172 research outputs found

    Discrete charging of metallic grains: Statistics of addition spectra

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    We analyze the statistics of electrostatic energies (and their differences) for a quantum dot system composed of a finite number KK of electron islands (metallic grains) with random capacitance-inductance matrix CC, for which the total charge is discrete, Q=NeQ=Ne (where ee is the charge of an electron and NN is an integer). The analysis is based on a generalized charging model, where the electrons are distributed among the grains such that the electrostatic energy E(N) is minimal. Its second difference (inverse compressibility) χN=E(N+1)−2E(N)+E(N−1)\chi_{N}=E(N+1)-2 E(N)+E(N-1) represents the spacing between adjacent Coulomb blockade peaks appearing when the conductance of the quantum dot is plotted against gate voltage. The statistics of this quantity has been the focus of experimental and theoretical investigations during the last two decades. We provide an algorithm for calculating the distribution function corresponding to χN\chi_{N} and show that this function is piecewise polynomial.Comment: 21 pages, no figures, mathematical nomenclature (except for Abstract and Introduction

    On Renyi entropies characterizing the shape and the extension of the phase space representation of quantum wave functions in disordered systems

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    We discuss some properties of the generalized entropies, called Renyi entropies and their application to the case of continuous distributions. In particular it is shown that these measures of complexity can be divergent, however, their differences are free from these divergences thus enabling them to be good candidates for the description of the extension and the shape of continuous distributions. We apply this formalism to the projection of wave functions onto the coherent state basis, i.e. to the Husimi representation. We also show how the localization properties of the Husimi distribution on average can be reconstructed from its marginal distributions that are calculated in position and momentum space in the case when the phase space has no structure, i.e. no classical limit can be defined. Numerical simulations on a one dimensional disordered system corroborate our expectations.Comment: 8 pages with 2 embedded eps figures, RevTex4, AmsMath included, submitted to PR

    Functional investigation of the coronary artery disease gene SVEP1

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    A missense variant of the sushi, von Willebrand factor type A, EGF and pentraxin domain containing protein 1 (SVEP1) is genome-wide significantly associated with coronary artery disease. The mechanisms how SVEP1 impacts atherosclerosis are not known. We found endothelial cells (EC) and vascular smooth muscle cells to represent the major cellular source of SVEP1 in plaques. Plaques were larger in atherosclerosis-prone Svep1 haploinsufficient (ApoE^{−/−}Svep1^{+/−}) compared to Svep1 wild-type mice (ApoE^{−/−}Svep1^{+/+}) and ApoE^{−/−}Svep1^{+/−} mice displayed elevated plaque neutrophil, Ly6C^{high} monocyte, and macrophage numbers. We assessed how leukocytes accumulated more inside plaques in ApoE^{−/−}Svep1^{+/−} mice and found enhanced leukocyte recruitment from blood into plaques. In vitro, we examined how SVEP1 deficiency promotes leukocyte recruitment and found elevated expression of the leukocyte attractant chemokine (C-X-C motif) ligand 1 (CXCL1) in EC after incubation with missense compared to wild-type SVEP1. Increasing wild-type SVEP1 levels silenced endothelial CXCL1 release. In line, plasma Cxcl1 levels were elevated in ApoE^{−/−}Svep1^{+/−} mice. Our studies reveal an atheroprotective role of SVEP1. Deficiency of wild-type Svep1 increased endothelial CXCL1 expression leading to enhanced recruitment of proinflammatory leukocytes from blood to plaque. Consequently, elevated vascular inflammation resulted in enhanced plaque progression in Svep1 deficiency

    Association of the coronary artery disease risk gene GUCY1A3 with ischaemic events after coronary intervention

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    Aim: A common genetic variant at the GUCY1A3 coronary artery disease locus has been shown to influence platelet aggregation. The risk of ischaemic events including stent thrombosis varies with the efficacy of aspirin to inhibit platelet reactivity. This study sought to investigate whether homozygous GUCY1A3 (rs7692387) risk allele carriers display higher on-aspirin platelet reactivity and risk of ischaemic events early after coronary intervention. Methods and results: The association of GUCY1A3 genotype and on-aspirin platelet reactivity was analysed in the genetics substudy of the ISAR-ASPI registry (n = 1678) using impedance aggregometry. The clinical outcome cardiovascular death or stent thrombosis within 30 days after stenting was investigated in a meta-analysis of substudies of the ISAR-ASPI registry, the PLATO trial (n = 3236), and the Utrecht Coronary Biobank (n = 1003) comprising a total 5917 patients. Homozygous GUCY1A3 risk allele carriers (GG) displayed increased on-aspirin platelet reactivity compared with non-risk allele (AA/AG) carriers [150 (interquartile range 91–209) vs. 134 (85–194) AU⋅min, P 203 AU⋅min; 29.5 vs. 24.2%, P = 0.02). Homozygous risk allele carriers were also at higher risk for cardiovascular death or stent thrombosis (hazard ratio 1.70, 95% confidence interval 1.08–2.68; P = 0.02). Bleeding risk was not altered. Conclusion: We conclude that homozygous GUCY1A3 risk allele carriers are at increased risk of cardiovascular death or stent thrombosis within 30 days after coronary stenting, likely due to higher on-aspirin platelet reactivity. Whether GUCY1A3 genotype helps to tailor antiplatelet treatment remains to be investigated

