bluuebunny/crossref_metadata_2025 huggingface dataset:
Inferring likelihoods and climate system characteristics from climate models and multiple tracers
Authors: Sham Bhat K. , Haran Murali , Olson Roman , Keller Klaus
Published: May 2012

Characterizing the risks of anthropogenic climate change poses considerable statistical challenges. A key problem is how to combine the information contained in large‐scale observational data sets with simulations of Earth system models in a statistically sound and computationally tractable manner. Here, we describe a statistical approach for improving projections of the North Atlantic meridional overturning circulation (AMOC). The AMOC is part of the global ocean conveyor belt circulation and transfers heat between low and high latitudes in the Atlantic basin. The AMOC might collapse in a “tipping point” response to anthropogenic climate forcings. Assessing the risk of an AMOC collapse is of considerable interest because it may result in major impacts on natural and human systems. AMOC projections rely on simulations from complex climate models. One key source of uncertainty in AMOC projections is uncertainty about background ocean vertical diffusivity (Kv), an important model parameter.Kvcannot be directly observed but can be inferred by combining climate model output with observations on the oceans (so‐called tracers). Here, we combine information from multiple tracers, each observed on a spatial grid. Our two‐stage approach emulates the computationally expensive climate model using a flexible hierarchical model to connect the tracers. We then inferKvusing our emulator and the observations via a Bayesian approach, accounting for observation error and model discrepancy. We utilize kernel mixing and matrix identities in our Gaussian process model to considerably reduce the computational burdens imposed by the large data sets. We find that our approach is flexible, reduces identifiability issues, and enables inference aboutKvbased on large data sets. We use the resulting inference aboutKvto improve probabilistic projections of the AMOC. Copyright © 2012 John Wiley & Sons, Ltd.
Adult tree swallow survival on the polychlorinated biphenyl–contaminated Hudson River, New York, USA, between 2006 and 2010
Authors: Custer Christine M. , Custer Thomas W. , Hines James E.
Published: May 2012

The upper Hudson River basin in east central New York, USA, is highly contaminated, primarily with polychlorinated biphenyls (PCBs). Reduced adult survival has been documented in tree swallows (Tachycineta bicolor) at a similarly PCB-contaminated river system in western Massachusetts. The purpose of the present study was to assess whether adult survival of tree swallows was likewise affected in the Hudson River basin. Between 2006 and 2010, a total of 521 female tree swallows were banded, of which 148 were retrapped at least once. The authors used Program MARK and an information theoretic approach to test the hypothesis that PCB contamination reduced annual survival of female tree swallows. The model that best described the processes that generated the capture history data included covariate effects of year and female plumage coloration on survival but not PCB/river. Annual survival rates of brown-plumaged females (mostly one year old) were generally lower (mean phi = 0.39) than those of blue-plumaged females (mean phi = 0.50, one year or older). Poor early spring weather in 2007 was associated with reduced survival in both plumage-color groups compared to later years. Models with the effects of PCB exposure on survival (all ΔAICc values >5.0) received little support. Environ. Toxicol. Chem. 2012; 31: 1788–1792. © 2012 SETAC
Mercury in litterfall and upper soil horizons in forested ecosystems in Vermont, USA
Authors: Juillerat Juliette I. , Ross Donald S. , Bank Michael S.
Published: May 2012

Mercury (Hg) is an atmospheric pollutant that, in forest ecosystems, accumulates in foliage and upper soil horizons. The authors measured soil and litterfall Hg at 15 forest sites (northern hardwood to mixed hardwood/conifer) throughout Vermont, USA, to examine variation among tree species, forest type, and soils. Differences were found among the 12 tree species sampled from at least two sites, with Acer pensylvanicum having significantly greater litterfall total Hg concentration. Senescent leaves had greater Hg concentrations if they originated lower in the canopy or had higher surface:weight ratios. Annual litterfall Hg flux had a wide range, 12.6 to 28.5 µg/m2 (mean, 17.9 µg/m2), not related to forest type. Soil and Hg pools in the Oi horizon (litter layer) were not related to the measured Hg deposition flux in litterfall or to total modeled Hg deposition. Despite having lower Hg concentrations, upper mineral soil (A horizons) had greater Hg pools than organic soil horizons (forest floor) due to greater bulk density. Significant differences were found in Hg concentration and Hg/C ratio among soil horizons but not among forest types. Overall, our findings highlight the importance of site history and the benefits of collecting litterfall and soils simultaneously. Observed differences in forest floor Hg pools were strongly correlated with carbon pools, which appeared to be a function of historic land-use patterns. Environ. Toxicol. Chem. 2012; 31: 1720–1729. © 2012 SETAC
Screening for DSM‐IV‐TR cognitive disorder NOS in Parkinson's disease using the Mattis Dementia Rating Scale
Authors: Pontone Gregory M. , Palanci Justin , Williams James R. , Bassett Susan Spear
Published: May 2012

Objective

This study explores the utility of the Mattis Dementia Rating Scale (MDRS) as a screening tool for the Diagnostic and Statistical Manual for Mental Disorders 4th edition (DSM‐IV‐TR) diagnosis cognitive disorder not otherwise specified (NOS) in Parkinson's disease (PD).

Methods

A total of 125 individuals with PD were diagnosed using DSM‐IV‐TR criteria for cognitive disorder NOS and dementia. Receiver operating characteristics (ROC) tested the discriminant validity of the MDRS, with the clinician's diagnosis serving as the gold standard.

