Showing papers by "Ben-Gurion University of the Negev published in 2007"

Smooth sensitivity and sampling in private data analysis

Abstract: We introduce a new, generic framework for private data analysis.The goal of private data analysis is to release aggregate information about a data set while protecting the privacy of the individuals whose information the data set contains.Our framework allows one to release functions f of the data withinstance-based additive noise. That is, the noise magnitude is determined not only by the function we want to release, but also bythe database itself. One of the challenges is to ensure that the noise magnitude does not leak information about the database. To address that, we calibrate the noise magnitude to the smoothsensitivity of f on the database x --- a measure of variabilityof f in the neighborhood of the instance x. The new frameworkgreatly expands the applicability of output perturbation, a technique for protecting individuals' privacy by adding a smallamount of random noise to the released statistics. To our knowledge, this is the first formal analysis of the effect of instance-basednoise in the context of data privacy.Our framework raises many interesting algorithmic questions. Namely,to apply the framework one must compute or approximate the smoothsensitivity of f on x. We show how to do this efficiently for several different functions, including the median and the cost ofthe minimum spanning tree. We also give a generic procedure based on sampling that allows one to release f(x) accurately on manydatabases x. This procedure is applicable even when no efficient algorithm for approximating smooth sensitivity of f is known orwhen f is given as a black box. We illustrate the procedure by applying it to k-SED (k-means) clustering and learning mixtures of Gaussians.

Early Adolescents' Perceptions of the Classroom Social Environment, Motivational Beliefs, and Engagement.

Abstract: This research examined whether 5th-grade students' (N = 602) perceptions of the classroom social environment (teacher support, promotion of mutual respect, promotion of task-related interaction, student support) were related to their engagement in the classroom (self-regulation and task-related interaction) and whether those relations were mediated by personal motivational beliefs (mastery goals, academic and social efficacy). Teacher support, promotion of interaction, and student support were related to both types of engagement, and those relations were fully or partially mediated by motivational beliefs. Relations with promoting mutual respect were not significant.

Variability in the clinical pattern of cutaneous side‐effects of drugs with systemic symptoms: does a DRESS syndrome really exist?

Abstract: ulceration. Dis Colon Rectum 2005; 48:1442–6. 4 Egred M, Andron M, Morrison WL. Nicorandil may be associated with gastrointestinal ulceration. BMJ 2006; 332:889. 5 King PM, Suttie SA, Jansen JO, Watson AJM. Perforation of the terminal ileum: a possible complication of nicorandil therapy. Surgeon 2004; 2:56–7. 6 Watson A, Al-Ozairi O, Fraser A et al. Nicorandil associated anal ulceration. Lancet 2002; 360:546–7.

The Contributions and Prospects of Goal Orientation Theory.

Abstract: In the last two decades, goal orientation theory has become an important perspective in the field of achievement motivation, and particularly in academic motivation. However, as research in the theory has proliferated, the use of multiple methods to assess goal orientations seems to have contributed to theoretical vagueness, especially with regard to the origin, development, and stability of these orientations. This review article starts with a critique of methods used in goal orientation research. The article then suggests six possible theoretical models of goal orientations that seem to be suggested by the literature, including the perspectives of goal orientations as emerging from: situation-schemas, self-schemas, self-prime, needs, values, and situated meaning-making processes. The article concludes with pointing to convergent findings, implications for practice, and persisting as well as emerging issues for future research.

Motivation to Lead, Motivation to Follow: The Role of the Self-Regulatory Focus in Leadership Processes

Abstract: In this paper we integrate recent theories of motivation and leadership. Drawing on the self-regulatory focus theory and on self-concept based theories of leadership, we develop a conceptual framework proposing that leaders' chronic self-regulatory focus (promotion versus prevention), in conjunction with their values, influences their motivation to lead and, subsequently, their leadership behavior. We further suggest that leaders may influence the motivational self-regulatory foci of their followers, which will mediate different follower outcomes at the individual and group level.

Autonomous motivation for teaching: How self-determined teaching may lead to self-determined learning.

