498 research outputs found
A novel background reduction strategy for high level triggers and processing in gamma-ray Cherenkov detectors
Gamma ray astronomy is now at the leading edge for studies related both to
fundamental physics and astrophysics. The sensitivity of gamma detectors is
limited by the huge amount of background, constituted by hadronic cosmic rays
(typically two to three orders of magnitude more than the signal) and by the
accidental background in the detectors. By using the information on the
temporal evolution of the Cherenkov light, the background can be reduced. We
will present here the results obtained within the MAGIC experiment using a new
technique for the reduction of the background. Particle showers produced by
gamma rays show a different temporal distribution with respect to showers
produced by hadrons; the background due to accidental counts shows no
dependence on time. Such novel strategy can increase the sensitivity of present
instruments.Comment: 4 pages, 3 figures, Proc. of the 9th Int. Syposium "Frontiers of
Fundamental and Computational Physics" (FFP9), (AIP, Melville, New York,
2008, in press
Main Lobe Control of a Beam Tilting Antenna Array Laid on a Deformable Surface
The projection method (PM) is a simple and low-cost pattern recovery technique that already proved its effectiveness in retrieving the radiation properties of different types of arrays that change shape in time. However, when dealing with deformable beam-tilting arrays, this method requires to compute new compensating phase shifts every time that the main lobe is steered, since these shifts depend on both the deformation geometry and the steering angle. This tight requirement causes additional signal processing and complicates the prediction of the array behavior, especially if the deformation geometry is not a priori known: this can be an issue since the PM is mainly used for simple and low-cost systems. In this letter, we propose a simplification of this technique for beam-tilting arrays that requires only basic signal processing. In fact the phase shifts that we use are the sum of two components: one can be directly extracted from strain sensor data that measure surface deformation and the other one can be precomputed according to basic antenna theory. The effectiveness of our approach has been tested on two antennas: a 4 × 4 array (trough full-wave simulations and measurements) and on an 8 × 8 array (trough full-wave simulations) placed on a doubly wedge-shaped surface with a beam tilt up to 40 degrees
The MAGIC Experiment and Its First Results
With its diameter of 17m, the MAGIC telescope is the largest Cherenkov
detector for gamma ray astrophysics. It is sensitive to photons above an energy
of 30 GeV. MAGIC started operations in October 2003 and is currently taking
data. This report summarizes its main characteristics, its rst results and its
potential for physics.Comment: 6 pages, 3 figures, to be published in the Proceedings of the 6th
International Symposium ''Frontiers of Fundamental and Computational
Physics'' (FFP6), Udine (Italy), Sep. 26-29, 200
Modeling and design of a plasma-based transmit-array with beam scanning capabilities
Abstract This work presents the proof of concept of a novel plasma-based transmit-array antenna with beam scanning capabilities. The transmit-array operates above the GHz (precisely at 1.6 GHz) and is capable of steering its main lobe up to thirty degrees. A metallic half-wave dipole is used as the active element of the transmit-array, while twenty-five cylindrical plasma discharges are adopted to steer the beam of the antenna simply by turning them on or off. These passive elements are geometrically displaced in a triangular lattice. A customized two-steps optimization strategy is used to choose the best geometrical parameters of the array and to select the subset of plasma discharges that maximizes the gain of the antenna for each desired scanning angle. Towards this aim, a particle swarm optimization is first used to optimize the geometrical parameters of the array, and then a genetic algorithm is adopted to select the optimal subset of plasma discharges that need to be turned on to scan the beam towards different directions. The designed transmit-array was modeled in CST Microwave Studio, using realistic plasma parameters extrapolated from measurements of a fabricated plasma discharge prototype
Feasibility and Predictive Performance of a Triage System for Patients with Cancer During the COVID-19 Pandemic
