year: 2014

The recently developed in-column monochromators make it possible to record energy-c spectra with resolutions better than 30 meV from nanometer-sized regions. It should therefore in principle be possible to detect localized vibrational excitations. The scattering geometry in the electron microscope means that bond stretching in the specimen plane or longitudinal optic phonons dominate the scattering. Most promising for initial studies are vibrations with energies between 300 and 400 meV from hydrogen bonded to other atoms. Estimates of the scattering cross-sections on the basis of a simple model show that they are about the same as inner shell scattering cross-sections. Cross-sections also increase with charge transfer between the atoms, and theory incorporating realistic charge distributions shows that signal/noise is the only limitation to high-resolution imaging. Given the magnitude of the scattering cross-sections, minimizing the tail of the zero-loss peak is just as important as achieving a small-width at half-maximum. Improvements in both resolution and controlling the zero-loss tail will be necessary before it is practical to detect optic phonons in solids between 40 and 60 meV. Copyright © 2014 Microscopy Society of America.


Chen X.,Arizona State University | Huang J.,Chinese University of Hong Kong
IEEE Journal on Selected Areas in Communications | Year: 2013

Efficient distributed spectrum sharing mechanism is crucial for improving the spectrum utilization. The spatial aspect of spectrum sharing, however, is less understood than many other aspects. In this paper, we generalize a recently proposed spatial congestion game framework to design efficient distributed spectrum access mechanisms with spatial reuse. We first propose a spatial channel selection game to model the distributed channel selection problem with fixed user locations. We show that the game is a potential game, and develop a distributed learning mechanism that converges to a Nash equilibrium only based on users' local observations. We then formulate the joint channel and location selection problem as a spatial channel selection and mobility game, and show that it is also a potential game. We next propose a distributed strategic mobility algorithm, jointly with the distributed learning mechanism, that can converge to a Nash equilibrium. © 1983-2012 IEEE.


Manninen B.A.,Arizona State University
American Journal of Bioethics | Year: 2010

In 2008, many states sought to pass Human Life Amendments, which would extend the definition of personhood to encompass newly fertilized eggs. If such an amendment were to pass, Roe v. Wade, as currently defended by the Supreme Court, may be repealed. Consequently, it is necessary to defend the right to an abortion in a manner that succeeds even if a Human Life Amendment successfully passes. J.J. Thomson's argument in "A Defense of Abortion" successfully achieves this. Her argument is especially strong when one considers that her central thesis-that one person's right to life does not entail the right to use another's person's body for continued sustenance-is pervasive in legal policies in the U.S.A. © Taylor & Francis Group, LLC.


Pommier A.,Arizona State University
Surveys in Geophysics | Year: 2014

Magnetotelluric (MT) surveying is a remote sensing technique of the crust and mantle based on electrical conductivity that provides constraints to our knowledge of the structure and composition of the Earth's interior. This paper presents a review of electrical measurements in the laboratory applied to the understanding of MT profiles. In particular, the purpose of such a review is to make the laboratory technique accessible to geophysicists by pointing out the main caveats regarding a careful use of laboratory data to interpret electromagnetic profiles. First, this paper addresses the main issues of cross-spatial-scale comparisons. For brevity, these issues are restricted to reproducing in the laboratory the texture, structure of the sample as well as conditions prevailing in the Earth's interior (pressure, temperature, redox conditions, time). Second, some critical scientific questions that have motivated laboratory-based interpretation of electromagnetic profiles are presented. This section will focus on the characterization of the presence and distribution of hydrogen in the Earth's crust and mantle, the investigation of electrical anisotropy in the asthenosphere and the interpretation of highly conductive field anomalies. In a last section, the current and future challenges to improve quantitative interpretation of MT profiles are discussed. These challenges correspond to technical improvements in the laboratory and the field as well as the integration of other disciplines, such as petrology, rheology and seismology. © 2013 Springer Science+Business Media Dordrecht.


Janssen M.A.,Arizona State University
Current Opinion in Environmental Sustainability | Year: 2015

During the last 40 years evidence from systematic case study analysis and behavioral experiments have provided a comprehensive perspective on how communities can manage common resources in a sustainable way. The conventional theory based on selfish rational actors cannot explain empirical observations. A more comprehensive theoretical framework of human behavior is emerging that include concepts such as trust, conditional cooperation, other-regarding preferences, social norms, and reputation. The new behavioral perspective also demonstrates that behavioral responses depend on social and biophysical context. © 2014 Elsevier B.V.


McConnell E.D.,Arizona State University
Housing Policy Debate | Year: 2012

Housing affordability in the United States is generally operationalized using the ratio approach, with those allocating more than thirty percent of income to shelter costs considered to have housing affordability challenges. Alternative standards have been developed that focus on residual income, whether income remaining after housing expenditures is sufficient to meet non-housing needs. This study employs Los Angeles Family and Neighborhood Survey data to consider racial/ethnic, nativity and legal status differences in one residual income standard. Logistic regression analyses of housing-induced poverty focus on whether there are differences among five distinct groups: US born Latinos, Non-Hispanic Whites, and African Americans, authorized Latino immigrants, and unauthorized Latino immigrants. Results suggest that: (1) Latino natives are significantly more likely to be in housing-induced poverty than African Americans and Latino immigrants, and (2) unauthorized Latino immigrants are not more likely to experience the outcome than other groups. The present work extends previous research. First, the results provide additional evidence of the value of operationalizing housing affordability using a residual income standard. Alternatives to the ratio approach deserve more empirical attention from a wider range of scholars and policymakers interested in housing affordability. Second, housing scholarship to date generally differentiates among Latinos by ethnicity, nativity, and citizenship. The present study contributes to emerging research investigating heterogeneity among Latinos by nativity and legal status. © 2011 Virginia Polytechnic Institute and State University.


Five years after Katrina's devastation, almost 90 per cent of New Orleans metropolitan population has returned. Recovery patterns, however, remain highly uneven. This paper examines the relationship between pre-existing demographic and housing conditions, damage from Hurricane Katrina, access to federal individual and housing assistance, and repopulation rates in the New Orleans metropolitan area. Findings shed light on the respective roles of pre-existing conditions, damage and assistance in shaping long-term recovery outcomes. In the case of Katrina, areas that have experienced the lowest repopulation rates had high levels of damage and received disproportionately low individual and housing assistance relative to damage. These areas are characterised by higher concentrations of minorities, low-income households and rental units than areas that experienced higher repopulation rates. Findings also highlight structural causes for the unevenness of recovery outcomes. The paper concludes with suggestions for a more effective and sustainable post-disaster assistance and recovery approach. © 2012 Urban Studies Journal Limited.


Mohacsy H.,Arizona State University
Journal of Combinatorial Theory. Series A | Year: 2011

This paper gives the answer to a question of R.M. Wilson regarding the existence of group divisible designs of large order. Let k and u be positive integers such that 2≤k≤u. Then there exists an integer m0≤m0(k,u) such that there exists a group divisible design of group type mu with block size k and index one for any integer m≥m0 satisfying the necessary arithmetic conditions. 1. m(u-1)≡0mod(k-1), 2. m2u(u-1)≡0modk(k-1).This paper also presents a large-index asymptotic existence theorem for group divisible t-designs with a fixed number of groups, fixed group size and fixed block size. © 2011 Elsevier Inc.


Cacciatore J.,Arizona State University
Clinical Obstetrics and Gynecology | Year: 2010

Evidence-based practice and patient-centered practice are not mutually exclusive clinical ideals. Instead, both styles hold tremendous potential for complementarity in healthcare and should be used to enhance clinical relationships in which caring is humble, mindful, and nuanced. The onus of the responsibility for many decisions about care after stillbirth falls on clinical staff. Yet, even in the dearth of literature exploring standards of care during stillbirth the results can be conflicting. Thus, research in both patient-centered and evidence-based approaches suggest that less emphasis should be placed on the standardization of care; rather, the focus should be on relational caregiving that underscores the uniqueness of each patient and their family, recognizes culture, and encourages affirmative, rather than traumatizing, provider reactions. © 2010, Lippincott Williams & Wilkins.


