bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of near-surface and volume real structure on the electronic properties of SrTiO3 MIM structures
Authors: Seibt J. , Hanzig F. , Strohmeyer R. , Stoecker H. , Himcinschi C. , Abendroth B. , Meyer D. C.
Published: September 2011

Perovskite-type transition metal oxides have great potential as storage material in resistive random-access memory (RRAM) devices. Typical non-volatile memory cells are realized in metal-insulator-metal (MIM) stacks with insulator thicknesses of few nanometers. We report on the investigation of single-crystal SrTiO3 to understand the role of volume and interface real structure for the electrical conductivity in such materials. Conductivity in SrTiO3 single crystals was established by a reducing high vacuum (HV) annealing introducing charged oxygen vacancies acting as donor centers. Titanium electrodes are evaporated on both crystal faces to obtain an MIM element.
The Absorption of Diamondoids from Time-dependent Density Functional Calculations
Authors: Vörös Márton , Demjén Tamás , Gali Adam
Published: September 2011

Diamondoids are small diamond nanocrystals with perfect hydrogenated surfaces. Recent absorption measurements showed that the spectrum of diamondoids exhibit features that are not understood from the theoretical point of view, e.g. optical gaps are only slightly larger than the gap of bulk diamond which runs against the quantum confinement effect. Previous calcula-tions, even beyond standard density functional theory (DFT), failed to obtain the experimental optical gaps (Eg) of diamondoids. We show that all-electron time-dependent DFT (TD-DFT) calculations including the PBE0 hybrid functional in the TD-DFT kernel are able to provide quantitatively accurate results. Our calculations demonstrate that Rydberg transitions govern the low energy part of the absorption spectrum, even for relatively large nanodiamonds result-ing in low Eg. Since the optical gap of these diamondoids lies in the ultraviolet spectral re-gion, we investigated whether simple adsorbates of the surface are able to shift the gap towards the infrared region. We found that a double bonded sulfur atom at the surface results in a sub-stantial gap reduction.
Ferromagnetism in undoped semiconductors
Authors: Ma Yandong , Dai Ying , Huang Baibiao
Published: September 2011

The so-called “d0” magnetism observed in semiconductors, which is not caused by partially filled d orbitals, has challenged our conventional understanding on the origin of magnetism. One class of semiconductor materials showing d0 ferromagnetism is undoped oxides and nitrides. Here, we review the ferromagnetic properties of undoped GaN and MgO based on our recent investigations. It is revealed that the room-temperature ferromagnetism originates from the anion dangling bonds associated with the surface cation-vacancies. And the magnetism of ferromagnetic coupling between the vacancy induced local magnetic moment by through-bond spin polarization in undoped semiconductors is reviewed according to our works.
Magnetic Properties of Polar ZnO Surfaces from Ab-initio Calculations
Authors: Fischer Guntram , Sanchez Nadiezhda , Adeagbo Waheed A. , Lüders Martin , Szotek Zdzislawa , Temmerman Walter , Ernst Arthur , Hergert Wolfram , Muñoz M. Carmen
Published: September 2011

We have studied the effect that applying self-interaction correction (SIC) to oxygen p orbitals has on the magnetic moment formation of three polar ZnO surfaces; all of them being oxygen terminated. For these investigations we have used a multi-code approach. This has allowed us, on the one hand, to relax the surface structure using the pseudopotential code SIESTA. On the other hand, by using the obtained relaxed structures for calculations within the KKR Green’s function formalism, we have been able to apply SIC and use the magnetic force theorem for calculating Heisenberg exchange parameters. The latter contain information about both the strength of the interaction and the interaction mechanism.

Our calculations show that all three surfaces are magnetic. In addition, we find that applying SIC is necessary to correctly describe the top oxygen atom of the (0001)-t and (0001)-h surfaces.
Isocyanate-Derived Organic Aerogels: Polyureas, Polyimides, Polyamides
Authors: Leventis Nicholas , Sotiriou-Leventis Chariklia , Chandrasekaran Naveen , Mulik Sudhir , Chidambareswarapattar Chakkaravarthy , Sadekar Anand , Mohite Dhairyashil , Mahadik Shruti S. , Larimore Zachary J. , Lu Hongbing , Churu Gitogo , Mang Joseph T.
Published: September 2011

We describe organic aerogels derived from multifunctional isocyanates through reaction with water (polyureas), acid andydrides (polyimides) and carboxylic acids (polyamides). All processes are invariably single-step, one-pot and take place at room or slightly elevated temperatures. The resulting materials are robust, their density may vary over a very wide range and their nanomorphology can be either particulate or fibrous, but in all cases they all consist of similarly sized primary particles.
Polar-fluoropolymer Blends for High Energy Density Low Loss Capacitor Applications
Authors: Wu Shan , Lin Minren , Lu David S-G. , Zhang Qiming
Published: September 2011

