bluuebunny/crossref_metadata_2025 huggingface dataset:
Advanced antistatic/anticorrosion coatings prepared from polystyrene composites incorporating dodecylbenzenesulfonic acid‐doped SiO2@polyaniline core–shell microspheres
Authors: Weng Chang‐Jian , Chen Ya‐Lun , Jhuo Yu‐Sian , Yi‐Li Lin , Yeh Jui‐Ming
Published: September 2012

We present the preparation of advanced antistatic and anticorrosion coatings of polystyrene (PS) incorporating a suitable amount of dodecylbenzenesulfonic acid (DBSA)‐doped SiO2@polyaniline (SP) core–shell microspheres. First, aniline‐anchored SiO2 (AS) microspheres that were about 850 nm in diameter were synthesized using the conventional base‐catalyzed sol–gel process with tetraethyl orthosilicate in the presence of N‐[3‐(trimethoxysilyl)propyl]aniline. SP core–shell microspheres were then synthesized by chemical oxidative polymerization of aniline monomers with ammonium persulfate as an oxidizing agent in the presence of the AS microspheres. The polyaniline shell thickness of the as‐prepared core–shell microspheres was estimated to be about 120 nm. The AS and SP microspheres were further characterized using Fourier transform infrared spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy. The as‐synthesized DBSA‐doped SP core–shell microspheres were then blended into PS using N‐methyl‐2‐pyrrolidone as solvent and then cast onto a cold–rolled steel (CRS) electrode to obtain antistatic and anticorrosion coatings with a thickness of about 10 µm. The corrosion protection efficiency of the as‐prepared coating materials on the CRS electrode was investigated using a series of systematic electrochemical measurements under saline conditions. The enhanced corrosion protection ability of the PS/SP composite coatings may be attributed to the formation of a dense passive metal oxide layer induced by the redox catalytic effect of the polyaniline shell of the as‐synthesized core–shell microspheres, as evidenced by electron spectroscopy for chemical analysis and SEM observations. Moreover, the PS composite coating containing 10 wt% of the SP core–shell microspheres showed an electrical resistance of about 3.65 × 109Ω cm−2, which meets the requirements for antistatic applications. Copyright © 2012 Society of Chemical Industry
Enhancing lepton flavour violation in the supersymmetric inverse seesaw beyond the dipole contribution
Authors: Abada Asmaa , Das Debottam , Vicente Avelino , Weiland Cédric
Published: September 2012

Abstract

In minimal supersymmetric models the Z-penguin usually provides sub-dominant contributions to charged lepton flavour violating observables. In this study, we consider the supersymmetric inverse seesaw in which the non-minimal particle content allows for dominant contributions of the Z-penguin to several lepton flavour violating observables. In particular, and due to the low-scale (TeV) seesaw, the penguin contribution to, for instance, Br(μ → 3e) and μ − e conversion in nuclei, allows to render some of these observables within future sensitivity reach. Moreover, we show that in this framework, the Z-penguin exhibits the same non-decoupling behaviour which had previously been identified in flavour violating Higgs decays in the Minimal Supersymmetric Standard Model.
Small Liver Remnants Are More Vulnerable to Ischemia/Reperfusion Injury after Extended Hepatectomies: A Case–Control Study
Authors: Theodoraki Kassiani , Arkadopoulos Nikolaos , Nastos Constantinos , Vassiliou Ioannis , Karmaniolou Iosifina , Smyrniotis Vassilios
Published: September 2012

Background

There is evidence that small‐for‐size liver grafts are more vulnerable to ischemia/reperfusion injury after liver transplantation. We hypothesized that ischemic injury is more pronounced in small liver remnants after major hepatectomies.

Methods

Fifteen patients underwent extended hepatectomy with remnant liver mass less than 30 % of standard liver weight (study group). These patients were matched with patients who underwent minor liver resection, with liver remnants equal to or more than 70 % of standard liver weight (control group). Ischemia/reperfusion injury was assessed by tissue caspase‐3 activity postoperatively as well as peak aspartate aminotransferase (AST) values and a‐glutathione S‐transferase (α‐GST) levels adjusted for remnant liver weight. In addition, caspase‐3 activity and adjusted serum markers of hepatocyte injury were correlated with the degree of postoperative portal hypertension.

Results

Caspase‐3 activity was higher in patients with small liver remnants (22.66 ± 6.57 vs. 12.60 ± 4.06 count per high‐power field, p < 0.001). Serum markers of hepatocyte injury, when adjusted per gram of liver remnant, were found to be higher in the study group than in the control group (AST: 1.26 ± 0.25 vs. 0.54 ± 0.11 IU g−1, p < 0.001; α‐GST: 0.14 ± 0.02 vs. 0.08 ± 0.01 IU g−1, p < 0.001). Tissue caspase‐3 expression in the small liver remnant group correlated with both AST and α‐GST levels adjusted per gram of liver remnant (r2 = 0.51, p = 0.005 and r2 = 0.71, p < 0.001, respectively). Significant correlations between postoperative portal hypertension and the same markers as well as caspase‐3 activity were also demonstrated.

