Hasil untuk "astro-ph.EP"

Valenitn D. Ivanov

The searches for other life and for intelligence are fundamental problems that science faces today. Most searches so far have been focused on radio, but optical laser communication is an alternative, well suited for a ground-based observatory. A project to search for artificial laser communications with the current and future extreme multiplexity spectroscopic facilities that ESO may develop by the 2040s is outlined. The monochromatic light is a clearly identifiable technosignature. The enormous corollary outreach potential of this initiative is underlined.

Aleksey A. Shlyapnikov

The purpose of this work is to supplement the "Stars with solar-type activity" catalog with information about confirmed exoplanets and exoplanet candidates. To do this, cross-identification of the catalog stars with data from the NASA exoplanet archive was carried out. This article presents the distribution of the number of suspected stars with exoplanets by brightness, spectral type, amplitude of variability, as well as other statistical analysis data. Particular attention has been paid to the comparison of the periods of rotation of stars and the orbital periods of revolution of exoplanets around them. Analysis of the data suggests the need to change the previously determined types of variability in some stars.

David Garofalo

The link between black holes and star formation allows us to draw a connection between black holes and the places and times extraterrestrial intelligences (ETIs) had a greater chance of emerging. Within the context of the gap paradigm for black holes, we show that denser cluster environments that led to gas rich mergers and copious star formation were places less compatible on average with the emergence of ETIs compared to isolated elliptical galaxies by almost two orders of magnitude. The probability for ETIs peaked in these isolated environments around 6 billion years ago and cosmic downsizing shifted the likelihood of ETIs emerging to galaxies with weak black hole feedback, such as in spiral galaxies, at late times.

Katherine B Follette

This tutorial is an introduction to High-Contrast Imaging, a technique that enables astronomers to isolate light from faint planets and/or circumstellar disks that would otherwise be lost amidst the light of their host stars. Although technically challenging, high-contrast imaging allows for direct characterization of the properties of detected circumstellar sources. The intent of the article is to provide newcomers to the field a general overview of the terminology, observational considerations, data reduction strategies, and analysis techniques high-contrast imagers employ to identify, vet, and characterize planet and disk candidates.

Philip Horzempa

The Rigel concept calls for direct, on-surface, exploration of an exoplanet. This proposal will send a robot geologist to an exoplanet in the tau Ceti system. At a distance of 10 light-years, this may be the nearest system that includes a temperate rocky planet. As with Apollo, the Rigel project will provide a way to marshal efforts from many fields of engineering. The key to the Rigel concept is long-term development and management. A mission that lasts for a thousand years will require multi-generational oversight. Rigel may start out as a NASA project, but will later become a global endeavor. The construction of a robot ambassador from planet Earth can serve to unite the community of nations. It will bring out the best in us as we work on a project that will benefit our distant descendants.

J. L. Margot

Most planetary radar applications require recording of complex voltages at sampling rates of up to 20 MHz. I describe the design and implementation of a sampling system that has been installed at the Arecibo Observatory, Goldstone Solar System Radar, and Green Bank Telescope. After many years of operation, these data-taking systems have enabled the acquisition of hundreds of data sets, many of which still await publication.

J. Buatti, D. Pryma, A. Kiess et al.

Radiopharmaceutical therapy (RPT) is an area of projected growth and importance with several agents in clinical use, new agents in late-phase clinical trials, as well as many others under testing and development. This manuscript proposes a framework for developing pathways of care that can be broadly applied to all RPTs, representing the the current status of RPT, suggests foundational elements for many pathways of care for patients with cancer and concludes with areas in active development and the future horizon for RPT treatment centers. Developing a framework for patient-centered pathways of care is a critical step in establishing RPT as standard therapy for patients with a diverse spectrum of cancers. This expected increase in RPT treatment options will impact a much larger population of complex cancer patients. It will also require enhanced coordination and collaboration among appropriately qualified personnel with diverse expertise in image acquisition, image interpretation, quantitative imaging, dosimetry calculation, radiation QA and safety as well as oncology care and RPT-induced sequelae and response assessment. The essential role of this evolving RPT care team within multidisciplinary oncology care is a cornerstone of this framework for a patient-centered pathway of care for RPT. Given the status of current RPT practice and the horizon for future applications, this patient-centered pathway of care guidance is timely and should help inform future clinical RPT practice paradigms.

