4,705 research outputs found
An Algorithmic Approach to Quantum Field Theory
The lattice formulation provides a way to regularize, define and compute the
Path Integral in a Quantum Field Theory. In this paper we review the
theoretical foundations and the most basic algorithms required to implement a
typical lattice computation, including the Metropolis, the Gibbs sampling, the
Minimal Residual, and the Stabilized Biconjugate inverters. The main emphasis
is on gauge theories with fermions such as QCD. We also provide examples of
typical results from lattice QCD computations for quantities of
phenomenological interest.Comment: 44 pages, to be published in IJMP
Information Security as Strategic (In)effectivity
Security of information flow is commonly understood as preventing any
information leakage, regardless of how grave or harmless consequences the
leakage can have. In this work, we suggest that information security is not a
goal in itself, but rather a means of preventing potential attackers from
compromising the correct behavior of the system. To formalize this, we first
show how two information flows can be compared by looking at the adversary's
ability to harm the system. Then, we propose that the information flow in a
system is effectively information-secure if it does not allow for more harm
than its idealized variant based on the classical notion of noninterference
Second large-scale Monte Carlo study for the Cherenkov Telescope Array
The Cherenkov Telescope Array (CTA) represents the next generation of ground
based instruments for Very High Energy gamma-ray astronomy. It is expected to
improve on the sensitivity of current instruments by an order of magnitude and
provide energy coverage from 20 GeV to more than 200 TeV. In order to achieve
these ambitious goals Monte Carlo (MC) simulations play a crucial role, guiding
the design of CTA. Here, results of the second large-scale MC production are
reported, providing a realistic estimation of feasible array candidates for
both Northern and Sourthern Hemisphere sites performance, placing CTA
capabilities into the context of the current generation of High Energy
-ray detectors.Comment: In Proceedings of the 34th International Cosmic Ray Conference
(ICRC2015), The Hague, The Netherlands. All CTA contributions at
arXiv:1508.0589
Ethical leaders and leadership effectiveness: the moderating role of individual differences in need for cognitive closure
Ethical leadership is an important factor in leadership effectiveness, but the study of the contingencies of its influence is still in its infancy. Addressing this issue we focus on the moderating role of followers’ need for cognitive closure, the disposition to reduce uncertainty and swiftly reach closure in judgment and decision, in the relationship between ethical leadership and its effectiveness. We propose that need for closure captures followers’ sensitivity to the uncertaintyreducing influence of ethical leadership. In a field survey study we found support for the hypothesis that perceived ethical leadership has a stronger (positive) relationship with leadership effectiveness for followers higher in need for closure. This support is found across two indicators reflecting different aspects of leadership effectiveness: effort investment and job satisfaction. We discuss how these findings advance our understanding of the uncertainty-reducing role of ethical leadership
Mode Confinement in Photonic Quasi-Crystal Point-Defect Cavities for Particle Accelerators
In this Letter, we present a study of the confinement properties of
point-defect resonators in finite-size photonic-bandgap structures composed of
aperiodic arrangements of dielectric rods, with special emphasis on their use
for the design of cavities for particle accelerators. Specifically, for
representative geometries, we study the properties of the fundamental mode (as
a function of the filling fraction, structure size, and losses) via 2-D and 3-D
full-wave numerical simulations, as well as microwave measurements at room
temperature. Results indicate that, for reduced-size structures, aperiodic
geometries exhibit superior confinement properties by comparison with periodic
ones.Comment: 4 pages, 4 figures, accepted for publication in Applied Physics
Letter
Monte Carlo Performance Studies of Candidate Sites for the Cherenkov Telescope Array
The Cherenkov Telescope Array (CTA) is the next-generation gamma-ray
observatory with sensitivity in the energy range from 20 GeV to beyond 300 TeV.
