3,680 results match your criteria Astronomical Journal[Journal]

Geo-heliocentric models and the Society of Jesus: from Clavius's resistance to Dechales's .

Ivana Gambaro

Ann Sci 2021 May 9:1-30. Epub 2021 May 9.

DAFIST, University of Genova, Genova, Italy.

In 1588 Tycho Brahe proposed a new cosmological system keeping a motionless Earth at the centre of the world. In the first half of the following century the reception of Tycho's model within the Society of Jesus was characterized by a strong resistance at the beginning, followed by a long and winding path, and then a good fortune, whereas heliocentric models were increasingly investigated in European observatories. In 1651 a Jesuit astronomer, Giovan Battista Riccioli, published the , an encyclopaedic synthesis of astronomical knowledge where the Earth's motions or rest were extensively discussed in order to prove the Earth's immobility. Read More

View Article and Full-Text PDF

Jets from MRC 0600-399 bent by magnetic fields in the cluster Abell 3376.

Nature 2021 May 5;593(7857):47-50. Epub 2021 May 5.

Division of Particle and Astrophysical Science, Nagoya University, Nagoya, Japan.

Galaxy clusters are known to harbour magnetic fields, the nature of which remains unresolved. Intra-cluster magnetic fields can be observed at the density contact discontinuity formed by cool and dense plasma running into hot ambient plasma, and the discontinuity exists near the second-brightest galaxy, MRC 0600-399, in the merging galaxy cluster Abell 3376 (redshift 0.0461). Read More

View Article and Full-Text PDF

Molecular dynamics reveals formation path of benzonitrile and other molecules in conditions relevant to the interstellar medium.

Proc Natl Acad Sci U S A 2021 May;118(19)

Fritz Haber Research Center for Molecular Dynamics, The Hebrew University of Jerusalem, 9190401 Jerusalem, Israel

Polycyclic aromatic hydrocarbons and polycyclic aromatic nitrogen heterocycles are believed to be widespread in different areas of the interstellar medium. However, the astronomical detection of specific aromatic molecules is extremely challenging. As a result, only a few aromatic molecules have been identified, and very little is known about how they are formed in different areas of the interstellar medium. Read More

View Article and Full-Text PDF

Finding Causal Mechanistic Drug-Drug Interactions from Observational Data.

AMIA Annu Symp Proc 2020 25;2020:363-372. Epub 2021 Jan 25.

IBM T. J. Watson Research Center, Yorktown Heights, NY, USA.

Many adverse drug reactions (ADRs) are caused by drug-drug interactions (DDIs), meaning they arise from concurrent use of multiple medications. Detecting DDIs using observational data has at least three major challenges: (1) The number of potential DDIs is astronomical; (2) Associations between drugs and ADRs may not be causal due to observed or unobserved confounding; and (3) Frequently co-prescribed drug pairs that each independently cause an ADR do not necessarily causally interact, where causal interaction means that at least some patients would only experience the ADR if they take both drugs. We address (1) through data mining algorithms pre-filtering potential interactions, and (2) and (3) by fitting causal interaction models adjusting for observed confounders and conducting sensitivity analyses for unobserved confounding. Read More

View Article and Full-Text PDF
January 2021

Three body photodissociation of the water molecule and its implications for prebiotic oxygen production.

Nat Commun 2021 04 30;12(1):2476. Epub 2021 Apr 30.

State Key Laboratory of Molecular Reaction Dynamics and Dalian Coherent Light Source, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China.

The provenance of oxygen on the Earth and other planets in the Solar System is a fundamental issue. It has been widely accepted that the only prebiotic pathway to produce oxygen in the Earth's primitive atmosphere was via vacuum ultraviolet (VUV) photodissociation of CO and subsequent two O atom recombination. Here, we provide experimental evidence of three-body dissociation (TBD) of HO to produce O atoms in both D and P states upon VUV excitation using a tunable VUV free electron laser. Read More

View Article and Full-Text PDF

Scalable photonic-based nulling interferometry with the dispersed multi-baseline GLINT instrument.

Nat Commun 2021 Apr 29;12(1):2465. Epub 2021 Apr 29.

Sydney Institute for Astronomy, School of Physics, The University of Sydney, Sydney, NSW, Australia.