Besides energy density, the electric loss at high electric fields is another major concern for many capacitor applications. This paper presents recent works in developing high energy density low loss polymer capacitors. In order to reduce the dielectric loss while maintaining high energy density in poly(vinylidene fluoride-hexafluoropropylene) P(VDF-HFP) and P(VDF-CTFE) (CTFE: Chlorotrifluoroethylene) based polymers, a polymer blend approach was investigated. We show that by blending P(VDF-CTFE) with a proper low loss polymer such as poly(ethylene- chlorotrifluoroethylene) (ECTFE) can lead to marked improvement in the loss of dielectric films. In this study, P(VDF-CTFE) blends films with different wt% of ECTFE have been examined to find a balance between dielectric constant and the loss. In addition, crosslink in the blends has been employed to further improve the dielectric performance of the blends. The results indicate that these blends exhibit an excellent performance: relatively high dielectric constant (~ 6~7) and low loss (~ 0.01) at 1 kHz. For the crosslink blend films, the high field loss is reduced to below 5% with a discharged energy density 4.3 J/cm3 under a field of 300 MV/m.
Thermo-mechanical Behavior of (Meth)Acrylate Shape-Memory Polymer Networks
Authors: Frick Carl P. , Lakhera Nishant , Yakacki Christopher M.
Published: September 2011

Our overall approach is based on developing a photocrosslinkable polymer network with a favorable shape-memory response, using polymer chemistry and crosslinking density to control thermo-mechanical properties. Three polymer networks were created and thermo-mechanically tested, each from tert-Butyl acrylate linear builder co-polymerized with a poly(ethylene glycol) dimethacrylate cross-linker. By systematically altering the molecular weight and the weight fraction of the cross-linker, it was possible to create three polymers that exhibited the same glass transition temperature, but varied by almost an order of magnitude in rubbery modulus. Therefore, the mechanical stiffness could be tailored to suit a given application. Recovery behavior of the polymers was characterized over a range of deformation temperatures. It has been implicitly assumed a linear relationship between Free-Strain (i.e. no actuation force) and Fixed-Stress (i.e. maximum actuation force), however, this has never been confirmed experimentally. The energy per unit volume performed by the shape-memory polymer was quantified, and observed to be a function of strain recovered. The maximum recoverable work was shown to increase with cross-linking density, although the overall efficiency is similar for all materials tested.
Development of a dual growth factor loaded biodegradable hydrogel and its evaluation on osteoblast differentiation in vitro
Authors: Dyondi Deepti , Webster Thomas J , Banerjee Rinti
Published: September 2011

Hydrogels with their tunable properties are attractive candidates for developing tissue engineering scaffolds for various applications (including bone and cartilage). The current work involved studying the synergistic effect of basic fibroblast growth factor (bFGF) and platelet derived growth factor BB (PDGF-BB) entrapped within injectable porous gels for bone regeneration applications. An in situ gelling system was developed using bacterial polysaccharides gellan and xanthan gum by temperature and ionic gelation with Ca+2. After the initial characterization of the hydrogels, a dual growth factor release system was developed wherein growth factors were encapsulated within chitosan nanoparticles embedded in the gels as well as directly within the gel. The hydrogel structure was characterized by SEM and TEM and in vitro growth factor release studies showed a slow release profile in PBS. Further, human fetal osteoblasts were entrapped within the hydrogel and a 21 day osteoblast differentiation study was conducted. An improvement in osteoblast total protein synthesis and collagen content was observed by day 21 compared to control gels without growth factors. Although further evaluation regarding mechanical properties and expression of osteogenic differentiation marker genes will be necessary, the present study suggests that injectable scaffolds can be used for the delivery of multiple growth promoting agents to support osteoblast differentiation.
Low Energy Ne Scattering Spectroscopy for Insulators, and Materials in the Electric/Magnetic Fields
Authors: Umezawa Kenji , Nakanishi Shigemitsu , Hayashi Hideki , Higashitsutsumi Hideaki , Nagasawa Hiroki , Narihiro Eisuke , Ogai Keiko
Published: September 2011

This study describes a low-energy atom scattering system that was combined with a time-of-flight spectrometer for insulator surface structural analysis. We show one example. MgO(001) crystal was used to study the surface analysis technique and is illustrated here. Insulator surface structure is difficult to study because of the charging effects during electron or ion-beam bombardment. Nevertheless, structural analysis of insulator surfaces is very important in fundamental research as well as in technology fields.
Effect of Oxygen Pressure on the Initial Oxidation Behavior of Cu and Cu-Au Alloys
Authors: Luo Langli , Kang Yihong , Liu Zhenyu , Yang Judith C , Zhou Guangwen
Published: September 2011

A wide information gap exists between our present atomic-scale knowledge of metal oxidation derived from conventional ultrahigh vacuum (UHV) surface science experiments and the oxidation mechanisms obtained from the growth of bulk oxide thin films under technologically relevant realistic (or near-) atmospheric conditions. To bridge this pressure gap, we present an in-situ transmission electron microscopy (TEM) study of the initial oxidation stage of Cu(100) and Cu-Au(100) surfaces where the oxygen partial pressure varies from 5x10-4 to 150 Torr. For Cu(100), with increasing oxygen partial pressure (pO2), the nucleation density of the oxide islands increases and so does the growth rate of the oxide islands. As the pO2 continues to increase, a transition from epitaxial cube-on-cube Cu2O islands to randomly oriented oxide islands is observed. A kinetic model based on the classic heterogeneous nucleation theory is developed to explain the effect of oxygen partial pressure on the oxide orientation. It is shown that such a transition in the oxide nucleation orientation is related to the effect of oxygen pressure on the nucleation barrier and atom collision rate. The Cu-Au(111) alloy revealed the same oxygen pressure dependency of the oxide nucleation orientation as pure Cu oxidation.
Effect of Buffer Structure on the Performance of a-Si:H/a-Si:H Tandem Solar Cells
Authors: Hsu C.H. , Lee C.Y. , Cheng P.H. , Chuang C.K. , Tsai C.C.
Published: September 2011

