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Showing papers by "Technion – Israel Institute of Technology published in 2007"


Proceedings Article
06 Jan 2007
TL;DR: This work proposes Explicit Semantic Analysis (ESA), a novel method that represents the meaning of texts in a high-dimensional space of concepts derived from Wikipedia that results in substantial improvements in correlation of computed relatedness scores with human judgments.
Abstract: Computing semantic relatedness of natural language texts requires access to vast amounts of common-sense and domain-specific world knowledge. We propose Explicit Semantic Analysis (ESA), a novel method that represents the meaning of texts in a high-dimensional space of concepts derived from Wikipedia. We use machine learning techniques to explicitly represent the meaning of any text as a weighted vector of Wikipedia-based concepts. Assessing the relatedness of texts in this space amounts to comparing the corresponding vectors using conventional metrics (e.g., cosine). Compared with the previous state of the art, using ESA results in substantial improvements in correlation of computed relatedness scores with human judgments: from r = 0.56 to 0.75 for individual words and from r = 0.60 to 0.72 for texts. Importantly, due to the use of natural concepts, the ESA model is easy to explain to human users.

2,285 citations


Book
12 Jun 2007
TL;DR: Random Fields and Geometry as discussed by the authors is a comprehensive survey of the general theory of Gaussian random fields with a focus on geometric problems arising in the study of random fields, including continuity and boundedness, entropy and majorizing measures, Borell and Slepian inequalities.
Abstract: * Recasts topics in random fields by following a completely new way of handling both geometry and probability * Significant exposition of the work of others in the field * Presentation is clear and pedagogical * Excellent reference work as well as excellent work for self study This monograph is devoted to a completely new approach to geometric problems arising in the study of random fields. The groundbreaking material in Part III, for which the background is carefully prepared in Parts I and II, is of both theoretical and practical importance, and striking in the way in which problems arising in geometry and probability are beautifully intertwined. The three parts to the monograph are quite distinct. Part I presents a user-friendly yet comprehensive background to the general theory of Gaussian random fields, treating classical topics such as continuity and boundedness, entropy and majorizing measures, Borell and Slepian inequalities. Part II gives a quick review of geometry, both integral and Riemannian, to provide the reader with the material needed for Part III, and to give some new results and new proofs of known results along the way. Topics such as Crofton formulae, curvature measures for stratified manifolds, critical point theory, and tube formulae are covered. In fact, this is the only concise, self-contained treatment of all of the above topics, which are necessary for the study of random fields. The new approach in Part III is devoted to the geometry of excursion sets of random fields and the related Euler characteristic approach to extremal probabilities. "Random Fields and Geometry" will be useful for probabilists and statisticians, and for theoretical and applied mathematicians who wish to learn about new relationships between geometry and probability. It will be helpful for graduate students in a classroom setting, or for self-study. Finally, this text will serve as a basic reference for all those interested in the companion volume of the applications of the theory. These applications, to appear in a forthcoming volume, will cover areas as widespread as brain imaging, physical oceanography, and astrophysics.

1,465 citations


Journal ArticleDOI
01 Mar 2007-Nature
TL;DR: The experimental observation of Anderson localization in a perturbed periodic potential is reported: the transverse localization of light caused by random fluctuations on a two-dimensional photonic lattice, demonstrating how ballistic transport becomes diffusive in the presence of disorder, and that crossover to Anderson localization occurs at a higher level of disorder.
Abstract: One of the most interesting phenomena in solid-state physics is Anderson localization, which predicts that an electron may become immobile when placed in a disordered lattice. The origin of localization is interference between multiple scatterings of the electron by random defects in the potential, altering the eigenmodes from being extended (Bloch waves) to exponentially localized. As a result, the material is transformed from a conductor to an insulator. Anderson's work dates back to 1958, yet strong localization has never been observed in atomic crystals, because localization occurs only if the potential (the periodic lattice and the fluctuations superimposed on it) is time-independent. However, in atomic crystals important deviations from the Anderson model always occur, because of thermally excited phonons and electron-electron interactions. Realizing that Anderson localization is a wave phenomenon relying on interference, these concepts were extended to optics. Indeed, both weak and strong localization effects were experimentally demonstrated, traditionally by studying the transmission properties of randomly distributed optical scatterers (typically suspensions or powders of dielectric materials). However, in these studies the potential was fully random, rather than being 'frozen' fluctuations on a periodic potential, as the Anderson model assumes. Here we report the experimental observation of Anderson localization in a perturbed periodic potential: the transverse localization of light caused by random fluctuations on a two-dimensional photonic lattice. We demonstrate how ballistic transport becomes diffusive in the presence of disorder, and that crossover to Anderson localization occurs at a higher level of disorder. Finally, we study how nonlinearities affect Anderson localization. As Anderson localization is a universal phenomenon, the ideas presented here could also be implemented in other systems (for example, matter waves), thereby making it feasible to explore experimentally long-sought fundamental concepts, and bringing up a variety of intriguing questions related to the interplay between disorder and nonlinearity.