Results

The MDRS ROC curve to discriminate subjects with cognitive disorder NOS from non‐demented subjects had an area under the curve of 0.59 (standard error = 0.08, 95% CI: 0.43–0.74).

Conclusions

The MDRS is not effective for identifying PD patients with cognitive disorder NOS without dementia. Copyright © 2012 John Wiley & Sons, Ltd.
IS THERE EMPIRICAL EVIDENCE FOR DECREASING RETURNS TO SCALE IN A HEALTH CAPITAL MODEL?
Authors: Galama Titus J. , Hullegie Patrick , Meijer Erik , Outcault Sarah
Published: May 2012

We estimate a health investment equation, derived from a health capital model that is an extension of the well‐known Grossman model. Of particular interest is whether the health production function has constant returns to scale, as in the standard Grossman model, or decreasing returns to scale, as in the Ehrlich–Chuma model and extensions thereof. The model with decreasing returns to scale has a number of theoretically and empirically desirable characteristics that the constant returns model does not have. Although our empirical equation does not point‐identify the decreasing returns to scale curvature parameter, it does allow us to test for constant versus decreasing returns to scale. The results are suggestive of decreasing returns and in line with prior estimates from the literature. But when we attempt to control for the endogeneity of health by using instrumental variables, the results become inconclusive. This brings into question the robustness of prior estimates in this literature. Copyright © 2012 John Wiley & Sons, Ltd.
A comparison of adverse impact levels based on top‐down, multisource, and assessment center data: Promoting diversity and reducing legal challenges
Authors: John Bernardin H. , Konopaske Robert , Hagan Christine M.
Published: May 2012

We compared levels of adverse impact (AI) against minorities and women based on three promotional decision methods for 428 associate store managers of a Fortune 500 retailer: top‐down appraisal (TDA), multisource appraisal (MSA), and an assessment center (AC). We found significant effects for race and minority status (favoring whites) but no significant effects for gender across all three methods. Comparisons were analyzed using two definitions of AI (four‐fifths rule and the Fisher Exact Test) with a selection ratio (SR) of .25. No evidence of AI was found against blacks for any of the methods. For Hispanics, AI was found under the four‐fifths rule for the AC. For women, the four‐fifths rule was violated using TDA. Results provide some partial support for the argument that diversity goals are more likely to be met using assessment centers compared to TDA when the preponderance of raters are white men. Our data also suggest that carefully crafted, job‐related, top‐down appraisal, combined with rater training, may be effective in facilitating the promotion of more women and minorities and reducing the probability of legal problems. © 2012 Wiley Periodicals, Inc.
Screening‐oriented recruitment messages: Antecedents and relationships with applicant pool quality
Authors: Dineen Brian R. , Williamson Ian O.
Published: May 2012

The ability of firms to attract qualified job applicants is a critical component of the human resource management process. However, while a large body of research has examined the relationship between firm recruitment practices and applicant pool attributes, very little research has investigated what factors are associated with organizational decision makers' utilization of specific recruitment tactics. We draw on labor economics, sociological, and agency theoretical perspectives to make predictions regarding the use of screening‐oriented recruitment messages in actual web‐based job advertisements. Results suggest that perceptions of labor supply, recruiting firm reputation, and the use of quality‐based compensation incentives are associated with use of screening‐oriented messages, which in turn are associated with applicant pool quality. These findings hold important theoretical insights into the factors shaping firm recruitment activity and provide practical strategic implications for managing firm recruitment objectives. © 2012 Wiley Periodicals, Inc.
Further experience with the local lymph node assay using standard radioactive and nonradioactive cell count measurements
Authors: Kolle Susanne N. , Basketter David , Schrage Arnhild , Gamer Armin O. , van Ravenzwaay Bennard , Landsiedel Robert
Published: May 2012

In a previous study, the predictive capacity of a modified local lymph node assay (LLNA) based on cell counts, the LNCC, was demonstrated to be closely similar to that of the original assay. In addition, a range of substances, including some technical/commercial materials and a range of agrochemical formulations (n = 180) have also been assessed in both methods in parallel. The results in the LNCC and LLNA were generally consistent, with 86% yielding an identical classification outcome. Discordant results were associated with borderline data and were evenly distributed between the two methods. Potency information derived from each method also demonstrated good consistency (n = 101), with 93% of predictions being close. Skin irritation was observed only infrequently and was most commonly associated with positive results; it was not associated with the discordant results. Where different vehicles were used with the same test material, the effect on sensitizing activity was modest, consistent with historical data. Analysis of positive control data indicated that the LNCC and LLNA displayed similar levels of biological variation. When taken in combination with the previously published results on LLNA Performance Standard chemicals, it is concluded that the LNCC provides a viable non‐radioactive alternative to the LLNA for the assessment of substances, including potency predictions, as well as for the evaluation of preparations. Copyright © 2012 John Wiley & Sons, Ltd.
Sonography for appendicitis: Nonvisualization of the appendix is an indication for active clinical observation rather than direct referral for computed tomography
Authors: Stewart Jessica K. , Olcott Eric W. , Jeffrey R. Brooke
Published: May 2012

Purpose.

To determine the prevalence of perforated and nonperforated appendicitis in patients with nonvisualization of the appendix on ultrasound (US) performed for suspected appendicitis, and to evaluate the value of CT in these patients.

Methods.