Abstract: This study examined teachers' experience of autonomous motivation for teaching and its correlates in teachers and students. It was hypothesized that teachers would perceive various motivations posited by E. L. Deci and R. M. Ryan's (2000) self-determination theory as falling along a continuum of autonomous motivation for teaching. Autonomous motivation for teaching was predicted to be associated positively with teachers' sense of personal accomplishment and negatively with emotional exhaustion. Most important, teachers' self-reported autonomous motivation for teaching was expected to promote students' self-reported autonomous motivation for learning by enhancing teachers' autonomy-supportive behavior, as indicated by students' reports. Results from a sample of 132 Israeli teachers and their 1,255 students were consistent with the hypotheses. Discussion focuses on the importance of the experience of autonomous motivation for teaching for teachers and students.

An enhanced MITOMAP with a global mtDNA mutational phylogeny.

Abstract: The MITOMAP (http://www.mitomap.org) data system for the human mitochondrial genome has been greatly enhanced by the addition of a navigable mutational mitochondrial DNA (mtDNA) phylogenetic tree of 3000 mtDNA coding region sequences plus expanded pathogenic mutation tables and a nuclear-mtDNA pseudogene (NUMT) data base. The phylogeny reconstructs the entire mutational history of the human mtDNA, thus defining the mtDNA haplogroups and differentiating ancient from recent mtDNA mutations. Pathogenic mutations are classified by both genotype and phenotype, and the NUMT sequences permits detection of spurious inclusion of pseudogene variants during mutation analysis. These additions position MITOMAP for the implementation of our automated mtDNA sequence analysis system, Mitomaster.

Bridging In-school and Out-of-school Learning: Formal, Non-Formal, and Informal Education

Abstract: The present paper thoroughly examines how one can effectively bridge in-school and out-of-school learning. The first part discusses the difficulty in defining out-of-school learning. It proposes to distinguish three types of learning: formal, informal, and non-formal. The second part raises the question of whether out-of-school learning should be dealt with in the in-school system, in view of the fact that we experience informal learning anyway as well as considering the disadvantages and difficulties teachers are confronted with when planning and carrying out scientific fieldtrips. The voices of the teachers, the students, and the non-formal institution staff are heard to provide insights into the problem. The third part discusses the cognitive and affective aspects of non-formal learning. The fourth part presents some models explaining scientific fieldtrip learning and based on those models, suggests a novel explanation. The fifth part offers some recommendations of how to bridge in and out-of-school learning. The paper closes with some practical ideas as to how one can bring the theory described in the paper into practice. It is hoped that this paper will provide educators with an insight so that they will be able to fully exploit the great potential that scientific field trips may offer.

Macrophage infiltration into omental versus subcutaneous fat across different populations: effect of regional adiposity and the comorbidities of obesity.

Abstract: Context: Macrophage infiltration into adipose tissue has been demonstrated to accompany obesity, with a potential preferential infiltration into intraabdominal vs. sc fat. Objective: Our objective was to determine whether this occurs across different populations with a range of body mass indexes and to assess the relationship with regional adiposity and comorbidity of obesity. Setting and Patients: In two independent cohorts, we used paired omental (OM) and sc fat biopsies from lean controls or predominantly sc or intraabdominally obese persons with minimal comorbidity (n = 60, cohort 1), or from severely obese women with a significant rate of comorbidity (n = 29, cohort 2). Results: Elevated macrophage infiltration into OM vs. sc fat was observable in lean subjects and exaggerated by obesity, particularly if predominantly intraabdominal. This was paralleled by increased monocyte chemoattractant protein-1 (MCP1) and colony-stimulating factor-1 (CSF1) mRNA levels. Level of CSF1 and MCP1 mRNA correlated wit...

TGF-β receptor-mediated albumin uptake into astrocytes is involved in neocortical epileptogenesis

Abstract: It has long been recognized that insults to the cerebral cortex, such as trauma, ischaemia or infections, may result in the development of epilepsy, one of the most common neurological disorders. Human and animal studies have suggested that perturbations in neurovascular integrity and breakdown of the blood-brain barrier (BBB) lead to neuronal hypersynchronization and epileptiform activity, but the mechanisms underlying these processes are not known. In this study, we reveal a novel mechanism for epileptogenesis in the injured brain. We used focal neocortical, long-lasting BBB disruption or direct exposure to serum albumin in rats (51 and 13 animals, respectively, and 26 controls) as well as albumin exposure in brain slices in vitro. Most treated slices (72%, n = 189) displayed hypersynchronous propagating epileptiform field potentials when examined 5-49 days after treatment, but only 14% (n = 71) of control slices showed similar responses. We demonstrate that direct brain exposure to serum albumin is associated with albumin uptake into astrocytes, which is mediated by transforming growth factor beta receptors (TGF-betaRs). This uptake is followed by down regulation of inward-rectifying potassium (Kir 4.1) channels in astrocytes, resulting in reduced buffering of extracellular potassium. This, in turn, leads to activity-dependent increased accumulation of extracellular potassium, resulting in facilitated N-methyl-d-aspartate-receptor-mediated neuronal hyperexcitability and eventually epileptiform activity. Blocking TGF-betaR in vivo reduces the likelihood of epileptogenesis in albumin-exposed brains to 29.3% (n = 41 slices, P < 0.05). We propose that the above-described cascade of events following common brain insults leads to brain dysfunction and eventually epilepsy and suggest TGF-betaRs as a possible therapeutic target.