Background: Triage procedures have been implemented to limit hospital access and minimize infection risk among patients with cancer during the coronavirus disease (COVID-19) outbreak. In the absence of prospective evidence, we aimed to evaluate the predictive performance of a triage system in the oncological setting. Materials and Methods: This retrospective cohort study analyzes hospital admissions to the oncology and hematology department of Udine, Italy, during the COVID-19 pandemic (March 30 to April 30, 2020). A total of 3,923 triage procedures were performed, and data of 1,363 individual patients were reviewed. Results: A self-report triage questionnaire identified 6% of triage-positive procedures, with a sensitivity of 66.7% (95% confidence interval [CI], 43.0%–85.4%), a specificity of 94.3% (95% CI, 93.5%–95.0%), and a positive predictive value of 5.9% (95% CI, 4.3%–8.0%) for the identification of patients who were not admitted to the hospital after medical review. Patients with thoracic cancer (odds ratio [OR], 1.69; 95% CI, 1.13–2.53, p =.01), younger age (OR, 1.52; 95% CI, 1.15–2.01, p <.01), and body temperature at admission ≥37°C (OR, 9.52; 95% CI, 5.44–16.6, p <.0001) had increased risk of positive triage. Direct hospital access was warranted to 93.5% of cases, a further 6% was accepted after medical evaluation, whereas 0.5% was refused at admission. Conclusion: A self-report questionnaire has a low positive predictive value to triage patients with cancer and suspected severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) symptoms. Differential diagnosis with tumor- or treatment-related symptoms is always required to avoid unnecessary treatment delays. Body temperature measurement improves the triage process's overall sensitivity, and widespread SARS-CoV-2 testing should be implemented to identify asymptomatic carriers. Implications for Practice: This is the first study to provide data on the predictive performance of a triage system in the oncological setting during the coronavirus disease outbreak. A questionnaire-based triage has a low positive predictive value to triage patients with cancer and suspected severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) symptoms, and a differential diagnosis with tumor- or treatment-related symptoms is mandatory to avoid unnecessary treatment delays. Consequently, adequate recourses should be reallocated for a triage implementation in the oncological setting. Of note, body temperature measurement improves the overall sensitivity of the triage process, and widespread testing for SARS-CoV-2 infection should be implemented to identify asymptomatic carriers
Comparison of water buffalo (Bubalus bubalis) vs Zebu-type intact males bovines in slaughter characteristics, carcass traits, cutability and longissimus palatability
Twenty-seven intact male water buffaloes of Murrah breeding (BUFFALOES) and 18 Zebu type bulls (CATTLE) were savannah-fed on the same ranch and slaughtered when they reached a desirable conformation to be compared in slaughter characteristics, carcass traits, cutability and meat palatability. Slaughter weight ranged 435 to 512kg for BUFFALOES and 375 to 494kg for CATTLE. Least square mean differences between species in percent head, cooler shrink, feet, blood and genitals were not significant (P>.05). BUFFALOES had significantly heavier hides, larger gastrointestinal tract and higher (P>.05) percentages of liveweight removed as organ fat. These body components are partly responsible for the significantly lower dressing percentages (- 6.5 %) of BUFFALOES vs CATTLE. Non-significant differences were found between species for total percentages of trimmed fat and bone, and percent yield (P>.05) of the most expensive (high valued, boneless) cuts. CATTLE yielded higher percentages (P<.05) of the medium-valued cuts (+1.39%) and the composite group of boneless (high and medium valued) cuts (+2.06%); whereas buffaloes exceeded (+.86%) cattle in the proportion of low-valued cuts (P<.05). Significant Specie x Carcass weight interactions were detected for some retail components. Longissimus steaks from CATTLE exhibited higher (P<.001) shear values (5.05kg vs 3.52kg)(P<.001) and lower (P>.05) overall tenderness ratings (4..3 vs 4.8). It was concluded that commercial disadvantages of BUFFALOES in dressing percent and cutability detected herein, could be overcome by designing marketing strategies promoting the buffalo meat as a high-quality product
External Fields as a Probe for Fundamental Physics
Quantum vacuum experiments are becoming a flexible tool for investigating
fundamental physics. They are particularly powerful for searching for new light
but weakly interacting degrees of freedom and are thus complementary to
accelerator-driven experiments. I review recent developments in this field,
focusing on optical experiments in strong electromagnetic fields. In order to
characterize potential optical signatures, I discuss various low-energy
effective actions which parameterize the interaction of particle-physics
candidates with optical photons and external electromagnetic fields.