1,368 citations


Journal ArticleDOI
TL;DR: Using chromatin immunoprecipitation analysis, this paper showed that genes methylated in cancer cells are specifically packaged with nucleosomes containing histone H3 trimethylated on Lys27.
Abstract: Many genes associated with CpG islands undergo de novo methylation in cancer. Studies have suggested that the pattern of this modification may be partially determined by an instructive mechanism that recognizes specifically marked regions of the genome. Using chromatin immunoprecipitation analysis, here we show that genes methylated in cancer cells are specifically packaged with nucleosomes containing histone H3 trimethylated on Lys27. This chromatin mark is established on these unmethylated CpG island genes early in development and then maintained in differentiated cell types by the presence of an EZH2-containing Polycomb complex. In cancer cells, as opposed to normal cells, the presence of this complex brings about the recruitment of DNA methyl transferases, leading to de novo methylation. These results suggest that tumor-specific targeting of de novo methylation is pre-programmed by an established epigenetic system that normally has a role in marking embryonic genes for repression.

1,153 citations


Journal ArticleDOI
TL;DR: Research on work motivation, or the factors that energize, direct, and sustain effort across cultures, is reviewed, showing that developmentally, cross-cultural research in OB is coming of age and critical challenges for future research are highlighted.
Abstract: This article reviews research on cross-cultural organizational behavior (OB). After a brief review of the history of cross-cultural OB, we review research on work motivation, or the factors that energize, direct, and sustain effort across cultures. We next consider the relationship between the individual and the organization, and review research on culture and organizational commitment, psychological contracts, justice, citizenship behavior, and person-environment fit. Thereafter, we consider how individuals manage their interdependence in organizations, and review research on culture and negotiation and disputing, teams, and leadership, followed by research on managing across borders and expatriation. The review shows that developmentally, cross-cultural research in OB is coming of age. Yet we also highlight critical challenges for future research, including moving beyond values to explain cultural differences, attending to levels of analysis issues, incorporating social and organizational contex...