When Choice Motivates and When It Does Not

Abstract: This article addresses the controversy regarding the value of offering choices as a teaching practice. Inconsistent of results regarding the effects of choice in various settings suggest that choice can be either motivating or de-motivating. Based on the self-determination theory of motivation (Deci & Ryan, 2000), we propose that choice can be motivating when the options meet the students’ need for autonomy, competence, and relatedness. For example, choice is motivating when the options are relevant to the students’ interests and goals (autonomy support), are not too numerous or complex (competence support), and are congruent with the values of the students’ culture (relatedness support). Given the many factors involved, it is not surprising that in some studies choice was not found to promote engagement. However, when choice was offered in a way that met the needs of the students, it was found to enhance motivation, learning, and well-being.

Risk factors for acute generalized exanthematous pustulosis (AGEP)-results of a multinational case-control study (EuroSCAR).

Abstract: Background Acute generalized exanthematous pustulosis (AGEP) is a disease characterized by the rapid occurrence of many sterile, nonfollicular pustules usually arising on an oedematous erythema often accompanied by leucocytosis and fever. It is usually attributed to drugs. Objectives To evaluate the risk for different drugs of causing AGEP. Patients and methods A multinational case-control study (EuroSCAR) conducted to evaluate the risk for different drugs of causing severe cutaneous adverse reactions; the study included 97 validated community cases of AGEP and 1009 controls. Results Strongly associated drugs, i.e. drugs with a lower bound of the 95% confidence interval (CI) of the odds ratio (OR) > 5 were pristinamycin (CI 26-infinity), ampicillin/amoxicillin (CI 10-infinity), quinolones (CI 8.5-infinity), (hydroxy)chloroquine (CI 8-infinity), anti-infective sulphonamides (CI 7.1-infinity), terbinafine (CI 7.1-infinity) and diltiazem (CI 5.0-infinity). No significant risk was found for infections and a personal or family history of psoriasis (CI 0.7-2.2). Conclusions Medications associated with AGEP differ from those associated with Stevens-Johnson syndrome or toxic epidermal necrolysis. Different timing patterns from drug intake to reaction onset were observed for different drugs. Infections, although possible triggers, played no prominent role in causing AGEP and there was no evidence that AGEP is a variant of pustular psoriasis.

Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy in the Management of Peritoneal Surface Malignancies of Colonic Origin: A Consensus Statement

Abstract: Cytoreductive surgery and hyperthermic intraperitoneal chemotherapy in the management of peritoneal surface malignancies of colonic origin : a consensus statement

Evaluation of a cellular phone-based system for measurements of traffic speeds and travel times: A case study from Israel

Abstract: The purpose of this paper is to examine the performance of a new operational system for measuring traffic speeds and travel times which is based on information from a cellular phone service provider. Cellular measurements are compared with those obtained by dual magnetic loop detectors. The comparison uses data for a busy 14 km freeway with 10 interchanges, in both directions, during January–March of 2005. The dataset contains 1 284 587 valid loop detector speed measurements and 440 331 valid measurements from the cellular system, each measurement referring to a 5 min interval. During one week in this period, 25 floating car measurements were conducted as additional comparison observations. The analyses include visual, graphical, and statistical techniques; focusing in particular on comparisons of speed patterns in the time–space domain. The main finding is that there is a good match between the two measurement methods, indicating that the cellular phone-based system can be useful for various practical applications such as advanced traveler information systems and evaluating system performance for modeling and planning. 2007 Elsevier Ltd. All rights reserved.

