Showing papers by "Tel Aviv University published in 2004"

Export Versus FDI with Heterogeneous Firms

Abstract: Multinational sales have grown at high rates over the last two decades, outpacing the remarkable expansion of trade in manufactures. Consequently, the trade literature has sought to incorporate the mode of foreign market access into the “new” trade theory. This literature recognizes that Ž rms can serve foreign buyers through a variety of channels: they can export their products to foreign customers, serve them through foreign subsidiaries, or license foreign Ž rms to produce their products. Our work focuses on the Ž rm’s choice between exports and “horizontal” foreign direct investment (FDI). Horizontal FDI refers to an investment in a foreign production facility that is designed to serve customers in the foreign market. Firms invest abroad when the gains from avoiding trade costs outweigh the costs of maintaining capacity in multiple markets. This is known as the proximity-concentration tradeoff. We introduce heterogeneous Ž rms into a simple multicountry, multisector model, in which Ž rms face a proximity-concentration trade-off. Every Ž rm decides whether to serve a foreign market, and whether to do so through exports or local subsidiary sales. These modes of market access have different relative costs: exporting involves lower Ž xed costs while FDI involves lower variable costs. Our model highlights the important role of within-sector Ž rm productivity differences in explaining the structure of international trade and investment. First, only the most productive Ž rms engage in foreign activities. This result mirrors other Ž ndings on Ž rm heterogeneity and trade; in particular, the results reported in Melitz (2003). Second, of those Ž rms that serve foreign markets, only the most productive engage in FDI. Third, FDI sales relative to exports are larger in sectors with more Ž rm heterogeneity. Using U.S. exports and afŽ liate sales data that cover 52 manufacturing sectors and 38 countries, we show that cross-sectoral differences in Ž rm heterogeneity predict the composition of trade and investment in the manner suggested by our model. We construct several measures of Ž rm heterogeneity, using different data sources, and show that our results are robust across all these measures. In addition, we conŽ rm the predictions of the proximityconcentration trade-off. That is, Ž rms tend to substitute FDI sales for exports when transport * Helpman: Department of Economics, Harvard University, Cambridge, MA 02138, Tel Aviv University, and CIAR (e-mail: ehelpman@harvard.edu); Melitz: Department of Economics, Harvard University, Cambridge, MA 02138, National Bureau of Economic Research, and Centre for Economic Policy Research (e-mail: mmelitz@ harvard.edu); Yeaple: Department of Economics, University of Pennsylvania, 3718 Locust Walk, Philadelphia, PA 19104, and National Bureau of Economic Research (e-mail: snyeapl2@ssc.upenn.edu). The statistical analysis of Ž rmlevel data on U.S. Multinational Corporations reported in this study was conducted at the International Investment Division, U.S. Bureau of Economic Analysis, under an arrangement that maintained legal conŽ dentiality requirements. Views expressed are those of the authors and do not necessarily re ect those of the Bureau of Economic Analysis. Elhanan Helpman thanks the NSF for Ž nancial support. We also thank Daron Acemoglu, Roberto Rigobon, Yona Rubinstein, and Dani Tsiddon for comments on an earlier draft, and Man-Keung Tang for excellent research assistance. 1 See Wilfred J. Ethier (1986), Ignatius Horstmann and James R. Markusen (1987), and Ethier and Markusen (1996) for models that incorporate the licensing alternative. We therefore exclude “vertical” motives for FDI that involve fragmentation of production across countries. See Helpman (1984, 1985), Markusen (2002, Ch. 9), and Gordon H. Hanson et al. (2002) for treatments of this form of FDI. 3 See, for example, Horstmann and Markusen (1992), S. Lael Brainard (1993), and Markusen and Anthony J. Venables (2000). 4 See also Andrew B. Bernard et al. (2003) for an alternative theoretical model and Yeaple (2003a) for a model based on worker-skill heterogeneity. James R. Tybout (2003) surveys the recent micro-level evidence on trade that has motivated these theoretical models. 5 This result is loosely connected to the documented empirical pattern that foreign-owned afŽ liates are more productive than domestically owned producers. See Mark E. Doms and J. Bradford Jensen (1998) for the United States and Sourafel Girma et al. (2002) for the United Kingdom.