The study focuses on the influence of the hydrogenated amorphous silicon carbide (a-SiC:H) buffer layer in hydrogenated amorphous silicon (a-Si:H) single-junction and tandem thin-film solar cells. By increasing the undoped a-SiC:H buffer layer thickness from 6nm to 12nm, the JSC in single-junction cell was significantly improved, and the efficiency was increased by 4.5%. The buffer layer also effectively improves the efficiency of the a-Si:H/a-Si:H tandem cells by 7% as a result of the increase in open-circuit voltage (VOC) and short-circuit current (JSC). Although the bottom cell absorbs less short-wavelength photons, the wider-bandgap doped and buffer layers were still necessary for improving the cell efficiency. Presumably, this is because these wider-bandgap layers allow more photons to reach the bottom cell. Also, they can reduce interface recombination.
The Use of Ammonium Carbamate as a High Energy Density Thermal Energy Storage Material
Authors: Schmidt Joel E. , Dudis Douglas S. , Miller Douglas J.
Published: September 2011

Phase change materials (PCMs) often have higher specific energy storage capacities at elevated temperatures. Thermal management (TM) systems capable of handling high heat fluxes in the temperature range from 20–100°C are necessary but lacking. State of the art PCMs in this temperature range are usually paraffin waxes with energy densities on the order of a few hundred kJ/kg or ice slurries with energy densities of the same magnitude. However, for applications where system weight and size are limited, it is necessary to improve this energy density by at least an order of magnitude. The compound ammonium carbamate, [NH4][H2NCOO], is a solid formed from the reaction of ammonia and carbon dioxide which endothermically decomposes back to CO2 and NH3 in the temperature range 20-100°C with an enthalpy of decomposition of ∼2,000 kJ/kg. Various methods to use this material for TM of low-grade, high-flux heat have been evaluated including: bare powder, thermally conductive carbon foams, thermally conductive metal foams, hydrocarbon based slurries, and a slurry in ethylene glycol or propylene glycol. A slurry in glycol is a promising system medium for enhancing heat and mass transfer for TM. Progress on material and system characterization is reported.
Investigation on Phase Change Behaviors of Si-Sb-Te Alloy: The Effect of Tellurium Segregation
Authors: Zhou Xilin , Wu Liangcai , Song Zhitang , Rao Feng , Ren Kun , Cheng Yan , Liu Bo , Yao Dongning , Feng Songlin , Chen Bomy
Published: September 2011

In this study, novel Si2Sb2Te6 phase change material is investigated in detail for the phase change memory application using transmission electron microscopy and X-ray photoelectron spectroscopy. The phenomenon that Te diffuses to the film surface during phase switching and successively evaporates out has been confirmed. The phase change memory cells employing Si2Sb2Te6 and Si3Sb2Te3 materials are fabricated and programmed. For the Si2Sb2Te6-based cell a data endurance of 5×105 cycles is achieved with a failure mode resembling reset stuck, which can be attributed to the migration of Tellurium during the operation cycles. It means that a thermally stable material system of SixSb2Te3 is preferred for the PCM applications.
Evidence and Characterization of Crystallographic Defect and Material Quality after SLIM-Cut Process
Authors: Masolin Alex , Vaes Jan , Dross Frederic , Martini Roberto , Rodriguez Amaia Pesquera , Poortmans Jef , Mertens Robert
Published: September 2011

The SLIM-Cut process is a kerf-free wafering technique to obtain silicon substrates as thin as 50μm. The quality of the resulting material must be assessed to ensure that this innovative Si-foil approach does not jeopardize the potential efficiency of the final solar cell in terms of electronic activity, defect density and location. For that reason, we performed Microwave-Detected Photoconductance Decay (MW-PCD), Deep-Level Transient Spectroscopy (DLTS) and optical inspections after defect etching of the foils surface. Analyses indicate that SLIM-Cut generates crystallographic defects which create deep level traps that have a negative impact on the lifetime of the silicon foil. Nonetheless, a decrease of the thermal budget will lead to a reduction of plasticity and hence lower the amount of defects and increase the foil quality.
Optically Induced Sub-Wavelength Transient Apertures in Sb-Te Based Films
Authors: Simpson Robert E. , Fons Paul J. , Kolobov Alexander V. , Wang Xiomin , Tominaga Junji
Published: September 2011

The origin of sub-diffraction-limit apertures in Sb-based thin films is discussed. Electromagnetic energy can be channeled by these apertures thus allowing near-field focussing- the Super-RENS effect. The aperture formation within Sb, Sb2Te3, Sb2Te, SbTe and Ge2Sb2Te5 is investigated by time resolved optical pump-probe techniques and found to occur without melting. Density functional calculations have shown that these materials exhibit a thresholdlike change in their optical properties below their melting temperatures. The threshold is shown to be a consequence of thermally induced misalignment of p-orbital bonds. It is the non-linearity of this process that leads to the formation of the sub-diffraction-limit apertures.
Electroluminescence Properties of Eu-doped GaN-based Light-emitting Diodes Grown by Organometallic Vapor Phase Epitaxy
Authors: Nishikawa Atsushi , Furukawa Naoki , Lee Dong-gun , Kawabata Kosuke , Matsuno Takanori , Terai Yoshikazu , Fujiwara Yasufumi
Published: September 2011