Modeling and Analysis of Thermoelectric Modules

Abstract: The objective of this paper is to develop a SPICE- compatible equivalent circuit of a thermoelectric module. A methodology is developed for extracting the parameters of the proposed model from manufacturers' data of thermoelectric coolers (TECs) and thermoelectric generators (TEGs). The model could be helpful in analyzing the drive requirements of TECs and loading effects of TEGs. The present model is compatible with PSPICE or other electric circuit simulators. An important feature of the model is its ability to generate small-signal transfer functions that can be used to design feedback networks for temperature control applications

Electro-osmotic slip and electroconvective instability

Abstract: Electric conduction from an electrolyte solution into a charge selective solid, such as ion exchange membrane or electrode, becomes unstable when the electrolyte concentration near the interface approaches zero owing to diffusion limitation. The sequence of events leading to instability is as follows: upon the decrease of the interface concentration, the electric double layer at the interface transforms from its common quasi-equilibrium structure to a different, non-equilibrium one. The key feature of this new structure is an extended space charge added to the usual one of the quasi-equilibrium electric double layer. The non-equilibrium electro-osmotic slip related to this extended space charge renders the quiescent conductance unstable. A unified asymptotic picture of the electric double-layer undercurrent, encompassing all regimes from quasi-equilibrium to the extreme non-equilibrium one, is developed and employed for derivation of a universal electro-osmotic slip formula. This formula is used for a linear stability study of quiescent electric conduction, yielding the precise parameter range of instability, compared with that in the full electroconvective formulation. The physical mechanism of instability is traced both kinematically, in terms of non-equilibrium electro-osmotic slip, and dynamically, in terms of forces acting in the electric double layer.

Linear matrix inequality representation of sets

Abstract: This article concerns the question, Which subsets of ℝm can be represented with linear matrix inequalities (LMIs)? This gives some perspective on the scope and limitations of one of the most powerful techniques commonly used in control theory. Also, before having much hope of representing engineering problems as LMIs by automatic methods, one needs a good idea of which problems can and cannot be represented by LMIs. Little is currently known about such problems. In this article we give a necessary condition that we call “rigid convexity,” which must hold for a set ⊆ ℝm in order for to have an LMI representation. Rigid convexity is proved to be necessary and sufficient when m = 2. This settles a question formally stated by Pablo Parrilo and Berndt Sturmfels in [15]. As shown by Lewis, Parillo, and Ramana [11], our main result also establishes (in the case of three variables) a 1958 conjecture by Peter Lax on hyperbolic polynomials. © 2006 Wiley Periodicals, Inc.

The associative memory deficit of older adults: the role of strategy utilization.

Abstract: Past research has established an associative deficit hypothesis (e.g., M. Naveh-Benjamin, 2000) that attributes part of older adults' poor episodic memory performance to their difficulty in creating and retrieving cohesive episodes. Here, the authors evaluate the degree to which this deficit can be reduced by older adults' use of associative strategies. Young and older adults learned word pairs under either intentional-learning instructions or instructions eliciting associative strategies either at encoding or both at encoding and at retrieval, and they then took tests on their memory for both the components and the associations. Results replicated the associative deficit of older adults under intentional-learning instructions. In addition, they showed that instructions to use appropriate associative strategies during either encoding or, even more so, during encoding and retrieval resulted in a significant decrease in the associative deficit. The theoretical and applied implications of these results are discussed.

Inequality and Institutions

Abstract: This paper presents theory and evidence on the relationship between inequality and institutional quality. We exhibit a model in which the two may dynamically reinforce each other and set to test this relationship with a broad array of institutional measures. The double causality between institutional strength and a more equal distribution of income is empirically established using dynamic panel and linear feedback analysis.

Nature of the superconductor-insulator transition in disordered superconductors.