The restaurant at the end of the random walk: recent developments in the description of anomalous transport by fractional dynamics

Abstract: Fractional dynamics has experienced a firm upswing during the past few years, having been forged into a mature framework in the theory of stochastic processes. A large number of research papers developing fractional dynamics further, or applying it to various systems have appeared since our first review article on the fractional Fokker–Planck equation (Metzler R and Klafter J 2000a, Phys. Rep. 339 1–77). It therefore appears timely to put these new works in a cohesive perspective. In this review we cover both the theoretical modelling of sub- and superdiffusive processes, placing emphasis on superdiffusion, and the discussion of applications such as the correct formulation of boundary value problems to obtain the first passage time density function. We also discuss extensively the occurrence of anomalous dynamics in various fields ranging from nanoscale over biological to geophysical and environmental systems.

Central masses and broad-line region sizes of active galactic nuclei. ii. a homogeneous analysis of a large reverberation-mapping database

Abstract: We present improved black hole masses for 35 active galactic nuclei (AGNs) based on a complete and consistent reanalysis of broad emission-line reverberation-mapping data From objects with multiple line measurements, we find that the highest precision measure of the virial product cτΔV2/G, where τ is the emission-line lag relative to continuum variations and ΔV is the emission-line width, is obtained by using the cross-correlation function centroid (as opposed to the cross-correlation function peak) for the time delay and the line dispersion (as opposed to FWHM) for the line width and by measuring the line width in the variable part of the spectrum Accurate line-width measurement depends critically on avoiding contaminating features, in particular the narrow components of the emission lines We find that the precision (or random component of the error) of reverberation-based black hole mass measurements is typically around 30%, comparable to the precision attained in measurement of black hole masses in quiescent galaxies by gas or stellar dynamical methods Based on results presented in a companion paper by Onken et al, we provide a zero-point calibration for the reverberation-based black hole mass scale by using the relationship between black hole mass and host-galaxy bulge velocity dispersion The scatter around this relationship implies that the typical systematic uncertainties in reverberation-based black hole masses are smaller than a factor of 3 We present a preliminary version of a mass-luminosity relationship that is much better defined than any previous attempt Scatter about the mass-luminosity relationship for these AGNs appears to be real and could be correlated with either Eddington ratio or object inclination

Intersubject Synchronization of Cortical Activity During Natural Vision

Abstract: To what extent do all brains work alike during natural conditions? We explored this question by letting five subjects freely view half an hour of a popular movie while undergoing functional brain imaging. Applying an unbiased analysis in which spatiotemporal activity patterns in one brain were used to “model” activity in another brain, we found a striking level of voxel-by-voxel synchronization between individuals, not only in primary and secondary visual and auditory areas but also in association cortices. The results reveal a surprising tendency of individual brains to “tick collectively” during natural vision. The intersubject synchronization consisted of a widespread cortical activation pattern correlated with emotionally arousing scenes and regionally selective components. The characteristics of these activations were revealed with the use of an open-ended “reverse-correlation” approach, which inverts the conventional analysis by letting the brain signals themselves “pick up” the optimal stimuli for each specialized cortical area.

Laplacian surface editing

Abstract: Surface editing operations commonly require geometric details of the surface to be preserved as much as possible. We argue that geometric detail is an intrinsic property of a surface and that, consequently, surface editing is best performed by operating over an intrinsic surface representation. We provide such a representation of a surface, based on the Laplacian of the mesh, by encoding each vertex relative to its neighborhood. The Laplacian of the mesh is enhanced to be invariant to locally linearized rigid transformations and scaling. Based on this Laplacian representation, we develop useful editing operations: interactive free-form deformation in a region of interest based on the transformation of a handle, transfer and mixing of geometric details between two surfaces, and transplanting of a partial surface mesh onto another surface. The main computation involved in all operations is the solution of a sparse linear system, which can be done at interactive rates. We demonstrate the effectiveness of our approach in several examples, showing that the editing operations change the shape while respecting the structural geometric detail.

Two-dimensional strain-a novel software for real-time quantitative echocardiographic assessment of myocardial function.

