383 research outputs found
Searches for violation of fundamental time reversal and space reflection symmetries in solid state experiments
The electric dipole moment (EDM) of a particle violates both time reversal
(T) and space reflection (P) symmetries. There have been recent suggestions for
searches of the electron EDM using solid state experiments [1,2]. These
experiments could improve the sensitivity compared to present atomic and
molecular experiments by several orders of magnitude. In the present paper we
calculate the expected effect. We also suggest that this kind of experiment is
sensitive to T,P-violation in nuclear forces and calculate effects caused by
the nuclear Schiff moment.
The compounds under consideration contain magnetic Gd ions and oxygen
O ions. We demonstrate that the main mechanism for the T,P-odd effects
is related to the penetration of the Oxygen 2p-electrons to the Gd core. All
the effects are related to the deformation of the crystal lattice.Comment: 13 pages, 6 figure
Dark matter in UED : the role of the second KK level
We perform a complete calculation of the relic abundance of the KK-photon LKP
in the universal extra dimension model including all coannihilation channels
and all resonances. We show that the production of level 2 particles which
decay dominantly into SM particles contribute significantly to coannihilation
processes involving level 1 KK-leptons. As a result the preferred dark matter
scale is increased to ~TeV. A dark matter candidate at or below the
TeV scale can only be found in the non-minimal model by reducing the mass
splittings between the KK-particles and the LKP. The LKP nucleon scattering
cross section is typically small, ~pb, unless the KK-quarks
are nearly degenerate with the LKP.Comment: 18 pages, 6 figure
Enhancement of the electron electric dipole moment in gadolinium garnets
Effects caused by the electron electric dipole moment (EDM) in gadolinium
garnets are considered. Experimental studies of these effects could improve
current upper limit on the electron EDM by several orders of magnitude. We
suggest a consistent theoretical model and perform calculations of observable
effects in gadolinium gallium garnet and gadolinium iron garnet. Our
calculation accounts for both direct and exchange diagrams.Comment: 9 page
Systematic evaluation and validation of reference and library selection methods for deconvolution of cord blood DNA methylation data
Background: Umbilical cord blood (UCB) is commonly used in epigenome-wide association studies of prenatal
exposures. Accounting for cell type composition is critical in such studies as it reduces confounding due to the cell
specificity of DNA methylation (DNAm). In the absence of cell sorting information, statistical methods can be
applied to deconvolve heterogeneous cell mixtures. Among these methods, reference-based approaches leverage
age-appropriate cell-specific DNAm profiles to estimate cellular composition. In UCB, four reference datasets
comprising DNAm signatures profiled in purified cell populations have been published using the Illumina 450 K and
EPIC arrays. These datasets are biologically and technically different, and currently, there is no consensus on how to
best apply them. Here, we systematically evaluate and compare these datasets and provide recommendations for
reference-based UCB deconvolution.
Results: We first evaluated the four reference datasets to ascertain both the purity of the samples and the potential
cell cross-contamination. We filtered samples and combined datasets to obtain a joint UCB reference. We selected
deconvolution libraries using two different approaches: automatic selection using the top differentially methylated
probes from the function pickCompProbes in minfi and a standardized library selected using the IDOL (Identifying
Optimal Libraries) iterative algorithm. We compared the performance of each reference separately and in
combination, using the two approaches for reference library selection, and validated the results in an independent
cohort (Generation R Study, n = 191) with matched Fluorescence-Activated Cell Sorting measured cell counts. Strict
filtering and combination of the references significantly improved the accuracy and efficiency of cell type estimates.
Ultimately, the IDOL library outperformed the library from the automatic selection method implemented in
pickCompProbes.
Conclusion: These results have important implications for epigenetic studies in UCB as implementing this method
will optimally reduce confounding due to cellular heterogeneity. This work provides guidelines for future referencebased UCB deconvolution and establishes a framework for combining reference datasets in other tissues
Modeling the Subsurface Structure of Sunspots
While sunspots are easily observed at the solar surface, determining their
subsurface structure is not trivial. There are two main hypotheses for the
subsurface structure of sunspots: the monolithic model and the cluster model.
