bluuebunny/crossref_metadata_2025 huggingface dataset:
Cancer‐related fatigue: the impact of skeletal muscle mass and strength in patients with advanced cancer
Authors: Kilgour Robert D. , Vigano Antonio , Trutschnigg Barbara , Hornby Laura , Lucar Enriqueta , Bacon Simon L. , Morais José A.
Published: December 2010

Background

Although exertional fatigue is directly and negatively related to skeletal muscle mass and strength, it is currently unknown if these variables are associated with cancer‐related fatigue (CRF). Therefore, the purpose of this study was to determine if CRF is associated with measures of appendicular lean muscle mass and strength in advanced cancer patients (ACP).

Methods and results

Eighty‐four patients (48 men, 36 women aged 61.6 ± 13.2 year) newly diagnosed (≤6 months) with inoperable (Stages III–IV) gastrointestinal or non‐small cell lung cancer participated in this study. All patients completed the Brief Fatigue Inventory (BFI). Handgrip (HGS) and quadriceps (QS) strength were assessed using isometric and isokinetic dynamometry, respectively. Skeletal muscle mass index (SMMI) was calculated from the appendicular lean mass measured via dual‐energy X‐ray absorptiometry divided by body height squared. Univariate analysis showed BFI to be significantly associated with body mass index, weight loss, anemia, hypoalbuminemia, activity level, pain, depression, and sarcopenia along with SMMI, HGS, and QS. HGS (r = −0.34; p = 0.018), QS (r = −0.39; p = 0.024), and SMMI (r = −0.60; p < 0.001) were negatively correlated with BFI total scores in men but not in women. When adjusted for sex, age, diagnosis, survival, along with the above characteristics, multivariate analyses showed that BFI scores were negatively associated with HGS (B = −0.90; 95% CI −1.5:−0.3), QS (−0.2; −0.3:−0.01), and SMMI (−7.5; −13.0:−2.0). There was a significant sex × SMMI interaction (10.8; 1.2:20.5), where BFI decreased with increasing SMMI in men, but did not change with SMMI in women.

Conclusion

These results suggest that in ACP, CRF is related to muscle mass and strength, which may provide targets for future interventions.
Agreement between parent‐ and self‐reports of Algerian adolescents’ behavioral and emotional problems
Authors: Petot Djaouida , Rescorla Leslie , Petot Jean‐Michel
Published: December 2010

The present study examined agreement between scores obtained from self‐reports of behavioral and emotional problems obtained from 513 Algerian adolescents on the Youth Self‐Report (YSR) with scores obtained from reports provided by their parents on the Child Behavior Checklist (CBCL). The correlations between self‐ and parent‐report were larger than those observed in many other cultures (e.g., intraclass correlation coefficient = 0.60 and Pearson r = 0.65 for Total Problems). On the whole, cross‐informant agreement did not vary significantly as a function of problem type, identity of the parental informant, gender and age of the adolescent. Similar to all studied cultures, adolescents on average reported more problems than their parents reported about them, but the discrepancies were smaller than in all previous societies. Mean YSR/CBCL score discrepancies indicated higher YSR scores for several scales, but variability across dyads was large, and many dyads showed the opposite pattern.
Risk factors of sciatic pain: A prospective study among middle—aged employees
Authors: Kääriäl Sanna , Leino‐Arjasl Päivi , Rahkonenl Ossi , Lahtil Jouni , Lahelmal Eero , Laaksonenl Mikko
Published: December 2010

Objective: To study the effects of occupational class, physical and psychosocial working conditions, health behaviours, and pain in the low back and the neck on sciatic pain among middle‐aged employees.

Methods: The participants were municipal employees without previous sciatica, aged 40, 45, 50, 55, and 60 years at baseline (n =5261, 80% women). Sciatica was defined as low back pain radiating to the calf or the foot. Data on occupational class, physical and psychosocial working conditions, body mass index, smoking, leisure‐time physical activity, neck pain, local low back pain, and sciatica were obtained from baseline questionnaire surveys in 2000–2002. The question on sciatica was repeated in a follow‐up survey in 2007. Logistic regression analysis was used.

Results: In women, manual occupational class (OR 1.3; 95% CI 1.0–1.6 compared with managers/professionals), overweight (1.3; 1.1–1.5), obesity (1.4; 1.1–1.7), smoking (1.5; 1.2–1.7), low leisure‐time physical activity (1.3; 1.0–1.7), previous acute (1.5; 1.3–1.7) and chronic (1.5; 1.1–2.0) local low back pain, and acute (1.20; 1.0–1.4) and chronic (1.5;1.2–1.9) neck pain predicted the onset of sciatica in a multivariable model. In men, semi‐professionals (1.5; 1.1–2.1) and manual workers (2.0; 1.4–2.8) had an increased risk compared with managers/professionals; also acute (1.5; 1.2–2.0) and chronic (2.1; 1.2–3.9) local low back pain predicted sciatica.

