757 research outputs found
Running anti-de Sitter radius from QCD-like strings
We consider renormalization effects for a bosonic QCD-like string, whose
partons have propagators instead of Gaussian. Classically this model
resembles (the bosonic part of) the projective light-cone (zero-radius) limit
of a string on an AdS background, where Schwinger parameters give rise to
the fifth dimension. Quantum effects generate dynamics for this dimension,
producing an AdS 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
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
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 first class constraints and second
class ones are shown to be unified with first and second class
constraints from the additional variables sector, resulting with
-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
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
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
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
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
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
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
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
- …