We investigated the electroluminescence (EL) properties of Eu-doped GaN-based light-emitting diodes (LEDs) grown by organometallic vapor phase epitaxy (OMVPE). The thickness of the active layer was varied to increase the light output power. With increasing the active layer thickness, the light output power monotonically increased. The maximum light output power of 50 μW was obtained for an active layer thickness of 900 nm with an injected current of 20 mA, which is the highest value ever reported. The corresponding external quantum efficiency was 0.12%. The applied voltage for the LED operation also increased with the active layer thickness due to an increase in the resistance of the LED. Therefore, in terms of power efficiency, the optimized active layer thickness was around 600 nm. These results indicate that the optimization of the LED structure would effectively improve the luminescence properties.
Ultraviolet Light Emitting Devices Using AlGdN
Authors: Kita Takashi , Kitayama Shinya , Ishihara Tsuguo , Izumi Hirokazu , Chigi Yoshitaka , Nishimoto Tetsuro , Tanaka Hiroyuki , Kobayashi Mikihiro
Published: September 2011

We developed ultra-violet field-emission devices using rare-earth nitrides of Al1-xGdxN grown by a reactive radio-frequency magnetron sputtering technique. The Al1-xGdxN phosphor film excited by high-energy electrons shows a resolution limited, narrow intra-orbital luminescence from Gd3+ ions at 318 nm. The devise characteristics depend on injected current and acceleration voltage, which were analyzed by considering multiple excitation process of injected high-energy electrons.
Estereótipos e essencialização de brancos e negros: um estudo comparativo
Authors: Pereira Marcos Emanoel , Álvaro José Luis , Oliveira Andréia C. , Dantas Gilcimar S.
Published: September 2011

O combate aos efeitos negativos dos estereótipos, dos preconceitos e da exclusão social é um problema recorrente da nossa época. Um dos maiores desafios enfrentados por quem se dedica a refletir acerca deste tema se refere ao papel desempenhado pelo raciocínio categórico essencialista. O objetivo principal do presente artigo é apresentar os resultados de um estudo sobre a essencialização da categoria social raça. O estudo contou com 101 participantes brasileiros e 138 espanhóis. Foi constatado um claro efeito do país no grau de essencialização, assim como foram obtidas evidências de que a essencialização sofreu o impacto da hegemonia da categoria. A análise das explicações adotadas pelos participantes permitiu concluir que, dentre as teorias implícitas, as causas internas foram adotadas com maior frequência, a história causal foi predominantemente utilizada para explicar as mudanças no comportamento e as pressões situacionais foram arroladas para explicar, preferencialmente, a estabilidade da conduta.
Estimativa de propriedades termofísicas em campo usando modelos de transferência de calor e umidade
Authors: Ordenes Martin , Guths Saulo , Lamberts Roberto
Published: September 2011

A condução de calor através dos componentes opacos da envoltória é um dos parâmetros que caracterizam o desempenho térmico das edificações e suas consequências em termos de consumo energético e conforto térmico. A envoltória pode ser descrita termicamente a partir de dois parâmetros: a condutividade térmica (λ); e a capacidade térmica volumétrica (ρ∙c). Estimar essas propriedades termofísicas em campo permite caracterizar elementos construtivos considerando aspectos como comportamento térmico em condições climáticas específicas, variação na qualidade de materiais, soluções locais de construção e desgaste de materiais. Este trabalho apresenta um método para estimar λ e ρ∙c em elementos homogêneos usando um teste não destrutivo que aproveita as oscilações naturais do clima. A temperatura e o calor superficial são medidos em uma amostra de concreto (com propriedades conhecidas) e os dados são tratados com uma técnica de processamento de sinal. A estimativa é executada com um modelo de transferência de calor e umidade integrado. As medições foram realizadas em seis dias durante um período de um mês, registrando dias com diferentes condições de céu, visando mostrar a importância da radiação solar como fonte de calor. Os resultados apresentaram uma diferença de 10-14% na estimativa das propriedades termofísicas.
Fator de visão do céu e intensidade de ilhas de calor na escala do pedestre
Authors: Souza Lea Cristina Lucas de , Tente Cezar Mecozzi , Giunta Mariene Benutti , Nakata Camila Mayumi
Published: September 2011

A falta de ferramentas disponíveis para a tomada de decisões no planejamento urbano baseado nas interações entre clima e cidade é um desafio para o arquiteto e para o urbanista. Apesar da existência de alguns modelos destinados a esse fim, as limitações para sua aplicação dificultam ainda mais o quadro. Procurando gerar informações que colaborem com essa área, este artigo tem por objetivo avaliar o papel do fator de visão do céu na intensidade de ilhas de calor em um bairro residencial. Primeiro, foram feitas caracterizações da área de estudo e determinação da geometria urbana, utilizando-se como unidade geométrica o fator de visão do céu. Foram selecionados pontos de referência e realizadas medições de temperatura do ar em cânions urbanos. A partir de dados disponibilizados pela estação meteorológica localizada em área rural, foram feitas comparações entre os pontos e a área rural, gerando dados de intensidade das ilhas de calor. Através da identificação das tendências térmicas da área, os dados de máxima intensidade da ilha noturna em cada ponto serviram de base para a comparação com um modelo empírico. Propôs-se uma equação de correção, e dados reais de pesquisas anteriores foram comparados com dados simulados pela nova equação. Os resultados indicam que a temperatura urbana noturna varia de acordo com a faixa de fator de visão do céu considerada.
Computerized Dynamic Testing: A Study of the Potential of an Approach Using Sensor Technology
Authors: Resing Wilma C. M. , Steijn Wouter M. P. , Xenidou-Dervou Iro , Stevenson Claire E. , Elliott Julian G.
Published: September 2011