Conclusions: Manual occupational class in both genders and semi‐professional occupations in men, unhealthy behaviours and previous pain both in the neck and the lower back predicted sciatica, while physical and psychosocial working conditions had no independent effect.
Relative role of decreasing precipitation sulfate and climate on recent lake recovery
Authors: Houle Daniel , Couture Suzanne , Gagnon Christian
Published: December 2010

In the last 2 decades, acidic sulfur (S) depositions and SO4 concentration in surface water significantly decreased in many regions of the world, while at the same time temperatures have been increasing, particularly in the decade 1995–2005, which was one of the warmest ever recorded in the Northern Hemisphere. Understanding the potentially antagonistic or additive effects of decreasing S depositions and increasing temperatures on lake chemistry is essential to adequately evaluate the effectiveness of reduction programs for S emissions. By assessing the rate of change in climate variables, precipitation SO4 and lake chemistry for 47 temperate and boreal catchments, we found that changes in climate, particularly higher annual temperatures, were more often correlated to lake's pH and alkalinity than was the rate of decreasing S depositions between 1989 and 2005. It suggests that the recent improvement in the acid‐base status of the studied lakes that cover a large area of northeastern North America as well as a large array of acid‐base conditions cannot be attributed solely to a decrease in SO4 precipitation, but also to climatic variations. Not taking this information into account could lead to an overestimation of the benefit of lower SO4 deposition on aquatic ecosystems recovery.
Lattice‐Boltzmann modeling of the air permeability of polar firn
Authors: Courville Zoe , Hörhold Maria , Hopkins Mark , Albert Mary
Published: December 2010

Recent advances in three‐dimensional (3D) imaging of snow and firn combined with numerical modeling of flow through complex geometries have greatly improved the ability to predict permeability values based on microstructure. In this work, we combined 3D reconstructions of polar firn microstructure obtained from microcomputed tomography (μCT) and a 3D lattice‐Boltzmann (LB) model of air flow. We compared the modeled results to measurements of permeability for polar firn with a wide range of grain and pore‐scale characteristics. The results show good agreement between permeability measurements and calculated permeability values from the LB model over a wide range of sample types. The LB model is better at predicting measured permeability values than traditional empirical equations for polar firn.
Measuring willingness to pay to improve municipal water in southeast Anatolia, Turkey
Authors: Bilgic Abdulbaki
Published: December 2010

Increasing demands for water and quality concerns have highlighted the importance of accounting for household perceptions before local municipalities rehabilitate existing water infrastructures and bring them into compliance. We compared different willingness‐to‐pay (WTP) estimates using household surveys in the southern Anatolian region of Turkey. Our study is the first of its kind in Turkey. Biases resulting from sample selection and the endogeneity of explanatory variables were corrected. When compared to a univariate probit model, correction of these biases was shown to result in statistically significant findings through moderate reductions in mean WTP.
Deepening of the nutricline and chlorophyll maximum in the Canada Basin interior, 2003–2009
Authors: McLaughlin Fiona A. , Carmack Eddy C.
Published: December 2010

Physical and chemical data collected in the Canada Basin interior from 2003–2009 show that recent increases in both Ekman convergence and freshwater input, associated with sea ice retreat and melt, have affected the structure and dynamics of the upper ocean, and such changes accelerated from 2007–2009 when salt‐stratification below the seasonal mixed layer increased about 25%. This increased stratification further constrains vertical heat flux and the winter renewal of nutrients into the euphotic zone. One consequence of increased convergence is that both the depth of the nitracline (i.e. the depth where nitrate concentrations begin to increase from zero) and the depth of the chlorophyll maximum (which occurs slightly below the depth of the nitracline as here both nitrate and light are sufficient to allow primary production) have increased. Nitrate concentrations at the chlorophyll maximum depth have also recently decreased which suggests that the availability of light may play a progressively greater role in determining the depth at which primary production occurs. If these trends continue, assuming that the depth of the winter mixed layer does not deepen, such changes will negatively affect primary productivity as long as the Arctic Oscillation remains anticyclonic and freshwater continues to be stored in the Beaufort Gyre. These findings show that, under such conditions, the response of sea ice retreat in the basin interior is distinct and opposite to the response on adjacent continental shelves where shelf‐break upwelling will increase, bringing nitrate into the euphotic zone and enhancing production.
Aerosol optical properties from the Atmospheric Radiation Measurement Mobile Facility at Shouxian, China
Authors: Fan Xuehua , Chen Hongbin , Xia Xiangao , Li Zhanqing , Cribb Maureen
Published: December 2010

The Atmospheric Radiation Measurement program's Mobile Facility was deployed at Shouxian, China (32.56°N, 116.78°E, elevation 22.7 m), from May to December 2008. Aerosol optical properties derived from the Aerosol Observation System (AOS) measurements are analyzed. The median value of the light scattering coefficient (σsp) at 550 nm is 302.8 Mm−1. The lowest value of σsp appeared in the summer and was mainly due to strong wet deposition and upward transport. Averaged over the measurement period from May to July (arithmetic mean ± standard deviation), the aerosol light absorption coefficient, σap, is 29.4 ± 31.1 Mm−1 (550 nm) which is lower than most measurements made in urban areas in China but higher than those observed in background sites such as Shangdianzi, a suburb of Beijing. The mean single scattering albedo (ωo) is 0.92, which is greater than values found in the Pearl River Delta, the Yangtze Delta, and northern China, indicating less absorbing aerosols at the Shouxian site. The mean values and standard deviations of the Ångström exponent (α, 700–550 nm), the submicron scattering ratio (Rsp), and the hemispheric backscattering ratio (b) at 550 nm are 1.19 ± 0.23, 0.47 ± 0.15, and 0.101 ± 0.017, respectively. These values are lower than those observed at continental sites in the United States, implying the relatively large contributions of coarse mode particles at Shouxian. A distinct diurnal variation of aerosol optical properties is observed. Absorption coefficients are highest in the early morning and minimum values appear at noon. The ωo shows nearly the same cycle as the absorption coefficient but with the maximum and minimum reversed. Impacts of local agricultural residue burning and long‐range transport of dust on aerosol loading and properties are presented using Moderate Resolution Imaging Spectrometer (MODIS) fire spot data, MODIS level‐2 aerosol optical depth data and micropulse lidar data together with AOS data.
Relationship between bacterial diversity and function under biotic control: the soil pesticide degraders as a case study
Authors: Monard Cécile , Vandenkoornhuyse Philippe , Le Bot Barbara , Binet Françoise
Published: December 2010