Characterisation of exoplanets is key to understanding their formation, composition and potential for life. Nulling interferometry, combined with extreme adaptive optics, is among the most promising techniques to advance this goal. We present an integrated-optic nuller whose design is directly scalable to future science-ready interferometric nullers: the Guided-Light Interferometric Nulling Technology, deployed at the Subaru Telescope. Read More

View Article and Full-Text PDF

Disturbance Modelling for Minimum Variance Control in Adaptive Optics Systems Using Wavefront Sensor Sampled-Data.

Sensors (Basel) 2021 Apr 27;21(9). Epub 2021 Apr 27.

Departamento Electrónica, Universidad Técnica Federico Santa María (UTFSM), Av. España 1680, Valparaíso 2390123, Chile.

Modern large telescopes are built based on the effectiveness of adaptive optics systems in mitigating the detrimental effects of wavefront distortions on astronomical images. In astronomical adaptive optics systems, the main sources of wavefront distortions are atmospheric turbulence and mechanical vibrations that are induced by the wind or the instrumentation systems, such as fans and cooling pumps. The mitigation of wavefront distortions is typically attained via a control law that is based on an adequate and accurate model. Read More

View Article and Full-Text PDF

On Time Scales of Intrinsic Oscillations in the Climate System.

Entropy (Basel) 2021 Apr 13;23(4). Epub 2021 Apr 13.

Earth Insight, Hawthorn, VIC 3122, Australia.

Proxy temperature data records featuring local time series, regional averages from areas all around the globe, as well as global averages, are analyzed using the Slow Feature Analysis (SFA) method. As explained in the paper, SFA is much more effective than the traditional Fourier analysis in identifying slow-varying (low-frequency) signals in data sets of a limited length. We find the existence of a striking gap from ~1000 to about ~20,000 years, which separates intrinsic climatic oscillations with periods ranging from ~60 years to ~1000 years, from the longer time-scale periodicities (20,000 year+) involving external forcing associated with Milankovitch cycles. Read More

View Article and Full-Text PDF

X-ray quasi-periodic eruptions from two previously quiescent galaxies.

Nature 2021 Apr 28;592(7856):704-707. Epub 2021 Apr 28.

Leibniz-Institut für Astrophysik Potsdam (AIP), Potsdam, Germany.

Quasi-periodic eruptions (QPEs) are very-high-amplitude bursts of X-ray radiation recurring every few hours and originating near the central supermassive black holes of galactic nuclei. It is currently unknown what triggers these events, how long they last and how they are connected to the physical properties of the inner accretion flows. Previously, only two such sources were known, found either serendipitously or in archival data, with emission lines in their optical spectra classifying their nuclei as hosting an actively accreting supermassive black hole. Read More

View Article and Full-Text PDF

Towards a BRICS Astronomy Network.

An Acad Bras Cienc 2021 23;93(suppl 1):e20201759. Epub 2021 Apr 23.

Centro Brasileiro de Pesquisas Físicas, MCTI, Rua Dr. Xavier Sigaud, 150, Urca, 22290-180 Rio de Janeiro, RJ, Brazil.

View Article and Full-Text PDF

Towards a BRICS Optical Transient Network (BRICS-OTN).

An Acad Bras Cienc 2021 23;93(suppl 1):e20200917. Epub 2021 Apr 23.

College of Astronomy and Space Sciences, University of the Chinese Academy of Sciences, 100049, Beijing, China.

This paper is based on a proposal submitted for a BRICS astronomy flagship program, which was presented at the 2019 meeting of the BRICS Astronomy Working Group, held in Rio de Janeiro from 29 September to 2 October 2019. The future prospects for the detection and study of transient phenomena in the Universe heralds a new era in time domain astronomy. The case is presented for a dedicated BRICS-wide flagship program to develop a network of ground-based optical telescopes for an all-sky survey to detect short lived optical transients and to allow follow-up of multi-wavelength and multi-messenger transient objects. Read More

View Article and Full-Text PDF

An Overview of Some Latest Development in Chinese Astronomy.

An Acad Bras Cienc 2021 23;93(suppl 1):e20200808. Epub 2021 Apr 23.

