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Amherst, MA, United States

The University of Massachusetts Amherst is a public research and land-grant university in Amherst, Massachusetts, United States, and the flagship of the University of Massachusetts system. With 1,174 faculty members and more than 27,000 students, UMass Amherst is the largest public university in New England and is ranked among top 30 public universities in the nation.The university offers bachelor's degrees, master's degrees, and doctoral degrees in 90 undergraduate and 72 graduate areas of study, through eight schools and colleges. The main campus is situated north of downtown Amherst. In a 2009 article for MSN.com, Amherst was ranked first in Best College Towns in the United States. In 2012, U.S. News and World Report ranked Amherst amongst the Top 10 Great College Towns in America.The University of Massachusetts Amherst is categorized as a Research University with Very High research activity by the Carnegie Foundation for the Advancement of Teaching. In 2011, UMass Amherst had research expenditures of $181.3 million. It is also a member of the Five College Consortium.UMass Amherst sports teams are called the Minutemen and Minutewomen, the colors being maroon and white; the school mascot is Sam the Minuteman. All teams participate in NCAA Division I. The university is a member of the Atlantic 10 Conference, while playing ice hockey in Hockey East. In football, UMass upgraded to the FBS level and transition to the Mid-American Conference . Wikipedia.


Grant
Agency: NSF | Branch: Continuing grant | Program: | Phase: Cyber-Human Systems (CHS) | Award Amount: 197.47K | Year: 2016

Digital representations of three-dimensional shapes are becoming an integral part of many scientific and engineering fields. And 3D printers are becoming increasingly popular for transforming these digital representations into real objects for industrial or home use as tools, mechanical components, or household items. Virtual environments for simulation, education, and entertainment require large numbers of diverse 3D models to maintain realism and operability. In computer vision, several recent object recognition algorithms are trained on large synthetic datasets originating from 3D shape repositories. All these fields and several others increasingly depend on the availability of digital 3D shapes. However, it is still a challenge to develop tools that allow users to easily produce new 3D shapes, or even to retrieve and process existing ones from online repositories. Current 3D modeling tools often require laborious user interaction via low-level selection and editing commands, while existing search engines for retrieving 3D shapes largely depend on manually entered tags and hand-tuned feature representations which results in unsatisfactory retrieval performance. The PIs goal in this research is to create algorithms based on deep architectures that automatically learn from data how to reliably analyze and synthesize 3D shapes that are optimized for 3D shape processing and synthesis performance (so that, for example, when these shapes are 3D printed they retain desirable physical properties such as reduced mechanical stress). Project outcomes will be released as open source code and will have broad impact not only on computer graphics and computer vision but also on industry, computer-aided design and mechanical engineering pipelines, and architectural engineering software for buildings and indoor environments.

This research will make three major contributions in terms of intellectual merit: 1) Deep architectures and algorithms for learning 3D shape feature representations optimized for retrieval and processing performance; the algorithms will be trained on massive 2D image datasets as well as 3D model repositories, and the learned representations will be used for accurate shape categorization, segmentation, correspondence, style analysis, and texturing. 2) Deep architectures and algorithms for learning to reliably generate new 3D shapes based on intuitive user input, such as sketches and textual descriptions. 3) Algorithms for learning to optimize the underlying geometry of 3D shapes such that they acquire desired physical properties for 3D printing and manufacturing.


MacGregor Smith J.,University of Massachusetts Amherst
Computers and Operations Research | Year: 2011

Finite buffer, single-server queueing systems and networks are difficult to analyze since the length of time a customer spends in the system does not follow the Markovian property. A two-moment approximation schema is developed for the probability distribution of M/G/1/K systems and extended to the analysis of M/G/1/K queueing networks. The general purpose of this paper is to develop a flexible and practical transform-free approach for computing the probability distribution and performance measures of the system as well as identify the underlying properties of these systems. It is shown that for most performance measures, a sigmoid or S-shaped curve with an inflection point at ρ=1 appears as K→∞. This has direct implications for the analysis and optimization of such systems. The performance modelling of the M/G/1/K queueing networks of general topologies along with extensive numerical results accompany the paper along with the linear concave performance measures for these systems. © 2010 Elsevier Ltd. All rights reserved. Source


Krishnan S.S.,Akamai Technologies Inc. | Sitaraman R.K.,University of Massachusetts Amherst
Proceedings of the ACM SIGCOMM Internet Measurement Conference, IMC | Year: 2012

The distribution of videos over the Internet is drastically transforming how media is consumed and monetized. Content providers, such as media outlets and video subscription services, would like to ensure that their videos do not fail, startup quickly, and play without interruptions. In return for their investment in video stream quality, content providers expect less viewer abandonment, more viewer engagement, and a greater fraction of repeat viewers, resulting in greater revenues. The key question for a content provider or a CDN is whether and to what extent changes in video quality can cause changes in viewer behavior. Our work is the first to establish a causal relationship between video quality and viewer behavior, taking a step beyond purely correlational studies. To establish causality, we use Quasi-Experimental Designs, a novel technique adapted from the medical and social sciences. We study the impact of video stream quality on viewer behavior in a scientific data-driven manner by using extensive traces from Akamai's streaming network that include 23 million views from 6.7 million unique viewers. We show that viewers start to abandon a video if it takes more than 2 seconds to start up, with each incremental delay of 1 second resulting in a 5.8%increase in the abandonment rate. Further, we show that a moderate amount of interruptions can decrease the average play time of a viewer by a significant amount. A viewer who experiences a rebuffer delay equal to 1% of the video duration plays 5% less of the video in comparison to a similar viewer who experienced no rebuffering. Finally, we show that a viewer who experienced failure is 2.32% less likely to revisit the same site within a week than a similar viewer who did not experience a failure. © 2012 ACM. Source


Yang Z.,Emory University | Zhang N.,University of Massachusetts Amherst
Medical Care | Year: 2014

BACKGROUND: The obesity rate among the elderly long-term care (LTC) residents in the United States is increasing rapidly. However, there is a paucity of research investigating the burden of obesity on LTC and Medicaid financing. The purpose of this study is to fill the knowledge gap by estimating the burden of overweight and obesity on LTC and Medicaid financing. METHODS: Using nationally representative Cost and Use Files of Medicare Current Beneficiary Survey from 1997 to 2005, we used 2-part model and cohort-based simulation to evaluate the effect of overweight and obesity on LTC days and Medicaid expenditures across the lifespan among the current elderly population. Combining the per capita estimates with 2010 census, we project future aggregate burden of obesity on LTC demand and Medicaid cost among baby boomers. RESULTS: Obesity and related chronic diseases lead to higher probability to enter LTC facility in a younger age, more LTC days before death, and higher lifetime LTC cost reimbursed by Medicaid. However, such effect is only statistically significant among women, not significant among men. At the population level, we project that overweight and obesity will induce 1.3 billion or more LTC patient days and $68 billion or more Medicaid costs (in 2012 value) among baby boomers. CONCLUSIONS: Overweight and obesity among the elderly will bring tremendous burden to LTC providers and Medicaid. Policy makers should keep the burden of obesity on LTC in mind when planning LTC and Medicaid policy reform. Copyright © 2014 by Lippincott Williams & Wilkins. Source


Chasan-Taber L.,University of Massachusetts Amherst
Journal of physical activity & health | Year: 2011

Physical activity during pregnancy is associated with reduced risk of adverse maternal and fetal outcomes. However, the majority of pregnant women are inactive and interventions designed to increase exercise during pregnancy are sparse. We evaluated the feasibility and preliminary efficacy of an exercise intervention among a diverse sample of pregnant women. The B.A.B.Y. (Behaviors Affecting Baby and You) Study is conducted at a large tertiary care facility in Western Massachusetts. We randomized 110 prenatal care patients (60% Hispanic) to an individually tailored 12-week exercise intervention arm (n = 58) or to a health and wellness control arm (n = 52) at mean = 11.9 weeks gestation. Physical activity was assessed via the Pregnancy Physical Activity Questionnaire (PPAQ). After the 12-week intervention, the exercise arm experienced a smaller decrease (-1.0 MET-hrs/wk) in total activity vs. the control arm (-10.0 MET-hrs/wk; P = .03), and a higher increase in sports/exercise (0.9 MET-hrs/wk) vs. the control arm (-0.01 MET-hrs/wk; P = .02). Intervention participants (95%) reported being satisfied with the amount of information received and 86% reported finding the study materials interesting and useful. Findings support the feasibility and preliminary efficacy of a tailored exercise intervention in increasing exercise in a diverse sample of pregnant women. Source


Sela D.A.,University of California at Davis | Sela D.A.,University of Massachusetts Amherst | Mills D.A.,University of California at Davis
American Journal of Clinical Nutrition | Year: 2014

Broadly, nutrigenomics examines the association of exogenous nutrients and molecular responses to maintain homeostasis in an individual. Phenotypic expression profiling, often transcriptomics, has been applied to identify markers and metabolic consequences of suboptimal diet, lifestyle, or both. The decade after the Human Genome Project has been marked with advances in high-throughput analysis of biological polymers and metabolites, prompting a rapid increase in characterization of the profound nature by which our symbiotic microbiota influences human physiology. Although the technology is widely accessible to assess microbiome composition, genetic potential, and global function, nutrigenomics studies often exclude the microbial contribution to host responses to ingested nutritive molecules. Perhaps a hallmark of coevolution, milk provides a dramatic example of a diet that promotes a particular microbial community structure, because the lower infant gastrointestinal tract is often dominated by bifidobacteria that flourish on milk glycans. Systems-level approaches should continue to be applied to examine the microbial communities in the context of their host's dietary habits and metabolic status. In addition, studies of isolated microbiota species should be encouraged to inform clinical studies and interventions as well as community studies. Whereas nutrigenomics research is beginning to account for resident microbiota, the need remains to consistently consider our microscopic partners in the human holobiont. © 2014 American Society for Nutrition. Source


Hatwalne Y.,Raman Research Institute | Muthukumar M.,University of Massachusetts Amherst
Physical Review Letters | Year: 2010

Many achiral polymers crystallize into spherulites with gigantic chirality, as is evident from spectacular images of periodic banding observed in a polarized optical microscope, arising from the twisting of the lamellae making up the spherulites. We present a new mechanism of the spontaneous chiral symmetry breaking, by accounting for topological defects in finite crystalline ribbons made of achiral molecules in equilibrium. We show that disclinations stabilize a twisted helicoidal ribbon, with spontaneous selection of its width and chiral period, which are proportional to each other, as a universal law. © 2010 The American Physical Society. Source


Hoover L.A.,Yale University | Schiffman J.D.,University of Massachusetts Amherst | Elimelech M.,Yale University
Desalination | Year: 2013

Re-engineering the support layers of membranes for forward and pressure retarded osmosis is critical for making these technologies commercially viable. Real-world applications of forward and pressure retarded osmosis, especially those involving natural and waste waters, will require membranes to withstand significant stresses. Therefore, structural changes to the support layer, which are necessary in minimizing internal concentration polarization, must not compromise its critical abilities to resist mechanical stress and provide a suitable surface for the interfacial polymerization of a robust and selective active layer. Electrospinning can provide nanofibers for support layers to potentially overcome the limitations of traditional membrane fabrication techniques in fulfilling these challenging design criteria. In this work, we present the fabrication and evaluation of thin-film composite membranes composed of electrospun polyethylene terephthalate nanofibers, a phase separation formed microporous polysulfone layer, and a polyamide selective layer formed by interfacial polymerization. These membranes have active and support layer transport properties that are suitable for engineered osmosis, with water permeability of 1.13Lm-2h-1bar-1 (3.14×10-7ms-1bar-1), salt permeability of 0.23Lm-2h-1 (6.4×10-8ms-1), and a structural parameter of 651μm. Relevant and easily reproducible tests for membrane resistance to mechanical stress were performed. The use of electrospun fibers in the support layer enhanced membrane resistance to delamination at high cross-flow velocities because the 340nm diameter electrospun fibers enmesh with the microporous polysulfone layer. A broader discussion of the most promising approaches for using electrospun materials to improve membranes for engineered osmosis is provided. © 2012 Elsevier B.V. Source


Remage-Healey L.,University of Massachusetts Amherst
Hormones and Behavior | Year: 2014

Neurons communicate primarily via action potentials that transmit information on the timescale of milliseconds. Neurons also integrate information via alterations in gene transcription and protein translation that are sustained for hours to days after initiation. Positioned between these two signaling timescales are the minute-by-minute actions of neuromodulators. Over the course of minutes, the classical neuromodulators (such as serotonin, dopamine, octopamine, and norepinephrine) can alter and/or stabilize neural circuit patterning as well as behavioral states. Neuromodulators allow many flexible outputs from neural circuits and can encode information content into the firing state of neural networks. The idea that steroid molecules can operate as genuine behavioral neuromodulators - synthesized by and acting within brain circuits on a minute-by-minute timescale - has gained traction in recent years. Evidence for brain steroid synthesis at synaptic terminals has converged with evidence for the rapid actions of brain-derived steroids on neural circuits and behavior. The general principle emerging from this work is that the production of steroid hormones within brain circuits can alter their functional connectivity and shift sensory representations by enhancing their information coding. Steroids produced in the brain can therefore change the information content of neuronal networks to rapidly modulate sensory experience and sensorimotor functions. © 2014 Elsevier Inc. Source


Hof D.,University of Massachusetts Amherst
Proceedings. Biological sciences / The Royal Society | Year: 2013

Rival conspecifics often produce stereotyped sequences of signals as agonistic interactions escalate. Successive signals in sequence are thought to convey increasingly pronounced levels of aggressive motivation. Here, we propose and test a model of aggressive escalation in black-throated blue warblers, presenting subjects with two sequential and increasingly elevated levels of threat. From a speaker outside the territorial boundary, we initiated an interaction (low-threat level), and from a second speaker inside the territory, accompanied by a taxidermic mount, we subsequently simulated a territorial intrusion (escalated threat level). Our two main predictions were that signalling behaviours in response to low-threat boundary playback would predict signalling responses to the escalated within-territory threat, and that these latter signalling behaviours would in turn reliably predict attack. We find clear support for both predictions: (i) specific song types (type II songs) produced early in the simulated interaction, in response to boundary playback, predicted later use of low-amplitude 'soft' song, in response to within-territory playback; and (ii) soft song, in turn, predicted attack of the mount. Unexpectedly, use of the early-stage signal (type II song) itself did not predict attack, despite its apparent role in aggressive escalation. This raises the intriguing question of whether type II song can actually be considered a reliable aggressive signal. Overall, our results provide new empirical insights into how songbirds may use progressive vocal signalling to convey increasing levels of threat. Source


Lu Z.,University of Massachusetts Amherst | Mo H.J.,Anhui Science and Technology University
Astrophysical Journal | Year: 2015

The empirical model of Lu et al. for the relation between star formation rate and halo mass growth is adopted to predict the classical bulge mass (Mcb)-total stellar mass (M∗) relation for central galaxies. The assumption that the supermassive black hole (SMBH) mass (MBH) is directly proportional to the classical bulge mass, with the proportionality given by that for massive galaxies, predicts a MBH-M∗relation that matches well the observed relation for different types of galaxies. In particular, the model reproduces the strong transition at M∗= 1010.5-1011 Me⊙, below which MBH drops rapidly with decreasing M∗. Our model predicts a new sequence at M∗< 1010.5 M⊙, where MBH ∝ M∗but the amplitude is a factor of ∼50 lower than the amplitude of the sequence at M∗> 1011 M⊙. If all SMBHs grow through similar quasar modes with a feedback efficiency of a few percent, then the energy produced in low-mass galaxies at redshift z ≳ 2 can heat the circumgalactic medium up to a specific entropy level that is required to prevent excessive star formation in low-mass dark matter halos. © 2015. The American Astronomical Society. All rights reserved. Source


Hebert D.N.,University of Massachusetts Amherst | Molinari M.,Institute for Research in Biomedicine | Molinari M.,Ecole Polytechnique Federale de Lausanne
Trends in Biochemical Sciences | Year: 2012

Nascent polypeptides entering the endoplasmic reticulum (ER) are covalently modified with pre-assembled oligosaccharides. The terminal glucose and mannose residues are immediately removed after transfer of the oligosaccharide onto newly synthesized polypeptides. This processing determines whether the polypeptide will be retained in the ER, transported along the secretory pathway, or dislocated across the ER membrane for destruction. New avenues of research and some issues of controversy have recently been opened by the discovery that lectin-oligosaccharide interactions stabilize supramolecular complexes between regulators of ER-associated degradation (ERAD). In this Opinion article, we propose a unified model that depicts carbohydrates acting both as flags signaling the fitness of a maturing protein and as docking sites that regulate the assembly and stability of the ERAD machinery. © 2012 Elsevier Ltd. Source


Regional Studies. Per capita rates of entry are commonly used to measure the regional entrepreneurial climate. Yet entry rates vary widely by industry and tend to mirror existing regional specializations. Without controlling for industry mix, factors associated with regional differences in entry may describe the industry base rather than explain variations in entrepreneurial climate. This study finds that although most of the factors commonly associated with the regional entrepreneurial climate remain significant after purging the data of industry-mix effects, others - namely educational attainment, homeownership, university research and development, and unemployment - are contingent upon industry structure. © 2012 © 2012 Regional Studies Association. Source


Lovley D.R.,University of Massachusetts Amherst
Biochemical Society Transactions | Year: 2012

The mechanisms for Fe(III) oxide reduction by Geobacter species are of interest because Geobacter species have been shown to play an important role in Fe(III) oxide reduction in a diversity of environments in which Fe(III) reduction is a geochemically significant process. Geobacter species specifically express pili during growth on Fe(III) oxide compared with growth on soluble chelated Fe(III), and mutants that cannot produce pili are unable to effectively reduce Fe(III) oxide. The pili of Geobacter sulfurreducens are electrically conductive along their length under physiologically relevant conditions and exhibit a metallic-like conductivity similar to that observed previously in synthetic organic metals. Metallic-like conductivity in a biological protein filament is a previously unrecognized mechanism for electron transport that differs significantly from the more well-known biological strategy of electron hopping/tunnelling between closely spaced redox-active proteins. The multihaem c-type cytochrome OmcS is specifically associated with pili and is necessary for Fe(III) oxide reduction. However, multiple lines of evidence, including the metallic-like conductivity of the pili and the fact that OmcS molecules are spaced too far apart for electron hopping/tunnelling, indicate that OmcS is not responsible for long-range electron conduction along the pili. The role of OmcS may be to facilitate electron transfer from the pili to Fe(III) oxide. Long-range electron transport via pili with metallic-like conductivity is a paradigm shift that has important implications not only for Fe(III) oxide reduction, but also for interspecies electron exchange in syntrophic microbial communities as well as microbe-electrode interactions and the emerging field of bioelectronics. ©The Authors Journal compilation ©2012 Biochemical Society. Source


Santangelo C.D.,University of Massachusetts Amherst
Soft Matter | Year: 2013

I consider the shape of a deformed elastic shell. Using the fact that the lowest-energy, small deformations are along infinitesimal isometries of the shell's mid-surface, I describe a class of weakly stretching deformations for thin shells based on the Nambu-Goldstone modes associated with those isometries. The main result is an effective theory to describe the diffuse deformations of thin shells that incorporate stretching and bending energies. The theory recovers previous results for the propagation of a "pinch" on a cylinder. A cone, on the other hand, has two length scales governing the persistence of a pinch: one governing the relaxation of the pinch that scales with thickness as a -1/2 power and one that scales with thickness above which deformations again become isometric. These lengths meet at a critical thickness below which low energy deformations again become nearly isometric. © 2013 The Royal Society of Chemistry. Source


Werner F.,University of Massachusetts Amherst | Werner F.,Kastler-Brossel Laboratory | Castin Y.,Kastler-Brossel Laboratory
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2012

We derive exact general relations between various observables for N spin-1/2 fermions with zero-range or short-range interactions, in continuous space or on a lattice, in two or three dimensions, in an arbitrary external potential. Some of our results generalize known relations between the large-momentum behavior of the momentum distribution, the short-distance behaviors of the pair distribution function and of the one-body density matrix, the norm of the regular part of the wave function, the derivative of the energy with respect to the scattering length or to time, and the interaction energy (in the case of finite-range interactions). The expression relating the energy to a functional of the momentum distribution is also generalized. Moreover, we find expressions (in terms of the regular part of the wave function) for the derivative of the energy with respect to the effective range r e in three dimensions (3D), and to the effective range squared in two dimensions (2D). They express the fact that the leading corrections to the eigenenergies due to a finite-interaction range are linear in the effective range in 3D (and in its square in 2D) with model-independent coefficients. There are subtleties in the validity condition of this conclusion, for the 2D continuous space (where it is saved by factors that are only logarithmically large in the zero-range limit) and for the 3D lattice models (where it applies only for some magic dispersion relations on the lattice that sufficiently weakly break Galilean invariance and that do not have cusps at the border of the first Brillouin zone; an example of such relations is constructed). Furthermore, the subleading short-distance behavior of the pair distribution function and the subleading 1/k6 tail of the momentum distribution are related to ∂E/∂r e [or to ∂E/∂(re2) in 2D]. The second-order derivative of energy with respect to the inverse (or the logarithm in the two-dimensional case) of the scattering length is found to be expressible for any eigenstate in terms of the eigen-wave-function's regular parts; this implies that, at thermal equilibrium, this second-order derivative, taken at fixed entropy, is negative. Applications of the general relations are presented: We compute corrections to exactly solvable two-body and three-body problems and find agreement with available numerics; for the unitary gas in an isotropic harmonic trap, we determine how the finite-1/a and finite-range energy corrections vary within each energy ladder (associated with the SO(2,1) dynamical symmetry) and we deduce the frequency shift and the collapse time of the breathing mode; for the bulk unitary gas, we compare to fixed-node Monte Carlo data, and we estimate the deviation from the Bertsch parameter due to the finite interaction-range in typical experiments. © 2012 American Physical Society. Source


Hepler P.K.,University of Massachusetts Amherst | Winship L.J.,Hampshire College
Journal of Integrative Plant Biology | Year: 2015

Pollen tubes usually exhibit a prominent region at their apex called the "clear zone" because it lacks light refracting amyloplasts. A robust, long clear zone often associates with fast growing pollen tubes, and thus serves as an indicator of pollen tube health. Nevertheless we do not understand how it arises or how it is maintained. Here we review the structure of the clear zone, and attempt to explain the factors that contribute to its formation. While amyloplasts and vacuolar elements are excluded from the clear zone, virtually all other organelles are present including secretory vesicles, mitochondria, Golgi dictyosomes, and the endoplasmic reticulum (ER). Secretory vesicles aggregate into an inverted cone appressed against the apical plasma membrane. ER elements move nearly to the extreme apex, whereas mitochondria and Golgi dictyosomes move less far forward. The cortical actin fringe assumes a central position in the control of clear zone formation and maintenance, given its role in generating cytoplasmic streaming. Other likely factors include the tip-focused calcium gradient, the apical pH gradient, the influx of water, and a host of signaling factors (small G-proteins). We think that the clear zone is an emergent property that depends on the interaction of several factors crucial for polarized growth. © 2014 Institute of Botany, Chinese Academy of Sciences. Source


Debold E.P.,University of Massachusetts Amherst
Medicine and Science in Sports and Exercise | Year: 2012

The cause of muscle fatigue has been studied for more than 100 yr, yet its molecular basis remains poorly understood. Prevailing theories suggest that much of the fatigue-induced loss in force and velocity can be attributed to the inhibitory action of metabolites, principally phosphate (Pi) and hydrogen ions (H, i.e., acidosis), on the contractile proteins, but the precise detail of how this inhibition occurs has been difficult to visualize at the molecular level. However, recent technological developments in the areas of biophysics, molecular biology, and structural biology are enabling researchers to directly observe the function and dysfunction of muscle contractile proteins at the level of a single molecule. In fact, the first direct evidence that high levels of H and Pi inhibit the function of muscle's molecular motor, myosin, has recently been observed in a single molecule laser trap assay. Likewise, advances in structural biology are taking our understanding further, providing detail at the atomic level of how some metabolites might alter the internal motions of myosin and thereby inhibit its ability to generate force and motion. Finally, new insights are also being gained into the indirect role that muscle regulatory proteins troponin (Tn) and tropomyosin (Tn) play in the fatigue process. In vitro studies, incorporating TnTm, suggest that a significant portion of the decreased force and motion during fatigue may be mediated through a disruption of the molecular motions of specific regions within Tn and Tm. These recent advances are providing unprecedented molecular insight into the structure and function of the contractile proteins and, in the process, are reshaping our understanding of the process of fatigue. © 2012 by the American College of Sports Medicine. Source


The crust and upper mantle seismic structure, spanning from the Juan de Fuca and Gorda spreading centers to the Cascade back arc, is imaged with full-wave propagation simulation and a joint inversion of ambient noise and regional earthquake recordings. The spreading centers have anomalously low shear wave velocity beneath the oceanic lithosphere. Around the Cobb axial seamount, we observe a low-velocity anomaly underlying a relatively thin oceanic lithosphere, indicating its influence on the Juan de Fuca ridge. The oceanic Moho is clearly defined by a P velocity increase from 6.3 km/s to 7.5 km/s at about 6 km depth beneath the seafloor. The thickness of the oceanic plates is less than 40 km prior to subduction, and the structure of the oceanic lithosphere varies both along strike and along dip. Farther landward, very low velocity anomalies are observed above the plate interface along the Cascade fore arc, indicative of subducted sediments. ©2016. American Geophysical Union. All Rights Reserved. Source


Wexler L.,University of Massachusetts Amherst
American Journal of Community Psychology | Year: 2011

Community psychology emphasizes the importance of context in the study of people's lives, and culture influences this in profound ways. To develop programs that effectively address diverse communities' problems, it is essential to recognize how Euro-American human service systems are understood and responded to by the many different people being served by them. The article describes how some broadly defined social services-conceptualized and implemented within a Euro-American framework-are ill suited for the everyday realities of Alaska Native villages. The cultural discontinuities are illustrated through ethnographic vignettes. The article concludes with suggestions for developing more culturally-responsive ways to conceive of and do programming for Alaska Native and possibly other Indigenous and minority communities. © 2010 Society for Community Research and Action. Source


Pollard D.,Pennsylvania State University | DeConto R.M.,University of Massachusetts Amherst | Alley R.B.,Pennsylvania State University
Earth and Planetary Science Letters | Year: 2015

Geological data indicate that global mean sea level has fluctuated on 103 to 106 yr time scales during the last ~25 million years, at times reaching 20 m or more above modern. If correct, this implies substantial variations in the size of the East Antarctic Ice Sheet (EAIS). However, most climate and ice sheet models have not been able to simulate significant EAIS retreat from continental size, given that atmospheric CO2 levels were relatively low throughout this period. Here, we use a continental ice sheet model to show that mechanisms based on recent observations and analysis have the potential to resolve this model-data conflict. In response to atmospheric and ocean temperatures typical of past warm periods, floating ice shelves may be drastically reduced or removed completely by increased oceanic melting, and by hydrofracturing due to surface melt draining into crevasses. Ice at deep grounding lines may be weakened by hydrofracturing and reduced buttressing, and may fail structurally if stresses exceed the ice yield strength, producing rapid retreat. Incorporating these mechanisms in our ice-sheet model accelerates the expected collapse of the West Antarctic Ice Sheet to decadal time scales, and also causes retreat into major East Antarctic subglacial basins, producing ~17 m global sea-level rise within a few thousand years. The mechanisms are highly parameterized and should be tested by further process studies. But if accurate, they offer one explanation for past sea-level high stands, and suggest that Antarctica may be more vulnerable to warm climates than in most previous studies. © 2014 The Authors. Source


Chasan-Taber L.,University of Massachusetts Amherst
Advances in nutrition (Bethesda, Md.) | Year: 2012

Pregnancy has been proposed as a critical period for the development of subsequent maternal overweight and/or obesity. Excessive gestational weight gain is, in turn, associated with maternal complications such as cesarean delivery, hypertension, preeclampsia, impaired glucose tolerance, and gestational diabetes mellitus. Although there is substantial evidence that targeting at-risk groups for type 2 diabetes prevention is effective if lifestyle changes are made, relatively little attention has been paid to the prevention of excessive gestational weight gain and impaired glucose tolerance during pregnancy. Latinos are the largest minority group in the United States, with the highest birth and immigration rates of any minority group and are disproportionately affected by overweight and obesity. However, due to cultural factors, socioeconomic factors, and language barriers, Latinos have had limited access to public health interventions that promote healthy lifestyles. Therefore, the objective of this article is to review the scientific evidence regarding the association between physical activity, dietary behaviors, and gestational weight gain and impaired glucose tolerance among Latinas. A second objective is to discuss how lifestyle interventions including weight management through diet and exercise could be successful in reducing the risk of excessive gestational weight gain and gestational diabetes mellitus. Finally, recommendations are provided for future lifestyle intervention programs in this population with a focus on translation and dissemination of research findings. Source


Ramasubramaniam A.,University of Massachusetts Amherst
Physical Review B - Condensed Matter and Materials Physics | Year: 2012

Quasiparticle band structures and optical properties of MoS 2, MoSe 2, MoTe 2, WS 2, and WSe 2 monolayers are studied using the GW approximation in conjunction with the Bethe-Salpeter equation (BSE). The inclusion of two-particle excitations in the BSE approach reveals the presence of two strongly bound excitons (A and B) below the quasiparticle absorption onset arising from vertical transitions between a spin-orbit-split valence band and the conduction band at the K point of the Brillouin zone. The transition energies for monolayer MoS 2, in particular, are shown to be in excellent agreement with available absorption and photoluminescence measurements. Excitation energies for the remaining monolayers are predicted to lie in the range of 1-2 eV. Systematic trends are identified for quasiparticle band gaps, transition energies, and exciton binding energies within as well as across the Mo and W families of dichalcogenides. Overall, the results suggest that quantum confinement of carriers within monolayers can be exploited in conjunction with chemical composition to tune the optoelectronic properties of layered transition-metal dichalcogenides at the nanoscale. © 2012 American Physical Society. Source


Edzwald J.K.,University of Massachusetts Amherst | Haarhoff J.,University of Johannesburg
Water Research | Year: 2011

