7,169 research outputs found
Robust Foregrounds Removal for 21-cm Experiments
Direct detection of the Epoch of Reionization via the redshifted 21-cm line
will have unprecedented implications on the study of structure formation in the
early Universe. To fulfill this promise current and future 21-cm experiments
will need to detect the weak 21-cm signal over foregrounds several order of
magnitude greater. This requires accurate modeling of the galactic and
extragalactic emission and of its contaminants due to instrument chromaticity,
ionosphere and imperfect calibration. To solve for this complex modeling, we
propose a new method based on Gaussian Process Regression (GPR) which is able
to cleanly separate the cosmological signal from most of the foregrounds
contaminants. We also propose a new imaging method based on a maximum
likelihood framework which solves for the interferometric equation directly on
the sphere. Using this method, chromatic effects causing the so-called "wedge"
are effectively eliminated (i.e. deconvolved) in the cylindrical () power spectrum.Comment: Subbmited to the Proceedings of the IAUS333, Peering Towards Cosmic
Dawn, 4 pages, 2 figure
Trajectory Correction of the LHC Injection Transfer Lines TI 2 and TI 8
The LHC injection transfer lines TI 2 and TI 8 will transport very intense high-energy small-emittance proton beams over considerable distances. The relatively tight aperture requires a precise control of the trajectory. A detailed analysis of the trajectory excursions to be expected in the presence of various imperfections has been carried out. To stay within the given aperture a correction scheme is proposed in which two adjacent short straight sections out of every four are equipped with correctors. For both lines together this scheme requires 110 corrector elements. The maximum deflection per corrector remains below 65Ămrad. Corrector magnets and power supplies will be recuperated from LEP and adapted to their new function. The beam position monitors will use button-type electrodes which can also be recovered from LEP
Beam transfer to and Injection into LHC
Transfer of 450 GeV protons from SPS to LHC will be carried out through two new beam transfer lines with a length of about 2.8-km per line. One beam will use the existing SPS west extraction in LSS6 from where a new line will lead to the LHC injection near intersection 2. A new fast extraction facility in SPS LSS4 is needed for the other beam line which will lead to LHC intersection 8. Economy considerations have led to the decision to use classical magnets of compact design. A lot of components will be recuperated from closed down installations. The injection systems consist of horizontally deflecting Lambertson type septum magnets and vertically deflecting kickers. A careful control of the trajectory and the preservation of the very small emittance during transfer and injection are of key importance. Construction for the transfer lines will start in 1998 to allow first injection tests in 2003. The report describes the layout and optics design and the required performance of the main components
On the combination of omics data for prediction of binary outcomes
Enrichment of predictive models with new biomolecular markers is an important
task in high-dimensional omic applications. Increasingly, clinical studies
include several sets of such omics markers available for each patient,
measuring different levels of biological variation. As a result, one of the
main challenges in predictive research is the integration of different sources
of omic biomarkers for the prediction of health traits. We review several
approaches for the combination of omic markers in the context of binary outcome
prediction, all based on double cross-validation and regularized regression
models. We evaluate their performance in terms of calibration and
discrimination and we compare their performance with respect to single-omic
source predictions. We illustrate the methods through the analysis of two real
datasets. On the one hand, we consider the combination of two fractions of
proteomic mass spectrometry for the calibration of a diagnostic rule for the
detection of early-stage breast cancer. On the other hand, we consider
transcriptomics and metabolomics as predictors of obesity using data from the
Dietary, Lifestyle, and Genetic determinants of Obesity and Metabolic syndrome
(DILGOM) study, a population-based cohort, from Finland
Internal Modes and Magnon Scattering on Topological Solitons in 2d Easy-Axis Ferromagnets
We study the magnon modes in the presence of a topological soliton in a 2d
Heisenberg easy-axis ferromagnet. The problem of magnon scattering on the
soliton with arbitrary relation between the soliton radius R and the "magnetic
length" Delta_0 is investigated for partial modes with different values of the
azimuthal quantum numbers m. Truly local modes are shown to be present for all
values of m, when the soliton radius is enough large. The eigenfrequencies of
such internal modes are calculated analytically on limiting case of a large
soliton radius and numerically for arbitrary soliton radius. It is demonstrated
that the model of an isotropic magnet, which admits an exact analytical
investigation, is not adequate even for the limit of small radius solitons,
R<<Delta_0: there exists a local mode with nonzero frequency. We use the data
about local modes to derive the effective equation of soliton motion; this
equation has the usual Newtonian form in contrast to the case of the easy-plane
ferromagnet. The effective mass of the soliton is found.Comment: 33 pages (REVTeX), 12 figures (EPS
Testrun results from prototype fiber detectors for high rate particle tracking
A fiber detector concept has been realized allowing to registrate particles
within less than 100 nsec with a space point precision of about 0.1 mm at low
occupancy. Three full size prototypes have been build by different producers
and tested at a 3 GeV electron beam at DESY. After 3 m of light guides 8-10
photoelectrons were registrated by multichannel photomultipliers providing an
efficiency of more than 99%. Using all available data a resolution of 0.086 mm
was measured.Comment: 18 pages, 17 figure
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