757 research outputs found

    Running anti-de Sitter radius from QCD-like strings

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    We consider renormalization effects for a bosonic QCD-like string, whose partons have 1/p21/p^{2} propagators instead of Gaussian. Classically this model resembles (the bosonic part of) the projective light-cone (zero-radius) limit of a string on an AdS5{}_5 background, where Schwinger parameters give rise to the fifth dimension. Quantum effects generate dynamics for this dimension, producing an AdS5{}_5 background with a running radius. The projective light-cone is the high-energy limit: Holography is enforced dynamically.Comment: 12 page

    Wear of Fluorapatite Single Crystals: III. Classification of Surface Failure

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    Modes of surface failure observed for natural fluorapatite single crystals under sliding were classified and related to wear and frictional behavior. The basal surfaces exhibited brittle or ductile failure depending on the combination of load and slider design. The transition occurred at penetrations of 0.3 to 0.5 μm.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67122/2/10.1177_00220345720510026101.pd

    The Green--Schwarz Superstring in Extended Configuration Space and Infinitely Reducible First Class Constraints Problem

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    The Green--Schwarz superstring action is modified to include some set of additional (on-shell trivial) variables. A complete constraints system of the theory turns out to be reducible both in the original and in additional variable sectors. The initial 8s8s first class constraints and 8c8c second class ones are shown to be unified with 8c8c first and 8s8s second class constraints from the additional variables sector, resulting with SO(1,9)SO(1,9)-covariant and linearly independent constraint sets. Residual reducibility proves to fall on second class constraints only.Comment: 14 pages, LaTe

    Baryon resonances from a novel fat-link fermion action

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    We present first results for masses of positive and negative parity excited baryons in lattice QCD using an O(a^2) improved gluon action and a Fat Link Irrelevant Clover (FLIC) fermion action in which only the irrelevant operators are constructed with fat links. The results are in agreement with earlier calculations of N^* resonances using improved actions and exhibit a clear mass splitting between the nucleon and its chiral partner, even for the Wilson fermion action. The results also indicate a splitting between the lowest J^P = 1/2^- states for the two standard nucleon interpolating fields.Comment: 5 pages, 3 figures, talk given by W.Melnitchouk at LHP 2001 workshop, Cairns, Australi

    Measuring Malware Detection Capability for Security Decision Making

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    Organizations face an urgent need to bolster their cybersecurity defenses against the rising threat of ransomware. Implementing advanced antivirus and antimalware tools is crucial for proactive identification and mitigation of malicious software. However, adversaries constantly refine malware to evade detection increasing the complexity of the threat. Hence, developing an effective strategy is nontrivial. To address this challenge, this study conducts various analyses on scan results of publicly shared malware samples. Utilizing metadata from 635K samples sourced from MalwareBazaar and scan results from VirusTotal, we assign family labels using AVClass. Additionally, we examinea 90-day longitudinal dataset alongside the main dataset. Our findings demonstrate that while over 60% of scanner engines detect 67% of samples, certain malware families consistently exhibit lower detection rates. Detection capability improves over time, particularly within the initial 30 days, but remainsinadequate for specific families. Furthermore, we observe that some scanner engines demonstrate nearly flawless detection capability across all malware families, while the majority struggle with efficiently detecting certain types. Moreover, we performed Monte Carlo simulations and revealed that employing multiple scanner engines substantially enhances detection capability, with 3 to 7 scanners being optimal. Finally, simulation analysis in a case study highlights thesignificant impact of hard-to-detect malware on risk and performance, underscoring the importance of effective malware strategies

    On the Derivation of Vector Radiative Transfer Equation for Polarized Radiative Transport in Graded Index Media

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    Light transport in graded index media follows a curved trajectory determined by the Fermat's principle. Besides the effect of variation of the refractive index on the transport of radiative intensity, the curved ray trajectory will induce geometrical effects on the transport of polarization ellipse. This paper presents a complete derivation of vector radiative transfer equation for polarized radiation transport in absorption, emission and scattering graded index media. The derivation is based on the analysis of the conserved quantities for polarized light transport along curved trajectory and a novel approach. The obtained transfer equation can be considered as a generalization of the classic vector radiative transfer equation that is only valid for uniform refractive index media. Several variant forms of the transport equation are also presented, which include the form for Stokes parameters defined with a fixed reference and the Eulerian forms in the ray coordinate and in several common orthogonal coordinate systems.Comment: This paper has been submitted to JQSR