The paper addresses the effects of salinity and temperature on the chemistry of important parameters affecting coagulation pretreatment including the ion product of water, acid-base chemistry, dissolved metal speciation, and precipitation reactions for aluminum and iron coagulants. The ion product of seawater is greater than for freshwaters and affects chemical hydrolysis and metal-hydroxide solubility reactions. Inorganic carbon is the main cause of seawater alkalinity and buffer intensity but borate B(OH)41- also contributes. Buffer intensity is an important parameter in assessing coagulation pH adjustment. Mineral particles are relatively unstable in seawater from electrical double layer compression, and when present these particles are easily coagulated. Algal-particle stability is affected by steric effects and algal motility. Dissolved natural organic matter from algae and humic substances causes fouling of RO membranes and pretreatment removal is essential. Aluminum coagulants are not recommended, and not used, because they are too soluble in seawater. Ferric coagulants are preferred and used. The equilibrium solubility of Fe with amorphous ferric hydroxide in seawater is low over a wide range of pH and temperature conditions. Ferric chloride dosing guidelines are presented for various raw seawater quality characteristics. The effect of pH on coagulant dose and the role of buffer intensity are addressed. A dual coagulation strategy is recommended for treating seawater with moderate to high concentrations of algae or seawater with humic matter. This involves a low and constant dose with high charge-density cationic polymers using Fe as the main coagulant where it is varied in response to raw water quality changes. © 2011 Elsevier Ltd. Source


Seyrek E.,French National Center for Scientific Research | Dubin P.,University of Massachusetts Amherst
Advances in Colloid and Interface Science | Year: 2010

One of the barriers to understanding structure-property relations for glycosaminoglycans has been the lack of constructive interplay between the principles and methodologies of the life sciences (molecular biology, biochemistry and cell biology) and the physical sciences, particularly in the field of polyelectrolytes. To address this, we first review the similarities and differences between the physicochemical properties of GAGs and other statistical chain polyelectrolytes of both natural and abioitic origin. Since the biofunctionality and regulation of the structures of GAGs is intimately connected with interactions with their cognate proteins, we particularly compare and contrast aspects of protein binding, i.e. effects of both GAGs and other polyelectrolytes on protein stability, protein aggregation and phase behavior. The protein binding affinities and their dependences on pH and ionic strength for the two groups are discussed not only in terms of observable differences, but also with regard to contrasting descriptions of the bound state and the role of electrostatics. We conclude that early studies of the heparin-Antithromin system, proceeding to a large extent through the methods and models of protein chemistry and drug discovery, established not only many enabling precedents but also constraining paradigms. Current studies on heparan sulfate and chondroitin sulfate seem to reflect a more ecumenical view likely to be more compatible with concepts from physical and polymer chemistry. © 2010 Elsevier B.V. All rights reserved. Source


Law K.J.H.,University of Warwick | Kevrekidis P.G.,University of Massachusetts Amherst | Tuckerman L.S.,University of Paris Descartes
Physical Review Letters | Year: 2010

We report the numerical realization of robust two-component structures in 2D and 3D Bose-Einstein condensates with nontrivial topological charge in one component. We identify a stable symbiotic state in which a higher-dimensional bright soliton exists even in a homogeneous setting with defocusing interactions, due to the effective potential created by a stable vortex in the other component. The resulting vortex-bright-solitons, generalizations of the recently experimentally observed dark-bright solitons, are found to be very robust both in the homogeneous medium and in the presence of external confinement. © 2010 The American Physical Society. Source


Maresca T.J.,University of Massachusetts Amherst
Current Biology | Year: 2013

Localization of the histone H3 variant Cse4 (CENP-A) at the ∼125 base pair point centromere in budding yeast directs assembly of a kinetochore that binds one microtubule. Recent work suggests there is more Cse4 at point centromeres than originally thought. © 2013 Elsevier Ltd. Source


Wexler L.M.,University of Massachusetts Amherst
American Journal of Public Health | Year: 2012

Indigenous communities have significantly higher rates of suicide than non- Native communities in North America. Prevention and intervention efforts have failed to redress this disparity. One explanation is that these efforts are culturally incongruent for Native communities. Four prevalent assumptions that underpin professional suicide prevention may conflict with local indigenous understandings about suicide. Our experiences in indigenous communities led us to question assumptions that are routinely endorsed and promoted in suicide prevention programs and interventions. By raising questions about the universal relevance of these assumptions, we hope to stimulate exchange and inquiry into the character of this devastating public health challenge and to aid the development of culturally appropriate interventions in cross-cultural contexts. Source


Stranlund J.K.,University of Massachusetts Amherst
Environmental and Resource Economics | Year: 2015

This note examines the effects of correlated uncertainty between abatement costs and pollution damage on hybrid emissions control policies. In particular, I show how correlated uncertainty affects the structure and performance of control policies that combine permit trading with price controls. Moreover, I show how correlated uncertainty affects the choice between a simple emissions tax versus a hybrid policy. Under correlated uncertainty, constant marginal damage is no longer necessary or sufficient for a tax to be an optimal policy. © 2014, Springer Science+Business Media Dordrecht. Source


Marchesi M.,University of Massachusetts Amherst
Anthropology and Medicine | Year: 2012

In national and international discourses, Italians are often represented as a greying population failing to reproduce itself. Italian women are targeted for their very low birth rates, while migrant women are scrutinized for their 'excessive' fertility and abortion rates. These demographic concerns over differential reproduction reflect 'replacement anxiety' about the belowreplacement rates of Italians and the replacement of Italians by immigrants. Demographic anxieties coalesce with the intensifying of Catholic 'vitapolitics' manifesting in the paradox of pro-natalist interventions coexisting with the curtailment of fertility-enhancing reproductive technologies. The children of migrants emerge in some population discourses as a threat rather than a contribution to the reproduction of the nation. Drawing on multi-sited ethnographic research in Milan, this paper examines how reproduction in contemporary Italy has emerged as a contested social, political, and moral issue that invests Italian and migrant women in different ways, engendering different forms and terms of resistance and contestation. On what terms are subjects governed and called upon to govern themselves to be more 'rational' and 'responsible' reproducers of the nation? What subjectivities and local responses are engendered by the politics of reproduction in Italy? As different rationalities and notions of responsible reproduction circulate, ethnographic research sheds light on how anxieties over low birth rates are reappropriated and redeployed against the state, suggesting that subjects are not so easily governable by population and reproductive discourses. This research contributes to the literature on critical demography and the politics of reproduction and migration in the new Europe. © 2012 Taylor & Francis. Source


Baker E.,University of Massachusetts Amherst | Keisler J.M.,University of Massachusetts Boston
Energy | Year: 2011

In this paper we structure, obtain and analyze results of an expert elicitation on the relationship between U. S. government Research & Development funding and the likelihood of achieving advances in cellulosic biofuel technologies. While there was disagreement among the experts on each of the technologies, the patterns of disagreement suggest several distinct strategies. Selective Thermal Processing appears to be the most promising path, with the main question being how much funding is required to achieve success. Thus, a staged investment in this path looks promising. With respect to gasification, there remains fundamental disagreement over whether success is possible even at higher funding levels. Thus, basic research into the viability of the path makes sense. The Hydrolysis path induced the widest range of responses from the experts, indicating there may be value in collecting more information on this technology. © 2010 Elsevier Ltd. Source


Zilberberg M.D.,University of Massachusetts Amherst | Zilberberg M.D.,EviMed Research Group | Shorr A.F.,Washington Hospital Center
Clinical Infectious Diseases | Year: 2010

The Clinical Pulmonary Infection Score (CPIS) was developed to serve as a surrogate tool to facilitate the diagnosis of ventilator-associated pneumonia (VAP). The CPIS is calculated on the basis of points assigned for various signs and symptoms of pneumonia (eg, fever and extent of oxygenation impairment). Although some studies suggest that a CPIS>6 may correlate with VAP, most studies indicate that the CPIS has limited sensitivity and specificity. In addition, no well-done studies validate the CPIS in either acute lung injury or trauma. The interobserver variability in CPIS calculation remains substantial, suggesting that this cannot be routinely used across multiple centers to support the conduct of randomized clinical trials. Changes in the CPIS may correlate with outcomes in VAP, but it appears that the ratio of partial pressure of arterial oxygen to the fraction of inspired oxygen is a more important marker for outcomes than the CPIS. At present, the CPIS has a limited role both clinically and as a research tool. © 2010 by the Infectious Diseases Society of America. All rights reserved. Source


Hall D.M.,University of Massachusetts Amherst
Nature Materials | Year: 2016

In assemblies, the geometric frustration of a locally preferred packing motif leads to anomalous behaviours, from self-limiting growth to defects in the ground state. Here, we demonstrate that geometric frustration selects the equilibrium morphology of cohesive bundles of chiral filaments, an assembly motif critical to a broad range of biological and synthetic nanomaterials. Frustration of inter-filament spacing leads to optimal shapes of self-twisting bundles that break the symmetries of packing and of the underlying inter-filament forces, paralleling a morphological instability in spherical two-dimensional crystals. Equilibrium bundle morphology is controlled by a parameter that characterizes the relative costs of filament bending and the straining of cohesive bonds between filaments. This parameter delineates the boundaries between stable, isotropic cylindrical bundles and anisotropic, twisted-tape bundles. We also show how the mechanical and interaction properties of constituent amyloid fibrils may be extracted from the mesoscale dimensions of the anisotropic bundles that they form. © 2016 Nature Publishing Group Source


Krishna C.M.,University of Massachusetts Amherst
ACM Computing Surveys | Year: 2014

Real-time systems are one of the most important applications of computers, both in commercial terms and in terms of social impact. Increasingly, real-time computers are used to control life-critical applications and need to meet stringent reliability conditions. Since the reliability of a real-time system is related to the probability of meeting its hard deadlines, these reliability requirements translate to the need to meet critical task deadlines with a very high probability. We survey the problem of how to schedule tasks in such a way that deadlines continue to be met despite processor (permanent or transient) or software failure. © 2014 ACM. Source


DeConto R.M.,University of Massachusetts Amherst | Pollard D.,Pennsylvania State University
Nature | Year: 2016

Polar temperatures over the last several million years have, at times, been slightly warmer than today, yet global mean sea level has been 6-9 metres higher as recently as the Last Interglacial (130,000 to 115,000 years ago) and possibly higher during the Pliocene epoch (about three million years ago). In both cases the Antarctic ice sheet has been implicated as the primary contributor, hinting at its future vulnerability. Here we use a model coupling ice sheet and climate dynamics - including previously underappreciated processes linking atmospheric warming with hydrofracturing of buttressing ice shelves and structural collapse of marine-terminating ice cliffs - that is calibrated against Pliocene and Last Interglacial sea-level estimates and applied to future greenhouse gas emission scenarios. Antarctica has the potential to contribute more than a metre of sea-level rise by 2100 and more than 15 metres by 2500, if emissions continue unabated. In this case atmospheric warming will soon become the dominant driver of ice loss, but prolonged ocean warming will delay its recovery for thousands of years. © 2016 Macmillan Publishers Limited. All rights reserved. Source


McClements D.J.,University of Massachusetts Amherst
Expert Opinion on Drug Delivery | Year: 2013

Introduction: The oral bioavailability of many lipophilic bioactives, such as pharmaceuticals and nutraceuticals, is relatively low due to their poor solubility, permeability and/or chemical stability within the human gastrointestinal tract (GIT). The oral bioavailability of lipophilic bioactives can be improved by designing food matrices that control their release, solubilization, transport and absorption within the GIT. Areas covered: This article discusses the challenges associated with delivering lipophilic bioactive components, the impact of food composition and structure on oral bioavailability and the design of functional and medical foods for improving the oral bioavailability of lipophilic bioactives. Expert opinion: Food-based delivery systems can be used to improve the oral bioavailability of lipophilic bioactives. There are a number of potential advantages to delivering lipophilic bioactives using functional or medical foods: greater compliance than conventional delivery forms; increased bioavailability and efficacy; and reduced variability in biological effects. However, food matrices are structurally complex multicomponent materials and research is still needed to identify optimum structures and compositions for particular bioactives. © Informa UK, Ltd. Source


Podos J.,University of Massachusetts Amherst
Philosophical Transactions of the Royal Society B: Biological Sciences | Year: 2010

Populations with multiple morphological or behavioural types provide unique opportunities for studying the causes and consequences of evolutionary diversification. A population of the medium ground finch (Geospiza fortis) at El Garrapatero on Santa Cruz Island, Galápagos, features two beak size morphs. These morphs produce acoustically distinctive songs, are subject to disruptive selection and mate assortatively by morph. The main goal of the present study was to assess whether finches from this population are able to use song as a cue for morph discrimination. A secondary goal of this study was to evaluate whether birds from this population discriminate songs of their own locality versus another St Cruz locality, Borrero Bay, approximately 24 km to the NW. I presented territorial males with playback of songs of their own morph, of the other morph, and of males from Borrero Bay. Males responded more strongly to same-morph than to other-morph playbacks, showing significantly shorter latencies to flight, higher flight rates and closer approaches to the playback speaker. By contrast, I found only minor effects of locality on responsiveness. Evidence for morph discrimination via acoustic cues supports the hypothesis that song can serve as a behavioural mechanism for assortative mating and sympatric evolutionary divergence. ©2010 The Royal Society. Source


Weinberg M.D.,University of Massachusetts Amherst
Monthly Notices of the Royal Astronomical Society | Year: 2014

We describe a hybrid Direct Simulation Monte Carlo (DSMC) code for simultaneously solving the collisional Boltzmann equation for gas and the collisional Boltzmann equation for stars and dark matter for problems important to galaxy evolution. This project is motivated by the need to understand the controlling dynamics at interfaces between gases of widely differing densities and temperature, i.e. multiphase media. While more expensive than hydrodynamics, the kinetic approach does not suffer from discontinuities and it applies when the continuum limit does not, such as in the collapse of galaxy clusters and at the interface between coronal halo gas and a thin neutral gas layer. Finally, the momentum flux is carried, self-consistently, by particles and this approach explicitly resolves and thereby 'captures' shocks.The DSMC method splits the solution into two pieces: (1) the evolution of the phase-space flow without collisions and (2) the evolution governed the collision term alone withoutphase-space flow. This splitting approach makes DSMC an ideal match to existing particle-based n-body codes. If the mean-free path becomes very small compared to any scale of interest, the method abandons simulated particle collisions and simply adopts the relaxed solution in each interaction cell consistent with the overall energy and momentum fluxes. This is functionally equivalent to solving the Navier-Stokes equations on a mesh. Our implementation is tested using the Sod shock-tube problem and the non-linear development of a Kelvin-Helmholtz unstable shear layer. © 2014 The Author Published by Oxford University Press on behalf of the Royal Astronomical Society. Source


Weinberg M.D.,University of Massachusetts Amherst
Monthly Notices of the Royal Astronomical Society | Year: 2014

We use the Direct Simulation Monte Carlo method combined with an N-body code to study the dynamics of the interaction between a gas-rich spiral galaxy and intracluster or intragroup medium, often known as the ram pressure scenario. The advantage of this gas kinetic approach over traditional hydrodynamics is explicit treatment of the interface between the hot and cold, dense and rarefied media typical of astrophysical flows and the explicit conservation of energy and momentum and the interface. This approach yields some new physical insight. Owing to the shock and backward wave that forms at the point intracluster medium (ICM)-interstellar medium (ISM) contact, ICM gas is compressed, heated and slowed. The shock morphology is Mach disc like. In the outer galaxy, the hot turbulent post-shock gas flows around the galaxy disc while heating and ablating the initially cool disc gas. The outer gas and angular momentum are lost to the flow. In the inner galaxy, the hot gas pressurizes the neutral ISM gas causing a strong two-phase instability. As a result, the momentum of the wind is no longer impulsively communicated to the cold gas as assumed in the Gunn-Gott formula, but oozes through the porous disc, transferring its linear momentum to the disc en masse. The escaping gas mixture has a net positive angular momentum and forms a slowly rotating sheath. The shear flow caused by the post-shock ICM flowing through the porous multiphase ISM creates a strong Kelvin-Helmholtz instability in the disc that results in Cartwheel-like ring and spoke morphology. © 2014 The Author Published by Oxford University Press on behalf of the Royal Astronomical Society. Source


Huber K.L.,University of Massachusetts Amherst
Biopolymers | Year: 2012

Caspases comprise a family of dimeric cysteine proteases that control apoptotic programmed cell death and are therefore critical in both organismal development and disease. Specific inhibition of individual caspases has been repeatedly attempted, but has not yet been attained. Caspase-9 is an upstream or initiator caspase that is regulated differently from all other caspases, as interaction with natural inhibitor X-linked inhibitor of apoptosis protein (XIAP)-baculovirus inhibitory repeat 3 (BIR3) occurs at the dimer interface maintaining caspase-9 in an inactive monomeric state. One route to caspase-9-specific inhibition is to mimic this interaction, which has been localized to the α5 helix of XIAP-BIR3. We have developed three types of stabilized peptides derived from the α5 helix, using incorporation of aminoisobutyric acid, the avian pancreatic polypeptide (aPP)-scaffold or aliphatic staples. The stabilized peptides are helical in solution and achieve up to 32 μM inhibition, indicating that this allosteric site at the caspase-9 dimerization interface is regulatable with low-molecular weight synthetic ligands and is thus a druggable site. The most potent peptides against caspase-9 activity are the aPP-scaffolded peptides. Other caspases, which are not regulated by dimerization, should not be inactivated by these peptides. Given that all of the peptides attain helical structures but cannot recapitulate the high-affinity inhibition of the intact BIR3 domain, it has become clear that interactions of caspase-9 with the BIR3 exosite are essential for high-affinity binding. These results explain why the full XIAP-BIR3 domain is required for maximal inhibition and suggest a path forward for achieving allosteric inhibition at the dimerization interface using peptides or small molecules. Copyright © 2012 Wiley Periodicals, Inc. Source


White S.J.,University of Leicester | Staub A.,University of Massachusetts Amherst
Journal of Experimental Psychology: Human Perception and Performance | Year: 2012

Participants' eye movements were recorded as they read single sentences presented normally, presented entirely in faint text, or presented normally except for a single faint word. Fixations were longer when the entire sentence was faint than when the sentence was presented normally. In addition, fixations were much longer on a single faint word embedded in normal text, compared to when the entire sentence was faint. The primary aim of the study was to examine the influence of stimulus quality on the distribution of fixation durations. Ex-Gaussian fitting revealed that stimulus quality affected the mean of the Normal component, but in contrast to results from single-word tasks (Plourde & Besner, 1997), stimulus quality did not affect the exponential component, regardless of whether one or all words were faint. The results also contrast with the finding (Staub, White, Drieghe, Hollway, & Rayner, 2010) that the word frequency effect on fixation durations is an effect on both of the critical distributional parameters. These findings are argued to have implications for the interpretation of the role of stimulus quality in word recognition, and for models of eye movement control in reading. © 2011 American Psychological Association. Source


Heyer M.H.,University of Massachusetts Amherst | Brunt C.M.,University of Exeter
Monthly Notices of the Royal Astronomical Society | Year: 2012

Magnetically aligned velocity anisotropy over varying physical conditions and environments within the Taurus molecular cloud is evaluated from analysis of wide field spectroscopic imaging of 12CO and 13CO J= 1-0 emission. Such anisotropy is a result of magnetohydrodynamic turbulence in the strong magnetic field regime and provides an indirect measure of the role of magnetic fields upon the gas. Velocity anisotropy aligned with the local, projected mean magnetic field direction is limited to fields with low surface brightness 12CO emission corresponding to regions of low visual extinction and, presumably, low gas volume density. The more optically thin 13CO J= 1-0 emission shows little evidence for velocity anisotropy. We compare our results with computational simulations with varying degrees of magnetic field strength and Alfvénic Mach numbers. In the diffuse, molecular envelope of the cloud, a strong magnetic field and sub-Alfvénic turbulent motions are inferred. Super-Alfvénic motions are present within the high column density filaments of the Taurus cloud. From this trans-Alfvénic flow, we constrain the scaling exponent, κ, of the magnetic field density relation (B~n κ) to be near zero as expected for ambipolar diffusion or material loading of magnetic flux tubes. © 2011 The Authors Monthly Notices of the Royal Astronomical Society © 2011 RAS. Source


Seaman S.J.,University of Massachusetts Amherst
American Mineralogist | Year: 2013

The effects of water concentration and degassing history on the development of spherulites and flow banding were examined in three middle Tertiary rhyolitic lava flows from the Atascosa Mountains of southern Arizona. The Hell's Gate lava flow and the Atascosa lava flow host spherulites of strongly contrasting texture, and neither are flow banded. The Sycamore Canyon lava flow is a flow-banded rhyolite that hosts two populations of spherulites. Spherulites in the Hell's Gate lava flow consist of two to four generations of bladed radiating alkali feldspar crystals that increase in water concentration along their length. Needle-like radiating feldspar crystals in spherulites in the Atascosa and Sycamore Canyon lava flows are in some cases punctuated by concentric rinds of glass that are reservoirs for water rejected by the feldspar crystals. The differences in spherulite crystal morphology between the Sycamore Canyon and Atasocosa flows (both needle-like) and the Hell's Gate flow (bladed) may reflect a more rapid cooling rate of the Sycamore Canyon and Atascosa flows. Thick gray flow bands in the Sycamore Canyon lava flow host higher water concentrations than thin orange flow bands, suggesting that flow bands are zones of greater and lesser volatile concentration, deformed by stretching of the flowing magma. Temperature was uniform across the light and dark flow bands of the Sycamore Canyon flow, indicating that water concentration, one of the variables that controls diffusion coefficients, rather than temperature, controlled spherulite size in this case. Phenocrysts in the Hell's Gate lava flow are strongly resorbed, probably as a result of magma ascent along a near-adiabatic gradient that resulted in exsolution of water from the melt, and subsequent dissolution of existing quartz phenocrysts by the water-rich melt. Resumption of crystallization of anhydrous phases such as quartz and feldspar would have further enriched the melt in water, facilitating the growth of spherulites. Spherulites in two of the lava flows (Sycamore Canyon and Hell's Gate) increase in water concentration from core to rim, as would be expected in spherulites growing in melt enriched in water rejected by the growing feldspar crystals. Spherulites in the Atascosa rhyolite flow decrease slightly in water concentration from core to rim, possibly because the magma degassed during spherulite growth. Calculation of water concentration profiles in spherulites from all three rhyolite flows on the basis of Rayleigh fractionation of water between sanidine and rhyolitic melt shows that the very high water concentrations in spherulites (typically >0.6 × water concentration in surrounding glass) cannot be accounted for by Rayleigh fractionation. Instead it is likely that sanidine incorporated water as fluid inclusions and/or as water clusters during rapid crystal growth. Water concentration profiles in the glass surrounding spherulites do not preserve the high concentration zone at the spherulite boundary that has been observed in younger lava flows, so that spherulite growth rates cannot be calculated on the basis of mass-balance calculations of distribution of water during spherulite growth. Rather, the water concentration profile in the surrounding glass is a half plateau, the height of which is approximately equivalent to the far-field water concentration in the surrounding glass, indicating that water that accumulated at the spherulite/magma boundary diffused sufficiently rapidly to equilibrate with the surrounding magma as the lava flow cooled. Source


Stoffolano Jr. J.G.,University of Massachusetts Amherst | Haselton A.T.,State University of New York at New Paltz
Annual Review of Entomology | Year: 2013

The diverticulated crop is a unique and overlooked foregut organ in the Diptera that affects many physiological and behavioral functions. Historically, the crop was viewed simply as a reservoir for excess nutrients. The crop lobes and crop duct form an elaborate sphincter and pump system that moves stored nutrients to the crop lobes, oral cavity, and the midgut. The storage capacity of the crop lobes is significant when filled maximally and supplies sufficient carbohydrates to sustain prolonged activity and flight, and adequate protein and lipids to facilitate reproductive events. Crop emptying is under complex neuroendocrine and neural control and may be influenced by multiple neuromessengers, such as serotonin and dromyosuppressin. The crop lobes also serve as a site for the initial mixing of enzymes from the salivary glands and antimicrobials from the labellar glands with ingested food. These food-processing functions are associated with behaviors unique to dipterans, such as regurgitation (or bubbling), nuptial gift giving, and substrate droplet deposition or trap-lining. © 2013 by Annual Reviews. All rights reserved. Source


Robert P.,University of Massachusetts Amherst
International Journal of Health Services | Year: 2012

In December 2010, the United Nations Food and Agriculture Organization's Food Price Index surpassed its previous peak of June 2008, and prices remained at this level through September 2011. This pattern is creating justified fears of a renewal or intensification of the global food crisis. This paper reviews arguments and evidence to inform debates on how to regulate commodity futures markets in the face of such price volatility and sustained high prices. We focus on the relationship between market liquidity and price patterns in asset markets in general and in commodities futures markets in particular, as well as the relationship between spot and futures market prices for food. We find strong evidence supporting the need to limit huge increases in trading volume on futures markets through regulations. We find that arguments opposing regulation are not supported. We find no support for the claim that liquidity in futures markets stabilizes prices at "fundamental" values or that spot market prices are free of any significant influence from futures markets. Given these results, the most appropriate position for regulators is precautionary: they should enact and enforce policies capable of effectively dampening excessive speculative trading on the commodities markets for food. © 2012, Baywood Publishing Co., Inc. Source


Lackner M.A.,University of Massachusetts Amherst | Rotea M.A.,University of Texas at Dallas
Wind Energy | Year: 2011

The application of control techniques to offshore wind turbines has the potential to significantly improve the structural response of these systems. A new simulation tool is developed that can be utilized to model passive, semi-active and active structural control systems in wind turbines. Two independent, single degree of freedom (DOF) tuned mass- damper (TMD) devices are incorporated into a modified version of the aero-elastic code FAST (Fatigue, Aerodynamics, Structures and Turbulence). The TMDs are located in the nacelle of the turbine model, with one TMD translating in the fore-aft direction, and the other in the side-side direction. The equations of motion of the TMDs are incorporated into the source code of FAST, yielding a more realistic system for modeling structural control in wind turbines than has previously been modeled. The stiffness, damping and commanded force of each TMD are controllable through the FAST-Simulink interface, and so idealizations of semi-active and active control approaches can be implemented. A parametric study is performed to determine the optimal parameters of a passive single DOF, fore-aft, TMD system in both a barge-type and monopile support structure. The wind turbine models equipped with TMDs are then simulated and the performance of these new systems is evaluated. The results indicate that passive control approaches can be used to improve the structural response of offshore wind turbines. The results also demonstrate the potential for active control approaches. © 2010 John Wiley & Sons, Ltd. Source


McClements D.J.,University of Massachusetts Amherst
Soft Matter | Year: 2011

There is increasing interest within the food, beverage and pharmaceutical industries in utilizing edible nanoemulsions to encapsulate, protect and deliver lipophilic functional components, such as oil-soluble flavors, vitamins, preservatives, nutraceuticals, and drugs. There are a number of potential advantages of using nanoemulsions rather than conventional emulsions for this purpose: they can greatly increase the bioavailability of lipophilic substances; they scatter light weakly and so can be incorporated into optically transparent products; they can be used to modulate the product texture; and they have a high stability to particle aggregation and gravitational separation. On the other hand, there may also be some risks associated with the oral ingestion of nanoemulsions, such as their ability to change the biological fate of bioactive components within the gastrointestinal tract and the potential toxicity of some of the components used in their fabrication. This tutorial review provides an overview of the current status of nanoemulsion fabrication, properties, and applications with special emphasis on systems suitable for utilization within the food industry. © 2011 The Royal Society of Chemistry. Source


Castin Y.,Kastler-Brossel Laboratory | Werner F.,University of Massachusetts Amherst
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2011

Experimental progress in the study of strongly interacting ultracold atoms has recently allowed the observation of Efimov trimers. We study theoretically a nonconventional observable for these trimer states, which may be accessed experimentally, the momentum distribution n(k) of the constitutive bosonic particles. The large momentum part of the distribution is particularly intriguing: In addition to the expected 1/k4 tail associated with contact interactions, it exhibits a subleading tail 1/k5 which is a hallmark of Efimov physics and leads to a breakdown of a previously proposed expression of the energy as a functional of the momentum distribution. © 2011 American Physical Society. Source


Glass L.,McGill University | Siegelmann H.T.,University of Massachusetts Amherst
Current Opinion in Genetics and Development | Year: 2010

Logical models provide insight about key control elements of biological networks. Based solely on the logical structure, we can determine state transition diagrams that give the allowed possible transitions in a coarse grained phase space. Attracting pathways and stable nodes in the state transition diagram correspond to robust attractors that would be found in several different types of dynamical systems that have the same logical structure. Attracting nodes in the state transition diagram correspond to stable steady states. Furthermore, the sequence of logical states appearing in biological networks with robust attracting pathways would be expected to appear also in Boolean networks, asynchronous switching networks, and differential equations having the same underlying structure. This provides a basis for investigating naturally occurring and synthetic systems, both to predict the dynamics if the structure is known, and to determine the structure if the transitions are known. © 2010 Elsevier Ltd. Source


Haas P.M.,University of Massachusetts Amherst
Global Policy | Year: 2012

This article assesses the prospects for advancing to a green economy at Rio Plus 20 through the perspective of international political economy writings on economic transformations and regime governance. In order to achieve robust investment in revolutionary new technologies a clear international political project is required that provides a common purpose, clear regulatory and legal rules, and formal organisational efforts for resource mobilisation, compensation of losers, and enforcement. It concludes with an appraisal of efforts underway to create the political foundation for a green economy, suggesting the creation of a new international organization for green technology innovation, and assigning the United Nations Environment Programme (UNEP) to environmental science assessment. © 2012 London School of Economics and Political Science and John Wiley & Sons Ltd. Source


Visconti P.E.,University of Massachusetts Amherst | Florman H.M.,University of Massachusetts Medical School
Science Signaling | Year: 2010

A model of the early events of mammalian fertilization has emerged during the past 30 years. However, studies during the past decade have used newly available mouse models to readdress these processes. Here, we will consider these new data in light of the existing model and point to areas of reconciliation and of controversy. Source


The source area of the ~16 Ma Columbia River flood basalt eruptions originated beneath the Wallowa Mountains in northeast Oregon, with a distinct circular pattern of topographic uplift. Teleseismic receiver functions reveal two layers between latitude 45.5° and 46.5° beneath north of the Wallowas, one at 25 km depth and the other one at 45 km depth. A new full-wave ambient noise tomography model shows a circular anomaly, which is seismically fast in the upper crust and slow from lower crust to uppermost mantle in comparison with the surroundings, coincident with the circular pattern of the Wallowas. The seismic structures suggest that delamination of the Farallon lithosphere initiated the basalt eruptions and, consequently, modified the lowermost crust, forming a new shallow Moho. The Farallon slab is probably detached directly beneath the Wallowas while being maintained at the northern edge of the Wallowas, corresponding to the deeper interface. Key Points Teleseismic receiver functions are highly complex and azimuthally varying Bifurcating Moho is detected north of the Columbia River basalt eruptions Lithosphere delamination triggered the basalt eruptions and modified the lower crust. © 2015. American Geophysical Union. All Rights Reserved. Source


