Showing papers by "University of California, Santa Barbara published in 2005"
TL;DR: By applying specific fabrication conditions summarized in the Experimental section and post-production annealing at 150°C, polymer solar cells with power-conversion efficiency approaching 5% were demonstrated.
Abstract: By applying the specific fabrication conditions summarized in the Experimental section and post-production annealing at 150 °C, polymer solar cells with power-conversion efficiency approaching 5 % are demonstrated. These devices exhibit remarkable thermal stability. We attribute the improved performance to changes in the bulk heterojunction material induced by thermal annealing. The improved nanoscale morphology, the increased crystallinity of the semiconducting polymer, and the improved contact to the electron-collecting electrode facilitate charge generation, charge transport to, and charge collection at the electrodes, thereby enhancing the device efficiency by lowering the series resistance of the polymer solar cells.
4,513 citations
TL;DR: It is demonstrated coherent control of a quantum two-level system based on two-electron spin states in a double quantum dot, allowing state preparation, coherent manipulation, and projective readout based on rapid electrical control of the exchange interaction.
Abstract: We demonstrated coherent control of a quantum two-level system based on two-electron spin states in a double quantum dot, allowing state preparation, coherent manipulation, and projective readout. These techniques are based on rapid electrical control of the exchange interaction. Separating and later recombining a singlet spin state provided a measurement of the spin dephasing time, T2*, of E10 nanoseconds, limited by hyperfine interactions with the gallium arsenide host nuclei. Rabi oscillations of two-electron spin states were demonstrated, and spin-echo pulse sequences were used to suppress hyperfine-induced dephasing. Using these quantum control techniques, a coherence time for two-electron spin states exceeding 1 microsecond was observed.
2,789 citations
TL;DR: This chapter addresses the psychological effects of social stigma by reviewing and organizing recent theory and empirical research within an identity threat model of stigma, which posits that situational cues, collective representations of one's stigma status, and personal beliefs and motives shape appraisals of the significance of stigma-relevant situations for well-being.
Abstract: This chapter addresses the psychological effects of social stigma. Stigma directly affects the stigmatized via mechanisms of discrimination, expectancy confirmation, and automatic stereotype activation, and indirectly via threats to personal and social identity. We review and organize recent theory and empirical research within an identity threat model of stigma. This model posits that situational cues, collective representations of one's stigma status, and personal beliefs and motives shape appraisals of the significance of stigma-relevant situations for well-being. Identity threat results when stigma-relevant stressors are appraised as potentially harmful to one's social identity and as exceeding one's coping resources. Identity threat creates involuntary stress responses and motivates attempts at threat reduction through coping strategies. Stress responses and coping efforts affect important outcomes such as self-esteem, academic achievement, and health. Identity threat perspectives help to explain the...
2,680 citations
TL;DR: Magnetoelectric multiferroics combine ferromagnetic magnetization and ferroelectricity in the same phase and have tremendous potential for applications, not only because they possess the properties of both parent phenomena, but also because coupling between ferromagnetism and electric polarization can lead to additional novel effects as discussed by the authors.
Abstract: Magnetoelectric multiferroics combine ferromagnetism (a spontaneous magnetization that can be switched by a magnetic field) and ferroelectricity (a spontaneous electric polarization that can be switched by an electric field) in the same phase They have tremendous potential for applications, not only because they possess the properties of both parent phenomena, but also because coupling between ferromagnetism and ferroelectricity can lead to additional novel effects In their Perspective,
Spaldin and Fiebig
discuss the factors behind the recent resurgence of interest in magnetoelectric multiferroics, describe some exciting results emerging from the current research activities, and point to important challenges and directions for future work
2,523 citations
TL;DR: The authors proposed a framework for the analysis of identity as produced in linguistic interaction, based on the following principles: identity is the product rather than the source of linguis... and identity is generated from linguistic interaction.
Abstract: The article proposes a framework for the analysis of identity as produced in linguistic interaction, based on the following principles: (1) identity is the product rather than the source of linguis...
2,419 citations
TL;DR: It is shown that factor H (HF1), the major inhibitor of the alternative complement pathway, accumulates within drusen and is synthesized by the retinal pigmented epithelium, implicating HF1 function in the pathogenetic mechanisms underlying AMD.