We analyzed 400 consecutive patients undergoing US for suspected appendicitis. Of these patients, 260 had nonvisualization of the appendix, but otherwise normal scans. We analyzed the clinical outcome in these patients to determine the prevalence of appendicitis, referrals for CT, and the contribution of CT in these patients.

Results.

Of the 400 patients, 140 (35%) had either a normal (80 patients, 25%) or an abnormal appendix (60 patients, 15%); 260 (65%) had nonvisualization of the appendix. Overall 75 patients had appendicitis (18.8%) and 17 (4.3%) had appendicitis with perforation. Of the 260 patients with nonvisualization of the appendix, 14 patients (5.4%) had appendicitis and 2 were perforated (0.8%). The prevalence of perforated and nonperforated appendicitis in this group was significantly lower than the overall group (p < 0.001 and p < 0.01, respectively). Of these 260 patients, 101 patients (38.8%) had CT within 48 hours and 79 (78.2%) had normal scans.

Conclusions.

Patients with nonvisualization of the appendix on US, but otherwise normal scans, are at significantly lower risk for appendicitis, either perforated or nonperforated. Active clinical observation should be considered in these patients, rather than direct referral for CT. © 2012 Wiley Periodicals, Inc. J Clin Ultrasound 40:455–461,2012
Moderate correlation between breath‐holding and CO2 inhalation/hyperventilation methods for transcranial doppler evaluation of cerebral vasoreactivity
Authors: Haussen Diogo C. , Katsnelson Michael , Rodriguez Abiezer , Campo Nelly , Campo‐Bustillo Iszet , Romano Jose G , Koch Sebastian
Published: May 2012

Background.

Both CO2 inhalation followed by hyperventilation and breath‐holding have been utilized to measure cerebral vasomotor reactivity (VMR) but their correlation has been poorly studied and understood.

Methods.

A retrospective study was conducted in 143 subjects (62.6 ± 15.8 years old, 64% men) with transcranial Doppler ultrasonography measurement of mean flow velocity (MFV) at baseline, after 30 seconds of breath‐holding, and after CO2 inhalation followed by hyperventilation, in the left and right middle cerebral artery. Breath‐holding index (BHI) was calculated as the percentage of MFV increase from baseline per second of apnea. CO2 inhalation/hyperventilation index (CO2/HV) was calculated as the percentage of MFV difference between CO2 inhalation and hyperventilation.

Results.

There were 75 carotid arteries with >70% stenosis or occlusion, and 18 middle cerebral arteries with >50% stenosis or occlusion. The mean BHI was 0.93 ± 0.7 and 0.89 ± 0.6, whereas the mean CO2/HV was 61 ± 26% and 60 ± 26%, respectively, on the right and left sides. The correlation between BHI and CO2/HV was moderate on the right (r = 0.33; p < 0.01) and left sides (r = 0.38; p < 0.01). Multivariate linear regression analysis indicated that age (p = 0.01) and history of stroke (p = 0.007) were associated independently with an impaired VMR on the right as measured by CO2/HV. No predictors for impaired VMR by CO2/HV on the left and by BHI on either side were found.

Conclusions.

CO2/HV and BHI are only moderately correlated. Further studies are necessary to determine which method more accurately predicts clinical morbidity. © 2012 Wiley Periodicals, Inc. J Clin Ultrasound 2012; Published online in Wiley Online Library
Phonon anomalies and structural transition in spin ice Dy2Ti2O7: a simultaneous pressure‐dependent and temperature‐dependent Raman study
Authors: Saha Surajit , Ghalsasi Pallavi , Muthu D. V. S. , Singh Surjeet , Suryanarayanan R. , Revcolevschi A. , Sood A. K.
Published: May 2012

We revisit the assignment of Raman phonons of rare‐earth titanates by performing Raman measurements on single crystals of O18 isotope‐rich spin ice and nonmagnetic pyrochlores and compare the results with their O16 counterparts. We show that the low‐wavenumber Raman modes below 250 cm−1 are not due to oxygen vibrations. A mode near 200 cm−1, commonly assigned as F2g phonon, which shows highly anomalous temperature dependence, is now assigned to a disorder‐induced Raman active mode involving Ti4+ vibrations. Moreover, we address here the origin of the ‘new’ Raman mode, observed below TC ~ 110 K in Dy2Ti2O7, through a simultaneous pressure‐dependent and temperature‐dependent Raman study. Our study confirms the ‘new’ mode to be a phonon mode. We find that dTC/dP = + 5.9 K/GPa. Temperature dependence of other phonons has also been studied at various pressures up to ~8 GPa. We find that pressure suppresses the anomalous temperature dependence. The role of the inherent vacant sites present in the pyrochlore structure in the anomalous temperature dependence is also discussed. Copyright © 2012 John Wiley & Sons, Ltd.
Adaptation to potassium starvation of wild‐type and K+‐transport mutant (trk1,2) of Saccharomyces cerevisiae: 2‐dimensional gel electrophoresis‐based proteomic approach
Authors: Gelis Samuel , Curto Miguel , Valledor Luis , González Asier , Ariño Joaquín , Jorrín Jesús , Ramos José
Published: May 2012

