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SINR Diagrams: Towards Algorithmically Usable SINR Models of Wireless Networks. (arXiv:0811.3284v1 [cs.NI]) - The rules governing the availability and quality of connections in a wireless network are described by physical models such as the signal-to-interference & noise ratio (SINR) model. For a collection of simultaneously transmitting stations in the plane, it is possible to identify a reception zone for each station, consisting of the points where its transmission is received correctly. The resulting SINR diagram partitions the plane into a reception zone per station and the remaining plane where no station can be heard. SINR diagrams appear to be fundamental to understanding the behavior of wireless networks, and may play a key role in the development of suitable algorithms for such networks, analogous perhaps to the role played by Voronoi diagrams in the study of proximity queries and related issues in computational geometry. So far, however, the properties of SINR diagrams have not been studied systematically, and most algorithmic studies in wireless networking rely on si...
Feed Source: arxiv.org

Faster Retrieval with a Two-Pass Dynamic-Time-Warping Lower Bound. (arXiv:0811.3301v1 [cs.DB]) - The Dynamic Time Warping (DTW) is a popular similarity measure between time series. The DTW fails to satisfy the triangle inequality and its computation requires quadratic time. Hence, to find closest neighbors quickly, we use bounding techniques. We can avoid most DTW computations with an inexpensive lower bound (LB Keogh). We compare LB Keogh with a tighter lower bound (LB Improved). We find that LB Improved-based search is faster. As an example, our approach is 2-3 times faster over random-walk and shape time series. ...
Feed Source: arxiv.org

chi2TeX Semi-automatic translation from chiwriter to LaTeX. (arXiv:0811.3328v1 [cs.SE]) - Semi-automatic translation of math-filled book from obsolete ChiWriter format to LaTeX. Is it possible? Idea of criterion whether to use automatic or hand mode for translation. Illustrations. ...
Feed Source: arxiv.org

Belief functions on lattices. (arXiv:0811.3373v1 [cs.DM]) - We extend the notion of belief function to the case where the underlying structure is no more the Boolean lattice of subsets of some universal set, but any lattice, which we will endow with a minimal set of properties according to our needs. We show that all classical constructions and definitions (e.g., mass allocation, commonality function, plausibility functions, necessity measures with nested focal elements, possibility distributions, Dempster rule of combination, decomposition w.r.t. simple support functions, etc.) remain valid in this general setting. Moreover, our proof of decomposition of belief functions into simple support functions is much simpler and general than the original one by Shafer. ...
Feed Source: arxiv.org

Broadcasting in Prefix Space: P2P Data Dissemination with Predictable Performance. (arXiv:0811.3387v1 [cs.NI]) - A broadcast mode may augment peer-to-peer overlay networks with an efficient, scalable data replication function, but may also give rise to a virtual link layer in VPN-type solutions. We introduce a simple broadcasting mechanism that operates in the prefix space of distributed hash tables without signaling. This paper concentrates on the performance analysis of the prefix flooding scheme. Starting from simple models of recursive $k$-ary trees, we analytically derive distributions of hop counts and the replication load. Extensive simulation results are presented further on, based on an implementation within the OverSim framework. Comparisons are drawn to Scribe, taken as a general reference model for group communication according to the shared, rendezvous-point-centered distribution paradigm. The prefix flooding scheme thereby confirmed its widely predictable performance and consistently outperformed Scribe in all metrics. Reverse path selection in overlays is identified as a major c...
Feed Source: arxiv.org

Elasticity and Viral Conductance: Unveiling Robustness in Complex Networks through Topological Characteristics. (arXiv:0811.3272v1 [cs.NI]) - The capacity to measure robustness in complex networks defines the resolve of a network to remain unaffected in the advent of classical component failures and at the onset of cryptic malicious attacks. In an effort to measure robustness, selection and definition of network metrics for robustness must be performed taking into account the specific network problem we want to prevent. To date, robustness metrics are deficient and unfortunately the following dilemmas exist: accurate models necessitate complex analysis while conversely, simple models are unable to capture our definition of robustness. In this paper, we propose two new metrics respectively for robustness with respect to massive random and targeted failures, and for virus spread. We test our metrics in multiple topologies, outlining which topologies show high levels of robustness and consequently which topological characteristics are typical of robust networks. Some initial results on criteria to design robust topologies wi...
Feed Source: arxiv.org

