Hasil untuk "astro-ph.EP"

S. Lutz, L. Berk, E. Chang et al.

G. Videtic, J. Donington, M. Giuliani et al.

David Garfinkle, Alberto G. Rojo

Planets have maximum radii close to that of Jupiter. Qualitatively, the reason for this maximum size is that, as one adds mass, the force of gravity becomes sufficiently strong to cause the radius to decrease. We show that this effect can be understood quantitatively using a simple variational principle very similar to that used to compute the size of the hydrogen atom.

Scott C. Morgan, K. Hoffman, D. Loblaw et al.

PURPOSE The aim of this guideline is to present recommendations regarding moderately hypofractionated (240-340 cGy per fraction) and ultrahypofractionated (500 cGy or more per fraction) radiation therapy for localized prostate cancer. METHODS AND MATERIALS The American Society for Radiation Oncology convened a task force to address 8 key questions on appropriate indications and dose-fractionation for moderately and ultrahypofractionated radiation therapy, as well as technical issues, including normal tissue dose constraints, treatment volumes, and use of image guided and intensity modulated radiation therapy. Recommendations were based on a systematic literature review and created using a predefined consensus-building methodology and Society-approved tools for grading evidence quality and recommendation strength. RESULTS Based on high-quality evidence, strong consensus was reached for offering moderate hypofractionation across risk groups to patients choosing external beam radiation therapy. The task force conditionally recommends ultrahypofractionated radiation may be offered for low- and intermediate-risk prostate cancer but strongly encourages treatment of intermediate-risk patients on a clinical trial or multi-institutional registry. For high-risk patients, the task force conditionally recommends against routine use of ultrahypofractionated external beam radiation therapy. With any hypofractionated approach, the task force strongly recommends image guided radiation therapy and avoidance of nonmodulated 3-dimensional conformal techniques. CONCLUSIONS Hypofractionated radiation therapy provides important potential advantages in cost and convenience for patients, and these recommendations are intended to provide guidance on moderate hypofractionation and ultrahypofractionation for localized prostate cancer. The limits in the current evidentiary base-especially for ultrahypofractionation-highlight the imperative to support large-scale randomized clinical trials and underscore the importance of shared decision making between clinicians and patients.

Scott C. Morgan, K. Hoffman, D. Loblaw et al.

PURPOSE The aim of this guideline is to present recommendations regarding moderately hypofractionated (240-340 cGy per fraction) and ultrahypofractionated (500 cGy or more per fraction) radiation therapy for localized prostate cancer. METHODS AND MATERIALS The American Society for Radiation Oncology convened a task force to address 8 key questions on appropriate indications and dose-fractionation for moderately and ultrahypofractionated radiation therapy, as well as technical issues, including normal tissue dose constraints, treatment volumes, and use of image guided and intensity modulated radiation therapy. Recommendations were based on a systematic literature review and created using a predefined consensus-building methodology and Society-approved tools for grading evidence quality and recommendation strength. RESULTS Based on high-quality evidence, strong consensus was reached for offering moderate hypofractionation across risk groups to patients choosing external beam radiation therapy. The task force conditionally recommends ultrahypofractionated radiation may be offered for low- and intermediate-risk prostate cancer but strongly encourages treatment of intermediate-risk patients on a clinical trial or multi-institutional registry. For high-risk patients, the task force conditionally recommends against routine use of ultrahypofractionated external beam radiation therapy. With any hypofractionated approach, the task force strongly recommends image guided radiation therapy and avoidance of nonmodulated 3-dimensional conformal techniques. CONCLUSIONS Hypofractionated radiation therapy provides important potential advantages in cost and convenience for patients, and these recommendations are intended to provide guidance on moderate hypofractionation and ultrahypofractionation for localized prostate cancer. The limits in the current evidentiary base-especially for ultrahypofractionation-highlight the imperative to support large-scale randomized clinical trials and underscore the importance of shared decision making between clinicians and patients.

N. Burgio, L. Cretara, M. Corcione et al.

Purpose The AstroBio Cube Satellite (ABCS) will deploy within the inner Van Allen belt on the Vega C Maiden Flight launch opportunity of the European Space Agency. At this altitude, ABCS will experience radiation doses orders of magnitude greater than in low earth orbit, where CubeSats usually operate. The paper aims to estimate the irradiation effect on the ABCS payload in the orbital condition, their possible mitigation designing shielding solutions and performs a preliminary representativity simulation study on the ABCS irradiation with fission neutron at the TAPIRO (TAratura Pila Rapida Potenza 0) nuclear research reactor facility at ENEA. Methods We quantify the contributions of geomagnetically trapped particles (electron and proton), Galactic Cosmic Rays (GCR ions), Solar energetic particle within the ABCS orbit using the ESA’s SPace ENVironment information system. FLUKA (Fluktuierende Kaskade—Fluctuating Cascade) code models the ABCS interaction with the orbital source. Results We found a shielding solution of the weight of 300 g constituted by subsequent layers of tungsten, resins, and aluminium that decreases on average the 20% overall dose rate relative to the shielding offered by the only satellite’s structure. Finally, simulations of neutron irradiation of the whole ABCS structure within the TAPIRO’s thermal column cavity show that a relatively short irradiation time is requested to reach the same level of 1 MeV neutron Silicon equivalent damage of the orbital source. Conclusions The finding deserves the planning of a future experimental approach to confirm the TAPIRO’s performance and establish an irradiation protocol for testing aerospatial electronic components.