Saccharomyces cerevisiae wild‐type (BY4741) and the corresponding mutant lacking the plasma membrane main potassium uptake systems (trk1,trk2) were used to analyze the consequences of K+ starvation following a proteomic approach. In order to trigger high‐affinity mode of potassium transport, cells were transferred to potassium‐free medium. Protein profile was followed by two‐dimensional (2‐D) gels in samples taken at 0, 30, 60, 120, 180, and 300 min during starvation. We observed a general decrease of protein content during starvation that was especially drastic in the mutant strain as it was the case of an important number of proteins involved in glycolysis. On the contrary, we identified proteins related to stress response and alternative energetic metabolism that remained clearly present. Neural network‐based analysis indicated that wild type was able to adapt much faster than the mutant to the stress process. We conclude that complete potassium starvation is a stressful process for yeast cells, especially for potassium transport mutants, and we propose that less stressing conditions should be used in order to study potassium homeostasis in yeast.
Charge carrier mobility, photovoltaic, and electroluminescent properties of anthracene‐based conjugated polymers bearing randomly distributed side chains
Authors: Usluer Özlem , Kästner Christian , Abbas Mamatimin , Ulbricht Christoph , Cimrova Vera , Wild Andreas , Birckner Eckhard , Tekin Nalan , Sariciftci Niyazi Serdar , Hoppe Harald , Rathgeber Silke , Egbe Daniel A. M.
Published: May 2012

This article reports on the synthesis, characterization, and properties of various anthracene‐containing poly (p‐phenylene‐ethynylene)‐alt‐poly(p‐phenylene‐vinylene) (PPE‐PPV) polymers (AnE‐PVs) bearing statistical distributions of various side chains. Primarily, the ratio of linear octyloxy and branched 2‐ethylhexyloxy side chains at the poly(p‐phenylene vinylene) (PPV) parts was varied, leading to the polymers stat, stat1, and stat2. Furthermore, polymers also containing asymmetric substituted PPV and poly(p‐phenylene ethynylene) units (bearing methoxy and 2‐ethylhexyloxy side chains) were prepared yielding stat3, stat4, and stat5. These materials exhibit a broad variation in their photovoltaic properties. It is once more shown that side chains and their distribution can crucially affect the photovoltaic device performance. The introduction of units with asymmetric substitution into these systems seems to be harmful for their utilization in photovoltaic applications. Organic field‐effect transistors were fabricated to investigate hole mobilities in these new materials. Large variance was observed, falling in the range of almost two orders of magnitude, indicating rather different π–π stacking behavior of the polymer backbones owing to side‐chain modifications. Moreover, a selection of the new polymeric systems was investigated regarding their potential for light‐emitting diode (LED) applications. Polymer LEDs using the polymers AnE‐PVstat, ‐stat3, ‐stat4, and ‐stat5, as the active layer showed turn‐on voltage of ∼2 V and exhibited red light emission. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Thermally induced fixed diradical generation on solid supports for surface‐initiated polymerization
Authors: Gure Baris , Bicak Niyazi
Published: May 2012

A method is presented for generation of all surface‐bound radicals on solid polymer surfaces. Thus, secondary amide group of newly synthesized crosslinking comonomer, methacryloyloxyethyl methacrylamide was determined as versatile precursor for generation fixed diradicals on solid microspheres, obtained by copolymerization with methyl methacrylate (MMA) in aqueous suspension. Nitrosoation of the secondary amide groups on the microbeads and followed thermolysis above 90 °C was demonstrated to give surface‐bound radicals, capable of initiating polymerization of vinyl monomers, such as; styrene, MMA, N‐vinyl formamide, and N‐vinyl, 2‐pyrrolidone, as evidenced by H NMR, Fourier transform infrared, thermogravimetric analysis, and differential scanning calorimeter techniques. Appreciable grafting yields (55.1%–286.1%) and low free‐homopolymer formation (7.2%–19.7%) were noted within 6 h of the grafting at 100 °C in each case. This strategy involving the use of amide functional crosslinker seemed to be generally applicable to generate surface‐bound radicals for surface‐initiated polymerization from various solid substrates. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Porphyrin derivatives act as vinylene monomers in TEMPO‐mediated radical copolymerization with styrene
Authors: Obata Makoto , Ohtake Eiko , Hirohara Shiho , Tanihara Masao , Yano Shigenobu
Published: May 2012

In this article, we offer clear evidence for the radical copolymerizability of porphyrin rings in 2,2,6,6‐tetramethyl‐1‐piperidinyloxy (TEMPO)‐mediated radical copolymerizations with styrene. The radical copolymerizations of styrene with 5,10,15,20‐tetrakis(pentafluorophenyl)porphyrin (H2TFPP) was conducted using 1‐phenyl‐1‐(2,2,6,6‐tetramethyl‐1‐piperidinyloxy)ethane as an initiator. The refractive index (RI) traces for the size‐exclusion chromatography of the resulting copolymers were unimodal with narrow molecular weight distributions. The RI traces shifted toward higher molecular weight regions as the polymerization progressed, and the number‐average molecular weights were close to those calculated on the basis of the feed compositions and monomer conversions. These features were in good agreement with a TEMPO‐mediated mechanism. The traces recorded by the ultraviolet‐visible (UV‐vis) detector (430 nm) were identical to those obtained by the RI detector, indicating a statistical copolymerization of styrene with H2TFPP. This also indicated that H2TFPP acted as a monomer and not as a terminator or a chain‐transfer agent under the conditions used. A benzyl radical addition to H2TFPP was conducted as a model reaction for the copolymerization using tributyltin hydride as a chain‐transfer agent, affording a reduced porphyrin, 2‐benzyl‐5,10,15,20‐tetrakis(pentafluorophenyl)chlorin 1, via radical addition to the β‐pyrrole position. The UV‐vis spectrum of 1 was fairly similar to that of poly(styrene‐co‐H2TFPP), indicating that H2TFPP polymerized at its β‐pyrrole position in the TEMPO‐mediated radical polymerization. TEMPO‐mediated radical copolymerizations of styrene with several porphyrin derivatives were also demonstrated. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Influence of the graphite type on the synthesis of polypropylene/graphene nanocomposites
Authors: Milani Marcéo A. , Quijada Raul , Basso Nara R. S. , Graebin Ana P. , Galland Griselda B.
Published: May 2012