Conclusion

Liver remnants less than 30 % of standard liver weight are much more susceptible to ischemia/reperfusion injury than controls twice the size. Adjustment of serum markers of hepatocyte injury to the liver remnant weight depicts injury more accurately.
Analgesic Efficacy of Bilateral Superficial Cervical Plexus Block in Robot‐Assisted Endoscopic Thyroidectomy Using a Transaxillary Approach
Authors: Shin Seokyung , Chung Woung Youn , Jeong Jong Ju , Kang Sang‐Wook , Oh Young Jun
Published: September 2012

Background

Nerve blocks and infiltration with local anesthetics are commonly employed methods for postoperative pain control. This prospective, randomized trial was conducted to determine whether bilateral superficial cervical plexus block (BSCPB) is effective for reducing acute postoperative pain after robot‐assisted endoscopic thyroidectomy (RAET) and to compare its effects with that of local wound infiltration (LWI).

Methods

Ninety‐seven patients who were to undergo RAET were randomly assigned to one of three groups to receive BSCPB with either 20 mL of 0.525 % ropivacaine (BSCPB group, n = 32) or 20 mL of isotonic sodium chloride solution (Control group, n = 32) or LWI with 20 mL of 0.525 % ropivacaine (LWI group, n = 33). Postoperative pain scores were assessed at the postoperative anesthesia care unit (PACU) and at 6, 24, and 48 h postoperatively using a visual analog scale (VAS). Patients with VAS scores of ≥40 were administered rescue analgesics according to a standardized protocol. The main outcome variables were pain scores during the first postoperative 24 h and the number of patients requiring postoperative analgesic rescue.

Results

The BSCBP and LWI groups showed lower pain scores compared with the Control group at the PACU. The BSCPB group continued to show significantly lower pain scores compared with the LWI and Control groups at postoperative 6 and 24 h. The number of patients requiring analgesic rescue at the PACU was lower in the BSCPB and LWI groups than in the Control group. The number of patients requiring additional rescue analgesics after discharge from the PACU until the first 24 postoperative h was lower in the BSCPB group than in the LWI group.

Conclusions

BSCPB and LWI are effective for reducing pain scores and analgesic requirements during the immediate postoperative period in patients who undergo RAET, with BSCPB being superior to LWI at postoperative 6–24 h.
North American Freshwater Mussels
Authors: Haag Wendell R.
Published: September 2012

This well-illustrated book highlights freshwater mussels' fabulous diversity, amazing array of often bizarre ecological adaptations and their dire conservation plight. Summarizing and synthesizing historical and contemporary information as well as original research and analysis, the book describes the diverse array of mussel life history strategies and builds a cohesive narrative culminating in the development of explicit frameworks to explain pervasive patterns in mussel ecology. The fascinating and colorful role of mussels in human society is also described in detail, including the little-known pearl button industry of the early 1900s and the wild and often violent shell harvest of the 1990s. The final chapter details humans' efforts to save these fascinating animals and gives a prognosis for the future of the North American fauna. The book provides the first comprehensive review of mussel ecology and conservation for scientists, natural resource professionals, students and natural history enthusiasts.
The Rise of Global Corporate Social Responsibility
Authors: Dashwood Hevina S.
Published: September 2012

Combining insights from international relations theory with institutional approaches from organization theory and public policy, this book provides a complete explanation for the adoption of corporate social responsibility (CSR), showing how global norms influenced CSR adoption in the mining industry. Global normative developments have clearly had an important influence on major mining companies: by the mid-2000s, the majority had adopted sustainable development as a normative frame for their CSR policies and practices. However, there is significant variation between firms in terms of the timing, degree of commitment, and the willingness to assume a leadership role in promoting global standards for the mining industry. The author finds that attributes internal to the firm, including the critical role of leadership, and the way in which management responds to the institutional context and operational challenges faced in different countries are important influences on CSR adoption and important factors explaining variation.
Social Rights and Duties
Authors: Stephen Leslie
Published: September 2012

Sir Leslie Stephen (1832–1904), the founding editor of the Dictionary of National Biography, and a writer on philosophy, ethics, and literature, was educated at Eton, King's College London and Trinity College, Cambridge, where he remained as a fellow and a tutor for a number of years. Though a sickly child, he later became a keen and successful mountaineer, taking part in first ascents of nine peaks in the Alps. In 1871 he became editor of the Cornhill Magazine. During his eleven-year tenure, he wrote two successful books on ethics, including The Science of Ethics in 1892, which was widely adopted as a standard textbook. This two-volume work, which was first published in 1896, brings together the lectures he gave to various ethical societies, mostly in London. In Volume 2, he discusses the ethical issues surrounding a range of topics, including luxury, heredity, crime and punishment, and duty.
The Garden of Asia
Authors: Farrer Reginald John
Published: September 2012

Reginald J. Farrer (1880–1920) was a traveller and plant collector who was an important influence on horticultural style in England. In 1902 he embarked on an expedition to Asia, where he was inspired by the rock gardens of Tokyo, Yokohama and Beijing, and discovered plant species such as Clematis macropetala, and the eponymous Geranium farreri and Viburnum farreri, which are now common in European gardens. In his first book, published in 1904, he records his experiences in Japan and other Asian countries, vividly recounting his impressions of, and his passion for, eastern landscape, terrain, plantations, forestry and flora, of which the aesthetic characteristics became central to the rockeries and shrubberies he created on his return home. Farrer died while on an expedition at the early age of forty, but the legacy of his highly influential writings and his wide-ranging plant introductions remains significant today.
Atonement and Self-Sacrifice in Nineteenth-Century Narrative
Authors: Schramm Jan-Melissa
Published: September 2012