Abstract: Objectives We sought to assess the feasibility of 2-dimensional strain, a novel software for real-time quantitative echocardiographic assessment of myocardial function Methods Conventional and a novel non-Doppler–based echocardiography technique for advanced wall-motion analysis were performed in 20 patients with myocardial infarction and 10 healthy volunteers from the apical views Two-dimensional strain is on the basis of the estimation that a discrete set of tissue velocities are present per each of many small elements on the ultrasound image This software permits real-time assessment of myocardial velocities, strain, and strain rate These parameters were also compared with Doppler tissue imaging measurements in 10 additional patients Results In all, 803% of infarct and 978% of normal segments could be adequately tracked by the software Peak systolic strain, strain rate, and peak systolic myocardial velocities, calculated from the software, were significantly higher in the normal than in the infarct segments In the 10 additional patients, velocities, strain, and strain rate obtained with the novel software were not significantly different from those obtained with Doppler tissue imaging Conclusion Two-dimensional strain can accomplish real-time wall-motion analysis, and has the potential to become a standard for real-time automatic echocardiographic assessment of cardiac function

Falls and freezing of gait in Parkinson's disease : a review of two interconnected, episodic phenomena

Abstract: Falls and freezing of gait are two "episodic" phenomena that are common in Parkinson's disease. Both symptoms are often incapacitating for affected patients, as the associated physical and psychosocial consequences have a great impact on the patients' quality of life, and survival is diminished. Furthermore, the resultant loss of independence and the treatment costs of injuries add substantially to the health care expenditures associated with Parkinson's disease. In this clinically oriented review, we summarise recent insights into falls and freezing of gait and highlight their similarities, differences, and links. Topics covered include the clinical presentation, recent ideas about the underlying pathophysiology, and the possibilities for treatment. A review of the literature and the current state-of-the-art suggests that clinicians should not feel deterred by the complex nature of falls and freezing of gait; a careful clinical approach may lead to an individually tailored treatment, which can offer at least partial relief for many affected patients.

The Cellulosomes: Multienzyme Machines for Degradation of Plant Cell Wall Polysaccharides

Abstract: The discrete multicomponent, multienzyme cellulosome complex of anaerobic cellulolytic bacteria provides enhanced synergistic activity among the different resident enzymes to efficiently hydrolyze intractable cellulosic and hemicellulosic substrates of the plant cell wall. A pivotal noncatalytic subunit called scaffoldin secures the various enzymatic subunits into the complex via the cohesin-dockerin interaction. The specificity characteristics and tenacious binding between the scaffoldin-based cohesin modules and the enzyme-borne dockerin domains dictate the supramolecular architecture of the cellulosome. The diversity in cellulosome architecture among the known cellulosome-producing bacteria is manifest in the arrangement of their genes in either multiple-scaffoldin or enzyme-linked clusters on the genome. The recently described three-dimensional crystal structure of the cohesin-dockerin heterodimer sheds light on the critical amino acids that contribute to this high-affinity protein-protein interaction. In addition, new information regarding the regulation of cellulosome-related genes, budding genetic tools, and emerging genomics of cellulosome-producing bacteria promises new insight into the assembly and consequences of the multienzyme complex.

Achieving 1/2 log (1+SNR) on the AWGN channel with lattice encoding and decoding

Abstract: We address an open question, regarding whether a lattice code with lattice decoding (as opposed to maximum-likelihood (ML) decoding) can achieve the additive white Gaussian noise (AWGN) channel capacity We first demonstrate how minimum mean-square error (MMSE) scaling along with dithering (lattice randomization) techniques can transform the power-constrained AWGN channel into a modulo-lattice additive noise channel, whose effective noise is reduced by a factor of /spl radic/(1+SNR/SNR) For the resulting channel, a uniform input maximizes mutual information, which in the limit of large lattice dimension becomes 1/2 log (1+SNR), ie, the full capacity of the original power constrained AWGN channel We then show that capacity may also be achieved using nested lattice codes, the coarse lattice serving for shaping via the modulo-lattice transformation, the fine lattice for channel coding We show that such pairs exist for any desired nesting ratio, ie, for any signal-to-noise ratio (SNR) Furthermore, for the modulo-lattice additive noise channel lattice decoding is optimal Finally, we show that the error exponent of the proposed scheme is lower bounded by the Poltyrev exponent