National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Cao Yang District, 100101, Beijing, China.

We present brief highlights and updates on some newer projects, both in operation/construction and in preparation stages, of astronomical research on Mainland China, with an emphasis on those involving international collaborations. Limited by the scope of this paper, this sample is not meant to be uniform nor comprehensive, and in some cases it may not be fully up to date. For more specific and detailed information on these or other projects, we refer the readers to the official websites of these projects and those of the National Astronomical Observatories, Chinese Academy of Sciences. Read More

View Article and Full-Text PDF

The SiTian Project.

An Acad Bras Cienc 2021 23;93(suppl 1):e20200628. Epub 2021 Apr 23.

National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Rd, Chaoyang 100101, Beijing, China.

SiTian is an ambitious ground-based all-sky optical monitoring project, developed by the Chinese Academy of Sciences. The concept is an integrated network of dozens of 1-m-class telescopes deployed partly in China and partly at various other sites around the world. The main science goals are the detection, identification and monitoring of optical transients (such as gravitational wave events, fast radio bursts, supernovae) on the largely unknown timescales of less than 1 day; SiTian will also provide a treasure trove of data for studies of AGN, quasars, variable stars, planets, asteroids, and microlensing events. Read More

View Article and Full-Text PDF

Astronomical aspects of Group E-type complexes and implications for understanding ancient Maya architecture and urban planning.

Ivan Šprajc

PLoS One 2021 27;16(4):e0250785. Epub 2021 Apr 27.

Institute of Anthropological and Spatial Studies, Research Center of the Slovenian Academy of Sciences and Arts (ZRC SAZU), Ljubljana, Slovenia.

In the 1920s, during the first archaeological excavations at Uaxactún, Petén, Guatemala, an architectural complex named Group E was interpreted as an ancient Maya astronomical observatory, intended specifically for sighting the equinoctial and solstitial sunrises. In the following decades, a large number of architectural compounds with the same configuration have been found, most of them in the central lowlands of the Yucatan peninsula. The multiple hypotheses that have been proposed about the astronomical function of these complexes, commonly designated as E Groups, range from those attributing them a paramount role in astronomical observations to those that consider them merely allegorical or commemorative allusions to celestial cycles, without any observational use. Read More

View Article and Full-Text PDF

The novel Mechanical Ventilator Milano for the COVID-19 pandemic.

Phys Fluids (1994) 2021 Mar 23;33(3):037122. Epub 2021 Mar 23.

Camozzi Group S.p.A., Brescia BS 25126, Italy.

This paper presents the Mechanical Ventilator Milano (MVM), a novel intensive therapy mechanical ventilator designed for rapid, large-scale, low-cost production for the COVID-19 pandemic. Free of moving mechanical parts and requiring only a source of compressed oxygen and medical air to operate, the MVM is designed to support the long-term invasive ventilation often required for COVID-19 patients and operates in pressure-regulated ventilation modes, which minimize the risk of furthering lung trauma. The MVM was extensively tested against ISO standards in the laboratory using a breathing simulator, with good agreement between input and measured breathing parameters and performing correctly in response to fault conditions and stability tests. Read More

View Article and Full-Text PDF

First Detection of sub-PeV Diffuse Gamma Rays from the Galactic Disk: Evidence for Ubiquitous Galactic Cosmic Rays beyond PeV Energies.

Phys Rev Lett 2021 Apr;126(14):141101

Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China.

We report, for the first time, the long-awaited detection of diffuse gamma rays with energies between 100 TeV and 1 PeV in the Galactic disk. Particularly, all gamma rays above 398 TeV are observed apart from known TeV gamma-ray sources and compatible with expectations from the hadronic emission scenario in which gamma rays originate from the decay of π^{0}'s produced through the interaction of protons with the interstellar medium in the Galaxy. This is strong evidence that cosmic rays are accelerated beyond PeV energies in our Galaxy and spread over the Galactic disk. Read More

View Article and Full-Text PDF

Dark Energy Survey Year 1 Results: Cosmological Constraints from Cluster Abundances, Weak Lensing, and Galaxy Correlations.

Phys Rev Lett 2021 Apr;126(14):141301

Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.