Gillespie S.,University of Massachusetts Amherst
Ecological Entomology | Year: 2010

Bumblebees are important pollinators in North America and are attacked by a range of parasites that impact their fitness; however, few studies have investigated the extent or causes of parasitism in North America.This study used a 2-year multi-site survey of bumblebee parasitism to ask: (i) how common are parasitoid conopid flies and the internal parasites Crithidia bombi and Nosema bombi in Massachusetts; and (ii) what factors are correlated with parasitism?Infection rates by all three parasites were higher in this study than previously documented in North America. Overall, conopids infected 0-73% of bees in each sample, C. bombi infected 0-82% of bees, and N. bombi infected 0-32%.Conopid flies infected female bees more than males and intermediate-sized bees more than large or small bees. Crithidia bombi infection rates were higher in certain bee species and sites, and exhibited a unimodal pattern of prevalence over time. Nosema bombi parasitism was higher in male than female bees.Infection by N. bombi in two rare bumblebee species was higher than expected based on parasitism rates of common bee species but C. bombi infection was lower.If high prevalence of N. bombi in these bumblebee species is common, parasitism may be a potential cause of their decline.Given the documented effects of these parasites, the high levels of infection may affect bee populations in Massachusetts and threaten the stability of their valuable ecosystem services. © 2010 The Author. Ecological Entomology © 2010 The Royal Entomological Society. Source


Cohn A.W.,University of Washington | Kittilstved K.R.,University of Washington | Kittilstved K.R.,University of Massachusetts Amherst | Gamelin D.R.,University of Washington
Journal of the American Chemical Society | Year: 2012

Colloidal reduced ZnO nanocrystals are potent reductants for one-electron or multielectron redox chemistry, with reduction potentials tunable via the quantum confinement effect. Other methods for tuning the redox potentials of these unusual reagents are desired. Here, we describe synthesis and characterization of a series of colloidal Zn 1-xMg xO and Zn 0.98-xMg xMn 0.02O nanocrystals in which Mg 2+ substitution is used to tune the nanocrystal reduction potential. The effect of Mg 2+ doping on the band-edge potentials of ZnO was investigated using electronic absorption, photoluminescence, and magnetic circular dichroism spectroscopies. Mg 2+ incorporation widens the ZnO gap by raising the conduction-band potential and lowering the valence-band potential at a ratio of 0.68:0.32. Mg 2+ substitution is far more effective than Zn 2+ removal in raising the conduction-band potential and allows better reductants to be prepared from Zn 1-xMg xO nanocrystals than can be achieved via quantum confinement of ZnO nanocrystals. The increased conduction-band potentials of Zn 1-xMg xO nanocrystals compared to ZnO nanocrystals are confirmed by demonstration of spontaneous electron transfer from n-type Zn 1-xMg xO nanocrystals to smaller (more strongly quantum confined) ZnO nanocrystals. © 2012 American Chemical Society. Source


Lavine M.,University of Massachusetts Amherst
Ecology | Year: 2014

(1) Murtaugh and I agree on an important point: abandon accept/reject declarations. That alone will go a long way to improving statistical practice. (2) Don't confuse P values or DAIC with binary declarations. An argument against one is not necessarily an argument against the other. (3) Be careful interpreting a P value or DAIC as strength of evidence. That interpretation cannot be made formal and the connection between P, DAIC, and evidence must be recalibrated for each new problem. (4) Plot. Check models. Plot. Check assumptions. Plot. © 2014 by the Ecological Society of America. Source


Muthukumar M.,University of Massachusetts Amherst
Journal of Chemical Physics | Year: 2010

The translocation of macromolecules through a nanopore requires the impingement of the molecules at the pore followed by threading through the pore. While most of the discussion on the translocation phenomenon focused so far on the threading process, the phenomenology on the frequency of encounters between the polymer and the pore exhibits diverse features in terms of polymer length, solution conditions, driving force, and pore geometry. We derive a general theory for the capture rate of polyelectrolyte molecules and the probability of successful translocation through a nanopore, under an externally imposed electric field. By considering the roles of entropic barrier at the pore entrance and drift of the polyelectrolyte under the electric field, we delineate two regimes: (a) entropic barrier regime and (b) drift regime. In the first regime dominated by the entropic barrier for the polyelectrolyte, the capture rate is an increasing nonlinear function in the electric field and chain length. In the drift regime, where the electric field dwarfs the role of entropic barriers, the capture rate is independent of chain length and linear in electric field. An analytical formula is derived for the crossover behavior between these regimes, and the general results are consistent with various experimentally observed trends. © 2010 American Institute of Physics. Source


Kurose J.,University of Massachusetts Amherst
Computer Networks | Year: 2014

Today's information-centric networks (ICNs) represent a 100-year evolution of communication networks from circuit-switched networks to packet-switched networks to ICNs, sharing common features with both of these earlier network architectures, but having many unique characteristics of its own. We describe and survey ongoing research and identify challenges in the modeling, design and analysis of information-centric networks and protocols. We discuss performance modeling frameworks and challenges for ICNs, with a particular focus on content flowing through a network of caches, drawing analogies and distinctions from past research in both circuit-switched and packet-switched networks. We also survey the challenges and recent research results associated with finding content in a network of caches and managing the content in those caches. The challenges posed by mobility (of both the end users accessing content as well as content itself) are also discussed. © 2014 Elsevier B.V. All rights reserved. Source


Sheng Y.,University of California at Los Angeles | Abreu I.A.,New University of Lisbon | Abreu I.A.,Institute Biologia Experimental e Tecnologica | Cabelli D.E.,Brookhaven National Laboratory | And 5 more authors.
Chemical Reviews | Year: 2014

A scientific review presents information about superoxide dismutases and superoxide reductases. The review reveals that the superoxide reductase (SOR) and three very different types of superoxide dismutase (SOD) enzymes are redox-active metalloenzymes that have evolved entirely independently from one another for the purpose of lowering superoxide concentrations. SODs catalyze the disproportionation of superoxide to give O2 and H2O 2, a reaction requiring one proton per superoxide reacted without external reductant. All of the SOR enzymes contain only iron, while the three types of SODs are the nickel-containing SODs (NiSOD), the iron- or manganese-containing SODs (FeSOD and MnSOD), and the copper- and zinc-containing SODs (CuZnSOD). Source


Zilberberg M.D.,EviMed Research Group | Zilberberg M.D.,University of Massachusetts Amherst | Shorr A.F.,Washington Hospital Center
Infection Control and Hospital Epidemiology | Year: 2013

Objective. Urinary tract ifections (UTIs) are common among hospitalized patients. Selection of an appropriate antibiotic for this infection requires knowledge of both its general microbiology and the epidemiology of drug-resistant organisms. We sought to determine secular trends in UTI hospitalizations that involve gram-negative (GN) multidrug-resistant Pseudomonas aeruginosa (MDR-PA), extendedspectrum β-lactamase (ESBL)-producing Escherichia coli (EC) and Klebsiella pneumoniae (KP), and carbapenem-resistant Enterobacteriaceae (CRE). design. Survey. patients. Patients with UTI in US hospitals between 2000 and 2009. methods. We first derived the total number of UTI hospitalizations in the United States from the Healthcare Cost and Utilization Project Nationwide Inpatient Sample database years 2000-2009. Based on a literature review, we then determined what proportion of all UTIs arise due to each of the organisms of interest, irrespective of resistance pattern. Finally, we assessed the prevalence of resistance within each pathogen based on the Eurofins Surveillance Network database 2000-2009. Susceptibility patterns served as phenotypic surrogates for resistance. results. Between 2000 and 2009, the frequency of UTI hospitalizations increased by approximately 50%, from 53 to 77 cases per 1,000 hospitalizations. Infections due to all GN bacteria followed a similar trajectory, whereas those caused by resistant GN pathogens increased by approximately 50% (MDR-PA) to approximately 300% (ESBL). CRE emerged and reached 0.5 cases per 1,000 hospitalizations in this 10-year period. conclusions. The epidemiology and microbiology of GN UTI hospitalizations has shifted over the past decade. The proportion of all hospitalizations involving this infection has climbed. Resistant GN bacteria are becoming more prevalent and are implicated in an increasing proportion of UTIs among hospitalized patients. © 2013 by The Society for Healthcare Epidemiology of America. All rights reserved. Source


Weinberg M.D.,University of Massachusetts Amherst
Monthly Notices of the Royal Astronomical Society | Year: 2013

This paper introduces the Bayesian Inference Engine (BIE), a general parallel, optimized software package for parameter inference and model selection. This package is motivated by the analysis needs of modern astronomical surveys and the need to organize and reuse expensive derived data. The BIE is the first platform for computational statistics designed explicitly to enable Bayesian update and model comparison for astronomical problems. Bayesian update is based on the representation of high-dimensional posterior distributions using metric-ball-tree based kernel density estimation. Among its algorithmic offerings, the BIE emphasizes hybrid tempered Markov chain Monte Carlo schemes that robustly sample multimodal posterior distributions in high-dimensional parameter spaces. Moreover, the BIE implements a full persistence or serialization system that stores the full byte-level image of the running inference and previously characterized posterior distributions for later use. Two new algorithms to compute the marginal likelihood from the posterior distribution, developed for and implemented in the BIE, enable model comparison for complex models and data sets. Finally, the BIE was designed to be a collaborative platform for applying Bayesian methodology to astronomy. It includes an extensible object-oriented and easily extended framework that implements every aspect of the Bayesian inference. By providing a variety of statistical algorithms for all phases of the inference problem, a scientist may explore a variety of approaches with a single model and data implementation. Additional technical details and download details are available from http://www.astro.umass.edu/bie. The BIE is distributed under the GNU General Public License. ©2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. Source


Tremblay K.D.,University of Massachusetts Amherst
Progress in Molecular Biology and Translational Science | Year: 2010

The mammalian definitive endoderm arises as a simple epithelial sheet. This sheet of cells will eventually produce the innermost tube that comprises the entire digestive tract from the esophagus to the colon as well as the epithelial component of the digestive and respiratory organs including the thymus, thyroid, lung, liver, gallbladder, and pancreas. Thus a wide array of tissue types are derived from the early endodermal sheet, and understanding the morphological and molecular mechanisms used to produce this tissue is integral to understanding the development of all these organs. The goal of this chapter is to summarize what is known about the morphological and molecular mechanisms used to produce this embryonic germ layer. Although this chapter mainly focuses on the mechanisms used to generate the murine endoderm, supportive or suggestive data from other species, including chick, frog (Xenopus laevis), and the Zebrafish (Danio rerio) are also examined. © 2010 Elsevier Inc. Source


Maroney M.J.,University of Massachusetts Amherst | Ciurli S.,University of Bologna
Chemical Reviews | Year: 2014

The knowledge of the biochemistries, structures, and reaction mechanisms of enzymes whose active sites require nickel, and utilize it in a nonredox role, are reviewed. The selection of nickel as a catalytic center for biological reactions is related to its flexible coordination geometry, which makes this metal a very versatile element for biological applications. The biological roles of nickel enzymes are conveniently divided into redox and nonredox roles. S-donor ligands are strongly associated with Ni redox enzymes, which include a novel superoxide dismutase, and several other enzymes including hydrogenase and COdehydrogenase/acetyl coenzyme. An alternative reaction mechanism has been proposed that features different roles for the two Ni(II) ions, with Ni1 binding and activating urea, and Ni2 binding and activating the nucleophilic water by turning it into a hydroxide ion. Thus, the proposed Fe-ARD mechanism relies on transient redox chemistry, while Ni(II) is a simple Lewis acid. Source


Donoghue J.F.,University of Massachusetts Amherst
AIP Conference Proceedings | Year: 2012

This is a pedagogical introduction to the treatment of quantum general relativity as an effective field theory. It starts with an overview of the methods of effective field theory and includes an explicit example. Quantum general relativity matches this framework and I discuss gravitational examples as well as the limits of the effective field theory. I also discuss the insights from effective field theory on the gravitational effects on running couplings in the perturbative regime. © 2012 American Institute of Physics. Source


Calabrese E.J.,University of Massachusetts Amherst
Archives of Toxicology | Year: 2011

In his Nobel Prize Lecture of December 12, 1946, Hermann J. Muller argued that the dose-response for radiation-induced germ cell mutations was linear and that there was "no escape from the conclusion that there is no threshold". However, assessment of correspondence between Muller and Curt Stern 1 month prior to his Nobel Prize Lecture reveals that Muller knew the results and implications of a recently completed study at the University of Rochester under the direction of Stern, which directly contradicted his Nobel Prize Lecture. This finding is of historical importance since Muller's Nobel Lecture gained considerable international attention and is a turning point in the acceptance of the linearity model in risk assessment for germ cell mutations and carcinogens. © 2011 Springer-Verlag. Source


Chakrabarti A.,Cornell University | Chen A.W.,University of Massachusetts Amherst | Varner J.D.,Cornell University
Biotechnology and Bioengineering | Year: 2011

Proteins requiring post-translational modifications such as N-linked glycosylation are processed in the endoplasmic reticulum (ER). A diverse array of cellular stresses can lead to dysfunction of the ER and ultimately to an imbalance between protein-folding capacity and protein-folding load. Cells monitor protein folding by an inbuilt quality control system involving both the ER and the Golgi apparatus. Unfolded or misfolded proteins are tagged for degradation via ER-associated degradation (ERAD) or sent back through the folding cycle. Continued accumulation of incorrectly folded proteins can also trigger the unfolded protein response (UPR). In mammalian cells, UPR is a complex signaling program mediated by three ER transmembrane receptors: activating transcription factor 6 (ATF6), inositol requiring kinase 1 (IRE1) and double-stranded RNA-activated protein kinase (PKR)-like endoplasmic reticulum kinase (PERK). UPR performs three functions, adaptation, alarm, and apoptosis. During adaptation, the UPR tries to reestablish folding homeostasis by inducing the expression of chaperones that enhance protein folding. Simultaneously, global translation is attenuated to reduce the ER folding load while the degradation rate of unfolded proteins is increased. If these steps fail, the UPR induces a cellular alarm and mitochondrial mediated apoptosis program. UPR malfunctions have been associated with a wide range of disease states including tumor progression, diabetes, as well as immune and inflammatory disorders. This review describes recent advances in understanding the molecular structure of UPR in mammalian cells, its functional role in cellular stress, and its pathophysiology. © 2011 Wiley Periodicals, Inc. Source


Sievert L.L.,University of Massachusetts Amherst
Menopause | Year: 2014

Objective: This work aims to consider how the discipline of anthropology contributes to the study of menopause through evolutionary, developmental, and comparative perspectives.Methods: This study was a review of skeletal and ethnographic evidence for menopause and postreproductive life in humans' distant past, hypotheses for the evolution of menopause and long postreproductive life, variation in age at menopause with focus on childhood environments, and the study of variation in symptomexperience across populations.Results: Longevity, rather than capacity for menopause, sets humans apart from other primates. Skeletal evidence demonstrates that some Neanderthals and archaic Homo sapiens lived to the age at menopause and that at least one third of women in traditional foraging populations live beyond menopause. The evolutionary reasons for why women experience a long postreproductive life continue to be debated. A developmental perspective suggests that early childhood may be a critical time for the environment to irreversibly influence the number of oocytes or rate of follicular atresia and, ultimately, age at menopause. A comparative perspective examines symptom experience at midlife through participant observation, qualitative interviews, and quantitative instruments to gain a holistic understanding of the meaning, experience, and sociocultural context of menopause.Conclusions: An evolutionary perspective suggests that menopause is not a recent phenomenon among humans. A developmental perspective focuses on the influence of early childhood on ovarian function. A comparative perspective expands clinical norms and provides knowledge about the range of human variations. © 2014 The North American Menopause Society. Source


Burand J.P.,University of Massachusetts Amherst | Hunter W.B.,U.S. Department of Agriculture
Journal of Invertebrate Pathology | Year: 2013

RNA interference is a post- transcriptional, gene regulation mechanism found in virtually all plants and animals including insects. The demonstration of RNAi in insects and its successful use as a tool in the study of functional genomics opened the door to the development of a variety of novel, environmentally sound approaches for insect pest management. Here the current understanding of the biogenesis of the two RNAi classes in insects is reviewed. These are microRNAs (miRNAs) and short interfering RNAs (siRNAs). Several other key approaches in RNAi -based for insect control, as well as for the prevention of diseases in insects are also reviewed. The problems and prospects for the future use of RNAi in insects are presented. © 2013 International Atomic Energy Agency. Source


Huntsinger J.R.,Loyola University Chicago | Isbell L.M.,University of Massachusetts Amherst | Clore G.L.,University of Virginia
Psychological Review | Year: 2014

Despite decades of research demonstrating a dedicated link between positive and negative affect and specific cognitive processes, not all research is consistent with this view. We present a new overarching theoretical account as an alternative-one that can simultaneously account for prior findings, generate new predictions, and encompass a wide range of phenomena. According to our proposed affect-ascognitive- feedback account, affective reactions confer value on accessible information processing strategies (e.g., global vs. local processing) and other responses, goals, concepts, and thoughts that happen to be accessible at the time. This view underscores that the relationship between affect and cognition is not fixed but, instead, is highly malleable. That is, the relationship between affect and cognitive processing can be altered, and often reversed, by varying the mental context in which it is experienced. We present evidence that supports this account, along with implications for specific affective states and other subjective experiences. © 2014 American Psychological Association. Source


Jenkins E.B.,Princeton University | Tripp T.M.,University of Massachusetts Amherst
Astrophysical Journal | Year: 2011

We analyzed absorption features arising from interstellar neutral carbon that appeared in the UV spectra of 89 stars recorded in the highest resolution echelle modes of the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope so that we could determine the relative populations of collisionally excited fine-structure levels in the atom's electronic ground state. From this information, in combination with molecular hydrogen rotation temperatures, we derive the distribution of thermal pressures in the diffuse, cold neutral medium (CNM). We find a lognormal pressure distribution (weighted by mass) with a mean in log (p/k) equal to 3.58 and an rms dispersion of at least 0.175dex that plausibly arises from turbulence with a characteristic Mach number in the range 1 < M < 4. The extreme tails in the distribution are, however, above the lognormal function. Overall, pressures are well correlated with local starlight intensities and extreme kinematics, and they show some anticorrelation with kinetic temperatures. A subsample restricted to low ambient UV intensities reveals a mode in the distribution of log (p/k) that is nearly the same as the complete sample, but with a strong negative skewness created by a near absence of a tail at high pressures. Approximately 23% of this gas is at a pressure that is below that which is allowed for a static CNM. Accompanying nearly all of the gas is a small fraction (∼ 0.05%) that has an extraordinarily large pressure, log (p/k) > 5.5, and this condition is more prevalent at high velocities or for regions with enhanced starlight densities. This survey suggests that the dispersion of thermal pressures in the CNM is predominantly governed by microscopic turbulence driven by star-forming regions, with some additional effects from macroscopic events (e.g., supernova explosions), and these measurements provide constraints for future studies of the broader impact of turbulence on the ISM and star formation. © 2011. The American Astronomical Society. All rights reserved. Source


McGregor A.,University of Massachusetts Amherst
SIGMOD Record | Year: 2014

Over the last decade, there has been considerable interest in designing algorithms for processing massive graphs in the data stream model. The original motivation was two-fold: a) in many applications, the dynamic graphs that arise are too large to be stored in the main memory of a single machine and b) considering graph problems yields new insights into the complexity of stream computation. However, the techniques developed in this area are now finding applications in other areas including data structures for dynamic graphs, approximation algorithms, and distributed and parallel computation. We survey the state-of-the-art results; identify general techniques; and highlight some simple algorithms that illustrate basic ideas. Source


Hess T.J.,University of Massachusetts Amherst | McNab A.L.,Niagara University | Basoglu K.A.,University of Delaware
MIS Quarterly: Management Information Systems | Year: 2014

A reliability generalization study (a meta-analysis of reliability coefficients) was conducted on three widely studied information systems constructs from the technology acceptance model (TAM): perceived ease of use, perceived usefulness, and behavioral intentions. This form of meta-analysis summarizes the reliability coefficients of the scores on a specified scale across studies and identifies the study characteristics that influence the reliability of these scores. Reliability is a critical issue in conducting empirical research as the reliability of the scores on well-established scales can vary with study characteristics, attenuating effect sizes. In conducting this study, an extensive literature search was conducted, with 380 articles reviewed and coded to perform reliability generalization. Study characteristics, including technology, sample, and measurement characteristics, for these articles were recorded along with effect size data for the relationships among these variables. After controlling for number of items, sample size, and sampling error, differences in reliability coefficients were found with several study characteristics for the three technology acceptance constructs. The reliability coefficients of PEOU and PU were lower in hedonic contexts than in utilitarian contexts, and were higher when the originally validated scales were used as compared to when other items were substituted. Only 27 percent of the studies that provided the measurement items used the original PEOU items, while 39 percent used the original PU items. Scales that were administered in English had higher reliability coefficients for PU and BI, with a marginal effect for PEOU. Reliability differences were also found for other study characteristics, including reliability type, subject experience, and gender composition. While average reliability coefficients were high, the results show that, on average, relationships among these constructs are attenuated by 12 percent with maximum attenuation in the range of 35 to 43 percent. Implications for technology acceptance research are discussed and suggestions for addressing variation in reliability coefficients across studies are provided. Source


The addition of multifunctional additives comprised of single- or double-ring aromatic cores decorated at their periphery with multiple hydrogen-bond-donating groups such as carboxylic acid and phenol is shown to induce microphase segregation of otherwise disordered Pluronic BCP (poly(ethylene oxide-propylene oxide-ethylene oxide)) surfactant melts, resulting in the formation of well-ordered supramolecular assemblies with domain spacings ranging between 12.5 and 14.5 nm at additive loadings up to 40%. As the concentration of additives is increased, the general tendency is that the disordered system evolves into an ordered morphology and then undergoes an order-order transition before transitioning into a disordered phase, in one case. The scaling of interplanar spacing reveals that the additives are selectively incorporated in the poly(ethylene oxide) phase. Differential scanning calorimetry indicated that progressive increases in the loading of additives causes a decrease in the melting temperature and melting enthalpy of poly(ethylene oxide) crystallites. This behavior is consistent with good dispersion and strong interaction of the additives with the poly(ethylene oxide) phase. The principles invoked in this additive driven assembly process can be generally applied to the design of ordered functional BCP-nanoparticle hybrid materials while the specific materials described here could be of interest as etch masks. © 2010 American Chemical Society.. Source


Morse S.A.,University of Massachusetts Amherst
Journal of Petrology | Year: 2012

The range in An content of plagioclase in grain mounts of igneous cumulates provides a measure of diversity that is uniquely preserved in plagioclase because of its well-known refractory nature. To a first approximation such data provide, when calibrated, an estimate of the residual porosity or fraction of trapped liquid, in each specimen. The ensemble of specimens then provides a model for the stratigraphic variation of residual porosity. The raw data, however, include pre-cumulus zoning that can be isolated from in situ zoning by textural analysis in thin section. The baseline of residual porosity determinations was earlier determined for the Lower Zone of the Kiglapait intrusion from the content of excluded components in the solid rock compared with their content in the melt as calculated by summation and Rayleigh fractionation. The baseline equation was then used to calibrate the residual porosity obtained from the An range in grain mounts. This calibration is now extended to the remainder of the intrusion. The An range and the calculated residual porosity decrease to zero at 99% solidified (PCS) and then rise to the end of crystallization. The data suggest initial porosities smaller than 0·35. Allowing for pre-cumulus zoning, the data suggest a dominance of adcumulates in the intrusion and these impermeable barriers occupy 75% of the rocks in the Lower Zone. They occur at intervals of 1 to rarely 15 m and thereby restrict the likelihood of compaction over thick mushy zones. Variations in the Fo range of olivine are also observed in grain mounts and they follow those in plagioclase. However, they are in part due to subsolidus equilibration with Fe-Ti oxides and augite. The new calibration is successfully applied to the Skaergaard intrusion to supplement the published results from excluded components, with some interesting contradictions. © The Author 2012. Published by Oxford University Press. All rights reserved. Source


Vogl O.,University of Massachusetts Amherst
Journal of Polymer Science, Part A: Polymer Chemistry | Year: 2011

The creation of chirality on Earth and the development of chiral life have been discussed in this highlight. Convincing evidence for the introduction of chirality on Earth is still fragmentary. We believe that by a combination of chiral crystallization and formation of helical polymers with preferred chiral conformational structure is the key to this question. This concept of macromolecular asymmetry has inspired ideas and resulted in possible rules for how chiral life as we know it, could have been introduced. These investigations needed the understanding of the requirements for chiral crystallization, for the stereochemistry of the initial formation of helical polymers, the measurements of optical activity of solids and their coordination with the fundamentals of chirality. Spacial modeling of the "oligo-crystallization" of sodium chlorate led to the conception of "isotactic" linear crystallization, which involves helical propagation. It seems to require unequal sizes of the cations and anions, which, by branching propagation leads to three-dimensional chiral crystal formation. Linear "isotactic" propagation of crystallization seems to be equivalent to stereo and conformational specific polymerization. One and a half turns of the helix seems to be required for stereo- and conformational specificity, that is, between the pentamer and hexamer in chloral polymerization (11/3 or nearly 4/1 helix) and between trimer and tetramer for the sodium chlorate crystal (2/1 helix). © 2011 Wiley Periodicals, Inc. Source


Sharp D.J.,Yeshiva University | Ross J.L.,University of Massachusetts Amherst
Journal of Cell Science | Year: 2012

ATP-dependent severing of microtubules was first reported in Xenopus laevis egg extracts in 1991. Two years later this observation led to the purification of the first known microtubule-severing enzyme, katanin. Katanin homologs have now been identified throughout the animal kingdom and in plants. Moreover, members of two closely related enzyme subfamilies, spastin and fidgetin, have been found to sever microtubules and might act alongside katanins in some contexts (Roll-Mecak and McNally, 2010; Yu et al., 2008; Zhang et al., 2007). Over the past few years, it has become clear that microtubule-severing enzymes contribute to a wide range of cellular activities including mitosis and meiosis, morphogenesis, cilia biogenesis and disassembly, and migration. Thus, this group of enzymes is revealing itself to be among the most important of the microtubule regulators. This Commentary focuses on our growing understanding of how microtubule-severing enzymes contribute to the organization and dynamics of diverse microtubule arrays, as well as the structural and biophysical characteristics that afford them the unique capacity to catalyze the removal of tubulin from the interior microtubule lattice. Our goal is to provide a broader perspective, focusing on a limited number of particularly informative, representative and/or timely findings. © 2012. Source


Kwon D.-H.,University of Massachusetts Amherst
IEEE Antennas and Wireless Propagation Letters | Year: 2012

Based on quasi-conformal coordinate transformation, lens designs for conformal array antenna applications are presented. Potentially over a broad bandwidth for the two-dimensional TE polarization, a physically linear array can be transformed into a virtual curved array, or vice versa, using a lens having only nonmagnetic medium parameters. Lens designs for transforming between linear and cylindrical arrays in conformal conducting ground planes as well as their predicted scanning performances are shown. Such lenses can be designed and applied to existing array antennas to enable new scanning capabilities. © 2012 IEEE. Source


Goldner L.S.,University of Massachusetts Amherst
Methods in enzymology | Year: 2010

We describe a method for molecular confinement and single-fluorophore sensitive measurement in aqueous nanodroplets in oil. The sequestration of individual molecules in droplets has become a useful tool in genomics and molecular evolution. Similarly, the use of single fluorophores, or pairs of fluorophores, to study biomolecular interactions and structural dynamics is now common. Most often these single-fluorophore sensitive measurements are performed on molecules that are surface attached. Confinement via surface attachment permits molecules to be located and studied for a prolonged period of time. For molecules that denature on surfaces, for interactions that are transient or out-of-equilibrium, or to observe the dynamic equilibrium of freely diffusing reagents, surface attachment may not be an option. In these cases, droplet confinement presents an alternative method for molecular confinement. Here, we describe this method as used in single-fluorophore sensitive measurement and discuss its advantages, limitations, and future prospects. Copyright 2010 Elsevier Inc. All rights reserved. Source


Gao S.,University of Massachusetts Amherst
IEEE Transactions on Intelligent Transportation Systems | Year: 2012

This paper establishes a general framework to study the impacts of real-time information on the users' routing decisions and the system cost in a stochastic time-dependent traffic network under a generalized equilibrium condition. Users are assumed to make strategic routing decisions, and the rule that maps a user's current state, including node, time, and information, to a decision on the next node to take, is defined as a routing policy. This definition allows for a wide variety of information accessibility situations, thus excluding the usually simplified assumptions, such as either no information or full information. A user's choice set contains routing policies rather than simple paths. A fixed-point problem formulation of the user equilibrium is given, and a method of successive average heuristic is designed. Computational tests are carried out in a hypothetical network, where random incidents are the source of stochasticity. System costs derived from three models with different information accessibility situations are compared. The strategic route choices lead to shorter expected travel times at equilibrium. Smaller travel time variances are obtained as a byproduct. The value of real-time information is an increasing function of the incident probability. However, it is not a monotonic function of the market penetration of information, which suggests that in designing a traveler information system or route guidance system, the information penetration needs to be chosen carefully to maximize benefits. © 2012 IEEE. Source


Hohlfeld E.,University of Massachusetts Amherst
Physical Review Letters | Year: 2013

Cavitation and sulcification of soft elastomers are two examples of thresholdless, nonlinear instabilities that evade detection by linearization. I show that the onset of such instabilities can be understood as a kind of phase coexistence between multiple scale-invariant states, and I constructively enumerate the possible scale-invariant states of incompressible rubber in two dimensions. Whereas true phases (like the affine deformations of rubber) are homogeneous, the alternatives are inhomogeneous. In terms of the thermodynamics of solids, both classes of states must generally be given equal consideration. © 2013 American Physical Society. Source


