Showing papers by "University of California, Santa Barbara published in 2004"
TL;DR: Highly dynamic mitotic-spindle microtubules are among the most successful targets for anticancer therapy, and it is now known that at lower concentrations, microtubule-targeted drugs can suppress micro Tubule dynamics without changingmicrotubule mass; this action leads to mitotic block and apoptosis.
Abstract: Highly dynamic mitotic-spindle microtubules are among the most successful targets for anticancer therapy. Microtubule-targeted drugs, including paclitaxel and Vinca alkaloids, were previously considered to work primarily by increasing or decreasing the cellular microtubule mass. Although these effects might have a role in their chemotherapeutic actions, we now know that at lower concentrations, microtubule-targeted drugs can suppress microtubule dynamics without changing microtubule mass; this action leads to mitotic block and apoptosis. In addition to the expanding array of chemically diverse antimitotic agents, some microtubule-targeted drugs can act as vascular-targeting agents, rapidly depolymerizing microtubules of newly formed vasculature to shut down the blood supply to tumours.
4,007 citations
Goddard Space Flight Center1, University of Milan2, Brera Astronomical Observatory3, University College London4, Pennsylvania State University5, University of Leicester6, Sonoma State University7, University of California, Berkeley8, Universities Space Research Association9, National Research Council10, University of Southampton11, Los Alamos National Laboratory12, National Radio Astronomy Observatory13, Space Telescope Science Institute14, Max Planck Society15, California Institute of Technology16, University of Texas at Austin17, French Alternative Energies and Atomic Energy Commission18, University of Toronto19, University of Maryland, College Park20, Princeton University21, Lawrence Livermore National Laboratory22, University of Cambridge23, University of California, Santa Barbara24, Rice University25, University of Tokyo26, Saitama University27, University of Florence28
TL;DR: The Swift mission as discussed by the authors is a multi-wavelength observatory for gamma-ray burst (GRB) astronomy, which is a first-of-its-kind autonomous rapid-slewing satellite for transient astronomy and pioneers the way for future rapid-reaction and multiwavelength missions.
Abstract: The Swift mission, scheduled for launch in 2004, is a multiwavelength observatory for gamma-ray burst (GRB) astronomy. It is a first-of-its-kind autonomous rapid-slewing satellite for transient astronomy and pioneers the way for future rapid-reaction and multiwavelength missions. It will be far more powerful than any previous GRB mission, observing more than 100 bursts yr � 1 and performing detailed X-ray and UV/optical afterglow observations spanning timescales from 1 minute to several days after the burst. The objectives are to (1) determine the origin of GRBs, (2) classify GRBs and search for new types, (3) study the interaction of the ultrarelativistic outflows of GRBs with their surrounding medium, and (4) use GRBs to study the early universe out to z >10. The mission is being developed by a NASA-led international collaboration. It will carry three instruments: a newgeneration wide-field gamma-ray (15‐150 keV) detector that will detect bursts, calculate 1 0 ‐4 0 positions, and trigger autonomous spacecraft slews; a narrow-field X-ray telescope that will give 5 00 positions and perform spectroscopy in the 0.2‐10 keV band; and a narrow-field UV/optical telescope that will operate in the 170‐ 600 nm band and provide 0B3 positions and optical finding charts. Redshift determinations will be made for most bursts. In addition to the primary GRB science, the mission will perform a hard X-ray survey to a sensitivity of � 1m crab (� 2;10 � 11 ergs cm � 2 s � 1 in the 15‐150 keV band), more than an order of magnitude better than HEAO 1 A-4. A flexible data and operations system will allow rapid follow-up observations of all types of
3,753 citations
TL;DR: In this article, the authors argue that there is sufficient research evidence to make any reasonable person skeptical about the benefits of discovery learning as a preferred instructional method and that the constructivist view of learning may be best supported by methods of instruction that involve cognitive activity rather than behavioral activity, instructional guidance rather than pure discovery, and curricular focus rather than unstructured exploration.
