Showing papers by "Bar-Ilan University published in 2009"

On the Surface Chemical Aspects of Very High Energy Density, Rechargeable Li–Sulfur Batteries

Abstract: Li(metal)-sulfur (Li-S) systems are among the rechargeable batteries of the highest possible energy density due to the high capacity of both electrodes. The surface chemistry developed on Li electrodes in electrolyte solutions for Li-S batteries was rigorously studied using Fourier transform infrared and X-ray photoelectron spectroscopies. A special methodology was developed for handling the highly reactive Li samples. It was possible to analyze the contribution of solvents such as 1-3 dioxolane, the electrolyte LiN(SO 2 CF 3 ) 2 , polysulfide (Li 2 S n ), and LiNO 3 additives to protective surface films that are formed on the Li electrodes. The role of LiNO 3 as a critical component whose presence in solutions prevents a shuttle mechanism that limits the capacity of the sulfur electrodes is discussed and explained herein.

A cross-national profile of bullying and victimization among adolescents in 40 countries

Abstract: Objectives: (1) To compare the prevalence of bullying and victimization among boys and girls and by age in 40 countries. (2) In 6 countries, to compare rates of direct physical, direct verbal, and indirect bullying by gender, age, and country.

Enhanced Antibacterial Activity of Nanocrystalline ZnO Due to Increased ROS-Mediated Cell Injury

Abstract: An innovative study aimed at understanding the influence of the particle size of ZnO (from the microscale down to the nanoscale) on its antibacterial effect is reported herein. The antibacterial activity of ZnO has been found to be due to a reaction of the ZnO surface with water. Electron-spin resonance measurements reveal that aqueous suspensions of small nanoparticles of ZnO produce increased levels of reactive oxygen species, namely hydroxyl radicals. Interestingly, a remarkable enhancement of the oxidative stress, beyond the level yielded by the ZnO itself, is detected following the antibacterial treatment. Likewise, an exposure of bacteria to the small ZnO nanoparticles results in an increased cellular internalization of the nanoparticles and bacterial cell damage. An examination of the antibacterial effect is performed on two bacterial species: Escherichia coli (Gram negative) and Staphylococcus aureus (Gram positive). The nanocrystalline particles of ZnO are synthesized using ultrasonic irradiation, and the particle sizes are controlled using different solvents during the sonication process. Taken as a whole, it is apparent that the unique properties (i.e., small size and corresponding large specific surface area) of small nanometer-scale ZnO particles impose several effects that govern its antibacterial action. These effects are size dependent and do not exist in the range of microscale particles.

A Proof of Security of Yao’s Protocol for Two-Party Computation

Abstract: In the mid 1980s, Yao presented a constant-round protocol for securely computing any two-party functionality in the presence of semi-honest adversaries (FOCS 1986). In this paper, we provide a complete description of Yao’s protocol, along with a rigorous proof of security. Despite the importance of Yao’s protocol to the theory of cryptography and in particular to the field of secure computation, to the best of our knowledge, this is the first time that an explicit proof of security has been published.

Secure Multiparty Computation for Privacy-Preserving Data Mining

Abstract: In this paper, we survey the basic paradigms and notions of secure mul- tiparty computation and discuss their relevance to the fleld of privacy-preserving data mining. In addition to reviewing deflnitions and constructions for secure mul- tiparty computation, we discuss the issue of e-ciency and demonstrate the di-cul- ties involved in constructing highly e-cient protocols. We also present common errors that are prevalent in the literature when secure multiparty computation techniques are applied to privacy-preserving data mining. Finally, we discuss the relationship between secure multiparty computation and privacy-preserving data mining, and show which problems it solves and which problems it does not.

High‐quality relationships, psychological safety, and learning from failures in work organizations

Abstract: How can organizations support employees to engage in learning from failures? In this paper, we draw on the concept of high-quality relationships to explore the relational underpinnings of learning from failures in organizations. We focus on relational coordination as a specific manifestation of high-quality relationships and examine how the relational dimensions of relational coordination—shared goals, shared knowledge, and mutual respect—foster psychological safety and thus enable organizational members to engage in learning from failures. The results of two separate studies support our mediation model where psychological safety mediates the link between high-quality relationships and learning from failures in organizations. Copyright © 2008 John Wiley & Sons, Ltd.