    Persistent Place-Making in Prehistory: the Creation, Maintenance, and Transformation of an Epipalaeolithic Landscape

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    Most archaeological projects today integrate, at least to some degree, how past people engaged with their surroundings, including both how they strategized resource use, organized technological production, or scheduled movements within a physical environment, as well as how they constructed cosmologies around or created symbolic connections to places in the landscape. However, there are a multitude of ways in which archaeologists approach the creation, maintenance, and transformation of human-landscape interrelationships. This paper explores some of these approaches for reconstructing the Epipalaeolithic (ca. 23,000–11,500 years BP) landscape of Southwest Asia, using macro- and microscale geoarchaeological approaches to examine how everyday practices leave traces of human-landscape interactions in northern and eastern Jordan. The case studies presented here demonstrate that these Epipalaeolithic groups engaged in complex and far-reaching social landscapes. Examination of the Early and Middle Epipalaeolithic (EP) highlights that the notion of “Neolithization” is somewhat misleading as many of the features we use to define this transition were already well-established patterns of behavior by the Neolithic. Instead, these features and practices were enacted within a hunter-gatherer world and worldview

    The Long-Term Evolution of Social Organization

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    This chapter outlines how the ‘innovation innovation’ transformed the world of our distant ancestors into that in which we live today. It focuses on the relationship between people and the material world, as it is the material world that has been most drastically, and measurably, transformed over the last several tens of thousands of years. In view of what we know about such distant periods, and in view of the space allot-ted to us here, it will not surprise the reader that we do so in the form of a narrative that is only partly underpinned by substantive data. We emphasize this because we do not want to hide from the reader the speculative nature of the story that follows. Yet we firmly believe that, in very general terms, this scenario is correct, and that further research will vindicate us.We first give examples of the kinds of abstractions, and the hierarchy of conceptual dimensions necessary for prehistoric human beings and their ancestors, to conquer matter, i.e. to conceptually understand, transmit and apply the operations needed to master the making of a range of objects made out of stone, bone, wood, clay and other materials. Some of the abstractions that had to be conceived in this domain re-semble those that Read et al. (http://www.escholarship.org/uc/item/2798j162) refer to, while others apply to this domain alone, and had to be truly ‘invented’. It is then argued that such ‘identification of conceptual dimensions’ is a process that underlies all human activity, and we look a little closer at how that process relates to invention and innovation.Lastly, we shift our attention to the role of innovation, information processing and communication in the emergence of social institutions, and in the structural transformation of human societies as they grow in size and complexity. In particular, we look at the role that problem solving and invention play in creating more and more complex societies, encompassing increasing numbers of people, more and more diverse institutions, and an – ultimately seemingly all-encompassing – appropriation of the natural environment. To illustrate this development we will focus on the origins and growth of urban systems

    A global analysis of Y-chromosomal haplotype diversity for 23 STR loci

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    In a worldwide collaborative effort, 19,630 Y-chromosomes were sampled from 129 different populations in 51 countries. These chromosomes were typed for 23 short-tandem repeat (STR) loci (DYS19, DYS389I, DYS389II, DYS390, DYS391, DYS392, DYS393, DYS385ab, DYS437, DYS438, DYS439, DYS448, DYS456, DYS458, DYS635, GATAH4, DYS481, DYS533, DYS549, DYS570, DYS576, and DYS643) and using the PowerPlex Y23 System (PPY23, Promega Corporation, Madison, WI). Locus-specific allelic spectra of these markers were determined and a consistently high level of allelic diversity was observed. A considerable number of null, duplicate and off-ladder alleles were revealed. Standard single-locus and haplotype-based parameters were calculated and compared between subsets of Y-STR markers established for forensic casework. The PPY23 marker set provides substantially stronger discriminatory power than other available kits but at the same time reveals the same general patterns of population structure as other marker sets. A strong correlation was observed between the number of Y-STRs included in a marker set and some of the forensic parameters under study. Interestingly a weak but consistent trend toward smaller genetic distances resulting from larger numbers of markers became apparent.Peer reviewe

    Archaeological Ethnography, Heritage Management, and Community Archaeology: A Pragmatic Approach from Crete

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    This article examines the introduction of archaeological ethnography as an approach to establish positioned research and bring context-specific and reflexive considerations into community archaeology projects. It considers recent cri-tiques of heritage management in archaeology and the role of archaeologists as experts in it, contending that smaller and less prominent sites exist in different contexts and pose different problems than large-scale projects usually addressed in the literature. We describe how the ‘Three Peak Sanctuaries of Central Crete’ project, investigating prehistoric Minoan ritual sites, involves communities and stakeholders and what demands the latter pose on experts in the field. Archae-ological work is always already implicated in local development projects which create and reproduce power hierarchies. It is therefore important that archaeol-ogists maintain their critical distance from official heritage discourses, as they are materialized in development programmes, while at the same time engaging with local expectations and power struggles; they also have to critically address and position their own assumptions. We use examples from our community archae-ology project to propose that these goals can be reached through archaeological ethnographic fieldwork that should precede any archaeological project to inform its methodological decisions, engage stakeholders, and collaboratively shape heritage management strategies
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