Abstract: As a superconducting thin film becomes disordered and subject to an increasing magnetic field, a point is reached when it undergoes a transition from a superconducting to an insulating state. Dubi et al. use numerical simulations to study this transition — or, as it turns out, two types of transition. The key effect of disorder is to create 'islands' of strong superconductivity, coupled by regions that are only weakly superconducting. In the case of weak disorder, an increasing magnetic field eventually destroys the superconducting state throughout the material, leading to an insulator. When disorder is strong, superconductivity persists in the islands, and the effect of a magnetic field is to suppress the coupling between them — again leading to an insulating state. These findings may be relevant to the high-temperature superconductors, where intrinsic disorder may play a role. As a superconducting thin film is made more disordered, or subject to an increasing magnetic field, a point is reached when the material undergoes a transition from a superconducting to an insulating state. Numerical simulations have been used to shed light on the nature of this transition, or, as it turns out, two types of transition. The interplay of superconductivity and disorder has intrigued scientists for several decades. Disorder is expected to enhance the electrical resistance of a system, whereas superconductivity is associated with a zero-resistance state. Although superconductivity has been predicted to persist even in the presence of disorder1, experiments performed on thin films have demonstrated a transition from a superconducting to an insulating state with increasing disorder or magnetic field2. The nature of this transition is still under debate, and the subject has become even more relevant with the realization that high-transition-temperature (high-Tc) superconductors are intrinsically disordered3,4,5. Here we present numerical simulations of the superconductor–insulator transition in two-dimensional disordered superconductors, starting from a microscopic description that includes thermal phase fluctuations. We demonstrate explicitly that disorder leads to the formation of islands where the superconducting order is high. For weak disorder, or high electron density, increasing the magnetic field results in the eventual vanishing of the amplitude of the superconducting order parameter, thereby forming an insulating state. On the other hand, at lower electron densities or higher disorder, increasing the magnetic field suppresses the correlations between the phases of the superconducting order parameter in different islands, giving rise to a different type of superconductor–insulator transition. One of the important predictions of this work is that in the regime of high disorder, there are still superconducting islands in the sample, even on the insulating side of the transition. This result, which is consistent with experiments6,7, explains the recently observed huge magneto-resistance peak in disordered thin films8,9,10 and may be relevant to the observation of ‘the pseudogap phenomenon’ in underdoped high-Tc superconductors11,12.

Interleukin-1β–Driven Inflammation Promotes the Development and Invasiveness of Chemical Carcinogen–Induced Tumors

Abstract: The role of microenvironment interleukin 1 (IL-1) on 3-methylcholanthrene (3-MCA)-induced carcinogenesis was assessed in IL-1-deficient mice, i.e., IL-1beta(-/-), IL-1alpha(-/-), IL-1alpha/beta(-/-) (double knockout), and mice deficient in the naturally occurring inhibitor of IL-1, the IL-1 receptor antagonist (IL-1Ra). Tumors developed in all wild-type (WT) mice, whereas in IL-1beta-deficient mice, tumors developed slower and only in some of the mice. In IL-1Ra-deficient mice, tumor development was the most rapid. Tumor incidence was similar in WT and IL-1alpha-deficient mice. Histologic analyses revealed fibrotic structures forming a capsule surrounding droplets of the carcinogen in olive oil, resembling foreign body-like granulomas, which appeared 10 days after injection of 3-MCA and persisted until the development of local tumors. A sparse leukocyte infiltrate was found at the site of carcinogen injection in IL-1beta-deficient mice, whereas in IL-1Ra-deficient mice, a dense neutrophilic infiltrate was observed. Treatment of IL-1Ra-deficient mice with recombinant IL-1Ra but not with an inhibitor of tumor necrosis factor abrogated the early leukocytic infiltrate. The late leukocyte infiltrate (day 70), which was dominated by macrophages, was also apparent in WT and IL-1alpha-deficient mice, but was nearly absent in IL-1beta-deficient mice. Fibrosarcoma cell lines, established from 3-MCA-induced tumors from IL-1Ra-deficient mice, were more aggressive and metastatic than lines from WT mice; cell lines from IL-1-deficient mice were the least invasive. These observations show the crucial role of microenvironment-derived IL-1beta, rather than IL-1alpha, in chemical carcinogenesis and in determining the invasive potential of malignant cells.

Gaining Agility through IT Personnel Capabilities: The Mediating Role of IT Infrastructure Capabilities *

Abstract: This study develops a research model of how the technical, behavioral, and business capabilities of IT personnel are associated with IT infrastructure capabilities, and how the latter are associated with IT-dependent organizational agility, which is conceptualized as comprising IT-dependent system, information, and strategic agility. Analysis of crosssectional data collected from 293 IT managers generally corroborates the hypothesized relationships, showing that the technical and behavioral capabilities of IT personnel have a positive effect on infrastructure capabilities. The analysis also provides evidence that the effect of infrastructure capabilities on IT-dependent strategic agility is direct, as well as mediated by IT-dependent system and information agility. The validity of the findings is strengthened by demonstrating that the hypothesized research model fits the data better than two alternative theoretically-anchored models describing different relationships between the same constructs. This study advances understanding of the interrelationships between two major subsets of IT capabilities, and their relationships with the agility afforded by IT.