Abstract: The author's thesis is that there is sufficient research evidence to make any reasonable person skeptical about the benefits of discovery learning--practiced under the guise of cognitive constructivism or social constructivism--as a preferred instructional method. The author reviews research on discovery of problem-solving rules culminating in the 1960s, discovery of conservation strategies culminating in the 1970s, and discovery of LOGO programming strategies culminating in the 1980s. In each case, guided discovery was more effective than pure discovery in helping students learn and transfer. Overall, the constructivist view of learning may be best supported by methods of instruction that involve cognitive activity rather than behavioral activity, instructional guidance rather than pure discovery, and curricular focus rather than unstructured exploration.
2,380 citations
TL;DR: A complete new conceptual model of the soil N cycle needs to incorporate recent research on plant–microbe competition and microsite processes to explain the dynamics of N across the wide range of N availability found in terrestrial ecosystems.
Abstract: Until recently, the common view of the terrestrial nitrogen cycle had been driven by two core assumptions—plants use only inorganic N and they compete poorly against soil microbes for N. Thus, plants were thought to use N that microbes “left over,” allowing the N cycle to be divided cleanly into two pieces—the microbial decomposition side and the plant uptake and use side. These were linked by the process of net mineralization. Over the last decade, research has changed these views. N cycling is now seen as being driven by the depolymerization of N-containing polymers by microbial (including mycorrhizal) extracellular enzymes. This releases organic N-containing monomers that may be used by either plants or microbes. However, a complete new conceptual model of the soil N cycle needs to incorporate recent research on plant–microbe competition and microsite processes to explain the dynamics of N across the wide range of N availability found in terrestrial ecosystems. We discuss the evolution of thinking abou...
2,126 citations
TL;DR: In this paper, the authors detected and imaged electron-spin polarization near the edges of a semiconductor channel with the use of Kerr rotation microscopy, consistent with the predictions of the spin Hall effect.
Abstract: Electrically induced electron-spin polarization near the edges of a semiconductor channel was detected and imaged with the use of Kerr rotation microscopy The polarization is out-of-plane and has opposite sign for the two edges, consistent with the predictions of the spin Hall effect Measurements of unstrained gallium arsenide and strained indium gallium arsenide samples reveal that strain modifies spin accumulation at zero magnetic field A weak dependence on crystal orientation for the strained samples suggests that the mechanism is the extrinsic spin Hall effect
1,999 citations
University of Washington1, University of Wisconsin–Milwaukee2, École Normale Supérieure3, University of British Columbia4, University of Wisconsin-Madison5, Princeton University6, Martek Biosciences Corporation7, University of California, Santa Barbara8, University of Melbourne9, University of California, San Diego10, Sandia National Laboratories11, University of California, Santa Cruz12, University of Regensburg13, Oak Ridge National Laboratory14, University of Hull15, Joint Genome Institute16, Academy of Sciences of the Czech Republic17, University of Massachusetts Medical School18, Woods Hole Oceanographic Institution19, Alfred Wegener Institute for Polar and Marine Research20, San Francisco State University21, University of California, Berkeley22
TL;DR: The 34 million-base-pair draft nuclear genome of the marine diatom Thalassiosira pseudonana and its 129 thousand-base pair plastid and 44 thousand base-pair mitochondrial genomes were reported in this article.
Abstract: Diatoms are unicellular algae with plastids acquired by secondary endosymbiosis. They are responsible for approximately 20% of global carbon fixation. We report the 34 million-base pair draft nuclear genome of the marine diatom Thalassiosira pseudonana and its 129 thousand-base pair plastid and 44 thousand-base pair mitochondrial genomes. Sequence and optical restriction mapping revealed 24 diploid nuclear chromosomes. We identified novel genes for silicic acid transport and formation of silica-based cell walls, high-affinity iron uptake, biosynthetic enzymes for several types of polyunsaturated fatty acids, use of a range of nitrogenous compounds, and a complete urea cycle, all attributes that allow diatoms to prosper in aquatic environments.