In this work, the synthesis of polypropylene (PP)/graphene nanosheet (GNS) nanocomposites by in situ polymerization using metallocene catalysts was studied. Initial reactions were performed using rac‐Et(Ind)2ZrCl2 and rac‐Me2Si(Ind)2ZrCl2 catalysts to select the best one to obtain good molecular weight, thermal properties, and tacticity. Subsequently, PP nanocomposites with different loadings of GNS were obtained. GNS from two different sources [Graphite Nacional (GN) and Graphite Aldrich (GA)] have been used, and the differences between the obtained nanocomposites were evaluated. The GNS and nanocomposites were studied by scanning electronic microcopy, transmission electronic microcopy, and X‐ray diffraction. They showed that the GN nanosheets had lower crystal size and diameter than the GA nanosheets and dispersed better in the PP matrix. Differential scanning calorimetry analyses of both types of nanocomposites showed an increase in the crystallization temperature with increasing graphite loading. The polymeric materials were also characterized by GPC, thermogravimetric analysis, and 13C NMR. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Well‐defined amphiphilic polymethylene‐b‐poly(acrylic acid) diblock copolymers: New synthetic strategy and their self‐assembly
Authors: Lu Hui‐Chao , Xue Yang , Zhao Qiao‐Ling , Huang Jin , Xu Shen‐Gang , Cao Shao‐Kui , Ma Zhi
Published: May 2012

Well‐defined amphiphilic polymethylene‐b‐poly (acrylicacid) diblock copolymers have been synthesized via a new strategy combining polyhomologation and atom transfer radical polymerization (ATRP). Hydroxyl‐terminated polymethylenes (PM‐OH) with different molecular weights and narrow molecular weight distribution are obtained through the polyhomologation of dimethylsulfoxonium methylides following quantitative oxidation via trimethylamine‐N‐oxide dihydrate. Subsequently, polymethylene‐based macroinitiators (PM‐MIs Mn = 1,300 g mol−1 [Mw/Mn = 1.11] and Mn = 3,300 g mol−1 [Mw/Mn = 1.04]) are synthesized by transformation of terminal hydroxyl group of PM‐OH to α‐haloester in ∼100% conversion. ATRPs of tert‐butyl acrylate (t‐BuA) are then carried out using PM‐MIs as initiator to construct PM‐b‐P(t‐BuA) diblock copolymers with controllable molecular weight (Mn = 8,800–15,800 g mol−1
Mw/Mn = 1.04–1.09) and different weight ratio of PM/P(t‐BuA) segment (1:1.7–1:11.2). The amphiphilic PM‐b‐PAA diblock copolymers are finally prepared by hydrolysis of PM‐b‐P(t‐BuA) copolymers and their self‐assembly behavior in water is preliminarily investigated via the determination of critical micelle concentrations, dynamic light scattering, and transmission electron microscope (TEM). © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Dynamic mechanical properties of polystyrene ionomers containing both carboxylate and sulfonate anionic groups
Authors: Song Ju‐Myung , Ko Kwang‐Hwan , Kim Joon‐Seop , Shin Kwanwoo
Published: May 2012

Polystyrene‐based ionomers possessing sodium methacrylate (MA) and sodium styrenesulfonate (SS) units in each polymer chain [poly(styrene‐co‐methacrylate‐co‐styrenesulfonate) (PSMA‐SS)] were synthesized. The dynamic mechanical properties of PSMA‐SS ionomers were studied and compared with those of styrene ionomers containing only MA (PSMA ionomer) or SS (PSS ionomer) units. It was observed that the ionic moduli of PSMA‐SS ionomers depended directly on the total ion content and that the ionic modulus was highest for the PSMA ionomer and lowest for the PSMA‐SS ionomer. The matrix Tgs of the three ionomer systems were found to be similar to each other; the cluster Tg of PSMA‐SS ionomer was higher than that of PSS ionomer at low SS contents but became closer to each other at high SS contents. In addition, the small‐angle X‐ray scattering study revealed that the multiplet size might be in the following order: PSMA‐SS > PSS > PSMA. This implied that at the same ion content, the fractions of cluster regions were smallest for PSMA‐SS ionomer in comparison with those of PSS or PSMA ionomers. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012
Dimeric analogs of immunosuppressive decapeptide fragment of ubiquitin
Authors: Kluczyk Alicja , Cydzik Marzena , Biernat Monika , Bąchor Remigiusz , Pasikowski Paweł , Stefanowicz Piotr , Artym Jolanta , Zimecki Michał , Szewczuk Zbigniew
Published: May 2012

Our previous studies revealed that ubiquitin and its decapeptide fragment with the LEDGRTLSDY sequence, located on the exposed molecule loop, strongly suppressed the immune response. This suggested that the loop may serve as a functional epitope of ubiquitin molecule and that a possible mechanism of biological action of the synthesized peptides is associated with interfering in interactions of ubiquitin with other molecules. Ubiquitin is known to exist in oligomeric forms, which can interact with various oligomeric receptors. We designed and synthesized new dimeric analogs of the ubiquitin fragment, to probe whether dimeric peptides may have higher affinity towards the ubiquitin receptors responsible for immunosuppression, which are believed to form oligomeric structures. Three dimerization strategies, N‐terminus to N‐terminus, C‐terminus to C‐terminus, and N‐terminus to C‐terminus (head‐to‐tail) via PEG derivatives were used to synthesize the dimeric peptides on solid support. In the course of our research, we developed a new and straightforward procedure of dimerization where α‐amino groups of the C‐terminal lysine residues of two peptide fragments were linked by PEG spacer directly on solid support.