Boutt D.F.,University of Massachusetts Amherst
Ground Water | Year: 2010

Short-term changes in the hydraulic head of surface water bodies are known to influence the shallow response of hydraulically connected groundwaters. Associated with these fluctuations is the physical increase in stream water creating a mechanical load on the ground surface. This load is supported by the geologic materials (sediment or rock) and the pore fluid contained within the pores. Changes in this surface load have a direct effect on the total stress of the aquifer causing either a change in effective stress or fluid pressure. This response, predicted by the framework of linear poroelasticity, is a well-understood phenomenon in geologic materials. Currently, field measurements of the hydraulic response (i.e., fluid pressure) of aquifer materials are undergoing poroelastic loading due to dam releases in the Deerfield River Watershed in Massachusetts. An increase in stream stage from upstream dam releases causes an instantaneous pore fluid pressure increase at multiple depths and locations in the aquifer. This increase lasts anywhere from 15 to 40 minutes depending on the magnitude of the rise in the stream stage. Pore-pressure changes are well correlated to stream stage fluctuations for all of the recorded events. Poroelastic models created using basin stratigraphy and hydraulic properties of the aquifer response match the field observations well. Model results suggest that the overall stratigraphy is important in controlling the magnitude and duration of the poroelastic response. An improved understanding of responses such as these can be used to constrain uncertainties in model calibration and simulations of the contaminant migration in low permeability fine-grained (compressive) materials. Copyright © 2010 The Author(s). Journal compilation © 2010 National Ground Water Association. Source


McClements D.J.,University of Massachusetts Amherst
Advances in Nutrition | Year: 2015

Fat plays multiple roles in determining the desirable physicochemical properties, sensory attributes, nutritional profile, and biologic response of food products. Overconsumption of fats is linked to chronic diseases, such as obesity, coronary heart disease, diabetes, and cancer. There is therefore a need to develop reduced-fat products with physicochemical properties and sensory profiles that match those of their full-fat counterparts. In addition, foods may be redesigned to increase the feelings of satiety and satiation, and thereby reduce overall food intake. The successful design of these types of functional foods requires a good understanding of the numerous roles that fat plays in determining food attributes and the development of effective strategies to replace these attributes. This article provides an overview of the current understanding of the influence of fat on the physicochemical and physiologic attributes of emulsion-based food products and highlights approaches to create high-quality foods with reduced-fat contents. Source


Calabrese E.J.,University of Massachusetts Amherst
Human and Experimental Toxicology | Year: 2013

The goal of this article was to assess the historical role of radiotherapy in the treatment of selected inflammatory diseases. The specific research involved a literature-based assessment of the use of x-rays during the first half of the 20th century for the treatment of furuncles and carbuncles, the potentially serious staphylococcus infections. X-Rays were reported to be effective as a treatment at relatively low dose, about 10-20% of the skin erythema dose, which often quickly and profoundly reduce pain and accelerate the resolution/healing of the furuncles and carbuncles. These findings were based on considerable clinical experience that was generally reported in the form of case studies. The mechanism of x-ray-induced reduction of inflammation and acceleration of healing was suggested to result from a combination of immune alterations that enhanced phagocytosis as well as via an anti-localization effect on the pathogenic organism that facilitates their destruction. © The Author(s) 2013. Source


Dynamic Digital Maps (DDMs) are computer programs that manage the display and distribution of high-quality color maps, digital images, movies, analytical data, and explanatory text, including field guides. They do this in a cross-platform format that opens associated files of maps, images, and movies either from a local device (e.g., a hard drive) or from a web source (server). DDMs are intuitive to use, can be easily and quickly searched for sample and image sites and analytical data, and require no additional software such as web browsers or readers to operate. DDMs fill a niche between the extremes in the digital mapping world that range from a simple digital copy of a paper map to the highly linked geographic information system (GIS) product. A DDM enables one to create an integrated study that confines its focus on a specific map, unlike other interfaces. They offer an ideal way to present, for example, premeeting or postmeeting field trips, so they can be pre-run or revisited, enriching the experience. All DDM maps and images can be saved to disk for printing, and data saved to tab-delimited files. DDMs are made using the open-source DDM-Template, written in the cross-platform programming environment Runtime Revolution, as assisted by videos, tutorials, and the DDM-Cookbook. The DDM of the Springerville volcanic field, the example used here to demonstrate these capabilities, was made from this template. The template is highly extensible, and ongoing modifications and updates are available, as are more than 20 other examples of DDMs. © 2010 Geological Society of America. Source


Landgraf D.,Harvard University | Okumus B.,Harvard University | Chien P.,Massachusetts Institute of Technology | Chien P.,University of Massachusetts Amherst | And 2 more authors.
Nature Methods | Year: 2012

We introduce a nonintrusive method exploiting single-cell variability after cell division to validate protein localization. We found that Clp proteases, widely reported to form biologically relevant foci, were uniformly distributed in Escherichia coli cells, and that many commonly used fluorescent proteins caused severe mislocalization when fused to homo-oligomers. Retagging five other reportedly foci-forming proteins with the most monomeric fluorescent protein tested suggests that the foci were caused by the fluorescent tags. © 2012 Nature America, Inc. All rights reserved. Source


Frinken V.,University of Bern | Fischer A.,University of Bern | Manmatha R.,University of Massachusetts Amherst | Bunke H.,University of Bern
IEEE Transactions on Pattern Analysis and Machine Intelligence | Year: 2012

Keyword spotting refers to the process of retrieving all instances of a given keyword from a document. In the present paper, a novel keyword spotting method for handwritten documents is described. It is derived from a neural network-based system for unconstrained handwriting recognition. As such it performs template-free spotting, i.e., it is not necessary for a keyword to appear in the training set. The keyword spotting is done using a modification of the CTC Token Passing algorithm in conjunction with a recurrent neural network. We demonstrate that the proposed systems outperform not only a classical dynamic time warping-based approach but also a modern keyword spotting system, based on hidden Markov models. Furthermore, we analyze the performance of the underlying neural networks when using them in a recognition task followed by keyword spotting on the produced transcription. We point out the advantages of keyword spotting when compared to classic text line recognition. © 2012 IEEE. Source


Lee S.J.,Massey University | McClements D.J.,University of Massachusetts Amherst
Food Hydrocolloids | Year: 2010

Oil-in-water nanoemulsions containing small lipid droplets (d < 100 nm) are finding increasing applications within the food industry as delivery systems in transparent foods and beverages, and to increase the bioavailability of lipophilic active agents. In this study, we show that nanoemulsions can be fabricated from food-grade ingredients (corn oil, whey protein, and water) using simple processing operations (homogenization, dilution and solvent evaporation). Nanoemulsions were formed by homogenizing 10 wt% organic phase (corn oil and ethyl acetate) with 90 wt% aqueous phase (water and whey protein isolate). The mean particle diameter of the emulsions decreased with increasing ethyl acetate concentration in the organic phase, which was attributed to its ability to alter the size of the droplets produced during homogenization, as well as its ability to be removed from the droplets by dissolution and/or evaporation after homogenization. The particle size also decreased with increasing emulsifier concentration. These nanoemulsions may be useful as delivery systems in the food, pharmaceutical and cosmetics industries. © 2010 Elsevier Ltd. Source


Pietromonaco P.R.,University of Massachusetts Amherst | Uchino B.,University of Utah | Schetter C.D.,University of California at Los Angeles
Health Psychology | Year: 2013

Objectives: Health psychology has contributed significantly to understanding the link between psychological factors and health and well-being, but it has not often incorporated advances in relationship science into hypothesis generation and study design. We present one example of a theoretical model, following from a major relationship theory (attachment theory) that integrates relationship constructs and processes with biopsychosocial processes and health outcomes. Method: We briefly describe attachment theory and present a general framework linking it to dyadic relationship processes (relationship behaviors, mediators, and outcomes) and health processes (physiology, affective states, health behavior, and health outcomes). We discuss the utility of the model for research in several health domains (e.g., self regulation of health behavior, pain, chronic disease) and its implications for interventions and future research. Results: This framework revealed important gaps in knowledge about relationships and health. Future work in this area will benefit from taking into account individual differences in attachment, adopting a more explicit dyadic approach, examining more integrated models that test for mediating processes, and incorporating a broader range of relationship constructs that have implications for health. Conclusions: A theoretical framework for studying health that is based in relationship science can accelerate progress by generating new research directions designed to pinpoint the mechanisms through which close relationships promote or undermine health. Furthermore, this knowledge can be applied to develop more effective interventions to help individuals and their relationship partners with healthrelated challenges. © 2013 American Psychological Association. Source


Shi S.,University of Massachusetts Amherst
Telematics and Informatics | Year: 2013

Based on a nationwide survey of more than 500 CSOs in China conducted in 2009, the research presented herein provides the first set of data and the first quantitative analysis regarding the use of Web2.0 technologies among Chinese CSOs. First, it attempts to answer the basic but crucial questions: Whether, on the whole, China's CSOs use Web2.0 style technologies, and how widely different Web2.0 style technologies have been adopted among China's CSOs. Second, it attempts to answer whether there is a regional difference (East China/Central China/West China) in the adoption of Web2.0 technologies; whether there is a difference in Web2.0 technologies adoption by financial resource (of CSOs); if yes, which group of CSOs are disadvantaged. This research found that most of the chosen Web2.0 style technologies have been widely adopted by CSOs. The use of Web2.0 style technologies and social media is likely to become a widespread phenomenon among CSOs in China. We found CSOs with medium financial support are more likely to use Web2.0, whereas CSOs with high financial support are left behind in the use of some Web2.0 technologies. More importantly, we found there is a regional inequality in the adoption of Web2.0 style technologies. CSOs in western China are left behind in the adoption of Web2.0. And CSOs in eastern China are more likely to use blog and Forum/BBS; CSOs in central China are more likely to upload video materials. © 2012 Elsevier Ltd. All rights reserved. Source


Lahti P.M.,University of Massachusetts Amherst
Advances in Physical Organic Chemistry | Year: 2011

This chapter gives an introduction to the basic concepts of magnetism in organic paramagnetic soft matter materials. Key concepts are emphasized using example case studies. Detailed analysis covers radicals functionalized with phenols and with benzimidazole functionalities, which induce various degrees of crystal self-assembly, depending on specific structures. A review with over 200 references and notes. © 2011 Elsevier Inc. Source


Achilleos V.,National and Kapodistrian University of Athens | Frantzeskakis D.J.,National and Kapodistrian University of Athens | Kevrekidis P.G.,University of Massachusetts Amherst | Pelinovsky D.E.,McMaster University
Physical Review Letters | Year: 2013

We study matter-wave bright solitons in spin-orbit coupled Bose-Einstein condensates with attractive interactions. We use a multiscale expansion method to identify solution families for chemical potentials in the semi-infinite gap of the linear energy spectrum. Depending on the linear and spin-orbit coupling strengths, the solitons may present either a sech2-shaped or a modulated density profile reminiscent of the stripe phase of spin-orbit coupled repulsive Bose-Einstein condensates. Our numerical results are in excellent agreement with our analytical findings and demonstrate the potential robustness of solitons for experimentally relevant conditions. © 2013 American Physical Society. Source


This paper extends several recent publications indicating that Hermann J. Muller: (1) Made deceptive statements during his Noble Prize Lecture on December 12, 1946, that were intended to promote the acceptance of the linear dose-response model for risk assessment for ionizing radiation and (2) that such actions of Muller were masked by a series of decisions by Muller's long-time colleague and esteemed radiation geneticist Curt Stern, affecting key publications in the mutation literature. Such actions further enhanced acceptance of the linearity dose-response model while preventing Muller's deceptions from being discovered. This paper provides documentation that Muller reinforced such practices within the scientific literature in the early 1950s, by supporting scientifically questionable actions of Stern. Detailed documentation is provided that demonstrates how these actions affected national and international risk assessment policy for ionizing radiation and chemical carcinogens via the recommendations of the National Academy of Sciences Biological Effects of Atomic Radiation committee in 1956, to adopt the linear dose-response model. © 2013 Springer-Verlag Berlin Heidelberg. Source


Recent speleothem records from the tropics of both hemispheres document a gradual decrease in the intensity of the monsoons in the Northern Hemisphere and increase in the Southern Hemisphere monsoons over the Holocene. These changes are a direct response of the monsoons to precession-driven insolation variability. With regard to atmospheric methane, this shift should result in a decrease in Northern Hemisphere tropical methane emissions and increase in Southern Hemisphere emissions. It is plausible that that overall tropical methane production experienced a minimum in the mid-Holocene because of decreased seasonality in rainfall at the margins of the tropics. Changes in tropical methane production alone might, therefore, explain many of the characteristics of Holocene methane concentrations and isotopic chemistry. © The Author(s) 2011. Source


Janaswamy R.,University of Massachusetts Amherst
IEEE Transactions on Antennas and Propagation | Year: 2011

By considering the 2D problem of electrical line sources radiating in the presence of perfectly conducting cylinders and decomposing the real power flow on a circumscribing observation circle separating the transmit nodes from the receive nodes, simple formulas are derived for the electromagnetic degrees of freedom in scattering environments for a network of nodes communicating with each other. The locations, magnitudes, and phases of the line sources are assumed to be independent and identically distributed (i.i.d.) random variables. Similarly, the locations of the scatterers in the region outside the observation circle are assumed to be i.i.d. random variables. The exact scattering problem is cast in the form of an integral equation, where the Fourier coefficients of the scatter current density are the unknowns. Based on the Born approximation that is valid for mild scatter densities and asymptotic analysis, a closed form expression is derived for the number of degrees of freedom in scattering environments. The benefit of observing near-fields in the determination of degrees of freedom is included in the numerical examples considered. If the power per source and/or the number of sources within the circumscribing circle are made to increase algebraically with the size of the circle, it is shown that scattering environments can offer much higher degrees of freedom than what are available in free-space. © 2011 IEEE. Source


Calabrese E.J.,University of Massachusetts Amherst | Calabrese V.,University of Catania
International Journal of Radiation Biology | Year: 2013

Purpose: The aim of this paper was to provide an integrative mechanistic appraisal to account for consistent observations of protective effects of ionizing radiation on the occurrence/ progression of arthritis in multiple animal models. Materials and methods: A critical analysis of the biomedical literature was undertaken to assess mechanisms by which low doses of ionizing radiation prevent and/or reduce the occurrence of experimental-induced arthritis in animal models. Results: Detailed mechanistic-related research indicates that low doses of ionizing radiation induce a highly integrated multiple pathway process that results in the formation of a generalized anti-inflammatory phenotype which can both prevent the occurrence of arthritic changes and/or reverse such effects. Conclusions: The manifestation of the anti-inflammatory features occurred within the context of highly consistent hormetic (i.e., biphasic dose) responses across studies, biological models and mechanisms. The reduction of multiple bioindicators of experimentally-induced arthritis by exposure to low doses of ionizing radiation was associated with the occurrence of a generalized anti-inflammatory phenotype. © 2013 Informa UK, Ltd. Source


Krause E.L.,University of Massachusetts Amherst
Medical Anthropology Quarterly | Year: 2012

Even in a country with super-low fertility rates, at least one-quarter of all babies are unplanned. The finding puzzles policymakers. This article uses Italy's "curious case" as a jumping-off point to expose assumptions about rationality. It offers a model to dismantle the "conceit" of rationality, drawing on Max Weber's classic critique and Emily Martin's contemporary appraisal. It asks: (1) How do assumptions about rationality related to sexuality and reproduction manifest? (2) How do qualitative data challenge rationalist assumptions? and (3) How are cultural logics expressed and what do they reveal about the "problem" of low fertility? Methodologically, the article offers an innovative approach, juxtaposing ethnographic data derived from the author's fieldwork with startling findings from Italian researchers' multicity project. The analysis exposes the rationality trope as a technique of governance in a context in which policymakers yearn for social cohesion and population politics intensify around birthing, immigration, and aging. © 2012 by the American Anthropological Association. Source


Schlinger B.A.,Brain Research Institute | Remage-Healey L.,University of Massachusetts Amherst
Journal of Neuroendocrinology | Year: 2012

The long-held dogma that the brain is a target of steroids produced by peripheral organs has delayed the widespread acceptance of the functional importance of neurosteroidogenesis. Comparative studies have been vital for establishing the key actions of gonadal and adrenal hormones on brain and behaviour. No doubt, studies across diverse phyla will continue to be crucial for revealing the true significance of neurosteroidogenesis to proper function of the vertebrate brain. Here, we review work carried out in our laboratory, as well as in others, highlighting advances to our understanding of brain steroid synthesis and action using songbirds as animal models. These studies show that steroidogenic transporters and enzymes are present in the songbird brain and that their expression and/or activities are subject to developmental, seasonal or short-term regulation. Our work in a songbird points to synaptic synthesis of neuroactive steroids and fast, perisynaptic membrane actions. Combined with evidence for rapid steroidal control of behaviour, these studies firmly establish a neuromodulatory role for avian neurosteroids. We hope this work will join with that of other species to embolden the acceptance of neurosteroidal signalling as a core property of vertebrate neurobiology. © 2011 Blackwell Publishing Ltd. Source


Lackner M.A.,University of Massachusetts Amherst
Wind Energy | Year: 2013

This paper investigates the loads on offshore floating wind turbines and a new control method that can be used to reduce these loads. In this variable power collective pitch control method, the rated generator speed, which is the set point that the collective pitch control attempts to drive the actual generator speed towards, is no longer a constant value but instead a variable that depends on the platform pitch velocity. At a basic physical level, this controller achieves the following: as the rotor of a floating turbine pitches upwind, the controller adjusts so as to extract more energy from the wind by increasing the rated generator speed and thus damps the motion; as the rotor pitches downwind, less energy is extracted because the controller reduces the rated generator speed and again damps the motion. This method is applied to the NREL 5 MW wind turbine model, in above-rated conditions where the platform motion is most problematic. The results indicate significant load reductions on key structural components, at the expense of minor increases in power and speed variability. The loads on the blades and tower are investigated more generally, and simple dynamic models are used to gain insight into the behavior of floating wind turbine systems. It is clear that for this particular design, aerodynamic methods for reducing platform motion and tower loads are likely inadequate to allow for a viable design, and so new designs or possibly new control degrees of freedom are needed. Copyright © 2012 John Wiley & Sons, Ltd. Source


Scherf K.S.,Pennsylvania State University | Scott L.S.,University of Massachusetts Amherst
Developmental Psychobiology | Year: 2012

The nature of the developmental trajectory of face recognition abilities from infancy through adulthood is multifaceted and currently not well understood. We argue that the understanding of this trajectory can be greatly informed by taking a more functionalist approach in which the influence of age-appropriate developmental tasks and goals are considered. To build this argument, we provide a focused review of developmental change across several important biases within face processing (species, race, age, and gender biases) from infancy through adulthood. We show that no existing theoretical framework can simultaneously and parsimoniously explain these very different trajectories and relative degrees of plasticity. We offer several examples of infant- and adolescent-specific developmental tasks that we predict have an essential influence on the content and description of information that individuals need to extract from faces at these very different developmental stages. Finally, we suggest that this approach may provide a unique opportunity to study the role of early experience in (i.e., age of acquisition effects) and the quality and range of experiences that are critical for shaping behaviors through the course of development, from infancy to adulthood. © 2012 Wiley Periodicals, Inc. Source


Woodcock C.L.,University of Massachusetts Amherst
Cold Spring Harbor perspectives in biology | Year: 2010

The primary role of the nucleus as an information storage, retrieval, and replication site requires the physical organization and compaction of meters of DNA. Although it has been clear for many years that nucleosomes constitute the first level of chromatin compaction, this contributes a relatively small fraction of the condensation needed to fit the typical genome into an interphase nucleus or set of metaphase chromosomes, indicating that there are additional "higher order" levels of chromatin condensation. Identifying these levels, their interrelationships, and the principles that govern their occurrence has been a challenging and much discussed problem. In this article, we focus on recent experimental advances and the emerging evidence indicating that structural plasticity and chromatin dynamics play dominant roles in genome organization. We also discuss novel approaches likely to yield important insights in the near future, and suggest research areas that merit further study. Source


Bittman E.L.,University of Massachusetts Amherst
Journal of Biological Rhythms | Year: 2014

The duper mutation in Syrian hamsters shortens the free-running period (DD) of locomotor activity by approximately 1 h when expressed on the wild-type background and by 2 h on the tau mutant background ("super duper"). In either case, duper markedly amplifies the phase response curve (PRC) of the light pulse. This work examined whether the duper mutation alters parametric as well as nonparametric properties, intensity thresholds, and noncircadian responses to light. Furthermore, it assessed the effects of duper on the range of entrainment and circadian aftereffects. In the first study, duper mutant and wild-type (wt) hamsters showed a similar intensity threshold for light-induced phase shifts. In the second, wt, tau mutant, and super duper hamsters were exposed to LD cycles whose period (T) progressively shortened. Regardless of whether the light phase was held at 50% of T or fixed at 3 h, super duper mutants entrained to a wider range of T cycles and showed aftereffects upon release into DD. In the third study, LL was measured in mutant and wt hamsters that were maintained for 30-day intervals in constant light of progressively greater intensities. With increasing light intensity, the circadian period shortened in duper mutants. Circadian rhythms of super duper hamsters were disrupted at light intensities considerably below those that induced arrhythmicity in wt, tau heterozygote, or duper homozygote hamsters. In the fourth study, hamsters that were wt or homozygous for duper received two 15-min light pulses: the first at CT14 to CT16 or CT17 to CT19 and the second 2 h later. As expected, wt and duper mutants showed weak and strong resetting, respectively. Light pulses in early subjective night had an additive effect in mutant but not in wt hamsters, indicating that larger phase shifts of the pacemaker take longer to complete. Finally, super duper hamsters showed slightly but not significantly more negative masking than did wt or duper mutant hamsters. These results indicate that the duper mutation affects the properties of the central circadian pacemaker. The mutant allele affects not only the PRC but also parametric responses to light. © 2014 The Author(s). Source


Normanly J.,University of Massachusetts Amherst
Cold Spring Harbor perspectives in biology | Year: 2010

There is abundant evidence of multiple biosynthesis pathways for the major naturally occurring auxin in plants, indole-3-acetic acid (IAA), and examples of differential use of two general routes of IAA synthesis, namely Trp-dependent and Trp-independent. Although none of these pathways has been completely defined, we now have examples of specific IAA biosynthetic pathways playing a role in developmental processes by way of localized IAA synthesis, causing us to rethink the interactions between IAA synthesis, transport, and signaling. Recent work also points to some IAA biosynthesis pathways being specific to families within the plant kingdom, whereas others appear to be more ubiquitous. An important advance within the past 5 years is our ability to monitor IAA biosynthesis and metabolism at increasingly higher resolution. Source


Blanco M.B.,University of Massachusetts Amherst
American Journal of Physical Anthropology | Year: 2011

The small-bodied nocturnal mouse lemurs (genus Microcebus) occupy a variety of habitats in Madagascar. Gray (M. murinus) and brown (M. rufus) mouse lemurs have been widely studied both in the wild and captivity. Whereas captive studies revealed an endogenous regulation of reproduction entrained by photoperiod, field studies have suggested that reproductive activation could be affected by additional climatic, physical, or social conditions. I collected data on wild brown mouse lemur females at Ranomafana between 2004 and 2008 to determine: 1) the timing of estrus and estrous periodicities across multiple seasons, and 2) whether additional factors such as body mass, age, or rainfall are correlated with onset of reproduction. In mouse lemur females at Ranomafana, the first seasonal estrus occurs 3-4 weeks after the vernal equinox. I report ∼1 month's intra-population variation in the timing of estrus and inter-annual estrous intervals with periodicities of ∼365 days. There were significant differences between the onset of reproduction across years. Estrous onset was uncorrelated with body mass, but there was an apparent age effect. There was a significant negative correlation between August rainfall and onset of reproduction when 2004 data were removed from the analysis. Results from this study are consistent with the notion that timing of estrus is photoperiod-dependent. As in captivity, intra-population variation in estrous onset is ∼4 weeks in length. In the wild, variation in estrous onset and polyestry (multiple reproductive opportunities per year) appear to be favored under the highly unpredictable conditions of Madagascar's environments. In the wild, variation in estrous onset and polyestry (multiple reproductive opportunities per year) appear to be favored under the highly unpredictable conditions of Madagascar's environments. © 2011 Wiley-Liss, Inc. Source


Tremblay K.D.,University of Massachusetts Amherst
Journal of Cellular Physiology | Year: 2011

The endoderm emerges as an epithelial sheet that covers the surface of the developing murine embryo. This tissue will produce the entire gut tube as well as associated digestive and respiratory organs including the thyroid, thymus, lung, liver, and pancreas. The emergence of each endodermal organ occurs in a temporally distinct manner that is dependant upon reciprocal inductive interactions between the endoderm and the underlying mesoderm. The emergence of the hepatic endoderm, which occurs using a morphological process termed liver budding, initiates during early somitogenesis in the mouse at approximately 8.25 days post-coitum (dpc). Explant and transplant studies performed in chicken and mouse have demonstrated that secreted signals from adjacent mesodermal tissues initiate the hepatic gene program from ventral-fated endoderm. Here, we review the data in support of the roles of members of the fibroblast growth factor (FGF), bone morphogenetic protein (BMP), and Wnt signaling pathways in liver budding and discover that little is known about the precise endogenous signals involved in the molecular and morphological induction of liver budding in the mouse. © 2010 Wiley-Liss, Inc. Source


Rothstein J.P.,University of Massachusetts Amherst
Annual Review of Fluid Mechanics | Year: 2010

This review discusses the use of the combination of surface roughness and hydrophobicity for engineering large slip at the fluid-solid interface. These superhydrophobic surfaces were initially inspired by the unique water-repellent properties of the lotus leaf and can be employed to produce drag reduction in both laminar and turbulent flows, enhance mixing in laminar flows, and amplify diffusion-osmotic flows. We review the current state of experiments, simulations, and theory of flow past superhydrophobic surfaces. In addition, the designs and limitations of these surfaces are discussed, with an eye toward implementing these surfaces in a wide range of applications. Copyright © 2010 by Annual Reviews. All rights reserved. Source


Zhang G.,University of California at Davis | Zhang G.,University of Massachusetts Amherst | Kodani S.,University of California at Davis | Hammock B.D.,University of California at Davis
Progress in Lipid Research | Year: 2014

Epoxygenated fatty acids (EpFAs), which are lipid mediators produced by cytochrome P450 epoxygenases from polyunsaturated fatty acids, are important signaling molecules known to regulate various biological processes including inflammation, pain and angiogenesis. The EpFAs are further metabolized by soluble epoxide hydrolase (sEH) to form fatty acid diols which are usually less-active. Pharmacological inhibitors of sEH that stabilize endogenous EpFAs are being considered for human clinical uses. Here we review the biology of ω-3 and ω-6 EpFAs on inflammation, pain, angiogenesis and tumorigenesis. © 2013 Elsevier Inc. All rights reserved. Source


Noehren B.,University of Kentucky | Hamill J.,University of Massachusetts Amherst | Davis I.,Harvard University
Medicine and Science in Sports and Exercise | Year: 2013

PURPOSE: Patellofemoral pain (PFP) is the leading cause of knee pain in runners. Proximal and distal running mechanics have been linked to the development of PFP. However, the lack of prospective studies limits establishing a causal relationship of these mechanics to PFP. The purpose of this study was to prospectively compare running mechanics in a group of female runners who went on to develop PFP compared with healthy controls. It was hypothesized that runners who go on to develop PFP would exhibit greater hip adduction, hip internal rotation, and greater rear foot eversion. METHODS: Four hundred healthy female runners underwent an instrumented gait analysis and were then tracked for any injuries that they may have developed over a 2-yr period. Fifteen cases of PFP developed, which were confirmed by a medical professional. Their initial running mechanics were compared to an equal number of runners who remained uninjured. RESULTS: We found that female runners who developed PFP exhibited significantly greater hip adduction (P = 0.007). No statistically significant differences were found for the hip internal rotation angle (P = 0.47) or rear foot eversion (P = 0.1). CONCLUSIONS: The finding of greater hip adduction in female runners who develop PFP is in agreement with previous cross-sectional studies. These results suggest that runners who develop PFP use a different proximal neuromuscular control strategy than those who remain healthy. Injury prevention and treatment strategies should consider addressing these altered hip mechanics. Copyright © 2013 by the American College of Sports Medicine. Source


Calabrese E.J.,University of Massachusetts Amherst
Biogerontology | Year: 2013

This paper assesses the capacity of ionizing radiation to extend the lifespans of experimental insect models based on the peer-reviewed literature. Ionizing radiation biphasically affects the lifespans of adult males and females for a broad range of insect models with high doses reducing lifespan whereas lower doses can enhance lifespan, typically in the 20-60 % range. The average adult insect lifespan can be increased when ionizing radiation exposure is administered during early developmental stages or during the adult stage. The effective dose inducing the average adult insect lifespan enhancement may vary considerably depending upon which life stage is exposed. Recent findings have identified specific genes affecting anti-oxidant defenses, DNA repair, apoptosis and heat shock proteins as well as several cell signaling pathways that mediate the longevity enhancing hormetic response. © 2013 Springer Science+Business Media Dordrecht. Source


Carter K.R.,University of Massachusetts Amherst
ACS Nano | Year: 2010

Patterning of surfaces has evolved from ancient applications in printed text and art to a host of complex technological applications found today. The desire and ability to shrink patterns to molecular dimensions has enabled new powerful devices, and the need for improved patterning methods continues to be a major research thrust. Commonly referred to as lithographic processes, many advanced printing processes have no true relation to the original concept of lithography. A new paper in this issue of ACS Nano discusses a new form of printing that utilizes block copolymer assemblies as ink reservoirs for pattern transfer. The results show that truly nanometersized features can be reproduced accurately over large areas. The parallels to the original form of lithography are quite fascinating, and this new process, called "molecular transfer printing", may hold great promise as a new tool for nanoscale pattern replication. © 2010 American Chemical Society. Source


The intromittent organs of most amniotes contain variable-volume hydrostatic skeletons that are stored in a flexible state and inflate with fluid before or during copulation. However, the penis in male crocodilians is notable because its shaft does not seem to change either its shape or bending stiffness as blood enters its vascular spaces before copulation. Here I report that crocodilians may have evolved a mechanism for penile shaft erection that does not require inflation and detumescence. Dissections of the cloaca in sexually mature male American alligators (Alligator mississippiensis) show that the cross section of the proximal shaft of the alligator penis contains dense collagenous tissues that do not significantly change shape when fluid is added to the central vascular space. The large amount of collagen in the wall and central space of the alligator penis stiffen the structure so it can be simply everted for copulation and rapidly retracted at its completion. Because no muscles insert directly onto the penis, eversion and retraction must be produced indirectly. My results suggest that the contraction of paired levator cloacae muscles around the anterior end of the cloaca rotates the penis out of the cloacal opening and strains the ligamentum rami that connect the base of the penis to the ischia. When the cloacal muscles relax, the elastic recoil of the ligamentum rami can return the penis to its original position inside the cloaca. © 2013 Wiley Periodicals, Inc. Source


