bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of vagus nerve stimulation during transient focal cerebral ischemia on chronic outcome in rats
Authors: Hiraki Teruyuki , Baker Wesley , Greenberg Joel H.
Published: December 2011

The aim of this study was to investigate the effect of vagus nerve stimulation (VNS) on infarct volume and neurological recovery up to 3 weeks following transient focal cerebral ischemia. Transient ischemia was produced by filament occlusion of the proximal middle cerebral artery (MCA) in rats. The right vagus nerve was stimulated starting 30 min after MCA occlusion and consisted of 30‐sec pulse trains (20 Hz) delivered to the animal's right vagus nerve every 5 min for a total period of 60 min (n = 10). All the procedures were duplicated, but no stimulus was delivered, in a control group (n = 10). Neurological evaluations were performed in all animals at 24 hr, 48 hr, 1 week, 2 weeks, and 3 weeks after MCA occlusion; animals were euthanized; and neuronal damage was evaluated in hematoxylin‐eosin‐stained sections. The ischemic lesion volume was smaller in the VNS‐treated animals in comparison with the nonstimulated group (P < 0.02). Although the functional score in both treated and untreated groups improved over the 3‐week observation period (P < 0.001), there was still a statistically significant improvement reszulting from VNS treatment compared with control animals (P < 0.05). Cerebral blood flow changes in the MCA territory during ischemia did not differ between the VNS‐treated animals (31.9% ± 10.4% of baseline) and control animals (29.9% ± 9.1%; P = 0.6). Stimulation of the vagus nerve for only a brief period early in ischemia provides neuroprotection in transient ischemia, with neuroprotection persisting for at least 3 weeks. © 2011 Wiley Periodicals, Inc.
Osteopontin is an alpha motor neuron marker in the mouse spinal cord
Authors: Misawa Hidemi , Hara Mayumi , Tanabe Shogo , Niikura Mamiko , Moriwaki Yasuhiro , Okuda Takashi
Published: December 2011

Motor neurons (MNs) are designated as alpha/gamma and fast/slow based on their target sites and the types of muscle fibers innervated; however, few molecular markers that distinguish between these subtypes are available. Here we report that osteopontin (OPN) is a selective marker of alpha MNs in the mouse spinal cord. OPN was detected in approximately 70% of postnatal choline acetyltransferase (ChAT)‐positive MNs with relatively large somas, but not in those with smaller somas. OPN+/ChAT+ MNs were also positive for NeuN, an alpha MN marker, but were negative for Err3, a gamma MN marker. The size distribution of OPN+/ChAT+ cells was nearly identical to that of NeuN+/ChAT+ alpha MNs. Group Ia proprioceptive terminals immunoreactive for vesicular glutamate transporter‐1 were selectively detected on the OPN+/ChAT+ cells. OPN staining was also detected at motor axon terminals at neuromuscular junctions, where the OPN+ terminals were positive or negative for SV2A, a marker distinguishing fast/slow motor endplates. Finally, retrograde labeling following intramuscular injection of fast blue indicated that OPN is expressed in both fast and slow MNs. Collectively, our findings show that OPN is an alpha MN marker present in both the soma and the endplates of alpha MNs in the postnatal mouse spinal cord. © 2011 Wiley Periodicals, Inc.
Power of teleconnection patterns on precipitation and streamflow variability of upper Medjerda Basin
Authors: Ouachani Rim , Bargaoui Zoubeida , Ouarda Taha
Published: December 2011

The potential impact of large‐scale climate patterns of El Niño Southern Oscillation (ENSO), North Atlantic Oscillation (NAO) and Pacific Decadal Oscillation (PDO) in modulating precipitation regimes across the upper Medjerda River Basin in northern Tunisia is assessed. As the case study is located in the Mediterranean region (North Africa), the regional Mediterranean Oscillation (MOAC) and Western Mediterranean Oscillation (WeMO) are also investigated. Six precipitation time series are also observed. Strong correlations are identified between ENSO and precipitation series at lag − 2 years. Extreme ENSO years are reflected in the precipitation as periods of severe water deficit or excess. Wavelet spectra driven to seasonal precipitation reveal that precipitation is organized in preferred bands with distinct activities in each scale band, and that most of the precipitation variance is explained by the 2–8‐year scales. Using cross‐wavelet analysis, climate patterns that are most associated with precipitation variability are identified. The analysis demonstrates also that precipitations are simultaneously controlled by different climate patterns. Particularly, the influence of ENSO on precipitation is stronger as well as that of PDO and MO. Results indicate that precipitation variability at the upper Medjerda River Basin is associated with global‐scale ENSO processes at the annual as well as seasonal time scales and is aligned with changing phase difference between periods. Moreover, separation of annual precipitation into two seasons reveals statistically significant associations between El Niño and La Niña phases of ENSO with dry and wet seasonal precipitation, respectively. Complementing this, three streamflow records with length up to 104 years are used, and relationships with rainfall series are analysed using wavelets. A strong coherence between rainfall and streamflow observations is found and justifies undertaking the study of climate‐streamflow relationships where ENSO exhibits potential impacts on annual streamflows. Copyright © 2011 Royal Meteorological Society
Generation of bounded semigroups in nonlinear subsonic flow–structure interactions with boundary dissipation
Authors: Lasiecka Irena , Webster Justin
Published: December 2011