M. Harkenrider, K. Albuquerque, D. Brown et al.

PURPOSE This practice parameter aims to detail the processes, qualifications of personnel, patient selection, equipment, patient and personnel safety, documentation, and quality control and improvement necessary for an HDR brachytherapy program. METHODS AND MATERIALS This practice parameter was revised collaboratively by the American College of Radiology (ACR), the American Brachytherapy Society (ABS), and the American Society for Radiation Oncology (ASTRO). RESULTS Brachytherapy is a radiotherapeutic modality in which radionuclide or electronic sources are used to deliver a radiation dose at a distance of up to a few centimeters by surface, intracavitary, intraluminal, or interstitial application. Brachytherapy alone or combined with external beam radiotherapy plays an important role in the management and treatment of patients with cancer. High-dose-rate (HDR) brachytherapy uses radionuclides, such as iridium-192, at dose rates of ≥12 Gy/hr to a designated target point or volume, and it is an important treatment for a variety of malignant and benign conditions. Its use allows for application of high doses of radiation to defined target volumes with relative sparing of adjacent critical structures. CONCLUSIONS HDR brachytherapy requires detailed attention to personnel, equipment, patient and personnel safety, and continuing staff education. Coordination between the radiation oncologist and treatment planning staff and effective quality assurance procedures are important components of successful HDR brachytherapy programs.

H. Ejiri

Fundamental properties of neutrinos are investigated by studying double beta decays ( β β -decays), while atro-neutrino nucleo-syntheses and astro-neutrino productions are investigated by studying inverse beta decays (inverse β-decays) induced by astro-neutrinos. Neutrino nuclear responses for these β β and β-decays are crucial for these neutrino studies in nuclei. This reports briefly perspectives on experimental studies of neutrino nuclear responses (square of nuclear matrix element) for β β -decays and astro-neutrinos by using nuclear and leptonic (muon) charge-exchange reactions

J. Chino, C. Annunziata, S. Beriwal et al.

Samuel J. Goodman

I present WISEA J052305.94-015356.1 as a new candidate extremely metal-poor T subdwarf (esdT), based on its distinctive infrared colours and high proper motion ($\sim500\ $mas/yr). Spectroscopic follow-up is now needed to confirm it is a member of this newly discovered class of substellar objects.

L. Jacobs, E. D. du Preez, F. Fairer-Wessels

ABSTRACT Tourism is regarded as a key sector through which to bring about sustainable development in rural areas. A suitable product offering should be identified that matches the rural area’s unique resources with market demand. The Karoo Rural Node in South Africa’s unique landscape coupled with hosting astronomy sites of global importance presents the ideal opportunity to develop Astro Tourism as niche offering. This paper explores the region’s state of readiness to harness this potential through describing existing visitors’ travel behaviour, experiences and expectations, alongside views from supply side stakeholders. Mixed methodology presents evaluations at the hand of an Importance Performance and a SOAR Analysis depicting the state of readiness. The paper describes how a unique experience such as Astro Tourism can be regarded as viable mechanism to bring about sustainable development in a rural context.

D. Thomson, David A. Palma, M. Guckenberger et al.

Purpose Because of the unprecedented disruption of health care services caused by the COVID-19 pandemic, the American Society of Radiation Oncology (ASTRO) and the European Society for Radiotherapy and Oncology (ESTRO) identified an urgent need to issue practice recommendations for radiation oncologists treating head and neck cancer (HNC) in a time of limited resources and heightened risk for patients and staff. Methods and Materials A panel of international experts from ASTRO, ESTRO, and select Asia-Pacific countries completed a modified rapid Delphi process. Topics and questions were presented to the group, and subsequent questions were developed from iterative feedback. Each survey was open online for 24 hours, and successive rounds started within 24 hours of the previous round. The chosen cutoffs for strong agreement (≥80%) and agreement (≥66%) were extrapolated from the RAND methodology. Two pandemic scenarios, early (risk mitigation) and late (severely reduced radiation therapy resources), were evaluated. The panel developed treatment recommendations for 5 HNC cases. Results In total, 29 of 31 of those invited (94%) accepted, and after a replacement 30 of 30 completed all 3 surveys (100% response rate). There was agreement or strong agreement across a number of practice areas, including treatment prioritization, whether to delay initiation or interrupt radiation therapy for intercurrent SARS-CoV-2 infection, approaches to treatment (radiation dose-fractionation schedules and use of chemotherapy in each pandemic scenario), management of surgical cases in event of operating room closures, and recommended adjustments to outpatient clinic appointments and supportive care. Conclusions This urgent practice recommendation was issued in the knowledge of the very difficult circumstances in which our patients find themselves at present, navigating strained health care systems functioning with limited resources and at heightened risk to their health during the COVID-19 pandemic. The aim of this consensus statement is to ensure high-quality HNC treatments continue, to save lives and for symptomatic benefit.