Computational methods in authorship attribution

Abstract: Statistical authorship attribution has a long history, culminating in the use of modern machine learning classification methods. Nevertheless, most of this work suffers from the limitation of assuming a small closed set of candidate authors and essentially unlimited training text for each. Real-life authorship attribution problems, however, typically fall short of this ideal. Thus, following detailed discussion of previous work, three scenarios are considered here for which solutions to the basic attribution problem are inadequate. In the first variant, the profiling problem, there is no candidate set at all; in this case, the challenge is to provide as much demographic or psychological information as possible about the author. In the second variant, the needle-in-a-haystack problem, there are many thousands of candidates for each of whom we might have a very limited writing sample. In the third variant, the verification problem, there is no closed candidate set but there is one suspect; in this case, the challenge is to determine if the suspect is or is not the author. For each variant, it is shown how machine learning methods can be adapted to handle the special challenges of that variant. © 2009 Wiley Periodicals, Inc.

Neuropsychological Function and Dysfunction in Schizophrenia and Psychotic Affective Disorders

Abstract: Background: Mounting evidence suggests that compromised neurocognitive function is a central feature of schizophrenia. There are, however, schizophrenia patients with a normal neuropsychological (NP) performance, but estimates of the proportion of NP normal patients vary considerably between studies. Neurocognitive dysfunction is also a characteristic of other psychotic disorders, yet there are inconsistencies in the literature regarding the similarity to impairments in schizophrenia. NP normality in psychotic affective disorders has not been systematically studied. Methods: Data came from the Suffolk County Mental Health Project, an epidemiological study of first-admission patients with psychotic disorders. Respondents with a diagnosis of schizophrenia (N = 94) or schizoaffective disorder (N = 15), bipolar disorder (N = 78), and major depressive disorder (N = 48) were administered a battery of NP tests assessing 8 cognitive domains 2 years after index admission. Patients’ performance profile was compared, and their NP status was classified based on 3 previously published criteria that vary in their stringency. Results: The 4 diagnostic groups had comparable NP performance profile patterns. All groups demonstrated impairments in memory, executive functions, and attention and processing speed. However, schizophrenia patients were more impaired than the other groups on all cognitive domains. Results were not attenuated when IQ was controlled. Prevalence of NP normality ranged between 16% and 45% in schizophrenia, 20% and 33% in schizoaffective disorder, 42% and 64% in bipolar disorder, and 42% and 77% in depression, depending on the criterion employed. Conclusions: Evidence suggests that differences in NP performance between schizophrenia and psychotic affective disorders are largely quantitative. NP impairment is also common in psychotic affective disorders. A significant minority of schizophrenia patients are NP normal.

p53 and E2f: partners in life and death

Abstract: During tumour development cells sustain mutations that disrupt normal mechanisms controlling proliferation. Remarkably, the Rb-E2f and MDM2-p53 pathways are both defective in most, if not all, human tumours, which underscores the crucial role of these pathways in regulating cell cycle progression and viability. A simple interpretation of the observation that both pathways are deregulated is that they function independently in the control of cell fate. However, a large body of evidence indicates that, in addition to their independent effects on cell fate, there is extensive crosstalk between these two pathways, and specifically between the transcription factors E2F1 and p53, which influences vital cellular decisions. This Review discusses the molecular mechanisms that underlie the intricate interactions between E2f and p53.

Transient anomalous diffusion of telomeres in the nucleus of mammalian cells.

Abstract: We measured individual trajectories of fluorescently labeled telomeres in the nucleus of eukaryotic cells in the time range of 10-2–104 sec by combining a few acquisition methods. At short times the motion is subdiffusive with (r2)?t? and it changes to normal diffusion at longer times. The short times diffusion may be explained by the reptation model and the transient diffusion is consistent with a model of telomeres that are subject to a local binding mechanism with a wide but finite distribution of waiting times. These findings have important biological implications with respect to the genome organization in the nucleus.

Alive and creating: The mediating role of vitality and aliveness in the relationship between psychological safety and creative work involvement.