Calabrese E.J.,University of Massachusetts Amherst
Journal of Cell Communication and Signaling | Year: 2014

This issue of the Journal of Cell Communication and Cell Signaling on hormetic mechanisms represents an important step in the evolution of the hormesis dose response concept. Since its modern resurgence in the late 1970s the widespread occurrence of hormesis has been in search of its underlying mechanisms. The present integrative set of papers builds upon significant recent advances in the elucidation of hormetic mechanisms and provides the reader with a deep and extensive view of the concept of hormesis from a broad range of researcher perspectives and in many biomedical applications. © 2014, The International CCN Society. Source


Normark B.B.,University of Massachusetts Amherst | Ross L.,University of Edinburgh
Philosophical Transactions of the Royal Society B: Biological Sciences | Year: 2014

Genetic conflict may have played an important role in the evolution of novel genetic systems. The ancestral system of eumendelian genetics is highly symmetrical. Those derived from it (e.g. thelytokous parthenogenesis, haplodiploidy and parent-specific allele expression) are more asymmetrical in the genetic role played by maternal versus paternal alleles. These asymmetries may have arisen from maternal-paternal genetic conflict, or cytonuclear conflict, or from an interaction between them. Asymmetric genetic systems are much more common in terrestrial and freshwater taxa than in marine taxa. We suggest three reasons for this, based on the relative inhospitability of terrestrial environments to three types of organism: (i) pathogens-departure from the marine realm meant escape from many pathogens and parasites, reducing the need for sexual reproduction; (ii) symbionts-symbionts are no more important in the terrestrial realm than the marine realm but are more likely to be obligately intracellular and vertically transmitted, making them more likely to disrupt their host's genetic systems; (iii) Gametes and embryos-because neither gametes nor embryos can be shed into air as easily as into seawater, the mother's body is a more important environment for both types of organisms in the terrestrial realm than in the marine realm. This environment of asymmetric kinship (with neighbours more closely related by maternal alleles than by paternal alleles) may have helped to drive asymmetries in expression and transmission. © 2014 The Author(s) Published by the Royal Society. All rights reserved. Source


Calabrese E.J.,University of Massachusetts Amherst
Environmental pollution (Barking, Essex : 1987) | Year: 2013

The most common quantitative feature of the hormetic-biphasic dose response is its modest stimulatory response which at maximum is only 30-60% greater than control values, an observation that is consistently independent of biological model, level of organization (i.e., cell, organ or individual), endpoint measured, chemical/physical agent studied, or mechanism. This quantitative feature suggests an underlying "upstream" mechanism common across biological systems, therefore basic and general. Hormetic dose response relationships represent an estimate of the peak performance of integrative biological processes that are allometrically based. Hormetic responses reflect both direct stimulatory or overcompensation responses to damage induced by relatively low doses of chemical or physical agents. The integration of the hormetic dose response within an allometric framework provides, for the first time, an explanation for both the generality and the quantitative features of the hormetic dose response. Copyright © 2013 Elsevier Ltd. All rights reserved. Source


Borgerson C.,University of Massachusetts Amherst
International Journal of Primatology | Year: 2015

Threats to primates result from the complex relationship between ecological processes and the direct and the indirect impacts of humans. Yet we know little about the proportional impacts of hunting and changes to habitat on individual primate species. This knowledge is critical to effective conservation. I used primate surveys, habitat analysis, interviews, and one year of direct observation of hunter behavior and catch to compare the relative impacts of altered habitat and snare trapping on two sympatric lemur species: the two largest-bodied and most endangered lemurs on the Masoala peninsula of Madagascar, Varecia rubra (the red ruffed lemur; Critically Endangered) and Eulemur albifrons (the white-fronted brown lemur; Endangered). Results indicate that alteration of habitat and hunting shape local faunal communities in species-specific ways. While alteration of habitat had a greater effect than snare trapping on the populations of V. rubra, snare trapping had a greater effect than habitat on the populations of E. albifrons. Therefore conservation action plans for V. rubra and E. albifrons may benefit from individual tailoring. These findings illustrate the need to consider the different manners in which habitat change and hunting affect sympatric primate species when designing conservation policy. © 2015, Springer Science+Business Media New York. Source


Maroudas D.,University of Massachusetts Amherst
Surface Science Reports | Year: 2011

Surface morphological evolution under the action of external fields is a fascinating topic that has attracted considerable attention within the surface science community over the past two decades. In addition to the interest in a fundamental understanding of field-induced nonlinear response and stability of surface morphology, the problem has been technologically significant in various engineering applications such as microelectronics and nanofabrication. In this report, we review theoretical progress in modeling the surface morphological response of stressed elastic solids under conditions that promote surface diffusion and of electrically conducting solids under surface electromigration conditions. A self-consistent model of surface transport and morphological evolution is presented that has provided the basis for the theoretical and computational work that is reviewed. According to this model, the surface morphological response of electrically conducting elastic solids to the simultaneous action of mechanical stresses and electric fields is analyzed. Emphasis is placed on metallic surfaces, including surfaces of voids in metallic thin films. Surfaces of stressed elastic solids are known to undergo morphological instabilities, such as the AsaroTiller or Grinfeld (ATG) instability that leads to emanation of crack-like features from the surface and their fast propagation into the bulk of the solid material. This instability is analyzed theoretically, simulated numerically, and compared with experimental measurements. The surface morphological evolution of electrically conducting, single-crystalline, stressed elastic solids under surface electromigration conditions is also examined. We demonstrate that, through surface electromigration, a properly applied and sufficiently strong electric field can stabilize the surface morphology of the stressed solid against both crack-like ATG instabilities and newly discovered secondary rippling instabilities; the effects of important parameters, such as surface crystallographic orientation, on the surface morphological response to the simultaneous action of an electric field and mechanical stress also are reviewed. In addition, electromigration- driven surface morphological response is analyzed systematically, focusing on the current-driven surface morphological evolution of voids in metallic thin films; this analysis has been motivated largely by the crucial role of void dynamics in determining the reliability of metallic interconnects in integrated circuits and has led to the interpretation of a large body of experimental observations and measurements. The electromigration-driven translational motion of morphologically stable voids, effects of current-driven void dynamics on the evolution of the electrical resistance of metallic thin films, and current-driven voidvoid interactions also are reviewed. Furthermore, theoretical studies are reviewed that demonstrated very interesting current-driven nonlinear void dynamics in stressed metallic thin films, including the inhibition of electromigration-induced instabilities due to the action of biaxial tensile stress, and stress effects on the electromigration-driven translational motion of morphologically stable voids. Complex, oscillatory surface states under surface electromigration conditions have been observed in numerical studies. In this report, emphasis is placed on void surfaces in metallic thin films, for which stable time-periodic states have been demonstrated. It is shown that increasing parameters such as the electric-field strength or the void size past certain critical values leads to morphological transitions from steady to time-periodic states; the latter states are characterized by wave propagation on the surface of a void that migrates along the metallic film at constant speed. The transition onset corresponds to a Hopf bifurcation that may be either supercritical or subcritical, depending on the symmetry of the surface diffusional anisotropy as determined by the crystallographic orientation of the film plane. It is also shown that, in the case where the Hopf bifurcation is subcritical, the simultaneous action of mechanical stress leads the current-driven void morphological response to the stabilization of chaotic attractors; in such cases, as the applied stress level increases, the void dynamics is set on a route to chaos through a sequence of period-doubling bifurcations. The observation of current-driven chaotic dynamics in homoepitaxial islands also is discussed. © 2011 Elsevier B.V. All rights reserved. Source


Calabrese E.J.,University of Massachusetts Amherst
Wound Repair and Regeneration | Year: 2013

This paper provides a detailed historical assessment of the origin and developmental progress of the concept of wound healing and its attempted acceleration from its start in the beginning of the 20th century to approximately 1960. Emphasis is placed on the development of cell culture in the assessment of wound healing and in attempts to validate experimental findings via clinical research. Of particular interest were the observations that wound healing could be accelerated in the 30-50% range with the dose response displaying biphasic characteristics consistent with the hormesis dose-response model. Such findings set the stage for the hormetic dose-response revolution that is occurring within the biological and biomedical sciences, including wound healing, whereby considerable research now supports the capacity for endogenous and exogenous agents to accelerate the process of wound healing and its functional performance. © 2013 by the Wound Healing Society. Source


Wei L.-Y.,Microsoft | Wang R.,University of Massachusetts Amherst
ACM Transactions on Graphics | Year: 2011

Sampling is a core component for many graphics applications including rendering, imaging, animation, and geometry processing. The efficacy of these applications often crucially depends upon the distribution quality of the underlying samples. While uniform sampling can be analyzed by using existing spatial and spectral methods, these cannot be easily extended to general non-uniform settings, such as adaptive, anisotropic, or non-Euclidean domains. We present new methods for analyzing non-uniform sample distributions. Our key insight is that standard Fourier analysis, which depends on samples' spatial locations, can be reformulated into an equivalent form that depends only on the distribution of their location differentials. We call this differential domain analysis. The main benefit of this reformulation is that it bridges the fundamental connection between the samples' spatial statistics and their spectral properties. In addition, it allows us to generalize our method with different computation kernels and differential measurements. Using this analysis, we can quantitatively measure the spatial and spectral properties of various non-uniform sample distributions, including adaptive, anisotropic, and non-Euclidean domains. © 2011 ACM. Source


Calabrese E.J.,University of Massachusetts Amherst
Gerontology | Year: 2015

Hormesis is a biphasic dose response with specific quantitative features for the amplitude and width of the stimulation. It is highly generalizable and independent of biological model, endpoint, inducing agent, level of biological organization and mechanism. Hormesis may be induced via a direct stimulation or by overcompensation to a disruption of homeostasis. The induction of hormesis by low-level stressor agents not only rapidly upregulates adaptive processes to repair damage but also protects the adapted system from damage due to a subsequent challenging dose (toxic) within a definable temporal window. The striking consistency of the amplitude of hormetic response suggests that hormesis provides a quantitative description of biological plasticity. Knowledge of hormesis has particular potential biomedical significance with respect to slowing or retarding both normal aging processes and the progression of severe neurological diseases. © 2015 S. Karger AG, Basel Copyright © 2015, S. Karger AG. All rights reserved. Source


Dori-Hacohen G.,University of Massachusetts Amherst
Journal of Pragmatics | Year: 2012

This paper discusses the caller types in political talk radio programs in Israel and the United States. The different caller types are: anonymous, regular, returning, first-time and the unmarked standard caller. The regular callers in Israel use recognitionals to be identified by the host. The returning callers in both countries state their return at the beginning of their talk. The first-time caller also starts his interaction by stating this identity, and some of them say they are regular listeners, to mitigate their novice identity. These types are relevant throughout the interactions: the interactions with regulars and returning callers are harsher or freer than other interactions, whereas interactions with first time callers are gentler. These types resemble similar types from non-media environments, such as the barroom. The various caller membership types contribute to the construction of a community around the programs. © 2011. Source


McClements D.J.,University of Massachusetts Amherst
Journal of Food Science | Year: 2010

There is currently a lack of effective delivery systems to encapsulate, protect, and release bioactive lipophilic components, such as ω-3 fatty acids, conjugated linoleic acid, tributyrin, vitamins, antioxidants, carotenoids, and phytosterols, which is holding back the development of functional foods designed to combat diseases such as coronary heart disease, diabetes, hypertension, and cancer. Delivery systems consisting of lipid droplets encapsulated by nano-laminated biopolymer coatings have great potential for use in the food industry for the encapsulation, protection, and release of bioactive lipids. This article reviews the potential impact of the physicochemical characteristics of nano-laminated biopolymer coatings on the bioavailability of encapsulated lipids. The effects of layer thickness, composition, electrical charge, permeability, and environmental responsiveness on digestion, release, and absorption of lipophilic components are highlighted. The possibility of designing nano-laminated biopolymer coatings to increase, decrease, or control the bioavailability of encapsulated lipids is shown. Data generated from in vitro digestion models and animal feeding studies are presented. This knowledge could be used by the food industry to produce functional foods designed to improve human health and wellness. © 2009 Institute of Food Technologists®. Source


Starns J.J.,University of Massachusetts Amherst
Memory and Cognition | Year: 2014

Receiver operating characteristic (ROC) functions are often used to make inferences about memory processes, such as claiming that memory strength is more variable for studied versus nonstudied items. However, decision processes can produce the ROC patterns that are usually attributed to memory, so independent forms of data are needed to support strong conclusions. The present experiments tested ROC-based claims about the variability of memory evidence by modeling response time (RT) data with the diffusion model. To ensure that the model can correctly discriminate equal- and unequal-variance distributions, Experiment 1 used a numerousity discrimination task that had a direct manipulation of evidence variability. Fits of the model produced correct conclusions about evidence variability in all cases. Experiments 2 and 3 explored the effect of repeated learning trials on evidence variability in recognition and source memory tasks, respectively. Fits of the diffusion model supported the same conclusions about variability as the ROC literature. For recognition, evidence variability was higher for targets than for lures, but it did not differ on the basis of the number of learning trials for target items. For source memory, evidence variability was roughly equal for source 1 and source 2 items, and variability increased for items with additional learning attempts. These results demonstrate that RT modeling can help resolve ambiguities regarding the processes that produce different patterns in ROC data. The results strengthen the evidence that memory strength distributions have unequal variability across item types in recognition and source memory tasks. © 2014, Psychonomic Society, Inc. Source


Calabrese E.J.,University of Massachusetts Amherst
Human and Experimental Toxicology | Year: 2010

This paper summarizes numerous conceptual and experimental advances over the past two decades in the study of hormesis. Hormesis is now generally accepted as a real and reproducible biological phenomenon, being highly generalized and independent of biological model, endpoint measured and chemical class/physical stressor. The quantitative features of the hormetic dose response are generally highly consistent, regardless of the model and mechanism, and represent a quantitative index of biological plasticity at multiple levels of biological organization. The hormetic dose-response model has been demonstrated to make far more accurate predictions of responses in low dose zones than either the threshold or linear at low dose models. Numerous therapeutic agents widely used by humans are based on the hormetic dose response and its low dose stimulatory characteristics. It is expected that as low dose responses come to dominate toxicological research that risk assessment practices will incorporate hormetic concepts in the standard setting process. Source


Demery V.,University of Massachusetts Amherst
Nature Materials | Year: 2015

Elastic sheets offer a path to encapsulating a droplet of one fluid in another that is different from that of traditional molecular or particulate surfactants. In wrappings of fluids by sheets of moderate thickness with petals designed to curl into closed shapes, capillarity balances bending forces. Here, we show that, by using much thinner sheets, the constraints of this balance can be lifted to access a regime of high sheet bendability that brings three major advantages: ultrathin sheets automatically achieve optimally efficient shapes that maximize the enclosed volume of liquid for a fixed area of sheet; interfacial energies and mechanical properties of the sheet are irrelevant within this regime, thus allowing for further functionality; and complete coverage of the fluid can be achieved without special sheet designs. We propose and validate a general geometric model that captures the entire range of this new class of wrapped and partially wrapped shapes. © 2015 Nature Publishing Group Source


McClements D.J.,University of Massachusetts Amherst
Soft Matter | Year: 2012

Colloidal delivery systems based on microemulsions or nanoemulsions are increasingly being utilized in the food and pharmaceutical industries to encapsulate, protect, and deliver lipophilic bioactive components. The small size of the particles in these kinds of delivery systems (r < 100 nm) means that they have a number of potential benefits for certain applications: enhanced long-term stability; high optical clarity; and, increased bioavailability. Currently, there is considerable confusion about the use of the terms "microemulsions" and "nanoemulsions" in the scientific literature. However, these are distinctly different types of colloidal dispersions: a microemulsion is thermodynamically stable, whereas a nanoemulsion is not. It is therefore important to distinguish between them since this impacts the methods used to fabricate them, the strategies used to stabilize them, and the approaches used to design their functional attributes. This article reviews the differences and similarities between nanoemulsions and microemulsions in terms of their compositions, structure, fabrication, properties, and stability. It also attempts to highlight why there has been so much confusion in this area, and to clarify the terminology used to refer to these two kinds of colloidal dispersion. © 2012 The Royal Society of Chemistry. Source


Levin R.E.,University of Massachusetts Amherst
International Journal of Food Microbiology | Year: 2012

Unlike bacterial toxins that are primarily peptides and are therefore encoded by a single gene, fungal toxins such as the aflatoxins are multi-ring structures and therefore require a sequence of structural genes for their biological synthesis. There is therefore no specific PCR for any one of the four biologically produced aflatoxins. Unfortunately, the structural genes presently in use for PCR detection of aflatoxin producing fungi are also involved in the synthesis of other fungal toxins such as sterigmatocystin by Aspergillus versicolor and Aspergillus nidulans and therefore lack absolute specificity for aflatoxin producing fungi (Table1). In addition, the genomic presence of several structural genes involved in aflatoxin biosynthesis does not guarantee the production of aflatoxin by all isolates of Aspergillus flavus and Aspergillus parasiticus. The most widely used DNA target regions for discriminating Aspergillus species are those of the rDNA complex, mainly the internal transcribed spacer regions 1 and 2 (ITS1 and ITS2) and the variable regions in the 5'-end of the 28S rRNA gene. Since these sequence regions are unrelated to the structural genes involved in aflatoxin biosynthesis there successful amplification can be used for species identification but do not confirm aflatoxin production. This review therefore presents the various approaches and limitations in the use of the PCR in attempting to detect aflatoxin producing fungi. © 2012 Elsevier B.V. Source


Aksamija Z.,University of Massachusetts Amherst | Knezevic I.,University of Wisconsin - Madison
Physical Review B - Condensed Matter and Materials Physics | Year: 2014

We study lattice thermal transport in large-area polycrystalline graphene, such as the samples grown by chemical vapor deposition (CVD) of carbon on Cu. These systems are composed of single-crystalline grains with a broad range of sizes and crystal orientations, separated by atomically rough grain boundaries. We solve the phonon Boltzmann transport equation and calculate the thermal conductivity in each grain, including scattering from the grain boundary roughness. Thermal transport in the large-area sample is considered in the Corbino-membrane geometry, with heat flowing through a network of thermal resistors and away from a pointlike heat source. The thermal transport in polycrystalline graphene is shown to be highly anisotropic, depending on the individual properties of the grains (their size and boundary roughness), as well as on grain connectivity. Strongest heat conduction occurs along large-grain filaments, while the heat flow is blocked through regions containing predominantly small grains. We discuss how thermal transport in CVD graphene can be tailored by controlling grain disorder. © 2014 American Physical Society. Source


Carbone E.T.,University of Massachusetts Amherst | Zoellner J.M.,University of Virginia
Journal of the Academy of Nutrition and Dietetics | Year: 2012

Health literacy is defined as the degree to which individuals obtain, process, and understand basic health information and services to make informed health decisions. Health literacy is a stronger predictor of health than age, income, employment, education, and race. Although the field has grown during the past decade, most health literacy research does not explicitly focus on food or nutrition, and dietetics practitioners often remain unaware of patients' health literacy level. The purpose of this systematic review was to summarize the literature on nutrition and health literacy to enhance dietetics practitioners' awareness of the importance of health literacy in practice and research. Of the 33 studies reviewed, four focused on measurement development, 16 on readability assessments, and 13 on individual literacy skills assessments. Collective evaluation revealed four noteworthy gaps, including the need to use more comprehensive assessment approaches that move beyond readability and numeracy to address the full spectrum of health literacy factors; the need to apply more robust experimental studies to examine the effectiveness of health literacy interventions among individuals, communities, health care providers, and health care systems; the need to explore the moderating and mediating roles of an individual's health literacy status on nutrition outcomes; and the need to examine long-term effects of health literacy interventions on nutrition outcomes. This article defines health literacy gaps and opportunities in nutrition research and practice, and calls for continued action to elevate the role of dietetics practitioners in addressing health literacy. © 2012 by the Academy of Nutrition and Dietetics. Source


McClements D.J.,University of Massachusetts Amherst
Current Opinion in Colloid and Interface Science | Year: 2012

Emulsion science and technology has been used for many years to create a diverse range of commercial products, including pharmaceuticals, foods, agrochemicals, lubricants, personal care products, and cosmetics. The majority of these products are conventional emulsions consisting of droplets of one liquid dispersed in another immiscible liquid, e.g., oil-in-water emulsions. Recently, there has been growing interest in extending the functional performance of emulsion-based products using structural design principles. This article reviews recent developments in the creation of structured emulsions, including multiple emulsions, multilayer emulsions, colloidosomes, microclusters, filled hydrogel microspheres, and hybrid systems. The structure, fabrication, properties, and potential applications of each type of structured emulsion are discussed. In addition, recent advances in the fabrication of emulsion droplets with specific properties (size, charge, interfacial properties, and physical state) are also reviewed, since these are the basic building blocks of structured emulsions. © 2012 Elsevier Ltd. Source


Peleg M.,University of Massachusetts Amherst
Critical reviews in food science and nutrition | Year: 2012

The Arrhenius equation has been widely used as a model of the temperature effect on the rate of chemical reactions and biological processes in foods. Since the model requires that the rate increase monotonically with temperature, its applicability to enzymatic reactions and microbial growth, which have optimal temperature, is obviously limited. This is also true for microbial inactivation and chemical reactions that only start at an elevated temperature, and for complex processes and reactions that do not follow fixed order kinetics, that is, where the isothermal rate constant, however defined, is a function of both temperature and time. The linearity of the Arrhenius plot, that is, Ln[k(T)] vs. 1/T where T is in °K has been traditionally considered evidence of the model's validity. Consequently, the slope of the plot has been used to calculate the reaction or processes' "energy of activation," usually without independent verification. Many experimental and simulated rate constant vs. temperature relationships that yield linear Arrhenius plots can also be described by the simpler exponential model Ln[k(T)/k(T(reference))] = c(T-T(reference)). The use of the exponential model or similar empirical alternative would eliminate the confusing temperature axis inversion, the unnecessary compression of the temperature scale, and the need for kinetic assumptions that are hard to affirm in food systems. It would also eliminate the reference to the Universal gas constant in systems where a "mole" cannot be clearly identified. Unless proven otherwise by independent experiments, one cannot dismiss the notion that the apparent linearity of the Arrhenius plot in many food systems is due to a mathematical property of the model's equation rather than to the existence of a temperature independent "energy of activation." If T+273.16°C in the Arrhenius model's equation is replaced by T+b, where the numerical value of the arbitrary constant b is substantially larger than T and T(reference), the plot of Ln k(T) vs. 1/(T+b) will always appear almost perfectly linear. Both the modified Arrhenius model version having the arbitrary constant b, Ln[k(T)/k(T(reference)) = a[1/ (T(reference)+b)-1/ (T+b)], and the exponential model can faithfully describe temperature dependencies traditionally described by the Arrhenius equation without the assumption of a temperature independent "energy of activation." This is demonstrated mathematically and with computer simulations, and with reprocessed classical kinetic data and published food results. Source


Saldanha C.J.,Lehigh University | Saldanha C.J.,American University of Washington | Remage-Healey L.,University of Massachusetts Amherst | Schlinger B.A.,University of California at Los Angeles
Endocrine Reviews | Year: 2011

Sex steroids have long been recognized for their dramatic impact on brain and behavior, including rapid modulation of membrane excitability. It is a widely held perception that these molecules are largely derived from peripheral sources and lack the spatial and temporal specificity ascribed to classical neuromodulatory systems. Neuromodulatory systems, in contrast, are defined by their regulated neuronal presynaptic secretion and by their functional modulation of perisynaptic events. Here we provide evidence for regulated presynaptic estrogen synthesis and functional postsynaptic actions. These results meet all the criteria for a neuromodulatory system and shift our perception of estrogens from that of peripheral signals exclusively to include that of a signaling system intrinsic to the brain itself. We apply the term synaptocrine to describe this form of neuromodulation. © 2011 by The Endocrine Society. Source


Calabrese E.J.,University of Massachusetts Amherst
Archives of Toxicology | Year: 2013

This paper identifies the origin of the linearity at low-dose concept [i.e., linear no threshold (LNT)] for ionizing radiation-induced mutation. After the discovery of X-ray-induced mutations, Olson and Lewis (Nature 121(3052):673-674, 1928) proposed that cosmic/terrestrial radiation-induced mutations provide the principal mechanism for the induction of heritable traits, providing the driving force for evolution. For this concept to be general, a LNT dose relationship was assumed, with genetic damage proportional to the energy absorbed. Subsequent studies suggested a linear dose response for ionizing radiation-induced mutations (Hanson and Heys in Am Nat 63(686):201-213, 1929; Oliver in Science 71:44-46, 1930), supporting the evolutionary hypothesis. Based on an evaluation of spontaneous and ionizing radiation-induced mutation with Drosophila, Muller argued that background radiation had a negligible impact on spontaneous mutation, discrediting the ionizing radiation-based evolutionary hypothesis. Nonetheless, an expanded set of mutation dose-response observations provided a basis for collaboration between theoretical physicists (Max Delbruck and Gunter Zimmer) and the radiation geneticist Nicolai Timoféeff-Ressovsky. They developed interrelated physical science-based genetics perspectives including a biophysical model of the gene, a radiation-induced gene mutation target theory and the single-hit hypothesis of radiation-induced mutation, which, when integrated, provided the theoretical mechanism and mathematical basis for the LNT model. The LNT concept became accepted by radiation geneticists and recommended by national/ international advisory committees for risk assessment of ionizing radiation-induced mutational damage/cancer from the mid-1950s to the present. The LNT concept was later generalized to chemical carcinogen risk assessment and used by public health and regulatory agencies worldwide. © 2013 Springer-Verlag Berlin Heidelberg. Source


Mann G.S.,Google | McCallum A.,University of Massachusetts Amherst
Journal of Machine Learning Research | Year: 2010

In this paper, we present an overview of generalized expectation criteria (GE), a simple, robust, scalable method for semi-supervised training using weakly-labeled data. GE fits model parameters by favoring models that match certain expectation constraints, such as marginal label distributions, on the unlabeled data. This paper shows how to apply generalized expectation criteria to two classes of parametric models: maximum entropy models and conditional random fields. Experimental results demonstrate accuracy improvements over supervised training and a number of other state of- the-art semi-supervised learning methods for these models. © 2010 Gideon S. Mann and Andrew McCallum. Source


McClements D.J.,University of Massachusetts Amherst
Advances in Colloid and Interface Science | Year: 2012

Many bioactive components intended for oral ingestion (pharmaceuticals and nutraceuticals) are hydrophobic molecules with low water-solubilities and high melting points, which poses considerable challenges to the formulation of oral delivery systems. Oil-in-water emulsions are often suitable vehicles for the encapsulation and delivery of this type of bioactive component. The bioactive component is usually dissolved in a carrier lipid phase by either dilution and/or heating prior to homogenization, and then the carrier lipid and water phases are homogenized to form an emulsion consisting of small oil droplets dispersed in water. The successful development of this kind of emulsion-based delivery system depends on a good understanding of the influence of crystals on the formation, stability, and properties of emulsions. This review article addresses the physicochemical phenomena associated with the encapsulation, retention, crystallization, release, and absorption of hydrophobic bioactive components within emulsions. This knowledge will be useful for the rational formulation of effective emulsion-based delivery systems for oral delivery of crystalline hydrophobic bioactive components in the food, health care, and pharmaceutical industries. © 2012 Elsevier B.V. Source


Wexler L.,University of Massachusetts Amherst
Transcultural Psychiatry | Year: 2014

Research has established connection between indigenous culture - often described in terms of cultural identity, enculturation, and participation in traditional activities - and resilience, the process by which people overcome acute and ongoing challenges. Despite correlations between culture and resilience, research has seldom described the ways these concepts are linked in indigenous people's narratives. Furthermore, little attention has been paid to the affect of historical trauma on different generations' understanding and deployment of "culture" in the context of hardship. This project, conducted in the summer of 2008 in an indigenous Arctic community, focuses on narratives from three generations who have experienced different degrees of cultural suppression in their lifetimes. From this starting point, the study explores how individuals make meaning and take strength from particular notions of culture, and illuminates the ways each generation accesses and deploys their cultural understandings in the face of hardship. By identifying the similarities and differences in both the challenges and sources of strength for each generation, the paper highlights how understandings of culture are shaped by historical experiences and modified through time. The differing ways that culture fosters strength, purpose, and fortitude (or does not) in indigenous young people's, adults' and Elders' life stories provide clues for enhancing indigenous youth resilience. Findings suggest that "culture" can galvanize Inupiaq people's sense of identity, feeling of commitment, and purpose, all of which are protective. However, young people need support in developing particular ideas around cultural identity and group membership that can contribute to resilience. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav. Source


Looze D.P.,University of Massachusetts Amherst
European Journal of Control | Year: 2011

The effects of a controller on the residual wavefront variance in an adaptive optics system can be represented by a discrete-time system. Consequently, the controller design that minimizes the wavefront is given by the solution of a discrete-time Linear-Quadratic-Gaussian (LQG) problem. The purpose of this paper is to analyze the structure of the LQG controller that minimizes the residual wavefront variance. It is shown that the LQG controller is an integral controller when the DM has no dynamics, there is no computational delay (the total loop delay is one frame), and the PSD of the incident wavefront decreases by f-2 at all frequencies. Non-zero computational delays result in a multivariable generalization lead element being added to the controller with the zero of the lead element at the origin. © 2011 EUCA. Source


Chandler G.E.,University of Massachusetts Amherst
Journal for Nurses in Staff Development | Year: 2012

The transition from student to nurse has been described as traumatic, confusing, and shocking. The difficulties encountered by the graduates have led to the premature termination of their first position, and sometimes they leave nursing altogether. To coach new nurses in preparation for their first year of practice using an appreciative inquiry framework, this study focused on the new graduates' perspective of the processes that enabled them to successfully integrate into their new role. From the analysis of 36 interviews, three themes were identified: "They were there for me," "There are no stupid questions," and "Nurturing the seeds." New nurses know what works for them; educators need to heed their wisdom. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins. Source