1,945 citations
TL;DR: In this paper, the authors apply the plasmon hybridization method to nanoparticle dimers, providing a simple and intuitive description of how the energy and excitation cross sections of dimer plasmons depend on nanoparticle separation.
Abstract: We apply the recently developed plasmon hybridization method to nanoparticle dimers, providing a simple and intuitive description of how the energy and excitation cross sections of dimer plasmons depend on nanoparticle separation. We show that the dimer plasmons can be viewed as bonding and antibonding combinations, i.e., hybridization of the individual nanoparticle plasmons. The calculated plasmon energies are compared with results from FDTD simulations.
1,577 citations
Conservation International1, University of California, Santa Barbara2, World Agroforestry Centre3, Sapienza University of Rome4, University of Port Elizabeth5, BirdLife International6, Universidade Federal de Minas Gerais7, University of Sheffield8, Pontifical Catholic University of Chile9, Department of Environment and Conservation10, University of Idaho11, University of Cape Town12, Chinese Academy of Sciences13
TL;DR: It is shown that the global network of protected areas is far from complete, and the inadequacy of uniform—that is, ‘one size fits all’—conservation targets is demonstrated, in the first global gap analysis assessing the effectiveness ofprotected areas in representing species diversity.
Abstract: The Fifth World Parks Congress in Durban, South Africa, announced in September 2003 that the global network of protected areas now covers 11.5% of the planet's land surface. This surpasses the 10% target proposed a decade earlier, at the Caracas Congress, for 9 out of 14 major terrestrial biomes. Such uniform targets based on percentage of area have become deeply embedded into national and international conservation planning. Although politically expedient, the scientific basis and conservation value of these targets have been questioned. In practice, however, little is known of how to set appropriate targets, or of the extent to which the current global protected area network fulfils its goal of protecting biodiversity. Here, we combine five global data sets on the distribution of species and protected areas to provide the first global gap analysis assessing the effectiveness of protected areas in representing species diversity. We show that the global network is far from complete, and demonstrate the inadequacy of uniform--that is, 'one size fits all'--conservation targets.
1,344 citations
TL;DR: A meta-analysis of the plant invasions literature concludes that ecological interactions rarely enable communities to resist invasion, but instead constrain the abundance of invasive species once they have successfully established.
Abstract: Biotic resistance describes the ability of resident species in a community to reduce the success of exotic invasions. Although resistance is a well-accepted phenomenon, less clear are the processes that contribute most to it, and whether those processes are strong enough to completely repel invaders. Current perceptions of strong, competition-driven biotic resistance stem from classic ecological theory, Elton’s formulation of ecological resistance, and the general acceptance of the enemies-release hypothesis. We conducted a meta-analysis of the plant invasions literature to quantify the contribution of resident competitors, diversity, herbivores and soil fungal communities to biotic resistance. Results indicated large negative effects of all factors except fungal communities on invader establishment and performance. Contrary to predictions derived from the natural enemies hypothesis, resident herbivores reduced invasion success as effectively as resident competitors. Although biotic resistance significantly reduced the establishment of individual invaders, we found little evidence that species interactions completely repelled invasions. We conclude that ecological interactions rarely enable communities to resist invasion, but instead constrain the abundance of invasive species once they have successfully established.
1,311 citations
TL;DR: For the Green-Schwarz superstring, this article showed that the world sheet theory may be exactly solvable in the presence of nonlocal classically conserved charges of the type that exist in integrable field theories.
Abstract: Attempts to solve Yang-Mills theory must eventually face the problem of analyzing the theory at intermediate values of the coupling constant. In this regime neither perturbation theory nor the gravity dual are adequate, and one must consider the full string theory in the appropriate background. We suggest that in some nontrivial cases the world sheet theory may be exactly solvable. For the Green-Schwarz superstring on ${\mathrm{AdS}}_{5}\ifmmode\times\else\texttimes\fi{}{\mathrm{S}}^{5}$ we find an infinite set of nonlocal classically conserved charges of the type that exist in integrable field theories.