Abstract: Individual involvement in creative work is of crucial importance for organizations in a knowledge-based economy. This study examined how psychological safety induces feelings of vitality and how feelings of vitality impact one's involvement in creative work. We examined these relationships among 128 part-time graduate students who held managerial and non-managerial position in their work organizations. The results suggest that employees' sense of psychological safety is significantly associated with feelings of vitality (both collected at time 1), which, in turn, result in involvement in creative work (collected at time 2). We discuss the implications of these findings for both theory and practice. Copyright © 2008 John Wiley & Sons, Ltd.

Learning behaviours in the workplace: The role of high-quality interpersonal relationships and psychological safety

Abstract: Organizational learning is an important means for improving performance. Learning is a process, that is, often relational in the sense of relying on interactions between people to determine what needs improving and how to do it. This study addresses the question of how the quality of work relationships facilitates learning behaviours in organizations through the ways it contributes to psychological safety. Data collected from 212 part-time students who hold full-time jobs in organizations operating in a wide variety of industries show that capacities of high-quality relationships (measured at time 1) are positively associated with psychological safety, which, in turn, are related to higher levels of learning behaviours (measured at time 2). The results also show that experiences of high-quality relationships (measured at time 1) are both directly and indirectly (through psychological safety) associated with learning behaviours (measured at time 2). These findings shed light on the importance of quality relationships in the workplace for cultivating and developing perceptions of psychological safety and ultimately learning behaviours in organizations. Copyright © 2008 John Wiley & Sons, Ltd.

Leader–member exchange, feelings of energy, and involvement in creative work

Abstract: This study examined how leaders create the impetus for creativity at work. One hundred ninety-three employees occupying a variety of jobs in Israeli organizations completed surveys at two points in time to assess their perceptions of the quality of their relationship with their leader (LMX), their level of energy, and their creative work involvement. SEM and regression analyses showed that LMX was positively related to employees' feelings of energy, which in turn were related to a high level of involvement in creative work. Factors that leaders should take into consideration in promoting followers' creative behaviors are discussed.

Socioeconomic Inequality in Exposure to Bullying During Adolescence: A Comparative, Cross-Sectional, Multilevel Study in 35 Countries

Abstract: Objectives. We examined the socioeconomic distribution of adolescent exposure to bullying internationally and documented the contribution of the macroeconomic environment.Methods. We used an international survey of 162 305 students aged 11, 13, and 15 years from nationally representative samples of 5998 schools in 35 countries in Europe and North America for the 2001–2002 school year. The survey used standardized measures of exposure to bullying and socioeconomic affluence.Results. Adolescents from families of low affluence reported higher prevalence of being victims of bullying (odds ratio [OR] = 1.13; 95% confidence interval [CI] = 1.10, 1.16). International differences in prevalence of exposure to bullying were not associated with the economic level of the country (as measured by gross national income) or the school, but wide disparities in affluence at a school and large economic inequality (as measured by the Gini coefficient) at the national level were associated with an increased prevalence of expo...

Trust, Connectivity, and Thriving: Implications for Innovative Behaviors at Work

Abstract: This study examines how trust, connectivity and thriving drive employees’ innovative behaviors in the workplace. Using a sample of one hundred and seventy two employees across a variety of jobs and industries, we investigated the relationship between trust, connectivity (both measured at Time 1), thriving and innovative work behaviors (both measured at Time 2). Trust and connectivity were hypothesized to create a nurturing environment that enables people to thrive and be innovative in their work. The results of structural equation modeling (SEM) indicate a sequential mediation model in which connectivity mediates the relationship between trust and thriving, and thriving mediates the relationship between connectivity and innovative behaviors. The theoretical and practical implications for employee thriving and innovative behaviors at work are discussed.

Ultrahigh-speed random number generation based on a chaotic semiconductor laser.

Abstract: The fluctuating intensity of a chaotic semiconductor laser is used for generating random sequences at rates up to 12.5 Gbits/s. The conversion of the fluctuating intensity to a random bit sequence can be implemented in either software or hardware and the overall rate of generation is much faster than any previously reported random number generator based on a physical mechanism. The generator's simplicity, robustness, and insensitivity to control parameters should enable its application to tasks of secure communication and calculation procedures requiring ultrahigh-speed generation of random bit sequences.

Human Merkel cell polyomavirus infection I. MCV T antigen expression in Merkel cell carcinoma, lymphoid tissues and lymphoid tumors.