Nijhout H.F.,Duke University | Callier V.,Arizona State University
Annual Review of Entomology | Year: 2015

The developmental mechanisms that control body size and the relative sizes of body parts are today best understood in insects. Size is controlled by the mechanisms that cause growth to stop when a size characteristic of the species has been achieved. This requires the mechanisms to assess size and respond by stopping the process that controls growth. Growth is controlled by two hormones, insulin and ecdysone, that act synergistically by controlling cell growth and cell division. Ecdysone has two distinct functions: At low concentration it controls growth, and at high levels it causes molting and tissue differentiation. Growth is stopped by the pulse of ecdysone that initiates the metamorphic molt. Body size is sensed by either stretch receptors or oxygen restriction, depending on the species, which stimulate the high level of ecdysone secretion that induces a molt. Wing growth occurs mostly after the body has stopped growing. Wing size is adjusted to body size by variation in both the duration and level of ecdysone secretion. © 2015 by Annual Reviews. All rights reserved.


Belitsky A.V.,Arizona State University
Nuclear Physics B | Year: 2015

We address the near-collinear expansion of multiparticle NMHV amplitudes, namely, the heptagon and octagons in the dual language of null polygonal super Wilson loops. In particular, we verify multiparticle factorization of charged pentagon transitions in terms of pentagons for single flux-tube excitations within the framework of refined operator product expansion. We find a perfect agreement with available tree and one-loop data. © 2015 The Author.


Belitsky A.V.,Arizona State University
Nuclear Physics B | Year: 2015

Scattering amplitudes in maximally supersymmetric gauge theory receive a dual description in terms of the expectation value of the super Wilson loop stretched on a null polygonal contour. This makes the analysis amenable to nonperturbative techniques. Presently, we elaborate on a refined form of the operator product expansion in terms of pentagon transitions to compute twist-two contributions to NMHV amplitudes. To start with, we provide a novel derivation of scattering matrices starting from Baxter equations for flux-tube excitations propagating on magnon background. We propose bootstrap equations obeyed by pentagon form factors with nonsinglet quantum numbers with respect to the R-symmetry group and provide solutions to them to all orders in 't Hooft coupling. These are then successfully confronted against available perturbative calculations for NMHV amplitudes to four-loop order. © 2015 The Author.


Belitsky A.V.,Arizona State University
Nuclear Physics B | Year: 2015

We analyze the near-collinear limit of the null polygonal hexagon super Wilson loop in the planar N=4 super-Yang-Mills theory. We focus on its Grassmann components which are dual to next-to-maximal helicity-violating (NMHV) scattering amplitudes. The kinematics in question is studied within a framework of the operator product expansion that encodes propagation of excitations on the background of the color flux tube stretched between the sides of Wilson loop contour. While their dispersion relation is known to all orders in 't Hooft coupling from previous studies, we find their form factor couplings to the Wilson loop. This is done making use of a particular tessellation of the loop where pentagon transitions play a fundamental role. Being interested in NMHV amplitudes, the corresponding building blocks carry a nontrivial charge under the SU(4) R-symmetry group. Restricting the current consideration to twist-two accuracy, we analyze two-particle contributions with a fermion as one of the constituents in the pair. We demonstrate that these nonsinglet pentagons obey bootstrap equations that possess consistent solutions for any value of the coupling constant. To confirm the correctness of these predictions, we calculate their contribution to the super Wilson loop demonstrating agreement with recent results to four-loop order in 't Hooft coupling. © 2015 The Author.


Angell A.,Arizona State University
Nature Materials | Year: 2012

Ken-ichiro Murata and Hajime Tanaka have found the evidence of a transition between two coexisting liquids of the same composition in a water-glycerol mixture, where glycerol prevents the crystallization of water, provides a unique link to an elusive liquid-liquid transition in pure water. Detailed microscopy experiments conducted in Tanaka's laboratory at different temperatures have shown that, just as in the common case of near-critical liquid-gas transitions and liquid-liquid transitions, the transition process can occur by either the discrete mechanism of nucleation and growth, or uniform spinodal decomposition. Their work represents a distinctive approach to the elusive LLT in pure water, if the transition is indeed isocompositional. The authors have also deduced that the transition is isocompositional from the observation that ice crystals eventually form in the residual liquid, defined as the low-density liquid that forms at low temperature.


Poste G.,Arizona State University
Trends in Molecular Medicine | Year: 2012

Knowledge of the altered molecular landscapes in disease offers great promise for developing biomarker-based tests to improve diagnosis and optimize treatment. Progress in biomarker research has been frustratingly slow due to the poor clinical trial design and the lack of standards for specimen collection, biomarker analysis, and data reporting. The ability of high throughput genomics, proteomics, and other 'omics' platforms to profile a large number of analytes in a single assay, together with the pending prospect of rapid expansion of whole exome and whole genome sequencing for clinical use, is increasing the technical and logistical complexity of biomarker validation. Harnessing these new technologies and improved productivity in biomarker validation will depend on adopting systems-based approaches and require major changes in the organization and funding strategies for biomarker research. A systems approach will require new multi-institution collaborations, the integration of diverse technical and clinical activities, greater engagement of industry, and education of regulators, clinicians, and payers about how to use biomarkers for improved patient management and clinical outcomes. © 2012 Elsevier Ltd.


Dounskaia N.,Arizona State University
Exercise and Sport Sciences Reviews | Year: 2010

The leading joint hypothesis (LJH) offers a novel interpretation of control of human movements that involve multiple joints. The LJH makes control of each multijoint movement transparent. This review highlights effective applications of the LJH to learning of new motor skills and to analysis of movement changes caused by aging and motor disorders. Copyright © 2010 by the American College of Sports Medicine.


Van Horn W.D.,Arizona State University
Critical Reviews in Biochemistry and Molecular Biology | Year: 2013

Human vitamin K epoxide reductase (hVKOR) is a small integral membrane protein involved in recycling vitamin K. hVKOR produces vitamin K hydroquinone, a crucial cofactor for γ-glutamyl carboxylation of vitamin K dependent proteins, which are necessary for blood coagulation. Because of this, hVKOR is the target of a common anticoagulant, warfarin. Spurred by the identification of the hVKOR gene less than a decade ago, there have been a number of new insights related to this protein. Nonetheless, there are a number of key issues that have not been resolved; such as where warfarin binds hVKOR, or if human VKOR shares the topology of the structurally characterized but distantly related prokaryotic VKOR. The pharmacogenetics and single nucleotide polymorphisms of hVKOR used in personalized medicine strategies for warfarin dosing should be carefully considered to inform the debate. The biochemical and cell biological evidence suggests that hVKOR has a distinct fold from its ancestral protein, though the controversy will likely remain until structural studies of hVKOR are accomplished. Resolving these issues should impact development of new anticoagulants. The paralogous human protein, VKOR-like1 (VKORL1) was recently shown to also participate in vitamin K recycling. VKORL1 was also recently characterized and assigned a functional role as a housekeeping protein involved in redox homeostasis and oxidative stress with a potential role in cancer regulation. As the physiological interplay between these two human paralogs emerge, the impacts could be significant in a number of diverse fields from coagulation to cancer. © 2013 Informa Healthcare USA, Inc.


Yuan Y.,University of Texas M. D. Anderson Cancer Center | MacKinnon D.P.,Arizona State University
Psychological Methods | Year: 2014

Mediation analysis has many applications in psychology and the social sciences. The most prevalent methods typically assume that the error distribution is normal and homoscedastic. However, this assumption may rarely be met in practice, which can affect the validity of the mediation analysis. To address this problem, we propose robust mediation analysis based on median regression. Our approach is robust to various departures from the assumption of homoscedasticity and normality, including heavy-tailed, skewed, contaminated, and heteroscedastic distributions. Simulation studies show that under these circumstances, the proposed method is more efficient and powerful than standard mediation analysis. We further extend the proposed robust method to multilevel mediation analysis, and demonstrate through simulation studies that the new approach outperforms the standard multilevel mediation analysis. We illustrate the proposed method using data from a program designed to increase reemployment and enhance mental health of job seekers. © 2013 American Psychological Association.


Vollan B.,University of Mannheim | Ostrom E.,Indiana University Bloomington | Ostrom E.,Arizona State University
Science | Year: 2010

In Ethiopia, groups with a higher propensity to cooperate avoid the tragedy of the commons.