Jan-Melissa Schramm explores the conflicted attitude of the Victorian novel to sacrifice, and the act of substitution on which it depends. The Christian idea of redemption celebrated the suffering of the innocent: to embrace a life of metaphorical self-sacrifice was to follow in the footsteps of Christ's literal Passion. Moreover, the ethical agenda of fiction relied on the expansion of sympathy which imaginative substitution was seen to encourage. But Victorian criminal law sought to calibrate punishment and culpability as it repudiated archaic models of sacrifice that scapegoated the innocent. The tension between these models is registered creatively in the fiction of novelists such as Dickens, Gaskell and Eliot, at a time when acts of Chartist protest, national sacrifices made during the Crimean War, and the extension of the franchise combined to call into question what it means for one man to 'stand for', and perhaps even 'die for', another.
Aristotle on Desire
Authors: Pearson Giles
Published: September 2012

Desire is a central concept in Aristotle's ethical and psychological works, but he does not provide us with a systematic treatment of the notion itself. This book reconstructs the account of desire latent in his various scattered remarks on the subject and analyses its role in his moral psychology. Topics include: the range of states that Aristotle counts as desires (orexeis); objects of desire (orekta) and the relation between desires and envisaging prospects; desire and the good; Aristotle's three species of desire: epithumia (pleasure-based desire), thumos (retaliatory desire) and boulêsis (good-based desire - in a narrower notion of 'good' than that which connects desire more generally to the good); Aristotle's division of desires into rational and non-rational; Aristotle and some current views on desire; and the role of desire in Aristotle's moral psychology. The book will be of relevance to anyone interested in Aristotle's ethics or psychology.
Islamic Schools in Modern Turkey
Authors: Ozgur Iren
Published: September 2012

In recent years, the Islamization of Turkish politics and public life has been the subject of much debate in Turkey and the West. This book makes an important contribution to those debates by focusing on a group of religious schools, known as Imam-Hatip schools, founded a year after the Turkish Republic, in 1924. At the outset, the main purpose of Imam-Hatip schools was to train religious functionaries. However, in the ensuing years, the curriculum, function and social status of the schools have changed dramatically. Through ethnographic and textual analysis, the book explores how Imam-Hatip school education shapes the political socialization of the schools' students, those students' attitudes and behaviours and the political and civic activities of their graduates. By mapping the schools' connections to Islamist politicians and civic leaders, the book sheds light on the significant, yet often overlooked, role that the schools and their communities play in Turkey's Islamization at the high political and grassroots levels.
Local temperature perturbations of the boundary layer in the regime of free viscous–inviscid interaction
Authors: Koroteev M. V. , Lipatov I. I.
Published: September 2012

We analyse the disturbed flow in the subsonic laminar boundary layer, disturbances being generated by local heating elements, which are placed on the surface. It is exhibited that these flows are described in terms of free interaction theory for specific sizes of thermal sources. We construct the numerical solution for the case of a flat subsonic stream in the viscous asymptotic layer, in which the flow is described by nonlinear equations for vorticity, temperature and an interaction condition which provides the influence of perturbations to the pressure in the main order. The obtained solutions are compared with those for corresponding linear problems with small perturbations. It is demonstrated that strong temperature perturbations in some situations allow us to obtain the flow close to the separated flow.
PEARL: A Reflective Story About Decolonising Pedagogy in Indigenous Australian Studies
Authors: Mackinlay Elizabeth
Published: September 2012

In this article, I take a creative and autoethnographic approach to reflect upon processes of decolonisation in Indigenous Australian studies classrooms. Positioning myself as a non-Indigenous educator, I take the reader on a journey through my search for pedagogy which makes space for the colonial, difficult and messy politics of race, whiteness and knowledge to be actively challenged, deconstructed and reimagined in this context as PEARL.
Emerging concepts: from coeliac disease to non-coeliac gluten sensitivity
Authors: Aziz Imran , Sanders David S.
Published: September 2012

The rise in gluten consumption over time has led to the increasing recognition of coeliac disease (CD) with associated complications. However, only recently has there been an appreciation that the spectrum of gluten-related disorders is greater than just CD, which may explain the growing global popularity in gluten-free products. Current literature suggests that a newly recognised clinical entity in the form of non-coeliac gluten sensitivity (NCGS) may be the most common gluten-related disorder encountered by healthcare professionals, although its exact prevalence is as yet unknown. This article will review the historical relationship between mankind and gluten as well as the progressive recognition that it is possible for gluten to have a deleterious effect on our health. To this effect we discuss the prevalence, diagnosis and complications of CD including the benefits derived from a gluten-free diet (GFD). Finally, we discuss our current understanding of NCGS, in addition to highlighting the need for further research to determine the extent, clinicopathological features and serological biomarkers to help recognise this emerging condition in clinical practice.
Obligate larval inhibition of Ostertagia gruehneri in Rangifer tarandus? Causes and consequences in an Arctic system
Authors: HOAR BRYANNE M. , EBERHARDT ALEXANDER G. , KUTZ SUSAN J.
Published: September 2012