Vandenberg L.N.,University of Massachusetts Amherst
Dose-Response | Year: 2014

Non-monotonic dose response curves (NMDRCs) have been demonstrated for natural hormones and endocrine disrupting chemicals (EDCs) in a variety of biological systems including cultured cells, whole organ cultures, laboratory animals and human populations. The mechanisms responsible for these NMDRCs are well known, typically related to the interactions between the ligand (hormone or EDC) and a hormone receptor. Although there are hundreds of examples of NMDRCs in the EDC literature, there are claims that they are not 'common enough' to influence the use of high-to-low dose extrapolations in risk assessments. Here, we chose bisphenol A (BPA), a well-studied EDC, to assess the frequency of non-monotonic responses. Our results indicate that NMDRCs are common in the BPA literature, occurring in greater than 20% of all experiments and in at least one endpoint in more than 30% of all studies we examined. We also analyzed the types of endpoints that produce NMDRCs in vitro and factors related to study design that influence the ability to detect these kinds of responses. Taken together, these results provide strong evidence for NMDRCs in the EDC literature, specifically for BPA, and question the current risk assessment practice where 'safe' low doses are predicted from high dose exposures. © 2014 University of Massachusetts. Source


Barbosa A.C.,University of Massachusetts Amherst
Journal of medicinal food | Year: 2010

The well-known health benefits of apples have been attributed in part to the presence of polyphenols and related antioxidant capacity. The consumption of apples could provide health benefits by reducing the risk for chronic diseases such as metabolic syndrome disease, including type 2 diabetes. Thus, the objective of this study was to investigate the phenolic-linked antihyperglycemia bioactive factors in aqueous and 12% ethanol extracts of peel and pulp from 10 different freshly harvested apple varieties commonly consumed in the United States. The extracts were analyzed for total soluble phenolics, 2,2-diphenyl-1-picrylhydrazyl-linked antioxidant activity, and their associated in vitro α-glucosidase and α-amylase inhibitory activities. In general, peel extracts had higher total soluble phenolic content and related antioxidant capacity than pulp extracts. Quercetin derivatives, protocatechuic acid, chlorogenic acid, and p-coumaric acid were detected, and the amount varied significantly between aqueous and ethanolic extracts. Honeycrisp and Red Delicious varieties had the highest total phenolic contents and a significant correlation with antioxidant capacity (r = 0.91). In addition, high α-amylase and α-glucosidase inhibitory activities in aqueous pulp extracts were found. However, the peel extracts had the highest α-glucosidase inhibitory activity along with low α-amylase inhibitory activity. No correlation between α-amylase inhibitory activity and total phenolic content was observed. However, positive correlations between α-glucosidase inhibitory activity and total phenolics in aqueous (r = 0.50) and ethanolic (r = 0.70) extracts were observed. This study provides the biochemical rationale for animal and clinical studies to determine the suitable varieties with optimum bioactive factors with antihyperglycemia potential. Source


Calabrese E.J.,University of Massachusetts Amherst
Environmental Pollution | Year: 2013

The most common quantitative feature of the hormetic-biphasic dose response is its modest stimulatory response which at maximum is only 30-60% greater than control values, an observation that is consistently independent of biological model, level of organization (i.e., cell, organ or individual), endpoint measured, chemical/physical agent studied, or mechanism. This quantitative feature suggests an underlying "upstream" mechanism common across biological systems, therefore basic and general. Hormetic dose response relationships represent an estimate of the peak performance of integrative biological processes that are allometrically based. Hormetic responses reflect both direct stimulatory or overcompensation responses to damage induced by relatively low doses of chemical or physical agents. The integration of the hormetic dose response within an allometric framework provides, for the first time, an explanation for both the generality and the quantitative features of the hormetic dose response. © 2013 Elsevier Ltd. All rights reserved. Source


Bradley B.A.,Amherst College | Bradley B.A.,University of Massachusetts Amherst | Blumenthal D.M.,U.S. Department of Agriculture | Wilcove D.S.,Princeton University | Ziska L.H.,U.S. Department of Agriculture
Trends in Ecology and Evolution | Year: 2010

The relationship between plant invasions and global change is complex. Whereas some components of global change, such as rising CO2, usually promote invasion, other components, such as changing temperature and precipitation, can help or hinder plant invasion. Additionally, experimental studies and models suggest that invasive plants often respond unpredictably to multiple components of global change acting in concert. Such variability adds uncertainty to existing risk assessments and other predictive tools. Here, we review current knowledge about relationships between plant invasion and global change, and highlight research needed to improve forecasts of invasion risk. Managers should be prepared for both expansion and contraction of invasive plants due to global change, leading to increased risk or unprecedented opportunities for restoration. © 2009 Elsevier Ltd. Source


Renski H.,University of Massachusetts Amherst
Papers in Regional Science | Year: 2011

This paper explores how external economies influence the survival of new, independent business establishments in the continental United States using a confidential, establishment-level dataset on new firm longevity. Industrial localization has a positive influence on new businesses survival in five of the eight industries examined. Regional industrial diversity is also beneficial to new firms in five study industries, particularly those that are more knowledge-intensive. The benefits of city size are limited to two study industries, with diseconomies of size found for an additional three. Resumen: Este artículo explora cómo influyen las economías externas en la supervivencia de nuevos establecimientos comerciales independientes en la parte continental de los EE.UU. y utiliza la longevidad de nuevas empresas incluida en un conjunto de datos confidencial a escala de establecimiento. La localización industrial tiene una influencia positiva en la supervivencia de nuevos negocios en cinco de los ocho sectores examinados. La diversidad industrial regional es también beneficiosa para las nuevas empresas de cinco de los sectores de estudio, en particular en los que dependen más del conocimiento. Los beneficios del tamaño de la ciudad están limitados a dos de los sectores estudiados, y se encontraron deseconomías de escala para tres sectores. © 2010 the author(s). Papers in Regional Science © 2010 RSAI. Source


Calabrese E.J.,University of Massachusetts Amherst
Environmental and Molecular Mutagenesis | Year: 2011

This paper reassessed studies conducted under the leadership of Drosophila geneticist Curt Stern which played a pivotal role in the acceptance of the linear dose-response model by the U.S. National Academy of Sciences Biological Effects of Atomic Radiation (BEAR) I Committee and the subsequent generalization of their recommendations on the linearity dose-response paradigm for ionizing radiation and chemically induced cancer. The analysis finds serious concerns and flaws in important aspects of these experiments, their assessment, and interpretation. Of particular concern was the failure of Stern's group to provide the necessary and promised experimental documentation to support the findings of three critical summarized experiments published as a brief technical note in Science. While this analysis questions the validity of the reported findings and their interpretations, it raises an even more serious concern about the process by which leaders in the radiation genetics community accepted such findings without requiring the necessary documentation and then used this information to support the acceptance of the linear dose-response in public policy matters as affected by risk assessment practices that have continued to the present. © 2011 Wiley-Liss, Inc. Source


In this tutorial review, we discuss the use of classical density functional theory (DFT) to understand adsorption/desorption hysteresis phenomena for fluids confined in mesoporous materials. The emphasis is on lattice gas models, for which DFT is especially straightforward when studies of the fluid density distribution in two and three dimensions are required. The theme is to show that much of the experimentally determined hysteresis phenomena can be described using this modeling framework. Several examples have been used to illustrate this, including a simple duct pore, a duct inkbottle and a model of Vycor glass. We discuss hysteresis in single pores in terms of the metastability of the vapor phase in the pore and extend this to systems with pore size distributions. Inkbottle geometries are used to illustrate the phenomena of pore blocking and cavitation. The model of Vycor shows how the DFT formalism can describe systems with disordered interconnected pore structures that lead to type H2 hysteresis. The calculation of scanning curves using DFT is described and the relationship between scanning curves and pore interconnectivity is discussed. By weakening the surface field the DFT approach can be used to describe systems with partial wetting (e.g. water in carbon pores) and partial drying (mercury porosimetry). Finally, a dynamic mean field theory is introduced and used to study the dynamics of capillary condensation in the duct pore and, in particular, the nucleation of the liquid phase via the formation of a liquid bridge between the pore walls. © 2012 Elsevier Inc. All rights reserved. Source


Wagner D.L.,University of Connecticut | Van Driesche R.G.,University of Massachusetts Amherst
Annual Review of Entomology | Year: 2010

Endangerment factors are reviewed for 57 U.S. federally listed insects and 116 rare eastern North American lepidopterans to determine the importance of invasive species relative to 15 other recognized endangerment factors. Invasive plants, social insects (especially ants), and vertebrate grazers and predators repeatedly were identified as groups directly or indirectly threatening native insect biodiversity. Among rare eastern North American lepidopterans, the (mostly indirect) consequences of the establishment of the gypsy moth (Lymantria dispar) surfaced as a general threat. Remote islands, especially those with high human visitation, stand out as being highly threatened by invasives. In the worst cases, impacts from invasive species cascade through a community and destabilize existing trophic interconnections and alter basic ecosystem properties, changing hydrology, nutrient cycles, soil chemistry, fire susceptibility, and light availability, and precipitate myriad other changes in biotic and abiotic parameters. Invasive ants and herbivorous insects provide some of the most dramatic examples of such insect-induced invasional cascades. © 2010 by Annual Reviews All rights reserved. Source


Charney N.D.,University of Massachusetts Amherst
Ecological Modelling | Year: 2012

When ecological models are used to guide conservation decisions, these models should be based upon substantial data and should be applied at appropriate spatial scales. Yet, ecologists are usually faced with scarce data and must often make subjective choices about scale. To handle limited data, the use of expert panels to parameterize models has become common. However, few studies evaluate the success of expert panels in improving models. In this study, I examine a recent resistant kernel model designed to prioritize amphibian breeding habitat for conservation. I compare the predictive ability of the model as originally parameterized by an expert panel to the predictive ability of simpler models. I optimize parameter values for spatial scale and landscape resistance using 896 ponds from 5 studies of spotted salamanders (Ambystoma maculatum) and wood frogs (Lithobates sylvaticus) in Massachusetts and Rhode Island. In predicting amphibian distributions, models examined in this study that relied upon expert-derived resistance values performed worse than null models with uninformative resistance values. The failure of the resistant kernel model offers support for the use of simple models in the face of complex ecological problems. The best scale for measuring upland habitat in these models was in the range of 1000-3000. m, an order of magnitude larger than the salamander migration scale previously proposed for wetland buffer zones. © 2012 Elsevier B.V. Source


Turner C.N.,University of Massachusetts Amherst
Library Resources and Technical Services | Year: 2014

Scholarly publishing is the information marketplace in which academic libraries Junction, and major shifts in traditional publishing and pricing models are in process. Library consortia have long been viewed as a means of increasing purchasing power and reducing costs. In late 2010, the Five College Libraries (FCL) hired R2 Consulting, LLC to investigate and make recommendations regarding how the Libraries cooperate more closely on the acquisition, management, and delivery of electronic resources. This study examines and evaluates how other academic library consortia are licensing and acquiring electronic books, databases, journals and streaming media. The organizations, activities, processes, history and trends of e-resource acquisitions and collection development at the Colorado Alliance of Research Libraries (CARL), Orbis Cascade Alliance (OCA), Triangle Research Libraries Network (TRLN) and Washington Research Library Consortium (WRLC) are presented with data collected by the author. Additional context is provided through a literature review, and a discussion of current practices provides a sampling of the new directions academic library consortia are taking and the challenges they face. Source


Sullivan F.R.,University of Massachusetts Amherst
Educational Technology and Society | Year: 2011

This paper presents the results of a micro-genetic analysis of the development of a creative solution arrived at by students working collaboratively to solve a robotics problem in a sixth-grade science classroom. Results indicate that four aspects of the enacted curriculum proved important to developing the creative solution, including the following: an open-ended, goal-oriented task; teacher modeling of inquiry techniques; provision of tools and an environment that allowed students to move between dual modes of interaction (seriousness and play); and provision of tools and an environment that allowed students to jointly develop a shared understanding achieved through tool-mediated, communicative, and cognitive interaction. The findings suggest that play is an important mode of inquiry if creativity is the learning goal. Implications of this research for the design of learning spaces as well as directions for future collaborative creativity research are discussed. © International Forum of Educational Technology & Society (IFETS). Source


Starns J.J.,University of Massachusetts Amherst | Ratcliff R.,Ohio State University
Journal of Memory and Language | Year: 2013

Recognition memory z-transformed Receiver Operating Characteristic (zROC) functions have a slope less than 1. One way to accommodate this finding is to assume that memory evidence is more variable for studied (old) items than non-studied (new) items. This assumption has been implemented in signal detection models, but this approach cannot accommodate the time course of decision making. We tested the unequal-variance assumption by fitting the diffusion model to accuracy and response time (RT) distributions from nine old/new recognition data sets comprising previously-published data from 376 participants. The η parameter in the diffusion model measures between-trial variability in evidence based on accuracy and the RT distributions for correct and error responses. In fits to nine data sets, η estimates were higher for targets than lures in all cases, and fitting results rejected an equal-variance version of the model in favor of an unequal-variance version. Parameter recovery simulations showed that the variability differences were not produced by biased estimation of the η parameter. Estimates of the other model parameters were largely consistent between the equal- and unequal-variance versions of the model. Our results provide independent support for the unequal-variance assumption without using zROC data. © 2013 Elsevier Inc.. Source


Walker E.L.,University of Massachusetts Amherst | Waters B.M.,University of Nebraska - Lincoln
Current Opinion in Plant Biology | Year: 2011

For human health, transition metal accumulation in edible seeds like cereal grains is of worldwide importance, since Fe and Zn deficiencies are among the most prevalent human nutritional disorders in the world. There have been many recent developments in our understanding of the patterns in which transition metals accumulate in the seeds, the identity of some specific transporters that are required for efficient seed metal accumulation, and the central role played by the ubiquitous plant metal chelator nicotianamine (NA). These and other recent discoveries will be reviewed here. © 2011 Elsevier Ltd. Source


Baskin T.I.,University of Massachusetts Amherst
Wiley Interdisciplinary Reviews: Developmental Biology | Year: 2013

Plasticity, the hallmark of plant morphogenesis, extends to kinetics. To enhance acclimation, growing plant organs adeptly adjust their growth rate, up or down. In roots, rates of division and elemental expansion as well as the length of division and elongation zones are readily characterized because of their linear organization, radial symmetry, and indeterminate growth, and can be measured accurately with kinematic methods. Here, for roots, I describe key concepts from kinematics and review patterns of growth and division during acclimation. The growth rate of a root reflects the integral of elemental expansion activity over the span of the growth zone; therefore, an acclimating plant can change the rate of root growth by changing either or both the span of the growth zone or the rate of elemental expansion. The analogous dichotomy exists for cell division where the rate at which cells are produced reflects the integral of cell division rate over the span of the division zone. Surprisingly, expansion responses nearly always involve changes in the length of the growth zone. Similarly, although based on fewer data, changes in cell division rate are rare, whereas changes in meristem length are common. These patterns imply that setting the boundaries for meristem and elongation zone is the key regulatory act for root growth rate acclimation. © 2012 Wiley Periodicals, Inc. Source


Logan J.M.,University of New Hampshire | Lutcavage M.E.,University of Massachusetts Amherst
Deep-Sea Research Part II: Topical Studies in Oceanography | Year: 2013

Pelagic ecosystems in the central North Atlantic Ocean support numerous commercially-exploited tuna, shark, and billfish species, which rely largely on cephalopod as well as fish and crustacean prey. Carbon and nitrogen stable isotope analyses were performed on tuna and billfish predators as well as cephalopod prey species sampled during two research longline cruises (2001-02) to study their trophic structure. Nitrogen stable isotope (δ15N) analyses revealed similarity in trophic position (TP) among sampled fish predator species, with large swordfish occupying the highest TP. Species with wider vertical distributions (swordfish and bigeye tuna) had higher δ15N values than species more constrained to the epipelagic zone (yellowfin tuna and dolphinfish). Analysis of tissue nitrogen isotope values showed an ontogenetic increase for swordfish and white marlin but no effects for other sampled fish species. For cephalopods as a group, δ15N increased with size. Smaller cephalopods sampled in this study had δ15N values that were about one TP below co-occurring tunas and billfishes, confirming their importance as a prey resource. Larger cephalopods had similar δ15N values to tunas and billfishes, indicating that these large cephalopods occupy a comparable TP to their fish predators. Both carbon and nitrogen stable isotope values of large pelagic fishes showed spatial gradients relative to conspecifics analyzed in coastal regions, which can be used to trace large scale movements. © 2012. Source


Goodwin S.E.,Graduate Program in Organismic and Evolutionary Biology | Podos J.,University of Massachusetts Amherst
Biology Letters | Year: 2014

Cooperation and conflict are regarded as diametric extremes of animal social behaviour, yet the two may intersect under rare circumstances. We here report that territorial competitors in a common North American songbird species, the chipping sparrow (Spizella passerina), sometimes form temporary coalitions in the presence of simulated territorial intruders. Moreover, analysis of birds' vocal mating signals (songs) reveals that coalitions occur nearly exclusively under specific triadic relationships, in which vocal performances of allies and simulated intruders exceed those of residents. Our results provide the first evidence that animals like chipping sparrows rely on precise assessments of mating signal features, as well as relative comparisons of signal properties among multiple animals in communication networks, when deciding when and with whom to form temporary alliances against a backdrop of competition and rivalry. © 2014 The Author(s) Published by the Royal Society. Source


Calabrese E.J.,University of Massachusetts Amherst
Environmental Toxicology and Chemistry | Year: 2011

This paper assesses how medicine adopted the threshold dose-response to evaluate health effects of drugs and chemicals throughout the 20th century to the present. Homeopathy first adopted the biphasic dose-response, making it an explanatory principle. Medicine used its influence to discredit the biphasic dose-response model to harm homeopathy and to promote its alternative, the threshold dose-response. However, it failed to validate the capacity of its model to make accurate predictions in the low-dose zone. Recent attempts to validate the threshold dose-response indicate that it poorly predicts responses below the threshold. The long marginalized biphasic/hormetic dose-response model made accurate predictions in these validation studies. The failure to accept the possibility of the hormetic-biphasic dose-response during toxicology's dose-response concept formative period, while adopting the threshold model, and later the linear no-threshold model for carcinogens, led toxicology to adopt a hazard assessment process that involved testing only a few very high doses. This created the framework that toxicology was a discipline that only studied harmful responses, ignoring the possibility of benefit at low doses by the induction of adaptive mechanisms. Toxicology needs to assess the entire dose-response continuum, incorporating both harmful and beneficial effects into the risk assessment process. © 2011 SETAC. Source


Ashkenazy H.,Tel Aviv University | Erez E.,Tel Aviv University | Martz E.,University of Massachusetts Amherst | Pupko T.,Tel Aviv University | Ben-Tal N.,Tel Aviv University
Nucleic Acids Research | Year: 2010

It is informative to detect highly conserved positions in proteins and nucleic acid sequence/structure since they are often indicative of structural and/or functional importance. ConSurf (http://consurf.tau. ac.il) and ConSeq (http://conseq.tau.ac.il) are two well-established web servers for calculating the evolutionary conservation of amino acid positions in proteins using an empirical Bayesian inference, starting from protein structure and sequence, respectively. Here, we present the new version of the ConSurf web server that combines the two independent servers, providing an easier and more intuitive step-by-step interface, while offering the user more flexibility during the process. In addition, the new version of ConSurf calculates the evolutionary rates for nucleic acid sequences. The new version is freely available at: http://consurf.tau.ac.il/. © The Author(s) 2010. Published by Oxford University Press. Source


Constantino M.J.,University of Massachusetts Amherst
Psychotherapy Research | Year: 2012

In this article I discuss one facet of my evolving research program focused on patients' psychotherapy-related expectations. Although generally considered a common psychotherapeutic factor, expectations have been historically undervalued conceptually, empirically, and clinically. Attempting to somewhat redress this slight, I will (a) define the various forms of patients' psychotherapy-related expectations, (b) present relevant findings from research that my colleagues, students, and I have conducted, (c) summarize an integrative psychotherapy approach that underscores expectations as an explanatory construct for patients' corrective experiences, and (d) highlight future research directions for increasing our understanding of the nature and functions of the expectancy construct. © 2012 Society for Psychotherapy Research. Source


Pan B.,Kunming University of Science and Technology | Xing B.,University of Massachusetts Amherst
European Journal of Soil Science | Year: 2012

The environmental application and risk assessment of manufactured nanoparticles (MNPs) in soil greatly depend on our understanding of the interactions between MNPs and soil components. Because of the complexity of the soil system and the very early stage of MNP research in soil, our understanding of MNP behaviour in this system is very limited. This review summarizes the progress of research on MNPs and their implications for soils. Manufactured nanoparticles are applied deliberately for soil remediation and are also released unintentionally through various other pathways to soil. Their colloidal behaviour in the soil system is discussed by analysing the effect of dissolved organic matter, light irradiation, water chemistry conditions and biological processes. The methods currently used for modelling MNP leaching and transport are summarized and several requirements for model improvement are proposed. The current topics regarding the environmental risks of MNPs (such as identifying the toxicity of MNPs and their dissolved ions, evidence that MNPs may be taken up by soil organisms or the risks of other pollutants as affected by the presence of MNPs) are described. Future research directions are discussed and proposed. © 2012 The Authors. Journal compilation © 2012 British Society of Soil Science. Source


Xia Q.,University of Massachusetts Amherst
Applied Physics A: Materials Science and Processing | Year: 2011

With CMOS scaling approaching its limits, there is a great need for advancements in novel devices, disruptive fabrication technologies, advanced materials and alternative computer architectures for future nanoelectronic systems. The emergence of memristive devices is one of promising solutions for the post-CMOS era. In this paper, we first introduce the fabrication of transition metal oxide based memristor cross-bars using nanoimprint lithography (NIL). The fabrication technique is further improved by using only one NIL step, reducing the fabrication efforts and improving the device performance. With shadow evaporation, a host of devices such as 2-terminal lateral memristors and 3-terminal memristive devices (memistors) are also demonstrated. By building memristor cross-bar arrays on foundrymade CMOS substrates using NIL, we have implemented hybrid nano/CMOS architecture. This hybrid chip provides an FPGA-like functionality with reconfigurable memristors defining data paths to wire logic gates into digital circuits. Future trends and issues with fabrication of memristive devices are also briefly discussed. © Springer-Verlag 2011. Source


Offner S.S.R.,University of Massachusetts Amherst | Arce H.G.,Yale University
Astrophysical Journal | Year: 2015

Observations of nearby molecular clouds detect shells, which are likely caused by winds from young main sequence stars. However, the progenitors of these observed features are not well characterized and the mass-loss rates inferred from the gas kinematics are several orders of magnitude greater than those predicted by atomic linedriven stellar wind models. We use magnetohydrodynamic simulations to model winds launching within turbulent molecular clouds and explore the impact of wind properties on cloud morphology and turbulence. We find that winds do not produce clear features in turbulent statistics such as the Fourier spectra of density and momentum but do impact the Fourier velocity spectrum. The density and velocity distribution functions, especially as probed by CO spectral lines, strongly indicate the presence and influence of winds. We show that stellar mass-loss rates for individual stars must be mw ≳10-7 M yr?1, similar to those estimated from observations, to reproduce shell properties. Consequently, we conclude that B and A-type main sequence stars have mass-loss rates several orders of magnitude larger that those predicted by models or that young stars are more variable than expected due to magnetic activity or accretion. © 2015. The American Astronomical Society. All rights reserved. Source


McClements D.J.,University of Massachusetts Amherst
Annual Review of Food Science and Technology | Year: 2010

The food industry has used emulsion science and technology for many years to create a diverse range of food products, such as milk, cream, soft drinks, nutritional beverages, dressings, mayonnaise, sauces, dips, deserts, ice cream, margarine, and butter. The majority of these food products are conventional oil-in-water (O/W) or water-in-oil (W/O) type emulsions. Recently, there has been increasing interest within the food industry in either improving or extending the functional performance of foods using novel structured emulsions. This article reviews recent developments in the creation of structured emulsions that could be used by the food and other industries, including nanoemulsions, multiple emulsions, multilayer emulsions, solid lipid particles, and filled hydrogel particles. These structured emulsions can be produced from food-grade generally recognized as safe (GRAS) ingredients (e.g., lipids, proteins, polysaccharides, surfactants, and minerals), using simple processing operations (e.g., mixing, homogenizing, and thermal processing). The structure, production, performance, and potential applications of each type of structured emulsion system are discussed. Copyright © 2010 by Annual Reviews. All rights reserved. Source


Lovley D.R.,University of Massachusetts Amherst
Energy and Environmental Science | Year: 2011

Microorganisms that can form direct electrical connections with insoluble minerals, electrodes, or other microorganisms can play an important role in some traditional as well as novel bioenergy strategies and can be helpful in the remediation of environmental contamination resulting from the use of more traditional energy sources. The surprising discovery that microorganisms in the genus Geobacter are capable of forming highly conductive networks of filaments that transfer electrons along their length with organic metallic-like conductivity, rather than traditional molecule to molecule electron exchange, provides an explanation for the ability of Geobacter species to grow in subsurface environments with insoluble Fe(iii) oxides as the electron acceptor, and effectively remediate groundwater contaminated with hydrocarbon fuels or uranium and similar contaminants associated with the mining and processing of nuclear fuel. A similar organic metallic-like conductivity may be an important mechanism for microorganisms to exchange electrons in syntrophic associations, such as those responsible for the conversion of organic wastes to methane in anaerobic digesters, a proven bioenergy technology. Biofilms with conductivities rivaling those of synthetic polymers help Geobacter species generate the high current densities in microbial fuel cells producing electric current from organic compounds. Electron transfer in the reverse direction, i.e. from electrodes to microbes, is the basis for microbial electrosynthesis, in which microorganisms reduce carbon dioxide to fuels and other useful organic compounds with solar energy in a form of artificial photosynthesis that is more efficient and avoids many of the environmental sustainability concerns associated with biomass-based bioenergy strategies. The ability of Geobacter species to produce highly conductive electronic networks that function in water opens new possibilities in the emerging field of bioelectronics. © The Royal Society of Chemistry 2011. Source


McClements D.J.,University of Massachusetts Amherst
Progress in Lipid Research | Year: 2013

Food-grade nanoemulsions are being increasingly used in the food and beverage industry to encapsulate, protect, and deliver hydrophobic functional components, such as oil-soluble flavors, colors, preservatives, vitamins, and nutraceuticals. These nanoemulsions contain lipid nanoparticles (radius <100 nm) whose physicochemical characteristics (e.g., composition, dimensions, structure, charge, and physical state) can be controlled by selection of appropriate ingredients and fabrication techniques. Nanoemulsions have a number of potential advantages over conventional emulsions for applications within the food industry: higher stability to particle aggregation and gravitational separation; higher optical transparency; and, increased bioavailability of encapsulated components. On the other hand, there are also some risks associated with consumption of lipid nanoparticles that should be considered before they are widely utilized, such as their ability to alter the fate of bioactive components within the gastrointestinal tract and the potential toxicity of some of the components used in their fabrication (e.g., surfactants and organic solvents). This article provides an overview of the current status of the biological fate and potential toxicity of food-grade lipid nanoparticles suitable for utilization within the food and beverage industry. © 2013 Elsevier Ltd. All rights reserved. Source


Starns J.J.,University of Massachusetts Amherst | Ratcliff R.,Ohio State University | McKoon G.,Ohio State University
Cognitive Psychology | Year: 2012

We tested two explanations for why the slope of the z-transformed receiver operating characteristic (zROC) is less than 1 in recognition memory: the unequal-variance account (target evidence is more variable than lure evidence) and the dual-process account (responding reflects both a continuous familiarity process and a threshold recollection process). These accounts are typically implemented in signal detection models that do not make predictions for response time (RT) data. We tested them using RT data and the diffusion model. Participants completed multiple study/test blocks of an " old" /" new" recognition task with the proportion of targets and the test varying from block to block (.21, .32, .50, .68, or .79 targets). The same participants completed sessions with both speed-emphasis and accuracy-emphasis instructions. zROC slopes were below one for both speed and accuracy sessions, and they were slightly lower for speed. The extremely fast pace of the speed sessions (mean RT = 526) should have severely limited the role of the slower recollection process relative to the fast familiarity process. Thus, the slope results are not consistent with the idea that recollection is responsible for slopes below 1. The diffusion model was able to match the empirical zROC slopes and RT distributions when between-trial variability in memory evidence was greater for targets than for lures, but missed the zROC slopes when target and lure variability were constrained to be equal. Therefore, unequal variability in continuous evidence is supported by RT modeling in addition to signal detection modeling. Finally, we found that a two-choice version of the RTCON model could not accommodate the RT distributions as successfully as the diffusion model. © 2011 Elsevier Inc. Source


Pocar A.,University of Massachusetts Amherst
Nuclear and Particle Physics Proceedings | Year: 2015

The search for neutrino-less double beta decay (0νDBD) is currently undertaken with experiments using 100's kg of candidate isotope in ultra low background detectors housed deep underground. We report on the recent data from the EXO-200 experiment on 0νDBD of 136Xe. We also summarise the goals of the future tonne-scale nEXO project, together with an overview of the R&D activities currently under way to make nEXO possible. © 2015 Elsevier B.V. Source


Lovley D.R.,University of Massachusetts Amherst
Environmental Microbiology Reports | Year: 2011

The discovery of electrotrophs, microorganisms that can directly accept electrons from electrodes for the reduction of terminal electron acceptors, has spurred the investigation of a wide range of potential applications. To date, only a handful of pure cultures have been shown to be capable of electrotrophy, but this process has also been inferred in many studies with undefined consortia. Potential electron acceptors include: carbon dioxide, nitrate, metals, chlorinated compounds, organic acids, protons and oxygen. Direct electron transfer from electrodes to cells has many advantages over indirect electrical stimulation of microbial metabolism via electron shuttles or hydrogen production. Supplying electrons with electrodes for the bioremediation of chlorinated compounds, nitrate or toxic metals may be preferable to adding organic electron donors or hydrogen to the subsurface or bioreactors. The most transformative application of electrotrophy may be microbial electrosynthesis in which carbon dioxide and water are converted to multi-carbon organic compounds that are released extracellularly. Coupling photovoltaic technology with microbial electrosynthesis represents a novel photosynthesis strategy that avoids many of the drawbacks of biomass-based strategies for the production of transportation fuels and other organic chemicals. The mechanisms for direct electron transfer from electrodes to microorganisms warrant further investigation in order to optimize envisioned applications. © 2010 Society for Applied Microbiology and Blackwell Publishing Ltd. Source