1,311 citations
TL;DR: The already significant impact this field has made on the administration of various pharmaceuticals is discussed; limitations of the current technology are explored; methods under exploration for overcoming these limitations and the challenges ahead are discussed.
Abstract: The past twenty five years have seen an explosion in the creation and discovery of new medicinal agents. Related innovations in drug delivery systems have not only enabled the successful implementation of many of these novel pharmaceuticals, but have also permitted the development of new medical treatments with existing drugs. The creation of transdermal delivery systems has been one of the most important of these innovations, offering a number of advantages over the oral route. In this article, we discuss the already significant impact this field has made on the administration of various pharmaceuticals; explore limitations of the current technology; and discuss methods under exploration for overcoming these limitations and the challenges ahead.
TL;DR: In this paper, the authors leveraged institutional theory by proposing that stakeholders, including governments, regulators, customers, competitors, community and environmental interest groups, and industry associations, impose coercive and normative pressures on firms.
Abstract: Despite burgeoning research on companies' environmental strategies and environmental management practices, it remains unclear why some firms adopt environmental management practices beyond regulatory compliance. This paper leverages institutional theory by proposing that stakeholders – including governments, regulators, customers, competitors, community and environmental interest groups, and industry associations – impose coercive and normative pressures on firms. However, the way in which managers perceive and act upon these pressures at the plant level depends upon plant- and parent-company-specific factors, including their track record of environmental performance, the competitive position of the parent company and the organizational structure of the plant. Beyond providing a framework of how institutional pressures influence plants' environmental management practices, various measures are proposed to quantify institutional pressures, key plant-level and parent-company-level characteristics and plant-level environmental management practices. Copyright © 2004 John Wiley & Sons, Ltd and ERP Environment.
University of Pittsburgh1, State Street Corporation2, University of Chicago3, Monash University4, University of California, Irvine5, University of Maryland, College Park6, Dalhousie University7, University of California, Santa Barbara8, University of Akron9, Washington State University10, Duke University11
TL;DR: A change in approach is needed to determine whether pollen limitation reflects random fluctuations around a pollen–resource equilibrium, an adaptation to stochastic pollination environments, or a chronic syndrome caused by an environmental perturbation.
Abstract: Determining whether seed production is pollen limited has been an area of intensive empirical study over the last two decades. Yet current evidence does not allow satisfactory assessment of the causes or consequences of pollen limitation. Here, we critically evaluate existing theory and issues concerning pollen limitation. Our main conclusion is that a change in approach is needed to determine whether pollen limitation reflects random fluctuations around a pollen–resource equilibrium, an adaptation to stochastic pollination environments, or a chronic syndrome caused by an environmental perturbation. We formalize and extend D. Haig and M. Westoby's conceptual model, and illustrate its use in guiding research on the evolutionary consequences of pollen limitation, i.e., whether plants evolve or have evolved to ameliorate pollen limitation. This synthesis also reveals that we are only beginning to understand when and how pollen limitation at the plant level translates into effects on plant population dynamics...
TL;DR: This work states that theoretical approaches to complex engineered systems can provide guidelines for investigating cellular robustness and may be a key to understanding cellular complexity, elucidating design principles, and fostering closer interactions between experimentation and theory.
TL;DR: In this article, the authors developed an integrative framework for understanding the impact of detritus on food web dynamics, emphasizing the ontogeny and heterogeneity of detribus and the various ways that explicit inclusion of the detrital dynamics alters generalizations about the structure and functioning of food webs.