In soil, the way biotic parameters impact the relationship between bacterial diversity and function is still unknown. To understand these interactions better, we used RNA-based stable-isotope probing to study the diversity of active atrazine-degrading bacteria in relation to atrazine degradation and to explore the impact of earthworm-soil engineering with respect to this relationship. Bulk soil, burrow linings and earthworm casts were incubated with 13C-atrazine. The pollutant degradation was quantified by liquid chromatography–mass spectrometry for 8 days, whereas active atrazine degraders were identified at 2 and 8 days by sequencing the 16S ribosomal RNA in the 13C-RNA fractions from the three soil microsites. An original diversity of atrazine degraders was found. Earthworm soil engineering greatly modified the taxonomic composition of atrazine degraders with dominance of α-, β- and γ-proteobacteria in burrow linings and of Actinobacteria in casts. Earthworm soil bioturbation increased the γ-diversity of atrazine degraders over the soil microsites generated. Atrazine degradation was enhanced in burrow linings in which primary atrazine degraders, closely related to Pelomonas aquatica, were detected only 2 days after atrazine addition. Atrazine degradation efficiency was not linearly related to the species richness of degraders but likely relied on keystone species. By enhancing soil heterogeneity, earthworms sustained high phylogenetic bacterial diversity and exerted a biotic control on the bacterial diversity–function relationships. Our findings call for future investigations to assess the ecological significance of biotic controls on the relationships between diversity and function on ecosystem properties and services (for example, soil detoxification) at larger scales.
Soil Microbial Biomass And Activity In A Cork Oak Savanna
Authors: Caldeira Maria , Fangueiro David , Lecomte Xavier , Bugalho Miguel , Coutinho João , Pereira João
Published: December 2010

Cork oak savannas are composed by a sparse tree canopy (30-70 trees/ha) and a grassland understory predominantly composed of C3 annuals that survive the hot and dry Mediterranean summers as seeds in the soil. Microbial communities can be more or less efficient at converting organic substrates into microbial biomass carbon depending on the quantity and quality of organic matter inputs. The cork oak savannas have two distinct types of plant litter that can affect soil microbial biomass and activity differently: herbaceous litter and the more recalcitrant woody plant litter resulting from the trees. Spatial variability of soil microbial biomass and activity due to the tree-grassland component of cork oak savannas were evaluated in order to better understand the soil carbon dynamics of these systems.To quantify changes in soil microbial biomass and activity, measurements were performed in a Cork oak savanna in Southern Portugal. At this site 8 plots were randomly established under mature cork oak trees and paired with 8 open grassland plots. During one year soil cores (0-10 cm) were monthly collected at each site for measuring soil microbial biomass C and other eco-physiology parameters.

Results/Conclusion

Soil microbial biomass carbon (Cmic) and nitrogen (Nmic) were always higher under the tree canopy than in the open grasslands. Organic carbon (Corg) was also higher under the tree canopies. The Cmic/Corg ratio relates to the microbial activity and its potential to mineralize organic substances. The Cmic/Corg ratio was lower under the tree canopies than in the open grasslands. Less microbial biomass was supported per unit of Corg. Basal activity was always higher under the canopy than in the open grassland.Trees scattered in the savanna function as islands inducing larger soil microbial communities and higher basal activity under the canopies. Lower Cmic/Corg ratio under the tree canopies suggests a more recalcitrant nature of the litter and a decrease in relative availability of organic matter under the trees.
Social Influences Are Associated With BMI and Weight Loss Intentions in Young Adults
Authors: Leahey Tricia M. , LaRose Jessica Gokee , Fava Joseph L. , Wing Rena R.
Published: December 2010

