185 research outputs found
Due Process and National Security
Dressler v. Wilson, 155 F. Supp. 373 (D.C. D.C. 1957)
Quantum Fields and Extended Objects in Space-Times with Constant Curvature Spatial Section
The heat-kernel expansion and -regularization techniques for quantum
field theory and extended objects on curved space-times are reviewed. In
particular, ultrastatic space-times with spatial section consisting in manifold
with constant curvature are discussed in detail. Several mathematical results,
relevant to physical applications are presented, including exact solutions of
the heat-kernel equation, a simple exposition of hyperbolic geometry and an
elementary derivation of the Selberg trace formula. With regards to the
physical applications, the vacuum energy for scalar fields, the one-loop
renormalization of a self-interacting scalar field theory on a hyperbolic
space-time, with a discussion on the topological symmetry breaking, the finite
temperature effects and the Bose-Einstein condensation, are considered. Some
attempts to generalize the results to extended objects are also presented,
including some remarks on path integral quantization, asymptotic properties of
extended objects and a novel representation for the one-loop (super)string free
energy.Comment: Latex file, 122 page
Four-dimensional String Compactifications with D-Branes, Orientifolds and Fluxes
This review article provides a pedagogical introduction into various classes
of chiral string compactifications to four dimensions with D-branes and fluxes.
The main concern is to provide all necessary technical tools to explicitly
construct four-dimensional orientifold vacua, with the final aim to come as
close as possible to the supersymmetric Standard Model. Furthermore, we outline
the available methods to derive the resulting four-dimensional effective
action. Finally, we summarize recent attempts to address the string vacuum
problem via the statistical approach to D-brane models.Comment: 331 pages, 7 figures, review prepared for Physics Reports, please
send constructive comments to: [email protected], v2: refs added, v3: final
version to appear in Phys. Rep
The Fischer 344 Rat Reflects Human Susceptibility to Francisella Pulmonary Challenge and Provides a New Platform for Virulence and Protection Studies
Background: The pathogenesis of Francisella tularensis, the causative agent of tularemia, has been primarily characterized in mice. However, the high degree of sensitivity of mice to bacterial challenge, especially with the human virulent strains of F. tularensis, limits this animal model for screening of defined attenuated vaccine candidates for protection studies. Methods and Findings: We analyzed the susceptibility of the Fischer 344 rat to pulmonary (intratracheal) challenge with three different subspecies (subsp) of F. tularensis that reflect different levels of virulence in humans, and characterized the bacterial replication profile in rat bone marrow-derived macrophages (BMDM). In contrast to the mouse, Fischer 344 rats exhibit a broader range of sensitivity to pulmonary challenge with the human virulent subsp. tularensis and holarctica. Unlike mice, Fischer rats exhibited a high degree of resistance to pulmonary challenge with LVS (an attenuated derivative o
2-Mercapto-Quinazolinones as Inhibitors of Type II NADH Dehydrogenase and Mycobacterium tuberculosis:Structure-Activity Relationships, Mechanism of Action and Absorption, Distribution, Metabolism, and Excretion Characterization
<i>Mycobacterium tuberculosis</i> (<i>MTb</i>) possesses
two nonproton pumping type II NADH dehydrogenase (NDH-2)
enzymes which are predicted to be jointly essential for respiratory
metabolism. Furthermore, the structure of a closely related bacterial
NDH-2 has been reported recently, allowing for the structure-based
design of small-molecule inhibitors. Herein, we disclose <i>MTb</i> whole-cell structure–activity relationships (SARs) for a series of 2-mercapto-quinazolinones which target the <i>ndh</i> encoded NDH-2 with nanomolar potencies. The compounds were inactivated by glutathione-dependent adduct formation as well as quinazolinone oxidation in microsomes. Pharmacokinetic studies demonstrated modest bioavailability and compound exposures. Resistance to the compounds in <i>MTb</i> was conferred by promoter mutations in the alternative nonessential NDH-2 encoded by <i>ndhA</i> in <i>MTb</i>. Bioenergetic analyses revealed a decrease in oxygen consumption rates in response to inhibitor in cells in which membrane potential was uncoupled from ATP production, while inverted membrane vesicles showed mercapto-quinazolinone-dependent inhibition of ATP production when NADH was the electron donor to the respiratory chain. Enzyme kinetic studies further demonstrated noncompetitive inhibition, suggesting binding of this scaffold to an allosteric site. In summary, while the initial <i>MTb</i> SAR showed limited improvement in potency, these results, combined with structural information on the bacterial protein, will aid in the future discovery of new and improved NDH-2 inhibitors
Proton stability in grand unified theories, in strings, and in branes
A broad overview of the current status of proton stability in unified models
of particle interactions is given which includes non - supersymmetric
unification, SUSY and SUGRA unified models, unification based on extra
dimensions, and string-M-theory models. The extra dimensional unification
includes 5D and 6D and universal extra dimensional (UED) models, and models
based on warped geometry. Proton stability in a wide array of string theory and
M theory models is reviewed. These include Calabi-Yau models, grand unified
models with Kac-Moody levels , a new class of heterotic string models,
models based on intersecting D branes, and string landscape models. The
destabilizing effect of quantum gravity on the proton is discussed. The
possibility of testing grand unified models, models based on extra dimensions
and string-M-theory models via their distinctive modes is investigated. The
proposed next generation proton decay experiments, HyperK, UNO, MEMPHYS,
ICARUS, LANNDD (DUSEL), and LENA would shed significant light on the nature of
unification complementary to the physics at the LHC. Mathematical tools for the
computation of proton lifetime are given in the appendices. Prospects for the
future are discussed.Comment: Published in Physics Reports. 258 pages, 11 figure
PSR J1024-0719:A Millisecond Pulsar in an Unusual Long-Period Orbit
PSR J1024-0719 is a millisecond pulsar that was long thought to be isolated. However, puzzling results concerning its velocity, distance, and low rotational period derivative have led to a reexamination of its properties. We present updated radio timing observations along with new and archival optical data which show that PSR J1024-0719 is most likely in a long-period (2-20 kyr) binary system with a low-mass (approximate to 0.4 M-circle dot), low-metallicity (Z approximate to -0.9 dex) main-sequence star. Such a system can explain most of the anomalous properties of this pulsar. We suggest that this system formed through a dynamical exchange in a globular cluster that ejected it into a halo orbit, which is consistent with the low observed metallicity for the stellar companion. Further astrometric and radio timing observations such as measurement of the third period derivative could strongly constrain the range of orbital parameters
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