This study explored the use of computerized dynamic testing in education for 8-year-old children. As for other domains, it was expected that the use of a computer would help overcome difficulties encountered with traditional dynamic test procedures. A recently developed computerized console was used, based on sensor technology, in combination with electronic tangibles. The main aim was to investigate if dynamic testing with graduated prompts offered by a computerized interface provided richer and more extensive information about test performance than with prompts offered by an examiner. Fifty-four children participated in the dynamic test procedure, which used a pretest–posttest training design. The results indicated no significant differences in children’s performance based on whether prompts were offered by either the computer or by an examiner. The suitability of the procedure was measured by several behavioral outcome scores, the recording of which was made possible by the use of sensor technology. In the light of the findings, the authors conclude that dynamic testing can profit greatly from the use of computerized procedures.
Evaluating performance of vertical flow constructed wetland under various hydraulic loading rates in effluent polishing
Authors: Maina C. W. , Mutua B. M. , Oduor S. O.
Published: September 2011

The discharge of untreated wastewater or partially treated effluent and runoff from agricultural fields into water bodies is a major source of surface water pollution worldwide. To mitigate this problem, wastewater treatment using wastewater stabilization ponds and constructed wetlands have been promoted. The performance of such wastewater treatment systems is strongly dependent on their hydraulics, which if not properly considered during design or operation, may result in the partially treated effluent being discharged into water bodies. This paper presents results from a study that was carried out to evaluate the performance of a vertical flow constructed wetland system under varying hydraulic loading regimes. The influent and effluent samples from the constructed wetland were collected and analysed for physical, chemical and biological parameters of importance to water quality based on recommended standard laboratory methods. The data collected was useful in determining the treatment efficiency of the wetland. The hydraulic loading rate applied ranged between 0.014 and 0.174 m/day. Phosphorus reduction for the different hydraulic loading rates ranged between 92 and 47% for lowest and highest loading rates applied respectively. However, ammonium nitrogen reduction was not significantly affected by the different hydraulic loading rates, since the reduction ranged between 97 and 94%.
Accounting Choice and the Fair Value Option
Authors: Guthrie Katherine , Irving James H. , Sokolowsky Jan
Published: September 2011

SYNOPSIS

Under the fair value option, SFAS No. 159, firms have full discretion over electing to report specified financial instruments at fair value on a contract-by-contract basis. Building on Henry's (2009) study of early adopting banks, this paper examines to what extent firms' election of instruments benefited their current or future earnings. Our sample comprises the constituents of the S&P 1500 Index for the first quarters of fiscal years 2007 and 2008. Expanding the sample across industries and over time allows us to obtain a more complete picture of the adoption of the fair value option. We identify 72 adopters, two-thirds of which are not commercial banks. We do not find evidence of systematic opportunistic election of the fair value option. In only a handful of cases—concentrated among early adopters with an earnings shortfall—did firms experience a significant improvement in current or future earnings that casts doubt on whether their adoption was keeping with the intent and spirit of the standard.

Data Availability: The list of adopters used in this paper is available from the authors upon request.
Was the Sarbanes-Oxley Act Good News for Corporate Bondholders?
Authors: DeFond Mark L. , Hung Mingyi , Carr Emre , Zhang Jieying
Published: September 2011

SYNOPSIS

We investigate the impact of the Sarbanes-Oxley Act (SOX) on corporate bondholder value by examining the bond market reaction to news events leading up to the passage of SOX. The net impact of SOX on bondholder value is difficult to predict, and there are many reasons why it may be viewed as either good or bad news. Our primary analysis reveals a significant decline in average bondholder value around these events. In addition, cross-sectional tests find that the decline is significantly larger among riskier bonds and among bonds held by firms that are expected to experience the greatest changes under SOX. Thus, our findings are consistent with the bond market expecting the exogenously imposed changes under SOX to make bondholders worse off.
Logics for stable and unstable mereological relations
Authors: Nenchev Vladislav
Published: September 2011

In this paper we present logics about stable and unstable versions of several well-known relations from mereology: part-of, overlap and underlap. An intuitive semantics is given for the stable and unstable relations, describing them as dynamic counterparts of the base mereological relations. Stable relations are described as ones that always hold, while unstable relations hold sometimes. A set of first-order sentences is provided to serve as axioms for the stable and unstable relations, and representation theory is developed in similar fashion to Stone’s representation theory for distributive lattices.

First-order predicate logic and modal logic are presented with semantics based on structures with stable and unstable mereological relations. Completeness theorems for these logics are proved, as well as decidability in the case of the modal logic, hereditary undecidability in the case of the first-order logic, and NP-completeness for the satisfiability problem of the quantifier-free fragment of the first-order logic.
The annual glaciohydrology cycle in the ablation zone of the Greenland ice sheet: Part 1. Hydrology model
Authors: Colgan William , Rajaram Harihar , Anderson Robert , Steffen Konrad , Phillips Thomas , Joughin Ian , Jay Zwally H. , Abdalati Waleed
Published: September 2011