Abstract: Merkel cell polyomavirus (MCV) is a recently discovered human virus closely related to African green monkey lymphotropic polyomavirus. MCV DNA is integrated in approximately 80% of Merkel cell carcinomas (MCC), a neuroendocrine skin cancer linked to lymphoid malignancies such as chronic lymphocytic leukemia (CLL). To assess MCV infection and its association with human diseases, we developed a monoclonal antibody that specifically recognizes endogenous and transfected MCV large T (LT) antigen. We show expression of MCV LT protein localized to nuclei of tumor cells from MCC having PCR quantified MCV genome at an average of 5.2 (range 0.8-14.3) T antigen DNA copies per cell. Expression of this putative viral oncoprotein in tumor cells provides the mechanistic underpinning supporting the notion that MCV causes a subset of MCC. In contrast, although 2.2% of 325 hematolymphoid malignancies surveyed also showed evidence for MCV infection by DNA PCR, none were positive at high viral copy numbers, and none of 173 lymphoid malignancies examined on tissue microarrays expressed MCV LT protein in tumor cells. As with some of the other human polyomaviruses, lymphocytes may serve as a tissue reservoir for MCV infection, but hematolymphoid malignancies associated with MCC are unlikely to be caused by MCV.

Investigation, treatment and monitoring of late-onset hypogonadism in males

Abstract: *Corresponding Author Androgen deficiency in the aging male has become a topic of increasing interest and debate throughout the world. The demographics clearly demonstrate the increasing percentage of the population that is in the older age groups. The data also support the concept that testosterone falls progressively with age and that a significant percentage of men over the age of 60 years have serum testosterone levels that are below the lower limits of young adults (age 20-30 years) men. The principal questions raised by these observations are whether older hypogonadal men will benefit from testosterone treatment and what will be the risks associated with such intervention. The past decade has brought evidence of benefit of androgen treatment on multiple target organs of hypogonadal men and recent studies show short-term beneficial effects of testosterone in older men that are similar to those in younger men. Long-term data on the effects of testosterone treatment in the older population are limited and specific risk data on the prostate and cardiovascular systems are needed. Answers to key questions of functional benefits that may retard frailty of the elderly are not yet available. The recommendations described below were prepared for the International Society of Andrology (ISA) and the International Society for the Study of the Aging Male (ISSAM) following a panel discussion with active participation from the audience sponsored by the ISA on the topic at the 4th ISSAM Congress in Prague in February 2004. The ISA Member Societies were requested to comment on the draft recommedations. Representatives of the European Association of Urology (EAU) participated in the final draft of this document. This document is not intended to provide evidence for each recommendation as review of pertinent studies have recently been comprehensively summarized in the Clinical Research Directions on “Testosterone and Aging” by the Institute of Medicine (Washington 2004). The recommendations will be subject to revision as larger-scale and longer-term data become available. In order to reach a large audience these recommendations are published in the International Journal of Andrology,the Journal of Andrology, The Aging Male and in European Urology. E Nieschlag * Institute of Reproductive Medicine University of Münster, Germany Email: eberhard.nieschlag@ukmuenster.de