Barrera Jr. M.,Arizona State University
Journal of consulting and clinical psychology | Year: 2013

To reduce health disparities, behavioral health interventions must reach subcultural groups and demonstrate effectiveness in improving their health behaviors and outcomes. One approach to developing such health interventions is to culturally adapt original evidence-based interventions. The goals of the article are to (a) describe consensus on the stages involved in developing cultural adaptations, (b) identify common elements in cultural adaptations, (c) examine evidence on the effectiveness of culturally enhanced interventions for various health conditions, and (d) pose questions for future research. Influential literature from the past decade was examined to identify points of consensus. There is agreement that cultural adaptation can be organized into 5 stages: information gathering, preliminary design, preliminary testing, refinement, and final trial. With few exceptions, reviews of several health conditions (e.g., AIDS, asthma, diabetes) concluded that culturally enhanced interventions are more effective in improving health outcomes than usual care or other control conditions. Progress has been made in establishing methods for conducting cultural adaptations and providing evidence of their effectiveness. Future research should include evaluations of cultural adaptations developed in stages, tests to determine the effectiveness of cultural adaptations relative to the original versions, and studies that advance our understanding of cultural constructs' contributions to intervention engagement and efficacy.


Ainsworth B.E.,Arizona State University
Journal of physical activity & health | Year: 2012

Assessment of physical activity using self-report has the potential for measurement error that can lead to incorrect inferences about physical activity behaviors and bias study results. To provide recommendations to improve the accuracy of physical activity derived from self report. We provide an overview of presentations and a compilation of perspectives shared by the authors of this paper and workgroup members. We identified a conceptual framework for reducing errors using physical activity self-report questionnaires. The framework identifies 6 steps to reduce error: 1) identifying the need to measure physical activity, 2) selecting an instrument, 3) collecting data, 4) analyzing data, 5) developing a summary score, and 6) interpreting data. Underlying the first 4 steps are behavioral parameters of type, intensity, frequency, and duration of physical activities performed, activity domains, and the location where activities are performed. We identified ways to reduce measurement error at each step and made recommendations for practitioners, researchers, and organizational units to reduce error in questionnaire assessment of physical activity. Self-report measures of physical activity have a prominent role in research and practice settings. Measurement error may be reduced by applying the framework discussed in this paper.


Gasparini N.M.,Tulane University | Whipple K.X.,Arizona State University
Lithosphere | Year: 2014

High relief and steep rainfall gradients make the eastern flank of the northern Bolivian Andes an excellent location for deciphering the relative roles of tectonics and climate on erosion and landscape evolution. We seek to resolve the climate versus tectonics debate in this location by linking topographic analyses and erosion rate data with fluvial bedrock incision theory and numerical landscape evolution modeling. We find that patterns in the channel steepness index (channel slope normalized for drainage area) in both transverse channels that drain across the rainfall gradient through the driest and wettest parts of the landscapes, and frontal channels that drain only the wettest regions are indicative primarily of a gradient in rock uplift rate, although climate likely plays a secondary role in shaping these channel profiles. Previously published erosion rates from 23 watersheds vary with the proposed rock uplift gradient and inversely with rainfall rate, suggesting that increased rainfall is not driving increased rock uplift and erosion. The channel steepness index in an additional 35 tributary watersheds increases with the proposed rock uplift gradient. Simulations from a landscape evolution model that isolate the signatures of rainfall and uplift patterns on landscape morphology corroborate our interpretation that the morphology of this landscape is primarily controlled by a gradient in rock uplift rate, with rainfall rates playing a secondary role. Model results also suggest that the differences between channel steepness values in the transverse and frontal channels cannot be explained by the uplift and rainfall patterns alone. Differences in lithology may be contributing to the higher channel steepness values in the transverse channels, or the transverse channels may be affected by a transient oversteepening phenomenon seen in tools-and-cover river incision models. The conclusions are possible only after detailed comparisons among real and modeled rivers of different sizes that drain different locations. We present best practices for future studies that seek to resolve the relative imprint of rock uplift and rainfall on a landscape. © 2014 Geological Society of America.


Pommier A.,Arizona State University
Earth, Planets and Space | Year: 2014

By enhancing mass transfer and energy release, the cycle of volatiles and melt is a major component of subduction. Investigating this fluid cycle is therefore critical to understand the past and current activity of subduction zones. Fluids can significantly affect rock electrical conductivity and elastic parameters that are measured using electromagnetic and seismic methods, respectively. This letter emphasizes how these geophysical methods complement each other to provide information about the storage of fluids in subduction systems. By compiling electromagnetic and seismic results from various subduction zones, a possible correlation between electrical conductivity and seismic wave attenuation anomalies in the mantle wedge is observed, consistent with fluid accumulation. A possible relationship between geophysical properties and the slab age is also suggested, whereas no significant trend is observed between electrical conductivity or seismic wave attenuation and estimates of water flux in the mantle wedge. These field-based relationships require further constrains, emphasizing the need for new measurements in the laboratory. © 2014 Pommier; licensee Springer.


Loladze I.,University of Nebraska - Lincoln | Elser J.J.,Arizona State University
Ecology Letters | Year: 2011

One of the most intriguing patterns in the biosphere is the similarity of the atomic nitrogen-to-phosphorus ratio (N:P)=16 found in waters throughout the deep ocean and in the plankton in the upper ocean. Although A.C. Redfield proposed in 1934 that the intracellular properties of plankton were central to this pattern, no theoretical significance for N:P=16 in cells had been found. Here, we use theoretical modelling and a compilation of literature data for prokaryotic and eukaryotic microbes to show that the balance between two fundamental processes, protein and rRNA synthesis, results in a stable biochemical attractor that homoeostatically produces a given protein:rRNA ratio. Furthermore, when biochemical constants and reasonable kinetic parameters for protein synthesis and ribosome production under nutrient-replete conditions are applied in the model, it predicts a stable protein:rRNA ratio of 3±0.7, which corresponds to N:P=16±3. The model also predicts that N-limitation, by constraining protein synthesis rates, will result in N:P ratios below the Redfield value while P-limitation, by constraining RNA production rates, will produce ratios above the Redfield value. Hence, one of most biogeochemically significant patterns on Earth is inherently rooted in the fundamental structure of life. © 2011 Blackwell Publishing Ltd/CNRS.


The Hadar paleoanthropological site in Ethiopia preserves a record of hominin evolution spanning from approximately 3.45Ma to 0.8Ma. An angular unconformity just above the ca. 2.95Ma BKT-2 complex divides the sediments into the Hadar Formation (ca. 3.8-2.9Ma) and the Busidima Formation (ca. 2.7-0.15Ma). The unconformity is likely a response to a major tectonic reorganization in the Afar Depression, and activation of the As Duma fault near the Ethiopian Escarpment (west of Hadar) created a half-graben in which the Busidima Formation was deposited. The pattern and character of sedimentation in the region changed dramatically above the unconformity, as cut-and-fill channel conglomerates and silt-dominated paleosols that comprise the Busidima Formation stand in sharp contrast to the underlying deposits of the Hadar Formation. Conglomerate deposition has been related to both the perennial, axial paleo-Awash and ephemeral, escarpment-draining tributaries. Overbank silts have yielded fossils attributed to early Homo and Oldowan stone tools. Numerous tuffaceous deposits exist within the Busidima Formation, but they are often spatially limited, fine-grained, and reworked. Recent work on the tephrostratigraphic framework of the Busidima Formation at Hadar has identified at least 12 distinct vitric tephras and established the first geochemical-based correlations between Hadar and the neighboring project areas of Gona and Dikika. Compared to Gona and Dikika, where Busidima Formation sediments are exposed over large areas, the highly discontinuous sediments at Hadar comprise less than 40m in composite section and are exposed over an area of <20km 2, providing only snapshots into the 2.7-0.15Ma window. The stratigraphic record at Hadar confirms the complex depositional history of the Busidima Formation, and also provides important details on regional stratigraphic correlations and the pattern of deposition and erosion in the lower Awash Valley reflective of its tectonic history. © 2011 Elsevier Ltd.


Cai Y.-F.,Arizona State University | Saridakis E.N.,Chongqing University of Posts and Telecommunications
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2011

We investigate thermal inflation in double-screen entropic cosmology. We find that its realization is general, resulting from the system evolution from non-equilibrium to equilibrium. Furthermore, going beyond the background evolution, we study the primordial curvature perturbations arising from the universe interior, as well as from the thermal fluctuations generated on the holographic screens. We show that the power spectrum is nearly scale-invariant with a red tilt, while the tensor-to-scalar ratio is in agreement with observations. Finally, we examine the non-Gaussianities of primordial curvature perturbations, and we find that a sizable value of the non-linearity parameter is possible due to holographic statistics on the outer screen. © 2011 Elsevier B.V.


