93 research outputs found
Feshbach Resonances and Medium Effects in ultracold atomic Gases
We develop an effective low energy theory for multi-channel scattering of
cold atomic alkali atoms with particular focus on Feshbach resonances. The
scattering matrix is expressed in terms of observables only and the theory
allows for the inclusion of many-body effects both in the open and in the
closed channels.
We then consider the frequency and damping of collective modes for Fermi
gases and demonstrate how medium effects significantly increase the scattering
rate determining the nature of the modes. Our results obtained with no fitting
parameters are shown to compare well with experimental data.Comment: Presented at the 5th workshop on Critical Stability, Erice, Italy
13-17 October 2008. 8 pages, 3 figures. Figure caption correcte
Scaling Flows and Dissipation in the Dilute Fermi Gas at Unitarity
We describe recent attempts to extract the shear viscosity of the dilute
Fermi gas at unitarity from experiments involving scaling flows. A scaling flow
is a solution of the hydrodynamic equations that preserves the shape of the
density distribution. The scaling flows that have been explored in the
laboratory are the transverse expansion from a deformed trap ("elliptic flow"),
the expansion from a rotating trap, and collective oscillations. We discuss
advantages and disadvantages of the different experiments, and point to
improvements of the theoretical analysis that are needed in order to achieve
definitive results. A conservative bound based on the current data is that the
minimum of the shear viscosity to entropy density ration is that eta/s is less
or equal to 0.5 hbar/k_B.Comment: 32 pages, prepared for "BCS-BEC crossoverand the Unitary Fermi Gas",
Lecture Notes in Physics, W. Zwerger (editor), Fig. 5 corrected, note added;
final version, corrected typo in equ. 9
Accuracy of screening women at familial risk of breast cancer without a known gene mutation:individual patient data meta-analysis
Introduction Women with a strong family history of breast cancer (BC) and without a known gene mutation have an increased risk of developing BC. We aimed to investigate the accuracy of screening using annual mammography with or without magnetic resonance imaging (MRI) for these women outside the general population screening program. Methods An individual patient data (IPD) meta-analysis was conducted using IPD from six prospective screening trials that had included women at increased risk for BC: only women with a strong familial risk for BC and without a known gene mutation were included in this analysis. A generalised linear mixed model was applied to estimate and compare screening accuracy (sensitivity, specificity and predictive values) for annual mammography with or without MRI. Results There were 2226 women (median age: 41 years, interquartile range 35–47) with 7478 woman-years of follow-up, with a BC rate of 12 (95% confidence interval 9.3–14) in 1000 woman-years. Mammography screening had a sensitivity of 55% (standard error of mean [SE] 7.0) and a specificity of 94% (SE 1.3). Screening with MRI alone had a sensitivity of 89% (SE 4.6) and a specificity of 83% (SE 2.8). Adding MRI to mammography increased sensitivity to 98% (SE 1.8, P < 0.01 compared to mammography alone) but lowered specificity to 79% (SE 2.7, P < 0.01 compared with mammography alone). Conclusion In this population of women with strong familial BC risk but without a known gene mutation, in whom BC incidence was high both before and after age 50, adding MRI to mammography substantially increased screening sensitivity but also decreased its specificity.</p
Early improvements in signs and symptoms predict clinical response to baricitinib in patients with moderate-to-severe atopic dermatitis
Background
Early prediction of therapeutic response can optimize treatment strategies in atopic dermatitis (AD). Baricitinib is approved for moderate-to-severe AD in Europe, Japan and other countries.
Objectives
To identify early clinical improvements that can reliably predict a later clinical response to baricitinib in adults with moderate-to-severe AD.
Methods
Using data from one topical corticosteroid combination study [BREEZE-AD7 (NCT03733301)] and data pooled from two monotherapy studies [(BREEZE-AD1 (NCT03334396) and BREEZE-AD2 (NCT03334422)], we calculated the sensitivity and specificity, along with the positive predictive value (PPV) and negative predictive value (NPV), of predefined changes in single and combined clinical scores at weeks 2, 4 and 8, to predict clinical response at week 16. Clinical response was defined as ≥ 75% improvement in Eczema Area and Severity Index (EASI 75), ≥ 4-point improvement in Itch Numeric Rating Scale (Itch NRS ≥ 4), or a combination of both.