1,073 citations


Journal ArticleDOI
Oluseun Adewumi1, Behrouz Aflatoonian2, Lars Ährlund-Richter3, Michal Amit4, Peter W. Andrews2, Gemma Beighton5, Paul Bello6, Nissim Benvenisty7, Lorraine S. Berry1, Simon Bevan, Barak Blum7, Justin Brooking8, Kevin G. Chen9, Andre Bh Choo, Gary A. Churchill, Marie Corbel10, Ivan Damjanov11, John S Draper12, Petr Dvorak13, Petr Dvorak14, Katarina Emanuelsson, Roland A. Fleck1, Angela Ford2, Karin Astrid Maria Gertow3, Karin Astrid Maria Gertow6, Marina Gertsenstein12, Paul J. Gokhale2, Rebecca S. Hamilton9, Alex Hampl13, Alex Hampl14, Lyn Healy1, Outi Hovatta3, Johan Hyllner, Marta P. Imreh3, Marta P. Imreh15, Joseph Itskovitz-Eldor4, Jamie P. Jackson2, Jackie Johnson6, Mark Jones2, Kehkooi Kee16, Benjamin L. King, Barbara B. Knowles, Majlinda Lako17, Franck Lebrin18, Barbara S. Mallon9, Daisy Manning19, Yoav Mayshar7, Ronald D.G. McKay9, Anna E. Michalska6, Milla Mikkola20, Masha Mileikovsky12, Stephen L. Minger21, Harry Moore2, Christine L. Mummery, Andras Nagy, Norio Nakatsuji22, Carmel M. O’Brien6, Steve Oh, Cia Olsson20, Timo Otonkoski20, Kye-Yoon Park9, Robert Passier, Hema Patel1, Minal Patel21, Roger A. Pedersen10, Martin F. Pera23, Marian S Piekarczyk19, Renee A. Reijo Pera16, Benjamin Reubinoff, Allan J. Robins, Janet Rossant12, Peter J. Rugg-Gunn12, Peter J. Rugg-Gunn10, Thomas C Schulz, Henrik Semb, Eric S Sherrer, Henrike Siemen16, Glyn Stacey1, Miodrag Stojkovic17, Hirofumi Suemori22, Jin P. Szatkiewicz, Tikva Turetsky, Timo Tuuri20, Steineke van den Brink, Kristina Vintersten12, Sanna Vuoristo20, Dorien Ward, Thomas A Weaver, Lesley Young1, Weidong Zhang 
TL;DR: The International Stem Cell Initiative characterized 59 human embryonic stem cell lines from 17 laboratories worldwide and found that despite diverse genotypes and different techniques used for derivation and maintenance, all lines exhibited similar expression patterns for several markers ofhuman embryonic stem cells.
Abstract: The International Stem Cell Initiative characterized 59 human embryonic stem cell lines from 17 laboratories worldwide. Despite diverse genotypes and different techniques used for derivation and maintenance, all lines exhibited similar expression patterns for several markers of human embryonic stem cells. They expressed the glycolipid antigens SSEA3 and SSEA4, the keratan sulfate antigens TRA-1-60, TRA-1-81, GCTM2 and GCT343, and the protein antigens CD9, Thy1 (also known as CD90), tissue- nonspecific alkaline phosphatase and class 1 HLA, as well as the strongly developmentally regulated genes NANOG, POU5F1 (formerly known as OCT4), TDGF1, DNMT3B, GABRB3 and GDF3. Nevertheless, the lines were not identical: differences in expression of several lineage markers were evident, and several imprinted genes showed generally similar allele-specific expression patterns, but some gene-dependent variation was observed. Also, some female lines expressed readily detectable levels of XIST whereas others did not. No significant contamination of the lines with mycoplasma, bacteria or cytopathic viruses was detected.

1,064 citations


Journal ArticleDOI
TL;DR: This paper considers the optimization of compressed sensing projections, and targets an average measure of the mutual coherence of the effective dictionary, and shows that this leads to better CS reconstruction performance.
Abstract: Compressed sensing (CS) offers a joint compression and sensing processes, based on the existence of a sparse representation of the treated signal and a set of projected measurements. Work on CS thus far typically assumes that the projections are drawn at random. In this paper, we consider the optimization of these projections. Since such a direct optimization is prohibitive, we target an average measure of the mutual coherence of the effective dictionary, and demonstrate that this leads to better CS reconstruction performance. Both the basis pursuit (BP) and the orthogonal matching pursuit (OMP) are shown to benefit from the newly designed projections, with a reduction of the error rate by a factor of 10 and beyond.

834 citations


Journal ArticleDOI
TL;DR: This paper describes two prior classes, analysis-based and synthesis-based, and shows that although when reducing to the complete and under-complete formulations the two become equivalent, in their more interesting overcomplete formulation the two types depart.
Abstract: The concept of prior probability for signals plays a key role in the successful solution of many inverse problems. Much of the literature on this topic can be divided between analysis-based and synthesis-based priors. Analysis-based priors assign probability to a signal through various forward measurements of it, while synthesis-based priors seek a reconstruction of the signal as a combination of atom signals. The algebraic similarity between the two suggests that they could be strongly related; however, in the absence of a detailed study, contradicting approaches have emerged. While the computationally intensive synthesis approach is receiving ever-increasing attention and is notably preferred, other works hypothesize that the two might actually be much closer, going as far as to suggest that one can approximate the other. In this paper we describe the two prior classes in detail, focusing on the distinction between them. We show that although in the simpler complete and undercomplete formulations the two approaches are equivalent, in their overcomplete formulation they depart. Focusing on the l1 case, we present a novel approach for comparing the two types of priors based on high-dimensional polytopal geometry. We arrive at a series of theoretical and numerical results establishing the existence of an unbridgeable gap between the two.