Larval inhibition is a common strategy of Trichostrongylidae nematodes that may increase survival of larvae during unfavourable periods and concentrate egg production when conditions are favourable for development and transmission. We investigated the propensity for larval inhibition in a population of Ostertagia gruehneri, the most common gastrointestinal Trichostrongylidae nematode of Rangifer tarandus. Initial experimental infections of 4 reindeer with O. gruehneri sourced from the Bathurst caribou herd in Arctic Canada suggested that the propensity for larval inhibition was 100%. In the summer of 2009 we infected 12 additional reindeer with the F1 and F2 generations of O. gruehneri sourced from the previously infected reindeer to further investigate the propensity of larval inhibition. The reindeer were divided into 2 groups and half were infected before the summer solstice (17 June) and half were infected after the solstice (16 July). Reindeer did not shed eggs until March 2010, i.e. 8 and 9 months post-infection. These results suggest obligate larval inhibition for at least 1 population of O. gruehneri, a phenomenon that has not been conclusively shown for any other trichostrongylid species. Obligate inhibition is likely to be an adaptation to both the Arctic environment and to a migratory host and may influence the ability of O. gruehneri to adapt to climate change.
The Persian κάρδακες
Authors: Charles Michael B.
Published: September 2012

Persian troops denominated by Greek writers as κάρδακες appear infrequently in our sources for Achaemenid history, though they are recorded as having a substantial presence at Issus (333 BC). A comprehensive study of these troops is lacking and is of potentially great importance to our understanding of the military system of the Achaemenids, particularly after Xerxes' failed enterprise against Greece, and in light of the 10,000 Immortals' general disappearance from the literary record. Whether they were (a) light or heavy infantry and (b) mercenaries or native Persians has long been the subject of debate, with no particularly conclusive results. This study dismisses Strabo as a useful source on the κάρδακες, and attempts to reconcile the divergent source traditions of Arrian, who describes them as , and Callisthenes (recorded by Polybius), who writes of Persian πελτασταί at Issus. From an investigation of a wide variety of texts, together with lexicographical sources, it is possible to conclude that the hitherto enigmatic κάρδακες were general-purpose infantry not dissimilar to Iphicratean πελτασταί, and that, collectively, they constituted an ethnically diverse infantry force.
Attic Idylls: Hierarchies of Herdsmen and Social Status in Alciphron and Longus
Authors: Hodkinson Owen
Published: September 2012

The ‘hierarchy of herdsmen’ in pastoral (cowherd > shepherd > goatherd) as discussed by ancient critics of Theocritus and Virgil was an important facet of ancient readers' engagement with this literature; it was known to imperial authors of prose pastoral Longus (1.16.1) and Alciphron (2.33.1-2), who each allude to it and adapt it to their own unique receptions of the pastoral tradition. Alciphron is concerned with hierarchies of wealth and status among his ‘low’ characters; he uses his readers' awareness of hierarchy as a theme of his pastoral hypotexts to sustain a theme of social status throughout his Letters and to order his four books according to their protagonists' position in the hierarchy. His relocation of ‘Idylls’ to a Classical Attic setting, and transposition into the Sophistic Atticizing prose valued by contemporary authors, follows up Longus' attempt to reclaim the pastoral tradition from Virgil for Greek literature. Menander is proposed as an authorial figure for Alciphron in Letters 4.18–19.
Polynomial functors and polynomial monads
Authors: GAMBINO NICOLA , KOCK JOACHIM
Published: September 2012

We study polynomial functors over locally cartesian closed categories. After setting up the basic theory, we show how polynomial functors assemble into a double category, in fact a framed bicategory. We show that the free monad on a polynomial endofunctor is polynomial. The relationship with operads and other related notions is explored.
Adversarial scheduling in discrete models of social dynamics
Authors: ISTRATE GABRIEL , MARATHE MADHAV V. , RAVI S. S.
Published: September 2012

In this paper we advocate the study of discrete models of social dynamics underadversarial scheduling. The approach we propose forms part of a foundational basis for agenerative approach to social science(Epstein 2007). We highlight the feasibility of the adversarial scheduling approach by using it to study thePrisoners's Dilemma Game with Pavlov update, a dynamics that has already been investigated under random update in Kittock (1994), Dyeret al. (2002), Mossel and Roch (2006) and Dyer and Velumailum (2011). The model is specified by letting players at the nodes of an underlying graphGrepeatedly play the Prisoner's Dilemma against their neighbours. The players adapt their strategies based on the past behaviour of their opponents by applying the so-called win–stay lose–shift strategy. With random scheduling, starting from any initial configuration, the system reaches the fixed point in which all players cooperate with high probability. On the other hand, under adversarial scheduling the following results hold:

—

A scheduler that can selectbothgame participants can preclude the system from reaching the unique fixed point on most graph topologies.