Is allostery an intrinsic property of all dynamic proteins

Abstract: Allostery involves coupling of conformational changes between two widely separated binding sites. The common view holds that allosteric proteins are symmetric oligomers, with each subunit existing in "at least" two conformational states with a different affinity for ligands. Recent observations such as the allosteric behavior of myoglobin, a classical example of a nonallosteric protein, call into question the existing allosteric dogma. Here we argue that all (nonfibrous) proteins are potentially allosteric. Allostery is a consequence of re-distributions of protein conformational ensembles. In a nonallosteric protein, the binding site shape may not show a concerted second-site change and enzyme kinetics may not reflect an allosteric transition. Nevertheless, appropriate ligands, point mutations, or external conditions may facilitate a population shift, leading a presumably nonallosteric protein to behave allosterically. In principle, practically any potential drug binding to the protein surface can alter the conformational redistribution. The question is its effectiveness in the redistribution of the ensemble, affecting the protein binding sites and its function. Here, we review experimental observations validating this view of protein allostery.

Epidemiology of gestational diabetes mellitus and its association with Type 2 diabetes.

Abstract: Gestational diabetes (GDM) is defined as carbohydrate intolerance that begins or is first recognized during pregnancy. Although it is a well-known cause of pregnancy complications, its epidemiology has not been studied systematically. Our aim was to review the recent data on the epidemiology of GDM, and to describe the close relationship of GDM to prediabetic states, in addition to the risk of future deterioration in insulin resistance and development of overt Type 2 diabetes. We found that differences in screening programmes and diagnostic criteria make it difficult to compare frequencies of GDM among various populations. Nevertheless, ethnicity has been proven to be an independent risk factor for GDM, which varies in prevalence in direct proportion to the prevalence of Type 2 diabetes in a given population or ethnic group. There are several identifiable predisposing factors for GDM, and in the absence of risk factors, the incidence of GDM is low. Therefore, some authors suggest that selective screening may be cost-effective. Importantly, women with an early diagnosis of GDM, in the first half of pregnancy, represent a high-risk subgroup, with an increased incidence of obstetric complications, recurrent GDM in subsequent pregnancies, and future development of Type 2 diabetes. Other factors that place women with GDM at increased risk of Type 2 diabetes are obesity and need for insulin for glycaemic control. Furthermore, hypertensive disorders in pregnancy and afterwards may be more prevalent in women with GDM. We conclude that the epidemiological data suggest an association between several high-risk prediabetic states, GDM, and Type 2 diabetes. Insulin resistance is suggested as a pathogenic linkage. It is possible that improving insulin sensitivity with diet, exercise and drugs such as metformin may reduce the risk of diabetes in individuals at high risk, such as women with polycystic ovary syndrome, impaired glucose tolerance, and a history of GDM. Large controlled studies are needed to clarify this issue and to develop appropriate diabetic prevention strategies that address the potentially modifiable risk factors.

Systematic identification of abundant A-to-I editing sites in the human transcriptome

Abstract: RNA editing by members of the ADAR (adenosine deaminases acting on RNA) family leads to site-specific conversion of adenosine to inosine (A-to-I) in precursor messenger RNAs. Editing by ADARs is believed to occur in all metazoa, and is essential for mammalian development. Currently, only a limited number of human ADAR substrates are known, whereas indirect evidence suggests a substantial fraction of all pre-mRNAs being affected. Here we describe a computational search for ADAR editing sites in the human transcriptome, using millions of available expressed sequences. We mapped 12,723 A-to-I editing sites in 1,637 different genes, with an estimated accuracy of 95%, raising the number of known editing sites by two orders of magnitude. We experimentally validated our method by verifying the occurrence of editing in 26 novel substrates. A-to-I editing in humans primarily occurs in noncoding regions of the RNA, typically in Alu repeats. Analysis of the large set of editing sites indicates the role of editing in controlling dsRNA stability.