Abstract: Age-related macular degeneration (AMD) is the most frequent cause of irreversible blindness in the elderly in developed countries. Our previous studies implicated activation of complement in the formation of drusen, the hallmark lesion of AMD. Here, we show that factor H (HF1), the major inhibitor of the alternative complement pathway, accumulates within drusen and is synthesized by the retinal pigmented epithelium. Because previous linkage analyses identified chromosome 1q25-32, which harbors the factor H gene (HF1/CFH), as an AMD susceptibility locus, we analyzed HF1 for genetic variation in two independent cohorts comprised of ≈900 AMD cases and 400 matched controls. We found association of eight common HF1 SNPs with AMD; two common missense variants exhibit highly significant associations (I62V, χ2 = 26.1 and P = 3.2 × 10-7 and Y402H, χ2 = 54.4 and P = 1.6 × 10-13). Haplotype analysis reveals that multiple HF1 variants confer elevated or reduced risk of AMD. One common at-risk haplotype is present at a frequency of 50% in AMD cases and 29% in controls [odds ratio (OR) = 2.46, 95% confidence interval (1.95-3.11)]. Homozygotes for this haplotype account for 24% of cases and 8% of controls [OR = 3.51, 95% confidence interval (2.13-5.78)]. Several protective haplotypes are also identified (OR = 0.44-0.55), further implicating HF1 function in the pathogenetic mechanisms underlying AMD. We propose that genetic variation in a regulator of the alternative complement pathway, when combined with a triggering event, such as infection, underlie a major proportion of AMD in the human population.
2,012 citations
TL;DR: The electromagnetic theory of surface-enhanced Raman spectroscopy (SERS), despite its simplicity, can account for all major SERS observations, including: the need for a nanostructured material as the SERS-active system; the observation that some metals form good SERS active systems while others do not; the observed polarization sensitivity shown by nanoparticle aggregates; and the optical behavior of nanostructure materials in the absence of a molecular adsorbate as mentioned in this paper.
Abstract: The electromagnetic theory of surface-enhanced Raman spectroscopy (SERS), despite its simplicity, can account for all major SERS observations, including: the need for a nanostructured material as the SERS-active system; the observation that some metals form good SERS-active systems while others do not; the observation that strongly interacting metal nanoparticles result in very much more effective SERS-active systems; the observed polarization sensitivity shown by nanoparticle aggregates; and the optical behavior of nanostructured metals in the absence of a molecular adsorbate. By extending the ideas inherent in the electromagnetic model one can also understand the seminal features reported for single-molecule SERS, including the puzzling observation that only a few silver ‘particles’ in an ensemble are ‘hot’ (they are appropriately structured nanoparticle clusters) and that for a hot particle, once one is able to observe SERS, adding more adsorbate does not significantly alter the intensity (once the electromagnetic hot spot is occupied, adding adsorbate to other sites on the nanoparticle cluster will not add greatly to the observed intensity). However, the electromagnetic model does not account for all that is learned through SERS. Molecular resonances, charge-transfer transitions and other processes such as ballistic electrons transiently probing the region where the molecule resides and then modulating electronic processes of the metal as a result certainly contribute to the rich information SERS reports; and by virtue of the fact that these contributions will vary from molecule to molecule, they will constitute the most interesting aspects reported by SERS. But, the overall reason why SERS produces such inordinate enhancements is largely an electromagnetic property of nanostructures. Copyright © 2005 John Wiley & Sons, Ltd.
1,644 citations
Emory University1, University of California, Los Angeles2, University of Siena3, California Institute of Technology4, University of Zurich5, Central European University6, University of California, Davis7, Texas A&M University8, University of Oxford9, University of New Mexico10, University of Pennsylvania11, University of California, Santa Barbara12, Harvard University13, California State University, Fullerton14, University of Colorado Denver15
TL;DR: A cross-cultural study of behavior in ultimatum, public goods, and dictator games in a range of small-scale societies exhibiting a wide variety of economic and cultural conditions found the canonical model – based on self-interest – fails in all of the societies studied.