Ergodic properties of fractional Brownian-Langevin motion

Abstract: We investigate the time average mean-square displacement $\overline{{\ensuremath{\delta}}^{2}}\mathbf{(}x(t)\mathbf{)}={\ensuremath{\int}}_{0}^{t\ensuremath{-}\ensuremath{\Delta}}{[x({t}^{\ensuremath{'}}+\ensuremath{\Delta})\ensuremath{-}x({t}^{\ensuremath{'}})]}^{2}d{t}^{\ensuremath{'}}∕(t\ensuremath{-}\ensuremath{\Delta})$ for fractional Brownian-Langevin motion where $x(t)$ is the stochastic trajectory and $\ensuremath{\Delta}$ is the lag time. Unlike the previously investigated continuous-time random-walk model, $\overline{{\ensuremath{\delta}}^{2}}$ converges to the ensemble average $⟨{x}^{2}⟩\ensuremath{\sim}{t}^{2H}$ in the long measurement time limit. The convergence to ergodic behavior is slow, however, and surprisingly the Hurst exponent $H=\frac{3}{4}$ marks the critical point of the speed of convergence. When $Hl\frac{3}{4}$, the ergodicity breaking parameter ${E}_{B}={\mathbf{[}⟨[\overline{{\ensuremath{\delta}}^{2}}\mathbf{(}x(t)\mathbf{)}\mathbf{]}}^{2}⟩\ensuremath{-}{⟨\overline{{\ensuremath{\delta}}^{2}}\mathbf{(}x(t)\mathbf{)}⟩}^{2}\mathbf{]}/{⟨\overline{{\ensuremath{\delta}}^{2}}\mathbf{(}x(t)\mathbf{)}⟩}^{2}\ensuremath{\sim}k(H)\ensuremath{\Delta}{t}^{\ensuremath{-}1}$, when $H=\frac{3}{4}$, ${E}_{B}\ensuremath{\sim}(\frac{9}{16})(\mathrm{ln}\phantom{\rule{0.2em}{0ex}}t)\ensuremath{\Delta}{t}^{\ensuremath{-}1}$, and when $\frac{3}{4}lHl1$, ${E}_{B}\ensuremath{\sim}k(H){\ensuremath{\Delta}}^{4\ensuremath{-}4H}{t}^{4H\ensuremath{-}4}$. In the ballistic limit $H\ensuremath{\rightarrow}1$ ergodicity is broken and ${E}_{B}\ensuremath{\sim}2$. The critical point $H=\frac{3}{4}$ is marked by the divergence of the coefficient $k(H)$. Fractional Brownian motion as a model for recent experiments of subdiffusion of mRNA in the cell is briefly discussed, and a comparison with the continuous-time random-walk model is made.

The induction of autophagy by γ-radiation contributes to the radioresistance of glioma stem cells

Abstract: Malignant gliomas are characterized by a short median survival which is largely impacted by the resistance of these tumors tochemo- and radiotherapy. Recent studies suggest that a small subpopulation of cancer stem cells, which are highly resistant to gamma-radiation, has the capacity to repopulate the tumors and contribute to their malignant progression. gamma-radiation activates the process of autophagy and inhibition of this process increases the radiosensitivity of glioma cells; however, the role of autophagy in the resistance of glioma stem cells (GSCs) to radiation has not been yet reported. In this study we examined the induction of autophagy by gamma-radiation in CD133+ GSCs. Irradiation of CD133+ cells induced autophagy within 24-48 hr and slightly decreased the viability of the cells. gamma-radiation induced a larger degree of autophagy in the CD133+ cells as compared with CD133- cells and the CD133+ cells expressed higher levels of the autophagy-related proteins LC3, ATG5 and ATG12. The autophagy inhibitor bafilomycin A1 and silencing of ATG5 and beclin1 sensitized the CD133+ cells to gamma-radiation and significantly decreased the viability of the irradiated cells and their ability to form neurospheres. Collectively, these results indicate that the induction of autophagy contributes to the radioresistance of these cells and autophagy inhibitors may be employed to increase the sensitivity of CD133+ GSCs to gamma-radiation.

How top management team behavioral integration and behavioral complexity enable organizational ambidexterity: The moderating role of contextual ambidexterity

Abstract: Little is known about how top management teams (TMTs) make balanced strategic decisions (exploration and exploitation) and spearhead organizational ambidexterity. To address the theoretical call to explore how TMTs can help create ambidexterity, we propose a theoretical model where TMT behavioral integration cultivates behavioral complexity in a TMT that can build organizational ambidexterity. Further, we argue that the relationship between TMT behavioral complexity and organizational ambidexterity is moderated by contextual ambidexterity. Drawing on research in the areas of leadership, TMT, organizational context and ambidexterity, we explore implications for future research.

CuO–cotton nanocomposite: Formation, morphology, and antibacterial activity

Abstract: Copper oxide nanoparticles were synthesized and subsequently deposited on the surface of cotton fabrics using ultrasound irradiation. Optimization of the process resulted in a homogeneous distribution of CuO nanocrystals, 15 nm in size, on the fabric surface. The antibacterial activities of the CuO–fabric composite were tested against Escherichia coli (Gram negative) and Staphylococcus aureus (Gram positive) cultures. A significant bactericidal effect, even in a 1% coated fabric (%wt.), was demonstrated.