Results
Composite predictors had higher predictive accuracy for week 16 response outcomes than did single parameters. This was evident as early as week 4 for the combination of EASI 50 or Itch NRS ≥ 3 and of validated Investigator Global Assessment for AD (vIGA-AD) score ≤ 2 or Itch NRS ≥ 3 (sensitivity 87–100%; NPV 68–100%). The predictive accuracy of these composite clinical predictors for week 16 response outcomes was highest at week 8 (sensitivity 92–100%; NPV 80–100%). At both weeks 4 and 8, EASI 50 or Itch NRS ≥ 3 had higher sensitivity and NPV than did vIGA-AD score ≤ 2 or Itch NRS ≥ 3.
Conclusions
Improvement in signs and symptoms early during treatment with baricitinib 4 mg once daily predicts clinical response at week 16, providing a tool for dermatologists when choosing treatment strategies for patients with moderate-to-severe AD
Search for a W' boson decaying to a bottom quark and a top quark in pp collisions at sqrt(s) = 7 TeV
Results are presented from a search for a W' boson using a dataset
corresponding to 5.0 inverse femtobarns of integrated luminosity collected
during 2011 by the CMS experiment at the LHC in pp collisions at sqrt(s)=7 TeV.
The W' boson is modeled as a heavy W boson, but different scenarios for the
couplings to fermions are considered, involving both left-handed and
right-handed chiral projections of the fermions, as well as an arbitrary
mixture of the two. The search is performed in the decay channel W' to t b,
leading to a final state signature with a single lepton (e, mu), missing
transverse energy, and jets, at least one of which is tagged as a b-jet. A W'
boson that couples to fermions with the same coupling constant as the W, but to
the right-handed rather than left-handed chiral projections, is excluded for
masses below 1.85 TeV at the 95% confidence level. For the first time using LHC
data, constraints on the W' gauge coupling for a set of left- and right-handed
coupling combinations have been placed. These results represent a significant
improvement over previously published limits.Comment: Submitted to Physics Letters B. Replaced with version publishe
Measurement of the Lambda(b) cross section and the anti-Lambda(b) to Lambda(b) ratio with Lambda(b) to J/Psi Lambda decays in pp collisions at sqrt(s) = 7 TeV
The Lambda(b) differential production cross section and the cross section
ratio anti-Lambda(b)/Lambda(b) are measured as functions of transverse momentum
pt(Lambda(b)) and rapidity abs(y(Lambda(b))) in pp collisions at sqrt(s) = 7
TeV using data collected by the CMS experiment at the LHC. The measurements are
based on Lambda(b) decays reconstructed in the exclusive final state J/Psi
Lambda, with the subsequent decays J/Psi to an opposite-sign muon pair and
Lambda to proton pion, using a data sample corresponding to an integrated
luminosity of 1.9 inverse femtobarns. The product of the cross section times
the branching ratio for Lambda(b) to J/Psi Lambda versus pt(Lambda(b)) falls
faster than that of b mesons. The measured value of the cross section times the
branching ratio for pt(Lambda(b)) > 10 GeV and abs(y(Lambda(b))) < 2.0 is 1.06
+/- 0.06 +/- 0.12 nb, and the integrated cross section ratio for
anti-Lambda(b)/Lambda(b) is 1.02 +/- 0.07 +/- 0.09, where the uncertainties are
statistical and systematic, respectively.Comment: Submitted to Physics Letters
Search for new physics in events with opposite-sign leptons, jets, and missing transverse energy in pp collisions at sqrt(s) = 7 TeV
A search is presented for physics beyond the standard model (BSM) in final
states with a pair of opposite-sign isolated leptons accompanied by jets and
missing transverse energy. The search uses LHC data recorded at a
center-of-mass energy sqrt(s) = 7 TeV with the CMS detector, corresponding to
an integrated luminosity of approximately 5 inverse femtobarns. Two
complementary search strategies are employed. The first probes models with a
specific dilepton production mechanism that leads to a characteristic kinematic
edge in the dilepton mass distribution. The second strategy probes models of
dilepton production with heavy, colored objects that decay to final states
including invisible particles, leading to very large hadronic activity and
missing transverse energy. No evidence for an event yield in excess of the
standard model expectations is found. Upper limits on the BSM contributions to