Christakis and colleagues have shown that health behaviors cluster in social networks and suggest social norms may account for the clustering. This study examined: (i) whether obesity clusters among young adults and whether social norms do in fact account for the clustering, and (ii) among overweight/obese (OW/OB) young adults, whether number of social contacts trying to lose weight is associated with weight loss intentions and whether social norms for weight loss account for this effect. Normal weight (NW) and OW/OB young adults (N = 288; 66% female; 75% white) completed measures assessing number of OW social contacts and social norms for obesity. OW/OB young adults also indicated number of OW social contacts currently trying to lose weight, social norms for weight loss, and weight loss intentions. Compared to NW, OW/OB young adults were more likely to have OW romantic partners and best friends and had more OW casual friends and family members (Ps < 0.05), but social norms for obesity did not differ between groups, and social norms did not mediate the relationship between OW social contacts and participants' weight status. However, among OW/OB young adults, having more social contacts trying to lose weight was associated with greater intention to lose weight (r = 0.20, P = 0.02) and social norms for weight loss fully mediated this effect (P < 0.01). This study is the first to show that social contacts and normative beliefs influence weight status and intentions for weight control in young adults. Findings underscore the importance of targeting social influence in the treatment and prevention of obesity in this high‐risk age group.
Differential Contribution of Dietary Fat and Monosaccharide to Metabolic Syndrome in the Common Marmoset (Callithrix jacchus)
Authors: Wachtman Lynn M. , Kramer Joshua A. , Miller Andrew D. , Hachey Audra M. , Curran Elizabeth H. , Mansfield Keith G.
Published: December 2010

There is a critical need for animal models to study aspects type 2 diabetes (T2D) pathogenesis and prevention. While the rhesus macaque is such an established model, the common marmoset has added benefits including reduced zoonotic risks, shorter life span, and a predisposition to birth twins demonstrating chimerism. The marmoset as a model organism for the study of metabolic syndrome has not been fully evaluated. Marmosets fed high‐fat or glucose‐enriched diets were followed longitudinally to observe effects on morphometric and metabolic measures. Effects on pancreatic histomorphometry and vascular pathology were examined terminally. The glucose‐enriched diet group developed an obese phenotype and a prolonged hyperglycemic state evidenced by a rapid and persistent increase in mean glycosylated hemoglobin (HgbA1c) observed as early as week 16. In contrast, marmosets fed a high‐fat diet did not maintain an obese phenotype and demonstrated a delayed increase in HgbA1c that did not reach statistical significance until week 40. Consumption of either diet resulted in profound pancreatic islet hyperplasia suggesting a compensation for increased insulin requirements. Although the high‐fat diet group developed atherosclerosis of increased severity, the presence of lesions correlated with glucose intolerance only in the glucose‐enriched diet group. The altered timing of glucose dysregulation, differential contribution to obesity, and variation in vascular pathology suggests mechanisms of effect specific to dietary nutrient content. Feeding nutritionally modified diets to common marmosets recapitulates aspects of metabolic disease and represents a model that may prove instrumental to elucidating the contribution of nutrient excess to disease development.
The Golgi apparatus: an organelle with multiple complex functions
Authors: Wilson Cathal , Venditti Rossella , Rega Laura R. , Colanzi Antonino , D'Angelo Giovanni , De Matteis M. Antonietta
Published: December 2010

Remarkable advances have been made during the last few decades in defining the organizational principles of the secretory pathway. The Golgi complex in particular has attracted special attention due to its central position in the pathway, as well as for its fascinating and complex structure. Analytical studies of this organelle have produced significant advances in our understanding of its function, although some aspects still seem to elude our comprehension. In more recent years a level of complexity surrounding this organelle has emerged with the discovery that the Golgi complex is involved in cellular processes other than the ‘classical’ trafficking and biosynthetic pathways. The resulting picture is that the Golgi complex can be considered as a cellular headquarters where cargo sorting/processing, basic metabolism, signalling and cell-fate decisional processes converge.
Malnutrition: Risks & Concerns in Dysphagia Management
Authors: Yarrow Linda , Garcia Jane Mertz
Published: December 2010

Malnutrition, particularly undernutrition, negatively affects health outcomes. Risk of malnutrition, often identified by a Registered Dietitian as part of a patient's dietary assessment, increases greatly in the presence of dysphagia. Patient characteristics that may be linked to malnutrition include advanced age, medical diagnoses, level of diet tolerated, actual calorie and protein intake, need for feeding assistance, weight changes, and quality of life issues. Many older adults may be malnourished at the time of their hospital admission or become so during the course of their medical care. Poor physical condition from malnutrition could negatively impact a patient's rehabilitation potential. This article highlights possible causes and effects of undernutrition and the importance of nutrition strategies to patient care through a case study illustration.
Maintaining SLPs as the Preferred Providers of Dysphagia Services: A Call to Action
Authors: Graner Darlene , Pressman Hilda , Wagner Lynne C. Brady
Published: December 2010

Speech-language pathologists (SLPs) in the general medical hospital setting spend approximately half of their time providing swallowing services. Other professions, including occupational therapists (OTs) and dietitians, promote themselves as disciplines well suited to assist patients with dysphagia. Responses to a survey distributed by the American Speech-Language-Hearing-Association (ASHA) in 2007 indicated that 83% of SLPs working in hospitals believed encroachment and defining professional boundaries was a problem. The highest level of personal experience with encroachment was with occupational therapy. Effective 2009, the American Occupational Therapy Association (AOTA) began offering Specialty Certification in Feeding, Eating and Swallowing (SCFES) to OTs and OTAs who meet specific educational and clinical experience requirements. This article reviews the many reasons why SLPs are the professionals best suited for assisting patients with swallowing disorders. It provides specific strategies to assist SLPs in promoting our discipline as the providers of dysphagia services.
Ventilation, Respiration, Pulmonary Diseases, and Swallowing
Authors: Coyle James L.
Published: December 2010