We apply a novel one-dimensional glacier hydrology model that calculates hydraulic head to the tidewater-terminating Sermeq Avannarleq flowline of the Greenland ice sheet. Within a plausible parameter space, the model achieves a quasi-steady-state annual cycle in which hydraulic head oscillates close to flotation throughout the ablation zone. Flotation is briefly achieved during the summer melt season along a ∼17 km stretch of the ∼50 km of flowline within the ablation zone. Beneath the majority of the flowline, subglacial conduit storage ‘closes’ (i.e. obtains minimum radius) during the winter and ‘opens’ (i.e. obtains maximum radius) during the summer. Along certain stretches of the flowline, the model predicts that subglacial conduit storage remains open throughout the year. A calculated mean glacier water residence time of ∼2.2 years implies that significant amounts of water are stored in the glacier throughout the year. We interpret this residence time as being indicative of the timescale over which the glacier hydrologic system is capable of adjusting to external surface meltwater forcings. Based on in situ ice velocity observations, we suggest that the summer speed-up event generally corresponds to conditions of increasing hydraulic head during inefficient subglacial drainage. Conversely, the slowdown during fall generally corresponds to conditions of decreasing hydraulic head during efficient subglacial drainage.
In situ quantification of supraglacial cryoconite morphodynamics using time-lapse imaging: an example from Svalbard
Authors: Irvine-Fynn Tristram D.L. , Bridge Jonathan W. , Hodson Andrew J.
Published: September 2011

There is growing recognition of the significance of biologically active supraglacial dust (cryoconite) for glacial mass balance and ecology. Nonetheless, the processes controlling the distribution, transport and fate of cryoconite particles in the glacial system remain somewhat poorly understood. Here, using a 216 hour time series of plot-scale (0.04 m2) images, we quantify the small-scale dynamics of cryoconite on Longyearbreen, Svalbard. We show significant fluctuations in the apparent cryoconite area and dispersion of cryoconite over the plot, within the 9 day period of observations. However, the net movement of cryoconite across the ice surface averaged only 5.3 mm d−1. High-resolution measurements of cryoconite granule motion showed constant, random motion but weak correlation with meteorological forcing factors and no directional trends for individual particle movement. The high-resolution time-series data suggest that there is no significant net transport of dispersed cryoconite material across glacier surfaces. The areal coverage and motion of particles within and between cryoconite holes appears to be a product of differential melting leading to changes in plot-scale microtopography, local meltwater flow dynamics and weather-dependent events. These subtle processes of cryoconite redistribution may be significant for supraglacial albedo and have bearing on the surface energy balance at the glacier scale.
Assessment of multispectral glacier mapping methods and derivation of glacier area changes, 1978–2002, in the central Southern Alps, New Zealand, from ASTER satellite data, field survey and existing inventory data
Authors: Gjermundsen E.F. , Mathieu R. , Kääb A. , Chinn T. , Fitzharris B. , Hagen J.O.
Published: September 2011

We have measured the glacier area changes in the central Southern Alps, New Zealand, between 1978 and 2002 and have compiled the 2002 glacier outlines using an image scene from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER). Three automated classification methods were tested: (1) band ratio, (2) normalized-difference snow index and (3) supervised classification. The results were compared with the glacier outlines photo-interpreted from the ASTER data, and were further validated using GPS-aided field mapping of selected test glaciers. The ASTER 3/4 band ratio provided the best results. However, all the classification methods failed to extract extensive debris-covered parts of the glaciers. Therefore, the photo-interpreted 2002 outlines were used when comparing with the existing 1978 glacier inventory derived from aerial photographs. Our results show a ∼17% reduction of glacier area, mainly driven by the retreat of the large valley glaciers. Despite the large climatic gradient from west to east, glaciers on both sides of the Main Divide lost similar percentages of area, except Franz Josef and Fox Glaciers which advanced. Smaller glaciers were found to have changed very little in the study period.
2001–2009 elevation and mass losses in the Larsen A and B embayments, Antarctic Peninsula
Authors: Shuman Christopher A. , Berthier Etienne , Scambos Ted A.
Published: September 2011

We investigate the elevation and mass-balance response of tributary glaciers following the loss of the Larsen A and B ice shelves, Antarctic Peninsula (in 1995 and 2002 respectively). Our study uses MODIS imagery to track ice extent, and ASTER and SPOT5 digital elevation models (DEMs) plus ATM and ICESat laser altimetry to track elevation changes, spanning the period 2001–09. The measured Larsen B tributary glaciers (Hektoria, Green, Evans, Punchbowl, Jorum and Crane) lost up to 160 m in elevation during 2001–06, and thinning continued into 2009. Elevation changes were small for the more southerly Flask and Leppard Glaciers, which are still constrained by a Larsen B ice shelf remnant. In the northern embayment, continued thinning of >3 m a−1 on Drygalski Glacier, 14 years after the Larsen A ice shelf disintegrated, suggests that mass losses for the exposed Larsen B tributaries will continue for years into the future. Grounded ice volume losses exceed 13 km3 for Crane Glacier and 30 km3 for the Hektoria–Green–Evans glaciers. The combined mean loss rate for 2001–06 is at least 11.2 Gt a−1. Our values differ significantly from published mass-budget-based estimates for these embayments, but are a reasonable fraction of GRACE-derived rates for the region (∼40 Gt a−1).
Blind Deconvolution of Seismic Data Using f-Divergences
Authors: Zhang Bing , Gao Jing-Huai
Published: September 2011