—

A non-adaptive scheduler that is only allowed to chooseoneof the participants is no more powerful than a random scheduler. With this restriction, even an adaptive scheduler is not significantly more powerful than the random scheduler, provided it is ‘reasonably fair’.
Intersectoral labor mobility and deforestation in Ghana
Authors: Owusu Victor , Fosu K. Yerfi , Burger Kees
Published: September 2012

This paper quantifies the effects of the determinants of intersectoral labor mobility and the effect of intersectoral labor mobility on deforestation in Ghana over the period 1970–2008. A cointegration and error correction modeling approach is employed. The empirical results show that labor mobility from the agricultural to the non-agricultural sector exerts negative effects on deforestation in Ghana in the long run and short run. Relative agricultural income exerts a significant negative effect on intersectoral labor mobility in the long run. Deforestation is influenced positively by population pressure, the price of fertilizer and rainfall, whereas access to irrigation infrastructure exerts a negative effect in the long run. In the short run, real producer prices of cocoa and maize exert significant positive effects on deforestation whereas access to irrigation infrastructure exerts a negative significant effect. Fruitful policy recommendations based on the empirical magnitudes and directions of these effects are made in this paper.
The Bilingual Language Interaction Network for Comprehension of Speech
Authors: SHOOK ANTHONY , MARIAN VIORICA
Published: September 2012

During speech comprehension, bilinguals co-activate both of their languages, resulting in cross-linguistic interaction at various levels of processing. This interaction has important consequences for both the structure of the language system and the mechanisms by which the system processes spoken language. Using computational modeling, we can examine how cross-linguistic interaction affects language processing in a controlled, simulated environment. Here we present a connectionist model of bilingual language processing, the Bilingual Language Interaction Network for Comprehension of Speech (BLINCS), wherein interconnected levels of processing are created using dynamic, self-organizing maps. BLINCS can account for a variety of psycholinguistic phenomena, including cross-linguistic interaction at and across multiple levels of processing, cognate facilitation effects, and audio-visual integration during speech comprehension. The model also provides a way to separate two languages without requiring a global language-identification system. We conclude that BLINCS serves as a promising new model of bilingual spoken language comprehension.
Role of diatoms in nickel biogeochemistry in the ocean
Authors: Twining Benjamin S. , Baines Stephen B. , Vogt Stefan , Nelson David M.
Published: September 2012

Dissolved nickel (Ni) typically displays a ‘nutrient‐like’ vertical profile in the ocean, with lower concentrations in surface waters and higher concentrations in deep waters, similar to other micronutrient metals such as iron and zinc. Vertical profiles of Ni show particular similarities to profiles of the macronutrients phosphate and silicic acid, suggesting that diatoms play an important role in mediating the vertical distribution of this metal. We performed synchrotron x‐ray fluorescence (SXRF) analysis on individual phytoplankton cells collected from stations in the equatorial Pacific Ocean and from nutrient‐addition incubation experiments conducted on the same cruise. Diatoms were enriched in Ni twofold to fivefold relative to picoplankton and flagellated cells. Changes in cellular quotas of Si, P and Ni observed in diatoms growing in response to Fe and Si additions were used to estimate the Ni:P (0.52 ± 0.10 mmol/mol) and Ni:Si (28 ± 13 μmol/mol) ratios of internal biomass and the frustule, respectively. Elevated internal Ni:P suggests a heightened role for urease or the Ni isoform of superoxide dismutase in diatoms (similar to cyanobacteria), while Ni associated with the frustule appears to contribute an additional 50% of cellular Ni found in the diatoms. The derived Ni:Si ratio for frustule material is comparable to Ni:Si ratios in published nutrient profiles, confirming the dominant role that diatoms play in ocean Ni biogeochemistry. While a molecular explanation for the association of Ni with frustules remains to be determined, this study demonstrates the unique biogeochemical insight that can be gained from microanalytical element analysis.
Physical controls and predictability of stream hyporheic flow evaluated with a multiscale model
Authors: Stonedahl Susa H. , Harvey Judson W. , Detty Joel , Aubeneau Antoine , Packman Aaron I.
Published: September 2012

Improved predictions of hyporheic exchange based on easily measured physical variables are needed to improve assessment of solute transport and reaction processes in watersheds. Here we compare physically based model predictions for an Indiana stream with stream tracer results interpreted using the Transient Storage Model (TSM). We parameterized the physically based, Multiscale Model (MSM) of stream‐groundwater interactions with measured stream planform and discharge, stream velocity, streambed hydraulic conductivity and porosity, and topography of the streambed at distinct spatial scales (i.e., ripple, bar, and reach scales). We predicted hyporheic exchange fluxes and hyporheic residence times using the MSM. A Continuous Time Random Walk (CTRW) model was used to convert the MSM output into predictions of in stream solute transport, which we compared with field observations and TSM parameters obtained by fitting solute transport data. MSM simulations indicated that surface‐subsurface exchange through smaller topographic features such as ripples was much faster than exchange through larger topographic features such as bars. However, hyporheic exchange varies nonlinearly with groundwater discharge owing to interactions between flows induced at different topographic scales. MSM simulations showed that groundwater discharge significantly decreased both the volume of water entering the subsurface and the time it spent in the subsurface. The MSM also characterized longer timescales of exchange than were observed by the tracer‐injection approach. The tracer data, and corresponding TSM fits, were limited by tracer measurement sensitivity and uncertainty in estimates of background tracer concentrations. Our results indicate that rates and patterns of hyporheic exchange are strongly influenced by a continuum of surface‐subsurface hydrologic interactions over a wide range of spatial and temporal scales rather than discrete processes.
The 2011 La Niña: So strong, the oceans fell
Authors: Boening Carmen , Willis Josh K. , Landerer Felix W. , Nerem R. Steven , Fasullo John
Published: September 2012