The link between immigration and crime has garnered considerable attention from researchers. Although the weight of evidence suggests that immigration is not linked to crime, the public consistently views immigrants, especially undocumented immigrants, as criminal and thus a threat to social order. However, little attention has been paid to why they are perceived this way. By drawing on the minority threat perspective, this article investigates the effects of objective and perceptual measures of community context on perceived criminal threat from undocumented immigrants. Analyses of data collected from four Southwest states and the U.S. Census show that the perceived size of the undocumented immigrant population, more so than the actual size of the immigrant population and economic conditions, is positively associated with perceptions of undocumented immigrants as a criminal threat. Additional analyses show that objective measures of community context do not affect native respondents' perceptions of the size of the undocumented immigrant population. The study's findings and their implications for theory, research, and policy are discussed. © 2012 American Society of Criminology.


Gaesser G.A.,Arizona State University
The Physician and sportsmedicine | Year: 2011

Diet and/or exercise are routinely advised as methods for weight loss in overweight/obese individuals, particularly those who are at high risk for cardiovascular disease and type 2 diabetes mellitus. However, physical activity and structured exercise programs rarely result in significant loss of body weight or body fat, and weight-loss diets have extraordinarily high recidivism rates. Despite only modest effects on body weight, exercise and ad libitum nutrient-dense diets for overweight/obese individuals have many health benefits, including skeletal muscle adaptations that improve fat and glucose metabolism, and insulin action; enhance endothelial function; have favorable changes in blood lipids, lipoproteins, and hemostatic factors; and reduce blood pressure, postprandial lipemia and glycemia, and proinflammatory markers. These lifestyle-induced adaptations occur independently of changes in body weight or body fat. Thus, overweight/obese men and women who are at increased risk for cardiovascular disease and type 2 diabetes as a result of sedentary lifestyle, poor diet, and excess body weight should be encouraged to engage in regular physical activity and improve their diet, regardless of whether the healthier lifestyle leads to weight loss.


Kang Y.,Arizona State University
Mathematical Biosciences | Year: 2013

In this article, we study population dynamics of a general two-species discrete-time competition model where each species suffers from both strong Allee effects and scramble intra-specific competitions. We focus on how the combinations of the scramble intra-specific and inter-specific competition affect the extinction and coexistence of these two competing species where each species is subject to strong Allee effects. We derive sufficient conditions on the extinction, essential-like extinction and coexistence for such models. One of the most interesting findings is that scramble competitions can promote coexistence of these two species at their high densities. This is supported by the outcome of single species models with strong Allee effects. In addition, we apply theoretical results to a symmetric competition model with strong Allee effects induced by predator saturations where we give a completed study of its possible equilibria and attractors. Numerical simulations are performed to support our results. © 2012 Elsevier Inc.


Bauer E.,Arizona State University
Journal of Electron Spectroscopy and Related Phenomena | Year: 2012

The evolution of cathode lens-based photo emission electron microscopy (PEEM) from the simple beginnings in the early 1930s to its sophisticated present state is discussed. In addition to conventional ultraviolet light-excited PEEM (UV-PEEM), laser excited PEEM and the various modes of synchrotron X-ray-excited PEEM (XPEEM) particular emphasis is placed on the complementary combination of these methods with low energy electron microscopy (LEEM). © 2012 Elsevier B.V.


O'Keeffe M.,Arizona State University | O'Keeffe M.,University of California at Los Angeles | Yaghi O.M.,University of California at Los Angeles | Yaghi O.M.,Korea Advanced Institute of Science and Technology
Chemical Reviews | Year: 2012

The identification and description of the nets that describe the underlying topology of metal-organic frameworks (MOF) is presented. Alexandrov et al. discussed a crystal of linked paddle wheels reported by Chun. In this material, the four points of extension of the Zn 2(CO 2) 4 paddle wheel are linked to methyl isophthalic acid. A MOF formed by coordination of alkali metal ions by γ-cyclodextrin (CD), a symmetrical cyclic oligosaccharide consisting of a ring of eight C 6 monosaccharide units that is readily available in large quantities, is also studied. A structure discussed by Alexandrov et al. consists of CuN 6 octahedra linked by triazole/tetrazole linkers. The net is identified as a binodal (4,6)-c net with vertices corresponding to the Cu atoms, and the center of the linkers are considered as tetratopic.


Carey E.J.,Mayo Medical School | Ali A.H.,Mayo Medical School | Lindor K.D.,Mayo Medical School | Lindor K.D.,Arizona State University
The Lancet | Year: 2015

Summary Primary biliary cirrhosis is a chronic cholestatic liver disease characterised by destruction of small intrahepatic bile ducts, leading to fibrosis and potential cirrhosis through resulting complications. The serological hallmark of primary biliary cirrhosis is the antimitochondrial antibody, a highly disease-specific antibody identified in about 95% of patients with primary biliary cirrhosis. These patients usually have fatigue and pruritus, both of which occur independently of disease severity. The typical course of primary biliary cirrhosis has changed substantially with the introduöction of ursodeoxycholic acid (UDCA). Several randomised placebo-controlled studies have shown that UDCA improves transplant-free survival in primary biliary cirrhosis. However, about 40% of patients do not have a biochemical response to UDCA and would benefit from new therapies. Liver transplantation is a life-saving surgery with excellent outcomes for those with decompensated cirrhosis. Meanwhile, research on nuclear receptor hormones has led to the development of exciting new potential treatments. This Seminar will review the current understanding of the epidemiology, pathogenesis, and natural history of primary biliary cirrhosis, discuss management of the disease and its sequelae, and introduce research on new therapeutic options. © 2015 Elsevier Ltd.


Gratz K.L.,University of Mississippi Medical Center | Tull M.T.,University of Mississippi Medical Center | Levy R.,Arizona State University
Psychological Medicine | Year: 2014

Background Despite the clinical importance of deliberate self-harm (DSH; also referred to as non-suicidal self-injury) within borderline personality disorder (BPD), empirically supported treatments for this behavior among individuals with BPD are difficult to implement in many clinical settings. To address this limitation, a 14-week, adjunctive emotion regulation group therapy (ERGT) for DSH among women with BPD was developed. The current study examined the efficacy of this ERGT in a randomized controlled trial (RCT) and the durability of treatment gains over a 9-month uncontrolled follow-up period. Method Female out-patients with BPD and recent recurrent DSH were randomly assigned to receive this ERGT in addition to their ongoing out-patient therapy immediately (n = 31) or after 14 weeks (n = 30). Measures of DSH and other self-destructive behaviors, psychiatric symptoms, adaptive functioning and the proposed mechanisms of change (emotion dysregulation/avoidance) were administered pre- and post-treatment or -waitlist (to assess treatment efficacy), and 3 and 9 months post-treatment (to assess durability of treatment gains). Results Intent-to-treat (ITT) analyses (n = 61) revealed significant effects of this ERGT on DSH and other self-destructive behaviors, emotion dysregulation, BPD symptoms, depression and stress symptoms, and quality of life. Analyses of all participants who began ERGT (across treatment and waitlist conditions; n = 51) revealed significant improvements from pre- to post-treatment on all outcomes, additional significant improvements from post-treatment to 9-month follow-up for DSH, emotion dysregulation/avoidance, BPD symptoms and quality of life, and no significant changes from post-treatment to 9-month follow-up on the other measures. Conclusions The results support the efficacy of this ERGT and the durability of treatment gains. © Cambridge University Press 2013.


Hihath J.,University of California at Davis | Tao N.,Arizona State University
Progress in Surface Science | Year: 2012

Electron-phonon interactions are extremely important for understanding charge transport, inelastic processes, heating, and heat dissipation in nanoscale molecular and atomic devices. In molecular electronics Inelastic Electron Tunneling Spectroscopy (IETS) has recently emerged as one of the premier methods for characterizing molecular-scale junctions and devices. This method provides a distinct chemical fingerprint for identifying molecules within a junction, and has allowed for clear demonstrations of single molecule devices, the effects of electric field on molecular orbitals, the importance of molecular configuration on conductance, as well as information about the charge transport mechanism. In this review we will discuss the use of Point Contact (PC) and IET spectroscopies on molecular and atomic systems, discuss the basic principles involved in inelastic transport for these spectroscopic methods to function, and focus on the experimental techniques involved and the important conclusions drawn from the experiments performed to date. © 2012 Elsevier Ltd. All rights reserved.