A Brief Screening Questionnaire for Infant Sleep Problems: Validation and Findings for an Internet Sample

Abstract: Objective. To develop and validate (using subjective and objective methods) a brief infant sleep questionnaire (BISQ) that would be appropriate for screening in pediatric settings. Design. Two studies were performed to assess the properties of the BISQ. Study I compared BISQ measures with sleep diary measures and objective actigraphic sleep measures for clinical ( N = 43) and control ( N = 57) groups of infants (5–29 months of age). The second study was based on an Internet survey of 1028 respondents who completed the BISQ posted on an infant sleep web site. Results. In study I, BISQ measures were found to be correlated significantly with sleep measures derived from actigraphy and sleep diaries. BISQ measures (number of night wakings and nocturnal sleep duration) were the best predictors for distinguishing between clinical and control samples. High test-retest correlations ( r > .82) were demonstrated for BISQ measures for a subsample of 26 infants. Study II provided a developmental perspective on BISQ measures. The study demonstrated that BISQ measures derived from a large Internet survey provided developmental and sleep ecology-related findings that corresponded to the existing literature findings on sleep patterns in early childhood. Conclusions. The findings provide psychometric, clinical, and ecologic support for the use of the BISQ as a brief infant sleep screening tool for clinical and research purposes. Potential clinical cutoff scores are provided.

The relationships between intangible organizational elements and organizational performance

Abstract: Despite the growing awareness of the importance of researching core strategic resources and activities, the work that has been done to date has largely taken the form of anecdotal reports and case study analysis. We have yet to see large-sample studies demonstrating how organizational elements, independently, complementarily and interactively, may or may not enhance the organization's performance. Moreover, little attention has been given to researching this topic in public sector organizations. The present study aims to bridge this gap by examining the impact of a set of independent intangible organizational elements and the interactions among them on a set of objective organizational performance measures in a sample of local government authorities in Israel. The results of a multivariate analysis indicate that organizational performance (measured by self-income ratio, collecting efficiency ratio, employment rate, and municipal development) can be well explained by six intangible organizational elements (managerial capabilities, human capital, internal auditing, labor relations, organizational culture, and perceived organizational reputation) and the interactions among them, which need to be taken into account in any cost effective development. Copyright © 2004 John Wiley & Sons, Ltd.

Attogram detection using nanoelectromechanical oscillators

Abstract: We report on the fabrication of nanometer-scale mass sensors with subattogram sensitivity. Surface micromachined polycrystalline silicon and silicon nitride nanomechanical oscillators were used to detect the presence of well-defined mass loading. Controlled deposition of thiolate self-assembled monolayers on lithographically defined gold dots were used for calibrated mass loading. We used a dinitrophenyl poly(ethylene glycol) undecanthiol-based molecule (DNP-PEG4-C11thiol) as a model ligand for this study. Due to the fact that the gold mass is attached at the distance l0 from the end x=l of the cantilever beam, an additional moment evolves in the boundary condition of the oscillator, which was taken into consideration through the rotational inertia of the attached mass. We showed that the corresponding correction of the frequency is on the order of γ(l0/l), where γ is the attached mass normalized to the mass of the beam. The rotational inertia correction to the frequency is on the order of γ(l0/l)2. The a...

The nonlinear nature of friction

Abstract: Tribology is the study of adhesion, friction, lubrication and wear of surfaces in relative motion. It remains as important today as it was in ancient times, arising in the fields of physics, chemistry, geology, biology and engineering. The more we learn about tribology the more complex it appears. Nevertheless, recent experiments coupled to theoretical modelling have made great advances in unifying apparently diverse phenomena and revealed many subtle and often non-intuitive aspects of matter in motion, which stem from the nonlinear nature of the problem.

2010 International consensus algorithm for the diagnosis, therapy and management of hereditary angioedema

Abstract: C1 inhibitor deficiency (hereditary angioedema [HAE]) is a rare disorder for which there is a lack of consensus concerning diagnosis, therapy, and management, particularly in Canada. European initiatives have driven the approach to managing HAE with 3 C1-INH Deficiency Workshops held every 2 years in Hungary starting in 1999, with the third Workshop having recently been held in May 2003. The European Contact Board has established a European HAE Registry that will hopefully advance our knowledge of this disorder. The Canadian Hereditary Angioedema Society/Societe d'Angioedeme Hereditaire du Canada organized a Canadian International Consensus Conference held in Toronto, Ontario, Canada, on October 24 to 26, 2003, to foster consensus between major European and North American HAE treatment centers. Papers were presented by investigators from Europe and North America, and this consensus algorithm approach was discussed. There is a paucity of double-blind placebo-controlled trials in the treatment of HAE, making levels of evidence to support the algorithm less than optimal. Enclosed is the consensus algorithm approach recommended for the diagnosis, therapy, and management of HAE and agreed to by the authors of this article. This document is only a consensus algorithm approach and requires validation. As such, participants agreed to make this a living 2003 algorithm (ie, a work in progress) and agreed to review its content at future international HAE meetings. The consensus, however, has strength in that it was arrived at by the meeting of patient-care providers along with patient group representatives and individual patients reviewing information available to date and reaching agreement on how to approach the diagnosis, therapy, and management of HAE circa 2003. Hopefully evidence to support approaches to the management of HAE will approach the level of meta-analysis of randomized controlled trials in the near future.