An experimental analysis of Lemke-Howson algorithm. (arXiv:0811.3247v1 [cs.DS]) - We present an experimental investigation of the performance of the Lemke-Howson algorithm, which is the most widely used algorithm for the computation of a Nash equilibrium for bimatrix games. Lemke-Howson algorithm is based upon a simple pivoting strategy, which corresponds to following a path whose endpoint is a Nash equilibrium. We analyze both the basic Lemke-Howson algorithm and a heuristic modification of it, which we designed to cope with the effects of a 'bad' initial choice of the pivot. Our experimental findings show that, on uniformly random games, the heuristics achieves a linear running time, while the basic Lemke-Howson algorithm runs in time roughly proportional to a polynomial of degree seven. To conduct the experiments, we have developed our own implementation of Lemke-Howson algorithm, which turns out to be significantly faster than state-of-the-art software. This allowed us to run the algorithm on a much larger set of data, and on instances of much larger size, co...
Feed Source: arxiv.org

A Rational Deconstruction of Landin's SECD Machine with the J Operator. (arXiv:0811.3231v1 [cs.PL]) - Landin's SECD machine was the first abstract machine for applicative expressions, i.e., functional programs. Landin's J operator was the first control operator for functional languages, and was specified by an extension of the SECD machine. We present a family of evaluation functions corresponding to this extension of the SECD machine, using a series of elementary transformations (transformation into continu-ation-passing style (CPS) and defunctionalization, chiefly) and their left inverses (transformation into direct style and refunctionalization). To this end, we modernize the SECD machine into a bisimilar one that operates in lockstep with the original one but that (1) does not use a data stack and (2) uses the caller-save rather than the callee-save convention for environments. We also identify that the dump component of the SECD machine is managed in a callee-save way. The caller-save counterpart of the modernized SECD machine precisely corresponds to Thielecke's double-barrell...
Feed Source: arxiv.org

Linear Time Approximation Schemes for the Gale-Berlekamp Game and Related Minimization Problems. (arXiv:0811.3244v1 [cs.DS]) - We design a linear time approximation scheme for the Gale-Berlekamp Switching Game and generalize it to a wider class of dense fragile minimization problems including the Nearest Codeword Problem (NCP) and Unique Games Problem. Further applications include, among other things, finding a constrained form of matrix rigidity and maximum likelihood decoding of an error correcting code. As another application of our method we give the first linear time approximation schemes for correlation clustering with a fixed number of clusters and its hierarchical generalization. Our results depend on a new technique for dealing with small objective function values of optimization problems and could be of independent interest. ...
Feed Source: arxiv.org

A Cloning Pushout Approach to Term-Graph Transformation. (arXiv:0811.3400v1 [cs.LO]) - We address the problem of cyclic termgraph rewriting. We propose a new framework where rewrite rules are tuples of the form $(L,R,\tau,\sigma)$ such that $L$ and $R$ are termgraphs representing the left-hand and the right-hand sides of the rule, $\tau$ is a mapping from the nodes of $L$ to those of $R$ and $\sigma$ is a partial function from nodes of $R$ to nodes of $L$. $\tau$ describes how incident edges of the nodes in $L$ are connected in $R$. $\tau$ is not required to be a graph morphism as in classical algebraic approaches of graph transformation. The role of $\sigma$ is to indicate the parts of $L$ to be cloned (copied). Furthermore, we introduce a new notion of \emph{cloning pushout} and define rewrite steps as cloning pushouts in a given category. Among the features of the proposed rewrite systems, we quote the ability to perform local and global redirection of pointers, addition and deletion of nodes as well as cloning and collapsing substructures. ...
Feed Source: arxiv.org

Sequential, Parallel, Online, and Distributed Covering. (arXiv:0807.0644v2 [cs.DS] UPDATED) - The paper presents new d-approximation algorithms for covering problems, where d is the maximum number of variables on which any constraint depends (generalizing 2-approximation algorithms for Vertex Cover). Specific results include: A d-approximation algorithm for a generalization of Covering Mixed Integer Linear Programs. This runs in nearly linear time. (Generalizes ellipsoid-based results by Carr et al). For d=2, a parallel implementation in RNC and a distributed implementation taking O(log n) rounds. (For the special case of Vertex Cover, this gives the first 2-approximation in RNC, and the first distributed 2-approximation taking sub-linear rounds.) For general d, a d-approximation algorithm taking O(log^2 n) rounds. Online d-competitive algorithms for the setting where constraints are revealed in an online fashion (generalizing Ski-Rental and several caching problems and algorithms). A quadratic-time implementation for a 2-stage version of the ...
Feed Source: arxiv.org

