23,439 research outputs found

    On Ward Identities in Lifshitz-like Field Theories

    Get PDF
    In this work, we develop a normal product algorithm suitable to the study of anisotropic field theories in flat space, apply it to construct the symmetries generators and describe how their possible anomalies may be found. In particular, we discuss the dilatation anomaly in a scalar model with critical exponent z=2 in six spatial dimensions.Comment: Clarifications adde

    The success factors for SMEs: Empirical evidence

    Get PDF
    This paper empirically analyzes the success factors for SMEs. Particularly, the paper intends to analyze if firm age, human resource costs, debt, venture capital funding, investment in innovation and productivity are success factors for SMEs. The effects were tested using static and dynamic panel data, on a data set of 200 Portuguese SMEs. The use of dynamic panel data is important in order to control for: endogeneity; time-invariant characteristics; possible collinearity between independent variables; effects from possible omission of independent variables; elimination of non-observable individual effects; and, the correct estimation of the relationship between the dependent variable in the previous and current periods. Our results reveal a positive impact on success of: human resource costs; investments in innovation; productivity; and, venture capital funding. We also confirm the negative impact of firm age and debt. Also, the results show evidence of persistence in success for the case of one of the success proxies used

    Cooperative localization-delocalization in the high Tc cuprates

    Full text link
    The intrinsic metastable crystal structure of the cuprates results in local dynamical lattice instabilities, strongly coupled to the density fluctuations of the charge carriers. They acquire in this way simultaneously both, delocalized and localized features. It is responsible for a partial fractioning of the Fermi surface, i.e., the Fermi surface gets hidden in a region around the anti-nodal points, because of the opening of a pseudogap in the normal state, arising from a partial charge localization. The high energy localized single-particle features are a result of a segregation of the homogeneous crystal structure into checker-board local nano-size structures, which breaks the local translational and rotational symmetry. The pairing in such a system is dynamical rather than static, whereby charge carriers get momentarily trapped into pairs in a deformable dynamically fluctuating ligand environment. We conclude that the intrinsically heterogeneous structure of the cuprates must play an important role in this type of superconductivity.Comment: 14 pages, 8 figures, Proceedings of the "International Conference on Condensed Matter Theories", Quito, 2009 Int. J. Mod. Phys. B 2010 (Accepted

    An Exploratory Review of Bangladesh Gas Sector: Latest Evidence and Areas of Further Research

    Get PDF
    This paper reviews and explores the latest evidence from the gas sector of Bangladesh and highlights areas that would benefit from further research. The study reported actual consumption of gas by different sectors; projection of demands by various studies and plan documents; estimates of gas reserves and potential by various studies; and operation of the International Oil Companies (IOCs) in Bangladesh.Gas Sector, Bangladesh

    Ileocecal appendix involvement in fabry disease mimicking an acute abdomen

    Get PDF
    Anderson-Fabry disease (AFD) is a rare, X-linked, lysosomal storage disorder due to a deficiency of alphagalactosidase A. The direct consequence is a lipid storage with the accumulation of glycosphingolipids throughout the body. The clinical picture is highly variable and depends on cellular storage deposition ranging from neurological, cutaneous and renal symptoms to cardiac and gastrointestinal ones. We are reporting about the case of a young female carrier of alpha-galactosidase A (agalA) gene mutation who was treated at our out-clinic practice for minimal neurological involvement (achroparaestesia). She was subsequently admitted in order to undergo appendectomy because of an acute severe abdominal pain. The histological examination of her appendix revealed only a deposition of globotriaosylceramide (Gb3) without any sign of acute inflammation. This case confirms the extreme clinical variability of Fabry disease and how the gastrointestinal involvement diagnosis can be misse

    Quantifying Equivocation for Finite Blocklength Wiretap Codes

    Full text link
    This paper presents a new technique for providing the analysis and comparison of wiretap codes in the small blocklength regime over the binary erasure wiretap channel. A major result is the development of Monte Carlo strategies for quantifying a code's equivocation, which mirrors techniques used to analyze normal error correcting codes. For this paper, we limit our analysis to coset-based wiretap codes, and make several comparisons of different code families at small and medium blocklengths. Our results indicate that there are security advantages to using specific codes when using small to medium blocklengths.Comment: Submitted to ICC 201

    Phase Diagram of the Attractive Hubbard Model with Inhomogeneous Interactions

    Full text link
    The phase diagram of the attractive Hubbard model with spatially inhomogeneous interactions is obtained using a single site dynamical mean field theory like approach. The model is characterized by three parameters: the interaction strength, the active fraction (fraction of sites with the attractive interaction), and electron filling. The calculations indicate that in a parameter regime with intermediate values of interaction strength (compared to the bare bandwidth of the electrons), and intermediate values of the active fraction, "non-BCS" superconductivity is obtained. The results of this work are likely to be relevant to many systems with spatially inhomogeneous superconductivity such as strongly correlated oxides, systems with negative U centers, and, in future, cold atom optical lattices.Comment: 9 pages, 7 figures, to appear in Physical Review
    corecore