Multichannel Eigenspace Beamforming in a Reverberant Noisy Environment With Multiple Interfering Speech Signals

Abstract: In many practical environments we wish to extract several desired speech signals, which are contaminated by nonstationary and stationary interfering signals. The desired signals may also be subject to distortion imposed by the acoustic room impulse responses (RIRs). In this paper, a linearly constrained minimum variance (LCMV) beamformer is designed for extracting the desired signals from multimicrophone measurements. The beamformer satisfies two sets of linear constraints. One set is dedicated to maintaining the desired signals, while the other set is chosen to mitigate both the stationary and nonstationary interferences. Unlike classical beamformers, which approximate the RIRs as delay-only filters, we take into account the entire RIR [or its respective acoustic transfer function (ATF)]. The LCMV beamformer is then reformulated in a generalized sidelobe canceler (GSC) structure, consisting of a fixed beamformer (FBF), blocking matrix (BM), and adaptive noise canceler (ANC). It is shown that for spatially white noise field, the beamformer reduces to a FBF, satisfying the constraint sets, without power minimization. It is shown that the application of the adaptive ANC contributes to interference reduction, but only when the constraint sets are not completely satisfied. We show that relative transfer functions (RTFs), which relate the desired speech sources and the microphones, and a basis for the interference subspace suffice for constructing the beamformer. The RTFs are estimated by applying the generalized eigenvalue decomposition (GEVD) procedure to the power spectral density (PSD) matrices of the received signals and the stationary noise. A basis for the interference subspace is estimated by collecting eigenvectors, calculated in segments where nonstationary interfering sources are active and the desired sources are inactive. The rank of the basis is then reduced by the application of the orthogonal triangular decomposition (QRD). This procedure relaxes the common requirement for nonoverlapping activity periods of the interference sources. A comprehensive experimental study in both simulated and real environments demonstrates the performance of the proposed beamformer.

LiMnPO4 as an Advanced Cathode Material for Rechargeable Lithium Batteries

Abstract: LiMnPO4 nanoparticles synthesized by the polyol method were examined as a cathode material for advanced Li-ion batteries. The structure, surface morphology, and performance were characterized by X-ray diffraction, high resolution scanning electron microscopy, high resolution transmission electron microscopy, Raman, Fourier transform IR, and photoelectron spectroscopies, and standard electrochemical techniques. A stable reversible capacity up to 145 mAh g(-1) could be measured at discharge potentials > 4 V vs Li/Li+, with a reasonable capacity retention during prolonged charge/discharge cycling. The rate capability of the LiMnPO4 electrodes studied herein was higher than that of LiNi0.5Mn0.5O2 and LiNi0.8Co0.15Al0.05O2 (NCA) in similar experiments and measurements. The active mass studied herein seems to be the least surface reactive in alkyl carbonate/LiPF6 solutions. We attribute the low surface activity of this material, compared to the lithiated transition-metal oxides that are examined and used as cathode materials for Li-ion batteries, to the relatively low basicity and nucleophilicity of the oxygen atoms in the olivine compounds. The thermal stability of the LiMnPO4 material in solutions (measured by differential scanning calorimetry) is much higher compared to that of transition-metal oxide cathodes. This is demonstrated herein by a comparison with NCA electrodes. (C) 2009 The Electrochemical Society. [DOI: 10.1149/1.3125765] All rights reserved.

Antibacterial properties of an in situ generated and simultaneously deposited nanocrystalline ZnO on fabrics.

Abstract: Zinc oxide (ZnO) nanoparticles were synthesized and deposited on the surface of cotton fabrics using ultrasound irradiation. Optimization of the process resulted in a homogeneous distribution of ZnO nanocrystals, 30 nm in size, on the fabric surface. The mechanism of the ultrasound-assisted coating was proposed. The antibacterial activities of the ZnO−fabric composite were tested against Escherichia coli (Gram negative) and Staphylococcus aureus (Gram positive) cultures. A significant bactericidal effect, even in a 0.75% coated fabric (wt %), was demonstrated.

LiMn0.8Fe0.2PO4: An Advanced Cathode Material for Rechargeable Lithium Batteries

Abstract: Keywords: cathode materials ; lithium batteries ; nanoparticles ; surface chemistry ; thermal stability ; Performance ; Electrodes Reference EPFL-ARTICLE-159236doi:10.1002/anie.200903587View record in Web of Science Record created on 2010-11-30, modified on 2017-05-12