Local helioseismology is the only means by which we can investigate
subphotospheric structure. However, as current linear inversion techniques do
not yet allow helioseismology to probe the internal structure with sufficient
confidence to distinguish between the monolith and cluster models, the
development of physically realistic sunspot models are a priority for
helioseismologists. This is because they are not only important indicators of
the variety of physical effects that may influence helioseismic inferences in
active regions, but they also enable detailed assessments of the validity of
helioseismic interpretations through numerical forward modeling. In this paper,
we provide a critical review of the existing sunspot models and an overview of
numerical methods employed to model wave propagation through model sunspots. We
then carry out an helioseismic analysis of the sunspot in Active Region 9787
and address the serious inconsistencies uncovered by
\citeauthor{gizonetal2009}~(\citeyear{gizonetal2009,gizonetal2009a}). We find
that this sunspot is most probably associated with a shallow, positive
wave-speed perturbation (unlike the traditional two-layer model) and that
travel-time measurements are consistent with a horizontal outflow in the
surrounding moat.Comment: 73 pages, 19 figures, accepted by Solar Physic
Detector Description and Performance for the First Coincidence Observations between LIGO and GEO
For 17 days in August and September 2002, the LIGO and GEO interferometer
gravitational wave detectors were operated in coincidence to produce their
first data for scientific analysis. Although the detectors were still far from
their design sensitivity levels, the data can be used to place better upper
limits on the flux of gravitational waves incident on the earth than previous
direct measurements. This paper describes the instruments and the data in some
detail, as a companion to analysis papers based on the first data.Comment: 41 pages, 9 figures 17 Sept 03: author list amended, minor editorial
change
Analysis of LIGO data for gravitational waves from binary neutron stars
We report on a search for gravitational waves from coalescing compact binary
systems in the Milky Way and the Magellanic Clouds. The analysis uses data
taken by two of the three LIGO interferometers during the first LIGO science
run and illustrates a method of setting upper limits on inspiral event rates
using interferometer data. The analysis pipeline is described with particular
attention to data selection and coincidence between the two interferometers. We
establish an observational upper limit of 1.7 \times 10^{2}M_\odot$.Comment: 17 pages, 9 figure
Anisotropic flow of charged hadrons, pions and (anti-)protons measured at high transverse momentum in Pb-Pb collisions at TeV
The elliptic, , triangular, , and quadrangular, , azimuthal
anisotropic flow coefficients are measured for unidentified charged particles,
pions and (anti-)protons in Pb-Pb collisions at TeV
with the ALICE detector at the Large Hadron Collider. Results obtained with the
event plane and four-particle cumulant methods are reported for the
pseudo-rapidity range at different collision centralities and as a
function of transverse momentum, , out to GeV/.
The observed non-zero elliptic and triangular flow depends only weakly on
transverse momentum for GeV/. The small dependence
of the difference between elliptic flow results obtained from the event plane
and four-particle cumulant methods suggests a common origin of flow
fluctuations up to GeV/. The magnitude of the (anti-)proton
elliptic and triangular flow is larger than that of pions out to at least
GeV/ indicating that the particle type dependence persists out
to high .Comment: 16 pages, 5 captioned figures, authors from page 11, published
version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/186
Centrality dependence of charged particle production at large transverse momentum in Pb-Pb collisions at TeV
The inclusive transverse momentum () distributions of primary
charged particles are measured in the pseudo-rapidity range as a
function of event centrality in Pb-Pb collisions at
TeV with ALICE at the LHC. The data are presented in the range
GeV/ for nine centrality intervals from 70-80% to 0-5%.
The Pb-Pb spectra are presented in terms of the nuclear modification factor
using a pp reference spectrum measured at the same collision
energy. We observe that the suppression of high- particles strongly
depends on event centrality. In central collisions (0-5%) the yield is most
suppressed with at -7 GeV/. Above
GeV/, there is a significant rise in the nuclear modification
factor, which reaches for GeV/. In
peripheral collisions (70-80%), the suppression is weaker with almost independently of . The measured nuclear
modification factors are compared to other measurements and model calculations.Comment: 17 pages, 4 captioned figures, 2 tables, authors from page 12,
published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/284
Two-pion Bose-Einstein correlations in central Pb-Pb collisions at = 2.76 TeV
The first measurement of two-pion Bose-Einstein correlations in central Pb-Pb
collisions at TeV at the Large Hadron Collider is
presented. We observe a growing trend with energy now not only for the
longitudinal and the outward but also for the sideward pion source radius. The
pion homogeneity volume and the decoupling time are significantly larger than
those measured at RHIC.Comment: 17 pages, 5 captioned figures, 1 table, authors from page 12,
published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/388
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