bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of North Atlantic – GIN Sea exchange on deglaciation evolution of the Atlantic Meridional Overturning Circulation
Authors: Cheng J. , Liu Z. , He F. , Otto-Bliesner B. L. , Colose C.
Published: August 2011

Abstract. In a transient simulation of the last deglaciation with a fully coupled model (TraCE-21000), an overshoot of the Atlantic Meridional Overturning Circulation (AMOC) is simulated and proposed as a key factor for the onset of the Bølling-Allerød (BA) warming event. There is collaborating evidence for an AMOC overshoot at the BA in various proxy reconstructions although the mechanism governing its behavior is not well understood. Here, we present two new sensitivity experiments to explicitly illustrate the impact of North Atlantic – GIN Sea exchange on the AMOC's deglacial evolution. Results show that this oceanic exchange dominates the convection restarting in the GIN Sea, the occurrence of the AMOC overshoot, and the full BA warming.
Bias correction of satellite rainfall estimates using a radar-gauge product – a case study in Oklahoma (USA)
Authors: Tesfagiorgis K. , Mahani S. E. , Krakauer N. Y. , Khanbilvardi R.
Published: August 2011

Abstract. Hourly Satellite Precipitation Estimates (SPEs) may be the only available source of information for operational hydrologic and flash flood prediction due to spatial limitations of radar and gauge products. SPEs are prone to larger systematic errors and more uncertainty sources in comparison with ground based radar and gauge precipitation products. The present work develops an approach to seamlessly blend satellite, radar and gauge products to fill gaps in ground-based data. To mix different rainfall products, the bias of any of the products relative to each other should be removed. The study presents and tests a proposed ensemble-based method which aims to estimate spatially varying multiplicative biases in hourly SPEs using a radar-gauge rainfall product and compare it with previously used bias correction methods. Bias factors were calculated for a randomly selected sample of rainy pixels in the study area. Spatial fields of estimated bias were generated taking into account spatial variation and random errors in the sampled values. Bias field parameters were determined on a daily basis using the shuffled complex evolution optimization algorithm. To include more error sources, ensembles of bias factors were generated and applied before bias field generation. We demonstrate this method using two satellite-based products, CPC Morphing (CMORPH) and Hydro-Estimator (HE), and a radar-gauge rainfall Stage-IV (ST-IV) dataset for several rain events in 2006 over Oklahoma. The method was compared with 3 simpler methods for bias correction: mean ratio, maximum ratio and spatial interpolation without ensembles. Bias ratio, correlation coefficient, root mean square error and mean absolute difference are used to evaluate the performance of the different methods. Results show that: (a) the methods of maximum ratio and mean ratio performed variably and did not improve the overall correlation with the ST-IV in any of the rainy events; (b) the method of interpolation was consistently able to improve all the performance criteria; (c) the method of ensembles outperformed the other 3 methods.
A comparison of the causes, effects and aftermaths of the coastal flooding of England in 1953 and France in 2010
Authors: Lumbroso D. M. , Vinet F.
Published: August 2011

Abstract. This paper provides a comparison of the causes, effects and aftermaths of the coastal flooding that occurred on the east coast of England in 1953 and the west coast of France in 2010 that resulted in 307 and 47 deaths respectively. The causes of both events are strikingly similar. Both were caused by a combination of high tides, low atmospheric pressure, high winds and the failure of poorly maintained flood defences. In both cases the number of deaths was related to the vulnerability of the buildings and people. Buildings in the flood zones were often single storey bungalows and the people who died were mostly over 60 yr of age. Both tragedies were national disasters. The 1953 flood in England acted as a catalyst for an acceleration in flood risk management policy and practice. It resulted in: the development of a Storm Tide Warning System for the east coast of England; the setting of new design standards for coastal flood defences; increased investment in improving coastal defences; and a substantial new research effort into coastal processes, protection and forecasting. In France there has also been an episodic shift in flood risk management policy with the focus falling on: control of urban developments in areas at risk of flooding; improved coastal forecasting and warning; strengthening of flood defences; and developing a "culture of risk awareness". This paper outlines the lessons that can be learnt from the two events and provides recommendations concerning how future loss of life as a result of coastal flooding can be reduced.
Narcolepsy onset is seasonal and increased following the 2009 H1N1 pandemic in china
Authors: Han Fang , Lin Ling , Warby Simon C. , Faraco Juliette , Li Jing , Dong Song X. , An Pei , Zhao Long , Wang Ling H. , Li Qian Y. , Yan Han , Gao Zhan C. , Yuan Yuan , Strohl Kingman P. , Mignot Emmanuel
Published: August 2011

Objective:

Narcolepsy is caused by the loss of hypocretin/orexin neurons in the hypothalamus, which is likely the result of an autoimmune process. Recently, concern has been raised over reports of narcolepsy in northern Europe following H1N1 vaccination.

Methods:

The study is a retrospective analysis of narcolepsy onset in subjects diagnosed in Beijing, China (1998–2010). Self‐reported month and year of onset were collected from 629 patients (86% children). Graphical presentation, autocorrelations, chi‐square, and Fourier analysis were used to assess monthly variation in onset. Finally, 182 patients having developed narcolepsy after October 2009 were asked for vaccination history.