Global mean sea level (GMSL) dropped by 5 mm between the beginning of 2010 and mid 2011. This drop occurred despite the background rate of rise, 3 mm per year, which dominates most of the 18‐year record observed by satellite altimeters. Using a combination of satellite andin situdata, we show that the decline in ocean mass, which explains the sea level drop, coincides with an equivalent increase in terrestrial water storage, primarily over Australia, northern South America, and Southeast Asia. This temporary shift of water from the ocean to land is closely related to the transition from El Niño conditions in 2009/10 to a strong 2010/11 La Niña, which affected precipitation patterns world‐wide.
Cluster observations of band‐limited Pc 1 waves associated with streaming H+ and O+ions in the high‐altitude plasma mantle
Authors: Engebretson M. J. , Kahlstorf C. R. G. , Murr D. L. , Posch J. L. , Keiling A. , Lavraud B. , Rème H. , Lessard M. R. , Kim E.‐H. , Johnson J. R. , Dombeck J. , Grison B. , Robert P. , Glassmeier K.‐H. , Décréau P. M. E.
Published: September 2012

Bursts of band‐limited Pc 1 waves (0.2 to ∼1.0 Hz) with normalized frequency f/fH+∼ 0.5 have been observed by the Cluster spacecraft during many passes through the high‐latitude plasma mantle. These transverse, left‐hand polarized waves are associated with regions of H+ and O+ ions streaming away from Earth along magnetic field lines at the same velocity (∼140 km/s). Waves were observed only when H+fluxes increased by factors of 10–1000 and energies of both ion species increased by factors of up to 10. We present two satellite‐ground conjunctions to demonstrate the high latitude localization of these waves and their ability to reach the polar ionosphere and two extended examples of waves and associated ion distribution functions near the southern dusk flank magnetopause. We also present the results of a search for all such events during Cluster's 2002 and 2003 passages through the magnetotail, with orbital precession covering dawn to dusk on Earth's night side (June through December). A total of 46 events (band‐limited Pc 1–2 waves accompanied by a sustained population of streaming H+ and O+ ions, separated by at least 12 min) were observed on 29 days. The waves were generally associated with intervals of southward IMF Bz and/or large IMF By (times of active cusp reconnection), and often but not always occurred during the main phase or early recovery phase of magnetic storms. Analysis of selected events shows that the waves are associated with large H+ temperature anisotropy, and that the waves propagate opposite to the direction of the streaming ions. A wave instability analysis using the WHAMP code confirms that the generation of these waves, via the ion cyclotron instability, is basically consistent with known physics. Their extended region of wave growth is likely, however, to reach tailward significantly beyond the Cluster orbit.
Spatial and temporal variations in Greenland glacial‐earthquake activity, 1993–2010
Authors: Veitch Stephen A. , Nettles Meredith
Published: September 2012

Glacial earthquakes are anomalous earthquakes associated with large ice‐loss events occurring at marine‐terminating glaciers, primarily in Greenland. They are detectable teleseismically, and a proper understanding of the source mechanism may provide a remote‐sensing tool to complement glaciological observations of these large outlet glaciers. We model teleseismic surface‐wave waveforms to obtain locations and centroid–single‐force source parameters for 121 glacial earthquakes occurring in Greenland during the period 2006–2010. We combine these results with those obtained by previous workers to analyze spatial and temporal trends in glacial‐earthquake occurrence over the 18‐year period from 1993–2010. We also examine earthquake occurrence at six individual glaciers, comparing the earthquake record to independently obtained observations of glacier change. Our findings confirm the inference that glacial‐earthquake seismogenesis occurs through the capsize of large, newly calved icebergs. We find a close correspondence between episodes of glacier retreat, thinning, and acceleration and the timing of glacial earthquakes, and document the northward progression of glacial earthquakes on Greenland's west coast over the 18‐year observing period. Our results also show that glacial earthquakes occur when the termini of the source glaciers are very close to the glacier grounding line, i.e., when the glaciers are grounded or nearly grounded.
Organic carbon transformations in high-Arctic peat soils: key functions and microorganisms
Authors: Tveit Alexander , Schwacke Rainer , Svenning Mette M , Urich Tim
Published: September 2012

A substantial part of the Earths’ soil organic carbon (SOC) is stored in Arctic permafrost peatlands, which represent large potential sources for increased emissions of the greenhouse gases CH4 and CO2 in a warming climate. The microbial communities and their genetic repertoire involved in the breakdown and mineralisation of SOC in these soils are, however, poorly understood. In this study, we applied a combined metagenomic and metatranscriptomic approach on two Arctic peat soils to investigate the identity and the gene pool of the microbiota driving the SOC degradation in the seasonally thawed active layers. A large and diverse set of genes encoding plant polymer-degrading enzymes was found, comparable to microbiotas from temperate and subtropical soils. This indicates that the metabolic potential for SOC degradation in Arctic peat is not different from that of other climatic zones. The majority of these genes were assigned to three bacterial phyla, Actinobacteria, Verrucomicrobia and Bacteroidetes. Anaerobic metabolic pathways and the fraction of methanogenic archaea increased with peat depth, evident for a gradual transition from aerobic to anaerobic lifestyles. A population of CH4-oxidising bacteria closely related to Methylobacter tundripaludum was the dominating active group of methanotrophs. Based on the in-depth characterisation of the microbes and their genes, we conclude that these Arctic peat soils will turn into CO2 sources owing to increased active layer depth and prolonged growing season. However, the extent of future CH4 emissions will critically depend on the response of the methanotrophic bacteria.
Mapping histamine H4receptor–ligand binding modes
Authors: Schultes Sabine , Nijmeijer Saskia , Engelhardt Harald , Kooistra Albert J. , Vischer Henry F. , de Esch Iwan J. P. , Haaksma Eric E. J. , Leurs Rob , de Graaf Chris
Published: September 2012