The effect of dimeric analogs on the immunological response was tested in the AFC in vitro experiment. The immunological tests showed that the head‐to‐tail dimerization caused a more profound increase in the biological activity than other tested dimerization methods. Our results suggest that such orientation of peptide components may correspond to orientation of the hypothetic ubiquitin receptors responsible for the immunomodulatory activity. Copyright © 2012 European Peptide Society and John Wiley & Sons, Ltd.
Luminescence studies of isolated ZnO nanowires grown by the vapour‐liquid‐solid method
Authors: Martínez Oscar , Güell Frank , Hortelano Vanesa , Jiménez Juan , Cornet Albert , Morante Joan Ramon
Published: May 2012

In this work we analysed, by means of Spectral Imaging Cathodoluminescence, the luminescence properties of individual ZnO nanowires (NWs) grown by chemical vapour deposition. The NWs show a general increase of the radiative recombination channels, and a decrease of the relative intensity of the visible band respect to the bound exciton emission, pointing to a high crystal quality. Local changes in the peak position and intensity of the near band edge were found by studying the luminescence of individual NWs, which have been ascribed to structural changes along them (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High sensitivity hydrogen sensors based on GaN
Authors: Yatskiv Roman , Grym Jan , Zdansky Karel
Published: May 2012

High quality graphite based Schottky diodes are presented. Schottky barriers were prepared by mechanical deposition of colloidal graphite on GaN substrates uncoverd and partly covered with Pt nanoparticles deposited by electrophoretic techniques. The electron transport for both diodes can be well described by thermionic emission. Hydrogen sensing characteristics of graphite‐Pt/GaN Schottky diodes were investigated. Temperature dependence of the sensitivity, the barrier height variation, the ideality factor and the barrier height itself were studied. The proposed hydrogen sensor responds well to various hydrogen containing gases. The room‐temperature sensitivity response of 2x107 was obtained in 1000 ppm H2/N2ambient. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Emission and elastic strain in InGaAs/GaAs quantum wells with embedded InAs quantum dots
Authors: Vega‐Macotela L. G. , Polupan G. , Shcherbyna Ye.
Published: May 2012

Photoluminescence (PL) spectra have been studied in the symmetric GaAs/In0.15Ga0.85As/GaAs quantum wells (QWs) with embedded InAs quantum dots (QDs), grown at different temperatures from the range 470‐535 °C. The increase of QD growth temperature is accompanied by decreasing the QD surface density and the enlargement of QD lateral diameters. Simultaneously the variation of the PL intensity and PL peak positions none monotonously have been detected. To understand the reason of the variation of PL intensity and peak positions the PL temperature dependences and the X‐ray diffraction (XRD) at low angles (1.75‐1.92°) have been studied. The fitting procedure is applied to analysis the temperature shift of PL peak positions. Fitting has been done on the base of empirical expression for the band gap shrinkage that uses the Einstein temperature parameter. The character non monotonous for the Ga/In inter diffusion versus QD growth temperatures has been revealed. The XRD study has detected the high intensity peaks that corresponds to the diffraction of X‐ray beam from the (311) crystal planes in GaAs QWs. The position of XRD peaks in the structures with QD grown at 490‐510 °C is very close to the angles related to the diffraction from (311) planes in the bulk GaAs. In QD structures with QD grown at 470 and 525‐535 °C the (311) XRD peaks shift to the higher diffraction angles that testifies on the essential compressive strains in these structures. The reason of the variation non monotonously of elastic strain versus QD densities has been discussed (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Characterization of InAs/GaSb type‐II superlattice photodiodes for mid‐wave IR with different mesa sidewall passivation schemes
Authors: Karim Amir , Marcks von Würtemberg Rickard , Asplund Carl , Malm Hedda , Andersson Jan , Plis Elena , Krishna Sanjay
Published: May 2012

We report on the electrical and material characterization of InAs/GaSb type‐II superlattice (T2SL) mid‐wave infrared (MWIR) photodiodes with different passivation schemes on the mesa‐sidewalls with significant differences in the resulting low temperature dark currents. Devices fabricated by dry etching and passivated with polymerized photoresist, show orders of magnitude lower dark currents as compared to unpassivated devices. The mesa side walls were examined using high resolution transmission electron microscopy (HRTEM) with a special focus on the interface between the superlattice material and the dielectric passivation. Material analysis on nanometer scale at the mesa sidewall interface was performed using energy dispersive X‐ray (EDX) spectrometry. EDX line scans were obtained from interfaces for different passivated and unpassivated devices, using the highly focused electron beam in TEM, to investigate the chemical compositions. The unpassivated and photoresist‐passivated mesas, with different electrical properties, revealed different sidewall morphologies and compositions. An oxygen containing layer was observed in photoresist‐passivated devices covering the whole mesa sidewall. We think this plays a role in reducing surface leakage dark current. In HR‐TEM the mesa sidewall topography reveals preferential etching of one superlattice component as previously observed. Nevertheless, the dielectric material covers the sidewall uniformly (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Irradiation induced nanotrack and property modification in Zn3P2
Authors: Sudhakar Selvakumar , Nagarajan Mony , Baskar Krishnan
Published: May 2012