Results:

The occurrence of narcolepsy onset was seasonal, significantly influenced by month and calendar year. Onset was least frequent in November and most frequent in April, with a 6.7‐fold increase from trough to peak. Studying year‐to‐year variation, we found a 3‐fold increase in narcolepsy onset following the 2009 H1N1 winter influenza pandemic. The increase is unlikely to be explained by increased vaccination, as only 8 of 142 (5.6%) patients recalled receiving an H1N1 vaccination. Cross‐correlation indicated a significant 5‐ to 7‐month delay between the seasonal peak in influenza/cold or H1N1 infections and peak in narcolepsy onset occurrences.

Interpretation:

In China, narcolepsy onset is highly correlated with seasonal and annual patterns of upper airway infections, including H1N1 influenza. In 2010, the peak seasonal onset of narcolepsy was phase delayed by 6 months relative to winter H1N1 infections, and the correlation was independent of H1N1 vaccination in the majority of the sample. ANN NEUROL 2011;
A Series of Hyperbranched Polytriazoles Containing Perfluoroaromatic Rings from AB2‐Type Monomers: Convenient Syntheses by Click Chemistry under Copper(I) Catalysis and Enhanced Optical Nonlinearity
Authors: Wu Wenbo , Fu Yingjie , Wang Can , Ye Cheng , Qin Jingui , Li Zhen
Published: August 2011

In this paper, four new hyperbranched polytriazoles containing azo moieties, derived from different AB2‐type monomers, were successfully prepared through the “click” chemistry reaction under copper(I) catalysis by modifying the synthetic route. The polymers were soluble in organic solvents and exhibited good second‐order nonlinear optical (NLO) properties. Thanks to the self‐assembly of perfluoroaromatic moieties in the periphery, HP2 showed the best NLO properties, with the d33 value as high as 145.0 pm V−1.
Immobilization of Candida rugosa lipase on poly(3-hydroxybutyrate-co-hydroxyvalerate): a new eco-friendly support
Authors: Cabrera-Padilla Rebeca Y , Lisboa Milena C , Fricks Alini T , Franceschi Elton , Lima Alvaro S , Silva Daniel P , Soares Cleide M F
Published: August 2011

The overall objective of this study is to evaluate the morphological [scanning electron microscopy (SEM)], physicochemical [differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), chemical composition analysis, Fourier-transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR)], and biochemical properties of Candida rugosa lipase (CRL) immobilized on a natural biopolymer poly(3-hydroxybutyrate-co-hydroxyvalerate) (PHBV) in aqueous solution. CRL was immobilized by physical adsorption with efficiency of 30%. Compared with free CRL enzyme, there were slight changes in immobilized CRL activity as a function of temperature (from 37°C to 45°C), but a similar optimal pH value of 7.0. Inactivation rate constants for immobilized CRL enzyme were 0.009 and 0.334 h−1, and half-lives were 77 and 2 h at 40°C and 60°C, respectively. Kinetic parameters obtained for immobilized CRL include the Michaelis–Menten constant of K  m = 213.18 mM and maximum reaction velocity of V  max = 318.62 U/g. The operational stability of immobilized CRL was tested repeatedly, and after 12 cycles of reuse, the enzyme retained 50% activity. Based on our results, we propose that PHBV-immobilized CRL could serve as a promising biocatalyst in several industrial applications.
Improved Estimation of Oil, Linoleic and Oleic Acid and Seed Hull Fractions in Safflower by NIRS
Authors: Rudolphi Sabine , Becker Heiko C. , Schierholt Antje , von Witzke‐Ehbrecht Sabine
Published: August 2011

Near‐infrared reflectance spectroscopy (NIRS) of intact seeds allows the non‐destructive estimation of seed quality parameters which is highly desirable in plant breeding. Together with yield, oil content and quality, a main aim in safflower (Carthamus tinctorius L.) breeding is the selection of genotypes with a low percentage of empty seeds even under cooler climates. We developed NIRS calibrations for seed oil content, oleic and linoleic acid content, the seed hull fraction and the percentage of empty seeds using seed meal and intact seeds. For the different calibrations 108–534 samples from a safflower breeding program with lines adapted to German conditions, were analyzed with reference analyses (Soxhlet, gas chromatography), and scanned by NIRS as intact seeds and seed meal. Calibration equations were developed and tested through cross validation. The coefficient of determination of the calibration (R2) for intact seeds ranged from 0.91(oil content), 0.90 (seed hull fraction), 0.84 (empty seeds), 0.73 (linoleic acid) to 0.68 (oleic acid). The coefficient of determination of the cross validation was higher for seed meal than for intact seeds except for the parameter seed hull fraction. The results show that NIRS calibrations are applicable in safflower breeding programs for a fast screening.
Pain sensitivity and modulation in primary insomnia
Authors: Haack M. , Scott‐Sutherland J. , Santangelo G. , Simpson N.S. , Sethna N. , Mullington J.M.
Published: August 2011

Sleep of good quantity and quality is considered a biologically important resource necessary to maintain homeostasis of pain‐regulatory processes. To assess the role of chronic sleep disturbances in pain processing, we conducted laboratory pain testing in subjects with primary insomnia.

