604 research outputs found
Shrinking a large dataset to identify variables associated with increased risk of Plasmodium falciparum infection in Western Kenya
Large datasets are often not amenable to analysis using traditional single-step approaches. Here, our general objective was to apply imputation techniques, principal component analysis (PCA), elastic net and generalized linear models to a large dataset in a systematic approach to extract the most meaningful predictors for a health outcome. We extracted predictors for Plasmodium falciparum infection, from a large covariate dataset while facing limited numbers of observations, using data from the People, Animals, and their Zoonoses (PAZ) project to demonstrate these techniques: data collected from 415 homesteads in western Kenya, contained over 1500 variables that describe the health, environment, and social factors of the humans, livestock, and the homesteads in which they reside. The wide, sparse dataset was simplified to 42 predictors of P. falciparum malaria infection and wealth rankings were produced for all homesteads. The 42 predictors make biological sense and are supported by previous studies. This systematic data-mining approach we used would make many large datasets more manageable and informative for decision-making processes and health policy prioritization
Global Search for New Physics with 2.0/fb at CDF
Data collected in Run II of the Fermilab Tevatron are searched for
indications of new electroweak-scale physics. Rather than focusing on
particular new physics scenarios, CDF data are analyzed for discrepancies with
the standard model prediction. A model-independent approach (Vista) considers
gross features of the data, and is sensitive to new large cross-section
physics. Further sensitivity to new physics is provided by two additional
algorithms: a Bump Hunter searches invariant mass distributions for "bumps"
that could indicate resonant production of new particles; and the Sleuth
procedure scans for data excesses at large summed transverse momentum. This
combined global search for new physics in 2.0/fb of ppbar collisions at
sqrt(s)=1.96 TeV reveals no indication of physics beyond the standard model.Comment: 8 pages, 7 figures. Final version which appeared in Physical Review D
Rapid Communication
Observation of Orbitally Excited B_s Mesons
We report the first observation of two narrow resonances consistent with
states of orbitally excited (L=1) B_s mesons using 1 fb^{-1} of ppbar
collisions at sqrt{s} = 1.96 TeV collected with the CDF II detector at the
Fermilab Tevatron. We use two-body decays into K^- and B^+ mesons reconstructed
as B^+ \to J/\psi K^+, J/\psi \to \mu^+ \mu^- or B^+ \to \bar{D}^0 \pi^+,
\bar{D}^0 \to K^+ \pi^-. We deduce the masses of the two states to be m(B_{s1})
= 5829.4 +- 0.7 MeV/c^2 and m(B_{s2}^*) = 5839.7 +- 0.7 MeV/c^2.Comment: Version accepted and published by Phys. Rev. Let
Measurement of the Bottom-Strange Meson Mixing Phase in the Full CDF Data Set
We report a measurement of the bottom-strange meson mixing phase \beta_s
using the time evolution of B0_s -> J/\psi (->\mu+\mu-) \phi (-> K+ K-) decays
in which the quark-flavor content of the bottom-strange meson is identified at
production. This measurement uses the full data set of proton-antiproton
collisions at sqrt(s)= 1.96 TeV collected by the Collider Detector experiment
at the Fermilab Tevatron, corresponding to 9.6 fb-1 of integrated luminosity.