This paper proposes a new approach to the seismic blind deconvolution problem in the case of band-limited seismic data characterized by low dominant frequency and short data records, based on Csiszár’s f-divergence. In order to model the probability density function of the deconvolved data, and obtain the closed form formula of Csiszár’s f-divergence, mixture Jones’ family of distributions (MJ) is introduced, by which a new criterion for blind deconvolution is constructed. By applying Neidell’s wavelet model to the inverse filter, we then make the optimization program for multivariate reduce to univariate case. Examples are provided showing the good performance of the method, even in low SNR situations.
Effects of St John's Wort (Hypericum perforatum L.) Extracts on Epileptogenesis
Authors: Ivetic Vesna , Trivic Svetlana , Pogancev Marija Knezevic , Popovic Mira , Zlinská Janka
Published: September 2011

The purpose of this study was to investigate the effects of treatment with water, n-butanol and ether extracts of Hypercom perforatum L. on epileptogenesis in rabbits. Animals from the control group received solvent-ethanol, and the kindling model of epilepsy was used. Epileptic focus was induced in Chinchilla rabbits by stimulation of the hippocampus. The following parameters were determined: the minimum current strength necessary to induce after-discharge (AD) – discharges appearing after cessation of stimulation; AD duration; the number of stimulations necessary to induce spontaneous kindling; and the latency time for the development of full kindling. The results obtained indicate that epileptogenesis is influenced by Hypericum perforatum L. extract treatment. Animals treated with an ether extract of Hypericum perforatum L. required significantly weaker minimum current strengths for the development of epileptogenic focus, and displayed longer AD times, while the number of electro-stimulations necessary for full kindling was less. In contrast, animals treated with water and n-butanol extracts required increased electro-stimulations for the development of epileptic discharge, and displayed shortened AD durations versus controls.
La peur de la pénalité chez le joueur de rugby : histoire et diffusion du sport
Authors: Collins Tony
Published: September 2011

L'importance de la pénalité (penalty) dans le rugby à XV trouve son origine dans les classes moyennes anglaises qui conçurent ce sport à l'époque victorienne. Or, ses dirigeants anglais ne souhaitaient pas en général que le rugby se « diffuse » et la crainte de la pénalité, à la fois sur le terrain et en dehors, est devenue l'un de ses traits distinctifs. Cet article montre que le processus d'expansion d'un sport ne se réduit pas à une « diffusion » naturelle ou spontanée. Les décisions prises par ses premiers dirigeants concernant son développement jouent également un rôle essentiel.
What's in a Name? Playing “Football” in the Mid-Victorian North-Eastern England
Authors: Kitching Gavin
Published: September 2011

Jouer au « football » dans le nord-est de l’Angleterre victorienne La transition des formes traditionnelles de jeux populaires en sports modernes a souvent été simplement perçue comme une manifestation de la modernisation de la société. D'un point de vue général, cette explication n'est pas fausse, mais il y a quelques points qu'elle n'explique pas, plus particulièrement pourquoi certains jeux « transformés en sport » sont devenus plus populaires que d'autres dans les sociétés modernisées. Pour étudier cette question de différence de popularité, cet article s'intéresse à la transition depuis les formes traditionnelles du « football » jusqu'au soccer et au rugby modernes dans le nord-est de l'Angleterre victorienne.
Nation et narration dans la diffusion sportive : l'exemple des courses de chevaux dans l'Algérie coloniale
Authors: Dine Philip
Published: September 2011

Les courses hippiques constituent la première pratique sportive moderne de l'Algérie coloniale (1830-1962). Des officiers français de cavalerie y ont encouragé la participation d'élites indigènes afin d'inculquer des valeurs censées être favorables au projet colonial. Ce texte propose une analyse du discours de deux réunions hippiques de septembre 1852 en vue d'établir les paramètres institutionnels et idéologiques du processus de la diffusion sportive sur le territoire colonisé.
Les navigatrices de course au large. Une socialisation professionnelle spécifique
Authors: Le Bars Cécile , Lacombe Philippe
Published: September 2011

Nous nous proposons ici d'analyser et de comparer les processus et les mécanismes à l'œuvre au cours de l'insertion professionnelle des navigateurs[trices] dans le monde de la course au large. Si cette séquence de la carrière ne présente pas un caractère linéaire et continu, pour les hommes comme pour les femmes, elle révèle en revanche des perspectives différenciées en termes de genre. Les navigatrices, en effet, rendent compte d'une exclusion quasi systématique des rôles de préparatrices techniques et/ou d'équipières lors de la phase de primo-insertion. Elles n'ont alors d'autre choix que celui de débuter leur carrière comme skippers de course au large en solitaire.
Le théâtre des fumeurs de « crack ». Mise en scène émotionnelle et voilement/dévoilement de soi
Authors: Fernandez Fabrice
Published: September 2011

À partir d'une enquête ethnographique dans le quartier de la Goutte-d'Or à Paris, cet article interroge le jeu des émotions durant les scènes collectives de consommation de crack. Derrière les apparences du discours irrationnel, la mise en scène des émotions et le voilement/dévoilement de soi participent à construire du sens à ces interactions « sous influence » à l'intérieur des squats précaires, réarticulant des expériences hétérogènes dans la continuité de parcours de vie.
Evaluation et mesure des politiques de diversité culturelle
Authors: Guerfel-Henda Sana , Broussillon George-Axelle
Published: September 2011