Seventeen participants with primary insomnia (mean ± SEM 22.6 ± 0.9 yrs, 11 women) were individually matched with 17 healthy participants. All participants wore an actigraph device over a 2‐week period and completed daily sleep and pain diaries. Laboratory pain testing was conducted in a controlled environment and included (1) warmth detection threshold testing, (2) pain sensitivity testing (threshold detection for heat and pressure pain), and (3) tests to access pain modulatory mechanisms (pain facilitation and inhibition).

Primary insomnia subjects reported experiencing spontaneous pain on twice as many days as healthy controls during the at‐home recording phase (p < 0.05). During laboratory testing, primary insomnia subjects had lower pain thresholds than healthy controls (p < 0.05 for heat pain detection threshold, p < 0.08 for pressure pain detection threshold). Unexpectedly, pain facilitation, as assessed with temporal summation of pain responses, was reduced in primary insomnia compared to healthy controls (p < 0.05). Pain inhibition, as assessed with the diffuse noxious inhibitory control paradigm (DNIC), was attenuated in insomnia subjects when compared to controls (p < 0.05).

Based on these findings, we propose that pain‐inhibitory circuits in patients with insomnia are in a state of constant activation to compensate for ongoing subclinical pain. This constant activation ultimately may result in a ceiling effect of pain‐inhibitory efforts, as indicated by the inability of the system to adequately function during challenge.
Modeling of electromagnetic waves in axisymmetric geometry using a Laguerre spectral method
Authors: Mastryukov A.F.
Published: August 2011

A spectral method for modeling high-frequency electromagnetic waves in axisymmetric geometry is proposed. The method is based on the expansion of the solutions of Maxwell’s equations in Laguerre functions in the time region.

The spectral method is used to solve Maxwell’s equations for both 2D media and stratified media. In the case of stratified media, a Fourier–Bessel expansion in the radial variable is used. The effectiveness of the spectral and finite-difference methods is compared. Harmonic solutions and solitary solutions by the Laguerre method are considered, and the dynamics of monochromatic and broadband electromagnetic pulses are examined.
Bayesian Fundamentalism or Enlightenment? On the explanatory status and theoretical contributions of Bayesian models of cognition
Authors: Jones Matt , Love Bradley C.
Published: August 2011

The prominence of Bayesian modeling of cognition has increased recently largely because of mathematical advances in specifying and deriving predictions from complex probabilistic models. Much of this research aims to demonstrate that cognitive behavior can be explained from rational principles alone, without recourse to psychological or neurological processes and representations. We note commonalities between this rational approach and other movements in psychology – namely, Behaviorism and evolutionary psychology – that set aside mechanistic explanations or make use of optimality assumptions. Through these comparisons, we identify a number of challenges that limit the rational program's potential contribution to psychological theory. Specifically, rational Bayesian models are significantly unconstrained, both because they are uninformed by a wide range of process-level data and because their assumptions about the environment are generally not grounded in empirical measurement. The psychological implications of most Bayesian models are also unclear. Bayesian inference itself is conceptually trivial, but strong assumptions are often embedded in the hypothesis sets and the approximation algorithms used to derive model predictions, without a clear delineation between psychological commitments and implementational details. Comparing multiple Bayesian models of the same task is rare, as is the realization that many Bayesian models recapitulate existing (mechanistic level) theories. Despite the expressive power of current Bayesian models, we argue they must be developed in conjunction with mechanistic considerations to offer substantive explanations of cognition. We lay out several means for such an integration, which take into account the representations on which Bayesian inference operates, as well as the algorithms and heuristics that carry it out. We argue this unification will better facilitate lasting contributions to psychological theory, avoiding the pitfalls that have plagued previous theoretical movements.
The myth of computational level theory and the vacuity of rational analysis
Authors: Anderson Barton L.
Published: August 2011

I extend Jones & Love's (J&L's) critique of Bayesian models and evaluate the conceptual foundations on which they are built. I argue that: (1) the “Bayesian” part of Bayesian models is scientifically trivial; (2) “computational level” theory is a fiction that arises from an inappropriate programming metaphor; and (3) the real scientific problems lie outside Bayesian theorizing.
Maybe this old dinosaur isn’t extinct: What does Bayesian modeling add to associationism?
Authors: Baetu Irina , Barberia Itxaso , Murphy Robin A. , Baker A. G.
Published: August 2011

We agree with Jones & Love (J&L) that much of Bayesian modeling has taken a fundamentalist approach to cognition; but we do not believe in the potential of Bayesianism to provide insights into psychological processes. We discuss the advantages of associative explanations over Bayesian approaches to causal induction, and argue that Bayesian models have added little to our understanding of human causal reasoning.
The imaginary fundamentalists: The unshocking truth about Bayesian cognitive science
Authors: Chater Nick , Goodman Noah , Griffiths Thomas L. , Kemp Charles , Oaksford Mike , Tenenbaum Joshua B.
Published: August 2011

If Bayesian Fundamentalism existed, Jones & Love's (J&L's) arguments would provide a necessary corrective. But it does not. Bayesian cognitive science is deeply concerned with characterizing algorithms and representations, and, ultimately, implementations in neural circuits; it pays close attention to environmental structure and the constraints of behavioral data, when available; and it rigorously compares multiple models, both within and across papers. J&L's recommendation of Bayesian Enlightenment corresponds to past, present, and, we hope, future practice in Bayesian cognitive science.
Osiander's psychology
Authors: Glymour Clark
Published: August 2011