The Peculiar Phase Structure of Random Graph Bisection. (arXiv:0808.1549v2 [cond-mat.stat-mech] UPDATED) - The mincut graph bisection problem involves partitioning the n vertices of a graph into disjoint subsets, each containing exactly n/2 vertices, while minimizing the number of "cut" edges with an endpoint in each subset. When considered over sparse random graphs, the phase structure of the graph bisection problem displays certain familiar properties, but also some surprises. It is known that when the mean degree is below the critical value of 2 log 2, the cutsize is zero with high probability. We study how the minimum cutsize increases with mean degree above this critical threshold, finding a new analytical upper bound that improves considerably upon previous bounds. Combined with recent results on expander graphs, our bound suggests the unusual scenario that random graph bisection is replica symmetric up to and beyond the critical threshold, with a replica symmetry breaking transition possibly taking place above the threshold. An intriguing algorithmic consequence is that although t...
Feed Source: arxiv.org

Game Download: SKIP-BO Castaway Caper - Explore a remote island teeming with SKIP-BO fun in SKIP-BO Castaway Caper! [Win XP / Vista]...
Feed Source: games.ncbuy.com

Game Download: Cosmic Switch Deluxe - The more combos you make in Cosmic Switch Deluxe, the more you can outwit your opponents. [Win 2000 / XP / Vista]...
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Game Download: Cooking Dash - A cooking frenzy with DinerTown drama! [Win XP / Vista]...
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Game Download: Pakoombo - Help a friendly family save their island home in Pakoombo! [Win XP / Vista]...
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Game Download: Deep Voyage - Gather resources to create an amazing undersea garden! [Win XP / Vista]...
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Game Download: Dress Up Rush - Sell the newest, hottest styles in your very own fashion boutique! [Win 98 / 2000 / ME / XP / Vista]...
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Game Download: Miss Chic - A vivid, stylish, glamorous girls' casual style game. [Win 2000 / XP / Vista]...
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Game Download: Mystery of Unicorn Castle - Search the rooms of a spooky castle to reveal the mystery of the Unicorn! [Win 98 / 2000 / ME / XP / Vista]...
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Game Download: Cinema Tycoon 2 - Build an empire on cold drinks, hot popcorn and the latest blockbuster films! [Win 2000 / XP / Vista]...
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Game Download: Delicious - Emily's Tea Garden - Join Emily for more fast-paced fun in Delicious - Emily's Tea Garden. [Win XP / Vista]...
Feed Source: games.ncbuy.com

Game Download: Sid Meier's Civilization IV: Colonization - The third offering in the award winning Civilization IV series. [Win 2000 / XP / Vista]...
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Game Download: Sid Meier's Railroads! - The greatest railroad building game of all time is back from Sid Meier! [Win 2000 / XP / Vista]...
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Game Download: Super Jigsaw Pets - 50 adorable images of playful pals [Win 9x / 2000 / ME / XP / Vista]...
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Game Download: Super Jigsaw Retro - Turn back the clock with this nostalgic collection of jigsaws. [Win 2000 / XP / Vista]...
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Game Download: Super Jigsaw Beach Holiday - Send your brain on vacation with these gorgeous jigsaws. [Win 2000 / XP / Vista]...
Feed Source: games.ncbuy.com

SINR Diagrams: Towards Algorithmically Usable SINR Models of Wireless Networks. (arXiv:0811.3284v1 [cs.NI]) - The rules governing the availability and quality of connections in a wireless network are described by physical models such as the signal-to-interference & noise ratio (SINR) model. For a collection of simultaneously transmitting stations in the plane, it is possible to identify a reception zone for each station, consisting of the points where its transmission is received correctly. The resulting SINR diagram partitions the plane into a recep...
Feed Source: arxiv.org

Faster Retrieval with a Two-Pass Dynamic-Time-Warping Lower Bound. (arXiv:0811.3301v1 [cs.DB]) - The Dynamic Time Warping (DTW) is a popular similarity measure between time series. The DTW fails to satisfy the triangle inequality and its computation requires quadratic time. Hence, to find closest neighbors quickly, we use bounding techniques. We can avoid most DTW computations with an inexpensive lower bound (LB Keogh). We compare LB Keogh with a tighter lower bound (LB Improved). We find that LB Improved-based search is faster. As an exampl...
Feed Source: arxiv.org

chi2TeX Semi-automatic translation from chiwriter to LaTeX. (arXiv:0811.3328v1 [cs.SE]) - Semi-automatic translation of math-filled book from obsolete ChiWriter format to LaTeX. Is it possible? Idea of criterion whether to use automatic or hand mode for translation. Illustrations. ...
Feed Source: arxiv.org