Abstract: Researchers from across the social sciences have found consistent deviations from the predictions of the canonical model of self-interest in hundreds of experiments from around the world. This research, however, cannot determine whether the uniformity re- sults from universal patterns of human behavior or from the limited cultural variation available among the university students used in virtually all prior experimental work. To address this, we undertook a cross-cultural study of behavior in ultimatum, public goods, and dictator games in a range of small-scale societies exhibiting a wide variety of economic and cultural conditions. We found, first, that the canonical model - based on self-interest - fails in all of the societies studied. Second, our data reveal substantially more behavioral vari- ability across social groups than has been found in previous research. Third, group-level differences in economic organization and the structure of social interactions explain a substantial portion of the behavioral variation across societies: the higher the degree of market integration and the higher the payoffs to cooperation in everyday life, the greater the level of prosociality expressed in experimental games. Fourth, the available individual-level economic and demographic variables do not consistently explain game behavior, either within or across groups. Fifth, in many cases experimental play appears to reflect the common interactional patterns of everyday life.
1,589 citations
TL;DR: Pd-functionalized nanostructures exhibited a dramatic improvement in sensitivity toward oxygen and hydrogen due to the enhanced catalytic dissociation of the molecular adsorbate on the Pd nanoparticle surfaces and the subsequent diffusion of the resultant atomic species to the oxide surface.
Abstract: The sensing ability of individual SnO2 nanowires and nanobelts configured as gas sensors was measured before and after functionalization with Pd catalyst particles. In situ deposition of Pd in the same reaction chamber in which the sensing measurements were carried out ensured that the observed modification in behavior was due to the Pd functionalization rather than the variation in properties from one nanowire to another. Changes in the conductance in the early stages of metal deposition (i.e., before metal percolation) indicated that the Pd nanoparticles on the nanowire surface created Schottky barrier-type junctions resulting in the formation of electron depletion regions within the nanowire, constricting the effective conduction channel and reducing the conductance. Pd-functionalized nanostructures exhibited a dramatic improvement in sensitivity toward oxygen and hydrogen due to the enhanced catalytic dissociation of the molecular adsorbate on the Pd nanoparticle surfaces and the subsequent diffusion ...
1,307 citations
TL;DR: In this paper, the coupling between the ferroelectric and magnetic order parameters in the magnetoelectric multiferroic was analyzed using density functional theory within the local spin density approximation (LSDA) and the $\mathrm{LSDA}+\mathm{U}$ method.
Abstract: We analyze the coupling between the ferroelectric and magnetic order parameters in the magnetoelectric multiferroic $\mathrm{Bi}\mathrm{Fe}{\mathrm{O}}_{3}$ using density functional theory within the local spin density approximation (LSDA) and the $\mathrm{LSDA}+\mathrm{U}$ method. We show that weak ferromagnetism of the Dzyaloshinskii-Moriya type occurs in this material, and we analyze the coupling between the resulting magnetization and the structural distortions. We explore the possibility of electric-field-induced magnetization reversal and show that, although it is unlikely to be realized in $\mathrm{Bi}\mathrm{Fe}{\mathrm{O}}_{3}$, it is not in general impossible. Finally, we outline the conditions that must be fulfilled to achieve switching of the magnetization using an electric field.
1,242 citations
TL;DR: Polymer synthesis methods now being developed will yield well-defined synthetic macromolecules that are capable of mimicking many of the features of proteins and other natural materials.
Abstract: Several recent conceptual advances, which take advantage of the design criteria and practical techniques of molecular-level control in organic chemistry, allow preparation of well-defined polymers and nanostructured materials Two trends are clear: the realization that synthesis of complex macromolecules poses major challenges and opportunities and the expectation that such materials will exhibit distinctive properties and functions Polymer synthesis methods now being developed will yield well-defined synthetic macromolecules that are capable of mimicking many of the features of proteins (for example, three-dimensional folded structure) and other natural materials These macromolecules have far-reaching potential for the study of molecular-level behavior at interfaces, in thin films, and in solution, while also enabling the development of encapsulation, drug-delivery, and nanoscale-patterning technologies
TL;DR: CA-TIMS as discussed by the authors uses high-temperature treatment to anneal zircon lattice radiation damage from natural alpha, alpha recoil, and spontaneous fission processes; this annealing eliminates elemental and isotopic leaching effects that have limited earlier efforts at chemical leaching or multi-step step-wise dissolution or partial dissolution analysis (PDA)
TL;DR: It is shown that approximately 50% of the variation in community composition is explained by both environmental and spatial variables, and metacommunity characteristics such as dispersal type, habitat type and spatial scale predicted part of the detected variation in metacomunity structure.
