A test of the QED process
e
+
e
−→
γγ(
γ) is reported. The data analysed were collected with the DELPHI detector in 1998 and 1999 at the highest energies achieved at LEP, reaching 202 GeV in the ...centre-of-mass. The total integrated luminosity amounts to 375.7 pb
−1. The differential and total cross-sections for the process
e
+
e
−→
γγ were measured, and found to be in agreement with the QED prediction. 95% confidence level (C.L.) lower limits on the QED cut-off parameters of
Λ
+>330 GeV and
Λ
−>320 GeV were derived. A 95% C.L. lower bound on the mass of an excited electron of 311 GeV/
c
2 (for
λ
γ
=1) was obtained. s-channel virtual graviton exchange was searched for, resulting in 95% C.L. lower limits on the string mass scale,
M
S
:
M
S
>713 GeV/
c
2 (
λ=1) and
M
S
>691 GeV/
c
2 (
λ=−1).
Muon pair production in the process \(e^+e^-\to e^+e^-\mu^+\mu^-\) is studied using the data taken at LEP1 (\(\sqrt{s}\simeq m_Z\)) with the DELPHI detector during the years 1992-1995. The ...corresponding integrated luminosity is 138.5 pb\(^{-1}\). The QED predictions have been tested over the whole \(Q^2\) range accessible at LEP1 (from several GeV\(^2/c^4\) to several hundred GeV\(^2/c^4\)) by comparing experimental distributions with distributions resulting from Monte Carlo simulations using various generators. Selected events are used to extract the leptonic photon structure function \(F_2^\gamma\). Azimuthal correlations are used to obtain information on additional structure functions, \(F_A^\gamma\) and \(F_B^\gamma\), which originate from interference terms of the scattering amplitudes. The measured ratios \(F_A^\gamma/F_2^\gamma\) and \(F_B^\gamma/F_2^\gamma\) are significantly different from zero and consistent with QED predictions.
A search for the supersymmetric partner of the goldstino, the sgoldstino
S, at LEP2 is presented. The production
Sγ followed by
S decay into two gluons or into two photons was studied at 189–202 GeV ...LEP centre-of-mass energies. No evidence for the
S production was found and limits on the
S mass corresponding to different theory parameters are given.
The DELPHI experiment at LEP has measured the inclusive charmless
B hadron decay branching ratio, the
B branching ratio into two charmed particles, and the total number of charmed particles per
B ...decay, using the hadronic Z data taken between 1992 and 1995. The results are extracted from a fit to the
b-tagging probability distribution based on the precise impact parameter measurements made using the microvertex detector. The inclusive charmless
B branching ratio, including
B decays into hidden charm (
c
c
̄
), is measured to be 0.033±0.021. The
B branching ratio into two open charmed particles is 0.136±0.042. The mean number of charmed particles per
B decay (including hidden charm) is 1.147±0.041. After subtracting the
B decay branching ratio into hidden charm, the charmless
B branching ratio is found to be 0.007±0.021, compatible with the Standard Model expectation. Models that predict an additional contribution to the charmless
B branching ratio of 0.037 or higher are excluded with at least 95% confidence.
Diffusion tensor imaging (DTI) enables non-invasive, cyto-architectural mapping of in vivo tissue microarchitecture through voxel-wise mathematical modeling of multiple magnetic resonance imaging ...(MRI) acquisitions, each differently sensitized to water diffusion. DTI computations are fundamentally estimation processes and are sensitive to noise and artifacts. Despite widespread adoption in the neuroimaging community, maintaining consistent DTI data quality remains challenging given the propensity for patient motion, artifacts associated with fast imaging techniques, and the possibility of hardware changes/failures. Furthermore, the quantity of data acquired per voxel, the non-linear estimation process, and numerous potential use cases complicate traditional visual data inspection approaches. Currently, quality inspection of DTI data has relied on visual inspection and individual processing in DTI analysis software programs (e.g. DTIPrep, DTI-studio). However, recent advances in applied statistical methods have yielded several different metrics to assess noise level, artifact propensity, quality of tensor fit, variance of estimated measures, and bias in estimated measures. To date, these metrics have been largely studied in isolation. Herein, we select complementary metrics for integration into an automatic DTI analysis and quality assurance pipeline. The pipeline completes in 24 hours, stores statistical outputs, and produces a graphical summary quality analysis (QA) report. We assess the utility of this streamlined approach for empirical quality assessment on 608 DTI datasets from pediatric neuroimaging studies. The efficiency and accuracy of quality analysis using the proposed pipeline is compared with quality analysis based on visual inspection. The unified pipeline is found to save a statistically significant amount of time (over 70%) while improving the consistency of QA between a DTI expert and a pool of research associates. Projection of QA metrics to a low dimensional manifold reveal qualitative, but clear, QA-study associations and suggest that automated outlier/anomaly detection would be feasible.