Belief functions on lattices. (arXiv:0811.3373v1 [cs.DM]) - We extend the notion of belief function to the case where the underlying structure is no more the Boolean lattice of subsets of some universal set, but any lattice, which we will endow with a minimal set of properties according to our needs. We show that all classical constructions and definitions (e.g., mass allocation, commonality function, plausibility functions, necessity measures with nested focal elements, possibility distributions, Dempste...
Feed Source: arxiv.org

Broadcasting in Prefix Space: P2P Data Dissemination with Predictable Performance. (arXiv:0811.3387v1 [cs.NI]) - A broadcast mode may augment peer-to-peer overlay networks with an efficient, scalable data replication function, but may also give rise to a virtual link layer in VPN-type solutions. We introduce a simple broadcasting mechanism that operates in the prefix space of distributed hash tables without signaling. This paper concentrates on the performance analysis of the prefix flooding scheme. Starting from simple models of recursive $k$-ary trees, we...
Feed Source: arxiv.org

Elasticity and Viral Conductance: Unveiling Robustness in Complex Networks through Topological Characteristics. (arXiv:0811.3272v1 [cs.NI]) - The capacity to measure robustness in complex networks defines the resolve of a network to remain unaffected in the advent of classical component failures and at the onset of cryptic malicious attacks. In an effort to measure robustness, selection and definition of network metrics for robustness must be performed taking into account the specific network problem we want to prevent. To date, robustness metrics are deficient and unfortunately the fo...
Feed Source: arxiv.org

An experimental analysis of Lemke-Howson algorithm. (arXiv:0811.3247v1 [cs.DS]) - We present an experimental investigation of the performance of the Lemke-Howson algorithm, which is the most widely used algorithm for the computation of a Nash equilibrium for bimatrix games. Lemke-Howson algorithm is based upon a simple pivoting strategy, which corresponds to following a path whose endpoint is a Nash equilibrium. We analyze both the basic Lemke-Howson algorithm and a heuristic modification of it, which we designed to cope with ...
Feed Source: arxiv.org

A Rational Deconstruction of Landin's SECD Machine with the J Operator. (arXiv:0811.3231v1 [cs.PL]) - Landin's SECD machine was the first abstract machine for applicative expressions, i.e., functional programs. Landin's J operator was the first control operator for functional languages, and was specified by an extension of the SECD machine. We present a family of evaluation functions corresponding to this extension of the SECD machine, using a series of elementary transformations (transformation into continu-ation-passing style (CPS) and defuncti...
Feed Source: arxiv.org

Linear Time Approximation Schemes for the Gale-Berlekamp Game and Related Minimization Problems. (arXiv:0811.3244v1 [cs.DS]) - We design a linear time approximation scheme for the Gale-Berlekamp Switching Game and generalize it to a wider class of dense fragile minimization problems including the Nearest Codeword Problem (NCP) and Unique Games Problem. Further applications include, among other things, finding a constrained form of matrix rigidity and maximum likelihood decoding of an error correcting code. As another application of our method we give the first linear tim...
Feed Source: arxiv.org

A Cloning Pushout Approach to Term-Graph Transformation. (arXiv:0811.3400v1 [cs.LO]) - We address the problem of cyclic termgraph rewriting. We propose a new framework where rewrite rules are tuples of the form $(L,R,\tau,\sigma)$ such that $L$ and $R$ are termgraphs representing the left-hand and the right-hand sides of the rule, $\tau$ is a mapping from the nodes of $L$ to those of $R$ and $\sigma$ is a partial function from nodes of $R$ to nodes of $L$. $\tau$ describes how incident edges of the nodes in $L$ are connected in $R$...
Feed Source: arxiv.org

Sequential, Parallel, Online, and Distributed Covering. (arXiv:0807.0644v2 [cs.DS] UPDATED) - The paper presents new d-approximation algorithms for covering problems, where d is the maximum number of variables on which any constraint depends (generalizing 2-approximation algorithms for Vertex Cover). Specific results include: A d-approximation algorithm for a generalization of Covering Mixed Integer Linear Programs. This runs in nearly linear time. (Generalizes ellipsoid-based results by Carr et al). For d=2, a parallel implementation i...
Feed Source: arxiv.org