We report confidence regions in the two-dimensional space of \beta_s and the
B0_s decay-width difference \Delta\Gamma_s, and measure \beta_s in [-\pi/2,
-1.51] U [-0.06, 0.30] U [1.26, \pi/2] at the 68% confidence level, in
agreement with the standard model expectation. Assuming the standard model
value of \beta_s, we also determine \Delta\Gamma_s = 0.068 +- 0.026 (stat) +-
0.009 (syst) ps-1 and the mean B0_s lifetime, \tau_s = 1.528 +- 0.019 (stat) +-
0.009 (syst) ps, which are consistent and competitive with determinations by
other experiments.Comment: 8 pages, 2 figures, Phys. Rev. Lett 109, 171802 (2012
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Tevatron-for-LHC Report of the QCD Working Group
The experiments at Run 2 of the Tevatron have each accumulated over 1 fb{sup -1} of high-transverse momentum data. Such a dataset allows for the first precision (i.e. comparisons between theory and experiment at the few percent level) tests of QCD at a hadron collider. While the Large Hadron Collider has been designed as a discovery machine, basic QCD analyses will still need to be performed to understand the working environment. The Tevatron-for-LHC workshop was conceived as a communication link to pass on the expertise of the Tevatron and to test new analysis ideas coming from the LHC community. The TeV4LHC QCD Working Group focused on important aspects of QCD at hadron colliders: jet definitions, extraction and use of Parton Distribution Functions, the underlying event, Monte Carlo tunes, and diffractive physics. This report summarizes some of the results achieved during this workshop
Saethre-Chotzen syndrome : cranofacial anomalies caused by genetic changes in the TWIST gene
In this thesis, one of the most frequently occurring and most variable craniosynostosis
syndromes was investigated; Saethre-Chotzen syndrome. Craniosynostosis is the premature
obliteration of cranial sutures in the developing embryo. It can also occur in the first few
months of life. Saethre-Chotzen syndrome is, besides craniosynostosis, characterized by
specific facial and limb abnormalities, of which the most frequently reported are ptosis,
prominent crus helicis, cutaneous syndactyly of digit 2 and 3 on both hands and feet, and
broad halluces. Saethre-Chotzen syndrome has been linked to the TWIST gene on
chromosome 7p21.1. Mutations in and variably sized deletions of this gene can be found in
patients with clinical features of Saethre-Chotzen syndrome. The latter, TWIST deletions,
often also include part of the surrounding chromosome 7p and are reported to be associated
with mental retardation. In Saethre-Chotzen patients, in whom neither a mutation nor a
deletion of TWIST had been found, the FGFR3 P250R mutation was in some cases detected.
This mutation has specifically been linked to Muenke syndrome that is characterized by unior
bicoronal synostosis and slight facial dysmorphology. However, a Saethre-Chotzen like
phenotype can also result from this mutation.
Because of the possible overlap of Saethre-Chotzen with Muenke syndrome, these syndromes
were studied in order to provide clinical criteria that discriminate between the two (chapter 4).
Many phenotypic features occur in both syndromes. In addition, although unicoronal
synostosis occurs slightly more frequently in Muenke syndrome, unicoronal and bicoronal
synostosis are seen in both syndromes. The discrimination between Saethre-Chotzen and
Muenke is often not made easily and the associated genes, TWIST and FGFR3, respectively,
are simultaneously tested for pathogenic m
W boson polarization measurement in the ttbar dilepton channel using the CDF II Detector
We present a measurement of boson polarization in top-quark decays in
events with decays to dilepton final states using of integrated luminosity in collisions collected by the
CDF II detector at the Tevatron. A simultaneous measurement of the fractions of
longitudinal () and right-handed () bosons yields the results
and . Combining this measurement
with our previous result based on single lepton final states, we obtain and . The results are consistent with standard
model expectation.Comment: Published in Phys. Lett.
Measurement of the Bs Lifetime in Fully and Partially Reconstructed Bs -> Ds- (phi pi-)X Decays in pbar-p Collisions at sqrt(s) = 1.96 TeV
We present a measurement of the Bs lifetime in fully and partially
reconstructed Bs -> Ds(phi pi)X decays in 1.3 fb-1 of pbar-p collisions at
sqrt(s) = 1.96 TeV collected by the CDF II detector at the Fermilab Tevatron.
We measure tau(Bs) = 1.518 +/- 0.041 (stat.) +/- 0.027 (syst.) ps. The ratio of
this result and the world average B0 lifetime yields tau(Bs)/tau(B0) = 0.99
+/-0.03, which is in agreement with recent theoretical predictions.Comment: submitted to Phys. Rev. Let
Observation of the structure in the Mass Spectrum in cays
The observation of the structure in decays produced in collisions at \sqrt{s}=1.96~\TeV is
reported with a statistical significance greater than 5 standard deviations. A
fit to the mass spectrum is performed assuming the presence of a
Breit-Wigner resonance. The fit yields a signal of resonance
events, and resonance mass and width of
4143.4^{+2.9}_{-3.0}(\mathrm{stat})\pm0.6(\mathrm{syst})~\MeVcc and
15.3^{+10.4}_{-6.1}(\mathrm{stat})\pm2.5(\mathrm{syst})~\MeVcc respectively.
The parameters of this resonance-like structure are consistent with values
reported from an earlier CDF analysis.Comment: 7 pages, 2 figures, submited to Phys. Rev. Let
Search for leptophobic Z ' bosons decaying into four-lepton final states in proton-proton collisions at root s=8 TeV
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