777 citations


Journal ArticleDOI
TL;DR: In this article, the authors reveal the multifaceted contribution of alliance portfolios to firms' market performance and highlight the trade-offs that alliance portfolios impose on firms that seek to manage and leverage their alliances.
Abstract: This study reveals the multifaceted contribution of alliance portfolios to firms' market performance. Extending prior research that has stressed the value-creation effect of network resources, it uncovers how prominent partners may undermine a firm's capacity to appropriate value from its alliance portfolio. Analysis of a comprehensive panel dataset of 367 software firms and their 20,779 alliances suggests that the contribution of network resources to value creation varies with the complementarity of those resources. Furthermore, the relative bargaining power of partners in the alliance portfolio constrains the firm's appropriation capacity, especially when many of these partners compete in the focal firm's industry. In turn, the firm's market performance improves with the intensity of competition among partners in its alliance portfolio. These findings advance network research by highlighting the trade-offs that alliance portfolios impose on firms that seek to manage and leverage their alliances. Copyright © 2007 John Wiley & Sons, Ltd.

743 citations


Journal ArticleDOI
01 Feb 2007-Blood
TL;DR: It is concluded from a large, unselected series with mature follow-up that most adults with recurring ALL cannot be rescued using currently available therapies and prevention of recurrence is the best strategy for long-term survival in this disease.

710 citations


Journal ArticleDOI
TL;DR: The periphyton treatment technique is applicable to extensive systems, and the proteinaceous bio-flocs technology can be used in extensive as well as in intensive systems, which provide an inexpensive feed source and a higher efficiency of nutrient conversion of feed.

Journal ArticleDOI
TL;DR: The implementation of this framework in a software application, termed DRIM (discovery of rank imbalanced motifs), which identifies sequence motifs in lists of ranked DNA sequences, is demonstrated, demonstrating that the statistical framework embodied in the DRIM software tool is highly effective for identifying regulatory sequence elements in a variety of applications.
Abstract: Computational methods for discovery of sequence elements that are enriched in a target set compared with a background set are fundamental in molecular biology research. One example is the discovery of transcription factor binding motifs that are inferred from ChIP–chip (chromatin immuno-precipitation on a microarray) measurements. Several major challenges in sequence motif discovery still require consideration: (i) the need for a principled approach to partitioning the data into target and background sets; (ii) the lack of rigorous models and of an exact p-value for measuring motif enrichment; (iii) the need for an appropriate framework for accounting for motif multiplicity; (iv) the tendency, in many of the existing methods, to report presumably significant motifs even when applied to randomly generated data. In this paper we present a statistical framework for discovering enriched sequence elements in ranked lists that resolves these four issues. We demonstrate the implementation of this framework in a software application, termed DRIM (discovery of rank imbalanced motifs), which identifies sequence motifs in lists of ranked DNA sequences. We applied DRIM to ChIP–chip and CpG methylation data and obtained the following results. (i) Identification of 50 novel putative transcription factor (TF) binding sites in yeast ChIP–chip data. The biological function of some of them was further investigated to gain new insights on transcription regulation networks in yeast. For example, our discoveries enable the elucidation of the network of the TF ARO80. Another finding concerns a systematic TF binding enhancement to sequences containing CA repeats. (ii) Discovery of novel motifs in human cancer CpG methylation data. Remarkably, most of these motifs are similar to DNA sequence elements bound by the Polycomb complex that promotes histone methylation. Our findings thus support a model in which histone methylation and CpG methylation are mechanistically linked. Overall, we demonstrate that the statistical framework embodied in the DRIM software tool is highly effective for identifying regulatory sequence elements in a variety of applications ranging from expression and ChIP–chip to CpG methylation data. DRIM is publicly available at http://bioinfo.cs.technion.ac.il/drim.

Book ChapterDOI
TL;DR: In this article, the mechanism and electrohydrodynamic modeling of the instabilities and related processes resulting in electrospinning of nanofibers were discussed, and a unique electrostatic field-assisted assembly technique was developed with the aim to position and align individual conducting and light-emitting nanofiber in arrays and ropes.
Abstract: A straightforward, cheap and unique method to produce novel fibers with a diameter in the range of 100 nm and even less is related to electrospinning. For this goal, polymer solutions, liquid crystals, suspensions of solid particles and emulsions, are electrospun in the electric field of about 1 kV/cm. The electric force results in an electrically charged jet of polymer solution flowing out from a pendant or sessile droplet. After the jet flows away from the droplet in a nearly straight line, it bends into a complex path and other changes in shape occur, during which electrical forces stretch and thin it by very large ratios. After the solvent evaporates, birefringent nanofibers are left. Nanofibers of ordinary, conducting and photosensitive polymers were electrospun. The present review deals with the mechanism and electrohydrodynamic modeling of the instabilities and related processes resulting in electrospinning of nanofibers. Also some applications are discussed. In particular, a unique electrostatic field-assisted assembly technique was developed with the aim to position and align individual conducting and light-emitting nanofibers in arrays and ropes. These structures are of potential interest in the development of novel polymer-based light-emitting diodes (LED), diodes, transistors, photonic crystals and flexible photocells. Some other applications discussed include micro-aerodynamic decelerators and tiny flying objects based on permeable nanofiber mats (smart dust), nanofiber-based filters, protective clothing, biomedical applications including wound dressings, drug delivery systems based on nanotubes, the design of solar sails, light sails and mirrors for use in space, the application of pesticides to plants, structural elements in artificial organs, reinforced composites, as well as nanofibers reinforced by carbon nanotubes.