The Peculiar Phase Structure of Random Graph Bisection. (arXiv:0808.1549v2 [cond-mat.stat-mech] UPDATED) - The mincut graph bisection problem involves partitioning the n vertices of a graph into disjoint subsets, each containing exactly n/2 vertices, while minimizing the number of "cut" edges with an endpoint in each subset. When considered over sparse random graphs, the phase structure of the graph bisection problem displays certain familiar properties, but also some surprises. It is known that when the mean degree is below the critical value of 2 lo...
Feed Source: arxiv.org

This Week in Science - Martian Reservoirs | Visions from Afar | Massive Stars and MAGIC Crab Nebula | GPCR Structural Diversity | Light from Below | Promoting Polyandry | Modeling Subcellular Morphogenesis | Dinospore Control | Wnts and the Brain Vasculature | A Drive Along the Metabolic Information Highway | No Escape for Insect Pathogens | Long Live the Standard Model | Accelerated Imaging | Mussel-ing in on Evolution | University Challenge...
Feed Source: www.sciencemag.org

Editors' Choice - ECOLOGY: Harmonious Agriculture | BIOCHEMISTRY: Out of Thin Air | EVOLUTION: Fishing for Worms | CHEMISTRY: Tubular Templates | GEOLOGY: Breaking Early and Often | BIOMEDICINE: Helpful Bystanders | MOLECULAR BIOLOGY: Acting at a Distance...
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Science Scope - Obama Transition: Agencies, Meet Microscope | E Pluribus Unum | INSERM in Flux? | Stretching Out LHC Repairs | Gene Tests Under Scrutiny...
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Random Samples - BIG CHILL | SILICON SEMINAR ROOM | SLOW'S THE WAY TO GO | A FAMILY AFFAIR...
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Newsmakers - PATHWAYS INTO SCIENCE | ON CAMPUS | IN BRIEF | IN BRIEF | THREE Q'S...
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[EDITORIAL] Opening Japan Up to the World - Author: Kiyoshi Kurokawa...
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[NEWS] TECHNICAL EXCHANGES: U.S. Visa Delays on the Rise, Scientists Abroad Report - A recent slowdown in the processing of U.S. visas for foreign scientists and some seemingly arbitrary visa denials have prompted a fresh look at how to streamline the process.Author: Richard Stone...
Feed Source: www.sciencemag.org