The respiratory and digestive functions of the upper aerodigestive tract (UAT) are inextricably linked, taking turns performing their life-supporting functions. The SLP is responsible for the management of swallowing disorders that increase health risks to patients, and necessarily need to understand and integrate into their evaluations and interventions, how the respiratory system works in health and disease, how to examine it, and how it changes in response to various conditions. This paper reviews the basics of respiratory anatomy and pulmonary function, respiratory-swallow coordination, and common pulmonary diseases in adults and how they affect swallowing function.
Exact quantum statistics for electronically nonadiabatic systems using continuous path variables
Authors: Ananth Nandini , Miller Thomas F.
Published: December 2010

We derive an exact, continuous-variable path integral (PI) representation of the canonical partition function for electronically nonadiabatic systems. Utilizing the Stock–Thoss (ST) mapping for an N-level system, matrix elements of the Boltzmann operator are expressed in Cartesian coordinates for both the nuclear and electronic degrees of freedom. The PI discretization presented here properly constrains the electronic Cartesian coordinates to the physical subspace of the mapping. We numerically demonstrate that the resulting PI–ST representation is exact for the calculation of equilibrium properties of systems with coupled electronic and nuclear degrees of freedom. We further show that the PI–ST formulation provides a natural means to initialize semiclassical trajectories for the calculation of real-time thermal correlation functions, which is numerically demonstrated in applications to a series of nonadiabatic model systems.
The polarizable point dipoles method with electrostatic damping: Implementation on a model system
Authors: Sala Jonàs , Guàrdia Elvira , Masia Marco
Published: December 2010

Recently, the use of polarizable force fields in Molecular Dynamics simulations has been gaining importance, since they allow a better description of heterogeneous systems compared to simple point charges force fields. Among the various techniques developed in the last years the one based on polarizable point dipoles represents one of the most used. In this paper, we review the basic technical issues of the method, illustrating the way to implement intramolecular and intermolecular damping of the electrostatic interactions, either with and without the Ewald summation method. We also show how to reduce the computational overhead for evaluating the dipoles, introducing to the state–of–the–art methods: the extended Lagrangian method and the always stable predictor corrector method. Finally we discuss the importance of screening the electrostatic interactions at short range, defending this technique against simpler approximations usually made. We compare results of density functional theory and classical force field–based Molecular Dynamics simulations of chloride in water.
Aspects of coherent states of nonlinear algebras
Authors: Shreecharan T. , Chaitanya K. V. S. Shiv
Published: December 2010

Various aspects of coherent states of nonlinear su(2) and su(1, 1) algebras are studied. It is shown that the nonlinear su(1, 1) Barut–Girardello and Perelomov coherent states are related by a Laplace transform. We then concentrate on the derivation and analysis of the statistical and geometrical properties of these states. The Berry's phase for the nonlinear coherent states is also derived.
Quantitative analysis of CO-humidity gas mixtures with self-heated nanowires operated in pulsed mode
Authors: Prades J. D. , Hernández-Ramírez F. , Fischer T. , Hoffmann M. , Müller R. , López N. , Mathur S. , Morante J. R.
Published: December 2010

Self-heating effect in individual metal oxide nanowires can be used to activate their response to gases with power consumptions below tenths of microwatts. The thermal response time of these devices is extremely fast (a few milliseconds) and it makes it possible to observe the kinetics of the interactions between the gas molecules and the metal oxide. In this work we demonstrate that such effects enable an experimental methodology to improve the selectivity of metal oxide-based sensors based on the analysis of their fast response dynamics. Specifically, this work jointly analyzes the magnitude and response time of SnO2 nanowire-based sensors to carbon monoxide (CO) and humidity (H2O) mixtures, proving that a quantitative analysis of CO–H2O gas blends can be achieved by modulating their work temperature through the self-heating effect.
DNA electrophoresis in confined, periodic geometries: A new lakes-straits model
Authors: Laachi Nabil , Dorfman Kevin D.
Published: December 2010

We present a method to study the dynamics of long DNA molecules inside a cubic array of confining spheres, connected through narrow openings. Our method is based on the coarse-grained, lakes-straits model of Zimm and is therefore much faster than Brownian dynamics simulations. In contrast to Zimm's approach, our method uses a standard stochastic kinetic simulation to account for the mass transfer through the narrow straits and the formation of new lakes. The different rates, or propensities, of the reactions are obtained using first-passage time statistics and a Monte Carlo sampling to compute the total free energy of the chain. The total free energy takes into account the self-avoiding nature of the chain as well as confinement effects from the impenetrable spheres. The mobilities of various chains agree with biased reptation theory at low and high fields. At moderate fields, confinement effects lead to a new regime of reptation where the mobility is a linear function of molecular weight and the dispersion is minimal.
Effect of metal diffusion on mechanoelectric property of ionic polymer-metal composite
Authors: Tiwari Rashi , Kim Kwang J.
Published: December 2010