Bayesian psychology follows an old instrumentalist tradition most infamously illustrated by Osiander's preface to Copernicus's masterpiece. Jones & Love's (J&L's) criticisms are, if anything, understated, and their proposals overoptimistic.
Probabilistic models as theories of children's minds
Authors: Gopnik Alison
Published: August 2011

My research program proposes that children have representations and learning mechanisms that can be characterized as causal models of the world – coherent, structured hypotheses with consistent relationships to probabilistic patterns of evidence. We also propose that Bayesian inference is one mechanism by which children learn these models from data. These proposals are straightforward psychological hypotheses and far from “Bayesian Fundamentalism.”
In praise of secular Bayesianism
Authors: Heit Evan , Erickson Shanna
Published: August 2011

It is timely to assess Bayesian models, but Bayesianism is not a religion. Bayesian modeling is typically used as a tool to explain human data. Bayesian models are sometimes equivalent to other models, but have the advantage of explicitly integrating prior hypotheses with new observations. Any lack of representational or neural assumptions may be an advantage rather than a disadvantage.
Come down from the clouds: Grounding Bayesian insights in developmental and behavioral processes
Authors: Jenkins Gavin W. , Samuelson Larissa K. , Spencer John P.
Published: August 2011

According to Jones & Love (J&L), Bayesian theories are too often isolated from other theories and behavioral processes. Here, we highlight examples of two types of isolation from the field of word learning. Specifically, Bayesian theories ignore emergence, critical to development theory, and have not probed the behavioral details of several key phenomena, such as the “suspicious coincidence” effect.
Taking the rationality out of probabilistic models
Authors: Rehder Bob
Published: August 2011

Rational models vary in their goals and sources of justification. While the assumptions of some are grounded in the environment, those of others – which I label probabilistic models – are induced and so require more traditional sources of justification, such as generalizability to dissimilar tasks and making novel predictions. Their contribution to scientific understanding will remain uncertain until standards of evidence are clarified.
The influences of metabotropic receptor activation on cellular signaling and synaptic function in amacrine cells
Authors: GLEASON EVANNA
Published: August 2011

Amacrine cells receive glutamatergic input from bipolar cells and GABAergic, glycinergic, cholinergic, and dopaminergic input from other amacrine cells. Glutamate, GABA, glycine, and acetylcholine (ACh) interact with ionotropic receptors and it is these interactions that form much of the functional circuitry in the inner retina. However, glutamate, GABA, ACh, and dopamine also activate metabotropic receptors linked to second messenger pathways that have the potential to modify the function of individual cells as well as retinal circuitry. Here, the physiological effects of activating dopamine receptors, metabotropic glutamate receptors, GABABreceptors, and muscarinic ACh receptors on amacrine cells will be discussed. The retina also expresses metabotropic receptors and the biochemical machinery associated with the synthesis and degradation of endocannabinoids and sphingosine-1-phosphate (S1P). The effects of activating cannabinoid receptors and S1P receptors on amacrine cell function will also be addressed.
High Contrast Magnetic and Nonmagnetic Sample Current Microscopy for Bulk and Transparent Samples Using Soft X-Rays
Authors: Nolle Daniela , Weigand Markus , Schütz Gisela , Goering Eberhard
Published: August 2011

The soft X-ray energy range provides important detection capabilities for a wide range of material systems, e.g., the K-edge behavior of biological materials or magnetic contrast imaging at the L2,3- and M4,5-edges, respectively, using the X-ray magnetic circular dichroism effect. The need for thinned samples due to the short penetration depth of soft X-rays is a limiting factor for microscopic imaging in transmission microscopy. In contrast, the more surface sensitive photoelectron emission microscopy allows the X-ray microscopic investigation of nontransparent bulk samples, but only small magnetic fields and very smooth surfaces are possible. As both high magnetic fields as well as bulk samples are important for magnetic imaging, we present total electron yield (TEY) microscopy results using the total sample current detection performed at the new ultra high vacuum scanning microscope “MAXYMUS” at HZB/BESSY II. We compare synchronous measurements in TEY and transmission mode to demonstrate the capabilities of TEY microscopy. Pictures and spectra with high absorption contrast and three-dimensional-like edge enhancement are observed as known for scanning electron microscopy. This unveils details on smallest length scales of the surface morphology. Furthermore, surface sensitive in- and out-of-plane magnetic TEY measurements at nontransparent samples are shown.
Comment on Lobell et al "Climate Trends and Global Crop Production Since 1980"
Authors: Semenov Mikhail , Shewry Peter
Published: August 2011

Lobel et al (ScienceXpress) analysed changes in global yields which can be attributed to climate change trend, and reported a 5.5% decline in global wheat production since 1980. We have failed to confirm these results using a process-based crop model, which showed no decline in wheat yield since the 1950s at two European sites. The Lobel et al conclusions are not valid due to the limitations of the regression analysis used.
Relationship Between the Bertin Index to Estimate Visceral Adipose Tissue From Dual‐Energy X‐Ray Absorptiometry and Cardiometabolic Risk Factors Before and After Weight Loss
Authors: Karelis Antony D. , Rabasa‐Lhoret Rémi , Pompilus Roseline , Messier Virginie , Strychar Irene , Brochu Martin , Aubertin‐Leheudre Mylene
Published: August 2011