Résumé La gestion des diversités notamment culturelles est devenue une nécessité pour les organisations, en raison des récentes évolutions sociétales (création de la Charte de la Diversité, de la HALDE, du Label diversité) et des avantages en termes de performance économique et d’innovation. Toutefois, la question de l’évaluation de ces politiques appliquée à la diversité culturelle reste complexe puisque qu’elle pose celle de la mesure de la diversité des « spécificités culturelles » ou ethno-raciales et celle de l’évaluation des discriminations raciales. Pour dépasser l’absence de catégorisations ethnoraciales et respecter le cadre législatif imposé par la CNIL, les entreprises évaluent leurs processus RH et leurs moyens d’action avec des instruments comme l’audit social, le Label diversité ou le testing. Ces évaluations qualitatives s’accompagnent parfois de démarches quantitatives, telles que les analyses de recrutements ou d’effectifs qui s’appuient sur le patronyme ou lieu de résidence. Bien qu’efficaces, ces outils restent controversés et ne sauraient être des fins en soi, puisqu’il s’agit d’évaluer plus largement le processus de changement de culture de l’entreprise en tant que telle.
Le CV anonyme : les visions des DRH
Authors: Ben Yedder Moez , Frimousse Soufyane , Peretti Jean-Marie
Published: September 2011

Résumé Le management de la diversité constitue un défi central des politiques et des pratiques de ressources humaines. En matière de recrutement, les enjeux et les risques sont particulièrement importants. Des comportements discriminatoires à l’embauche peuvent être intentionnels ou se produire par défaut de professionnalisme ou par méconnaissance. L’évaluation de l’impact des mesures visant à inscrire la non-discrimination, l’égalité de traitement et l’égalité des chances dans les politiques, les pratiques et les outils de gestion des ressources humaines est délicate. Parmi ces pratiques, le CV anonyme fait, ces dernières années, l’objet de vifs débats. Cet article présente l’évaluation et les perceptions de cet outil par les DRH, en première ligne face aux enjeux de la diversité.
Ontologie de la décision individuelle et neurosciences : enjeux méthodologiques et épistémologiques
Authors: Marchais-Roubelat Anne
Published: September 2011

Résumé Les théories de la décision sont fondées sur le concept d’individu, unité décisionnelle abstraite, isolée et indivisible qui ne risque pas d’être trompée par ses sens. Les neurosciences n’interrogent pas la notion d’individu, et pourtant elles en contiennent la critique : leurs méthodes d’investigation font apparaître un être vivant, parcouru de processus décisionnels entrelacés qui non seulement ignorent la frontière entre l’individu et son environnement mais encore interagissent selon des temporalités multiples. Les recherches en management peuvent-elles s’approprier la conception vivante du décideur dont sont porteuses les neurosciences pour susciter l’émergence d’un paradigme décisionnel plus adapté à l’action ?
Choix méthodologiques en Sciences de Gestion : pourquoi tant de chiffres ?
Authors: Maurand-Valet Anne
Published: September 2011

Résumé Nous nous sommes interrogés sur l’augmentation du degré de formalisation des méthodes de recherche en sciences de gestion. Les explications que nous avançons sont de deux types : des facteurs psychologiques (confiance suscitée par des résultats chiffrés et recherche de la généralisation), des facteurs sociologiques (crédibilité scientifique, facilité de communication des résultats et reconnaissance par les pairs).
De la cohérence du style de rédaction avec le positionnement épistémologique du chercheur
Authors: Diné Sébastien
Published: September 2011

Résumé Le style de rédaction n’est pas neutre, il traduit le positionnement épistémologique du chercheur. C’est en partant de ce postulat que je me suis interrogé sur la manière dont le style de rédaction du chercheur reflète implicitement une hypothèse sur la nature de la « réalité ». Cette question intéresse tout chercheur souhaitant mettre en adéquation l’articulation ontologie/épistémologie/méthodologie de sa recherche. Les travaux des linguistes et philosophes nous révèlent que certaines structures actuelles de notre langage postulent implicitement une « réalité » indépendante de son auteur. Dès lors, je proposerai dans cet article un style de rédaction tentant de rendre compte de la dépendance du chercheur à la « réalité » retranscrite, et contribuer ainsi aux conditions de réflexion d’un « foisonnement épistémologique ».
Comment étudier le matériau de gestion ? Propositions méthodologiques
Authors: Jardat Rémi
Published: September 2011

Résumé La complexité des terrains qu’elles étudient amène les sciences de gestion à recourir à de nombreux emprunts transdisciplinaires. Il en résulte une ambiguïté quant à la pertinence et à la légitimité des productions académiques de gestion, face à laquelle un changement de période en matière d’écrits épistémologiques, mais aussi méthodologiques, s’avère nécessaire. Il est tout d’abord proposé ici de reformuler axiomatiquement l’objet comme l’objectif des sciences de gestion, sous l’angle de la représentation. Cet angle d’attaque, qui permet l’application de considérations structuralistes au sens large, amène à formuler plusieurs propositions d’ordre méthodologique visant à opérationnaliser en gestion les approches herméneutiques. Cinq jalons-clés de la démarche de recherche en gestion sont mis en avant, qui s’appuient pour partie sur le structuralisme des géologues : « élargir progressivement les cercles herméneutiques », « dé-plier les représentations de proche en proche », « repérer le front de schistosité », « redistribuer les représentations en un méga-pli unique » et enfin « repousser le front de schistosité ». Destinée à permettre au chercheur de croiser les disciplines tout en mesurant en quoi diffèrent ressemblances profondes d’une part et ressemblances superficielles d’autre part, une telle approche se veut tout aussi bien modulatrice que génératrice et régulatrice du travail scientifique.