Elser J.J.,Arizona State University
Current Opinion in Biotechnology | Year: 2012

Phosphorus is a chemical element that is essential to life because of its role in numerous key molecules, including DNA and RNA; indeed, organisms require large amounts of P to grow rapidly. However, the supply of P from the environment is often limiting to production, including to crops. Thus, large amounts of P are mined annually to produce fertilizer that is applied in support of the 'Green Revolution.' However, much of this fertilizer eventually ends up in rivers, lakes and oceans where it causes costly eutrophication. Furthermore, given increasing human population, expanding meat consumption, and proliferating bioenergy pressures, concerns have recently been raised about the long-term geological, economic, and geopolitical viability of mined P for fertilizer production. Together, these issues highlight the non-sustainable nature of current human P use. To achieve P sustainability, farms need to become more efficient in how they use P while society as a whole must develop technologies and practices to recycle P from the food chain. Such large-scale changes will probably require a radical restructuring of the entire food system, highlighting the need for prompt but sustained action. © 2012 Elsevier Ltd.


We developed regulated delayed attenuation strategies for Salmonella vaccine vectors. In this study, we evaluated the combination of these strategies in recombinant attenuated Salmonella enterica serovar Typhi and Salmonella enterica serovar Typhimurium vaccine vectors with similar genetic backgrounds in vitro and in vivo. Our goal is to develop a vaccine to prevent Streptococcus pneumoniae infection in newborns; thus, all strains delivered a pneumococcal antigen PspA and the impact of maternal antibodies was evaluated. The results showed that all strains with the regulated delayed attenuated phenotype (RDAP) displayed an invasive ability stronger than that of the S. Typhi vaccine strain, Ty21a, but weaker than that of their corresponding wild-type parental strains. The survival curves of different RDAP vaccine vectors in vitro and in vivo exhibited diverse regulated delayed attenuation kinetics, which was different from S. Typhi Ty21a and the wild-type parental strains. Under the influence of maternal antibody, the persistence of the S. Typhimurium RDAP strain displayed a regulated delayed attenuation trend in nasal lymphoid tissue (NALT), lung, and Peyer's patches, while the persistence of S. Typhi RDAP strains followed the curve only in NALT. The bacterial loads of S. Typhi RDAP strains were lower in NALT, lung, and Peyer's patches in mice born to immune mothers than in those born to naive mothers. In accordance with these results, RDAP vaccine strains induced high titers of IgG antibodies against PspA and against Salmonella lipopolysaccharides. Immunization of mothers with S. Typhi RDAP strains enhanced the level of vaginal mucosal IgA, gamma interferon (IFN-γ), and interleukin 4 (IL-4) and resulted in a higher level of protection against S. pneumoniae challenge.


Roth S.H.,Arizona State University
Clinical Interventions in Aging | Year: 2011

Chronic oral or systemic nonselective nonsteroidal anti-inflammatory drug (NSAID) therapy, ubiquitously used by physicians to treat osteoarthritis-associated pain, is associated with a wide range of symptomatic adverse events, the most frequent and serious of which is gastropathy. Although cardiovascular and renal problems are a very real concern, they are significantly less frequent. These complications can be life-threatening in at-risk populations such as older adults, who are common users of long-term oral systemic NSAID therapy. Topical NSAID formulations deliver effective doses of analgesics directly to the affected joints, thereby limiting systemic exposure and potentially the risk of systemic adverse events, such as gastropathy and serious cardiovascular events. There are currently two topical NSAIDs approved by the US Food and Drug Administration for osteoarthritis-associated pain, as well as for the signs and symptoms of osteoarthritis. This review discusses the relative safety, and the gastrointestinal, cardiovascular, and renal risks of chronic oral or systemic NSAID therapy and topical NSAID formulations in patients with osteoarthritis. © 2011 Roth, publisher and licensee Dove Medical Press Ltd.


Wang H.,Arizona State University
Journal of Nonlinear Science | Year: 2011

Much has been studied on the spreading speed and traveling wave solutions for cooperative reaction-diffusion systems. In this paper, we shall establish the spreading speed for a large class of non-cooperative reaction-diffusion systems and characterize the spreading speed as the slowest speed of a family of non-constant traveling wave solutions. Our results are applied to a partially cooperative system describing interactions between ungulates and grass. © 2011 Springer Science+Business Media, LLC.


Hedrick P.W.,Arizona State University
Heredity | Year: 2011

The high mortality and widespread impact of malaria have resulted in this disease being the strongest evolutionary selective force in recent human history, and genes that confer resistance to malaria provide some of the best-known case studies of strong positive selection in modern humans. I begin by reviewing JBS Haldane's initial contribution to the potential of malaria genetic resistance in humans. Further, I discuss the population genetics aspects of many of the variants, including globin, G6PD deficiency, Duffy, ovalocytosis, ABO and human leukocyte antigen variants. Many of the variants conferring resistance to malaria are loss-of-function mutants and appear to be recent polymorphisms from the last 5000-10 000 years or less. I discuss estimation of selection coefficients from case-control data and make predictions about the change for S, C and G6PD-deficiency variants. In addition, I consider the predicted joint changes when the two Β-globin alleles S and C are both variable in the same population and when there is a variation for α-thalassemia and S, two unlinked, but epistatic variants. As more becomes known about genes conferring genetic resistance to malaria in humans, population genetics approaches can contribute both to investigating past selection and predicting the consequences in future generations for these variants. © 2011 Macmillan Publishers Limited All rights reserved.


Lindell M.K.,Texas A&M University | Perry R.W.,Arizona State University
Risk Analysis | Year: 2012

The Protective Action Decision Model (PADM) is a multistage model that is based on findings from research on people's responses to environmental hazards and disasters. The PADM integrates the processing of information derived from social and environmental cues with messages that social sources transmit through communication channels to those at risk. The PADM identifies three critical predecision processes (reception, attention, and comprehension of warnings or exposure, attention, and interpretation of environmental/social cues)-that precede all further processing. The revised model identifies three core perceptions-threat perceptions, protective action perceptions, and stakeholder perceptions-that form the basis for decisions about how to respond to an imminent or long-term threat. The outcome of the protective action decision-making process, together with situational facilitators and impediments, produces a behavioral response. In addition to describing the revised model and the research on which it is based, this article describes three applications (development of risk communication programs, evacuation modeling, and adoption of long-term hazard adjustments) and identifies some of the research needed to address unresolved issues. © 2011 Society for Risk Analysis.


Xie M.,Arizona State University
Journal of Quantitative Criminology | Year: 2010

Past research examining the association between residential segregation and homicide victimization has often considered only one dimension of segregation, and the literature that does use a multidimensional approach has not presented a uniform set of findings. The majority of the studies have focused on the experiences of Blacks, while overlooking the possibility that the differences between the structure of Black and Hispanic communities may alter the conclusions for Hispanics. In this study, we argue that in order to understand the mechanisms underlying the effects of segregation on homicide, we need to understand the multidimensional structure of Black and Hispanic segregation, and examine whether the relationship between segregation and homicide differs for Blacks and Hispanics. Using 2000 census data and homicide data from the National Vital Statistics System (1999-2001) for U. S. metropolitan areas, we identify two empirically distinct superdimensions of segregation (group separateness and centralized concentration), both of which have a substantial positive and statistically significant impact on homicide victimization for both Blacks and Hispanics. © 2009 Springer Science+Business Media, LLC.


Millsap R.E.,Arizona State University
Child Development Perspectives | Year: 2010

Item response theory (IRT) consists of a set of mathematical models for the probabilities of various responses to test items as a function of item and person characteristics. In longitudinal data, changes in measured variables can only be interpreted if important psychometric features of the measured variables are assumed invariant across time. Measurement invariance is invariance in the relation of a measure to the latent variable underlying it. Measurement invariance in longitudinal studies concerns invariance over time, and IRT provides a useful approach to investigating longitudinal measurement invariance. Commonly used IRT models are described, along with the representation of measurement invariance in IRT. The use of IRT for investigating invariance is then described, along with practical considerations in using IRT for this purpose. Conceptual issues, rather than technical details, are emphasized throughout. © 2010, Copyright the Author(s). Journal Compilation © 2010, Society for Research in Child Development.


