High energy muons and neutrinos are produced by the interaction of primary cosmic rays in the Earth's upper atmosphere. These primary interactions produce mesons which decay into muons and neutrinos. ...SNO is in a unique position amongst world experiments located underground. At the depth of over 6 km water equivalent, it is the deepest underground laboratory currently in operation. SNO can make a number of important measurements using muons. First, SNO is sensitive to the downward muon rate coming from primary cosmic ray interactions. Second, SNO's depth allows for a measurement of atmospheric neutrinos (via the detection of neutrino-induced muons) at inclinations as large as
cos
(
θ
zenith
)
≃
0.4
. Although SNO is a modest-size Cherenkov detector, its unique niche allows it to make important model-independent checks of atmospheric neutrino oscillations as well as measurements for cosmic rays and muon spallation.
Summary
We present here the results of the Analysis of
HLA
Population Data (
AHPD
) project of the 16th International
HLA
and Immunogenetics Workshop (16
IHIW
) held in Liverpool in May–June 2012. ...Thanks to the collaboration of 25 laboratories from 18 different countries,
HLA
genotypic data for 59 new population samples (either well‐defined populations or donor registry samples) were gathered and 55 were analysed statistically following
HLA
‐
NET
recommendations. The new data included, among others, large sets of well‐defined populations from north‐east Europe and West Asia, as well as many donor registry data from European countries. The
Gene
rate
computer tools were combined to create a
Gene
rate
computer pipeline
to automatically (i) estimate allele frequencies by an expectation‐maximization algorithm accommodating ambiguities, (ii) estimate heterozygosity, (iii) test for Hardy–Weinberg equilibrium (HWE), (iv) test for selective neutrality, (v) generate frequency graphs and summary statistics for each sample at each locus and (vi) plot multidimensional scaling (
MDS
) analyses comparing the new samples with previous
IHIW
data. Intrapopulation analyses show that HWE is rarely rejected, while neutrality tests often indicate a significant excess of heterozygotes compared with neutral expectations. The comparison of the 16
IHIW AHPD
data with data collected during previous workshops (12th–15th) shows that geography is an excellent predictor of
HLA
genetic differentiations for
HLA
‐A, ‐B and ‐
DRB
1 loci but not for
HLA
‐
DQ
, whose patterns are probably more influenced by natural selection. In Europe,
HLA
genetic variation clearly follows a north to south‐east axis despite a low level of differentiation between European, North African and West Asian populations. Pacific populations are genetically close to Austronesian‐speaking South‐East Asian and Taiwanese populations, in agreement with current theories on the peopling of Oceania. Thanks to this project,
HLA
genetic variation is more clearly defined worldwide and better interpreted in relation to human peopling history and
HLA
molecular evolution.
We report on a new zero-field spin-echo spectrometer (ZETA), installed at the thermal three-axis spectrometer IN3 at ILL, Grenoble. In this technique the two long precession solenoids from neutron ...spin echo are replaced by two pairs of magnetic resonance coils in a zero-field region. This allows easy adaptation of tilted field geometries, necessary for measurements of phonon line widths with μeV energy resolution. First test measurements of the roton line width and energy shift as well as line width of the low-
Q phonon and in the “region beyond the roton” in superfluid
4He are described. The results are in agreement with the literature and show the good operation of ZETA. The implementation of ZETA at the high-flux three-axis spectrometer IN20, foreseen in the near future, will increase the count rate by typically one order of magnitude.
Uranium is the only element known so far to exhibit a charge-density wave (CDW) instability (alpha phase; orthorhombic Cmcm space group,
Z=4,
T
o
=43
K
). The structure below the transition is ...complex, consisting of small displacements of the atoms along all three of the orthorhombic axis. The main displacement is associated with a doubling of the
a
-axis, and it has been known for many years that the transition may be regarded as one in which a soft phonon condenses at this point half way across the Brillouin zone. The theory of Yamada (1993, Phys. Rev. B 47, 5641) suggests that the only important component of the phonon wave vector is that along 1
0
0. We report here high-resolution neutron scattering experiments at low temperature which show that the principal softening occurs at the exact CDW points in the Brillouin zone. This result is in disagreement with the suggestions of Yamada but in better agreement with a new theoretical approach by Fast (1998, Ph.D. Thesis, Uppsala University, Sweden).
Uranium is the only element known so far to exhibit a charge-density wave (CDW) instability. The structure below the transition (
T
0 ∼ 43
K) is complex consisting of small displacements of the atoms ...away from their α-phase equilibrium positions. It is usually assumed that this transition involves a soft phonon condensing at (or near) the CDW position in the Brillouin zone. High-resolution neutron scattering experiments at low temperature show that the principal softening occurs
exactly at the CDW positions, as expected for a pure Fermi-surface instability. This result is in agreement with a recent theory which suggests that the CDW-vector components are related to the Fermi-surface nesting topology.
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