We present the first joint analysis of cluster abundances and auto or cross-correlations of three cosmic tracer fields: galaxy density, weak gravitational lensing shear, and cluster density split by optical richness. From a joint analysis (4×2pt+N) of cluster abundances, three cluster cross-correlations, and the auto correlations of the galaxy density measured from the first year data of the Dark Energy Survey, we obtain Ω_{m}=0.305_{-0. Read More

View Article and Full-Text PDF

iBLAST: Incremental BLAST of new sequences via automated e-value correction.

PLoS One 2021 22;16(4):e0249410. Epub 2021 Apr 22.

Department of Computer Science, Virginia Tech, Blacksburg, VA, United States of America.

Search results from local alignment search tools use statistical scores that are sensitive to the size of the database to report the quality of the result. For example, NCBI BLAST reports the best matches using similarity scores and expect values (i.e. Read More

View Article and Full-Text PDF

Deep learning model to predict complex stress and strain fields in hierarchical composites.

Sci Adv 2021 Apr 9;7(15). Epub 2021 Apr 9.

Laboratory for Atomistic and Molecular Mechanics (LAMM), Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139, USA.

Materials-by-design is a paradigm to develop previously unknown high-performance materials. However, finding materials with superior properties is often computationally or experimentally intractable because of the astronomical number of combinations in design space. Here we report an AI-based approach, implemented in a game theory-based conditional generative adversarial neural network (cGAN), to bridge the gap between a material's microstructure-the design space-and physical performance. Read More

View Article and Full-Text PDF

Revolutionizing enzyme engineering through artificial intelligence and machine learning.

Emerg Top Life Sci 2021 Apr 9. Epub 2021 Apr 9.

Laboratory of Biocatalysis and Enzyme Engineering, Regional Centre for Biotechnology, Faridabad, Haryana 121001, India.

The combinatorial space of an enzyme sequence has astronomical possibilities and exploring it with contemporary experimental techniques is arduous and often ineffective. Multi-target objectives such as concomitantly achieving improved selectivity, solubility and activity of an enzyme have narrow plausibility under approaches of restricted mutagenesis and combinatorial search. Traditional enzyme engineering approaches have a limited scope for complex optimization due to the requirement of a priori knowledge or experimental burden of screening huge protein libraries. Read More

View Article and Full-Text PDF

Comprehensive rotational study and astronomical search for cyclopropanecarboxaldehyde.

Astron Astrophys 2021 Jan 15;645. Epub 2021 Jan 15.

Instituto de Física Fundamental (IFF-CSIC). Group of Molecular Astrophysics, C/Serrano 123, 28006 Madrid, Spain.

Context: At least a dozen molecules with a formyl group (HCO) have been observed to date in the interstellar medium (ISM), suggesting that other such species exist and remain to be discovered. However, there is still a lack of high-resolution spectroscopic data for simple molecular species of this type that could provide a basis for their detection.

Aims: Cyclopropanecarboxaldehyde, c-CHCHO, is a small molecule containing a formyl group and is therefore an interesting candidate for astrophysical detection. Read More

View Article and Full-Text PDF
January 2021

Enhanced x-ray emission coinciding with giant radio pulses from the Crab Pulsar.

Science 2021 04;372(6538):187-190

The Research Institute for Time Studies, Yamaguchi University, Yamaguchi 753-8511, Japan.

Giant radio pulses (GRPs) are sporadic bursts emitted by some pulsars that last a few microseconds and are hundreds to thousands of times brighter than regular pulses from these sources. The only GRP-associated emission outside of radio wavelengths is from the Crab Pulsar, where optical emission is enhanced by a few percentage points during GRPs. We observed the Crab Pulsar simultaneously at x-ray and radio wavelengths, finding enhancement of the x-ray emission by 3. Read More

View Article and Full-Text PDF

A study of CHN isomers in TMC-1: line by line detection of HCCCHCN.

Astron Astrophys 2021 Feb 12;646. Epub 2021 Feb 12.

Grupo de Astrofísica Molecular, Instituto de Física Fundamental, CSIC, C/ Serrano 123, 28006 Madrid, Spain.