[NEWS] ASTROPARTICLE PHYSICS: Excess Particles From Space May Hint at Dark Matter - An unexpected abundance of high-energy electrons from space could be evidence of particles of dark matter--the weighty and mysterious stuff whose gravity holds the galaxies together. But if the sightings really do point to dark matter, then physicists may have to revise their ideas about what the stuff is.Author: Adrian Cho...
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[NEWS] GLOBAL HEALTH: Malaria Drugs, the Coca-Cola Way - On 7 November, the Board of the Global Fund to Fight AIDS, Tuberculosis and Malaria voted to adopt a new financing system aimed at bringing the best malaria drugs at rock-bottom prices to the local private-sector stores where most Africans buy their drugs--by letting the market do the work.Author: Martin Enserink...
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[NEWS] CRIMINOLOGY: Study Shows How Degraded Surroundings Can Degrade Behavior - In a series of cleverly designed experiments reported in a paper published online by Science this week, researchers found that if people see one norm or rule being violated (such as graffiti or a vehicle parked illegally), they're more likely to violate others--such as littering, or even stealing.Author: Constance Holden...
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[NEWS] DEVELOPING WORLD: The New Groove in Science Aid: South-South Initiatives - In addition to helping to close the divide between the research capabilities of the northern and southern hemispheres, the 871-member Academy of Sciences for the Developing World is now focusing on another divide: the widening gap between the South's scientific haves and have-nots.Author: Robert Koenig...
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[NEWS] SYSTEMS BIOLOGY: Cast of 1000 Proteins Shines in Movies of Cancer Cells - Systems biologists describe online in Science this week how fluorescent markers and a time-lapse microscope have allowed them an unprecedented view of the fluctuating locations and levels of about 1000 proteins in individual human cancer cells.Author: Jocelyn Kaiser...
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[NEWS FOCUS] ENERGY: World Oil Crunch Looming? - Even those who believe there's plenty of oil left in the ground to meet rising demand are warning that the final crisis could come uncomfortably soon.Author: Richard A. Kerr...
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[NEWS FOCUS] SPACE: Cloudy Future for Europe's Space Plans - A string of successful missions had the European Space Agency riding high and making ambitious plans, but the worldwide financial downturn may bring it back to Earth.Author: Daniel Clery...
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[NEWS FOCUS] MYCOLOGY: Last Stand for the Body Snatcher of the Himalayas? - The caterpillar-hijacking fungus Cordyceps sinensis is touted as a natural Viagra. But overharvesting has put the peculiar parasite's back against the wall.Author: Richard Stone...
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[NEWS FOCUS] SCIENCE IN ROMANIA: Reaching for the Stars in Romania - A small association of Romanian scientists, many of them working abroad, is fed up with the slow pace of reforms in their country. And politicians are paying attention.Author: Martin Enserink...
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[NEWS FOCUS] SCIENCE IN ROMANIA: At Home in Bucharest, for Better and for Worse - In the late 1980s, communist dictator Nicolae Ceau?escu sought to demolish the Institute of Cellular Biology and Pathology (ICBP) to make way for his "House of the People." Then came the Christmas revolution of 1989. Ceau?escu didn't survive; ICBP did.Author: Martin Enserink...
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[LETTERS] Looking Beyond Head Trauma - Author: Darin T. Okuda...
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[LETTERS] Fostering a Culture of Responsible Lab Conduct - Authors: Ann M. Peiffer, Paul J. Laurienti, Christina E. Hugenschmidt...
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[LETTERS] The Path Forward for DNA Data - Authors: Paula Boddington, Naomi Hawkins, Catherine Heeney, Jantina De Vries, Jane Kaye...
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[LETTERS] Priorities Come with the Career - Author: Craig Bolon...
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[LETTERS] STEM Education Crisis: Overblown? - Author: Andrew Depristo...
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[LETTERS] Changes to NIH Grant System May Backfire - Authors: Peter D. Karp, Gavin Sherlock, John A. Gerlt, Ida Sim, Ian Paulsen, Patricia C. Babbitt, Keith Laderoute, Lawrence Hunter, Paul Sternberg, John Wooley, Philip E. Bourne...
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[LETTERS] Listening to the Ocean's Heartbeat - Authors: Elvira S. Poloczanska, Anthony J. Richardson...
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[LETTERS] Legislation Leaves Common Sense Behind - Author: Harold Scarbro...
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[BOOKS ET AL.] HISTORY OF SCIENCE: Who Scientists Are Now - Shapin's account of the development and current practice of the profession of science spotlights the researchers in the trenches rather than the big-thinkers. Author: Thomas F. Gieryn...
