2,416 research outputs found
Regional evaluation of three day snow depth for avalanche hazard mapping in Switzerland
The distribution of the maximum annual three day snow fall depth <i>H<sub>72</sub></i>, used for avalanche hazard mapping according to the Swiss procedure (<i>Sp</i>), is investigated for a network of 124 stations in the Alpine part of Switzerland, using a data set dating back to 1931. Stationarity in time is investigated, showing in practice no significant trend for the considered period. Building on previous studies about climatology of Switzerland and using an iterative approach based on statistical tests for regional homogeneity and scaling of <i>H<sub>72</sub></i> with altitude, seven homogenous regions are identified. A regional approach based on the index value is then developed to estimate the <i>T</i>-years return period quantiles of <i>H<sub>72</sub></i> at each single site <i>i</i>, <i>H<sub>72i</sub>(T)</i>. The index value is the single site sample average &mu;<sub><i>H<sub>72i</sub></i></sub>. The dimensionless values of <i>H<sup>*</sup><sub>72i</sub>=H<sub>72i</sub> / &mu;<sub>H<sub>72i</sub></sub></i> are grouped in one sample for each region and their frequency of occurrence is accommodated by a General Extreme Value, GEV, probability distribution, including Gumbel. The proposed distributions, valid in each site of the homogeneous regions, can be used to assess the <i>T</i>-years return period quantiles of <i>H<sup>*</sup><sub>72i</sub></i>. It is shown that the value of <i>H<sub>72i</sub>(T)</i> estimated with the regional approach is more accurate than that calculated by single site distribution fitting, particularly for high return periods. A sampling strategy based on accuracy is also suggested to estimate the single site index value, i.e. the sample average &mu;<sub><i>H<sub>72i</sub></i></sub>, critical for the evaluation of the distribution of <i>H<sub>72i</sub></i>. The proposed regional approach is valuable because it gives more accurate snow depth input to dynamics models than the present procedure based on single site analysis, so decreasing uncertainty in hazard mapping procedure
PILOT: a balloon-borne experiment to measure the polarized FIR emission of dust grains in the interstellar medium
Future cosmology space missions will concentrate on measuring the
polarization of the Cosmic Microwave Background, which potentially carries
invaluable information about the earliest phases of the evolution of our
universe. Such ambitious projects will ultimately be limited by the sensitivity
of the instrument and by the accuracy at which polarized foreground emission
from our own Galaxy can be subtracted out. We present the PILOT balloon project
which will aim at characterizing one of these foreground sources, the
polarization of the dust continuum emission in the diffuse interstellar medium.
The PILOT experiment will also constitute a test-bed for using multiplexed
bolometer arrays for polarization measurements. We present the results of
ground tests obtained just before the first flight of the instrument.Comment: 17 pages, 13 figures. Presented at SPIE, Millimeter, Submillimeter,
and Far-Infrared Detectors and Instrumentation for Astronomy VII. To be
published in Proc. SPIE volume 915
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In Search of the Solar Wind Nitrogen Isotope Composition: Analysis of a Gold Plate from the Genesis Spacecraft Concentrator
We report N isotope analysis of a gold plate from the Genesis spacecraft concentrator. We did not find evidence for a light N component in the solar wind
MITOMAP: a human mitochondrial genome database—2004 update
MITOMAP (http://www.MITOMAP.org), a database for the human mitochondrial genome, has grown rapidly in data content over the past several years as interest in the role of mitochondrial DNA (mtDNA) variation in human origins, forensics, degenerative diseases, cancer and aging has increased dramatically. To accommodate this information explosion, MITOMAP has implemented a new relational database and an improved search engine, and all programs have been rewritten. System administrative changes have been made to improve security and efficiency, and to make MITOMAP compatible with a new automatic mtDNA sequence analyzer known as Mitomaster
Declining Population Sizes and Loss of Genetic Diversity in Commercial Fishes: A Simple Method for a First Diagnostic
Exploited fish species may have or are experiencing declines in population sizes coupled
with changes in their environmental conditions owing to global change. Declining
populations might lead to a decrease in genetic diversity, which in turn may produce
losses of adaptive potential to face current and future environmental changes. Thus, this
study aims to answer a simple, even naive question, given the complexity of the subject:
Could we use a simple method to obtain information on the loss of genetic diversity in
exploited fish species? We investigated the use of the levels of genetic diversity in the
widely used genetic marker Cytochrome C Oxidase subunit I (COI) mitochondrial gene.
Estimates of genetic diversity in COI were obtained for populations of seven fish species
with different commercial importance from the East China Sea. These estimates were
contrasted against large datasets of genetic diversity in COI for fish species (East-Asian
N=118, and worldwide N=1425), and six control species with known biology and history.
We found that estimates of genetic diversity in COI match the expectations from
theoretical predictions and known declines by fishing pressures. Thus, the answer to
our question is affirmative and we conclude that estimates of genetic diversity in COI
provide an effective first diagnostic of the conservation status of exploited fish species.En prens
Coupled phonon-ripplon modes in a single wire of electrons on the liquid-helium surface
The coupled phonon-ripplon modes of the quasi-one-dimensional electron chain
on the liquid helium sutface are studied. It is shown that the electron-ripplon
coupling leads to the splitting of the collective modes of the wire with the
appearance of low-frequency modes and high-frequency optical modes starting
from threshold frequencies. The effective masses of an electron plus the
associated dimple for low frequency modes are estimated and the values of the
threshold frequencies are calculated. The results obtained can be used in
experimental attempts to observe the phase transition of the electron wire into
a quasi-ordered phase.Comment: 5 pages, 1 figure, Physical Review (in press
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