E. Troost, U. Nestle, P. Putora et al.

H. Shih, R. Rengan, S. Apisarnthanarax et al.

Aim/Objectives/Background: The American College of Radiology (ACR) and the American Society for Radiation Oncology (ASTRO) have jointly developed the following practice parameter for proton beam radiation therapy. Proton radiotherapy is the application of a high-energy proton beam to a patient in a clinical setting with therapeutic intent. Proton radiotherapy may permit improved therapeutic ratios with lower doses to sensitive normal structures and greater dose to target tumor tissues. Methods: A literature search was performed to identify published articles regarding clinical outcomes, reviews, quality assurance methodologies, and guidelines and standards for proton radiation therapy. Selected articles are referenced in the text. The following recommendations are based on firsthand experiences of multiple clinical authorities who employ proton therapy and have been peer reviewed by experts at different practicing institutions. Results: This practice parameter is developed to serve as a tool in the appropriate application of this evolving technology in the care of cancer patients or other patients with conditions where radiation therapy is indicated. It addresses clinical implementation of proton radiation therapy, including personnel qualifications, quality assurance standards, indications, and suggested documentation. Conclusions: This practice parameter is a tool to guide technical use of proton therapy and does not assess the relative clinical indication of proton radiotherapy when compared with other forms of radiotherapy, but to focus on the best practices required to deliver proton therapy safely and effectively, when clinically indicated. Costs of proton treatments are high, and the economic costs of proton radiotherapy may also need to be considered.

Kundan Kadam, Eduard Vorobyov, Zsolt Regály et al.

We conducted global hydrodynamic simulations of protoplanetary disk evolution with an adaptive Shakura-Sunyaev α prescription to represent the layered disk structure, and starting with the collapse phase of the molecular cloud. With the canonical values of model parameters, self-consistent dead zones formed at the scale of a few au. The instabilities associated with the dead zone and corresponding outbursts, similar to FUor eruptions, were also observed in the simulations.

D. Sher, D. Adelstein, G. Bajaj et al.

C. McCully, M. Tewes

C. Lauber, Michael Seifert, R. Bartenschlager et al.

RNA viruses are believed to have originated from a common ancestor, but how this ancestral genome evolved into the large variety of genomic architectures and viral proteomes we see today remains largely unknown. Tackling this question is hindered by the lack of universally conserved proteins other than the RNA-dependent RNA polymerase (RdRp) as well as a limited RNA virus sampling. The latter is still heavily biased towards relatively few viral lineages from a non-representative collection of hosts, which complicates studies aiming to reveal possible trajectories during the evolution of RNA virus genomes that are favored over others. We report the discovery of 11 highly divergent lineages of viruses with genomic architectures that resemble those of the astroviruses. These genomes were initially identified through a sequence homology search in more than 6600 plant transcriptome projects from the Sequence Read Archive (SRA) using astrovirus representatives as query. Seed-based viral genome assembly of unprocessed SRA data for several dozens of the most promising hits resulted in two viral genome sequences with full-length coding regions, nine partial genomes and a much larger number of short sequence fragments. Genomic and phylogenetic characterization of the 11 discovered viruses, which we coined plastroviruses (plant-associated astro-like viruses), showed that they are related to both astro- and potyviruses and allowed us to identify divergent Serine protease, RdRp and viral capsid domains encoded in the plastrovirus genome. Interestingly, some of the plastroviruses shared different features with potyviruses including the replacement of the catalytic Ser by a Cys residue in the protease active site. These results suggest that plastroviruses may have reached different points on an evolutionary trajectory from astro-like to poty-like genomes. A model how potyviruses might have emerged from (pl)astro-like ancestors in a multi-step process is discussed.