Ionic polymer-metal composite (IPMC) manufactured through electroless deposition has distinct electrode intermediate and polymer layers. Models typically study the ion motion inside the polymer layer, neglecting the electrode and intermediate layers. However, it must be noted that IPMC properties are affected by the physics of each layer and the coupling between them. In this paper, a physical phenomenological model explicitly describing the role of each layer is developed. The model predicts (i) the mechanoelectric behavior, (ii) the frequency response, and (iii) the geometric scalability effect on IPMC.
Hydrodynamic effects on spinodal decomposition kinetics in planar lipid bilayer membranes
Authors: Fan Jun , Han Tao , Haataja Mikko
Published: December 2010

The formation and dynamics of spatially extended compositional domains in multicomponent lipid membranes lie at the heart of many important biological and biophysical phenomena. While the thermodynamic basis for domain formation has been explored extensively in the past, domain growth in the presence of hydrodynamic interactions both within the (effectively) two-dimensional membrane and in the three-dimensional solvent in which the membrane is immersed has received little attention. In this work, we explore the role of hydrodynamic effects on spinodal decomposition kinetics via continuum simulations of a convective Cahn–Hilliard equation for membrane composition coupled to the Stokes equation. Our approach explicitly includes hydrodynamics both within the planar membrane and in the three-dimensional solvent in the viscously dominated flow regime. Numerical simulations reveal that dynamical scaling breaks down for critical lipid mixtures due to distinct coarsening mechanisms for elongated versus more isotropic compositional lipid domains. The breakdown in scaling should be readily observable in experiments on model membrane systems.
Optical properties of light-hole excitons in GaN epilayers
Authors: Zhang Fan , Xu S. J. , Ning J. Q. , Zheng C. C. , Zhao D. G. , Yang H. , Che C. M.
Published: December 2010

Optical properties of light-hole free exciton (FXB) in GaN epilayers were investigated by using near-resonance photoluminescence (PL) and time-resolved PL techniques. In contrast to the case of off-resonance PL where only heavy-hole free excitons (FXA) have strong response, FXB band can be well resolved in the near-resonance PL spectra. The variable-temperature near-resonance PL spectra show that the linewidth of FXB broadens faster than the FXA with increasing temperature. Moreover, the luminescence lifetime of FXB is found to be shorter than that of FXA.
Band alignment of atomic layer deposited HfO2 on clean and N passivated germanium surfaces
Authors: Rumaiz Abdul K. , Woicik J. C. , Carini G. A. , Siddons D. P. , Cockayne E. , Huey E. , Lysaght P. S. , Fischer D. A. , Genova V.
Published: December 2010

Hard x-ray photoelectron spectroscopy has been used to study the band alignment between atomic layer deposited HfO2 on clean Ge (100) and nitrogen treated Ge (100) surfaces. The position of the valence-band maximum was determined by convolving theoretically calculated density of states from first-principles calculations and comparing with experimental valence-band data. Using Kraut’s method, the valence-band offsets were found to be 3.2±0.1 and 3.3±0.1 eV for the samples grown on clean and N passivated Ge, respectively. The oxide charge measured from capacitance-voltage measurements shows a significant increase between the two samples; however, the small change in the band offset between the two systems strongly indicates negligible contribution of the interface to the conduction/valence-band barrier and the band alignment of the heterojunctions.
Formation of large-scale structures in ablative Kelvin–Helmholtz instability
Authors: Wang L. F. , Ye W. H. , Don Wai-Sun , Sheng Z. M. , Li Y. J. , He X. T.
Published: December 2010

In this research, we studied numerically nonlinear evolutions of the Kelvin–Helmholtz instability (KHI) with and without thermal conduction, aka, the ablative KHI (AKHI) and the classical KHI (CKHI). The second order thermal conduction term with a variable thermal conductivity coefficient is added to the energy equation in the Euler equations in the AKHI to investigate the effect of thermal conduction on the evolution of large and small scale structures within the shear layer which separate the fluids with different velocities. The inviscid hyperbolic flux of Euler equation is computed via the classical fifth order weighted essentially nonoscillatory finite difference scheme and the temperature is solved by an implicit fourth order finite difference scheme with variable coefficients in the second order parabolic term to avoid severe time step restriction imposed by the stability of the numerical scheme. As opposed to the CKHI, fine scale structures such as the vortical structures are suppressed from forming in the AKHI due to the dissipative nature of the second order thermal conduction term. With a single-mode sinusoidal interface perturbation, the results of simulations show that the growth of higher harmonics is effectively suppressed and the flow is stabilized by the thermal conduction. With a two-mode sinusoidal interface perturbation, the vortex pairing is strengthened by the thermal conduction which would allow the formation of large-scale structures and enhance the mixing of materials. In summary, our numerical studies show that thermal conduction can have strong influence on the nonlinear evolutions of the KHI. Thus, it should be included in applications where thermal conduction plays an important role, such as the formation of large-scale structures in the high energy density physics and astrophysics.
Graphene quantum dots formed by a spatial modulation of the Dirac gap
Authors: Giavaras G. , Nori Franco
Published: December 2010

An electrostatic quantum dot cannot be formed in monolayer graphene because of the Klein tunneling. However, a dot can be formed with the help of a uniform magnetic field. As shown here, a spatial modulation of the Dirac gap leads to confined states with discrete energy levels, thus defining a dot, without applying external electric and magnetic fields. Gap-induced dot states can coexist and couple with states introduced by an electrostatic potential. This property allows the region in which the resulting states are localized to be tuned with the potential.
Asymmetric-mode competition in a relativistic backward wave oscillator with a coaxial slow-wave structure
Authors: Ge Xingjun , Zhong Huihuang , Qian Baoliang , Zhang Jun , Liu Lie , Gao Liang , Yuan Chengwei , He Juntao
Published: December 2010