The purpose of this study was to investigate the relationship between visceral adipose tissue (VAT), estimated with the Bertin index obtained from dual‐energy X‐ray absorptiometry (DXA), with cardiometabolic risk factors before and after a weight loss program and compare it with VAT measured with computed tomography (CT) scan. The study population for this analysis included 92 nondiabetic overweight and obese sedentary postmenopausal women (age: 58.1 ± 4.7 years, BMI: 31.8 ± 4.2 kg/m2) participating in a weight loss intervention that consisted of a caloric restricted diet with and without resistance training (RT). We measured (i) VAT using CT scan, (ii) body composition (using DXA) from which the Bertin index was calculated, (iii) cardiometabolic risk factors such as insulin sensitivity (using the hyperinsulinenic—euglycemic clamp technique), peak oxygen consumption, blood pressure, plasma lipids, C‐reactive protein as well as fasting glucose and insulin. VAT levels for both methods significantly decreased after the weight loss intervention. Furthermore, no differences in VAT levels between both methods were observed before (88.0 ± 25.5 vs. 83.8 ± 22.0 cm2) and after (76.8 ± 27.8 vs. 73.6 ± 23.2 cm2) the weight loss intervention. In addition, the percent change in VAT levels after the weight loss intervention was similar between both methods (−13.0 ± 16.5 vs. −12.5 ± 12.6%). Moreover, similar relationships were observed between both measures of VAT with cardiometabolic risk factors before and after the weight loss intervention. Finally, results from the logistic regression analysis consistently showed that fat mass and lean body mass were independent predictors of pre‐ and post‐VAT levels for both methods in our cohort. In conclusion, estimated visceral fat levels using the Bertin index may be able to trace variations of VAT after weight loss. This index also shows comparable relationships with cardiometabolic risk factors when compared to VAT measured using CT scan.
Spheno-Orbital Meningioma Resection and Reconstruction: The Role of Piezosurgery and Premolded Titanium Mesh
Authors: Jung Susana Heredero , Ferrer Alicia Dean , Vela Juan Solivera , Granados Francisco Alamillos
Published: August 2011

We present the clinical case of a patient with a spheno-orbital meningioma. Literature review of the treatment options, including the application of piezoelectric or ultrasound surgery and orbital reconstruction after meningioma resection, is also presented. Complete resection was performed by means of a frontotemporal craniotomy and an orbitozygomatic approach. Piezoelectric osteotomy was used around the optic nerve canal and the superior orbital fissure to minimize the damage to soft tissues. Orbital wall reconstruction was done using a titanium mesh previously premolded using a skull model. The superior orbital rim was reconstructed with calvarial bone grafts, and the sphenotemporal bone defect was covered with a titanium mesh cranioplasty. Ultrasonic vibrations to perform osteotomies in craniofacial surgery provide an interesting tool to reduce damage to surrounding soft tissues. Reconstruction of the roof and lateral orbital wall with premolded titanium meshes with a skull model is a safe and easy method to achieve a good orbital reconstruction and to avoid secondary sequelae.
New signal processing technique for density profile reconstruction using reflectometry
Authors: Clairet F. , Ricaud B. , Briolle F. , Heuraux S. , Bottereau C.
Published: August 2011

Reflectometry profile measurement requires an accurate determination of the plasma reflected signal. Along with a good resolution and a high signal to noise ratio of the phase measurement, adequate data analysis is required. A new data processing based on time-frequency tomographic representation is used. It provides a clearer separation between multiple components and improves isolation of the relevant signals. In this paper, this data processing technique is applied to two sets of signals coming from two different reflectometer devices used on the Tore Supra tokamak. For the standard density profile reflectometry, it improves the initialization process and its reliability, providing a more accurate profile determination in the far scrape-off layer with density measurements as low as 1016 m−1. For a second reflectometer, which provides measurements in front of a lower hybrid launcher, this method improves the separation of the relevant plasma signal from multi-reflection processes due to the proximity of the plasma.
Velocity-scaling optimized replica exchange molecular dynamics of proteins in a hybrid explicit/implicit solvent
Authors: Wang Jinan , Zhu Weiliang , Li Guohui , Hansmann Ulrich H. E.
Published: August 2011

We propose a scheme for replica exchange molecular dynamics of proteins in explicit solvent that minimizes the number of required replicas using velocity rescaling. Our approach relies on a hybrid method where the protein evolves at each temperature in an explicit solvent, but replica exchange moves utilize an implicit solvent term. The two terms are coupled through the velocity rescaling. We test the efficiency of this approach for a common test case, the trp-cage protein.
Magnetic and elastic properties of CoFe2O4- polydimethylsiloxane magnetically oriented elastomer nanocomposites
Authors: Soledad Antonel P. , Jorge Guillermo , Perez Oscar E. , Butera Alejandro , Gabriela Leyva A. , Martín Negri R.
Published: August 2011

