212 research outputs found
Disordered mesoscopic systems with interactions: induced two-body ensembles and the Hartree-Fock approach
We introduce a generic approach to study interaction effects in diffusive or
chaotic quantum dots in the Coulomb blockade regime. The randomness of the
single-particle wave functions induces randomness in the two-body interaction
matrix elements. We classify the possible induced two-body ensembles, both in
the presence and absence of spin degrees of freedom. The ensembles depend on
the underlying space-time symmetries as well as on features of the two-body
interaction. Confining ourselves to spinless electrons, we then use the
Hartree-Fock (HF) approximation to calculate HF single-particle energies and HF
wave functions for many realizations of the ensemble. We study the statistical
properties of the resulting one-body HF ensemble for a fixed number of
electrons. In particular, we determine the statistics of the interaction matrix
elements in the HF basis, of the HF single-particle energies (including the HF
gap between the last occupied and the first empty HF level), and of the HF
single-particle wave functions. We also study the addition of electrons, and in
particular the distribution of the distance between successive conductance
peaks and of the conductance peak heights.Comment: 25 pages, 16 figure
Ordered and periodic chaos of the bounded one dimensinal multibarrier potential
Numerical analysis indicates that there exists an unexpected new ordered
chaos for the bounded one-dimensional multibarrier potential. For certain
values of the number of barriers, repeated identical forms (periods) of the
wavepackets result upon passing through the multibarrier potential.Comment: 16 pages, 9 figures, 1 Table. Some former text removed and other
introduce
Discrete charging of metallic grains: Statistics of addition spectra
We analyze the statistics of electrostatic energies (and their differences)
for a quantum dot system composed of a finite number of electron islands
(metallic grains) with random capacitance-inductance matrix , for which the
total charge is discrete, (where is the charge of an electron and
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) 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 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
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
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
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
A global analysis of Y-chromosomal haplotype diversity for 23 STR loci
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
Persistent Place-Making in Prehistory: the Creation, Maintenance, and Transformation of an Epipalaeolithic Landscape
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
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
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