    A Deficiency Problem of the Least Squares Finite Element Method for Solving Radiative Transfer in Strongly Inhomogeneous Media

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    The accuracy and stability of the least squares finite element method (LSFEM) and the Galerkin finite element method (GFEM) for solving radiative transfer in homogeneous and inhomogeneous media are studied theoretically via a frequency domain technique. The theoretical result confirms the traditional understanding of the superior stability of the LSFEM as compared to the GFEM. However, it is demonstrated numerically and proved theoretically that the LSFEM will suffer a deficiency problem for solving radiative transfer in media with strong inhomogeneity. This deficiency problem of the LSFEM will cause a severe accuracy degradation, which compromises too much of the performance of the LSFEM and makes it not a good choice to solve radiative transfer in strongly inhomogeneous media. It is also theoretically proved that the LSFEM is equivalent to a second order form of radiative transfer equation discretized by the central difference scheme

    Corporate financing decisions: UK survey evidence

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    Despite theoretical developments in recent years, our understanding of corporate capital structure remains incomplete. Prior empirical research has been dominated by archival regression studies which are limited in their ability to fully reflect the diversity found in practice. The present paper reports on a comprehensive survey of corporate financing decision-making in UK listed companies. A key finding is that firms are heterogeneous in their capital structure policies. About half of the firms seek to maintain a target debt level, consistent with trade-off theory, but 60 per cent claim to follow a financing hierarchy, consistent with pecking order theory. These two theories are not viewed by respondents as either mutually exclusive or exhaustive. Many of the theoretical determinants of debt levels are widely accepted by respondents, in particular the importance of interest tax shield, financial distress, agency costs and also, at least implicitly, information asymmetry. Results also indicate that cross-country institutional differences have a significant impact on financial decisions

    BRST approach to Lagrangian formulation for mixed-symmetry fermionic higher-spin fields

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    We construct a Lagrangian description of irreducible half-integer higher-spin representations of the Poincare group with the corresponding Young tableaux having two rows, on a basis of the BRST approach. Starting with a description of fermionic higher-spin fields in a flat space of any dimension in terms of an auxiliary Fock space, we realize a conversion of the initial operator constraint system (constructed with respect to the relations extracting irreducible Poincare-group representations) into a first-class constraint system. For this purpose, we find auxiliary representations of the constraint subsuperalgebra containing the subsystem of second-class constraints in terms of Verma modules. We propose a universal procedure of constructing gauge-invariant Lagrangians with reducible gauge symmetries describing the dynamics of both massless and massive fermionic fields of any spin. No off-shell constraints for the fields and gauge parameters are used from the very beginning. It is shown that the space of BRST cohomologies with a vanishing ghost number is determined only by the constraints corresponding to an irreducible Poincare-group representation. To illustrate the general construction, we obtain a Lagrangian description of fermionic fields with generalized spin (3/2,1/2) and (3/2,3/2) on a flat background containing the complete set of auxiliary fields and gauge symmetries.Comment: 41 pages, no figures, corrected typos, updated introduction, sections 5, 7.1, 7.2 with examples, conclusion with all basic results unchanged, corrected formulae (3.27), (7.138), (7.140), added dimensional reduction part with formulae (5.34)-(5.48), (7.8)-(7.10), (7.131)-(7.136), (7.143)-(7.164), added Refs. 52, 53, 54, examples for massive fields developed by 2 way

    AdS and pp-wave D-particle superalgebras

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    We derive anticommutators of supercharges with a brane charge for a D-particle in AdS(2) x S(2) and pp-wave backgrounds. A coset GL(2|2)/(GL(1))^4 and its Penrose limit are used with the supermatrix-valued coordinates for the AdS and the pp-wave spaces respectively. The brane charges have position dependence, and can be absorbed into bosonic generators by shift of momenta which results in closure of the superalgebras.Comment: 15 page
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