Herrendorf B.,Arizona State University | Valentinyi A.,Institute of Economics HAS and CEPR
Journal of the European Economic Association | Year: 2012

Which sectors are most responsible for the low total factor productivities of developing countries? To answer this question we develop a new framework for sectoral development accounting. Applying this framework to the Penn World Table, we find that in equipment, construction, and food the sectoral TFP differences between developing countries and the United States are much larger than in the aggregate. However, in manufactured consumption the sectoral TFP differences are about equal to the aggregate TFP differences, and in services they are much smaller. We show that our level of disaggregation allows us to reconcile the results of existing studies of sectoral productivity differences, which have focused on noncomparable two-sector decompositions of the aggregate data. We also show that our results help shed light on existing theories of aggregate TFP differences. © 2011 by the European Economic Association.


Ning C.Z.,Arizona State University
Physica Status Solidi (B) Basic Research | Year: 2010

Semiconductor nanolasers represent the current frontier of research in the confluencing area of nanotechnology (or nanophotonics) and semiconductor lasers. In this paper, we review some of the most exciting progress made recently in the area. We will focus on nanoscale lasers made of semiconductor nanowires grown in a bottom-up fashion or nanopillars that are produced through a top-down wafer etching. Special features of these nanolasers will be reviewed. In particular, recent results on metal-semiconductor plasmonic lasers will be presented which represents the smallest lasers by taking advantages of surface plasmonic effects. Due to the small size and strong confinement in these nanolasers, certain familiar concepts in semiconductor-laser physics need to be re-examined to determine their validity or implication at nanoscale. These include the concept of modal gain and confinement factor (CF). The seemly abnormal behavior of CF in dielectric and plasmonic nanolasers will be explained from a unified point of view. Throughout this tutorial, we attempt to address the question of how small a laser can be made or whether there exists an ultimate size limit for a laser. Laser intensity profile along a nanowire laser. The nanowire laser is confined to the left by the substrate and surrounded by air from all other sides. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Chester M.,Arizona State University | Horvath A.,University of California at Berkeley
Environmental Research Letters | Year: 2012

Sustainable mobility policy for long-distance transportation services should consider emerging automobiles and aircraft as well as infrastructure and supply chain life-cycle effects in the assessment of new high-speed rail systems. Using the California corridor, future automobiles, high-speed rail and aircraft long-distance travel are evaluated, considering emerging fuel-efficient vehicles, new train designs and the possibility that the region will meet renewable electricity goals. An attributional per passenger-kilometer-traveled life-cycle inventory is first developed including vehicle, infrastructure and energy production components. A consequential life-cycle impact assessment is then established to evaluate existing infrastructure expansion against the construction of a new high-speed rail system. The results show that when using the life-cycle assessment framework, greenhouse gas footprints increase significantly and human health and environmental damage potentials may be dominated by indirect and supply chain components. The environmental payback is most sensitive to the number of automobile trips shifted to high-speed rail, and for greenhouse gases is likely to occur in 20-30years. A high-speed rail system that is deployed with state-of-the-art trains, electricity that has met renewable goals, and in a configuration that endorses high ridership will provide significant environmental benefits over existing modes. Opportunities exist for reducing the long-distance transportation footprint by incentivizing large automobile trip shifts, meeting clean electricity goals and reducing material production effects. © 2012 IOP Publishing Ltd.


Nielsen U.N.,University of Western Sydney | Ball B.A.,Arizona State University
Global Change Biology | Year: 2015

Altered precipitation patterns resulting from climate change will have particularly significant consequences in water-limited ecosystems, such as arid to semi-arid ecosystems, where discontinuous inputs of water control biological processes. Given that these ecosystems cover more than a third of Earth's terrestrial surface, it is important to understand how they respond to such alterations. Altered water availability may impact both aboveground and belowground communities and the interactions between these, with potential impacts on ecosystem functioning; however, most studies to date have focused exclusively on vegetation responses to altered precipitation regimes. To synthesize our understanding of potential climate change impacts on dryland ecosystems, we present here a review of current literature that reports the effects of precipitation events and altered precipitation regimes on belowground biota and biogeochemical cycling. Increased precipitation generally increases microbial biomass and fungal:bacterial ratio. Few studies report responses to reduced precipitation but the effects likely counter those of increased precipitation. Altered precipitation regimes have also been found to alter microbial community composition but broader generalizations are difficult to make. Changes in event size and frequency influences invertebrate activity and density with cascading impacts on the soil food web, which will likely impact carbon and nutrient pools. The long-term implications for biogeochemical cycling are inconclusive but several studies suggest that increased aridity may cause decoupling of carbon and nutrient cycling. We propose a new conceptual framework that incorporates hierarchical biotic responses to individual precipitation events more explicitly, including moderation of microbial activity and biomass by invertebrate grazing, and use this framework to make some predictions on impacts of altered precipitation regimes in terms of event size and frequency as well as mean annual precipitation. While our understanding of dryland ecosystems is improving, there is still a great need for longer term in situ manipulations of precipitation regime to test our model. © 2014 John Wiley & Sons Ltd.


Zhuang X.,Hunan University | Ning C.Z.,Arizona State University | Pan A.,Hunan University
Advanced Materials | Year: 2012

Semiconductor alloy nanowires with spatially graded compositions (and bandgaps) provide a new material platform for many new multifunctional optoelectronic devices, such as broadly tunable lasers, multispectral photodetectors, broad-band light emitting diodes (LEDs) and high-efficiency solar cells. In this review, we will summarize the recent progress on composition graded semiconductor alloy nanowires with bandgaps graded in a wide range. Depending on different growth methods and material systems, two typical nanowire composition grading approaches will be presented in detail, including composition graded alloy nanowires along a single substrate and those along single nanowires. Furthermore, selected examples of applications of these composition graded semiconductor nanowires will be presented and discussed, including tunable nanolasers, multi-terminal on-nanowire photodetectors, full-spectrum solar cells, and white-light LEDs. Finally, we will make some concluding remarks with future perspectives including opportunities and challenges in this research area. Semiconductor alloy nanowires with spatially graded compositions (and bandgaps) provide a new material platform for many new multifunctional optoelectronic devices, such as broadly tunable lasers, multispectral photodetectors, broad-band light emitting diodes (LEDs) and high-efficiency solar cells. Here, recent studies on composition or bandgap-graded semiconductor alloy nanowires based on a single substrate or along single nanowires are reviewed. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


This study explores the association between parental perception of the nutritional quality of school meals and whether students eat lunch served at school. We use data from five low-income cities in New Jersey that have high minority populations. Students whose parents perceive the quality of school meals to be healthy have greater odds of eating meals served at school. Recent changes in guidelines for the United States Department of Agriculture's National School Lunch Program met with resistance from several fronts. Advocates for and implementers of improved school meals may benefit from partnering with parents to increase the acceptance and utilization of improved school offerings. © 2013 Elsevier Ltd.


Wolfe S.E.,Arizona State University | Piquero A.R.,Florida State University
Criminal Justice and Behavior | Year: 2011

Although police misconduct has interested policing scholars for many years, extant research has been largely atheoretical and has ignored the role of organizational justice in understanding the behavior. This study uses survey data from a random sample of 483 police officers employed in the Philadelphia Police Department to explore the role of organizational justice in police misconduct. Results indicate that officers who view their agency as fair and just in managerial practices are less likely to adhere to the code of silence or believe that police corruption in pursuit of a noble cause is justified. Furthermore, perceptions of organizational justice are associated with lower levels of engagement in several forms of police misconduct. The results suggest that organizational justice is a promising framework to understand police misconduct and may help guide police administrators in the implementation of effective management strategies to reduce the incidence of the behavior. © 2011 International Association for Correctional and Forensic Psychology.


Simons R.L.,University of Georgia | Burt C.H.,Arizona State University
Criminology | Year: 2011

In this article, we develop and test a new approach to explain the link between social factors and individual offending. We argue that seemingly disparate family, peer, and community conditions lead to crime because the lessons communicated by these events are similar and promote social schemas involving a hostile view of people and relationships, a preference for immediate rewards, and a cynical view of conventional norms. Furthermore, we posit that these three schemas are interconnected and combine to form a criminogenic knowledge structure that results in situational interpretations legitimating criminal behavior. Structural equation modeling with a sample of roughly 700 African American teens provided strong support for the model. The findings indicated that persistent exposure to adverse conditions such as community crime, discrimination, harsh parenting, deviant peers, and low neighborhood collective efficacy increased commitment to the three social schemas. The three schemas were highly intercorrelated and combined to form a latent construct that strongly predicted increases in crime. Furthermore, in large measure, the effect of the various adverse conditions on increases in crime was indirect through their impact on this latent construct. We discuss the extent to which the social-schematic model presented in this article might be used to integrate concepts and findings from several major theories of criminal behavior. © 2011 American Society of Criminology.