Searches for charginos, neutralinos and sleptons at LEP2 centre-of-mass energies from 130 GeV to 189 GeV have been used to set lower limits on the mass of the Lightest Supersymmetric Particle and ...other supersymmetric particles within the MSSM framework. R-parity conservation has been assumed. The lightest neutralino was found to be heavier than 32.3 GeV/
c
2 independent of the
m
0 value. The lightest chargino, the second-to-lightest neutralino, the next-to-heaviest neutralino, the heaviest neutralino, the sneutrino and the right-handed selectron were found to be heavier than 62.4 GeV/
c
2, 62.4 GeV/
c
2, 99.9 GeV/
c
2, 116.0 GeV/
c
2, 61.0 GeV/
c
2, and 87.0 GeV/
c
2, respectively. These limits do not depend on
m
0 or
M
2 and are valid for 1≤ tan
β≤40, in the
μ region where the lightest neutralino is the LSP. If the sneutrino is heavier than the chargino the lightest neutralino has to be heavier than 32.4 GeV/
c
2. The effects of mixings in the third family of sfermions on these limits are discussed. The confidence level of all limits given is 95%.
We described and validated a quantitative anatomical labeling protocol for extracting clinically relevant quantitative parameters for ventral hernias (VH) from routine computed tomography (CT) scans. ...This information was then used to predict the need for mesh bridge closure during ventral hernia repair (VHR).
A detailed anatomical labeling protocol was proposed to enable quantitative description of VH including shape, location, and surrounding environment (61 scans). Intra- and inter-rater reproducibilities were calculated for labeling on 18 and 10 clinically acquired CT scans, respectively. Preliminary clinical validation was performed by correlating 20 quantitative parameters derived from anatomical labeling with the requirement for mesh bridge closure at surgery (26 scans). Prediction of this clinical endpoint was compared with similar models fit on metrics from the semi-quantitative European Hernia Society Classification for Ventral Hernia (EHSCVH).
High labeling reproducibilities were achieved for abdominal walls (±2 mm in mean surface distance), key anatomical landmarks (±5 mm in point distance), and hernia volumes (0.8 in Cohen's kappa). 9 out of 20 individual quantitative parameters of hernia properties were significantly different between patients who required mesh bridge closure versus those in whom fascial closure was achieved at the time of VHR (p<0.05). Regression models constructed by two to five metrics presented a prediction with 84.6% accuracy for bridge requirement with cross-validation; similar models constructed by EHSCVH variables yielded 76.9% accuracy.
Reproducibility was acceptable for this first formal presentation of a quantitative image labeling protocol for VH on abdominal CT. Labeling-derived metrics presented better prediction of the need for mesh bridge closure than the EHSCVH metrics. This effort is intended as the foundation for future outcomes studies attempting to optimize choice of surgical technique across different anatomical types of VH.
Searches for pair production of supersymmetric particles under the assumption that
R-parity is not conserved are presented, based on data recorded by the DELPHI detector in 1998 from e
+e
− ...collisions at a centre-of-mass energy of 189 GeV. Only one
R-parity violating
LL
E
̄
term (i.e. one
λ coupling), which couples scalar leptons to leptons, is considered to be dominant at a time. Moreover, it is assumed that the strength of the
R-parity violating couplings is such that the lifetimes can be neglected. The search for pair production of neutralinos, charginos and sleptons has been performed for both direct
R-parity violating decays and indirect cascade decays. The results are in agreement with Standard Model expectations, and are used to update the constraints on the MSSM parameter values and the mass limits previously derived at
s
=183 GeV. The present 95% C.L. limits on supersymmetric particle masses are:
•
m
χ
̃
0
>
30 GeV/
c
2 and
m
χ
̃
±
>
94 GeV/
c
2;
•
m
ν
̃
>
76.5 GeV/
c
2 (direct and indirect decays);
•
m
ℓ
̃
R
>
83 GeV/
c
2 (indirect decay only).
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