Y. Thakar, Rakesh Bhavsar, Mohit Swadia et al.

Abstract In present work electron induced processes with important astro-compounds found in the tholins of Titan are investigated. We report calculated total elastic cross sections Qel, total inelastic cross sections Qinel, total ionization cross sections Qion, total excitation cross sections ∑Qexc and total cross sections QT for hydrogen cyanide (HCN), cyanoacetylene (HCCCN), vinyl cyanide (CH2CHCN), methanimine (CH2NH) and ethanimine (CH3CHNH) on electron impact for energies from ionization threshold to 5 keV. We have employed the Spherical Complex Optical Potential (SCOP) formalism to investigate elastic as well as inelastic processes and used Complex Scattering Potential – ionization contribution (CSP-ic) method to derive ionization cross sections. In absence of any theoretical or experimental data of ionization cross sections except for HCN and HCCCN, we have computed Qion using the Binary- Encounter- Bethe (BEB) method for all these molecules and have found reasonable agreement. This is the maiden attempt to report various total cross sections for all these astro-molecules except HCN and HCCCN.

Dawit Tegbaru, Lisa C. Braverman, A. Zietman et al.

Transparency, openness, and reproducibility are important characteristics in scientific publishing. Although many researchers embrace these characteristics, data sharing has yet to become common practice. Nevertheless, data sharing is becoming an increasingly important topic among societies, publishers, researchers, patient advocates, and funders, especially as it pertains to data from clinical trials. In response, ASTRO developed a data policy and guide to best practices for authors submitting to its journals. ASTRO's data sharing policy is that authors should indicate, in data availability statements, if the data are being shared and if so, how the data may be accessed.

Y. Takei, S. Yasuda, K. Ishimura et al.

Abstract. The soft x-ray spectrometer (SXS) onboard ASTRO-H (named Hitomi after launch) is a microcalorimeter-type spectrometer, installed in a dewar to be cooled at 50 mK. The energy resolution of the SXS engineering model suffered from microvibration from cryocoolers mounted on the dewar. This is mitigated for the flight model (FM) by introducing vibration isolation systems between the cryocoolers and the dewar. The detector performance of the FM was verified before launch of the spacecraft in both ambient condition and thermal-vacuum condition, showing no detectable degradation in energy resolution. The in-orbit detector spectral performance and cryocooler cooling performance were also consistent with that on ground, indicating that the cryocoolers were not damaged by launch environment. The design and performance of the vibration isolation system along with the mechanism of how the microvibration could degrade the cryogenic detector is shown. Lessons learned from the development to mitigate unexpected issues are also described.

S. DeSnyder, K. Hunt, W. Dong et al.

Riccardo Petrolo, Yingyan Lin, E. Knightly

We propose ASTRO, a drone network that realizes three key features: (i) networked drones that coordinate in autonomous flight via software defined radios, (ii) off-grid tetherless flight without requiring a ground control station or air-to-ground network, and (iii) on-board machine learning missions based on on-drone sensor data shared among drones. We implement ASTRO and present a suite of proof-of-concept experiments based on a mission in which a network of ASTRO drones must find and track a mobile spectrum cheater.

K. Tamura, H. Kunieda, Y. Miyata et al.

Abstract. We designed depth-graded multilayers, so-called supermirrors, with platinum/carbon (Pt/C) layer pairs for the Hard X-Ray Telescope (HXT) that was on-board the sixth Japanese X-Ray Astronomy Satellite Hitomi (ASTRO-H). The HXT has multinested thin foil optics, and the grazing angles of the x-ray mirrors are 0.07 to 0.27 deg. Supermirrors for HXTs are designed to provide a broad energy response (up to 80 keV) for astronomical requests. Under practical boundary conditions, we establish a block method applying empirical rules to maximize the integrated reflectivity. We fabricated Pt/C supermirrors using a DC magnetron sputtering system. The reflectivity of the mirrors was measured in a synchrotron radiation facility, SPring-8. We describe the design method for the supermirrors and our results.

S. Yoshida, Mikio Miyaoka, K. Kanao et al.