Computational prediction of ligand binding modes in G protein-coupled receptors (GPCRs) remains a challenging task. Systematic consideration of different protein modelling templates, ligand binding poses, and ligand protonation states in extensive molecular dynamics (MD) simulation studies enabled the prediction of ligand-specific mutation effects in the histamine H4receptor, a key player in inflammation.
Inductance and near fields of a loop antenna in a cold magnetoplasma in the whistler frequency band
Authors: Gushchin M. E. , Zaboronkova T. M. , Krafft C. , Korobkov S. V. , Kostrov A. V.
Published: September 2012

The influence of a magnetoplasma on the inductance of a circular loop antenna oriented perpendicular to the ambient static magnetic field and operated in the whistler frequency band is studied. Based on a strict electrodynamic approach, the analytical treatment of the antenna reactance is performed for a uniform rf current distribution along the antenna wire. Calculations are made for plasma parameters and operating frequencies typical for active ionospheric experiments and laboratory rf (helicon) sources of dense magnetized plasmas. It is shown that the plasma influence on the inductance of the loop antenna remains relatively weak, even for antennas with dimensions close to half of the longitudinal whistler wavelength, when the rf field distribution in the antenna near zone is strongly different from that in vacuum. The theoretical predictions are confirmed by measurements performed on the large KROT plasma device. The results obtained are of crucial importance for the preparation of active ionospheric experiments and for the matching of loop antennas used in laboratory rf sources of dense magnetized plasmas.
Molecular dynamics study of free energy of transfer of alcohol and amine from water phase to the micelle by thermodynamic integration method
Authors: Fujimoto K. , Yoshii N. , Okazaki S.
Published: September 2012

Free energy of transfer of methylamine, octylamine, methanol, and octanol from water phase to sodium dodecyl sulfate (SDS) micelle has been calculated using thermodynamic integration method combined with molecular dynamics calculations. Together with the results for alkanes obtained in our previous study [K. Fujimoto, N. Yoshii, and S. Okazaki, J. Chem. Phys. 133, 074511 (2010)]10.1063/1.3469772, the effect of polar group on the partition of hydrophilic solutes between water phase and the micelle has been investigated in detail at a molecular level. The calculations showed that the molecules with octyl group are more stable in the SDS micelle than in the water phase due to their hydrophobicity of long alkyl chain. In contrast, methanol and methylamine are stable in the water phase as well as in the micelle because of their high hydrophilicity. The spatial distribution of methylamine, octylamine, methanol, and octanol has also been evaluated as a function of the distance, R, from the center of mass of SDS micelle to the solutes. The distribution shows that the methylamine molecule is adsorbed on the SDS micelle surface, while the methanol molecule is delocalized among the whole system, i.e., in the water phase, on the surface of the micelle, and in the hydrophobic core of the micelle. The octylamine and octanol molecules are solubilized in the SDS micelle with palisade layer structure and are not found in the water phase.
Electric dipole (hyper)polarizabilities of spatially confined LiH molecule
Authors: Góra Robert W. , Zaleśny Robert , Kozłowska Justyna , Naciążek Paulina , Roztoczyńska Agnieszka , Strasburger Krzysztof , Bartkowiak Wojciech
Published: September 2012

In this study we report on the electronic contributions to the linear and nonlinear static electronic electric dipole properties, namely the dipole moment (μ), the polarizability (α), and the first-hyperpolarizability (β), of spatially confined LiH molecule in its ground X 1Σ+ state. The finite-field technique is applied to estimate the corresponding energy and dipole moment derivatives with respect to external electric field. Various forms of confining potential, of either spherical or cylindrical symmetry, are included in the Hamiltonian in the form of one-electron operator. The computations are performed at several levels of approximation including the coupled-cluster methods as well as multi-configurational (full configuration interaction) and explicitly correlated Gaussian wavefunctions. The performance of Kohn–Sham density functional theory for the selected exchange-correlation functionals is also discussed. In general, the orbital compression effects lead to a substantial reduction in all the studied properties regardless of the symmetry of confining potential, however, the rate of this reduction varies depending on the type of applied potential. Only in the case of dipole moment under a cylindrical confinement a gradual increase of its magnitude is observed.
A molecular dynamics study of dipolar vortices in strongly coupled Yukawa liquids
Authors: J. Ashwin , Ganesh R.
Published: September 2012