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[BOOKS ET AL.] AGRICULTURE: Organic and GM--Why Not? - Writing for nonspecialists, Ronald (a rice geneticist) and Adamchak (an organic farmer) argue that the best path to sustainable food production lies through a careful combination of organic farming and genetically engineered plants.Author: Mark Tester...
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[BOOKS ET AL.] EXHIBITIONS: ART: Global Perspectives - Using his sixfold perspective, Termes paints optical illusory scenes on the surfaces of spheres. Author: Barbara Jasny...
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[POLICY FORUM] POLICY: A Force for Peace in the Middle East - Support of regional scientific institutions or associations may make a difference.Author: Michael Greene...
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[PERSPECTIVES] ASTRONOMY: Gamma Rays and Neutron Stars - Satellite and ground observations provide new insights into gamma-ray emissions from neutron stars.Author: Giovanni F. Bignami...
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[PERSPECTIVES] CHEMISTRY: Interrogating Molecules - Attosecond laser pulses can reveal the complex electronic processes occurring within molecular systems.Authors: Gilles Doumy, Louis F. DiMauro...
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[PERSPECTIVES] DEVELOPMENTAL BIOLOGY: Brain Wnts for Blood Vessels - Development of the blood-brain barrier in mammals starts in the embryo, through specific molecules that induce vascular development in the neural tube.Author: Eckhard Lammert...
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[PERSPECTIVES] CHEMISTRY: Coming Soon to a Library Near You? - Conservation efforts will be aided by a tool that facilitates surveys of the condition of paper in libraries, archives, and museums.Author: Jan Wouters...
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[PERSPECTIVES] PHYSICS: The Weight of the World Is Quantum Chromodynamics - Ab initio calculations of the proton and neutron masses have now been achieved, a milestone in a 30-year effort of theoretical and computational physics.Author: Andreas S. Kronfeld...
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[PERSPECTIVES] MICROBIOLOGY: Rogue Insect Immunity - Insects use a variety of strategies to fight pathogens at different stages of infection, which may guide antimicrobial development for human use.Authors: David S. Schneider, Moria C. Chambers...
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[REVIEWS] The Psychology of Transcending the Here and Now - Authors: Nira Liberman, Yaacov Trope...
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[BREVIA] Fossil Pollen as a Guide to Conservation in the Galápagos - Fossil pollen shows that six plant species in the Gal'apagos, presumed to be invasive, had actually been native to the islands for thousands of years before human colonization. Authors: Jacqueline F. N. van Leeuwen, Cynthia A. Froyd, W. O. van der Knaap, Emily E. Coffey, Alan Tye, Katherine J. Willis...
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[RESEARCH ARTICLES] Time-Resolved Dynamics in N2O4 Probed Using High Harmonic Generation - Electrons can be ejected from multiple orbitals of N2O4 by exploiting different stages in its excited vibrations, yielding an attosecond light probe of molecular dynamics. Authors: Wen Li, Xibin Zhou, Robynne Lock, Serguei Patchkovskii, Albert Stolow, Henry C. Kapteyn, Margaret M. Murnane...
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[RESEARCH ARTICLES] The 2.6 Angstrom Crystal Structure of a Human A2A Adenosine Receptor Bound to an Antagonist - The ligand binding pocket of the caffeine-binding human adenosine receptor has a different position and orientation than that of other G protein-linked receptors. Authors: Veli-Pekka Jaakola, Mark T. Griffith, Michael A. Hanson, Vadim Cherezov, Ellen Y. T. Chien, J. Robert Lane, Adriaan P. IJzerman, Raymond C. Stevens...
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[REPORTS] The Fermi Gamma-Ray Space Telescope Discovers the Pulsar in the Young Galactic Supernova Remnant CTA 1 - The Fermi Space Telescope has detected a gamma-ray pulsar associated with a young supernova remnant, implying that such stars may be unidentified gamma-ray sources. Authors: A. A. Abdo, M. Ackermann, W. B. Atwood, L. Baldini, J. Ballet, G. Barbiellini, M. G. Baring, D. Bastieri, B. M. Baughman, K. Bechtol, R. Bellazzini, B. Berenji, R. D. Blandford, E. D. Bloom, G. Bogaert, E. Bonamente, A. W. Borgland, J. Bregeon, A. Brez, M. Brigida, P. Brue...
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[REPORTS] Observation of Pulsed ?-Rays Above 25 GeV from the Crab Pulsar with MAGIC - The MAGIC telescope has detected higher-energy, pulsed gamma rays from the Crab pulsar and a threshold suggesting that they are emitted from the outer magnetosphere. Authors: The MAGIC Collaboration, E. Aliu, H. Anderhub, L. A. Antonelli, P. Antoranz, M. Backes, C. Baixeras, J. A. Barrio, H. Bartko, D. Bastieri, J. K. Becker, W. Bednarek, K. Berger, E. Bernardini, C. Bigongiari, A. Biland, R. K. Bock, G. Bonnoli, P. Bordas, V. Bosch-Ramon, T. ...
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[REPORTS] Ab Initio Determination of Light Hadron Masses - A quantum chromodynamics calculation that includes a full description of quarks and their interactions accurately determines the masses of protons, neutrons and other light hadrons. Authors: S. Dürr, Z. Fodor, J. Frison, C. Hoelbling, R. Hoffmann, S. D. Katz, S. Krieg, T. Kurth, L. Lellouch, T. Lippert, K. K. Szabo, G. Vulvert...