Newbern J.M.,Arizona State University
Current Topics in Developmental Biology | Year: 2015

A transient and unique population of multipotent stem cells, known as neural crest cells (NCCs), generate a bewildering array of cell types during vertebrate development. An attractive model among developmental biologists, the study of NCC biology has provided a wealth of knowledge regarding the cellular and molecular mechanisms important for embryogenesis. Studies in numerous species have defined how distinct phases of NCC specification, proliferation, migration, and survival contribute to the formation of multiple functionally distinct organ systems. NCC contributions to the peripheral nervous system (PNS) are well known. Critical developmental processes have been defined that provide outstanding models for understanding how extracellular stimuli, cell-cell interactions, and transcriptional networks cooperate to direct cellular diversification and PNS morphogenesis. Dissecting the complex extracellular and intracellular mechanisms that mediate the formation of the PNS from NCCs may have important therapeutic implications for neurocristopathies, neuropathies, and certain forms of cancer. © 2015 Elsevier Inc.


Ravikumar D.,Clarkson University | Neithalath N.,Arizona State University
Cement and Concrete Composites | Year: 2012

The influence of different levels of alkalinity, expressed using the Na 2O-to-source material ratio (n) and activator SiO 2-to-Na 2O ratio (M s), on the compressive strength development of, and reaction product formation in sodium silicate and NaOH powder activated slag binder systems is discussed. Higher n value mixtures are found to exhibit higher early and later age compressive strengths. An increase in M s results in reduced early age and slightly increased later age strengths. Compositional coefficients, which are functions of n and M s are proposed, that relate to the early and later age strengths of the activated slag binders as well as to the shift in the FTIR spectra. The reaction product formation in these systems as a function of the total alkalinity is explained using the shifts of the dominant peak in the FTIR spectra. Fundamental changes in reaction products of powder activated binders as a function of alkalinity is observed. The deductions from the peak shifts are substantiated using the FTIR spectra of the pastes before and after salicylic acid-methanol (SAM) attack. © 2012 Elsevier Ltd. All rights reserved.


Hampton S.E.,National Center for Ecological Analysis And Synthesis | Parker J.N.,Arizona State University
BioScience | Year: 2011

Scientific synthesis has transformed ecological research and presents opportunities for advancements across the sciences; to date, however, little is known about the antecedents of success in synthesis. Building on findings from 10 years of detailed research on social interactions in synthesis groups at the National Center for Ecological Analysis and Synthesis, we demonstrated with large-scale quantitative analyses that face-to-face interaction has been vital to success in synthesis groups, boosting the production of peer-reviewed publications. But it has been about more than just meeting; the importance of resident scientists at synthesis centers was also evident, in that including synthesis-center residents in geographically distributed working groups further increased productivity. Moreover, multi-institutional collaboration, normally detrimental to productivity, was positively associated with productivity in this stimulating environment. Finally, participation in synthesis groups significantly increased scientists' collaborative propensity and visibility, positively affecting scientific careers and potentially increasing the capacity of the scientific community to leverage synthesis for enhanced scientific understanding. © 2011 by American Institute of Biological Sciences. All rights reserved.


Chowell G.,Arizona State University | Nishiura H.,University of Tokyo
BMC medicine | Year: 2014

The complex and unprecedented Ebola epidemic ongoing in West Africa has highlighted the need to review the epidemiological characteristics of Ebola Virus Disease (EVD) as well as our current understanding of the transmission dynamics and the effect of control interventions against Ebola transmission. Here we review key epidemiological data from past Ebola outbreaks and carry out a comparative review of mathematical models of the spread and control of Ebola in the context of past outbreaks and the ongoing epidemic in West Africa. We show that mathematical modeling offers useful insights into the risk of a major epidemic of EVD and the assessment of the impact of basic public health measures on disease spread. We also discuss the critical need to collect detailed epidemiological data in real-time during the course of an ongoing epidemic, carry out further studies to estimate the effectiveness of interventions during past outbreaks and the ongoing epidemic, and develop large-scale modeling studies to study the spread and control of viral hemorrhagic fevers in the context of the highly heterogeneous economic reality of African countries.


Desch S.J.,Arizona State University | Turner N.J.,Jet Propulsion Laboratory
Astrophysical Journal | Year: 2015

We calculate the abundances of electrons and ions in the hot (500 K), dusty parts of protoplanetary disks, treating for the first time the effects of thermionic and ion emission from the dust grains. High-temperature ionization modeling has involved simply assuming that alkali elements such as potassium occur as gas-phase atoms and are collisionally ionized following the Saha equation. We show that the Saha equation often does not hold, because free charges are produced by thermionic and ion emission and destroyed when they stick to grain surfaces. This means the ionization state depends not on the first ionization potential of the alkali atoms, but rather on the grains' work functions. The charged species' abundances typically rise abruptly above about 800 K, with little qualitative dependence on the work function, gas density, or dust-to-gas mass ratio. Applying our results, we find that protoplanetary disks' dead zone, where high diffusivities stifle magnetorotational turbulence, has its inner edge located where the temperature exceeds a threshold value ≈1000 K. The threshold is set by ambipolar diffusion except at the highest densities, where it is set by Ohmic resistivity. We find that the disk gas can be diffusively loaded onto the stellar magnetosphere at temperatures below a similar threshold. We investigate whether the "short-circuit" instability of current sheets can operate in disks and find that it cannot, or works only in a narrow range of conditions; it appears not to be the chondrule formation mechanism. We also suggest that thermionic emission is important for determining the rate of Ohmic heating in hot Jupiters. © 2015. The American Astronomical Society. All rights reserved..


An emerging body of research targets women's relationship to their genitals, particularly as pubic hair removal and the promotion of female genital surgeries increase in popularity and visibility. This study asked women to discuss their subjective feelings about three related but distinct genital attitudes: pubic hair grooming, sex during menstruation, and genital/vaginal self-image. Specifically, this study applied thematic analysis to qualitative interviews with a community sample of 20 women (mean age. = 34, SD= 13.35) from diverse ages, races, and sexual identity backgrounds to illuminate seven themes in women's narratives about their vaginas: (1) "dirty" or "gross", (2) needing maintenance; (3) unknown or frustrating; (4) unnatural; (5) comparative; (6) ambivalent; (7) affirmative. Overwhelmingly, women used strong emotional language when discussing their genitals, often evoking descriptions of anxiety, excess, and need for control. Fusions between sexuality and body image, and connections between "genital panics" and internalized racism, sexism, and homophobia, also appeared. © 2014 .


Langley P.,Arizona State University
Machine Learning | Year: 2011

The latest issue of Machine Learning dealt with the changes being introduced in the area. Early research on machine learning adopted an informal approach to evaluation. Kibler and Langley were two researchers who established a framework for such an experimental science of machine learning, including examples from the emerging literature in this area. The experimental effort in the area was aided by another development when David Aha, a PhD student at UCI started collecting data sets for use in empirical studies of machine learning. The early research effort machine learning was also characterized by an emphasis on symbolic representations of learned knowledge, such as production rules, decision trees, and logical formulae. One of the significant changes introduced in the area involved an increased emphasis on classification and regression tasks in comparison with more complex tasks, such as reasoning, problem solving, and language understanding that had played important roles earlier.


Ketokivi M.,IE University | Choi T.,Arizona State University
Journal of Operations Management | Year: 2014

Since the seminal article by Eisenhardt (1989), scholarly interest in case research has mushroomed in operations management and organization sciences. Volumes of methodological texts are matched with a massive amount of empirical research that seeks to apply and further develop case research as a scientific method. What is missing from this literature is a treatment of the methodological diversity of case research. In this paper, we seek to unveil this heterogeneity by describing three distinct methodological accounts of case study: theory generation, theory testing, and theory elaboration. Each approach has its own idiosyncrasies, in particular when it comes to the interplay between theory and empirics. A typical case research incorporates both existing theories and empirical data to varying degrees. In light of this heterogeneity, we re-interpret key aspects of extant contributions and discuss guidelines for future case research. We propose that ultimately, case research rigor is determined by attention to idiosyncrasy and transparency of reasoning. We conclude by arguing that we have witnessed in the past 25 years in organization research what amounts to the Renaissance of case research. © 2014 Elsevier B.V.