Coherent dipolar vortices are a universal outcome of injecting linear momentum into a liquid. Once formed, these dipolar vortices can transport mass and momentum over large length scales and are hence a subject matter of intense research work. Using “first principles” classical molecular dynamics simulations, we report for the first time, formation and collision of dipolar vortices in a two-dimensional prototype strongly coupled liquid, namely, the Yukawa liquid. A dipolar vortex is seen to emerge from the self-organization of a sub-sonic jet profile. This dipole is seen to be very robust and, in general, shows a nonlinear relationship between vorticity and stream function. Starting from two jets injecting linear momentum in mutually opposite directions, we report on the centered head-on collisions between two dipolar vortices. Effect of background friction on the dipole evolution is investigated.
Theory and simulation of organic solar cell model compounds: How packing and morphology determine the electronic conductivity
Authors: Lampe Benjamin , Koslowski Thorsten
Published: September 2012

We approach the electronic conductivity of simple models of organic solar cells containing linear and branched αα′-oligothiophenes and buckminsterfullerene. Close-packed model geometries are generated using a Monte Carlo method, this procedure is verified making use of an analogue model. The electronic structure is described by an extended Su-Schrieffer-Heeger Hamiltonian, the resulting potential energy surfaces relevant to charge transfer can be analyzed using Marcus’ theory, leading to local and—via Kirchhoff's rule—global conductivities for uniform oligothiophene and fullerene systems and their mixtures. Dense fullerene systems or subsystems always exhibit a conductivity in excess of 100 S/cm. In contrast, oligothiophenes show a comparable conductivity only for uniform, well-ordered arrangements of layers. Branched oligomers show only a slight improvement over linear oligothiophenes. Our results support the bulk heterojunction approach as a design principle of organic solar cells from a theoretical perspective.
Growth regimes during homoepitaxial growth of GaN by ammonia molecular beam epitaxy
Authors: Corrion A. L. , Wu F. , Speck J. S.
Published: September 2012

c-plane GaN films were grown by ammonia molecular beam epitaxy on metal-organic chemical vapor deposition templates for a wide range of NH3:Ga flux ratios and growth temperatures, and the resulting films were characterized using atomic force microscopy, reflection high-energy electron diffraction, and transmission electron microscopy. Three distinct nitrogen-rich growth regimes—unstable layer-by-layer, quasi-stable step flow, and dislocation-mediated pitting—were identified based on the growth mode and film properties. In addition, step flow growth was observed under conditions of gallium droplet accumulation. The results indicate the existence of two regimes for step-flow growth of GaN by ammonia MBE—both gallium-rich and nitrogen-rich. Growth mode instabilities and mound formation were observed and are discussed in the context of a step-edge energy barrier to adatom diffusion over a terrace.
Strain-less directed self-assembly of Si nanocrystals on patterned SiO2 substrate
Authors: Ren Jingjian , Hu Hao , Liu Feng , Chu Sheng , Liu Jianlin
Published: September 2012

Strain induced self-assembled Stranski-Krastanov growth of semiconductor islands on patterned substrate has shown great improvement of island size uniformity and spatial order. Here, we show self-assembled Volmer-Weber (V-W) growth of Si nanocrystals (NCs) on patterned SiO2 substrate via traditional chemical vapor deposition method under certain experimental configurations, induced by surface/interface energy competition without strain. A simplified two-dimensional theoretical model is developed to elucidate V-W island nucleation on the pattern substrate with varied morphologies, which shows good consistency with the experimental results. Our studies provide a general guidance for directing the growth and self-assembly of NCs on non-planar oxide substrates.
Importance of excitonic effects and the question of internal electric fields in stacking faults and crystal phase quantum discs: The model-case of GaN
Authors: Corfdir Pierre , Lefebvre Pierre
Published: September 2012

We compute using envelope function calculations the energy and the oscillator strength of excitons in zinc-blende/wurtzite quantum wells (QWs), such as those that appear in many examples of semiconductor nanowires, and in basal plane stacking faults (BSFs). We address specifically the model-case of GaN. In addition to the electron-hole Coulomb interaction, we account for the quantum-confined Stark effect. We demonstrate that despite the type-II band alignment at the zinc-blende/wurtzite interfaces, a significant binding and a rather strong oscillator strength are preserved by excitonic effects. When adjacent crystal phase QWs are coupled together, we compute increased as well as decreased exciton oscillator strength with respect to the single QW case, depending on the QW-QW coupling scheme. Comparing the results of our calculations with available data, we finally conclude in favor of the absence of built-in electric fields perpendicular to the BSF planes.
Composition, nanostructure, and optical properties of silver and silver-copper lusters
Authors: Pradell Trinitat , Pavlov Radostin S. , Carolina Gutiérrez Patricia , Climent-Font Aurelio , Molera Judit
Published: September 2012

Lusters are composite thin layers of coinage metal nanoparticles in glass displaying peculiar optical properties and obtained by a process involving ionic exchange, diffusion, and crystallization. In particular, the origin of the high reflectance (golden-shine) shown by those layers has been subject of some discussion. It has been attributed to either the presence of larger particles, thinner multiple layers or higher volume fraction of nanoparticles. The object of this paper is to clarify this for which a set of laboratory designed lusters are analysed by Rutherford backscattering spectroscopy, transmission electron microscopy, x-ray diffraction, and ultraviolet-visible spectroscopy. Model calculations and numerical simulations using the finite difference time domain method were also performed to evaluate the optical properties. Finally, the correlation between synthesis conditions, nanostructure, and optical properties is obtained for these materials.