CTA is proposed to consist of two arrays of 40-100 imaging atmospheric
Cherenkov telescopes, with one site located in each of the Northern and
Southern Hemispheres. The evaluation process for the candidate sites for CTA is
supported by detailed Monte Carlo simulations, which take different attributes
like site altitude and geomagnetic field configuration into account. In this
contribution we present the comparison of the sensitivity and performance of
the different CTA site candidates for the measurement of very-high energy gamma
rays.Comment: In Proceedings of the 34th International Cosmic Ray Conference
(ICRC2015), The Hague, The Netherlands. All CTA contributions at
arXiv:1508.0589
Analysis and characterization of mouse monoclonal antibodies reactive to Chikungunya virus (CHIKV)
occurring in 1984). However, plague has made an astonishing comeback in the last decade. Methods: n/a. Results: After a silence of 50 years, an outbreak of bubonic plague suddenly occurred close to Oran in Algeria, in June 2003. Eighteen bubonic cases were identified, and Yersinia pestis was isolated from 6 patients. In July 2008, a new cluster was reported among nomads 300 km south of the first one. Four members of one family were affected and one died. The bacillus was isolated from one patient. No epidemiological association was identified between the two events. On June 2009, 25 years after the last occurrence in the country, Libya reported five confirmed cases of bubonic plague in the Tobruk area. Y. pestis was isolated from three patients. In all these cases, further local ecological investigations confirmed the existence of a natural focus The re-emergence of human plague in the region is not without international consequences. Two of the last concerned natural foci are close to an international port which raises the question of the potential exportation of infected rodents. Cross-border tensions, between ''plague countries'' and ''plague-free countries'' have been observed although the foci's limits are unknown as any systematic ecological investigation and surveillance is lacking. Additionally, the potential weaponization of Y.pestis together with international political tensions feed a recurrent interest in plague in North Africa. False rumors of alleged military laboratory accidents or terrorist acts are routinely mentioned, although events could be first explained by the natural history of the disease. Conclusion: In this context, and although the number of human cases has been very limited so far, the first priorities are to establish appropriate ecological surveillance and agree on a common plague control strategy for the region
Estimating offspring production using capture-mark-recapture and genetic methods in red squirrels.
Reproductive rate is a key demographic
parameter of life history and population ecology.
In traditional population-ecology studies of small
mammals, this and other vital rates are inferred from
capture-mark-recapture (CMR) data. However, CMR
assumes that immigrants at first capture can be distinguished
from unmarked locally born offspring, an
assumption not always met. We verified CMR estimates
of locally born red squirrel (Sciurus vulgaris) offspring as
a measure of reproductive rate, with candidate offspring
(CO)\u2013candidate parent (mothers, CPs) assignment by
CERVUS, using ten DNA microsatellite loci. Seventytwo
of 122 candidate offspring (59%) were assigned to
52 of 125 CPs in six populations. Estimates of mean
litter size were 1.5 young (range 1\u20133). The 50 CO (41%)
not assigned to a reproducing female in the study site
were considered immigrants. Parentage assignment also
provided evidence of dispersal between two of our sites.
Overall, CMR and CERVUS agreed in 77% of cases.
Considering only the 55 juveniles determined as locally
born by CMR, 50 (91%) were also assigned as local
offspring with CERVUS. The main discrepancy between
the two methods was that 22 subadult squirrels classified
immigrants by CMR, were assigned by CERVUS to
females which had reproduced in our sites. It is concluded
that although in our study system agreement
between CMR and CERVUS in determining local offspring
was high, using genetic parentage assignment
helped to correctly classify some subadults, considered
immigrants by CMR, as locally born. Hence, in largescale
demographic studies, combining CMR with parentage
assignment will allow more precise estimates of
reproduction and dispersal
Monte Carlo Performance Studies for the Site Selection of the Cherenkov Telescope Array
The Cherenkov Telescope Array (CTA) represents the next generation of
ground-based instruments for very-high-energy (VHE) gamma-ray astronomy, aimed
at improving on the sensitivity of current-generation experiments by an order
of magnitude and providing coverage over four decades of energy. The current
CTA design consists of two arrays of tens of imaging atmospheric Cherenkov
telescopes, comprising Small, Medium and Large-Sized Telescopes, with one array
located in each of the Northern and Southern Hemispheres. To study the effect
of the site choice on the overall \gls{cta} performance and support the site
evaluation process, detailed Monte Carlo simulations have been performed. These
results show the impact of different site-related attributes such as altitude,
night-sky background and local geomagnetic field on CTA performance for the
observation of VHE gamma rays.Comment: 34 pages, 11 figures, Accepted for publication in AP
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