We present Yebes 40m telescope observations of the three most stable CHN isomers towards the cyanopolyyne peak of TMC-1. We have detected 13 transitions from CHCN (A and E species), 16 lines from CHCCHCN, and 27 lines (a-type and b-type) from HCCCHCN. We thus provide a robust confirmation of the detection of HCCCHCN and CHCCHCN in space. Read More

View Article and Full-Text PDF
February 2021

Quality of life in young men with androgenetic alopecia: A mixed methods study.

J Cosmet Dermatol 2021 Apr 4. Epub 2021 Apr 4.

Department of Psychology, Faculty of Humanities and Social Sciences, University of Zagreb, Zagreb, Croatia.

Background: Androgenetic alopecia (AGA) is related to adverse psychological consequences in young men, which is further accentuated by the astronomical growth of the hair transplant industry. However, a deeper insight into AGA and its impact on young men are lacking in the literature. Moreover, its impact is currently measured with general dermatological health-related quality of life questionnaires. Read More

View Article and Full-Text PDF

Bandwidth correction of Swarm GPS carrier phase observations for improved orbit and gravity field determination.

GPS Solut 2021 9;25(2):70. Epub 2021 Mar 9.

Astronomical Institute, University of Bern, Sidlerstrasse 5, 3001 Bern, Switzerland.

Gravity fields derived from GPS tracking of the three Swarm satellites have shown artifacts near the geomagnetic equator, where the carrier phase tracking on the L2 frequency is unable to follow rapid ionospheric path delay changes due to a limited tracking loop bandwidth of only 0.25 Hz in the early years of the mission. Based on the knowledge of the loop filter design, an analytical approach is developed to recover the original L2 signal from the observed carrier phase through inversion of the loop transfer function. Read More

View Article and Full-Text PDF

Earth's carbon deficit caused by early loss through irreversible sublimation.

Sci Adv 2021 Apr 2;7(14). Epub 2021 Apr 2.

Department of Earth and Environmental Sciences, University of Minnesota, Minneapolis, MN 55455, USA.

Carbon is an essential element for life, but its behavior during Earth's accretion is not well understood. Carbonaceous grains in meteoritic and cometary materials suggest that irreversible sublimation, and not condensation, governs carbon acquisition by terrestrial worlds. Through astronomical observations and modeling, we show that the sublimation front of carbon carriers in the solar nebula, or the soot line, moved inward quickly so that carbon-rich ingredients would be available for accretion at 1 astronomical unit after the first million years. Read More

View Article and Full-Text PDF

Supernovae Detection with Fully Convolutional One-Stage Framework.

Sensors (Basel) 2021 Mar 9;21(5). Epub 2021 Mar 9.

School of Computer Science and Technology, Soochow University, Suzhou 215006, China.

A series of sky surveys were launched in search of supernovae and generated a tremendous amount of data, which pushed astronomy into a new era of big data. However, it can be a disastrous burden to manually identify and report supernovae, because such data have huge quantity and sparse positives. While the traditional machine learning methods can be used to deal with such data, deep learning methods such as Convolutional Neural Networks demonstrate more powerful adaptability in this area. Read More

View Article and Full-Text PDF

Recent increase in the occurrences of Christmas typhoons in the Western North Pacific.

Sci Rep 2021 Apr 1;11(1):7416. Epub 2021 Apr 1.

Typhoon Research Center, Jeju National University, Jeju, South Korea.

To imply the gravity of their impact on Christmas celebration, the term Christmas typhoon recently became more popular to refer to tropical cyclones (TC) in the Western North Pacific (WNP) during its less active season. The past 9 years from 2012 to 2020 saw more than 70% (210%) increases in Christmas typhoon occurrences in the WNP (Philippines). Furthermore, Mindanao Island, which is located in southern Philippines, has experienced an unprecedented 480% increase in TC passage in the same period. Read More

View Article and Full-Text PDF

Optical incoherent synthetic aperture imaging by superposition of phase-shifted optical transfer functions.

Opt Lett 2021 Apr;46(7):1712-1715

The concept of an optical incoherent synthetic aperture is widely used in astronomical interferometric telescopes. In this Letter, we propose a new, to the best of our knowledge, method to realize optical incoherent synthetic aperture imaging. The method is based on a superposition of optical transfer functions of incoherent imaging systems. Read More

View Article and Full-Text PDF