Magnetic elastic structured composites were prepared by using CoFe2O4 ferromagnetic and superparamagnetic nanoparticles as fillers in polydimethylsiloxane (PDMS) matrixes, which were cured in the presence of a uniform magnetic field. Cobalt-iron oxide nanoparticles of three different average sizes (between 2 and 12 nm) were synthesized and characterized. The smallest nanoparticles presented superparamagnetic behavior, with a blocking temperature of approximately 75 K, while larger particles are already blocked at room temperature. Macroscopically structured-anisotropic PDMS-CoFe2O4 composites were obtained when curing the dispersion of the nanoparticles in the presence of a uniform magnetic field (0.3 T). The formation of the particle’s chains (needles) orientated in the direction of the magnetic field was observed only when loading with the larger magnetically blocked nanoparticles. The SEM images show that the needles are formed by groups of nanoparticles which retain their original average size. The Young’s moduli of the structured composites are four times larger when measured along the oriented needles than in the perpendicular direction. Magnetization (VSM) and ferromagnetic resonance curves of the structured composites were determined as a function of the relative orientation between the needles and the probe field. The remanence magnetization was 30% higher when measured parallel to the needles, while the coercive field remains isotropic. These observations are discussed in terms of the individual nanoparticle’s properties and its aggregation in the composites.
Note: Continuous synthesis of uniform vertical graphene on cylindrical surfaces
Authors: Bo Zheng , Cui Shumao , Yu Kehan , Lu Ganhua , Mao Shun , Chen Junhong
Published: August 2011

This note describes a new reactor design for continuous synthesis of vertically oriented graphene (VG) sheets on cylindrical wire substrates using an atmospheric plasma-enhanced chemical vapor deposition (PECVD) system. Through combining a U-shaped reactor design with “dynamic mode” synthesis featuring simultaneous rotational and axial movements of the metallic wire substrate, the new setup can enable continuous synthesis of VG sheets on the wire surface with remarkable uniformity in both circumferential and axial directions. In contrast, synthesis of VG at “static mode” with a fixed substrate can only lead to non-uniform growth of VG sheets on the wire surface. Potential applications of the resulting uniform-VG-coated metallic wire could include field emitters, field-ionization-based neutral atom detectors, and indoor corona discharges.
CdS quantum dots grown by in situ chemical bath deposition for quantum dot-sensitized solar cells
Authors: Woo Jung Sung , Kim Jae-Hong , Kim Hyunsoo , Choi Chel-Jong , Ahn Kwang-Soon
Published: August 2011

CdS quantum dots (QDs) are grown on mesoporous TiO2 films by 3 to 13 repeated cycles of in situ chemical bath deposition (CBD). The overall energy conversion efficiency of CdS quantum dot-sensitized solar cells (QD-SSCs) increases as the number of cycles increases to the eight — peaking at 2.13%. This is attributable to efficient light harvesting and charge-collection resulting from enhanced light absorption and faster charge transport. However a further increase of CBD cycles to thirteen reduces QD-SSCs performance, despite better light absorption in the long wavelengths. This is attributed to decreased charge-injection efficiency, which is due to reduced driving forces of carrier injection, increased trap-mediated recombination in the QDs, and hindered ion transport.
Nuclear magnetic resonance studies on the rotational and translational motions of ionic liquids composed of 1-ethyl-3-methylimidazolium cation and bis(trifluoromethanesulfonyl)amide and bis(fluorosulfonyl)amide anions and their binary systems including lithium salts
Authors: Hayamizu Kikuko , Tsuzuki Seiji , Seki Shiro , Umebayashi Yasuhiro
Published: August 2011

Room temperature ionic liquids (ILs) are stable liquids composed of anions and cations. 1-ethyl-3-methyl-imidazolium (EMIm, EMI) is a popular and important cation that produces thermally stable ILs with various anions. In this study two amide-type anions, bis(trifluoro-methanesulfonyl)amide [N(SO2CF3)2, TFSA, TFSI, NTf2, or Tf2N] and bis(fluorosulfonyl)amide [(N(SO2F)2, FSA, or FSI] were investigated by multinuclear NMR spectroscopy. In addition to EMIm-TFSA and EMIm-FSA, lithium-salt-doped binary systems were prepared (EMIm-TFSA-Li and EMIm-FSA-Li). The spin-lattice relaxation times (T1) were measured by 1H, 19F, and 7Li NMR spectroscopy and the correlation times of 1H NMR, τc(EMIm) (8 × 10−10 to 3 × 10−11 s) for the librational molecular motion of EMIm and those of 7Li NMR, τc(Li) (5 × 10−9 to 2 × 10−10 s) for a lithium jump were evaluated in the temperature range between 253 and 353 K. We found that the bulk viscosity (η) versus τc(EMIm) and cation diffusion coefficient DEMIm versus the rate 1/τc(EMIm) have good relationships. Similarly, linear relations were obtained for the η versus τc(Li) and the lithium diffusion coefficient DLi versus the rate 1/τc(Li). The mean one-jump distances of Li were calculated from τc(Li) and DLi. The experimental values for the diffusion coefficients, ionic conductivity, viscosity, and density in our previous paper were analyzed by the Stokes-Einstein, Nernst-Einstein, and Stokes-Einstein-Debye equations for the neat and binary ILs to clarify the physicochemical properties and mobility of individual ions. The deviations from the classical equations are discussed.
Electronic transport in doped pyrenyl carbazole
Authors: Ali Farman , Periasamy N. , Patankar Meghan P. , Narasimhan K. L.
Published: August 2011