Journal ArticleDOI
TL;DR: Transplantation of hESC-CMs after extensive myocardial infarction in rats results in the formation of stable cardiomyocyte grafts, attenuation of the remodeling process, and functional benefit.

Journal ArticleDOI
TL;DR: This is the first report of the construction of 3D vascularized human cardiac tissue that may have unique applications for studies of cardiac development, function, and tissue replacement therapy.
Abstract: Transplantation of a tissue-engineered heart muscle represents a novel experimental therapeutic paradigm for myocardial diseases. However, this strategy has been hampered by the lack of sources for human cardiomyocytes and by the scarce vasculature in the ischemic area limiting the engraftment and survival of the transplanted muscle. Beyond the necessity of endothelial capillaries for the delivery of oxygen and nutrients to the grafted muscle tissue, interactions between endothelial and cardiomyocyte cells may also play a key role in promoting cell survival and proliferation. In the present study, we describe the formation of synchronously contracting engineered human cardiac tissue derived from human embryonic stem cells containing endothelial vessel networks. The 3D muscle consisted of cardiomyocytes, endothelial cells (ECs), and embryonic fibroblasts (EmFs). The formed vessels were further stabilized by the presence of mural cells originating from the EmFs. The presence of EmFs decreased EC death and increased EC proliferation. Moreover, the presence of endothelial capillaries augmented cardiomyocyte proliferation and did not hamper cardiomyocyte orientation and alignment. Immunostaining, ultrastructural analysis (using transmission electron microscopy), RT-PCR, pharmacological, and confocal laser calcium imaging studies demonstrated the presence of cardiac-specific molecular, ultrastructural, and functional properties of the generated tissue constructs with synchronous activity mediated by action potential propagation through gap junctions. In summary, this is the first report of the construction of 3D vascularized human cardiac tissue that may have unique applications for studies of cardiac development, function, and tissue replacement therapy.

Journal ArticleDOI
TL;DR: This preliminary evaluation was based on the assumption that fish harvesting is the only mechanism affecting bio-flocs mass, neglecting biodegradation and production of flocs, and constituted almost 50% of conventional feed in the specific case studied.

Journal ArticleDOI
TL;DR: The paper presents a heuristic overview of the pH dependent kinetics of aqueous ferrous oxidation by O(2(aq)) which it is believed will be useful to professionals at both research and technical levels.

Journal ArticleDOI
TL;DR: In this article, a longitudinal case-study aimed at examining whether purposely teaching for the promotion of higher order thinking skills enhances students' critical thinking (CT), within the framework of science education was conducted.
Abstract: This longitudinal case-study aimed at examining whether purposely teaching for the promotion of higher order thinking skills enhances students’ critical thinking (CT), within the framework of science education. Within a pre-, post-, and post–post experimental design, high school students, were divided into three research groups. The experimental group (n = 57) consisted of science students who were exposed to teaching strategies designed for enhancing higher order thinking skills. Two other groups: science (n = 41) and non-science majors (n = 79), were taught traditionally, and acted as control. By using critical thinking assessment instruments, we have found that the experimental group showed a statistically significant improvement on critical thinking skills components and disposition towards critical thinking subscales, such as truth-seeking, open-mindedness, self-confidence, and maturity, compared with the control groups. Our findings suggest that if teachers purposely and persistently practice higher order thinking strategies for example, dealing in class with real-world problems, encouraging open-ended class discussions, and fostering inquiry-oriented experiments, there is a good chance for a consequent development of critical thinking capabilities.