Abstract: Traditional approaches to the study of food webs emphasize the transfer of local primary productivity in the form of living plant organic matter across trophic levels. However, dead organic matter, or detritus, a common feature of most ecosystems plays a frequently overlooked role as a dynamic heterogeneous resource and habitat for many species. We develop an integrative framework for understanding the impact of detritus that emphasizes the ontogeny and heterogeneity of detritus and the various ways that explicit inclusion of detrital dynamics alters generalizations about the structure and functioning of food webs. Through its influences on food web composition and dynamics, detritus often increases system stability and persistence, having substantial effects on trophic structure and biodiversity. Inclusion of detrital heterogeneity in models of food web dynamics is an essential new direction for ecological research.
TL;DR: This work identifies the nature of the ferroelectric phase transition in the hexagonal manganite, YMnO3, using a combination of single-crystal X-ray diffraction, thorough structure analysis and first-principles density-functional calculations, and suggests an avenue for designing novel magnetic ferroelectrics.
Abstract: Understanding the ferroelectrocity in magnetic ferroelectric oxides is of both fundamental and technological importance. Here, we identify the nature of the ferroelectric phase transition in the hexagonal manganite, YMnO3, using a combination of single-crystal X-ray diffraction, thorough structure analysis and first-principles density-functional calculations. The ferroelectric phase is characterized by a buckling of the layered MnO5 polyhedra, accompanied by displacements of the Y ions, which lead to a net electric polarization. Our calculations show that the mechanism is driven entirely by electrostatic and size effects, rather than the usual changes in chemical bonding associated with ferroelectric phase transitions in perovskite oxides. As a result, the usual indicators of structural instability, such as anomalies in Born effective charges on the active ions, do not hold. In contrast to the chemically stabilized ferroelectrics, this mechanism for ferroelectricity permits the coexistence of magnetism and ferroelectricity, and so suggests an avenue for designing novel magnetic ferroelectrics.
TL;DR: In this article, the authors make use of the combined distributions of silicic acid and nitrate to trace the main nutrient return path from deep waters by upwelling in the Southern Ocean and subsequent entrainment into subantarctic mode water.
Abstract: The ocean's biological pump strips nutrients out of the surface waters and exports them into the thermocline and deep waters. If there were no return path of nutrients from deep waters, the biological pump would eventually deplete the surface waters and thermocline of nutrients; surface biological productivity would plummet. Here we make use of the combined distributions of silicic acid and nitrate to trace the main nutrient return path from deep waters by upwelling in the Southern Ocean1 and subsequent entrainment into subantarctic mode water. We show that the subantarctic mode water, which spreads throughout the entire Southern Hemisphere2,3 and North Atlantic Ocean3, is the main source of nutrients for the thermocline. We also find that an additional return path exists in the northwest corner of the Pacific Ocean, where enhanced vertical mixing, perhaps driven by tides4, brings abyssal nutrients to the surface and supplies them to the thermocline of the North Pacific. Our analysis has important implications for our understanding of large-scale controls on the nature and magnitude of low-latitude biological productivity and its sensitivity to climate change.
University of Arizona1, Yale University2, University of California, Santa Barbara3, Natural Resources Research Institute4, Colorado State University5, Carnegie Institution for Science6, University of California, Santa Cruz7, University of Nevada, Las Vegas8, Texas Tech University9, University of Tennessee10, University of New Mexico11, University of Buenos Aires12, University of California, Berkeley13, Northern Arizona University14, Columbia University15, University of Colorado Boulder16, University of Wyoming17
TL;DR: It is shown that RUE decreases across biomes as mean annual precipitation increases, and during the driest years at each site, there is convergence to a common maximum RUE (RUEmax) that is typical of arid ecosystems.