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[REPORTS] 4D Imaging of Transient Structures and Morphologies in Ultrafast Electron Microscopy - Imaging with single electrons can track structural dynamics of gold and graphite in real space with femtosecond temporal resolution and angstrom spatial resolution. Authors: Brett Barwick, Hyun Soon Park, Oh-Hoon Kwon, J. Spencer Baskin, Ahmed H. Zewail...
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[REPORTS] High Harmonic Generation from Multiple Orbitals in N2 - Electron ejection from multiple N2 orbitals, controlled by the molecule's orientation relative to a laser, produces attosecond light spectra that can reveal molecular dynamics. Authors: Brian K. McFarland, Joseph P. Farrell, Philip H. Bucksbaum, Markus Gühr...
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[REPORTS] Radar Sounding Evidence for Buried Glaciers in the Southern Mid-Latitudes of Mars - Radar data from the Mars Reconnaissance Orbiter show that a series of lobate landforms at low latitudes are composed primarily of massive ice covered by debris. Authors: John W. Holt, Ali Safaeinili, Jeffrey J. Plaut, James W. Head, Roger J. Phillips, Roberto Seu, Scott D. Kempf, Prateek Choudhary, Duncan A. Young, Nathaniel E. Putzig, Daniela Biccari, Yonggyu Gim...
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[REPORTS] Variation in Evolutionary Patterns Across the Geographic Range of a Fossil Bivalve - Within a fossil bivalve genus, evolution tended to occur as a random walk at the highest latitudes and to be in stasis mode in deep marine environments. Authors: Melissa Grey, James W. Haggart, Paul L. Smith...
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[REPORTS] Selfish Genetic Elements Promote Polyandry in a Fly - Genes that confer a deleterious sex ratio in Drosophila also decrease male fertility and promote repetitive mating in females, providing a possible explanation of polyandry. Authors: T. A. R. Price, D. J. Hodgson, Z. Lewis, G. D. D. Hurst, N. Wedell...
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[REPORTS] Regulation of Microtubule Dynamics by Reaction Cascades Around Chromosomes - A reaction-diffusion model involving regulatory molecules and a microtubule-stabilizing phosphoprotein predicts the spatial distribution of microtubules during cell division. Authors: Chaitanya A. Athale, Ana Dinarina, Maria Mora-Coral, Céline Pugieux, Francois Nedelec, Eric Karsenti...
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[REPORTS] Canonical Wnt Signaling Regulates Organ-Specific Assembly and Differentiation of CNS Vasculature - In mice, two specialized ligands for a key developmental signaling pathway are produced by neuroepithelial cells and direct endothelial cells to form the blood-brain barrier. Authors: Jan M. Stenman, Jay Rajagopal, Thomas J. Carroll, Makoto Ishibashi, Jill McMahon, Andrew P. McMahon...
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[REPORTS] Regulation of Pancreatic ? Cell Mass by Neuronal Signals from the Liver - In obese mice, fat tissue stimulates proliferation of insulin-producing pancreatic cells via a neural relay through the liver, contributing to symptoms of metabolic syndrome. Authors: Junta Imai, Hideki Katagiri, Tetsuya Yamada, Yasushi Ishigaki, Toshinobu Suzuki, Hirohito Kudo, Kenji Uno, Yutaka Hasegawa, Junhong Gao, Keizo Kaneko, Hisamitsu Ishihara, Akira Niijima, Masamitsu Nakazato, Tomoichiro Asano, Yasuhiko Minokoshi, Yoshitomo Oka...
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[REPORTS] Control of Toxic Marine Dinoflagellate Blooms by Serial Parasitic Killers - As successive populations of protists have caused summer red tides in France, each has been killed off by a distinct, persistent parasite, establishing a self-regulating ecosystem. Authors: Aurelie Chambouvet, Pascal Morin, Dominique Marie, Laure Guillou...
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[REPORTS] Antimicrobial Defense and Persistent Infection in Insects - Flies fight some infections by quickly engulfing bacteria in phagocytic cells then deploying antimicrobial peptides, a system that avoids bacterial resistance. Authors: Eleanor R. Haine, Yannick Moret, Michael T. Siva-Jothy, Jens Rolff...
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[REPORTS] Multi-University Research Teams: Shifting Impact, Geography, and Stratification in Science - Over the past 30 years, scientific papers have become increasingly likely to be written by teams of authors from more than one of a small number of elite universities. Authors: Benjamin F. Jones, Stefan Wuchty, Brian Uzzi...
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[SPECIAL FEATUREs] SCIENCE CAREERS: Finance's Quant(um) Mechanics - One of the earliest "alternative" science careers, quantitative finance is now deeply embedded in the world's finance industry.Author: Alaina G. Levine...
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[SPECIAL FEATUREs] SCIENCE CAREERS: Analyzing Scientific Investments - A background in science can be an advantage for analysts charged with determining the value of science-based companies.Author: Amarendra Swarup...
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