Journal ArticleDOI
TL;DR: In this article, rest-frame ultraviolet spectrophotometric monitoring of a sample of six quasars at redshifts z = 2.2-3.2, with luminosities of Lopt ~ 1046.4-1047.6 ergs s-1, was carried out at the Hobby-Eberly Telescope.
Abstract: Reverberation mapping of nearby active galactic nuclei (AGNs) has led to estimates of broad-line region (BLR) sizes and central object masses for some 37 objects to date. However, successful reverberation mapping has yet to be performed for quasars of either high luminosity (above Lopt ~ 1046 ergs s-1) or high redshift (z 0.3). Over the past 6 years, we have carried out, at the Hobby-Eberly Telescope, rest-frame ultraviolet spectrophotometric monitoring of a sample of six quasars at redshifts z = 2.2-3.2, with luminosities of Lopt ~ 1046.4-1047.6 ergs s-1, an order of magnitude greater than those of previously mapped quasars. The six quasars, together with an additional five having similar redshift and luminosity properties, were monitored photometrically at the Wise Observatory during the past decade. All 11 quasars monitored show significant continuum variations of order 10%-70%. This is about a factor of 2 smaller variability than for lower luminosity quasars monitored over the same rest-frame period. In the six objects that have been spectrophotometrically monitored, significant variability is detected in the C IV ?1550 broad emission line. In several cases the variations track the continuum variations in the same quasar, with amplitudes comparable to, or even greater than, those of the corresponding continua. In contrast, no significant Ly? variability is detected in any of the four objects in which it was observed. Thus, UV lines may have different variability trends in high-luminosity and low-luminosity AGNs. For one quasar, S5 0836+71 at z = 2.172, we measure a tentative delay of 595 days between C IV and UV continuum variations, corresponding to a rest-frame delay of 188 days and a central black hole mass of 2.6 ? 109 M?.

Journal ArticleDOI
TL;DR: In this paper, the authors harnessed casein micelles for nano-encapsulation and stabilization of hydrophobic nutraceutical substances for enrichment of non-fat or low-fat food products.

Journal ArticleDOI
TL;DR: It is proposed that interstitial (dermal) DCs preferentially activate humoral immunity, whereas Langerhans cells preferential induce cellular immunity.
Abstract: The dendritic cell (DC) system of antigen-presenting cells controls immunity and tolerance. DCs initiate and regulate immune responses in a manner that depends on signals they receive from microbes and their cellular environment. They allow the immune system to make qualitatively distinct responses against different microbial infections. DCs are composed of subsets that express different microbial receptors and express different surface molecules and cytokines. Our studies lead us to propose that interstitial (dermal) DCs preferentially activate humoral immunity, whereas Langerhans cells preferentially induce cellular immunity. Alterations of the DC system result in diseases such as autoimmunity, allergy, and cancer. Conversely, DCs can be exploited for vaccination, and novel vaccines that directly target DCs in vivo are being designed.

Journal ArticleDOI
TL;DR: It is suggested that basal dendrites, despite their proximity to the site of action potential initiation, do not form a single basal-somatic region but rather should be considered as a separate integrative compartment favoring two integration modes: subthreshold, location-independent summation versus local amplification of incoming spatiotemporally clustered information.
Abstract: Basal dendrites receive the majority of synapses that contact neocortical pyramidal neurons, yet our knowledge of synaptic processing in these dendrites has been hampered by their inaccessibility for electrical recordings. A new approach to patch-clamp recordings enabled us to characterize the integrative properties of these cells. Despite the short physical length of rat basal dendrites, synaptic inputs were electrotonically remote from the soma (>30-fold excitatory postsynaptic potential (EPSP) attenuation) and back-propagating action potentials were significantly attenuated. Unitary EPSPs were location dependent, reaching large amplitudes distally (>8 mV), yet their somatic contribution was relatively location independent. Basal dendrites support sodium and NMDA spikes, but not calcium spikes, for 75% of their length. This suggests that basal dendrites, despite their proximity to the site of action potential initiation, do not form a single basal-somatic region but rather should be considered as a separate integrative compartment favoring two integration modes: subthreshold, location-independent summation versus local amplification of incoming spatiotemporally clustered information.