Abstract: Water availability limits plant growth and production in almost all terrestrial ecosystems. However, biomes differ substantially in sensitivity of aboveground net primary production (ANPP) to between-year variation in precipitation. Average rain-use efficiency (RUE; ANPP/precipitation) also varies between biomes, supposedly because of differences in vegetation structure and/or biogeochemical constraints. Here we show that RUE decreases across biomes as mean annual precipitation increases. However, during the driest years at each site, there is convergence to a common maximum RUE (RUE(max)) that is typical of arid ecosystems. RUE(max) was also identified by experimentally altering the degree of limitation by water and other resources. Thus, in years when water is most limiting, deserts, grasslands and forests all exhibit the same rate of biomass production per unit rainfall, despite differences in physiognomy and site-level RUE. Global climate models predict increased between-year variability in precipitation, more frequent extreme drought events, and changes in temperature. Forecasts of future ecosystem behaviour should take into account this convergent feature of terrestrial biomes.
TL;DR: In this paper, the authors proposed a new normalized information distance based on the non-computable notion of Kolmogorov complexity, which minorizes every computable distance in the class (that is, it is universal in that it discovers all computable similarities).
Abstract: A new class of distances appropriate for measuring similarity relations between sequences, say one type of similarity per distance, is studied. We propose a new "normalized information distance," based on the noncomputable notion of Kolmogorov complexity, and show that it is in this class and it minorizes every computable distance in the class (that is, it is universal in that it discovers all computable similarities). We demonstrate that it is a metric and call it the similarity metric . This theory forms the foundation for a new practical tool. To evidence generality and robustness, we give two distinctive applications in widely divergent areas using standard compression programs like gzip and GenCompress. First, we compare whole mitochondrial genomes and infer their evolutionary history. This results in a first completely automatic computed whole mitochondrial phylogeny tree. Secondly, we fully automatically compute the language tree of 52 different languages.
TL;DR: This paper provides a collection of results that can be viewed as extensions of LaSalle's Invariance Principle to certain classes of switched linear systems that can deduce asymptotic stability using multiple Lyapunov functions whose Lie derivatives are only negative semidefinite.
Abstract: This paper addresses the uniform stability of switched linear systems, where uniformity refers to the convergence rate of the multiple solutions that one obtains as the switching signal ranges over a given set. We provide a collection of results that can be viewed as extensions of LaSalle's Invariance Principle to certain classes of switched linear systems. Using these results one can deduce asymptotic stability using multiple Lyapunov functions whose Lie derivatives are only negative semidefinite. Depending on the regularity assumptions placed on the switching signals, one may be able to conclude just asymptotic stability or (uniform) exponential stability. We show by counter-example that the results obtained are tight.
TL;DR: It is revealed that relationship concerns accounted for the cultural differences in use of support seeking and the potential benefits and liabilities of seeking social support.
Abstract: Are Asians and Asian Americans more or less likely to seek social support for dealing with stress than European Americans? On the one hand, the collectivist orientation of Asian countries might favor the sharing of stressful problems; on the other hand, efforts to maintain group harmony might discourage such efforts. In 2 studies, Koreans (Study 1) and Asians and Asian Americans in the United States (Study 2) reported using social support less for coping with stress than European Americans. Study 3 examined potential explanations for these effects and revealed that relationship concerns accounted for the cultural differences in use of support seeking. Discussion centers on the potential benefits and liabilities of seeking social support.
TL;DR: In this article, the authors measure the economic impact of climate change on US agricultural land by estimating the effect of the presumably random year-to-year variation in temperature and precipitation on agricultural profits.
Abstract: This paper measures the economic impact of climate change on US agricultural land by estimating the effect of the presumably random year-to-year variation in temperature and precipitation on agricultural profits. Using long-run climate change predictions from the Hadley 2 Model, the preferred estimates indicate that climate change will lead to a $1.3 billion (2002$) or 4.0% increase in annual profits. The 95% confidence interval ranges from -$0.5 billion to $3.1 billion and the impact is robust to a wide variety of specification checks, so large negative or positive effects are unlikely. There is considerable heterogeneity in the effect across the country with California's predicted impact equal to -$0.75 billion (or nearly 15% of state agricultural profits). Further, the analysis indicates that the predicted increases in temperature and precipitation will have virtually no effect on yields among the most important crops, which suggest that the small effect on profits are not due to short-run price increases. The paper also implements the hedonic approach that is predominant in the previous literature and finds that it may be unreliable, because it produces estimates of the effect of climate change that are extremely sensitive to seemingly minor decisions about the appropriate control variables, sample and weighting. Overall, the findings contradict the popular view that climate change will have substantial negative welfare consequences for the US agricultural sector.