Watkins M.W.,Baylor University | Smith L.G.,Arizona State University
Psychological Assessment | Year: 2013

Long-term stability of the Wechsler Intelligence Scale for Children-Fourth Edition (WISC-IV; Wechsler, 2003) was investigated with a sample of 344 students from 2 school districts twice evaluated for special education eligibility at an average interval of 2.84 years. Test-retest reliability coefficients for the Verbal Comprehension Index (VCI), Perceptual Reasoning Index (PRI), Working Memory Index (WMI), Processing Speed Index (PSI), and the Full Scale IQ (FSIQ) were .72, .76, .66, .65, and .82, respectively. As predicted, the test-retest reliability coefficients for the subtests (Mdn .56) were generally lower than the index scores (Mdn .69) and the FSIQ (.82). On average, subtest scores did not differ by more than 1 point, and index scores did not differ by more than 2 points across the test-retest interval. However, 25% of the students earned FSIQ scores that differed by 10 or more points, and 29%, 39%, 37%, and 44% of the students earned VCI, PRI, WMI, and PSI scores, respectively, that varied by 10 or more points. Given this variability, it cannot be assumed that WISC-IV scores will be consistent across long test-retest intervals for individual students. © 2013 American Psychological Association.


Chen B.,Chinese Environmental Scholars and Professionals Network | Westerhoff P.,Arizona State University
Water Research | Year: 2010

Formation of regulated and non-regulated disinfection by-products (DBPs) is an issue at both potable water and wastewater treatment plants (W/WWTPs). Water samples from W/WWTPs across the USA were collected and DBP formation potentials (DBPFPs) in the presence of free chlorine and chloramine were obtained for trihalomethane (THM), haloacetic acid (HAA), haloacetonitrile (HAN), and N-nitrosodimethylamine (NDMA). With nearly 200 samples covering a range of dissolved organic carbon (0.6-23mg/L), ultraviolet absorbance (0.01-0.48cm-1 at 254nm wavelength), and bromide (0-1.0mg/L) levels, power function models were developed to predict the carbonaceous DBP (C-DBP) and nitrogenous DBP (N-DBP) precursors spanning 3 orders of magnitudes. The predicted THM and HAA formation potentials fitted well with the measured data (analytical variance of less than 22%). Inclusion of dissolved organic nitrogen (DON) into the HANFP model improved the predictions. NDMAFP was the most difficult one to predict based upon the selected water quality parameters, perhaps suggesting that bulk measurements such as DOC or UVA254 were not appropriate for tracking NDMAFP. These are the first such DBPFP models for wastewater systems, and among the few models that consider both C-DBPs and N-DBPs formation potentials from the same water sources. © 2010 Elsevier Ltd.


Robichau R.W.,Arizona State University
Policy Studies Journal | Year: 2011

The popularity of governance can be seen across academic genres. In some ways, the tremendous amount of theorizing on the subject has created contentious areas of debate. However, the approach that I argue will move the discussion forward is a focus on areas of agreement, where studying governance as a form of statecraft is considered. In order to advance the governance conversation, this essay speculates on the intersections of future governance research areas and maintains that making governance studies meaningful involves more empirical testing and inductive explorations by scholars. © 2011 Policy Studies Organization.


Kim J.-G.,Seoul National University | Kuby M.,Arizona State University
Computers and Operations Research | Year: 2013

In the early stages of development, alternative-fuel vehicles will tend to have shorter driving ranges than conventional vehicles, and the availability of stations will be limited. Given these conditions, it is important to consider the willingness of drivers to deviate to some extent from their shortest paths in order to refuel their vehicles and complete their trips. Previously, we proposed the deviation-flow refueling location model (DFRLM) for locating a given number of refueling facilities to maximize the total alternative-fuel vehicle flows that can be refueled by drivers traveling on or deviating from their shortest paths. On a real-world problem, however, the large number of possible deviations from each path and of combinations of facilities that can cover each path would make it extremely difficult to generate and solve the mixed-integer formulation. This paper develops heuristic algorithms for the DFRLM that overcome this difficulty through network transformation. Specifically, a greedy heuristic constructs and edits an artificial feasible network in which each node represents a station, origin, or destination, and each arc represents a feasible path between two nodes given the assumed driving range of vehicles. At each step of the greedy and greedy-substitution algorithms, the feasible network is edited and a shortest path algorithm is run, which determines whether each origin-destination round trip can be completed. This method allows any possible detour to be taken (up to some user-defined maximum) while also ensuring that drivers take the smallest possible detour. Computational experiments on a simple network and a real-world network for Florida show the heuristics to be efficient in solving the problems. Comparisons between the results of the DFRLM and the FRLM indicate that taking driver deviations into account in the model can have a significant effect on the locations chosen and demand covered. © 2012 Elsevier Ltd.


Hayford S.R.,Arizona State University | Guzzo K.B.,Bowling Green State University
Perspectives on Sexual and Reproductive Health | Year: 2013

Context: Racial and ethnic differences in unintended fertility are well documented, but mechanisms underlying these differences are poorly understood. To identify the factors that may contribute to such disparities, differences in distal characteristics theoretically linked to unintended fertility-such as the motivation to avoid a pregnancy-need to be identified. Methods: Data on sexual and reproductive attitudes and behavior among a sample of 1,573 unmarried men and women aged 18-29 came from the 2009 National Survey of Reproductive and Contraceptive Knowledge. Ordinal logistic regression analysis was conducted to examine two measures of motivation: one cognitive (perceived importance of avoiding pregnancy) and one affective (predicted feelings about experiencing an unplanned pregnancy). Results: Seventy-seven percent of young adults reported that avoiding pregnancy is very important, and 34% would be very upset if they were to experience an unplanned pregnancy. In multivariate analyses, the cognitive measure of motivation was not associated with race and ethnicity. The affective measure, however, was: Foreign-born Hispanics would be less upset than whites, and blacks would be more upset than whites, if they were to experience an unplanned pregnancy (coefficients, -1.7 and 0.5, respectively). Conclusions: Differences in motivation to avoid pregnancy-particularly in predicted emotional responses to an unplanned pregnancy-should be further investigated as a potential factor in Hispanics' relatively high rates of unintended births. Future research should also examine connections between motivation to avoid pregnancy and reproductive behavior. © 2013 by the Guttmacher Institute.


Bhakoo V.,University of Melbourne | Choi T.,Arizona State University
Journal of Operations Management | Year: 2013

The healthcare industry has been known to operate in a strong institutional environment (i.e. government regulations), and the implementation of inter-organizational systems (IOS) has followed an institutional process. Extending this perspective across different tiers in the healthcare supply chain, we investigate how organizations in different tiers in the supply chain (i.e. hospitals, distributors and manufacturers) respond to institutional pressures when implementing IOS. How institutional dynamics unfold across multiple tiers of a supply chain is an uncharted area of research, and we take the theory-building case study approach using data collected from ten organizations. Because organizations are embedded in their respective tiers, our within-tier analyses are equivalent to cross-organization analyses. In this regard, the cross-case analyses occur at two different levels: at each tier level (i.e. across multiple hospitals, multiple distributors and multiple manufacturers) and across the supply chain (i.e. across all three tiers). The study shows how different institutional pressures such as coercive, mimetic, and normative manifest across the tiers. It also demonstrates how a differential mix of endogenous and institutional pressures lead to mixed organizational responses across the tiers. The propositions developed from the study enrich institutional theory arguments within the information systems and supply chain management disciplines. They highlight how the IOS implementation dynamics within and across different tiers in a supply chain result in heterogeneous rather than isomorphic consequences, thereby exposing the "iron cage" of institutionalization.


Talen E.,Arizona State University
Environment and Planning B: Planning and Design | Year: 2011

This paper makes a contribution to the suburban retrofit/sprawl repair literature by suggesting a method that planners can use to evaluate the potential of some places to be catalysts for an improvedömore sustainableöurban form. The strategy is aimed at evaluating and then promoting sustainable urban form in unsustainable places. The method puts sprawl retrofit projects into a larger planning framework, suggesting ways to evaluate the strengths and weaknesses of places in relative terms, taking into account how different kinds of nodesöfrom light rail stops to parking lotsö varying with respect