We consider a subsonic flow–structure interaction describing the flow of gas above a flexible plate. A perturbed wave equation describes the flow, and a second‐order nonlinear plate equation describes the plate's displacement. We consider the model that accounts for rotational inertia in the plate, parametrized by γ  ≥ 0. It is known that the presence of γ  >  0 has strong effect on regularity properties of the plate, which then allows one to establish well‐posedness of finite energy solutions for the entire structure. In this paper, it is shown that semigroup well‐posedness of the model is not only preserved for all γ  ≥ 0 but that the corresponding nonlinear semigroups Sγ(t) converge to S0(t) when γ  → 0. The above result holds also in the presence of nonlinear boundary damping. In addition, we provide a discussion of the regularity of strong solutions. Copyright © 2011 John Wiley & Sons, Ltd.
Adaptive Fourier decomposition of functions in quaternionic Hardy spaces
Authors: Qian Tao , Sprößig Wolfgang , Wang Jinxun
Published: December 2011

We study decompositions of functions in the Hardy spaces into linear combinations of the basic functions in the orthogonal rational systems Bn, which are obtained in the respective contexts through Gram–Schmidt orthogonalization process on shifted Cauchy kernels. Those lead to adaptive decompositions of quaternionic‐valued signals of finite energy. This study is a generalization of the main results of the first author's recent research in relation to adaptive Takenaka–Malmquist systems in one complex variable. Copyright © 2011 John Wiley & Sons, Ltd.
An epidemiology model suggested by yellow fever
Authors: Cannon John R. , Galiffa Daniel J.
Published: December 2011

In this work, we construct and analyze a nonlinear reaction–diffusion epidemiology model consisting of two integral‐differential equations and an ordinary differential equation, which is suggested by various insect borne diseases, for example, Yellow Fever. We begin by defining a nonlinear auxiliary problem and establishing the existence and uniqueness of its solution via a priori estimates and a fixed point argument, from which we prove the existence and uniqueness of the classical solution to the analytic problem. Next, we develop a finite‐difference method to approximate our model and perform some numerical experiments. We conclude with a brief discussion of some subsequent extensions. Copyright © 2011 John Wiley & Sons, Ltd.
Closed‐loop performance metrics for fault detection and isolation filter and controller interaction
Authors: Pandita Rohit , Bokor József , Balas Gary
Published: December 2011

Fault detection and isolation (FDI) filters are typically synthesized for open‐loop or closed‐loop systems. The controller affects the FDI filter performance in the closed‐loop system. FDI filter performance and closed‐loop controller–filter interaction in the presence of uncertain dynamics were investigated as was the role of controller robustness on the FDI filter performance. The NASA Generic Transport Model aircraft was considered as a motivating application. Multiple example scenarios were presented to highlight the utility of FDI filter performance metrics. For example, comparing fault detection performance of different filters under identical uncertain plant dynamics and controller, the effect of different controllers on the FDI filter performance, and the effect of model uncertainty on filter performance. The Generic Transport Model aircraft FDI filter results are validated using worst‐case analysis and linear simulations. Copyright © 2011 John Wiley & Sons, Ltd.
Variation in breeding parameters of Eleonora's falcon (Falco eleonorae) and factors affecting its reproductive performance
Authors: Xirouchakis S. M. , Fric J. , Kassara C. , Portolou D. , Dimalexis A. , Karris G. , Barboutis C. , Latsoudis P. , Bourdakis S. , Kakalis E. , Sfenthourakis S.
Published: December 2011

We gathered data for a four‐year period (2004–2007) on the nesting ecology and reproductive performance of Eleonora's falcon in the Aegean Sea. We investigated in an indirect way the relation between clutch size and pre‐laying food availability, the significance of site and pair quality on productivity, and the effects of habitat and intraspecific competition on breeding success. Overall, the species selected nest sites sheltered from sun exposure but not from the prevailing wind. Hatching, fledging, and breeding success rates were estimated at 64, 72%, and 60%, respectively. Fledglings per breeding pair ranged from 1.19 to 1.75, and fledglings per successful pair from 1.84 to 2.0, between the years. Productivity depended on parental care rather than nest‐site quality. Breeding parameters varied significantly between the years, exhibiting a strong spatial yet local effect. Low success rates were recorded in specific colonies, which were attributed to adverse weather conditions and habitat degradation. Insect food availability prior to egg‐laying, estimated via plant biomass, was positively correlated to clutch size. Meanwhile, low wind strengths in August, large distances from the mainland, and population size in the vicinity of the colonies had negative effects on breeding success. Considering data at the Mediterranean scale, a longitudinal trend is observed across the breeding range of this species, with breeding parameters slightly decreasing from west to east.
Branch and bound algorithms for the maximum clique problem under a unified framework
Authors: Carmo Renato , Züge Alexandre
Published: December 2011

In this paper we review branch and bound-based algorithms proposed for the exact solution of the maximum clique problem and describe them under a unifying conceptual framework. As a proof of concept, we actually implemented eight of these algorithms as parametrized versions of one single general branch and bound algorithm.

