8,802 research outputs found
Physics with a very long neutrino factory baseline
We discuss the neutrino oscillation physics of a very long neutrino factory
baseline over a broad range of lengths (between 6000 km and 9000 km), centered
on the ``magic baseline'' ( 7500 km) where correlations with the leptonic
CP phase are suppressed by matter effects. Since the magic baseline depends
only on the density, we study the impact of matter density profile effects and
density uncertainties over this range, and the impact of detector locations off
the optimal baseline. We find that the optimal constant density describing the
physics over this entire baseline range is about 5% higher than the average
matter density. This implies that the magic baseline is significantly shorter
than previously inferred. However, while a single detector optimization
requires fine-tuning of the (very long) baseline length, its combination with a
near detector at a shorter baseline is much less sensitive to the far detector
location and to uncertainties in the matter density. In addition, we point out
different applications of this baseline which go beyond its excellent
correlation and degeneracy resolution potential. We demonstrate that such a
long baseline assists in the improvement of the precision and in
the resolution of the octant degeneracy. Moreover, we show that the neutrino
data from such a baseline could be used to extract the matter density along the
profile up to 0.24% at for large , providing a
useful discriminator between different geophysical models.Comment: 27 pages, 11 figures. Minor changes, references added; version to
appear in Phys. Rev.
Evaluation of Striped Bass (Morone saxatillis) Age from Body Scales, Opercles, and Dorsal Spines
Assessing the impact of prompt corrective action on bank capital and risk
This paper was presented at the conference "Financial services at the crossroads: capital regulation in the twenty-first century" as part of session 1, "Impact of capital requirements on bank risk taking: empirical evidence." The conference, held at the Federal Reserve Bank of New York on February 26-27, 1998, was designed to encourage a consensus between the public and private sectors on an agenda for capital regulation in the new century.Bank capital ; Bank supervision ; Risk ; Bank investments
Learning Model-Based Sparsity via Projected Gradient Descent
Several convex formulation methods have been proposed previously for
statistical estimation with structured sparsity as the prior. These methods
often require a carefully tuned regularization parameter, often a cumbersome or
heuristic exercise. Furthermore, the estimate that these methods produce might
not belong to the desired sparsity model, albeit accurately approximating the
true parameter. Therefore, greedy-type algorithms could often be more desirable
in estimating structured-sparse parameters. So far, these greedy methods have
mostly focused on linear statistical models. In this paper we study the
projected gradient descent with non-convex structured-sparse parameter model as
the constraint set. Should the cost function have a Stable Model-Restricted
Hessian the algorithm produces an approximation for the desired minimizer. As
an example we elaborate on application of the main results to estimation in
Generalized Linear Model
Large-scale Synthesis and Functional Elements for the Antimicrobial Activity of Defensins
Human neutrophil defensins, and their analogues incorporating anionic, hydrophobic or cationic residues at the N- and C-termini, were synthesized by solid-phase procedures. The synthetic defensins were examined for their microbicidal activity against Candida albicans, two Gram-negative bacteria (Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis) and two Gram-positive bacteria (Streptococcus gordonii and Streptococcus mutans). The human neutrophil peptide 1 (HNP1) and HNP2 were found to be potent candidacidal agents. HNP3, which differs by one amino acid at the N-terminus of its sequence, was totally inactive. The Gram-negative bacteria A. actinomycetemcomitans and P. gingivalis and the Gram-positive bacteria S. gordonii and S. mutans were insensitive to human defensins. However, the insertion of two basic residues, such as arginine, at both the N-terminus and the C-terminus of HNP2 significantly enhanced antifungal and antibacterial activity. The addition of anionic residues, such as aspartic acid, at the N- and C-termini rendered the molecule totally inactive. The presence of two hydrophobic amino acids, such as valine, at the N-terminus of HNP2 and of two basic arginine residues at its C-terminus resulted in molecules that were optimally active against these oral pathogens. The results suggest that the N- and C-terminal residues in defensin peptides are the crucial functional elements that determine their microbicidal potency. The three-dimensional structure of all defensins constitutes the same amphiphilic beta-sheet structure, with the polar face formed by the N- and C-terminal residues playing an important role in defining microbicidal potency and the antimicrobial spectrum. The enhanced microbicidal activity observed for defensin peptides with two basic residues at both the N- and C-termini could be due to optimization of the amphiphilicity of the structure, which could facilitate specific interactions with the microbial membranes
The apterous endemic genus Omphra Dejean (Coleoptera: Carabidae: Helluonini) of the Indian subcontinent : taxonomy with notes on habits and distributional patterns
Among the four oriental genera of the tribe Helluonini, Omphra Dejean (Coleoptera: Carabidae), is unique for its endemism to the Indian subcontinent and aptery. High intraspecies variability in morphological characters and limited diagnostic information makes species differentiation of the genus Omphra a complicated task. The present study provides a description of a new species, Omphra drumonti n. sp. from the Western Ghats, redescriptions and a key to the species of Omphra, details of intraspecies variation, discussion of relationships between taxa and distributional patterns of the genus. Based on the distributional patterns in the Indian subcontinent and flightlessness of the genus, inability to cross the physical barrier of the Ganges–Brahmaputra delta between north and peninsular India is indicated as the reason for its absence in the northeastern Indian subcontinent and endemism to the lower Indian subcontinent
DARIS, a fleet of passive formation flying small satellites for low frequency radio astronomy
DARIS (Distributed Aperture Array for Radio Astronomy In Space) is a mission to conduct radio astronomy in the low frequency region from 1-10MHz. This region has not yet been explored, as the Earth's ionosphere is opaque to those frequencies, and so a space based observatory is the only solution. DARIS will undertake an extragalactic survey of the low frequency sky, and can also detect some transient radio events such as solar or planetary bursts. To achieve these scientific objectives, DARIS comprises a space-based array, forming a very large effective aperture, as required for such a long wavelength survey. Each station in the array (each required to be a small satellite to ensure several nodes can be flown) carries three orthogonal dipole antennas, each 5m in length. The more station nodes in the array, the more sensitive the antenna. The entire fleet remains within a 100km diameter cloud. \ud
A very large data volume is generated by each node, as the antennas have to capture all radio signals, after which the data can be correlated to find the astronomical signal in the noise. As the astronomical signals also have a noise-like nature, no compression is possible on the data captured by the nodes. The data volume is too high to transfer directly to Earth, and will need to be correlated in space. Distributed correlation between the nodes is technically challenging, and therefore a mothership acts as the central correlator and then downlinks the correlated data (lower volume) to Earth. \u
- …