The complex architecture of oxygenic photosynthesis.

Abstract: Oxygenic photosynthesis is the principal producer of both oxygen and organic matter on earth. The primary step in this process — the conversion of sunlight into chemical energy — is driven by four, multisubunit, membrane-protein complexes that are known as photosystem I, photosystem II, cytochrome b 6 f and F-ATPase. Structural insights into these complexes are now providing a framework for the exploration not only of energy and electron transfer, but also of the evolutionary forces that shaped the photosynthetic apparatus.

How did alternative splicing evolve

Abstract: Alternative splicing creates transcriptome diversification, possibly leading to speciation. A large fraction of the protein-coding genes of multicellular organisms are alternatively spliced, although no regulated splicing has been detected in unicellular eukaryotes such as yeasts. A comparative analysis of unicellular and multicellular eukaryotic 5' splice sites has revealed important differences - the plasticity of the 5' splice sites of multicellular eukaryotes means that these sites can be used in both constitutive and alternative splicing, and for the regulation of the inclusion/skipping ratio in alternative splicing. So, alternative splicing might have originated as a result of relaxation of the 5' splice site recognition in organisms that originally could support only constitutive splicing.

The Receptor for the Fungal Elicitor Ethylene-Inducing Xylanase Is a Member of a Resistance-Like Gene Family in Tomato

Abstract: An ethylene-inducing xylanase (EIX) is a potent elicitor of plant defense responses in specific cultivars of tobacco (Nicotiana tabacum) and tomato (Lycopersicon esculentum). The LeEix locus in tomatoes was characterized by map-based cloning, which led to the identification of a novel gene cluster from which two members (LeEix1 and LeEix2) were isolated. Similar to the tomato Ve resistance genes in tomato plants, the deduced amino acid sequences encoded by LeEix1 and LeEix2 contain a Leu zipper, an extracellular Leu-rich repeat domain with glycosylation signals, a transmembrane domain, and a C-terminal domain with a mammalian endocytosis signal. Silencing expression of the LeEix genes prevented the binding of EIX to cells of an EIX-responsive plant and thus inhibited the hypersensitive response. Overexpression of either LeEix1 or LeEix2 genes in EIX-nonresponsive tobacco plants enabled the binding of EIX, although only LeEix2 could transmit the signal that induced the hypersensitive response. Overexpressing LeEix2 in mammalian COS-7 cells enables binding of EIX, indicating physical interaction between the EIX elicitor and LeEix2 gene product. Structural analysis of the LeEix proteins suggests that they belong to a class of cell-surface glycoproteins with a signal for receptor-mediated endocytosis. Mutating the endocytosis signal in LeEix2 (Tyr 993 to Ala) abolished its ability to induce the hypersensitive response, suggesting that endocytosis plays a key role in the signal transduction pathway.

New modeling and experimental framework to characterize hindered and restricted water diffusion in brain white matter

Abstract: To characterize anisotropic water diffusion in brain white matter, a theoretical framework is proposed that combines hindered and restricted models of water diffusion (CHARMED) and an experimental methodology that embodies features of diffusion tensor and q-space MRI. This model contains a hindered extra-axonal compartment, whose diffusion properties are characterized by an effective diffusion tensor, and an intra-axonal compartment, whose diffusion properties are characterized by a restricted model of diffusion within cylinders. The hindered model primarily explains the Gaussian signal attenuation observed at low b values; the restricted non-Gaussian model does so at high b. Both high and low b data obtained along different directions are required to estimate various microstructural parameters of the composite model, such as the nerve fiber orientation(s), the T2-weighted extra- and intra-axonal volume fractions, and principal diffusivities. The proposed model provides a description of restricted diffusion in 3D given by a 3D probability distribution (average propagator), which is obtained by 3D Fourier transformation of the estimated signal attenuation profile. The new model is tested using synthetic phantoms and validated on excised spinal cord tissue. This framework shows promise in determining the orientations of two or more fiber compartments more precisely and accurately than with diffusion tensor imaging.