The purpose of the present work is double folded. In the one hand, the implementation of several different algorithms under the same computational environment allows for a more precise assessment of their comparative performance at the experimental level. On the other hand we see the unifying conceptual framework provided by such description as a valuable step toward a more fine grained analysis of these algorithms.
Sentiment-based influence detection on Twitter
Authors: Bigonha Carolina , Cardoso Thiago N. C. , Moro Mirella M. , Gonçalves Marcos A. , Almeida Virgílio A. F.
Published: December 2011

The user generated content available in online communities is easy to create and consume. Lately, it also became strategically important to companies interested in obtaining population feedback on products, merchandising, etc. One of the most important online communities is Twitter: recent statistics report 65 million new tweets each day. However, processing this amount of data is very costly and a big portion of the content is simply not useful for strategic analysis. Thus, in order to filter the data to be analyzed, we propose a new method for ranking the most influential users in Twitter. Our approach is based on a combination of the user position in networks that emerge from Twitter relations, the polarity of her opinions and the textual quality of her tweets. Our experimental evaluation shows that our approach can successfully identify some of the most influential users and that interactions between users provide the best evidence to determine user influence.
Mental health promotion: Guidance and strategies
Authors: Kalra G. , Christodoulou G. , Jenkins R. , Tsipas V. , Christodoulou N. , Lecic-Tosevski D. , Mezzich J. , Bhugra D.
Published: December 2011

Public mental health incorporates a number of strategies from mental well-being promotion to primary prevention and other forms of prevention. There is considerable evidence in the literature to suggest that early interventions and public education can work well for reducing psychiatric morbidity and resulting burden of disease. Educational strategies need to focus on individual, societal and environmental aspects. Targeted interventions at individuals will also need to focus on the whole population. A nested approach with the individual at the heart of it surrounded by family surrounded by society at large is the most suitable way to approach this. This Guidance should be read along with the European Psychiatric Association (EPA) Guidance on Prevention. Those at risk of developing psychiatric disorders also require adequate interventions as well as those who may have already developed illness. However, on the model of triage, mental health and well-being promotion need to be prioritized to ensure that, with the limited resources available, these activities do not get forgotten. One possibility is to have separate programmes for addressing concerns of a particular population group, another that is relevant for the broader general population. Mental health promotion as a concept is important and this will allow prevention of some psychiatric disorders and, by improving coping strategies, is likely to reduce the burden and stress induced by mental illness.
Availability and quality of emergency obstetric and neonatal care services in Afghanistan
Authors: Kim Young‐Mi , Zainullah Partamin , Mungia Jaime , Tappis Hannah , Bartlett Linda , Zaka Nabila
Published: December 2011

Objective

To assess the availability and utilization of emergency obstetric and neonatal care (EmONC) facilities in Afghanistan, as defined by UN indicators.

Methods

In a cross‐sectional study of 78 first‐line referral facilities located in secure areas of Afghanistan, EmONC service delivery was evaluated by using Averting Maternal Deaths and Disabilities (AMDD) Program assessment tools.

Results

Forty‐two percent of peripheral facilities did not perform all 9 signal functions required of comprehensive EmONC facilities. The study facilities delivered 17% of all neonates expected in their target populations and treated 20% of women expected to experience direct complications. The population‐based rate of cesarean delivery was 1%. Most maternal deaths (96%) were due to direct causes. The direct and indirect obstetric case fatality rates were 0.8% and 0.2%, respectively.

Conclusion

Notable progress has been made in Afghanistan over the past 8 years in improving the quality, coverage, and utilization of EmONC services, but gaps remain. Re‐examination of the criteria for selecting and positioning EmONC facilities is recommended, as is the provision of high‐quality, essential maternal and neonatal health services at all levels of the healthcare system, linked by appropriate communication and functional referral systems.
Bacterial Phosphoproteomic Analysis Reveals the Correlation Between Protein Phosphorylation and Bacterial Pathogenicity
Authors: Ge Ruiguang , Shan Weiran
Published: December 2011

Increasing evidence shows that protein phosphorylation on serine, threonine and tyrosine residues is a major regulatory post-translational modification in the bacteria. This review focuses on the implications of bacterial phosphoproteome in bacterial pathogenicity and highlights recent development of methods in phosphoproteomics and the connectivity of the phosphorylation networks. Recent technical developments in the high accuracy mass spectrometry have dramatically transformed proteomics and made it possible the characterization of a few exhaustive site-specific bacterial phosphoproteomes. The high abundance of tyrosine phosphorylations in a few bacterial phosphoproteomes suggests their roles in the pathogenicity, especially in the case of pathogen–host interactions; the high abundance of multi-phosphorylation sites in bacterial phosphoprotein is a compensation of the relatively small phosphorylation size and an indicator of the delicate regulation of protein functions.
Cloning, Expression, and Homology Modeling of GroEL Protein from Leptospira Interrogans Serovar Autumnalis Strain N2
Authors: Natarajaseenivasan Kalimuthusamy , Shanmughapriya Santhanam , Velineni Sridhar , Artiushin Sergey C. , Timoney John F.
Published: December 2011