Zn3P2 epilayers were grown on InP (100) substrates by liquid phase epitaxy (LPE) using In solvent. Zinc composition in the epilayers was varied by changing the zinc mole fraction in the growth melt and was confirmed by energy dispersive X‐ray analysis (EDAX). Stoichiometric Zn3P2 epilayers were subjected to 100 MeV Ni ion irradiation with various ion fluences of 1 × 1010 to 1 × 1013 ions/cm2 at 77 K. From the high resolution X‐ray diffraction (HRXRD) of 100 MeV Ni ion irradiated epilayers, the decrease in the peak intensities and increase in the FWHM values were observed. AFM analysis revealed the formation of nanotracks in the irradiated Zn3P2 epilayers. Hall measurements showed the decrease in carrier mobility with the increase of ion fluence. The absorption band edge of Zn3P2 gradually decreased from 1.49 eV to 1.42 eV upon increasing the ion fluence (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Lösungen für energieeffiziente multifunktionale Verglasungen
Authors: Schneider Frank
Published: May 2012

Die Glasfassade muss heute Aufgaben übernehmen, die längst über die ursprüngliche Anwendung als wärmedämmender Raumabschluss hinausgehen. Insbesondere der sommerliche Überhitzungsschutz spielt eine entscheidende Rolle. Intelligent gestaltete Glasfassaden sind aber durchaus in der Lage den Energieverbrauch eines Gebäudes positiv zu reduzieren und den Nutzungskomfort zu verbessern. Zunächst soll auf die grundlegenden bauphysikalischen Parameter eingegangen werden, die ein Isolierglas charakterisieren. Anschließend werden anhand von Beispielen Lösungen für multifunktionale Gebäudehüllen aus Glas aufgezeigt.
Computational methods for climate data
Authors: El‐Askary Hesham , Allali Mohamed , Rakovski Cyril , Prasad Anup , Kafatos Menas , Struppa Daniele
Published: May 2012

As climate changes, regional responses may become more apparent; impacts often can become natural hazards, adversely affecting millions of people, on all continents and most nations. The coupling of hazards to climate change scenarios is a great challenge of climate change science. Nevertheless, it is extremely important to observe, simulate and ultimately understand this coupling, for the benefit of society and sustainability of the Earth's environment. Different applied mathematical techniques have been used to discern real effects of these changes and study long term trends. Moreover, those techniques can be applied in addressing the intensity and frequency of extreme events associated with climate change at regional scales and would be an important step in facing future extreme events associated with climate change. Computational methods include applying statistical data analysis, mesoscale and climate simulations while assisting modeling efforts with satellite based observations. Predictive analytics platforms would be very useful for assessing impacts of climate variability and change on the frequency and intensity of extreme events and how these extreme events can affect water and air quality issues globally. These tools are an innovative technology that applies data mining methods, predictive models, analysis and reporting to data, without the inherent limitations of current On Line Analytical Processing tools that suffer from cube rigidity, database explosion and dimensional constriction. Climate‐induced changes are complex and vary across a wide range of dimensions. An important part of predictive analytics platforms are their unlimited dimensionality and the segmentation of data by ‘physical’ or ‘performance’ characteristics. For example, a physical dimension might be the climate divisions in the state of California. A performance dimension could be the arithmetical, mathematical, or statistical segmentation of data based on its performance with regard to time.WIREs Comput Stat2012 doi: 10.1002/wics.1213

This article is categorized under:

Applications of Computational Statistics > Computational Climate Change and Numerical Weather Forecasting

Applications of Computational Statistics > Signal and Image Processing and Coding

Data: Types and Structure > Time Series, Stochastic Processes, and Functional Data
Visual acuity of dentists under simulated clinical conditions
Authors: Eichenberger Martina , Perrin Philippe , Neuhaus Klaus W. , Bringolf Ueli , Lussi Adrian
Published: May 2012

Objectives

This study examined the near visual acuity of dentists in relation to age and magnification under simulated clinical conditions.

Materials and methods

Miniaturized visual tests were performed in posterior teeth of a dental phantom head in a simulated clinical setting (dental chair, operating lamp, dental mirror). The visual acuity of 40 dentists was measured under the following conditions: (1) natural visual acuity, distance of 300 mm; (2) natural visual acuity, free choice of distance; (3) Galilean loupes, magnification of ×2.5; (4) Keplerian loupes, ×4.3; (5) operating microscope, ×4, integrated light; (6) operating microscope, ×6.4, integrated light.

Results

The visual acuity varied widely between individuals and was significantly lower in the group ≥40 years of age (p < 0.001). Significant differences were found between all tested conditions (p < 0.01). Furthermore, a correlation between visual acuity and age was found for all conditions. The performance with the microscope was better than with loupes even with comparable magnification factors. Some dentists had a better visual acuity without optical aids than others with Galilean loupes.

Conclusions

Near visual acuity under simulated clinical conditions varies widely between individuals and decreases throughout life. Visual deficiencies can be compensated for with optical aids.