A Rational Look at the Emotional Stroop Phenomenon: A Generic Slowdown, Not a Stroop Effect.

Abstract: The role of Stroop processes in the emotional Stroop effect was subjected to a conceptual scrutiny augmented by a series of experiments entailing reading or lexical decision as well as color naming. The analysis showed that the Stroop effect is not defined in the emotional Stroop task. The experiments showed that reading, lexical decision, and color naming all are slower with emotional words and that this delay is immune to task-irrelevant variation and to changes in the relative salience of the words and the colors. The delay was absent when emotional and neutral words appeared in a single block. A threat-driven generic slowdown is implicated, not a selective attention mechanism associated with the classic Stroop effect.

Worst-case to average-case reductions based on Gaussian measures

Abstract: We show that solving modular linear equation on the average is at least as hard as approximating several lattice problems in the worst case within a factor almost linear in the rank of the lattice. The lattice problems we consider are the shortest vector problem, the shortest independent vectors problem and the covering radius problem. The approximation factor we obtain is O(n) for all three problems. This greatly improves on all previous work on the subject starting from Ajtai's seminal paper (STOC, 1996), up to the strongest previously known results by Micciancio (STOC, 2002). Our results also bring us closer to the limit where the problems are no longer known to be in NP /spl cap/ coNP. Our main tools are Gaussian measures on lattices and the high dimensional Fourier transform. We start by defining a new lattice parameter which determines the amount of Gaussian noise that one has to add to a lattice in order to get close to a uniform distribution, in addition to yielding quantitatively much stronger results, the use of this parameter allows us to simplify many of the complications in previous work. Our technical contributions are two-fold. First, we show tight connections between this new parameter and existing lattice parameters. One such important connection is between this parameter and the length of the shortest set of linearly independent vectors. Second, we prove that the distribution that one obtains after adding Gaussian noise to the lattice has the following interesting property: the distribution of the noise vector when conditioning on the final value behaves in many respects like the original Gaussian noise vector. In particular, its moments remain essentially unchanged.

Temporal Construal Effects on Abstract and Concrete Thinking: Consequences for Insight and Creative Cognition.

Abstract: Six studies investigate whether and how distant future time perspective facilitates abstract thinking and impedes concrete thinking by altering the level at which mental representations are construed. In Experiments 1-3, participants who envisioned their lives and imagined themselves engaging in a task 1 year later as opposed to the next day subsequently performed better on a series of insight tasks. In Experiments 4 and 5 a distal perspective was found to improve creative generation of abstract solutions. Moreover, Experiment 5 demonstrated a similar effect with temporal distance manipulated indirectly, by making participants imagine their lives in general a year from now versus tomorrow prior to performance. In Experiment 6, distant time perspective undermined rather than enhanced analytical problem solving.

Mesh-Independent Surface Interpolation

Abstract: Smooth interpolation of unstructured surface data is usually achieved by joining local patches, where each patch is an approximation (usually parametric) defined on a local reference domain. A basic mesh-independent projection strategy for general surface interpolation is proposed here. The projection is based upon the ’Moving-Least-Squares’ (MLS) approach, and the resulting surface is C ∞ smooth. The projection involves a first stage of defining a local reference domain and a second stage of constructing an MLS approximation with respect to the reference domain. The approach is presented for the general problem of approximating a (d − 1)-dimensional manifold in ℝ d , d ≥ 2. The approach is applicable for interpolating or smoothing curve and surface data, as demonstrated here by some graphical examples.

The genomic sequence of the accidental pathogen Legionella pneumophila.

Abstract: We present the genomic sequence of Legionella pneumophila, the bacterial agent of Legionnaires' disease, a potentially fatal pneumonia acquired from aerosolized contaminated fresh water The genome includes a 45-kilobase pair element that can exist in chromosomal and episomal forms, selective expansions of important gene families, genes for unexpected metabolic pathways, and previously unknown candidate virulence determinants We highlight the genes that may account for Legionella's ability to survive in protozoa, mammalian macrophages, and inhospitable environmental niches and that may define new therapeutic targets