Journal ArticleDOI
21 Jun 2007-Nature
TL;DR: The results indicate that murine and human tumours experience common biological processes driven by orthologous genetic events in their malignant evolution.
Abstract: Highly rearranged and mutated cancer genomes present major challenges in the identification of pathogenetic events driving the neoplastic transformation process. Here we engineered lymphoma-prone mice with chromosomal instability to assess the usefulness of mouse models in cancer gene discovery and the extent of cross-species overlap in cancer-associated copy number aberrations. Along with targeted re-sequencing, our comparative oncogenomic studies identified FBXW7 and PTEN to be commonly deleted both in murine lymphomas and in human T-cell acute lymphoblastic leukaemia/lymphoma (T-ALL). The murine cancers acquire widespread recurrent amplifications and deletions targeting loci syntenic to those not only in human T-ALL but also in diverse human haematopoietic, mesenchymal and epithelial tumours. These results indicate that murine and human tumours experience common biological processes driven by orthologous genetic events in their malignant evolution. The highly concordant nature of genomic events encourages the use of genomically unstable murine cancer models in the discovery of biological driver events in the human oncogenome.

Journal ArticleDOI
TL;DR: The main obstacles for large scale application, beside the high first cost, are the lack of practical experience and acquaintance among architects, builders and planners with the design, control and operation of these systems as mentioned in this paper.
Abstract: Summer air conditioning represents a growing market in buildings worldwide, with a particularly significant growth rate observed in European commercial and residential buildings. Heat-driven cooling technologies are available, which can be used in combination with solar thermal collectors to alleviate the burden caused by air conditioning on the electric utilities and the environment. Solar air conditioning has progressed considerably over the past years as a result of efforts toward environmental protection and new developments in components and systems, and significant experience has been gained from demonstration projects. The main obstacles for large scale application, beside the high first cost, are the lack of practical experience and acquaintance among architects, builders and planners with the design, control and operation of these systems. This paper describes the main results of the EU project SACE (Solar Air Conditioning in Europe), aimed to assess the state-of-the-art, future needs and overall prospects of solar cooling in Europe. A group of researchers from five countries has surveyed and analyzed over 50 solar-powered cooling projects in different climatic zones. The paper presents a short overview on the state-of-the-art and potential of solar-assisted cooling and air conditioning technologies. The results of the study, including a database of the surveyed projects, an evaluation of these projects on a uniform basis, an economic analysis tool, user guidelines and a multimedia tool—are presented. The potential energy savings and limitations of solar thermal air conditioning in comparison to conventional technologies are illustrated and discussed.

Journal ArticleDOI
TL;DR: It is shown that the negative of the OCE naturally provides a wide family of risk measures that fits the axiomatic formalism of convex risk measures.
Abstract: The optimized certainty equivalent (OCE) is a decision theoretic criterion based on a utility function, that was first introduced by the authors in 1986. This paper re-examines this fundamental concept, studies and extends its main properties, and puts it in perspective to recent concepts of risk measures. We show that the negative of the OCE naturally provides a wide family of risk measures that fits the axiomatic formalism of convex risk measures. Duality theory is used to reveal the link between the OCE and the ϕ-divergence functional (a generalization of relative entropy), and allows for deriving various variational formulas for risk measures. Within this interpretation of the OCE, we prove that several risk measures recently analyzed and proposed in the literature (e.g., conditional value of risk, bounded shortfall risk) can be derived as special cases of the OCE by using particular utility functions. We further study the relations between the OCE and other certainty equivalents, providing general conditions under which these can be viewed as coherent/convex risk measures. Throughout the paper several examples illustrate the flexibility and adequacy of the OCE for building risk measures.

Journal ArticleDOI
04 Oct 2007-Nature
TL;DR: In this paper, a trapped-atom interferometer with continuous readout was used to measure the chemical potential-current relation of the Bose-Einstein condensate Josephson junction.
Abstract: The alternating- and direct-current (a.c. and d.c.) Josephson effects were first discovered in a system of two superconductors, the macroscopic wavefunctions of which are weakly coupled via a tunnelling barrier. In the a.c. Josephson effect, a constant chemical potential difference (voltage) is applied, which causes an oscillating current to flow through the barrier. Because the frequency is proportional to the chemical potential difference only, the a.c. Josephson effect serves as a voltage standard. In the d.c. Josephson effect, a small constant current is applied, resulting in a constant supercurrent flowing through the barrier. In a sense, the particles do not 'feel' the presence of the tall tunnelling barrier, and flow freely through it with no driving potential. Bose-Einstein condensates should also support Josephson effects; however, while plasma oscillations have been seen in a single Bose-Einstein condensate Josephson junction, the a.c. Josephson effect remains elusive. Here we observe the a.c. and d.c. Josephson effects in a single Bose-Einstein condensate Josephson junction. The d.c. Josephson effect has been observed previously only in superconducting systems; in our study, it is evident when we measure the chemical potential-current relation of the Bose-Einstein condensate Josephson junction. Our system constitutes a trapped-atom interferometer with continuous readout, which operates on the basis of the a.c. Josephson effect. In addition, the measured chemical potential-current relation shows that the device is suitable for use as an analogue of the superconducting quantum interference device, which would sense rotation.

