45,163 research outputs found

    Entanglement entropy with localized and extended interface defects

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    The quantum Ising chain of length, L, which is separated into two parts by localized or extended defects is considered at the critical point where scaling of the interface magnetization is non-universal. We measure the entanglement entropy between the two halves of the system in equilibrium, as well as after a quench, when the interaction at the interface is changed for time t>0. For the localized defect the increase of the entropy with log(L) or with log(t) involves the same effective central charge, which is a continuous function of the strength of the defect. On the contrary for the extended defect the equilibrium entropy is saturated, but the non-equilibrium entropy has a logarithmic time-dependence the prefactor of which depends on the strength of the defect.Comment: 9 pages, 6 figure

    Semiclassical Time Evolution of the Holes from Luttinger Hamiltonian

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    We study the semi-classical motion of holes by exact numerical solution of the Luttinger model. The trajectories obtained for the heavy and light holes agree well with the higher order corrections to the abelian and the non-abelian adiabatic theories in Ref. [1] [S. Murakami et al., Science 301, 1378(2003)], respectively. It is found that the hole trajectories contain rapid oscillations reminiscent of the "Zitterbewegung" of relativistic electrons. We also comment on the non-conservation of helicity of the light holes.Comment: 4 pages, 5 fugure

    Combining Genome Wide Association Studies and Differential Gene Expression Data Analyses Identifies Candidate Genes Affecting Mastitis Caused by Two Different Pathogens in the Dairy Cow

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    Mastitis is a costly disease which hampers the dairy industry. Inflammation of the mammary gland is commonly caused by bacterial infection, mainly Escherichia coli, Streptococcus uberis and Staphylococcus aureus. As more bacteria become multi-drug resistant, one potential approach to reduce the disease incidence rate is to breed selectively for the most appropriate and potentially protective innate immune response. The genetic contribution to effective disease resistance is, however, difficult to identify due to the complex interactions that occur. In the present study two published datasets were searched for common differentially expressed genes (DEGs) with similar changes in expression in mammary tissue following intra-mammary challenge with either E. coli or S. uberis. Additionally, the results of seven published genome-wide association studies (GWAS) on different dairy cow populations were used to compile a list of SNPs associated with somatic cell count. All genes located within 2 Mbp of significant SNPs were retrieved from the Ensembl database, based on the UMD3.1 assembly. A final list of 48 candidate genes with a role in the innate immune response identified from both the DEG and GWAS studies was further analyzed using Ingenuity Pathway Analysis. The main signalling pathways highlighted in the response of the bovine mammary gland to both bacterial infections were 1) granulocyte adhesion and diapedesis, 2) ephrin receptor signalling, 3) RhoA signalling and 4) LPS/IL1 mediated inhibition of RXR function. These pathways comprised a network regulating the activity of leukocytes, especially neutrophils, during mammary gland inflammation. The timely and properly controlled movement of leukocytes to infection loci seems particularly important in achieving a good balance between pathogen elimination and excessive tissue damage. These results suggest that polymorphisms in key genes in these pathways such as SELP, SELL, BCAR1, ACTR3, CXCL2, CXCL6, CXCL8 and FABP may influence the ability of dairy cows to resist mastitis

    Product Measure Steady States of Generalized Zero Range Processes

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    We establish necessary and sufficient conditions for the existence of factorizable steady states of the Generalized Zero Range Process. This process allows transitions from a site ii to a site i+qi+q involving multiple particles with rates depending on the content of the site ii, the direction qq of movement, and the number of particles moving. We also show the sufficiency of a similar condition for the continuous time Mass Transport Process, where the mass at each site and the amount transferred in each transition are continuous variables; we conjecture that this is also a necessary condition.Comment: 9 pages, LaTeX with IOP style files. v2 has minor corrections; v3 has been rewritten for greater clarit