Experiments with an electromagnetized quantum vacuum and optical probes do not
only have the potential to collect evidence for new physics, but
special-purpose setups can also distinguish between different particle-physics
scenarios and extract information about underlying microscopic properties.Comment: 12 pages, plenary talk at QFEXT07, Leipzig, September 200
First- and second-line treatment strategies for hormone-receptor (HR)-positive HER2-negative metastatic breast cancer: A real-world study
Background: Endocrine therapy (ET) plus cyclin-dependent-kinases 4/6 inhibitors (CDK4/6i) represents the standard treatment for luminal-metastatic breast cancer (MBC). However, prospective head-to-head comparisons are still lacking for 1st line (L) options, and it is still crucial to define the best strategy between 1st and 2nd L. Materials and methods: 717 consecutive luminal-MBC pts treated between 2008 and 2020 were analyzed at the Oncology Department of Aviano and Udine, Italy. Differences about survival outcomes (OS, PFS and PPS) were tested by log-rank test. The attrition rate (AR) between 1st and 2ndL was calculated. Results: At 1stL, pts were treated with ET (49%), chemotherapy (CT) (31%) and ET-CDKi (20%) while, at 2ndL, 33% received ET, 33% CT and 8% ET-CDKi. Overall AR was 10%, 7% for CT, 8% for ET and 17% for ET-CDKi. By multivariate analysis, 1stL ET-CDK4/6i showed a better mPFS1 and OS. Moreover, 2ndL ET-CDK4/6i demonstrated better mPFS2 compared to ET and CT. Notably, 1stL ET-CDKi resulted in higher mPFS than 2ndL ET-CDKi. Intriguingly, 1stL ET-CDK4/6i was associated with worse mPPS compared to CT and ET. Secondarily, 1stL ET-CDK4/6i followed by CT had worse OS compared to 1stL ET-CDK4/6i followed by ET. Notably, none of baseline characteristics at 2ndL influenced 2ndL treatment choice (ET vs. CT) after ET-CDKi. Conclusion: Our real-world data demonstrated that ET-CDKi represents the best option for 1stL luminal-MBC compared to ET and CT. Also, the present study pointed out that 2ndL ET, potentially combined with other molecules, could be a feasible option after CDK4/6i failure, postponing CT on later lines
The marine activities performed within the TOMO-ETNA experiment
The TOMO-ETNA experiment was planned in order to obtain a detailed geological and structural model of the continental and oceanic crust beneath Mt. Etna volcano and northeastern Sicily up to the Aeolian Islands (southern Italy), by integrating data from active and passive refraction and reflection seismic methodologies, magnetic and gravity surveys. This paper focuses on the marine activities performed within the experiment, which have been carried out in the Ionian and Tyrrhenian Seas, during three multidisciplinary oceanographic cruises, involving three research vessels (\u201cSarmiento de Gamboa\u201d, \u201cGalatea\u201d and \u201cAegaeo\u201d) belonging to different countries and institutions. During the offshore surveys about 9700 air-gun shots were produced to achieve a high-resolution seismic tomography through the wide-angle seismic refraction method, covering a total of nearly 2650 km of shooting tracks. To register ground motion, 27 ocean bottom seismometers were deployed, extending the inland seismic permanent network of the Istituto Nazionale di Geofisica e Vulcanologia (INGV) and a temporary network installed for the experiment. A total of 1410 km of multi-channel seismic reflection profiles were acquired to image the subsurface of the area and to achieve a 2D velocity model for each profile. Multibeam sonar and sub bottom profiler data were also collected. Moreover, a total of 2020 km of magnetic and 680 km of gravity track lines were acquired to compile magnetic and gravity anomaly maps offshore Mt. Etna volcano. Here, high-resolution images of the seafloor, as well as sediment and rock samples, were also collected using a remotely operated vehicle
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