Abstract: The processes controlling the abundances of species across multiple sites form the cornerstone of modern ecology. In these metacommunities, the relative importance of local environmental and regional spatial processes is currently hotly debated, especially in terms of the validity of neutral model. I collected 158 published data sets with information on community structure, environmental and spatial variables. I showed that approximately 50% of the variation in community composition is explained by both environmental and spatial variables. The majority of the data sets were structured by species-sorting dynamics (SS), followed by a combination of SS and mass-effect dynamics. While neutral processes were the only structuring process in 8% of the collected natural communities, disregarding neutral dispersal processes would result in missing important patterns in 37% of the studied communities. Moreover, metacommunity characteristics such as dispersal type, habitat type and spatial scale predicted part of the detected variation in metacommunity structure.
TL;DR: In this paper, the authors examine four practices through which a second speaker can index the independence of an agreeing assessment from that of a first speaker, and in this way can qualify the agreement.
Abstract: Within the general framework of agreement on a state of affairs, the matter of the terms of agreement can remain: determining whose view is the more significant or more authoritative with respect to the matter at hand. In this paper we focus on this issue as it is played out in assessment sequences. We examine four practices through which a second speaker can index the independence of an agreeing assessment from that of a first speaker, and in this way can qualify the agreement. We argue that these practices reduce the responsiveness of the second assessment to the first; in this way they resist any claim to epistemic authority that may be indexed by the first speaker in “going first” in assessing some state of affairs.
TL;DR: Mezic and Banaszuk as mentioned in this paper applied spectral properties of the linear Koopman operator associated with the asymptotic dynamics on the attractor of a high-dimensional dynamical system to obtain a decomposition of the process.
Abstract: In this paper we discuss two issues related to model reduction of deterministic or stochastic processes. The first is the relationship of the spectral properties of the dynamics on the attractor of the original, high-dimensional dynamical system with the properties and possibilities for model reduction. We review some elements of the spectral theory of dynamical systems. We apply this theory to obtain a decomposition of the process that utilizes spectral properties of the linear Koopman operator associated with the asymptotic dynamics on the attractor. This allows us to extract the almost periodic part of the evolving process. The remainder of the process has continuous spectrum. The second topic we discuss is that of model validation, where the original, possibly high-dimensional dynamics and the dynamics of the reduced model – that can be deterministic or stochastic – are compared in some norm. Using the “statistical Takens theorem” proven in (Mezic, I. and Banaszuk, A. Physica D, 2004) we argue that comparison of average energy contained in the finite-dimensional projection is one in the hierarchy of functionals of the field that need to be checked in order to assess the accuracy of the projection.
TL;DR: In this paper, the magnitude and distance of edge influence are a direct function of the contrast in structure and composition between adjacent communities on either side of the edge, and local factors such as climate, edge characteristics, stand attributes, and biotic factors affect patch contrast.
Abstract: Although forest edges have been studied extensively as an important consequence of fragmenta- tion, a unifying theory of edge influence has yet to be developed. Our objective was to take steps toward the development of such a theory by (1) synthesizing the current knowledge of patterns of forest structure and composition at anthropogenically created forest edges, (2) developing hypotheses about the magnitude and distance of edge influence that consider the ecological processes influencing these patterns, and (3) identifying needs for future research. We compiled data from 44 published studies on edge influence on forest structure and composition in boreal, temperate, and tropical forests. Abiotic and biotic gradients near created forest edges generate a set of primary responses to edge creation. Indirect effects from these primary responses and the original edge gradient perpetuate edge influence, leading to secondary responses. Further changes in veg- etation affect the edge environment, resulting in ongoing edge dynamics. We suggest that the magnitude and distance of edge influence are a direct function of the contrast in structure and composition between adjacent communities on either side of the edge. Local factors such as climate, edge characteristics, stand attributes, and biotic factors affect patch contrast. Regional factors define the context within which to assess the ecological significance of edge influence (the degree to which the edge habitat differs from interior forest habitat). Our hypotheses will help predict edge influence on structure and composition in forested ecosystems, an important consideration for conservation. For future research on forest edges in fragmented landscapes, we encourage the testing of our hypotheses, the use of standardized methodology, complete descriptions of study sites, studies on other types of edges, synthesis of edge influence on different components of the ecosystem, and investigations of edges in a landscape context.