In this paper, we report on electronic transport and impedance measurements on thin films of unintentionally hole doped 3,6-dipyrenyl-N-hexylcarbazole. Evidence for doping from dc conductivity, ESR, and capacitance measurements is presented. From a study of the bias, temperature and frequency dependence of capacitance, we estimate the integrated density of states above the Fermi level to be 1017/cm3. This is also the doping concentration in these samples.
A time-of-flight backscattering spectrometer at the Spallation Neutron Source, BASIS
Authors: Mamontov E. , Herwig K. W.
Published: August 2011

We describe the design and current performance of the backscattering silicon spectrometer (BASIS), a time-of-flight backscattering spectrometer built at the spallation neutron source (SNS) of the Oak Ridge National Laboratory (ORNL). BASIS is the first silicon-based backscattering spectrometer installed at a spallation neutron source. In addition to high intensity, it offers a high-energy resolution of about 3.5 μeV and a large and variable energy transfer range. These ensure an excellent overlap with the dynamic ranges accessible at other inelastic spectrometers at the SNS.
Limitation of the electron emission in an ion diode with magnetic self-insulation
Authors: Pushkarev A. I. , Isakova Yu. I. , Guselnikov V. I.
Published: August 2011

The results of a study of the generation of a pulsed ion beam of gigawatt power formed by a diode with an explosive-emission potential electrode in a mode of magnetic self-insulation are presented. The studies were conducted at the TEMP-4M ion accelerator set in double pulse formation mode: the first pulse was negative (300–500 ns and 100–150 kV) and the second, positive (150 ns and 250–300 kV). The ion current density was 20–40 A/cm2; the beam composition was protons and carbon ions. It was shown that plasma is effectively formed over the entire working surface of the graphite potential electrode. During the ion beam generation, a condition of magnetic cutoff of electrons along the entire length of the diode (B/Bcr ≥ 4) is fulfilled. Because of the high drift rate, the residence time of the electrons and protons in the anode–cathode gap is 3–5 ns, while for the C+ carbon ions, it is more than 8 ns. This denotes low efficiency of magnetic self-insulation in a diode of such a design. At the same time, it has been experimentally observed that, during the generation of ion current (second pulse), the electronic component of the total current is suppressed by a factor of 1.5–2 for a strip diode with plane and focusing geometry. A new model of the effect of limiting the electron emission explaining the decrease in the electronic component of the total current in a diode with magnetic self-insulation is proposed.
Unimolecular dissociation of anthracene and acridine cations: The importance of isomerization barriers for the C2H2 loss and HCN loss channels
Authors: Johansson H. A. B. , Zettergren H. , Holm A. I. S. , Haag N. , Nielsen S. Brøndsted , Wyer J. A. , Kirketerp M.-B. S. , Støchkel K. , Hvelplund P. , Schmidt H. T. , Cederquist H.
Published: August 2011

The loss of C2H2 is a low activation energy dissociation channel for anthracene (C14H10) and acridine (C13H9N) cations. For the latter ion another prominent fragmentation pathway is the loss of HCN. We have studied these two dissociation channels by collision induced dissociation experiments of 50 keV anthracene cations and protonated acridine, both produced by electrospray ionization, in collisions with a neutral xenon target. In addition, we have carried out density functional theory calculations on possible reaction pathways for the loss of C2H2 and HCN. The mass spectra display features of multi-step processes, and for protonated acridine the dominant first step process is the loss of a hydrogen from the N site, which then leads to C2H2/HCN loss from the acridine cation. With our calculations we have identified three pathways for the loss of C2H2 from the anthracene cation, with three different cationic products: 2-ethynylnaphthalene, biphenylene, and acenaphthylene. The third product is the one with the overall lowest dissociation energy barrier. For the acridine cation our calculated pathway for the loss of C2H2 leads to the 3-ethynylquinoline cation, and the loss of HCN leads to the biphenylene cation. Isomerization plays an important role in the formation of the non-ethynyl containing products. All calculated fragmentation pathways should be accessible in the present experiment due to substantial energy deposition in the collisions.
Electrostatics and aggregation: How charge can turn a crystal into a gel
Authors: Schmit Jeremy D. , Whitelam Stephen , Dill Ken
Published: August 2011

The crystallization of proteins or colloids is often hindered by the appearance of aggregates of low fractal dimension called gels. Here we study the effect of electrostatics upon crystal and gel formation using an analytic model of hard spheres bearing point charges and short range attractive interactions. We find that the chief electrostatic free energy cost of forming assemblies comes from the entropic loss of counterions that render assemblies charge-neutral. Because there exists more accessible volume for these counterions around an open gel than a dense crystal, there exists an electrostatic entropic driving force favoring the gel over the crystal. This driving force increases with increasing sphere charge, but can be counteracted by increasing counterion concentration. We show that these effects cannot be fully captured by pairwise-additive macroion interactions of the kind often used in simulations, and we show where on the phase diagram to go in order to suppress gel formation.
Uniqueness of steady-state solutions for thermodynamically consistent Becker-Döring models
Authors: Ssemaganda Vincent , Holstein Katharina , Warnecke Gerald
Published: August 2011