Leptospirosis is an infectious bacterial disease caused by Leptospira species. In this study, we cloned and sequenced the gene encoding the immunodominant protein GroEL from L. interrogans serovar Autumnalis strain N2, which was isolated from the urine of a patient during an outbreak of leptospirosis in Chennai, India. This groEL gene encodes a protein of 60 kDa with a high degree of homology (99% similarity) to those of other leptospiral serovars. Recombinant GroEL was overexpressed in Escherichia coli. Immunoblot analysis indicated that the sera from confirmed leptospirosis patients showed strong reactivity with the recombinant GroEL while no reactivity was observed with the sera from seronegative control patient. In addition, the 3D structure of GroEL was constructed using chaperonin complex cpn60 from Thermus thermophilus as template and validated. The results indicated a Z-score of −8.35, which is in good agreement with the expected value for a protein. The superposition of the Cα traces of cpn60 structure and predicted structure of leptospiral GroEL indicates good agreement of secondary structure elements with an RMSD value of 1.5 Å. Further study is necessary to evaluate GroEL for serological diagnosis of leptospirosis and for its potential as a vaccine component.
Airborne electromagnetic imaging of discontinuous permafrost
Authors: Minsley Burke J. , Abraham Jared D. , Smith Bruce D. , Cannia James C. , Voss Clifford I. , Jorgenson M. Torre , Walvoord Michelle A. , Wylie Bruce K. , Anderson Lesleigh , Ball Lyndsay B. , Deszcz‐Pan Maryla , Wellman Tristan P. , Ager Thomas A.
Published: December 2011

The evolution of permafrost in cold regions is inextricably connected to hydrogeologic processes, climate, and ecosystems. Permafrost thawing has been linked to changes in wetland and lake areas, alteration of the groundwater contribution to streamflow, carbon release, and increased fire frequency. But detailed knowledge about the dynamic state of permafrost in relation to surface and groundwater systems remains an enigma. Here, we present the results of a pioneering ∼1,800 line‐kilometer airborne electromagnetic survey that shows sediments deposited over the past ∼4 million years and the configuration of permafrost to depths of ∼100 meters in the Yukon Flats area near Fort Yukon, Alaska. The Yukon Flats is near the boundary between continuous permafrost to the north and discontinuous permafrost to the south, making it an important location for examining permafrost dynamics. Our results not only provide a detailed snapshot of the present‐day configuration of permafrost, but they also expose previously unseen details about potential surface – groundwater connections and the thermal legacy of surface water features that has been recorded in the permafrost over the past ∼1,000 years. This work will be a critical baseline for future permafrost studies aimed at exploring the connections between hydrogeologic, climatic, and ecological processes, and has significant implications for the stewardship of Arctic environments.
The kinematics of a transition from subduction to strike‐slip: An example from the central New Zealand plate boundary
Authors: Wallace L. M. , Barnes P. , Beavan J. , Van Dissen R. , Litchfield N. , Mountjoy J. , Langridge R. , Lamarche G. , Pondard N.
Published: December 2011

We develop a kinematic model for the transition from subduction beneath the North Island, New Zealand, to strike‐slip in the South Island, constrained by GPS velocities and active fault slip data. To interpret these data, we use an approach that inverts the kinematic data for poles of rotation of tectonic blocks and the degree of interseismic coupling on faults in the region. Convergence related to the Hikurangi subduction margin becomes very low offshore of the northern South Island, indicating that in this region the majority of the relative plate motion has been transferred onto faults within the upper plate, as suggested by previous studies. This result has implications for understanding the likely extent of subduction interface earthquake rupture in central New Zealand. Easterly trending strike slip faults (such as the Boo Boo fault) are the key features that facilitate the transfer of strike‐slip motion from the northern South Island faults further north into the southern North Island and onto the Hikurangi subduction thrust. Our results also indicate that the transition from rapid forearc rotation adjacent to the Hikurangi subduction margin to a strike‐slip dominated plate boundary (with negligible vertical‐axis rotation) in the South Island occurs via a crustal‐scale hinge or kink in the upper plate, compatible with paleomagnetic and structural geological data. Despite the ongoing tectonic evolution of the central New Zealand region, our study highlights a remarkable consistency between data sets spanning decades (GPS), thousands of years (active faulting data), and millions of years (paleomagnetic data and bedrock structure).
Fixed recurrence and slip models better predict earthquake behavior than the time‐ and slip‐predictable models: 2. Laboratory earthquakes
Authors: Rubinstein Justin L. , Ellsworth William L. , Beeler Nicholas M. , Kilgore Brian D. , Lockner David A. , Savage Heather M.
Published: December 2011

The behavior of individual stick‐slip events observed in three different laboratory experimental configurations is better explained by a “memoryless” earthquake model with fixed inter‐event time or fixed slip than it is by the time‐ and slip‐predictable models for earthquake occurrence. We make similar findings in the companion manuscript for the behavior of natural repeating earthquakes. Taken together, these results allow us to conclude that the predictions of a characteristic earthquake model that assumes either fixed slip or fixed recurrence interval should be preferred to the predictions of the time‐ and slip‐predictable models for all earthquakes. Given that the fixed slip and recurrence models are the preferred models for all of the experiments we examine, we infer that in an event‐to‐event sense the elastic rebound model underlying the time‐ and slip‐predictable models does not explain earthquake behavior. This does not indicate that the elastic rebound model should be rejected in a long‐term‐sense, but it should be rejected for short‐term predictions. The time‐ and slip‐predictable models likely offer worse predictions of earthquake behavior because they rely on assumptions that are too simple to explain the behavior of earthquakes. Specifically, the time‐predictable model assumes a constant failure threshold and the slip‐predictable model assumes that there is a constant minimum stress. There is experimental and field evidence that these assumptions are not valid for all earthquakes.
Frost flowers growing in the Arctic ocean‐atmosphere–sea ice–snow interface: 1. Chemical composition
Authors: Douglas Thomas A. , Domine Florent , Barret Manuel , Anastasio Cort , Beine Harry J. , Bottenheim Jan , Grannas Amanda , Houdier Stephan , Netcheva Stoyka , Rowland Glenn , Staebler Ralf , Steffen Alexandra
Published: December 2011