TL;DR: In this paper, the ground-state structural and electronic properties of ferroelectric are calculated using density functional theory within the local spin-density approximation (LSDA) and the $\mathrm{LSDA}+U$ method.
Abstract: The ground-state structural and electronic properties of ferroelectric $\mathrm{Bi}\mathrm{Fe}{\mathrm{O}}_{3}$ are calculated using density functional theory within the local spin-density approximation (LSDA) and the $\mathrm{LSDA}+U$ method. The crystal structure is computed to be rhombohedral with space group $R3c$, and the electronic structure is found to be insulating and antiferromagnetic, both in excellent agreement with available experiments. A large ferroelectric polarization of $90--100\phantom{\rule{0.3em}{0ex}}\ensuremath{\mu}\mathrm{C}∕{\mathrm{cm}}^{2}$ is predicted, consistent with the large atomic displacements in the ferroelectric phase and with recent experimental reports, but differing by an order of magnitude from early experiments. One possible explanation is that the latter may have suffered from large leakage currents. However, both past and contemporary measurements are shown to be consistent with the modern theory of polarization, suggesting that the range of reported polarizations may instead correspond to distinct switching paths in structural space. Modern measurements on well-characterized bulk samples are required to confirm this interpretation.
TL;DR: In this article, a series of theorems relating log-concavity and/or logconvexity of probability density functions, distribution functions, reliability functions, and their integrals are presented.
Abstract: In many applications, assumptions about the log-concavity of a probability distribution allow just enough special structure to yield a workable theory. This paper catalogs a series of theorems relating log-concavity and/or log-convexity of probability density functions, distribution functions, reliability functions, and their integrals. We list a large number of commonly-used probability distributions and report the log-concavity or log-convexity of their density functions and their integrals. We also discuss a variety of applications of log-concavity that have appeared in the literature.
TL;DR: In this article, a ZnO nanowire-based dye-sensitized solar cell was proposed to provide a direct conduction path for electrons between the point of photogeneration and the conducting substrate and may offer improved electron transport compared to films of sintered nanoparticles.
Abstract: We describe the design and performance of a ZnO nanowire-based dye-sensitized solar cell. ZnO nanowires with a branched structure were employed as the wide-band-gap semiconductor to construct dye-sensitized solar cells which exhibit energy conversion efficiencies of 0.5% with internal quantum efficiencies of 70%. The nanowires provide a direct conduction path for electrons between the point of photogeneration and the conducting substrate and may offer improved electron transport compared to films of sintered nanoparticles. The devices have light harvesting efficiencies under 10%, indicating that current densities and efficiencies can be improved by an order of magnitude by increasing the nanowire surface area.
TL;DR: The structural properties of biosilica observed in the hexactinellid sponge Euplectella sp.
Abstract: Structural materials in nature exhibit remarkable designs with building blocks, often hierarchically arranged from the nanometer to the macroscopic length scales. We report on the structural properties of biosilica observed in the hexactinellid sponge Euplectella sp. Consolidated, nanometer-scaled silica spheres are arranged in well-defined microscopic concentric rings glued together by organic matrix to form laminated spicules. The assembly of these spicules into bundles, effected by the laminated silica-based cement, results in the formation of a macroscopic cylindrical square-lattice cagelike structure reinforced by diagonal ridges. The ensuing design overcomes the brittleness of its constituent material, glass, and shows outstanding mechanical rigidity and stability. The mechanical benefits of each of seven identified hierarchical levels and their comparison with common mechanical engineering strategies are discussed.
TL;DR: It is found that the magnitude of pollen limitation observed in natural populations depends on both historical constraints and contemporary ecological factors.
Abstract: ▪ Abstract Quantifying the extent to which seed production is limited by the availability of pollen has been an area of intensive empirical study over the past few decades. Whereas theory predicts that pollen augmentation should not increase seed production, numerous empirical studies report significant and strong pollen limitation. Here, we use a variety of approaches to examine the correlates of pollen limitation in an effort to understand its occurrence and importance in plant evolutionary ecology. In particular, we examine the role of recent ecological perturbations in influencing pollen limitation and discuss the relation between pollen limitation and plant traits. We find that the magnitude of pollen limitation observed in natural populations depends on both historical constraints and contemporary ecological factors.
