1,786 research outputs found
Neutrinoless Double Beta Decay Search with Ge: Status and Prospect with LEGEND
The search for neutrinoless double beta () decay is the best
way to test lepton number violation and Majorana nature of neutrinos. One of
the most promising techniques to discover decay is by
operating High-Purity Ge detectors enriched in Ge. The current
generation of Ge experiments, GERDA and MAJORANA, lead the field in the
achieved energy resolution and ultra-low background. These are two of the most
important characteristics for sensitive searches of this undiscovered decay.
The next generation of decay experiments requires more mass
and further reduction of backgrounds to maximize the discovery potential.
Building on the successes of GERDA and MAJORANA, the LEGEND collaboration has
been formed to pursue a tonne-scale Ge experiment, with a discovery
potential projected to be a half-life beyond 10^{28} years. The collaboration
aims to develop a phased experimental program, starting with a 200 kg
measurement by repurposing the existing Gerda infrastructure.Comment: Contribution to the 2019 EW session of the 54th Rencontres de
Moriond, 6 pages, 7 figure
Polariton-polariton scattering in microcavities: A microscopic theory
We apply the fermion commutation technique for composite bosons to
polariton-polariton scattering in semiconductor planar microcavities.
Derivations are presented in a simple and physically transparent fashion. A
procedure of orthogonolization of the initial and final two-exciton state
wavefunctions is used to calculate the effective scattering matrix elements and
the scattering rates. We show how the bosonic stimulation of the scattering
appears in this full fermionic approach whose equivalence to the bosonization
method is thus demonstrated in the regime of low exciton density. We find an
additional contribution to polariton-polariton scattering due to the exciton
oscillator strength saturation, which we analyze as well. We present a theory
of the polariton-polariton scattering with opposite spin orientations and show
that this scattering process takes place mainly via dark excitonic states.
Analytical estimations of the effective scattering amplitudes are given.Comment: Theoretical paper on polariton-polariton scattering in planar
microcavities. The new version contains a slightly modified abstract and a
revised introduction. Typos have been corrected wherever spotted. 16 page
The Collaborative Development of New CFD Methods Adapted for Tilt Rotor Aircraft in the HiPerTilt Project
No abstract available
Is contrast-enhanced US alternative to spiral CT in the assessment of treatment outcome of radiofrequency ablation in hepatocellular carcinoma?
Purpose: The present study was conducted to assess the efficacy of contrast-enhanced ultrasound with low mechanical index in evaluating the response of percutaneous radiofrequency ablation treatment of hepatocellular carcinoma by comparing it with 4-row spiral computed tomography. Materials and Methods: 100 consecutive patients (65 men and 35 women; age range: 62 – 76 years) with solitary hepatocellular carcinomas (mean lesion diameter: 3.7cm± 1.1cm SD) underwent internally cooled radiofrequency ablation. Therapeutic response was evaluated at one month after the treatment with triple-phasic contrast-enhanced spiral CT and low-mechanical index contrast-enhanced ultrasound following bolus injection of 2.4 ml of Sonovue (Bracco, Milan). 60 out of 100 patients were followed up for another 3 months. Contrast-enhanced sonographic studies were reviewed by two blinded radiologists in consensus. Sensitivity, specificity, NPV and PPV of contrast-enhanced ultrasound examination were determined. Results: After treatment, contrast-enhanced ultrasound identified persistent signal enhancement in 24 patients (24%), whereas no intratumoral enhancement was detected in the remaining 76 patients (76%). Using CT imaging as gold standard, the sensitivity, specificity, NPV, and PPV of contrast enhanced ultrasound were 92.3% (95% CI = 75.9 – 97.9%), 100% (95% CI = 95.2 – 100%), 97.4% (95% CI = 91.1 – 99.3%), and 100% (95% CI = 86.2 – 100%). Conclusion: Contrast-enhanced ultrasound with low mechanical index using Sonovue is a feasible tool in evaluating the response of hepatocellular carcinoma to radiofrequency ablation. Accuracy is comparable to 4-row spiral CT
Optimum Filter Synthesis with DPLMS Method for Energy Reconstruction
Optimum filters are granted increasing recognition as valuable tools for
parametric estimation in many scientific and technical fields. The DPLMS
method, introduced some twenty years ago, is effective among the synthesis
algorithms since it derives the optimum filters directly from the experimental
signal and noise waveforms. Two new extensions of the DPLMS method are here
presented. The first one speeds up the synthesis phase and improves the energy
estimation by synthesizing optimum filters with automatically designed flat-top
length. The second one improves the quality of parameter estimation in
multi-channel systems by taking advantage of the inter-channel noise
correlation properties. The theoretical and functional aspects behind the DPLMS