Frost flowers, intricate featherlike crystals that grow on refreezing sea ice leads, have been implicated in lower atmospheric chemical reactions. Few studies have presented chemical composition information for frost flowers over time and many of the chemical species commonly associated with Polar tropospheric reactions have never been reported for frost flowers. We undertook this study on the sea ice north of Barrow, Alaska to quantify the major ion, stable oxygen and hydrogen isotope, alkalinity, light absorbance by soluble species, organochlorine, and aldehyde composition of seawater, brine, and frost flowers. For many of these chemical species we present the first measurements from brine or frost flowers. Results show that major ion and alkalinity concentrations, stable isotope values, and major chromophore (NO3− and H2O2) concentrations are controlled by fractionation from seawater and brine. The presence of these chemical species in present and future sea ice scenarios is somewhat predictable. However, aldehydes, organochlorine compounds, light absorbing species, and mercury (part 2 of this research and Sherman et al. (2012)) are deposited to frost flowers through less predictable processes that probably involve the atmosphere as a source. The present and future concentrations of these constituents in frost flowers may not be easily incorporated into future sea ice or lower atmospheric chemistry scenarios. Thinning of Arctic sea ice will likely present more open sea ice leads where young ice, brine, and frost flowers form. How these changing ice conditions will affect the interactions between ice, brine, frost flowers and the lower atmosphere is unknown.
A climate sensitivity estimate using Bayesian fusion of instrumental observations and an Earth System model
Authors: Olson Roman , Sriver Ryan , Goes Marlos , Urban Nathan M. , Matthews H. Damon , Haran Murali , Keller Klaus
Published: December 2011

Current climate model projections are uncertain. This uncertainty is partly driven by the uncertainty in key model parameters such as climate sensitivity (CS), vertical ocean diffusivity (Kv), and strength of anthropogenic sulfate aerosol forcing. These parameters are commonly estimated using ensembles of model runs constrained by observations. Here we obtain a probability density function (pdf) of these parameters using the University of Victoria Earth System Climate Model (UVic ESCM) ‐ an intermediate complexity model with a dynamic three‐dimensional ocean. Specifically, we run an ensemble of UVic ESCM runs varying parameters that affectCS, ocean vertical diffusion, and the effects of anthropogenic sulfate aerosols. We use a statistical emulator that interpolates the UVic ESCM output to parameter settings where the model was not evaluated. We adopt a Bayesian approach to constrain the model output with instrumental surface temperature and ocean heat observations. Our approach accounts for the uncertainties in the properties of model‐data residuals. We use a Markov chain Monte Carlo method to obtain a posterior pdf of these parameters. The mode of the climate sensitivity estimate is 2.8°C, with the corresponding 95% credible interval ranging from 1.8 to 4.9°C. These results are generally consistent with previous studies. TheCS pdf is sensitive to the assumptions about the priors, to the effects of anthropogenic sulfate aerosols, and to the background vertical ocean diffusivity. Our method can be used with more complex climate models.
Long‐term aerosol measurements in Gran Canaria, Canary Islands: Particle concentration, sources and elemental composition
Authors: Gelado‐Caballero María D. , López‐García Patricia , Prieto Sandra , Patey Matthew D. , Collado Cayetano , Hérnández‐Brito José J.
Published: December 2011

There are very few sets of long‐term measurements of aerosol concentrations over the North Atlantic Ocean, yet such data is invaluable in quantifying atmospheric dust inputs to this ocean region. We present an 8‐year record of total suspended particles (TSP) collected at three stations on Gran Canaria Island, Spain (Taliarte at sea level, Tafira 269 m above sea level (a.s.l.) and Pico de la Gorra 1930 m a.s.l.). Using wet and dry deposition measurements, the mean dust flux was calculated at 42.3 mg m−2 d−1. Air mass back trajectories (HYSPLIT, NOAA) suggested that the Sahara desert is the major source of African dust (dominant during 32–50% of days), while the Sahel desert was the major source only 2–10% of the time (maximum in summer). Elemental composition ratios of African samples indicate that, despite the homogeneity of the dust in collected samples, some signatures of the bedrocks can still be detected. Differences were found for the Sahel, Central Sahara and North of Sahara regions in Ti/Al, Mg/Al and Ca/Al ratios, respectively. Elements often associated with pollution (Pb, Cd, Ni, Zn) appeared to share a common origin, while Cu may have a predominantly local source, as suggested by a decrease in the enrichment factor (EF) of Cu during dust events. The inter‐annual variability of dust concentrations is investigated in this work. During winter, African dust concentration measurements at the Pico de la Gorra station were found to correlate with the North Atlantic Oscillation (NAO) index.
Carbon and oxygen cycles: Sensitivity to changes in environmental forcing in a coastal upwelling system
Authors: Bianucci L. , Denman K. L.
Published: December 2011