TL;DR: It is shown that an array of amyloids molecules, including amyloid-beta(1-40), alpha-synuclein, ABri, ADan, serum amylid A, and amylin undergo supramolecular conformational change and in reconstituted membranes, they form morphologically compatible ion-channel-like structures and elicit single ion- channel currents.
Abstract: Protein conformational diseases, including Alzheimer's, Huntington's, and Parkinson's diseases, result from protein misfolding, giving a distinct fibrillar feature termed amyloid. Recent studies show that only the globular (not fibrillar) conformation of amyloid proteins is sufficient to induce cellular pathophysiology. However, the 3D structural conformations of these globular structures, a key missing link in designing effective prevention and treatment, remain undefined as of yet. By using atomic force microscopy, circular dichroism, gel electrophoresis, and electrophysiological recordings, we show here that an array of amyloid molecules, including amyloid-β(1–40), α-synuclein, ABri, ADan, serum amyloid A, and amylin undergo supramolecular conformational change. In reconstituted membranes, they form morphologically compatible ion-channel-like structures and elicit single ion-channel currents. These ion channels would destabilize cellular ionic homeostasis and hence induce cell pathophysiology and degeneration in amyloid diseases.
TL;DR: Compared to an earlier chlorophyll-based approach, carbonbased values are considerably higher in tropical oceans, show greater seasonality at middle and high latitudes, and illustrate important differences in the formation and demise of regional algal blooms.
Abstract: carbon(C)andchlorophyll(Chl)biomassandshowthatderivedChl:Cratioscloselyfollow anticipated physiological dependencies on light, nutrients, and temperature. With this new information, global estimates of phytoplankton growth rates (m) and carbon-based NPP are made for the first time. Compared to an earlier chlorophyll-based approach, our carbonbased values are considerably higher in tropical oceans, show greater seasonality at middle and high latitudes, and illustrate important differences in the formation and demise of regional algal blooms. This fusion of emerging concepts from the phycological and remote sensing disciplines has the potential to fundamentally change how we model and observe carbon cycling in the global oceans.
University of Groningen1, National Institute of Water and Atmospheric Research2, Moss Landing Marine Laboratories3, University of California, San Diego4, University of Tokyo5, Alfred Wegener Institute for Polar and Marine Research6, University of East Anglia7, Duke University8, University of California, Santa Barbara9, Woods Hole Oceanographic Institution10, University of Western Brittany11, Leibniz Institute for Neurobiology12, Rutgers University13, Hong Kong University of Science and Technology14, University of Miami15, Université libre de Bruxelles16, Laval University17, University of British Columbia18, Central Research Institute of Electric Power Industry19, National Institute for Environmental Studies20, University of Western Australia21, Fisheries and Oceans Canada22
TL;DR: In this paper, a comparison of eight iron experiments shows that maximum Chl a, the maximum DIC removal, and the overall DIC/Fe efficiency all scale inversely with depth of the wind mixed layer (WML) defining the light environment.
Abstract: Comparison of eight iron experiments shows that maximum Chl a, the maximum DIC removal, and the overall DIC/Fe efficiency all scale inversely with depth of the wind mixed layer (WML) defining the light environment. Moreover, lateral patch dilution, sea surface irradiance, temperature, and grazing play additional roles. The Southern Ocean experiments were most influenced by very deep WMLs. In contrast, light conditions were most favorable during SEEDS and SERIES as well as during IronEx-2. The two extreme experiments, EisenEx and SEEDS, can be linked via EisenEx bottle incubations with shallower simulated WML depth. Large diatoms always benefit the most from Fe addition, where a remarkably small group of thriving diatom species is dominated by universal response of Pseudo-nitzschia spp. Significant response of these moderate (10–30 μm), medium (30–60 μm), and large (>60 μm) diatoms is consistent with growth physiology determined for single species in natural seawater. The minimum level of “dissolved” Fe (filtrate < 0.2 μm) maintained during an experiment determines the dominant diatom size class. However, this is further complicated by continuous transfer of original truly dissolved reduced Fe(II) into the colloidal pool, which may constitute some 75% of the “dissolved” pool. Depth integration of carbon inventory changes partly compensates the adverse effects of a deep WML due to its greater integration depths, decreasing the differences in responses between the eight experiments. About half of depth-integrated overall primary productivity is reflected in a decrease of DIC. The overall C/Fe efficiency of DIC uptake is DIC/Fe ∼ 5600 for all eight experiments. The increase of particulate organic carbon is about a quarter of the primary production, suggesting food web losses for the other three quarters. Replenishment of DIC by air/sea exchange tends to be a minor few percent of primary CO2 fixation but will continue well after observations have stopped. Export of carbon into deeper waters is difficult to assess and is until now firmly proven and quite modest in only two experiments.