    Flavor violating decays of the Higgs bosons in the THDM-III

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    We calculate the branching ratios for the decays of neutral Higgs bosons (h0,H0,A0h^{0},H^{0},A^{0}) into pairs of fermions, including flavor violating processes, in the context of the General Two Higgs Doublet Model III.Comment: 23 pages, 10 figures, 6 tables. Text clarifying equations and references added, typos correction

    New e-Learning system architecture based on knowledge engineering technology

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    The paper focuses on the field of research on next generational e-Learning facility, in which knowledge-enhanced systems are the most important candidates. In the paper, a reference architecture based on the technologies of knowledge engineering is proposed, which has following three intrinsic characteristics, first, education ontologies are used to facilitate the integration of static learning resource and dynamic learning resource, second, based on semantic-enriched relationships between Learning Objects (LOs), it provides more advanced features for sharing, reusing and repurposing of LOs, third, with the concept of knowledge object, which is extended from LO, an implementing mechanism for knowledge extraction and knowledge evolution in e-Learning facilities is provided. With this reference architecture, a prototype system called FekLoma (Flexible Extensive Knowledge Learning Object Management Architecture) has been realized, and testing on it is carrying out

    Measurement of the c-axis optical reflectance of AFe2_2As2_2 (A=Ba, Sr) single crystals: Evidence of different mechanisms for the formation of two energy gaps

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    We present the c-axis optical reflectance measurement on single crystals of BaFe2_2As2_2 and SrFe2_2As2_2, the parent compounds of FeAs based superconductors. Different from the ab-plane optical response where two distinct energy gaps were observed in the SDW state, only the smaller energy gap could be seen clearly for \textbf{E}\parallelc-axis. The very pronounced energy gap structure seen at a higher energy scale for \textbf{E}\parallelab-plane is almost invisible. We propose a novel picture for the band structure evolution across the SDW transition and suggest different driving mechanisms for the formation of the two energy gaps.Comment: 4 page

    Quantified Derandomization of Linear Threshold Circuits

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    One of the prominent current challenges in complexity theory is the attempt to prove lower bounds for TC0TC^0, the class of constant-depth, polynomial-size circuits with majority gates. Relying on the results of Williams (2013), an appealing approach to prove such lower bounds is to construct a non-trivial derandomization algorithm for TC0TC^0. In this work we take a first step towards the latter goal, by proving the first positive results regarding the derandomization of TC0TC^0 circuits of depth d>2d>2. Our first main result is a quantified derandomization algorithm for TC0TC^0 circuits with a super-linear number of wires. Specifically, we construct an algorithm that gets as input a TC0TC^0 circuit CC over nn input bits with depth dd and n1+exp(d)n^{1+\exp(-d)} wires, runs in almost-polynomial-time, and distinguishes between the case that CC rejects at most 2n11/5d2^{n^{1-1/5d}} inputs and the case that CC accepts at most 2n11/5d2^{n^{1-1/5d}} inputs. In fact, our algorithm works even when the circuit CC is a linear threshold circuit, rather than just a TC0TC^0 circuit (i.e., CC is a circuit with linear threshold gates, which are stronger than majority gates). Our second main result is that even a modest improvement of our quantified derandomization algorithm would yield a non-trivial algorithm for standard derandomization of all of TC0TC^0, and would consequently imply that NEXP⊈TC0NEXP\not\subseteq TC^0. Specifically, if there exists a quantified derandomization algorithm that gets as input a TC0TC^0 circuit with depth dd and n1+O(1/d)n^{1+O(1/d)} wires (rather than n1+exp(d)n^{1+\exp(-d)} wires), runs in time at most 2nexp(d)2^{n^{\exp(-d)}}, and distinguishes between the case that CC rejects at most 2n11/5d2^{n^{1-1/5d}} inputs and the case that CC accepts at most 2n11/5d2^{n^{1-1/5d}} inputs, then there exists an algorithm with running time 2n1Ω(1)2^{n^{1-\Omega(1)}} for standard derandomization of TC0TC^0.Comment: Changes in this revision: An additional result (a PRG for quantified derandomization of depth-2 LTF circuits); rewrite of some of the exposition; minor correction
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