Journal ArticleDOI
TL;DR: This manuscript documents the development of a validated index for capsule endoscopy findings and states that this index is likely to be applicable to small bowel mucosal inflammatory change.
Abstract: Summary Background Capsule endoscopy can identify small bowel mucosal inflammatory change. However, there has been no validated index for capsule endoscopy findings. This manuscript documents the development of such an index. Aim To develop a capsule endoscopy scoring index for small bowel mucosal inflammatory change. Methods The index was created in four separate steps. First, parameters and descriptors of inflammatory change were identified. Secondly, blinded readers prospectively graded the presence or absence of each parameter on de-identified videos and graded a perceived global assessment of overall severity. Thirdly, the individual parameters and descriptors were ranked in order of severity. Fourthly, values for each parameter were created using the descent gradient methodology. The premise was to assure that the final numerical score reflected the global assessment and that the global assessment agreed with the ranking of finding severity. Results were compiled for the three categories: no or clinically insignificant change, mild change, and moderate or severe change. Thresholds were determined. Results The final index includes three parameters: villous oedema, ulcer and stenosis. A score <135 is designated normal or clinically insignificant mucosal inflammatory change, a score between 135 and 790 is mild, and a score ≥790 is moderate to severe. Conclusion This capsule endoscopy score provides a common language to quantify small bowel inflammatory changes.

Book ChapterDOI
08 Oct 2007
TL;DR: A (1 - 1/e)-competitive (optimal) algorithm is designed for the online ad-auctions problem, which is based on a clean primal-dual approach, matching the competitive factor obtained in Mehta et al.
Abstract: We study the online ad-auctions problem introduced by Mehta et al. [15]. We design a (1 - 1/e)-competitive (optimal) algorithm for the problem, which is based on a clean primal-dual approach, matching the competitive factor obtained in [15]. Our basic algorithm along with its analysis are very simple. Our results are based on a unified approach developed earlier for the design of online algorithms [7,8]. In particular, the analysis uses weak duality rather than a tailor made (i.e., problem specific) potential function. We show that this approach is useful for analyzing other classical online algorithms such as ski rental and the TCP-acknowledgement problem. We are confident that the primal-dual method will prove useful in other online scenarios as well. The primal-dual approach enables us to extend our basic ad-auctions algorithm in a straight forward manner to scenarios in which additional information is available, yielding improved worst case competitive factors. In particular, a scenario in which additional stochastic information is available to the algorithm, a scenario in which the number of interested buyers in each product is bounded by some small number d, and a general risk management framework.

Journal ArticleDOI
TL;DR: This survey reveals many examples where corroles were used as the key components in catalysis, sensing of gaseous molecules and medicine-oriented research, and the focus in all these cases was on the special features of corroles: stabilization of high valent transition metal ions, unique photophysical properties, large NH acidity, facile synthetic manipulation and distinct catalytic properties.

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TL;DR: The results showed that the antioxidant activity in aril juice correlated significantly to the total polyphenol and anthocyanin contents, however, the homogenates prepared from the whole fruit exhibited an approximately 20-fold higher antioxidant activity than the level found in the aril Juice.
Abstract: Pomegranate juice is well known for its health beneficial compounds, which can be attributed to its high level of antioxidant activity and total polyphenol content. Our objective was to study the relationships between antioxidant activity, total polyphenol content, total anthocyanins content, and the levels of four major hydrolyzable tannins in four different juices/homogenates prepared from different sections of the fruit. To this end, 29 different accessions were tested. The results showed that the antioxidant activity in aril juice correlated significantly to the total polyphenol and anthocyanin contents. However, the homogenates prepared from the whole fruit exhibited an approximately 20-fold higher antioxidant activity than the level found in the aril juice. Unlike the arils, the antioxidant level in the homogenates correlated significantly to the content of the four hydrolyzable tannins in which punicalagin is predominant, while no correlation was found to the level of anthocyanins.