TL;DR: A new, quasi-local framework was introduced to analyze diverse facets of black holes in a unified manner that has introduced a more physical setting for black hole thermodynamics, suggested a phenomenological model for hairy black holes, provided novel techniques to extract physics from numerical simulations, and led to new laws governing the dynamics ofblack holes in exact general relativity.
Abstract: Over the past three decades, black holes have played an important role in quantum gravity, mathematical physics, numerical relativity and gravitational wave phenomenology. However, conceptual settings and mathematical models used to discuss them have varied considerably from one area to another. Over the last five years a new, quasi-local framework was introduced to analyze diverse facets of black holes in a unified manner. In this framework, evolving black holes are modelled by dynamical horizons and black holes in equilibrium by isolated horizons. We review basic properties of these horizons and summarize applications to mathematical physics, numerical relativity, and quantum gravity. This paradigm has led to significant generalizations of several results in black hole physics. Specifically, it has introduced a more physical setting for black hole thermodynamics and for black hole entropy calculations in quantum gravity, suggested a phenomenological model for hairy black holes, provided novel techniques to extract physics from numerical simulations, and led to new laws governing the dynamics of black holes in exact general relativity.
21 Jun 2004
TL;DR: The Kepler scientific workflow system provides domain scientists with an easy-to-use yet powerful system for capturing scientific workflows (SWFs), a formalization of the ad-hoc process that a scientist may go through to get from raw data to publishable results.
Abstract: Most scientists conduct analyses and run models in several different software and hardware environments, mentally coordinating the export and import of data from one environment to another. The Kepler scientific workflow system provides domain scientists with an easy-to-use yet powerful system for capturing scientific workflows (SWFs). SWFs are a formalization of the ad-hoc process that a scientist may go through to get from raw data to publishable results. Kepler attempts to streamline the workflow creation and execution process so that scientists can design, execute, monitor, re-run, and communicate analytical procedures repeatedly with minimal effort. Kepler is unique in that it seamlessly combines high-level workflow design with execution and runtime interaction, access to local and remote data, and local and remote service invocation. SWFs are superficially similar to business process workflows but have several challenges not present in the business workflow scenario. For example, they often operate on large, complex and heterogeneous data, can be computationally intensive and produce complex derived data products that may be archived for use in reparameterized runs or other workflows. Moreover, unlike business workflows, SWFs are often dataflow-oriented as witnessed by a number of recent academic systems (e.g., DiscoveryNet, Taverna and Triana) and commercial systems (Scitegic/Pipeline-Pilot, Inforsense). In a sense, SWFs are often closer to signal-processing and data streaming applications than they are to control-oriented business workflow applications.
TL;DR: In this paper, an evaluation of the Earth Observing System (EOS) MODIS thermal infrared bands and the status of land surface temperature (LST) version-3 standard products retrieved from Terra MODIS data is presented.
Abstract: This paper presents an evaluation of the Earth Observing System (EOS) Moderate Resolution Imaging Spectroradiometer (MODIS) thermal infrared bands and the status of land surface temperature (LST) version-3 standard products retrieved from Terra MODIS data. The accuracy of daily MODIS LST products has been validated in more than 20 clear-sky cases with in situ measurement data collected in field campaigns in 2000–2002. The MODIS LST accuracy is better than 1°C in the range from −10 to 50°C. Refinements and improvements were made to the new version of MODIS LST product generation executive code. Using both Terra and Aqua MODIS data for LST retrieval improves the quality of the LST product and the diurnal feature in the product due to better temporal, spatial and angular coverage of clear-sky observations.