Dreyer and Duderstadt [J. Stat. Phys. 123, 1 (2006)]10.1007/s10955-006-9024-z proposed a modification of the standard mass-conserving Becker-Döring model. In this paper we solve for steady-state solutions to two versions of the Becker-Döring model. One is the modified mass-conserving model introduced by Dreyer and Duderstadt. The second one, which is a new version, is a modification of the so called constant free molecule Becker-Döring model. For practical purposes, there is a maximum cluster of size ν allowed in the system. For each version we study the two known truncations to finite system size. One is given by a zero flux to larger cluster sizes out of the system. The second one is obtained by setting the number of clusters larger than ν to zero. For each model and each truncation we determine the unique steady states by studying the null space of the flux matrix. The zero flux truncation gives equilibrium steady-states whereas the zero particle number truncation leads to non-equilibrium steady-states.
Tunneling discharge of positive trapped oxide charge in p-channel field effect transistors
Authors: Kambour K. E. , Kouhestani C. , Nguyen D. , Rosen N. , Devine R. A. B.
Published: August 2011

Negative bias temperature instability has been studied in 130 nm and 90 nm channel length, SiO2 gate insulator field effect transistors at room temperature. Pulsed voltage stressing and subsequent recovery using times starting in the tens of microsecond regime were employed together with a single point data acquisition time ∼4 μs. Threshold voltage shifts were characteristic of oxide charge trapping as opposed to interface state generation. Recovery of the threshold voltage was modeled assuming quantum mechanical tunneling of trapped charges from the dielectric to the Si substrate.
The energy band alignment of Si nanocrystals in SiO2
Authors: Seguini G. , Schamm-Chardon S. , Pellegrino P. , Perego M.
Published: August 2011

The determination of the energy band alignment between the 2.6-nm-diameter Si nanocrystals and the SiO2 host is achieved by means of photo-ionization/-neutralization and capacitance spectroscopy. The measured conduction and valence band offsets are 2.6 eV and 4.4 eV. The band gap is evaluated to be 1.7 eV by photoluminescence. These results indicate that the valence band offset at the Si nanocrystals/SiO2 interface is quite close to the one observed at bulk Si/SiO2 interface. On the contrary, we observe a clear upward shift (0.5 eV) of the conduction band in the Si nanocrystals/SiO2 system with respect to the bulk Si/SiO2 hetero-structure.
Non-local detection of spin-polarized electrons at room temperature in Co50Fe50/GaAs Schottky tunnel junctions
Authors: Uemura Tetsuya , Akiho Takafumi , Harada Masanobu , Matsuda Ken-ichi , Yamamoto Masafumi
Published: August 2011

A clear spin-valve signal and a Hanle signal were observed in a Co50Fe50/n-GaAs Schottky tunnel junction through a four-terminal non-local geometry. The sign and magnitude of the spin-valve signal were strongly dependent on the bias current, suggesting that the spin polarization at the Co50Fe50/n-GaAs interface had strong energy dependence. A clear spin-valve signal was observed at temperatures up to 290 K. The magnitude of the spin-valve signal monotonically decreased by a factor of 7.9 as the temperature increased from 10 K to 290 K; this factor was significantly smaller than the factors reported for Fe/n-GaAs junctions which range from 35 to 80.
Appropriate seating for medical patients: an audit
Authors: Kuys Suzanne S. , Dolecka Urszula E. , Morrison Carol A.
Published: August 2011

Objective. To determine the number and types of chairs available for patient use; to establish minimum criteria of appropriate chairs; and to assess the suitability of available chairs to seat patients admitted to medical wards. Methods. Audit of chairs available in medical wards in a tertiary referral public hospital was conducted. All chairs relevant to patient use were photographed and counted. An expert panel determined minimum criteria of appropriate seating for older patients from functional, occupational health and safety, ergonomic, infection control and usability viewpoints. The number of chairs meeting the minimum criteria level was recorded and was expressed as a percentage of the number of required chairs (hospitalised patients able to be sat out of bed). Results. A total of 270 chairs of 36 different types were identified. The majority of chairs, 231 (85%), did not meet the minimum criteria. Thirty-nine chairs met the minimum criteria for patients to sit in with 113 (66%) patients unable to sit out of bed. Conclusion. This study identified that there were insufficient appropriate chairs available for patients to sit out of bed in this facility. This has potential implications for functional ability of the patients, particularly for the older person. What is known about the topic? Low levels of activity have previously been reported for older adults hospitalised for an acute illness and early mobilisation of stable hospitalised patients, including sitting out of bed for short periods in the day, is regarded as best practice. Some features, such as arm rests and appropriate seat height, of appropriate chairs suitable for older adults are well-known. However, the compliance of facilities to provide appropriate seating has not been investigated. What does this paper add? We conducted a review of available chairs within a medical division of a tertiary referral public hospital with respect to functional, occupational health and safety, ergonomic, infection control and usability criteria. The majority of available chairs did not meet minimum criteria and approximately two-thirds of patients were unable to sit out of bed due to a lack of appropriate chairs. What are the implications for practitioners? Providing appropriate seating to patients, particularly those who are older, during a hospital admission is an essential component of the rehabilitation and recovery process. It cannot be assumed that chairs available are appropriate and regular audits should be conducted.