Calabrese E.J.,University of Massachusetts Amherst
EXS | Year: 2012

This chapter explores the historical foundations of hormesis, including the underlying reasons for its marginalization during most of the twentieth century and factors that are contributing to its resurgence and acceptance within the toxicological and pharmacological communities. Special consideration is given to the quantitative features of the hormetic dose response, as well as its capacity for generalization. Based on subsequent comparisons with other leading dose-response models, the hormesis dose response consistently provides more accurate predictions in the below threshold zone. It is expected that the hormetic dose response will become progressively more useful to the fields of toxicology, pharmacology, risk assessment, and the life sciences in general, especially where low-dose effects are of interest. Source


Pozrikidis C.,University of Massachusetts Amherst
Journal of Physics A: Mathematical and Theoretical | Year: 2016

A method is presented for computing the number of spanning trees involving one link or a specified group of links, and excluding another link or a specified group of links, in a network described by a simple graph in terms of derivatives of the spanning-tree generating function defined with respect to the eigenvalues of the Kirchhoff (weighted Laplacian) matrix. The method is applied to deduce the node degree distribution in a complete or randomized set of spanning trees of an arbitrary network. An important feature of the proposed method is that the explicit construction of spanning trees is not required. It is shown that the node degree distribution in the spanning trees of the complete network is described by the binomial distribution. Numerical results are presented for the node degree distribution in square, triangular, and honeycomb lattices. © 2016 IOP Publishing Ltd. Source


Aksamija Z.,University of Massachusetts Amherst | Knezevic I.,University of Wisconsin - Madison
Physical Review B - Condensed Matter and Materials Physics | Year: 2013

We investigate thermal transport in Si/Ge and Si1-xGe x/Si1-yGey alloy superlattices based on solving the single-mode phonon Boltzmann transport equation in the relaxation-time approximation and with full phonon dispersions. We derive an effective interface scattering rate that depends both on the interface roughness (captured by a wave-vector-dependent specularity parameter) and on the efficiency of internal scattering mechanisms (mass-difference and phonon-phonon scattering). We provide compact expressions for the calculations of in-plane and cross-plane thermal conductivities in superlattices. Our numerical results accurately capture both the observed increase in thermal conductivity as the superlattice period increases and the in-plane vs cross-plane anisotropy of thermal conductivity. Owing to the combined effect of interface and internal scattering, an alloy/alloy superlattice has a lower thermal conductivity than bulk SiGe with the same alloy composition. Thermal conductivity can be minimized by growing short-period alloy/alloy superlattices or Si/Si1-xGex superlattices with the SiGe layer thicker than the Si one. © 2013 American Physical Society. Source


Chao W.,University of Massachusetts Amherst
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015

We investigate an extension of the Standard Model (SM) with a U(1)′ gauge symmetry, which is spontaneously broken by a complex scalar singlet and where the new gauge boson is a stable dark matter candidate via a Z2 flavor symmetry. The possibility of generating a strongly first order electroweak phase transition (EWPT) needed for the electroweak baryogenesis mechanism in this model is studied using a gauge-independent method. Our result shows a considerable parameter space where both successful dark matter phenomenologies and a strongly first order electroweak phase transition can be achieved. © 2015 American Physical Society. Source


Chandra D.,University of Pennsylvania | Chandra D.,University of Massachusetts Amherst | Yang S.,University of Pennsylvania
Accounts of Chemical Research | Year: 2010

High aspect-ratio (HAR) micropillar arrays have many interesting and technologically important applications. Their properties, such as large mechanical compliance, large surface area, and a topography that is well-separated from the underlying substrate, have allowed researchers to design and explore biomimetic dry adhesives, superhydrophobic, superoleophobic, and tunable wetting surfaces, mechanical sensors and actuators, and substrates for cell mechanics studies. However, the mechanical compliance and large surface area of the micropillars also make these structures susceptible to deformation by adhesive and capillary surface forces. As a result such micropillars, particularly those made from soft polymers, can prove challenging to fabricate and to use in various applications. Systematic understanding of these forces is thus critical both to assemble stable micropillar arrays and to harness these surface forces toward controlled actuation for various applications. In this Account, we review our recent studies on the stability of HAR polymeric micropillar arrays against adhesive and capillary forces. Using the replica molding method, we have successfully fabricated HAR epoxy micropillar arrays with aspect ratios up to 18. The stability of these arrays against adhesive forces is in agreement with theoretical predictions. We have also developed a new two-step replica molding method to fabricate HAR (up to 12) hydrogel micropillar arrays using monomers or monomer mixtures. By varying the monomer composition in the fabrication process, we have fabricated a series of hydrogel micropillar arrays whose elastic moduli in wet state range from less than a megapascal to more than a gigapascal, and we have used these micropillar arrays to study capillary force induced clustering behavior as a function of the modulus. As a result, we have shown that as liquid evaporates off the micropillar arrays, the pillars bend and cluster together because of a much smaller capillary meniscus interaction force while the micropillar structures are surrounded by a continuous liquid body. Previously, researchers had often attributed this clustering effect to a Laplace pressure difference because of isolated capillary bridges. Our theoretical analysis of stability against capillary force and micropillar cluster size as a function of pillar elastic modulus agrees well with our experimental observations. The fabrication approaches presented here are quite general and will enable the fabrication of tall, stable micropillar arrays in a variety of soft, responsive materials. Therefore, researchers can use these materials for various applications: sensors, responsive wetting, and biological studies. The new insights into the capillary force induced clustering of micropillar arrays could improve rational design and fabrication of micropillar arrays that are stable against capillary force. In addition, these results could help researchers better manipulate capillary force to control the assembly of micropillar arrays and actuate these structures within novel devices. © 2010 American Chemical Society. Source


Wakai T.,University of Massachusetts Amherst
Cold Spring Harbor perspectives in biology | Year: 2011

Changes in the intracellular concentration of calcium ([Ca(2+)](i)) represent a vital signaling mechanism enabling communication among cells and between cells and the environment. The initiation of embryo development depends on a [Ca(2+)](i) increase(s) in the egg, which is generally induced during fertilization. The [Ca(2+)](i) increase signals egg activation, which is the first stage in embryo development, and that consist of biochemical and structural changes that transform eggs into zygotes. The spatiotemporal patterns of [Ca(2+)](i) at fertilization show variability, most likely reflecting adaptations to fertilizing conditions and to the duration of embryonic cell cycles. In mammals, the focus of this review, the fertilization [Ca(2+)](i) signal displays unique properties in that it is initiated after gamete fusion by release of a sperm-derived factor and by periodic and extended [Ca(2+)](i) responses. Here, we will discuss the events of egg activation regulated by increases in [Ca(2+)](i), the possible downstream targets that effect these egg activation events, and the property and identity of molecules both in sperm and eggs that underpin the initiation and persistence of the [Ca(2+)](i) responses in these species. Source


Ramasubramaniam A.,University of Massachusetts Amherst | Naveh D.,Bar - Ilan University
Physical Review B - Condensed Matter and Materials Physics | Year: 2013

We investigate the electronic and magnetic properties of Mn-doped monolayer MoS2 using a combination of first-principles density functional theory (DFT) calculations and Monte Carlo simulations. Mn dopants that are substitutionally inserted at Mo sites are shown to couple ferromagnetically via a double-exchange mechanism. This interaction is relatively short ranged, making percolation a key factor in controlling long-range magnetic order. The DFT results are parameterized using an empirical model to facilitate Monte Carlo studies of concentration- and temperature-dependent ordering in these systems, through which we obtain Curie temperatures in excess of room temperature for Mn doping in the range of 10-15%. Our studies demonstrate the potential for engineering a new class of atomically thin dilute magnetic semiconductors based on Mn-doped MoS2 monolayers. © 2013 American Physical Society. Source


Pollet L.,Ludwig Maximilians University of Munich | Prokof'Ev N.,Ludwig Maximilians University of Munich | Prokof'Ev N.,University of Massachusetts Amherst | Prokof'Ev N.,RAS Research Center Kurchatov Institute
Physical Review Letters | Year: 2012

We present solid evidence for the existence of a well-defined Higgs amplitude mode in two-dimensional relativistic field theories based on analytically continued results from quantum Monte Carlo simulations of the Bose-Hubbard model in the vicinity of the superfluid-Mott insulator quantum critical point, featuring emergent particle-hole symmetry and Lorentz invariance. The Higgs boson, seen as a well-defined low-frequency resonance in the spectral density, is quickly pushed to high energies in the superfluid phase and disappears by merging with the broad secondary peak at the characteristic interaction scale. Simulations of a trapped system of ultracold Rb87 atoms demonstrate that the low-frequency resonance is lost for typical experimental parameters, while the characteristic frequency for the onset of a strong response is preserved. © 2012 American Physical Society. Source


Nyachuba D.G.,University of Massachusetts Amherst
Nutrition Reviews | Year: 2010

Foodborneillness isaserious public health threat. TheCenters for DiseaseControland Prevention (CDC) estimates that 76 million foodborne illnesses, including 325,000 hospitalizations and 5,000 deaths, occur in the United States each year. Two recently published Foodborne Diseases Active Surveillance Network (FoodNet) reports showed that Salmonella, Campylobacter, Shigella, Cryptosporidium, and Shiga toxin Escherichia coli (STEC) O157 continue to be leading causes of both the number and incidence of laboratory-confirmed foodborne infections in the United States. According to the United States Department of Agriculture (USDA), foodborne illness costs theUS economy$10-83billion per year. Recent largefoodborne outbreakshave led to claims that the number of foodborne disease outbreaks and concomitant illnesses has increased in recent years. However, a comparison of data from the CDC showed very little change in the incidence of foodborne illness caused by common pathogens between 2008 and the preceding 3 years (2005-2007). Nevertheless, despite intensified prevention efforts, foodborne illness remains a persistent problem in the United States. Foodcanbecomecontaminatedatany point in the farm-to-table continuum, as well as in consumers' own kitchens. Therefore, foodborne illness risk reduction and control interventionsmust be implemented at every step throughout the food preparation process, from farm to table. In addition, more effective food safety education programs for foodhandlers and consumers are needed. Strategies should take into account food safety-related trends including large-scale production and wide distribution of food, globalization of the food supply, eating outside of the home, emergence of new pathogens, and growing population of at-risk consumers. © 2010 International Life Sciences Institute. Source


Balch J.K.,Pennsylvania State University | Balch J.K.,National Center for Ecological Analysis And Synthesis | Bradley B.A.,University of Massachusetts Amherst | D'Antonio C.M.,University of California at Santa Barbara | Gomez-Dans J.,University College London
Global Change Biology | Year: 2013

Non-native, invasive grasses have been linked to altered grass-fire cycles worldwide. Although a few studies have quantified resulting changes in fire activity at local scales, and many have speculated about larger scales, regional alterations to fire regimes remain poorly documented. We assessed the influence of large-scale Bromus tectorum (hereafter cheatgrass) invasion on fire size, duration, spread rate, and interannual variability in comparison to other prominent land cover classes across the Great Basin, USA. We compared regional land cover maps to burned area measured using the Moderate Resolution Imaging Spectroradiometer (MODIS) for 2000-2009 and to fire extents recorded by the USGS registry of fires from 1980 to 2009. Cheatgrass dominates at least 6% of the central Great Basin (650 000 km2). MODIS records show that 13% of these cheatgrass-dominated lands burned, resulting in a fire return interval of 78 years for any given location within cheatgrass. This proportion was more than double the amount burned across all other vegetation types (range: 0.5-6% burned). During the 1990s, this difference was even more extreme, with cheatgrass burning nearly four times more frequently than any native vegetation type (16% of cheatgrass burned compared to 1-5% of native vegetation). Cheatgrass was also disproportionately represented in the largest fires, comprising 24% of the land area of the 50 largest fires recorded by MODIS during the 2000s. Furthermore, multi-date fires that burned across multiple vegetation types were significantly more likely to have started in cheatgrass. Finally, cheatgrass fires showed a strong interannual response to wet years, a trend only weakly observed in native vegetation types. These results demonstrate that cheatgrass invasion has substantially altered the regional fire regime. Although this result has been suspected by managers for decades, this study is the first to document recent cheatgrass-driven fire regimes at a regional scale. © 2012 Blackwell Publishing Ltd. Source


Muthukumar M.,University of Massachusetts Amherst
Protein and Peptide Letters | Year: 2014

When macromolecules such as proteins are forced to translocate through a narrow pore, their conformational entropy is reduced, resulting in a free energy barrier. This free energy barrier is additionally modulated by protein-pore interactions. Furthermore, the driving force of the translocation such as the electrochemical potential gradient and electroosmotic flow navigates the transport of the protein through the free energy landscape. Depending on the specifics of the protein-pore system and the driving force, the details of the translocation process and their statistical properties such as the average translocation time can vary significantly. Nevertheless, there are a few fundamental physical concepts that underly the ubiquitous phenomenon of polymer translocation, which are reviewed here. © 2014 Bentham Science Publishers. Source


Winter H.H.,University of Massachusetts Amherst
Macromolecules | Year: 2013

This is a comparative study in search for common patterns in the relaxation dynamics of amorphous materials in the approach of a liquid-to-solid transition from the liquid side. Observations with two representative materials provide guidance for the study. The first material, a concentrated colloidal suspension, represents the glass transition. The second material is a cross-linking polymer far above its glass transition; it represents gelation. The entire study is founded in Boltzmann's constitutive equation of linear viscoelasticity; the stress is caused by a wide range of relaxation modes where, as argued here, fast modes dominate gelation and slow modes dominate the glass transition. For both classes of amorphous materials, the relaxation time spectrum broadens and adopts powerlaw format, but the powerlaw exponent is positive for the glass transition and negative for gelation, i.e. the relaxation patterns of gelling fluids and glass formers are inverse near the transition. Several examples are shown for each class of materials in order to test the proposed transition behavior for glasses (colloidal and molecular) on the one side and chemical/physical gels on the other. Among several results, this experimental study provides a decisive criterion that distinguishes the glass transition from gelation. It also shows a relation between the zero shear viscosity and the diverging longest relaxation time for both materials. © 2013 American Chemical Society. Source


Vanasse J.,University of Massachusetts Amherst
Physical Review C - Nuclear Physics | Year: 2012

We calculate the parity-violating amplitudes in the nd interaction with pionless effective field theory to leading order. Matching the parity-violating low-energy constants to the coefficients of the model by Desplanques, Donoghue, and Holstein we make numerical predictions for parity-violating observables. In particular, we give predictions for the spin rotation of a neutron on a deuteron target and for target and beam asymmetries in nd scattering. © 2012 American Physical Society. Source


Cooke M.L.,University of Massachusetts Amherst | Van Der Elst N.J.,University of California at Santa Cruz
Geophysical Research Letters | Year: 2012

New rheological data for wet kaolin support its use in analog table-top experiments that simulate deformation of the Earth's crust. Creep tests at small strain reveal that wet kaolin (62-66% water by mass) exhibits both elastic and viscous deformation characteristic of a Burger's material. When sheared to failure, the shear strength is relatively insensitive to the strain rate. The shear strength appears sensitive to the amount of initial compaction within the rheometer, which may indicate a normal-stress dependency typical of frictional materials. Stepped velocity tests at large strain demonstrate velocity weakening rate and state frictional behavior after yielding. Because the wet kaolin exhibits deformation characteristic of both frictional materials and bi-viscous materials, this material is well suited to simulate a variety of crustal deformational processes in scaled analog experiments. Copyright 2012 by the American Geophysical Union. Source


Mahler S.V.,Medical University of South Carolina | Moorman D.E.,Medical University of South Carolina | Moorman D.E.,University of Massachusetts Amherst | Smith R.J.,Medical University of South Carolina | And 2 more authors.
Nature Neuroscience | Year: 2014

Orexins (hypocretins) are two peptides (orexin A and B) produced from the pre-pro-orexin precursor and expressed in a limited region of dorsolateral hypothalamus. Orexins were originally thought to specifically mediate feeding and promote wakefulness, but it is now clear that they participate in a wide range of behavioral and physiological processes under select circumstances. Orexins primarily mediate behavior under situations of high motivational relevance, such as during physiological need states, exposure to threats or reward opportunities. We hypothesize that many behavioral functions of orexins (including regulation of sleep/wake cycling) reflect a fundamentally integrated function for orexins in translating motivational activation into organized suites of psychological and physiological processes supporting adaptive behaviors. We also discuss how numerous forms of neural heterogeneity modulate this function, allowing orexin neurons to organize diverse, adaptive responses in a variety of motivationally relevant situations. Thus, the involvement of orexins in diverse behaviors may reflect a common underlying function for this peptide system. © 2014 Nature America, Inc. All rights reserved. Source


Novel pentafluorophenyl (PFP)-ester-functionalized phosphorylcholine (PC) polymers of different architectures were prepared and conjugated to lysozyme as a model protein. Linear and two-arm poly(2-methacryloyloxyethyl phosphorylcholine) (polyMPC) structures containing PFP functionality at the chain-end were prepared by atom transfer radical polymerization (ATRP) from novel initiators. Additional conjugates were prepared from phosphorylcholine-substituted cyclooctene (PC-COE) polymers containing PFP-ester bearing comonomers. The polymer-protein conjugates were characterized by HPLC, FPLC, and DLS and were seen to retain most (~80% or greater) of their native enzymatic activity. Pharmacokinetic profiles of the polymer-protein conjugates were studied in mice and found to increase the circulation half-life compared with lysozyme alone. Source


Anber M.M.,University of Toronto | Sorbo L.,University of Massachusetts Amherst
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2012

In a previous paper, we proposed a model where natural inflation is realized on a steep potential [V()∼cos(/f) with fM P] as a consequence of the interaction of the inflaton with gauge fields through the coupling F μνFμν. In the present work we study the non-Gaussianities and the spectrum of tensor modes generated in this scenario. The non-Gaussianities turn out to be compatible with current observations and can be large enough to be detectable by Planck. The nonobservation of tensor modes imposes new constraints on the parameter space of the system that are about one order of magnitude stronger than those found in our previous paper. More importantly, in certain regions of the parameter space, tensor modes might be detected by upcoming cosmic microwave background (CMB) experiments even if inflation occurs at energies as low as the TeV scale. In this case the tensor modes would be chiral, and would lead to distinctive parity-violating correlation functions in the CMB. © 2012 American Physical Society. Source


Calabrese E.J.,University of Massachusetts Amherst
Experimental Gerontology | Year: 2013

The field of toxicology adopted the threshold dose response in the early decades of the 20th century. The model was rapidly incorporated into governmental regulatory assessment procedures and became a central feature of chemical evaluation and assessment. The toxicological community never validated the capacity of this model to make accurate predictions throughout the remainder of the 20th century. A series of recent investigations have demonstrated that the threshold and linear dose response model failed to make accurate predictions in the low dose zone. Such findings demonstrate a profound failure by the toxicology community on the central pillar of its discipline and one with profound public health, medical and economic implications. Ironically, the hormetic dose response, which was rejected by the toxicology community during the early decades of the 20th century, accurately predicted responses in the low dose zone in the same three large-scale validation assessments. Within the past two decades hormetic dose responses have been frequently reported in the experimental biogerontology literature, associated with endpoints associated enhancing healthy aging and longevity. The low dose stimulatory response of the hormetic dose response model represents the quantification of enhanced biological performance in the experimental facilitation of aging quality via multiple endpoints and mechanisms and in the extension of lifespan in such animal models research. © 2012 Elsevier Inc. Source


Anderson B.N.,Boston University | Muthukumar M.,University of Massachusetts Amherst | Meller A.,Boston University
ACS Nano | Year: 2013

Controlling DNA translocation speed is critically important for nanopore sequencing as free electrophoretic threading is far too rapid to resolve individual bases. A number of promising strategies have been explored in recent years, largely driven by the demands of next-generation sequencing. Engineering DNA-nanopore interactions (known to dominate translocation dynamics) with organic coatings is an attractive method as it does not require sample modification, processive enzymes, or complicated and expensive fabrication steps. In this work, we show for the first time 4-fold tuning of unfolded, single-file translocation time through small, amine-functionalized solid-state nanopores by varying the solution pH in situ. Additionally, we develop a simple analytical model based on electrostatic interactions to explain this effect which will be a useful tool in designing future devices and experiments. © 2012 American Chemical Society. Source


Frisk M.G.,State University of New York at Stony Brook | Jordaan A.,University of Massachusetts Amherst | Miller T.J.,University of Maryland Center for Environmental science
Fish and Fisheries | Year: 2014

During the past century, the field of fisheries oceanography has dominated the study of population connectivity in marine environments. The influence of physical and biological processes and their relationship to transport and retention of early life history stages has been central in providing insight into population structuring and connectivity. However, the focus on dispersive early life history stages has meant that the role of adults has received less attention and is not fully understood or appreciated. We argue that adults play a vital role in population connectivity for a wide range of marine taxa and hypothesize that adult-mediated population connectivity commonly results in a diverse array of population structuring. Two case-studies on winter skate, Leucoraja ocellata, and winter flounder, Pseudopleuronectes americanus, are presented to illustrate the role adults play in marine connectivity at both broad and fine scales, respectively. Indeed, if adults are important for population connectivity, we argue that the role of larval processes is conditional on adult choice and only management and research pursuits that integrate the full life cycle of species will capture the full dynamics of metapopulation connectivity. Failure to include the roles of adults can lead to misinterpretation of the causes and consequences of changes in ecosystem structure and fisheries productivity. © 2013 John Wiley & Sons Ltd. Source


Croll A.B.,North Dakota State University | Crosby A.J.,University of Massachusetts Amherst
Macromolecules | Year: 2012

When an elastic plate is fixed to a soft substrate and compressed, it accommodates applied strain by buckling and forming a sinusoidally wrinkled topography. At large strains, the regular wrinkled pattern is replaced by sharp, localized folds. Such folds are ubiquitous in biology; however, strains are not necessarily large in all cases, suggesting that a different mechanism may contribute to the formation of folds. In this work, we use thin films of a symmetric diblock copolymer coupled to thick elastomer substrates to explore the progression from isotropic wrinkles to localized folds in films with secondary structure. The block copolymer molecules organize into lamellae parallel to the elastomer substrate, and the balance of film thickness, lamellar dimensions, and elasticity dictate the development of topographic structures in a systematic manner. This "self-assembled" topography in the bounding film leads to stress localization when the pattern has a lateral spacing of the same order as the wrinkling wavelength. This first systematic exploration of pattern driven localization reveals the importance of a new emergent length scale which also appears in more traditional localization experiments. © 2012 American Chemical Society. Source


Wolf T.,University of Massachusetts Amherst
IEEE Transactions on Education | Year: 2010

Laboratory experience is a key factor in technical and scientific education. Virtual laboratories have been proposed to reduce cost and simplify maintenance of lab facilities while still providing students with access to real systems. It is important to determine if such virtual labs are still effective for student learning. In the assessment of a graduate computer networks course, the author quantifies the amount of learning that is observed in lectures and labs. The results not only show that learning indeed occurs during lab sessions, but almost equally as much (45.9%) as in lectures (54.1%). Also, it is observed that even students who have prior experience in networking benefit from virtual labs. © 2009 IEEE. Source


Hua G.,Jones Edmunds and Associates Inc. | Reckhow D.A.,University of Massachusetts Amherst
Water Research | Year: 2012

Bromine substitution factor (BSF) was used to quantify the effects of disinfectant dose, reaction time, pH, and temperature on the bromine substitution of disinfection byproducts (DBPs) during chlorination and chloramination. The BSF is defined as the ratio of the bromine incorporated into a given class of DBPs to the total concentration of chlorine and bromine in that class. Four classes of DBPs were evaluated: trihalomethanes (THMs), dihaloacetonitriles (DHANs), dihaloacetic acids (DHAAs) and trihaloacetic acids (THAAs). The results showed that the BSFs of the four classes of DBPs generally decreased with increasing reaction time and temperature during chlorination at neutral pH. The BSFs peaked at a low chlorine dose (1 mg/L) and decreased when the chlorine dose further increased. The BSFs of chlorination DBPs at neutral pH are in the order of DHAN > THM & DHAA > THAA. DHAAs formed by chloramines exhibited distinctly different bromine substitution patterns compared to chlorination DHAAs. Brominated DBP formation was generally less affected by the pH change compared to chlorinated DBP formation. © 2012 Elsevier Ltd. Source


Maresca T.J.,University of Massachusetts Amherst
Current Biology | Year: 2011

Separating mitotic error correction, chromosome biorientation and the spindle assembly checkpoint (SAC) is complicated by their interconnected relationships. New research finds that Aurora B kinase, which drives error correction and promotes biorientation, also directly regulates the SAC. © 2011 Elsevier Ltd All rights reserved. Source


Braakman I.,University Utrecht | Hebert D.N.,University of Massachusetts Amherst
Cold Spring Harbor Perspectives in Biology | Year: 2013

In this article, we will cover the folding of proteins in the lumen of the endoplasmic reticulum (ER), including the role of three types of covalent modifications: signal peptide removal, Nlinked glycosylation, and disulfide bond formation, aswell as the function and importance of resident ER folding factors. These folding factors consist of classical chaperones and their cochaperones, the carbohydrate-binding chaperones, and the folding catalysts of the PDI and proline cis-trans isomerase families. We will conclude with the perspective of the folding protein: a comparison of characteristics and folding and exit rates for proteins that travel through the ER as clients of the ER machinery. © 2013 Cold Spring Harbor Laboratory Press; all rights reserved. Source


Little is known about the development of the sensory systems of wolves. The timing of sensory development in wolves is usually extrapolated from studies on dogs, since they are members of the same species. However, early developmental differences between these two subspecies have already been identified. For example, wolves tend to approach and investigate objects in their environment 2 wk before dogs. These changes in developmental timing may play an important role in the behavioral differences between adult wolves and dogs. The purpose of this study is to compare the development of the sensory systems in wolves and dogs. Responses of seven wolf pups and 43 dog pups to familiar and novel olfactory, auditory, and visual stimuli were tested weekly from 2-7 wk of age. Eleven wolf pups were also observed for orientation towards auditory and visual stimuli during 2-h sessions, 5 d a week, from 2-8 wk of age. These observations were supplemented by the daily records of caretakers. The results suggest that wolves and dogs both develop olfaction by 2 wk, audition by 4 wk, and vision by 6 wk on average, despite the 2-wk shift in their ability to explore. This means that when wolves begin to explore at 2 wk, they are blind and deaf, and must rely primarily on their sense of smell. Thus, there is a significant alteration of how these subspecies experience their environment during the critical period of socialization. These findings lead to an alternative explanation for the difference in dogs' and wolves' abilities to form interspecies social attachments, such as those with humans. © 2012 Blackwell Verlag GmbH. Source


Chao W.,University of Massachusetts Amherst
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2016

A 750 GeV resonance has been observed at the run 2 LHC in the diphoton channel. In this paper, we explain this resonance as a CP-even scalar S that triggers the spontaneous breaking of local U(1)B or U(1)B+L gauge symmetries. S couples to gluon and photon pairs at the one-loop level, where particles running in the loop are introduced to cancel anomalies, and the gluon fusion is the dominate production channel of S at the LHC. The model contains a scalar dark matter candidate stabilized by the new gauge symmetry. Our study shows that both the observed production cross section at the LHC and the best fit decay width of S can be explained in this model without conflicting with any other experimental data. Constraints on couplings associated with S are studied, which show that S has a negligible mixing with the standard model Higgs boson but sizable coupling with the dark matter. © 2016 American Physical Society. Source


Umberger B.R.,University of Massachusetts Amherst | Rubenson J.,University of Western Australia
Exercise and Sport Sciences Reviews | Year: 2011

Recent estimates of muscle energy consumption during locomotion, based on computational models and muscle blood flow measurements, demonstrate complex patterns of energy use across the gait cycle, which are further complicated when task demands change. A deeper understanding of muscle energetics in locomotion will benefit from efforts to more tightly integrate muscle-specific approaches with organismal measurements. © 2011 The Amercian College of Sports Medicine. Source


Sievert L.L.,University of Massachusetts Amherst
Menopause | Year: 2014

Although many clinicians are aware of cross-cultural variation in the frequency of hot flash reports at midlife, they may underestimate the extent to which the meaning of menopause, as well as attitudes toward treatment, varies across populations. Likewise, variations in symptom frequency may influence help-seeking behavior. This Practice Pearl offers guidance regarding the issues pertinent to the midlife care of patients from diverse cultures and ethnicities. © 2014 The North American Menopause Society. Source


Chasan-Taber L.,University of Massachusetts Amherst
Best Practice and Research: Clinical Obstetrics and Gynaecology | Year: 2015

While lifestyle interventions involving exercise and a healthy diet in high-risk adults have been found to reduce progression to type 2 diabetes by >50%, little attention has been given to the potential benefits of such strategies in women with a history of gestational diabetes mellitus (GDM). We conducted a literature search of PubMed for English language studies of randomized controlled trials of lifestyle interventions among women with a history of GDM. In total, nine studies were identified which fulfilled the eligibility criteria. The majority of randomized trials of lifestyle interventions in women with GDM have been limited to pilot or feasibility studies. However, preliminary findings suggest that such interventions can improve diabetes risk factors in women with a history of GDM. Larger, well-designed controlled randomized trials are needed to assess the effects of lifestyle interventions on preventing subsequent progression to type 2 diabetes among women with GDM. © 2014 Elsevier Ltd. All rights reserved. Source


Heindel J.J.,National Health Research Institute | Vandenberg L.N.,University of Massachusetts Amherst
Current Opinion in Pediatrics | Year: 2015

Purpose of review Although diseases may appear clinically throughout the lifespan, it is clear that many diseases have origins during development. Altered nutrition, as well as exposure to environmental chemicals, drugs, infections, or stress during specific times of development, can lead to functional changes in tissues, predisposing those tissues to diseases that manifest later in life. This review will focus on the role of altered nutrition and exposures to environmental chemicals during development in the role of disease and dysfunction. Recent findings The effects of altered nutrition or exposure to environmental chemicals during development are likely because of altered programming of epigenetic marks, which persist across the lifespan. Indeed some changes can be transmitted to future generations. Summary The evidence in support of the developmental origins of the health and disease paradigm is sufficiently robust and repeatable across species, including humans, to suggest a need for greater emphasis in the clinical area. As a result of these data, obesity, diabetes, cardiovascular morbidity, and neuropsychiatric diseases can all be considered pediatric diseases. Disease prevention must start with improved nutrition and reduced exposure to environmental chemicals during development. © 2015 Wolters Kluwer Health, Inc. Source