Biogeochemical cycles in the coastal ocean are changing and will continue to change in response to a changing climate. Effects on the oxygen and carbon cycles are particularly important, as either episodic or permanent shifts toward lower oxygen and/or higher inorganic carbon conditions can impact coastal ecosystems negatively. Here we study the sensitivity of these cycles to changes that may occur in the coastal ocean, focusing on a summer wind‐driven upwelling region off southern Vancouver Island shelf. We use a quasi 2‐D configuration of the Regional Ocean Modeling System (ROMS) to perform six sensitivity experiments. Results indicate that carbon and oxygen cycles in this region may be significantly affected by an altered upwelling season, a shallower offshore Oxygen Minimum Zone, and a carbon‐enriched environment. Combinations of these scenarios suggest a potentially increasing risk for the development of coastal hypoxia and corrosive conditions in the region.
Forecasting F10.7 with solar magnetic flux transport modeling
Authors: Henney C. J. , Toussaint W. A. , White S. M. , Arge C. N.
Published: December 2011

A new method is presented here to forecast the solar 10.7 cm (2.8 GHz) radio flux, abbreviated F10.7, utilizing advanced predictions of the global solar magnetic field generated by a flux transport model. Using indices derived from the absolute value of the solar magnetic field, we find good correlation between the observed photospheric magnetic activity and the observed F10.7 values. Comparing magnetogram data observed within 6 hours of the F10.7 measurements during the years 1993 through 2010, the Spearman correlation coefficient, rs, for an empirical model of F10.7 is found to be 0.98. In addition, we find little change in the empirical model coefficients and correlations between the first and second 9 year intervals of the 18 year period investigated. By evolving solar magnetic synoptic maps forward 1–7 days, this new method provides a realistic estimation of the Earth‐side solar magnetic field distribution used to forecast F10.7. Spearman correlation values of approximately 0.97, 0.95, and 0.93 are found for 1 day, 3 day, and 7 day forecasts, respectively. The method presented here can be expanded to forecast other space weather parameters, e.g., total solar irradiance and extreme ultraviolet flux. In addition, near‐term improvements to the F10.7 forecasting method, e.g., including far‐side magnetic data with solar magnetic flux transport, are discussed.
Happy birthday to RU
Authors: Jacobs Howy
Published: December 2011

Despite some recent reforms, Howy argues that Russia needs to do a lot more to regain its rightful place in the world league table of science
Time Trends for Livestock Production in Saskatchewan, Canada: 1905-2011
Authors: Rayne Sierra , Forest Kaya
Published: December 2011

Saskatchewan, Canada, with a total land area of 651,900 km^2^, is one of the world’s most productive agricultural regions. A broad variety of livestock are raised in the province, including cattle, pigs, poultry, sheep/goats, llama, ostrich, elk, deer, and bison. In 2010, the total revenue from the Saskatchewan livestock sector was CAD$1.6 billion. Over the past century, changing industry economics and advances in scientific, technical, and engineering knowledge and practices have affected the amount and type of livestock produced. The current work examines time trends for livestock production since Saskatchewan was created in 1905. While production trends vary widely by livestock type, most sectors display clearly increasing amounts of industry consolidation over time, warranting more detailed investigations into the socio-economical and technological drivers behind such changes.
Episodic Long-Term Memory of Spoken Discourse Masked by Speech: What Is the Role for Working Memory Capacity?
Authors: Sörqvist Patrik , Rönnberg Jerker
Published: December 2011

Purpose

To investigate whether working memory capacity (WMC) modulates the effects of to-be-ignored speech on the memory of materials conveyed by to-be-attended speech.

Method

Two tasks (reading span, Daneman & Carpenter, 1980; Rönnberg et al., 2008; and size-comparison span, Sörqvist, Ljungberg, & Ljung, 2010) were used to measure individual differences in WMC. Episodic long-term memory of spoken discourse was measured by requesting participants to listen to stories masked either by normal speech or by a rotated version of that speech and to subsequently answer questions on the content of the stories.

Results

Normal speech impaired performance on the episodic long-term memory test, and both WMC tasks were negatively related to this effect, indicating that individuals with high WMC are less susceptible to disruption. Moreover, further analyses revealed that size-comparison span (a task that requires resolution of semantic confusion by inhibition processes) is a stronger predictor of the effect than is reading span.