The initial experimental results of an L-band relativistic backward wave oscillator with a coaxial slow-wave structure are presented. The asymmetric-mode-competition mechanism in the device is investigated theoretically and experimentally. It is shown that the diode voltage, guiding-magnetic field, and concentricity play a key role in the suppression and excitation of the asymmetric-mode (coaxial quasi-TE11 mode). In the experiments, the asymmetric-mode with a frequency of 2.05 GHz is suppressed and excited, which is in good agreement with the theoretical results.
Error-landscape-based multiobjective calibration of the Smagorinsky eddy-viscosity using high-Reynolds-number decaying turbulence data
Authors: Meyers Johan , Meneveau Charles , Geurts Bernard J.
Published: December 2010

A suite of large-eddy simulations (LESs) of decaying homogeneous isotropic turbulence at high Reynolds numbers is performed and compared to wind-tunnel experiments in the tradition of Comte-Bellot and Corrsin. The error-landscape approach is used for the evaluation of the Smagorinsky model, and the results are used to identify an optimal combination of model parameter and resolution in a statistically robust fashion. The use of experimental reference data in the error-landscape approach allows to evaluate the optimal Smagorinsky coefficient at high Reynolds numbers and to perform detailed comparisons with analytical predictions. We demonstrate, using a pseudospectral discretization, that the optimal so-called Smagorinsky trajectory obtained from the error-landscape analysis converges at high simulation resolutions to the high-Re theoretical Lilly prediction for the Smagorinsky coefficient. Using modified wavenumbers in the same spectral code, the current study also presents error-landscape results based on LES with “second-order” discretization errors. By slightly revising Lilly’s analysis, we show that including the effect of numerical discretization when evaluating the strain-rate tensor needed in the subgrid-scale model leads to a good prediction of the optimal Smagorinsky parameter obtained from the corresponding error-landscape. Using similar analytical tools, we further demonstrate that the dynamic procedure can also be adapted to better account for the effects of discretization and test-filter shape.
Collective phase chaos in the dynamics of interacting oscillator ensembles
Authors: Kuznetsov Sergey P. , Pikovsky Arkady , Rosenblum Michael
Published: December 2010

We study the chaotic behavior of order parameters in two coupled ensembles of self-sustained oscillators. Coupling within each of these ensembles is switched on and off alternately, while the mutual interaction between these two subsystems is arranged through quadratic nonlinear coupling. We show numerically that in the course of alternating Kuramoto transitions to synchrony and back to asynchrony, the exchange of excitations between two subpopulations proceeds in such a way that their collective phases are governed by an expanding circle map similar to the Bernoulli map. We perform the Lyapunov analysis of the dynamics and discuss finite-size effects.
Prey switching by stoats (Mustela erminea): a supplemental food experiment
Authors: Smith Des H. V. , Moller Henrik , Wilson Deborah J. , Murphy Elaine C.
Published: December 2010

Context
Prey switching by invasive carnivorans to changing food supply could severely impact on endemic prey of conservation importance, but experimental evidence for prey switching in carnivorans is rare. Stoats (Mustela erminea) were introduced to New Zealand and now threaten survival of many native birds, reptiles and invertebrates.
Aim
Our primary objective was to see whether abundant food caused stoats inhabiting an alpine grassland site to alter the rate at which they preyed upon weta (Orthoptera : Hemiandrus sp.), hares (Lepus europeus), birds and mice (Mus musculus).
Methods
We used dead rabbits as supplemental food in a before-after-control-impact experiment. Stoat scats were collected from a treatment and non-treatment site before and following food supplementation. Percentage frequency occurrence of the different prey types was assessed for the two sites during each experimental phase.
Conclusions
Stoats ate fewer ground weta and hares, the two most abundant prey types, when supplemental food was added. In contrast, consumption of mice remained relatively stable at both sites throughout the experiment, and the consumption of birds declined at both sites.
Implications
Our experiment suggests that stoats may continue to eat scarce endemic prey at similar per capita rates even when alternative prey are available. However, endemic prey that are locally or regionally abundant may be indirectly impacted by fluctuations in alternative prey.
Consequences of envenomation: red imported fire ants have delayed effects on survival but not growth of native fence lizards
Authors: Langkilde Tracy , Freidenfelds Nicole A.
Published: December 2010