Clinical relevance

Newly developed miniaturized vision tests have allowed, in a clinically relevant way, to evaluate the influence of magnification and age on the near visual acuity of dentists.
The Circulating Nurse's Role in Error Recovery in the Cardiovascular OR
Authors: Yang Y. Tony , Henry Linda , Dellinger Mary , Yonish Kersten , Emerson Brett , Seifert Patricia C.
Published: May 2012

Nursing surveillance, an essential component of perioperative practice, includes the detection of and recovery from errors. However, error recovery is considered routine during nursing care and may go under‐recognized. This study assessed the types of errors or potential errors that were detected and recovered by the circulating nurse during care of patients undergoing coronary artery or valve surgery. From June to September 2010, perioperative nurses observed 18 surgical procedures. An average of 11.11 errors or incidents occurred per procedure; however, 77% of all incidents were intercepted and the other 23% were either mitigated or ameliorated so no adverse outcomes occurred. This study demonstrates that nurses play an important role in ensuring patient safety and reinforces the necessity of vigilance in the OR, especially in regard to aseptic technique and surgical prepping.
Leptospirosis following a major flood in Central Queensland, Australia
Authors: SMITH J. K. G. , YOUNG M. M. , WILSON K. L. , CRAIG S. B.
Published: May 2012

Throughout December 2010 and January 2011, Queensland experienced widespread flooding due to unusually protracted and heavy rainfalls. In mid-January 2011, four individuals from a small community in Central Queensland were hospitalized with leptospirosis. A further five cases were subsequently identified from around Central Queensland, bringing the total to nine. Microscopic agglutination testing found that serovar Arborea (Leptospira borgpetersenii serovar Arborea) was presumptively responsible for leptospirosis in seven of nine confirmed cases. Serovars Hardjo and Australis were identified in samples from two remaining cases. All cases had exposure to flood water. No single exposure source was identified. This is the first reported outbreak of leptospirosis in Central Queensland and the first report of leptospirosis cases associated with flood water inundation in Queensland. Public health authorities should continue to promote awareness of leptospirosis in flood-affected populations. Healthcare providers must maintain a high level of suspicion for leptospirosis during and after flood events.
Infant feeding in relation to eating patterns in the second year of life and weight status in the fourth year
Authors: Abraham Elizheeba C , Godwin Jon , Sherriff Andrea , Armstrong Julie
Published: May 2012

Objective

To explore associations of early infant feeding with (i) eating patterns in the second year of life and (ii) weight status in the fourth year of life in a prospective cohort of children in Scotland.

Design

Growing Up in Scotland (GUS) longitudinal birth cohort study (2005–2008).

Setting

Scotland, UK.

Subjects

Children aged 9–12 months (n 5217) followed through to 45–48 months.

Results

Infant feeding was associated with eating patterns, defined by using SPSS two-step cluster analysis, in the second year of life. Children who were ever breast-fed compared with never breast-fed (adjusted OR = 1·48, 95 % CI 1·27, 1·73) were more likely to have a positive eating pattern (Cluster 2). Children who started complementary feeding at 4–5 months or 6–10 months compared with 0–3 months (adjusted OR = 1·32, 95 % CI 1·09, 1·59 or AOR = 1·50, 95 % CI 1·19, 1·89) were more likely to belong to Cluster 2. Breast-feeding was negatively associated with being overweight or obese in the fourth year of life compared with no breast-feeding (adjusted OR = 0·81, 95 % CI 0·81, 1·01). Introduction of complementary feeding at 4–5 months compared with 0–3 months was negatively associated with being overweight or obese (adjusted OR = 0·74, 95 % CI 0·57, 0·97).

Conclusions

Breast-feeding and introduction of complementary feeding after 4 months were associated with a positive eating pattern in the second year of life. Introduction of complementary feeding at 4–5 months compared with 0–3 months was negatively associated with being overweight or obese.
The Political Science of Genocide: Outlines of an Emerging Research Agenda
Authors: Verdeja Ernesto
Published: May 2012

Over the past two decades, scholars have generated a large and sophisticated literature on genocide. Nevertheless, there are still several research areas that require further work. This article outlines a research agenda that analyzes the conditions under which genocide is likely to occur, the multilevel processes of violent escalation and de-escalation, and the ways in which these processes are shaped by, connect to, reinforce, accelerate and impede one another. I argue that scholars should 1) model elite and follower radicalization processes by disaggregating genocidal “intent” over time and space, and exploring how intent emerges rather than taking it as pre-given. Doing so will permit researchers to 2) situate genocide research within a broader context of political violence in order to understand how they are related temporally and spatially, and to decenter analytical domains beyond the standard country level and single victim group in order to gain insight into the dynamics of genocide, including how perpetrator policies vary by group; 3) draw on recent advances in microanalyses of civil war to theorize about subnational patterns of violence diffusion; 4) move beyond problematic contrasts between ideology and rationality to analyze how ideologies frame the strategic choices “available” to genocidal elites.
Genocide and the Psychology of Perpetrators, Bystanders, and Victims
Authors: Fujii Lee Ann
Published: May 2012

We live in a world laced with forms of political violence. Kristen Renwick Monroe's latest work develops an interesting social psychological account of the conduct of victims, perpetrators, and bystanders of the most extreme form of violence—genocide. It also employs an interesting narrative approach that contributes to broad methodological discussions in political science about the ways in which subjective experience can best be understood. We have thus invited a diverse group of political scientists and historians to comment on the book's analysis of political violence and on its broader approach to the study of politics.—Jeffrey C. Isaac, Editor