Conclusions

Cognitive control processes support listening in adverse conditions. In particular, inhibition processes acting to resolve semantic confusion seem to underlie the relationship between WMC and susceptibility to distraction from masking speech.
Cauda Equina Syndrome following Decompression for Spinal Stenosis
Authors: Duncan Jan William , Bailey Richard Anthony
Published: December 2011

Cauda equina syndrome following decompression for spinal stenosis appears to occur more commonly than the literature suggests. A large series of spinal stenosis decompressions was reviewed. Based on these findings, a theory is put forth as to the cause of this complication. One hundred seventy-five cases of decompression for spinal stenosis done over a 2.5-year period were reviewed. Follow-up was 1year to 2 years and 4 months. There were 14 cases of postoperative urinary retention, for an incidence of 8%. Of those, five were ultimately diagnosed with cauda equina syndrome, for an incidence of 2.8%. Of the nine cases that were not diagnosed as cauda equina syndrome, five resolved spontaneously over 2 to 6 weeks. The remaining four were diagnosed as having mechanical urinary problems (e.g., prostate or prolapsed bladder) that required surgical treatment. Anal sphincter monitoring at the time of surgery was not predictive in those patients who developed cauda equina syndrome. All patients who developed cauda equina syndrome improved over 3 to 9 months, but none completely resolved. Three cases underwent further decompression with no apparent improvement. Cauda equina syndrome occurs in 2.8% of decompressions for spinal stenosis.
Thoracic Fracture through a Prior Instrumented Arthrodesis in a Patient with Ankylosing Spondylitis without Hardware Loosening: A Case Report
Authors: Saldua Nelson S. , Harrop James S.
Published: December 2011

The objective of this article is to report a case of a patient with ankylosing spondylitis who sustained a fracture through a prior solid arthrodesis without loosening or changing posterior instrumentation. There have been few cases reported of a patient with ankylosing spondylitis suffering a fracture through a prior instrumented arthrodesis. None have noted the instrumentation remaining intact with the fracture through the middle of the construct. The surgeon must be aware of this possibility to avoid spinal instability that may lead to a neurological deficit. We retrospectively reviewed the case. A review of the literature was performed through a PubMed search. A patient was found to have a fracture within a prior construct despite the presence of a posterior instrumentation. The mechanism of failure was a three-column spine fracture with “bending” of the rods. This patient was treated with a revision posterior/anterior instrumentation and fusion with placement of larger-diameter rods for added stiffness. Fractures through a prior instrumented arthrodesis are rare but still can occur in the ankylosing spondylitis patient. Given the higher risk of epidural hematoma and neurological compromise in this patient population, the surgeon must keep this on the differential diagnosis when treating patients with a prior instrumented arthrodesis.
Invited Review Article: Photopyroelectric calorimeter for the simultaneous thermal, optical, and structural characterization of samples over phase transitions
Authors: Zammit U. , Marinelli M. , Mercuri F. , Paoloni S. , Scudieri F.
Published: December 2011

The study of thermophysical properties is of great importance in several scientific fields. Among them, the heat capacity, for example, is related to the microscopic structure of condensed matter and plays an important role in monitoring the changes in the energy content of a system. Calorimetric techniques are thus of fundamental importance for characterizing physical systems, particularly in the vicinity of phase transitions where energy fluctuations can play an important role. In this work, the ability of the Photopyroelctric calorimetry to study the versus temperature behaviour of the specific heat and of the other thermal parameters in the vicinity of phase transitions is outlined. The working principle, the theoretical basis, the experimental configurations, and the advantages of this technique, with respect to the more conventional ones, have been described and discussed in detail. The integrations in the calorimetric setup giving the possibility to perform, simultaneously with the calorimetric studies, complementary kind of characterizations of optical, structural, and electrical properties are also described. A review of the results obtained with this technique, in all its possible configurations, for the high temperature resolution studies of the thermal parameters over several kinds of phase transitions occurring in different systems is presented and discussed.
Limitations of the terahertz photomixer
Authors: Nowak Kacper , Jarzab Przemyslaw P. , Plinski Edward F.
Published: December 2011

In the paper, Fourier transform has been used for calculations of a refractive index of dielectric samples measured in the terahertz photomixer arrangement. We considered measurement limitations caused by a sampling frequency and a photomixer bandwidth.
First passage time distribution of chaperone driven polymer translocation through a nanopore: Homopolymer and heteropolymer cases
Authors: Abdolvahab Rouhollah Haji , Metzler Ralf , Ejtehadi Mohammad Reza
Published: December 2011

Combining the advection-diffusion equation approach with Monte Carlo simulations we study chaperone driven polymer translocation of a stiff polymer through a nanopore. We demonstrate that the probability density function of first passage times across the pore depends solely on the Péclet number, a dimensionless parameter comparing drift strength and diffusivity. Moreover it is shown that the characteristic exponent in the power-law dependence of the translocation time on the chain length, a function of the chaperone-polymer binding energy, the chaperone concentration, and the chain length, is also effectively determined by the Péclet number. We investigate the effect of the chaperone size on the translocation process. In particular, for large chaperone size, the translocation progress and the mean waiting time as function of the reaction coordinate exhibit pronounced sawtooth-shapes. The effects of a heterogeneous polymer sequence on the translocation dynamics is studied in terms of the translocation velocity, the probability distribution for the translocation progress, and the monomer waiting times.
High strain-rate plastic flow in Al and Fe
Authors: Smith R. F. , Eggert J. H. , Rudd R. E. , Swift D. C. , Bolme C. A. , Collins G. W.
Published: December 2011