TL;DR: In this paper, an integrated strategy of experiment, intuitive arguments based on crystallography, and simulation may lead most rapidly to the development of new thermal barrier coatings (TBCs) materials.
TL;DR: Results from four different kinds of category-learning tasks provide strong evidence that human category learning is mediated by multiple, qualitatively distinct systems.
Abstract: Much recent evidence suggests some dramatic differences in the way people learn perceptual categories, depending on exactly how the categories were constructed. Four different kinds of category-learning tasks are currently popular-rule-based tasks, information-integration tasks, prototype distortion tasks, and the weather prediction task. The cognitive, neuropsychological, and neuroimaging results obtained using these four tasks are qualitatively different. Success in rule-based (explicit reasoning) tasks depends on frontal-striatal circuits and requires working memory and executive attention. Success in information-integration tasks requires a form of procedural learning and is sensitive to the nature and timing of feedback. Prototype distortion tasks induce perceptual (visual cortical) learning. A variety of different strategies can lead to success in the weather prediction task. Collectively, results from these four tasks provide strong evidence that human category learning is mediated by multiple, qualitatively distinct systems.
TL;DR: Evidence is found that bone consists of mineralized collagen fibrils and a non-fibrillar organic matrix, which acts as a ‘glue’ that holds the mineralized fibril together, and it is believed that this glue may resist the separation of mineralization of bone composite.
Abstract: Properties of the organic matrix of bone as well as its function in the microstructure could be the key to the remarkable mechanical properties of bone. Previously, it was found that on the molecular level, calcium-mediated sacrificial bonds increased stiffness and enhanced energy dissipation in bone constituent molecules. Here we present evidence for how this sacrificial bond and hidden length mechanism contributes to the mechanical properties of the bone composite, by investigating the nanoscale arrangement of the bone constituents and their interactions. We find evidence that bone consists of mineralized collagen fibrils and a non-fibrillar organic matrix, which acts as a 'glue' that holds the mineralized fibrils together. We believe that this glue may resist the separation of mineralized collagen fibrils. As in the case of the sacrificial bonds in single molecules, the effectiveness of this mechanism increases with the presence of Ca2+ ions.
TL;DR: Ultrasound, which is routinely used for diagnostic imaging applications, is now being adopted in various drug delivery and other therapeutic applications, and the principles and current status are reviewed.
Abstract: Ultrasound, which is routinely used for diagnostic imaging applications, is now being adopted in various drug delivery and other therapeutic applications. Ultrasound has been shown to facilitate the delivery of drugs across the skin, promote gene therapy to targeted tissues, deliver chemotherapeutic drugs into tumours and deliver thrombolytic drugs into blood clots. In addition, ultrasound has also been shown to facilitate the healing of wounds and bone fractures. This article reviews the principles and current status of ultrasound-based treatments.
TL;DR: An expanding body of work is highlighted that examines how plasticity can affect all levels of ecological organization through effects on demographic parameters, direct and indirect species interactions, such as competition, predation, and coexistence, and ultimately carbon and nutrient cycles.
Abstract: Phenotypic plasticity is widespread in nature, and often involves ecologically relevant behavioral, physiological, morphological and life-historical traits. As a result, plasticity alters numerous interactions between organisms and their abiotic and biotic environments. Although much work on plasticity has focused on its patterns of expression and evolution, researchers are increasingly interested in understanding how plasticity can affect ecological patterns and processes at various levels. Here, we highlight an expanding body of work that examines how plasticity can affect all levels of ecological organization through effects on demographic parameters, direct and indirect species interactions, such as competition, predation, and coexistence, and ultimately carbon and nutrient cycles.