method for optimum filter synthesis are first recalled and illustrated in more
detail. The two new DPLMS extensions are subsequently introduced from the
theoretical viewpoint and more thoroughly considered from the applicative
perspective. The DPLMS optimum filters have been applied first to simulated
signals with various amounts and characteristics of superimposed noise and then
to the experimental waveforms acquired from a solid-state Ge detector. The
results obtained are considered from both the absolute viewpoint and in
comparison with those of more traditional, suboptimal filters. The results
demonstrate the effectiveness of the two new DPLMS extensions. For
single-channel energy estimations, the optimum filters provide comparatively
better results than the other filters. The DPLMS multi-channel optimum filters
further enhance the quality of the estimations, compared to single-channel
optimum filters, with non-negligible inter-channel noise correlation. The
effectiveness and robustness of the DPLMS method in synthesizing high-quality
filters for energy estimation will be tested soon within leading-edge
multi-channel physics experiments.Comment: 15 pages, 13 figure
Genomics knowledge and attitudes among European public health professionals. Results of a cross-sectional survey
Background The international public health (PH) community is debating the opportunity to incorporate genomic technologies into PH practice. A survey was conducted to assess attitudes of the European Public Health Association (EUPHA) members towards their role in the implementation of public health genomics (PHG), and their knowledge and attitudes towards genetic testing and the delivery of genetic services. Methods EUPHA members were invited via monthly newsletter and e-mail to take part in an online survey from February 2017 to January 2018. A descriptive analysis of knowledge and attitudes was conducted, along with a univariate and multivariate analysis of their determinants. Results Five hundred and two people completed the questionnaire, 17.9% were involved in PHG activities. Only 28.9% correctly identified all medical conditions for which there is (or not) evidence for implementing genetic testing; over 60% thought that investing in genomics may divert economic resources from social and environmental determinants of health. The majority agreed that PH professionals may play different roles in incorporating genomics into their activities. Better knowledge was associated with positive attitudes towards the use of genetic testing and the delivery of genetic services in PH (OR = 1.48; 95% CI 1.01–2.18). Conclusions Our study revealed quite positive attitudes, but also a need to increase awareness on genomics among European PH professionals. Those directly involved in PHG activities tend to have a more positive attitude and better knowledge; however, gaps are also evident in this group, suggesting the need to harmonize practice and encourage greater exchange of knowledge among professionals
Thymomas: a review.
Thymomas are neoplasma of thymic epithelial cells. They may be benign or malignant and may
associate with locai ìnvasiveness and paraneoplastic diseases. Myasthenia gravis is often
associated with thymomas, bui this is not thè rule. Several classifications have been proposed:
some of them follow thè histopathological findings (Rosai and Levine, Snover, Marino and Muller-
Hermelink classification), other emphasizes thè clinic-pathological stage (Masaoka, Verley and
Hollmann stadiation). One third of thymomas is asymptomatic. Diagnosis is made often by plain
X-ray and confirmed by Computed Tomography or fine needle biopsy. Surgery is effective in 100%
of noninvasive cases and in 58% of invasive ones. Radio and chemotherapy are recommended
only in advanced or inoperable stages
PANEV: an R package for a pathway-based network visualization
BACKGROUND: During the last decade, with the aim to solve the challenge of post-genomic and transcriptomic data mining, a plethora of tools have been developed to create, edit and analyze metabolic pathways. In particular, when a complex phenomenon is considered, the creation of a network of multiple interconnected pathways of interest could be useful to investigate the underlying biology and ultimately identify functional candidate genes affecting the trait under investigation. RESULTS: PANEV (PAthway NEtwork Visualizer) is an R package set for gene/pathway-based network visualization. Based on information available on KEGG, it visualizes genes within a network of multiple levels (from 1 to n) of interconnected upstream and downstream pathways. The network graph visualization helps to interpret functional profiles of a cluster of genes. CONCLUSIONS: The suite has no species constraints and it is ready to analyze genomic or transcriptomic outcomes. Users need to supply the list of candidate genes, specify the target pathway(s) and the number of interconnected downstream and upstream pathways (levels) required for the investigation. The package is available at https://github.com/vpalombo/PANEV
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