Thin Fe and Al foils were ramp-compressed over several to tens of ns timescales to study the time-dependence associated with the onset of plastic flow. Peak stress states of 15–200 GPa were achieved through laser ramp-compression where the strain rate was varied, shot-to-shot, between 106 to 108 s−1. Our data combined with data from other dynamic compression platforms reveals a strong correlation between the peak elastic precursor stress, σE, and the strain rate at the onset of plastic flow, ɛ·p. In fcc Al, phonon drag dislocation flow dominates above ɛ·p~103s-1 and σE ∼ 0.03 GPa where σE scales as ɛ·p0.43. By contrast, the Al alloy 6061-T6 exhibits a relatively weak dependency of σE with ɛ·p up to strain rates of ∼107 s−1. Our Fe data, reveals a sharp increase in σE at ɛ·p>5×106s-1. This is consistent with a transition in plastic flow to a phonon drag regime.
Conformational fluctuations of a protein–DNA complex and the structure and ordering of water around it
Authors: Sinha Sudipta Kumar , Bandyopadhyay Sanjoy
Published: December 2011

Protein–DNA binding is an important process responsible for the regulation of genetic activities in living organisms. The most crucial issue in this problem is how the protein recognizes the DNA and identifies its target base sequences. Water molecules present around the protein and DNA are also expected to play an important role in mediating the recognition process and controlling the structure of the complex. We have performed atomistic molecular dynamics simulations of an aqueous solution of the protein–DNA complex formed between the DNA binding domain of human TRF1 protein and a telomeric DNA. The conformational fluctuations of the protein and DNA and the microscopic structure and ordering of water around them in the complex have been explored. In agreement with experimental studies, the calculations reveal conformational immobilization of the terminal segments of the protein on complexation. Importantly, it is discovered that both structural adaptations of the protein and DNA, and the subsequent correlation between them to bind, contribute to the net entropy loss associated with the complex formation. Further, it is found that water molecules around the DNA are more structured with significantly higher density and ordering than that around the protein in the complex.
A semi-analytical model for semiconductor solar cells
Authors: Ding D. , Johnson S. R. , Yu S.-Q. , Wu S.-N. , Zhang Y.-H.
Published: December 2011

A semi-analytical model is constructed for single- and multi-junction solar cells. This model incorporates the key performance aspects of practical devices, including nonradiative recombination, photon recycling within a given junction, spontaneous emission coupling between junctions, and non-step-like absorptance and emittance with below-bandgap tail absorption. Four typical planar structures with the combinations of a smooth/textured top surface and an absorbing/reflecting substrate (or backside surface) are investigated, through which the extracted power and four types of fundamental loss mechanisms, transmission, thermalization, spatial-relaxation, and recombination loss are analyzed for both single- and multi-junction solar cells. The below-bandgap tail absorption increases the short-circuit current but decreases the output and open-circuit voltage. Using a straightforward formulism this model provides the initial design parameters and the achievable efficiencies for both single- and multiple-junction solar cells over a wide range of material quality. The achievable efficiency limits calculated using the best reported materials and AM1.5 G one sun for GaAs and Si single-junction solar cells are, respectively, 27.4 and 21.1% for semiconductor slabs with a flat surface and a non-reflecting index-matched absorbing substrate, and 30.8 and 26.4% for semiconductor slabs with a textured surface and an ideal 100% reflecting backside surface. Two important design rules for both single- and multi-junction solar cells are established: i) the optimal junction thickness decreases and the optimal bandgap energy increases when nonradiative recombination increases; and ii) the optimal junction thickness increases and the optimal bandgap energy decreases for higher solar concentrations.
Crystal structure and magnetic performance of nanocrystalline SmCo9.8 alloy
Authors: Zhang Zhexu , Song Xiaoyan , Xu Wenwu , Li Dingpeng , Liu Xuemei
Published: December 2011

Starting with the ingot with a nominal stoichiometric composition of SmCo9.8, the nanocrystalline bulk with ultrafine nanograin structure was prepared by a route combing ball milling and spark plasma sintering. The phase formation, microstructure, crystal lattice characteristics, and magnetic performance of the nanocrystalline SmCo9.8 alloy were investigated. The TbCu7-type solid solution of the SmCo9.8 composition was obtained, and the crystal structure of the nanocrystalline 1:9.8 H was constructed. The magnetic features were disclosed through nanostructuring to obtain the single metastable 1:9.8 H. It was found that the nanocrystalline SmCo9.8 alloy has high saturation magnetization and Curie temperature. The study presents a new understanding of the nanoscale-stabilized TbCu7-type solid solution of the SmCo9.8 composition and may promote the development of SmCo9.8-type alloys as candidates for the high-temperature permanent magnets, based on the coercivity improvement.
Nanoscale density fluctuations in swift heavy ion irradiated amorphous SiO2
Authors: Kluth P. , Pakarinen O. H. , Djurabekova F. , Giulian R. , Ridgway M. C. , Byrne A. P. , Nordlund K.
Published: December 2011

We report on the observation of nanoscale density fluctuations in 2 μm thick amorphous SiO2 layers irradiated with 185 MeV Au ions. At high fluences, in excess of approximately 5 × 1012 ions/cm2, where the surface is completely covered by ion tracks, synchrotron small angle x-ray scattering measurements reveal the existence of a steady state of density fluctuations. In agreement with molecular dynamics simulations, this steady state is consistent with an ion track “annihilation” process, where high-density regions generated in the periphery of new tracks fill in low-density regions located at the center of existing tracks.