B. Moeller, E. Balagamwala, Aileen B Chen et al.

PURPOSE To revise the recommendation on the use of concurrent chemotherapy (CC) with palliative thoracic external beam radiation therapy (EBRT) made in the original 2011 American Society for Radiation Oncology guideline on palliative thoracic radiation for lung cancer. METHODS AND MATERIALS Based on a systematic PubMed search showing new evidence for this key question, the task force felt an update was merited. Guideline recommendations were created using a predefined consensus-building methodology supported by American Society for Radiation Oncology-approved tools for grading evidence quality and recommendation strength. RESULTS Although few randomized clinical trials address the question of CC combined with palliative thoracic EBRT for non-small cell lung cancer (NSCLC), a strong consensus was reached among the task force on recommendations for incurable stage III and IV NSCLC. For patients with stage III NSCLC deemed unsuitable for curative therapy but who are (1) candidates for chemotherapy, (2) have an Eastern Cooperative Oncology Group PS of 0 to 2, and (3) have a life expectancy of at least 3 months, administration of a platinum-containing chemotherapy doublet concurrently with moderately hypofractionated palliative thoracic radiation therapy is recommended over treatment with either modality alone. For patients with stage IV NSCLC, routine use of concurrent thoracic chemoradiation is not recommended. CONCLUSIONS Optimal palliation of patients with incurable NSCLC requires coordinated interdisciplinary care. Recent data establish a rationale for CC with palliative thoracic EBRT for a well-defined subset of patients with incurable stage III NSCLC. For all other patients with incurable NSCLC, data remain insufficient to support this treatment approach.

Anthony Mallama

The mean visual magnitude of OneWeb satellites at the standard satellite distance of 1,000 km is 7.18 +/-0.03 . When this value is adjusted to the nominal 1,200 km altitude of a OneWeb satellite in orbit it corresponds to magnitude 7.58 which is an indication of the mean brightness at zenith. The OneWeb satellites are fainter than the original Starlink satellites at a common distance. Preliminary data on the new and dimmer VisorSat design for Starlink suggests that they are still brighter than OneWeb at the satellites' respective operational altitudes.

Philip Horzempa

This is a mission to explore the surface of Venus from low altitudes. The Calypso Venus Scout consists of a high-altitude balloon and a instrumented Descent Module (DM). The DM is deployed to an altitude of 10-25 km by means of a Tether where it obtains images, with meter and centimeter scale resolution, and rough IR spectra. It is reeled-in after several hours for a "cool down" cycle, then deployed again. The balloon remains at high-altitude with no need to be fortified to survive high-T and high-P of Venus' lower atmosphere.

Scott Tremaine

Some quadruple star systems in the hierarchical 2+2 configuration exhibit orbit-orbit resonances between the two compact binaries. We show that the most important resonances occur at period ratios of 1:1, 3:2 and 2:1. We describe the conditions required for capture and show that they can be satisfied at the 3:2 and 2:1 resonances in binaries that migrate significantly in semimajor axis after circularization, probably through magnetic braking or gravitational radiation.

A. Bellini, J. Anderson, L. Bedin et al.

We have constructed the most comprehensive catalog of photometry and proper motions ever assembled for a globular cluster (GC). The core of ωCen has been imaged over 650 times through WFC3's UVIS and IR channels for the purpose of detector calibration. There exist from 4 to over 60 exposures through each of 26 filters stretching continuously from F225W in the UV to F160W in the infrared. Furthermore, the 11 yr baseline between these data and a 2002 ACS survey has allowed us to more than double the proper-motion accuracy and triple the number of well-measured stars compared to our previous groundbreaking effort. This totally unprecedented complete spectral coverage of over 470,000 stars within the cluster’s core, from the tip of the red giant branch down to the white dwarfs, provides the best astro-photometric observational database yet to understand the multiple-population phenomenon in any GC. In this first paper of the series, we describe in detail the data-reduction processes and deliver the astro-photometric catalog to the astronomical community.

R. Kelley, H. Akamatsu, P. Azzarello et al.

Benjamin Monreal, Dominic Oddo, Christian Rodriguez

The Wide Aperture Exoplanet Telescope (WAET) is a new ground-based optical telescope layout with an extremely asymmetric aperture, which results in new exoplanet imaging reach at very low cost. We suggest that hWAET, a 100x2 telescope, can be built for $150M in the 2020s, and >300m versions merit further R&D.

Jason T. Wright

The search for life beyond the Solar System-a major part of the Planetary Systems thematic area of the Astro2020 Decadal process-includes the search for technological life. Although financial support for such searches at the NSF and NASA and in past decadal surveys has been weak to nonexistent, recent advances in astrobiology, astrophysics, and advances in technical capability make searches for technosignatures a compelling theme for 2020-2030 and beyond.