Ovanesyan G.,University of Massachusetts Amherst | Slatyer T.R.,Massachusetts Institute of Technology | Stewart I.W.,Massachusetts Institute of Technology
Physical Review Letters | Year: 2015

We formulate an effective field theory description for SU(2)L triplet fermionic dark matter by combining nonrelativistic dark matter with gauge bosons in the soft-collinear effective theory. For a given dark matter mass, the annihilation cross section to line photons is obtained with 5% precision by simultaneously including Sommerfeld enhancement and the resummation of electroweak Sudakov logarithms at next-to-leading logarithmic order. Using these results, we present more accurate and precise predictions for the gamma-ray line signal from annihilation, updating both existing constraints and the reach of future experiments. © 2015 American Physical Society. Source


Forbes N.S.,University of Massachusetts Amherst
Nature Reviews Cancer | Year: 2010

Bacterial therapies possess many unique mechanisms for treating cancer that are unachievable with standard methods. Bacteria can specifically target tumours, actively penetrate tissue, are easily detected and can controllably induce cytotoxicity. Over the past decade, Salmonella, Clostridium and other genera have been shown to control tumour growth and promote survival in animal models. In this Innovation article I propose that synthetic biology techniques can be used to solve many of the key challenges that are associated with bacterial therapies, such as toxicity, stability and efficiency, and can be used to tune their beneficial features, allowing the engineering of 'perfect' cancer therapies. © 2010 Macmillan Publishers Limited. All rights reserved. Source


McClements D.J.,University of Massachusetts Amherst
Therapeutic Delivery | Year: 2013

Nanoemulsions have considerable potential for encapsulating, protecting and delivering lipophilic bioactive components via the oral route, such as pharmaceuticals (drugs) and nutraceuticals (food components with specific health benefits). These systems can be fabricated from generally recognized as safe ingredients using relatively simple processing operations, such as mixing and homogenization. Some of the potential advantages of nanoemulsions over conventional emulsions include higher bioaccessibility, higher physical stability and higher optical clarity. An overview of the current status of nanoemulsion fabrication, stability, properties and biological fate is given, with special emphasis on the suitability of nanoemulsions for the oral delivery of hydrophobic bioactive components, such as drugs and nutraceuticals. © 2013 Future Science Ltd. Source


Ryan R.L.,University of Massachusetts Amherst
Landscape and Urban Planning | Year: 2011

During the past decades, there have been tremendous strides in the sophistication and power of analyzing, displaying, and interpreting spatial information, particularly Geographic Information Systems (GIS). The vast majority of this work has focused on the physical landscape where increasingly complex models are able to predict, describe, and assess the implications of future planning issues related to watersheds, urban growth, and other planning issues. However, this increasing sophistication in the power of landscape modeling remains disconnected from the sociopolitical realities of the communities and regions which are the subject of these studies. There is a research need to integrate public perceptions and attitudes with the type of information typically found in a landscape assessment. This essay reviews the different types of social and perceptual research that landscape planners have conducted and concludes with recommendations for research avenues that are necessary to describe the social landscape in spatial terms. Landscape planners in the future will need to know as much about the social landscape as they do the physical landscape before embarking on planning actions. © 2011 Elsevier B.V. Source


Markstein M.,University of Massachusetts Amherst
Drug Discovery Today: Technologies | Year: 2013

This review discusses recent shifts in the understanding of colorectal cancer as a stem cell based disease, based on findings that tie patient prognosis to the presence of cancer stem cells in colorectal tumors. Currently no drugs specifically target CSCs in colorectal tumors. However, recent advances in the culturing of colorectal stem cells using mammalian organoids, zebrafish, and Drosophila offer promising avenues for anti-CSC drug discovery. © 2012 Elsevier Ltd. All rights reserved. Source


Peleg M.,University of Massachusetts Amherst
Applied and environmental microbiology | Year: 2013

Isothermal germination curves, sigmoid and nonsigmoid, can be described by a variety of models reminiscent of growth models. Two of these, which are consistent with the percent of germinated spores being initially zero, were selected: one, Weibullian (or "stretched exponential"), for more or less symmetric curves, and the other, introduced by Dantigny's group, for asymmetric curves (P. Dantigny, S. P.-M. Nanguy, D. Judet-Correia, and M. Bensoussan, Int. J. Food Microbiol. 146:176-181, 2011). These static models were converted into differential rate models to simulate dynamic germination patterns, which passed a test for consistency. In principle, these and similar models, if validated experimentally, could be used to predict dynamic germination from isothermal data. The procedures to generate both isothermal and dynamic germination curves have been automated and posted as freeware on the Internet in the form of interactive Wolfram demonstrations. A fully stochastic model of individual and small groups of spores, developed in parallel, shows that when the germination probability is constant from the start, the germination curve is nonsigmoid. It becomes sigmoid if the probability monotonically rises from zero. If the probability rate function rises and then falls, the germination reaches an asymptotic level determined by the peak's location and height. As the number of individual spores rises, the germination curve of their assemblies becomes smoother. It also becomes more deterministic and can be described by the empirical phenomenological models. Source


Holstein B.R.,University of Massachusetts Amherst
Journal of Physics G: Nuclear and Particle Physics | Year: 2014

Recent advances in experimental physics have opened a new frontier for the precision measurements in low energy weak interactions. In this note we discuss the theoretical basis for the analysis of such experiments and their implications for the standard model. © 2014 IOP Publishing Ltd. Source


Ueki T.,University of Massachusetts Amherst
Applied and Environmental Microbiology | Year: 2011

Subsurface environments contaminated with aromatic compounds can be remediated in situ by Geobacter species. A transcription factor that represses expression of bamA, a benzoate-inducible gene, in Geobacter bemidjiensis during growth with acetate was identified. It is likely that this repressor also regulates other genes involved in aromatic compound metabolism. © 2011, American Society for Microbiology. Source


Chao W.,University of Massachusetts Amherst
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2016

The ATLAS Collaboration has reported excesses in diboson invariant mass searches of new resonances around 2 TeV, which might be a prediction of new physics around that mass range. We interpret these results in the context of a modified stealth doublet model where the extra Higgs doublet has a Yukawa interaction with the first generation quarks, and show that the heavy CP-even Higgs boson can naturally explain the excesses in the WW and ZZ channels with a small Yukawa coupling, ξ ~ 0.15, and a tiny mixing angle with the SM Higgs boson, α ~ 0.05. Furthermore, the model satisfies constraints from colliders and electroweak precision measurements. © 2015 The Author. Source


The twenty-first century global population will be increasingly urban-focusing the sustainability challenge on cities and raising new challenges to address urban resilience capacity. Landscape ecologists are poised to contribute to this challenge in a transdisciplinary mode in which science and research are integrated with planning policies and design applications. Five strategies to build resilience capacity and transdisciplinary collaboration are proposed: biodiversity; urban ecological networks and connectivity; multifunctionality; redundancy and modularization, adaptive design. Key research questions for landscape ecologists, planners and designers are posed to advance the development of knowledge in an adaptive mode. © 2012 Springer Science+Business Media B.V. Source


Pace-Schott E.F.,Harvard University | Spencer R.M.C.,University of Massachusetts Amherst
Current Topics in Behavioral Neurosciences | Year: 2015

Sleep quality and architecture as well as sleep’s homeostatic and circadiancontrols change with healthy aging. Changes include reductions in slow-wavesleep’s (SWS) percent and spectral power in the sleep electroencephalogram (EEG),number and amplitude of sleep spindles, rapid eye movement (REM) density and theamplitude of circadian rhythms, as well as a phase advance (moved earlier in time)of the brain’s circadian clock. With mild cognitive impairment (MCI) there arefurther reductions of sleep quality, SWS, spindles, and percent REM, all of whichfurther diminish, along with a profound disruption of circadian rhythmicity, with theconversion to Alzheimer’s disease (AD). Sleep disorders may represent risk factorsfor dementias (e.g., REM Behavior Disorder presages Parkinson’s disease) andsleep disorders are themselves extremely prevalent in neurodegenerative diseases.Working memory, formation of new episodic memories, and processing speed alldecline with healthy aging whereas semantic, recognition, and emotional declarativememory are spared. In MCI, episodic and working memory further declinealong with declines in semantic memory. In young adults, sleep-dependent memoryconsolidation (SDC) is widely observed for both declarative and proceduralmemory tasks. However, with healthy aging, although SDC for declarative memoryis preserved, certain procedural tasks, such as motor-sequence learning, do not showSDC. In younger adults, fragmentation of sleep can reduce SDC, and a normative ©Springer-Verlag Berlin Heidelberg 2014. Source


Blaustein J.D.,University of Massachusetts Amherst
Hormone and Metabolic Research | Year: 2012

Many of the influences of estrogens and progestins on the brain and behavior are mediated by estrogen receptors and progestin receptors, acting as transcriptional regulators. The homologous and heterologous regulation of the concentrations of these receptors by cognate hormones is well established. However, although they were discovered and characterized based on their binding to cognate hormone and their role in transcriptional regulation, steroid hormone receptors have a more complex role and serve many more functions than originally suspected. First, besides being regulated by steroid hormones, the intracellular concentrations of brain steroid hormone receptors are regulated by neurotransmitters, a pathway by which stimuli from the environment, including from conspecific animals, can modulate the concentration of particular steroid hormone receptors in subsets of cells. Further, besides being activated by cognate steroid hormones, the receptors can be activated by a variety of neurotransmitters and phosphorylation pathways, providing a route through which environmental stimulation can activate steroid-receptor-dependent functions in specific cells. In addition, the transcription factor, estrogen receptor-α, produced from the estrogen receptor-α gene, can be modified to be targeted to membranes, where it can signal via kinase pathways. Finally, developmental experiences, such as particular stressors during the pubertal period, can permanently remodel the brain's response to ovarian hormones, most likely by long-term changes in regulation of the receptors mediating those responses. In addition to their function in responding to cognate ligand, it is now more appropriate to think of steroid hormone receptors as integrators of a wide variety of signaling pathways. © Georg Thieme Verlag KG Stuttgart. New York. Source


Wang W.,University of Massachusetts Amherst
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2015

An efficient and simple approach of measuring the absolute free energy as a function of temperature for spin lattice models using a two-stage parallel tempering Monte Carlo and the free energy perturbation method is discussed and the results are compared with those of population annealing Monte Carlo using the three-dimensional Edwards-Anderson Ising spin glass model as benchmark tests. This approach requires little modification of regular parallel tempering Monte Carlo codes with also little overhead. Numerical results show that parallel tempering, even though using a much less number of temperatures than population annealing, can nevertheless equally efficiently measure the absolute free energy by simulating each temperature for longer times. © 2015 American Physical Society. Source


Calabrese E.J.,University of Massachusetts Amherst | Mattson M.P.,National Institute of Aging Intramural Research Program
Journal of Cell Communication and Signaling | Year: 2011

Phenotypic plasticity represents an environmentally-based change in an organism's observable properties. Since biological plasticity is a fundamental adaptive feature, it has been extensively assessed with respect to its quantitative features and genetic foundations, especially within an ecological evolutionary framework. Toxicological investigations on the dose-response continuum (i.e., very broad dose range) that include documented evidence of the hormetic dose response zone (i.e., responses to doses below the toxicological threshold) can be employed to provide a quantitative estimate of phenotypic plasticity. The low dose hormetic stimulation is an adaptive response that reflects an environmentally-induced altered phenotype and provides a quantitative estimate of biological plasticity. Analysis of nearly 8,000 dose responses within the hormesis database indicates that quantitative features of phenotypic plasticity are highly generalizable, being independent of biological model, endpoint measured and chemical/physical stress inducing agent. The magnitude of phenotype changes indicative of plasticity is modest with maximum responses typically being approximately 30-60% greater than control values. The present findings provide the first quantitative estimates of biological plasticity and its capacity for generalization. Summary This article provides the first quantitative estimate of biological plasticity that may be generalized across plant, microbial, animal systems, and across all levels of biological organization. The quantitative features of plasticity are described by the hormesis dose response model. These findings have important biological, biomedical and evolutionary implications. © 2011 US Government. Source


Fathi M.,Isfahan University of Technology | Martin T.,University of Valladolid | McClements D.J.,University of Massachusetts Amherst
Trends in Food Science and Technology | Year: 2014

Natural and modified polysaccharides are promising vehicles for nano- and micro-encapsulation of active food ingredients. This article reviews the state of the art of carbohydrate-based delivery systems for utilization in the food, pharmaceutical and other industries. Initially, an overview of the different kinds of carbohydrates used to assemble delivery systems is given, including starch, cellulose, pectin, guar gum, chitosan, alginate, dextrin, cyclodextrins, new sources of native gums, and their combinations and chemically modified forms. Their molecular and physicochemical properties, functional performance, and advantages and disadvantages for encapsulation are given. Various approaches for fabrication of carbohydrate-based delivery systems are then discussed, including coacervation, spray drying, electrospinning, electrospray, supercritical fluid, emulsion-diffusion, reverse micelle, emulsion-droplet coalescence, emulsification/solvent evaporation, salting-out, ultrasonication and high pressure homogenization. The biological fate of carbohydrate nanocarriers during digestion, absorption, metabolism and excretion are discussed, and some notes about their bioavailability and potential toxicity are provided. Finally, the functional performances of different carbohydrate-based delivery systems are discussed, and future developments are highlighted. © 2014 Elsevier Ltd. Source


Pozrikidis C.,University of Massachusetts Amherst
European Journal of Mechanics, B/Fluids | Year: 2015

Flow through a twisted tube with square cross-section and helical corrugations of arbitrary pitch is computed under conditions of Stokes flow. The governing equations are formulated in non-orthogonal helical coordinates in terms of a coupled system of linear differential equations describing the longitudinal and transverse flow over the tube cross-section. Numerical solutions are computed by a finite-difference method on a staggered grid incorporating pressure nodes and three sets of velocity nodes. The results illustrate the structure of the secondary flow developing over the tube cross-section and document the effect of the helical corrugations on the axial flow rate. © 2014 Elsevier Masson SAS. All rights reserved. Source


Rounds C.M.,Mount Holyoke College | Bezanilla M.,University of Massachusetts Amherst
Annual Review of Plant Biology | Year: 2013

Tip growth is employed throughout the plant kingdom. Our understanding of tip growth has benefited from modern tools in molecular genetics, which have enabled the functional characterization of proteins mediating tip growth. Here we first discuss the evolutionary role of tip growth in land plants and then describe the prominent model tip-growth systems, elaborating on some advantages and disadvantages of each. Next we review the organization of tip-growing cells, the role of the cytoskeleton, and recent developments concerning the physiological basis of tip growth. Finally, we review advances in the understanding of the extracellular signals that are known to guide tip-growing cells. © Copyright ©2013 by Annual Reviews. All rights reserved. Source


Brooks R.T.,University of Massachusetts Amherst
Biodiversity and Conservation | Year: 2011

White-nose syndrome (WNS) was first reported in a hibernating bat population in central New York State in February 2006. Since 2006, WNS has been reported from bat hibernacula across much of eastern United States and adjacent Canada and has been associated with a dramatic decline in the populations of hibernating bats in the northeastern U. S. We are only beginning to discover how these declines are manifest in changes in summer bat abundance and activity at local scales. A 3-year (2004-2006) acoustic survey showed that the forested watershed of the Quabbin Reservoir in central Massachusetts supported an abundant and species-rich summer bat community. In 2010, 4-years following the initial occurrence of WNS, a re-survey of the same habitats and sites found a 72% reduction in bat activity on the watershed. This is the identical rate of decline reported from cave hibernacula surveys (73%). This decline in summer activity levels is most likely a consequence of WNS-caused mortality. The impacts of population losses of this magnitude of a once widespread and abundant taxa are unknown but are presumed to be ecologically significant. © 2011 Springer Science+Business Media B.V. (outside the USA). Source


Perot J.B.,University of Massachusetts Amherst
Annual Review of Fluid Mechanics | Year: 2011

Numerical methods with discrete conservation statements are useful because they cannot produce solutions that violate important physical constraints. A large number of numerical methods used in computational fluid dynamics (CFD) have either global or local conservation statements for some of the primary unknowns of the method. This review suggests that local conservation of primary unknowns often follows from global conservation of those quantities. Secondary conservation involves the conservation of derived quantities, such as kinetic energy, entropy, and vorticity, which are not directly unknowns of the numerical system. Secondary conservation can further improve physical fidelity of a numerical solution, but it is typically much harder to achieve. We consider current approaches to secondary conservation and techniques used outside of CFD that are potentially related. Finally, the review concludes with a discussion of how secondary conservation properties might be included automatically. © 2011 by Annual Reviews. All rights reserved. Source


Sorbo L.,University of Massachusetts Amherst
Journal of Cosmology and Astroparticle Physics | Year: 2011

If the inflaton φ is a pseudoscalar, then it naturally interacts with gauge fields through the coupling φFμν μν. Through this coupling, the rolling inflaton produces quanta of the gauge field, that in their turn source the tensor components of the metric perturbations. Due to the parity-violating nature of the system, the right- and the left-handed tensor modes have different amplitudes. Such an asymmetry manifests itself in the form of non-vanishing TB and EB correlation functions in the Cosmic Microwave Background (CMB). We compute the amplitude of the parity-violating tensor modes and we discuss two scenarios, consistent with the current data, where parity-violating CMB correlation functions will be detectable in future experiments. © 2011 IOP Publishing Ltd and SISSA. Source


Kim H.-D.,Massachusetts Institute of Technology | Peyton S.R.,University of Massachusetts Amherst
Integrative Biology | Year: 2012

Cell motility is ubiquitous in both normal and pathophysiological processes. It is a complex biophysical response elicited via the integration of diverse extracellular physicochemical cues. The extracellular matrix directs cell motility via gradients in morphogens (a.k.a. chemotaxis), adhesive proteins (haptotaxis), and stiffness (durotaxis). Three-dimensional geometrical and proteolytic cues also constitute key regulators of motility. Therefore, cells process a variety of physicochemical signals simultaneously, while making informed decisions about migration via intracellular processing. Over the last few decades, bioengineers have created and refined natural and synthetic in vitro platforms in an attempt to isolate these extracellular cues and tease out how cells are able to translate this complex array of dynamic biochemical and biophysical features into functional motility. Here, we review how biomaterials have played a key role in the development of these types of model systems, and how recent advances in engineered materials have significantly contributed to our current understanding of the mechanisms of cell migration. © 2011 The Royal Society of Chemistry. Source


Stefanov A.,University of Kansas | Kevrekidis P.,University of Massachusetts Amherst
Nonlinearity | Year: 2013

In the present work, we complement our earlier study on the subject of granular crystals in the purely nonlinear limit (no precompression) by considering the case where an underlying linear limit exists (finite precompression). In the latter context, we explicitly prove the existence of supersonic travelling waves, which are smooth, positive and exponentially localized. While numerical computations suggest that the cutoff point for the existence of such exponentially decaying waves is exactly the speed of sound in the system, we can not establish this result sharply within our variational technique but can only prove a relevant upper bound on the propagation speed of bell-shaped travelling waves in the strain variables. © 2013 IOP Publishing Ltd & London Mathematical Society. Source


Turkington B.,University of Massachusetts Amherst
Journal of Statistical Physics | Year: 2013

A general method for deriving closed reduced models of Hamiltonian dynamical systems is developed using techniques from optimization and statistical estimation. Given a vector of resolved variables, selected to describe the macroscopic state of the system, a family of quasi-equilibrium probability densities on phase space corresponding to the resolved variables is employed as a statistical model, and the evolution of the mean resolved vector is estimated by optimizing over paths of these densities. Specifically, a cost function is constructed to quantify the lack-of-fit to the microscopic dynamics of any feasible path of densities from the statistical model; it is an ensemble-averaged, weighted, squared-norm of the residual that results from submitting the path of densities to the Liouville equation. The path that minimizes the time integral of the cost function determines the best-fit evolution of the mean resolved vector. The closed reduced equations satisfied by the optimal path are derived by Hamilton-Jacobi theory. When expressed in terms of the macroscopic variables, these equations have the generic structure of governing equations for nonequilibrium thermodynamics. In particular, the value function for the optimization principle coincides with the dissipation potential that defines the relation between thermodynamic forces and fluxes. The adjustable closure parameters in the best-fit reduced equations depend explicitly on the arbitrary weights that enter into the lack-of-fit cost function. Two particular model reductions are outlined to illustrate the general method. In each example the set of weights in the optimization principle contracts into a single effective closure parameter. © 2013 Springer Science+Business Media New York. Source


Morse S.A.,University of Massachusetts Amherst
American Mineralogist | Year: 2011

The fractional latent heat of a crystallizing system is simply the latent heat of fusion divided by the total enthalpy. When plotted against temperature, this function displays robust pulses with the successive saturation of each incoming crystal phase. Each pulse endures for tens of degrees, corresponding to tens to hundreds of thousands of years in large magma bodies. From an original 1963 development by P. J. Wyllie using a synthetic system, I show that the liquidus slopes (degrees per gram of solid produced) decrease discontinuously at the arrival of a new phase, and their inverse, the crystal productivity, undergoes sharp upward pulses at the same time. The overall liquidus slope increases continuously, interrupted by small downward jumps, with the evolution of the multicomponent melt. The crystal productivity pulses feed the fractional latent heat pulses, which dominate the crystallization history of a melt. These elementary relationships govern the near-solidus growth of dihedral angles in cumulates as they relate to the liquidus events. The latent heat ordinarily approximates to about 80% of the total enthalpy budget, but jumps to 100% (by definition) when solidification occurs by isothermal adcumulus growth and approaches 100% when mafic phases such as augite and Fe-Ti oxides are over-produced (relative to their equilibrium saturation) in layered intrusions. The feedback of latent heat to a self-regulating cooling history of large magma bodies is deduced here in principle. The overall results help to clarify the crystallization history of mafic magmas. In particular, they support the solidification of floor cumulates by interchange with parent magma and without the help of compaction. Source


Kwon D.-H.,University of Massachusetts Amherst
IEEE Transactions on Antennas and Propagation | Year: 2015

For infinite planar phased array elements, a vector effective height is determined and the receiving area and receiving efficiency are found in terms of transmitting performance descriptors. The vector effective height allows the open-circuit received voltage to be expressed as an inner product with the incident electric field, as is for an isolated antenna. Generalizing a previously known expression, the effective area is expressed in terms of polarization mismatch, radiation efficiency, impedance mismatch, and the projected unit cell area, together with the element Floquet directivity introduced in this study that quantifies the unidirectional or bidirectional nature of radiation. An element's total receiving efficiency is defined and its expression is inspected for maximizing the received power. © 1963-2012 IEEE. Source


Bushouse B.K.,University of Massachusetts Amherst
Policy Studies Journal | Year: 2011

Club goods with information asymmetry are frequently provided through mixed economies of for-profit, nonprofit, and public providers. Theory explaining mixed economies relies on sector to classify providers based on assumptions that sector-level differences in how organizations either distribute or reinvest profit will affect behavior. However, this classification is overly broad and is not able to adequately capture the diversity of providers of these types of goods. The author utilizes the Institutional Analysis and Development framework to identify six "governance structures" in the for-profit and nonprofit sectors. Governance structures are constitutional-choice level rule variations in who has the power to make rules. I argue that there are two types of power that affect rules: (1) concentration of constitutional-choice level decision-making power (i.e., how many principals) and (2) proximity of monitoring and enforcement of those rules. The extent to which the constitutional rules actually guide service delivery outcomes depends on a nested rule environment. Only if there is consistency across three level of rules (constitutional, collective, and operational) can we connect sector to outcomes. The empirical reality of service delivery, particularly for club goods with information asymmetry, is far too complex for simplistic assumptions linking profit distribution or its reinvestment to outcomes. This article directs further research toward building contingent theory, with if/then conditions, based on empirical research. © 2011 Policy Studies Organization. Source


Moseley D.L.,University of Massachusetts Amherst
Proceedings. Biological sciences / The Royal Society | Year: 2013

Mating signals of many animal species are difficult to produce and thus should indicate signaler quality. Growing evidence suggests that receivers modulate their behaviour in response to signals with varying performance levels, although little is known about if and how responses are affected by receiver attributes. To explore this topic we conducted two experiments with swamp sparrows, Melospiza georgiana, in which we challenged territorial males with playback of songs with trill rates that were natural, digitally reduced, or digitally elevated (control-, low- and high-performance stimuli, respectively). In our first experiment, we found that males responded more aggressively to control songs than to low-performance stimuli, that low-performance stimuli with the most severe trill-rate reductions elicited the weakest aggressive responses, and that the subjects' own trill rates predicted aggressive responses. In our second experiment, we found that male responses to high-performance stimuli varied significantly, in ways predicted by two factors: the degree to which we had elevated stimulus performance levels of high-performance stimuli, and subjects' own vocal performance levels. Specifically, males were less aggressive towards stimuli for which we had elevated performance levels to higher degrees, and subject males with higher vocal performances themselves responded more aggressively. These findings together offer a novel illustration of how responses to aggressive signals may rely not just on signal attributes, but also on attributes of responding animals themselves. Source


Calabrese E.J.,University of Massachusetts Amherst
Homeopathy | Year: 2015

The present paper provides an historical assessment of the concept of hormesis and its relationship to homeopathy and modern medicine. It is argued that the dose-response concept was profoundly influenced by the conflict between homeopathy and traditional medicine and that decisions on which dose-response model to adopt were not based on "science" but rater on historical antipathies. While the historical dispute between homeopathy and traditional medicine has long since subsided, their impact upon the field has been enduring and generally unappreciated, profoundly adversely affecting current drug development, therapeutic strategies and environmental risk assessment strategies and policies. © 2015 The Faculty of Homeopathy. Source


Li G.-L.,Oregon Health And Science University | Li G.-L.,University of Massachusetts Amherst | Cho S.,Oregon Health And Science University | von Gersdorff H.,Oregon Health And Science University
Neuron | Year: 2014

Sound-evoked spikes in the auditory nerve can phase-lock with submillisecond precision for prolonged periods of time. However, the synaptic mechanisms that enable this accurate spike firing remain poorly understood. Using paired recordings from adult frog hair cells and their afferent fibers, we show here that during sine-wave stimuli, synaptic failures occur even during strong stimuli. However, exclusion of these failures leads to mean excitatory postsynaptic current (EPSC) amplitudes that are independent of Ca2+ current. Given the intrinsic jitter in spike triggering, evoked synaptic potentials and spikes had surprisingly similar degrees of synchronization to a sine-wave stimulus. This similarity was explained by an unexpected finding: large-amplitude evoked EPSCs have a significantly larger synchronization index than smaller evoked EPSCs. Large EPSCs therefore enhance the precision of spike timing. The hair cells' unique capacity for continuous, large-amplitude, and highly synchronous multiquantal release thus underlies its ability to trigger phaselocked spikes in afferent fibers. © 2014 Elsevier Inc. Source


Wolf T.,University of Massachusetts Amherst
IEEE Network | Year: 2010

The design of the current Internet lacks in adaptability to accommodate novel network uses and functional requirements. It is therefore important to explore how new services can be introduced into the network infrastructure. We present a novel network architecture that can accommodate the deployment and custom instantiation of such network services. We discuss the motivation for our design and several of the research challenges that arise in this context. © 2010 IEEE. Source


Grason G.M.,University of Massachusetts Amherst
Reviews of Modern Physics | Year: 2015

This Colloquium presents recent progress in understanding constraints and consequences of close-packing geometry of filamentous or columnar materials possessing nontrivial textures, focusing, in particular, on the common motifs of twisted and toroidal structures. The mathematical framework is presented that relates spacing between linelike, filamentous elements to their backbone orientations, highlighting the explicit connection between the interfilament metric properties and the geometry of non-Euclidean surfaces. The consequences of the hidden connection between packing in twisted filament bundles and packing on positively curved surfaces, like the Thomson problem, are demonstrated for the defect-riddled ground states of physical models of twisted filament bundles. The connection between the "ideal" geometry of fibrations of curved three-dimensional space, including the Hopf fibration, and the non-Euclidean constraints of filament packing in twisted and toroidal bundles is presented, with a focus on the broader dependence of metric geometry on the simultaneous twisting and folding of multifilament bundles. © 2015 American Physical Society. Source


Clerico E.M.,University of Massachusetts Amherst
Biopolymers | Year: 2010

Introducing biophysical labels into specific regions of large and dynamic multidomain proteins greatly facilitates mechanistic analysis. Ligation of expressed domains that are labeled in a desired manner before assembly of the intact molecular machine provides such a strategy. We have elaborated an experimental route using expressed protein ligation (EPL) to create an Hsp70 molecular chaperone (the E. coli Hsp70, DnaK) where only one of the two constituent domains was labeled, in this case with NMR active isotopes, allowing visualization of the single domain in the context of the two domain protein. Several technical obstacles were overcome, including choice of site for ligation with retention of function, optimization of ligation yield, and purification from unreacted domains. Ligated semilabeled DnaK was successfully produced with a Cys residue at position 383, and the ligated product harboring the Cys mutation was confirmed to be functional and identical to an expressed Cys-containing two-domain construct. The NMR spectrum of the segmentally labeled protein was considerably simplified, enabling unequivocal assignment and enhanced analysis of dynamics, as a prelude to exploring the energy landscape for allostery in the Hsp70 family. 2010 Wiley Periodicals, Inc. Source


Wakai T.,Tokyo University of Agriculture | Fissore R.A.,University of Massachusetts Amherst
Cell Calcium | Year: 2013

The activation of the developmental program in mammalian eggs relies on the initiation at the time of fertilization of repeated rises in the intracellular concentration of free calcium ([Ca2+]i), also known as [Ca2+]i oscillations. The ability to mount the full complement of oscillations is only achieved at the end of oocyte maturation, at the metaphase stage of meiosis II (MII). Over the last decades research has focused on addressing the mechanisms by which the sperm initiates the oscillations and identification of the channels that mediate intracellular Ca2+ release. This review will describe the up-to-date knowledge of other aspects of Ca2+ homeostasis in mouse oocytes, such as the mechanisms that transport Ca2+ out of the cytosol into the endoplasmic reticulum (ER), the Ca2+ store of the oocyte/egg, into other organelles and also those that extrude Ca2+. Evidence pointing to channels in the plasma membrane that mediate Ca2+ entry from the extracellular milieu, which is required for the persistence of the oscillations, is also discussed, along with the modifications that these mechanisms undergo during maturation. Lastly, we highlight areas where additional research is needed to obtain a better understating of the molecules and mechanisms that regulate Ca2+ homeostasis in this unique Ca2+ signaling system. © 2012 Elsevier Ltd. Source