the signal regions are deduced from the results, which are used to exclude a
region of the parameter space of the constrained minimal supersymmetric
extension of the standard model. Additional information related to detector
efficiencies and response is provided to allow testing specific models of BSM
physics not considered in this paper.Comment: Replaced with published version. Added journal reference and DO
Neoadjuvant chemoradiotherapy plus surgery versus active surveillance for oesophageal cancer: A stepped-wedge cluster randomised trial
Background: Neoadjuvant chemoradiotherapy (nCRT) plus surgery is a standard treatment for locally advanced oesophageal cancer. With this treatment, 29% of patients have a pathologically complete response in the resection specimen. This provides the rationale for investigating an active surveillance approach. The aim of this study is to assess the (cost-)effectiveness of active surveillance vs. standard oesophagectomy after nCRT for oesophageal cancer. Methods: This is a phase-III multi-centre, stepped-wedge cluster randomised controlled trial. A total of 300 patients with clinically complete response (cCR, i.e. no local or disseminated disease proven by histology) after nCRT will be randomised to show non-inferiority of active surveillance to standard oesophagectomy (non-inferiority margin 15%, intra-correlation coefficient 0.02, power 80%, 2-sided α 0.05, 12% drop-out). Patients will undergo a first clinical response evaluation (CRE-I) 4-6 weeks after nCRT, consisting of endoscopy with bite-on-bite biopsies of the primary tumour site and other suspected lesions. Clinically complete responders will undergo a second CRE (CRE-II), 6-8 weeks after CRE-I. CRE-II will include 18F-FDG-PET-CT, followed by endoscopy with bite-on-bite biopsies and ultra-endosonography plus fine needle aspiration of suspected lymph nodes and/or PET- positive lesions. Patients with cCR at CRE-II will be assigned to oesophagectomy (first phase) or active surveillance (second phase of the study). The duration of the first phase is determined randomly over the 12 centres, i.e., stepped-wedge cluster design. Patients in the active surveillance arm will undergo diagnostic evaluations similar to CRE-II at 6/9/12/16/20/24/30/36/48 and 60 months after nCRT. In this arm, oesophagectomy will be offered only to patients in whom locoregional regrowth is highly suspected or proven, without distant dissemination. The main study parameter is overall survival; secondary endpoints include percentage of patients who do not undergo surgery, quality of life, clinical irresectability (cT4b) rate, radical resection rate, postoperative complications, progression-free survival, distant dissemination rate, and cost-effectiveness. We hypothesise that active surveillance leads to non-inferior survival, improved quality of life and a reduction in costs, compared to standard oesophagectomy. Discussion: If active surveillance and surgery as needed after nCRT leads to non-inferior survival compared to standard oesophagectomy, this organ-sparing approach can be implemented as a standard of care
Towards a new image processing system at Wendelstein 7-X: From spatial calibration to characterization of thermal events
Wendelstein 7-X (W7-X) is the most advanced fusion experiment in the stellarator line and is aimed at proving that the stellarator concept is suitable for a fusion reactor. One of the most important issues for fusion reactors is the monitoring of plasma facing components when exposed to very high heat loads, through the use of visible and infrared (IR) cameras. In this paper, a new image processing system for the analysis of the strike lines on the inboard limiters from the first W7-X experimental campaign is presented. This system builds a model of the IR cameras through the use of spatial calibration techniques, helping to characterize the strike lines by using the information given by real spatial coordinates of each pixel. The characterization of the strike lines is made in terms of position, size, and shape, after projecting the camera image in a 2D grid which tries to preserve the curvilinear surface distances between points. The description of the strike-line shape is made by means of the Fourier Descriptors
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