Context Aggressive encounters, including those with venomous species, impose selective pressure on native species. Immediate lethal outcomes of these encounters have been the primary focus of research in this field. However, not all aggressive interactions result in immediate mortality, and indirect consequences of aggressive interactions may be an equally important but under-considered selective force. The red imported fire ant is a globally important venomous invader that imposes novel selective pressure on native communities. Aims We examined indirect effects of fire ant envenomation on native fence lizard growth rates and subsequent survival. Methods Fence lizards are subject to fire ant envenomation in the field when they eat fire ants (they are stung inside the mouth) and through fire ant attack (they are stung on the body). We quantified body sizes of adult lizards from fire ant-invaded and uninvaded sites. We then experimentally exposed hatchling fence lizards to the two modes of fire ant envenomation, and quantified their growth and survival over 1 year. Key results Lizards from fire ant-invaded sites were smaller than those from an uninvaded site, even at similar latitudes. However, in contrast to studies on other native taxa, we found no effect of fire ant venom on growth rates of lizards from naïve or fire ant-invaded populations. Lizards exposed to fire ant venom, through both eating and attack, experienced higher rates of delayed mortality, with 34% of lizards dying 1–11 weeks post-envenomation compared with 12% of lizards in the control treatment. These patterns were true for fire ant naïve populations as well as those exposed to fire ants for ~35 generations. Conclusions These results suggest that the smaller body sizes observed in fence lizards from fire ant-invaded sites are not a consequence of exposure to fire ant venom. However, fence lizards from both sites suffer delayed survival costs of fire ant envenomation. Implications The present study highlights the importance of considering indirect fitness consequences of aggressive encounters if we are to fully understand the ecological and evolutionary consequences of these interactions, and adequately manage and predict the impacts of invasive species.
Condensates in quantum chromodynamics and the cosmological constant
Authors: Brodsky Stanley J. , Shrock Robert
Published: December 2010

Casher and Susskind [Casher A, Susskind L (1974)
Phys Rev
9:436–460] have noted that in the light-front description, spontaneous chiral symmetry breaking is a property of hadronic wavefunctions and not of the vacuum. Here we show from several physical perspectives that, because of color confinement, quark and gluon condensates in quantum chromodynamics (QCD) are associated with the internal dynamics of hadrons. We discuss condensates using condensed matter analogues, the Anti de Sitter/conformal field theory correspondence, and the Bethe–Salpeter–Dyson–Schwinger approach for bound states. Our analysis is in agreement with the Casher and Susskind model and the explicit demonstration of “in-hadron” condensates by Roberts and coworkers [Maris P, Roberts CD, Tandy PC (1998)
Phys Lett B
420:267–273], using the Bethe–Salpeter–Dyson–Schwinger formalism for QCD-bound states. These results imply that QCD condensates give zero contribution to the cosmological constant, because all of the gravitational effects of the in-hadron condensates are already included in the normal contribution from hadron masses.
Reiterative AP2a activity controls sequential steps in the neural crest gene regulatory network
Authors: de Crozé Noémie , Maczkowiak Frédérique , Monsoro-Burq Anne H.
Published: December 2010

The neural crest (NC) emerges from combinatorial inductive events occurring within its progenitor domain, the neural border (NB). Several transcription factors act early at the NB, but the initiating molecular events remain elusive. Recent data from basal vertebrates suggest that
ap2
might have been critical for NC emergence; however, the role of AP2 factors at the NB remains unclear. We show here that AP2a initiates NB patterning and is sufficient to elicit a NB-like pattern in neuralized ectoderm. In contrast, the other early regulators do not participate in
ap2a
initiation at the NB, but cooperate to further establish a robust NB pattern. The NC regulatory network uses a multistep cascade of secreted inducers and transcription factors, first at the NB and then within the NC progenitors. Here we report that AP2a acts at two distinct steps of this cascade. As the earliest known NB specifier, AP2a mediates Wnt signals to initiate the NB and activate
pax3
; as a NC specifier, AP2a regulates further NC development independent of and downstream of NB patterning. Our findings reconcile conflicting observations from various vertebrate organisms. AP2a provides a paradigm for the reiterated use of multifunctional molecules, thereby facilitating emergence of the NC in vertebrates.
Multinodal regulation of the arcuate/paraventricular nucleus circuit by leptin
Authors: Ghamari-Langroudi Masoud , Srisai Dollada , Cone Roger D.
Published: December 2010

Melanocortin-4 receptor (MC4R) is critical for energy homeostasis, and the paraventricular nucleus of the hypothalamus (PVN) is a key site of MC4R action. Most studies suggest that leptin regulates PVN neurons indirectly, by binding to receptors in the arcuate nucleus or ventromedial hypothalamus and regulating release of products like α-melanocyte-stimulating hormone (α-MSH), neuropeptide Y (NPY), glutamate, and GABA from first-order neurons onto the MC4R PVN cells. Here, we investigate mechanisms underlying regulation of activity of these neurons under various metabolic states by using hypothalamic slices from a transgenic MC4R-GFP mouse to record directly from MC4R neurons. First, we show that in vivo leptin levels regulate the tonic firing rate of second-order MC4R PVN neurons, with fasting increasing firing frequency in a leptin-dependent manner. We also show that, although leptin inhibits these neurons directly at the postsynaptic membrane, α-MSH and NPY potently stimulate and inhibit the cells, respectively. Thus, in contrast with the conventional model of leptin action, the primary control of MC4R PVN neurons is unlikely to be mediated by leptin action on arcuate NPY/agouti-related protein and proopiomelanocortin neurons. We also show that the activity of MC4R PVN neurons is controlled by the constitutive activity of the MC4R and that expression of the receptor mRNA and α-MSH sensitivity are both stimulated by leptin. Thus, leptin acts multinodally on arcuate nucleus/PVN circuits to regulate energy homeostasis, with prominent mechanisms involving direct control of both membrane conductances and gene expression in the MC4R PVN neuron.