TL;DR: In this article, solid solutions of tungstate and molybdate scheelites doped with Eu 3+ ion have been synthesized by solid-state reactions.
17 May 2004
TL;DR: It is shown that a large class of composite web services with unbounded input queues can be completely verified using a finite state model checker such as SPIN, and a set of sufficient conditions that guarantee synchronizability and that can be checked statically are given.
Abstract: This paper presents a set of tools and techniques for analyzing interactions of composite web services which are specified in BPEL and communicate through asynchronous XML messages. We model the interactions of composite web services as conversations, the global sequence of messages exchanged by the web services. As opposed to earlier work, our tool-set handles rich data manipulation via XPath expressions. This allows us to verify designs at a more detailed level and check properties about message content. We present a framework where BPEL specifications of web services are translated to an intermediate representation, followed by the translation of the intermediate representation to a verification language. As an intermediate representation we use guarded automata augmented with unbounded queues for incoming messages, where the guards are expressed as XPath expressions. As the target verification language we use Promela, input language of the model checker SPIN. Since SPIN model checker is a finite-state verification tool we can only achieve partial verification by fixing the sizes of the input queues in the translation. We propose the concept of synchronizability to address this problem. We show that if a composite web service is synchronizable, then its conversation set remains same when asynchronous communication is replaced with synchronous communication. We give a set of sufficient conditions that guarantee synchronizability and that can be checked statically. Based on our synchronizability results, we show that a large class of composite web services with unbounded input queues can be completely verified using a finite state model checker such as SPIN.
TL;DR: It appears that the mean dimensions of the large majority of chemically denatured proteins are effectively indistinguishable from themean dimensions of a random-coil ensemble.
Abstract: Spectroscopic studies have identified a number of proteins that appear to retain significant residual structure under even strongly denaturing conditions. Intrinsic viscosity, hydrodynamic radii, and small-angle x-ray scattering studies, in contrast, indicate that the dimensions of most chemically denatured proteins scale with polypeptide length by means of the power-law relationship expected for random-coil behavior. Here we further explore this discrepancy by expanding the length range of characterized denatured-state radii of gyration (RG) and by reexamining proteins that reportedly do not fit the expected dimensional scaling. We find that only 2 of 28 crosslink-free, prosthetic-group-free, chemically denatured polypeptides deviate significantly from a power-law relationship with polymer length. The RG of the remaining 26 polypeptides, which range from 16 to 549 residues, are well fitted (r2 = 0.988) by a power-law relationship with a best-fit exponent, 0.598 ± 0.028, coinciding closely with the 0.588 predicted for an excluded volume random coil. Therefore, it appears that the mean dimensions of the large majority of chemically denatured proteins are effectively indistinguishable from the mean dimensions of a random-coil ensemble.
TL;DR: This article showed that the separability of mental rotation and perspective taking is not dependent on the method by which people are tested and that measures of perspective taking and mental rotation are quite highly correlated.
TL;DR: The preparation of diblock copolypeptides that self-assemble into spherical vesicular assemblies whose size and structure are dictated primarily by the ordered conformations of the polymer segments, in a manner similar to viral capsid assembly is reported.
Abstract: In biology, lipids are well known for their ability to assemble into spherical vesicles. Proteins, in particular virus capsids, can also form regular vesicle-like structures, where the precise folding and stable conformations of many identical subunits directs their self-assembly. Functionality present on these subunits also controls their disassembly within the cellular environment, for example, in response to a pH change. Here, we report the preparation of diblock copolypeptides that self-assemble into spherical vesicular assemblies whose size and structure are dictated primarily by the ordered conformations of the polymer segments, in a manner similar to viral capsid assembly. Furthermore, functionality was incorporated into these molecules to render them susceptible to environmental stimuli, which is desirable for drug-delivery applications. The control of assembly and function exhibited in these systems is a significant advance towards the synthesis of materials that can mimic the precise three-dimensional assembly found in proteins.