Search Our Scientific Publications & Authors

Nature 2020 Jul 1;583(7814):39-42. Epub 2020 Jul 1.

Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA.

The interiors of giant planets remain poorly understood. Even for the planets in the Solar System, difficulties in observation lead to large uncertainties in the properties of planetary cores. Exoplanets that have undergone rare evolutionary processes provide a route to understanding planetary interiors. Read More

J Chem Theory Comput 2020 Jun 30. Epub 2020 Jun 30.

The atmospheric reaction of HS with Cl has been re-investigated in order to check if, as previously suggested, only explicit dynamical computations can lead to an accurate evaluation of the reaction rate because of strong recrossing effects and the breakdown of the variational extension of transition state theory. For this reason, the corresponding potential energy surface has been thoroughly investigated, thus leading to an accurate characterization of all stationary points, whose energetics has been computed at the state of the art. To this end, coupled-cluster theory including up to quadruple excitations has been employed, together with the extrapolation to the complete basis set limit and also incorporating core-valence correlation, spin-orbit, and scalar relativistic effects as well as diagonal Born-Oppenheimer corrections. Read More

Nature 2020 Jun 24;582(7813):497-500. Epub 2020 Jun 24.

SUNY Stony Brook, Stony Brook, NY, USA.

AU Microscopii (AU Mic) is the second closest pre-main-sequence star, at a distance of 9.79 parsecs and with an age of 22 million years. AU Mic possesses a relatively rare and spatially resolved edge-on debris disk extending from about 35 to 210 astronomical units from the star, and with clumps exhibiting non-Keplerian motion. Read More

Phys Rev E 2020 May;101(5-1):051201

Lawrence Livermore National Laboratory, Livermore, California 94550, USA.

We discuss the experimental and modeling results for the x-ray heating and temperature of laboratory photoionized plasmas. A method is used to extract the electron temperature based on the analysis of transmission spectroscopy data that is independent of atomic kinetics modeling. The results emphasized the critical role of x-ray heating and radiation cooling in determining the energy balance of the plasma. Read More

Sensors (Basel) 2020 Jun 18;20(12). Epub 2020 Jun 18.

National Institute for Astrophysics (INAF), Catania Astrophysical Observatory, 95123 Catania, Italy.

In a recent paper, the authors discussed the feasibility study of an innovative technique based on the directionality of Cherenkov light produced in a transparent material to improve the signal to noise ratio in muon imaging applications. In particular, the method was proposed to help in the correct identification of incoming muons direction. After the first study by means of Monte Carlo simulations with Geant4, the first reduced scale prototype of such a detector was built and tested at the Department of Physics and Astronomy "E. Read More

Phys Rev Lett 2020 Jun;124(22):225001

Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany.

For more than 40 years, most astrophysical observations and laboratory studies of two key soft x-ray diagnostic 2p-3d transitions, 3C and 3D, in Fe XVII ions found oscillator strength ratios f(3C)/f(3D) disagreeing with theory, but uncertainties had precluded definitive statements on this much studied conundrum. Here, we resonantly excite these lines using synchrotron radiation at PETRA III, and reach, at a millionfold lower photon intensities, a 10 times higher spectral resolution, and 3 times smaller uncertainty than earlier work. Our final result of f(3C)/f(3D)=3. Read More

Phys Rev Lett 2020 Jun;124(22):221103

Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg, Germany.

Surface processes on cosmic solids in cold astrophysical environments lead to gas-phase depletion and molecular complexity. Most astrophysical models assume that the molecular ice forms a thick multilayer substrate, not interacting with the dust surface. In contrast, we present experimental results demonstrating the importance of the surface for porous grains. Read More

Phys Rev Lett 2020 May;124(21):211801

Maryland Center for Fundamental Physics, Department of Physics, University of Maryland, College Park, Maryland 20742, USA.

In this Letter, we investigate the effects of single derivative mixing in massive bosonic fields. In the regime of large mixing, we show that this leads to striking changes of the field dynamics, delaying the onset of classical oscillations and decreasing, or even eliminating, the friction due to Hubble expansion. We highlight this phenomenon with a few examples. Read More

Phys Rev Lett 2020 May;124(21):211301

Departamento de Física Teórica and IFIC, Universitat de València-CSIC. Doctor Moliner 50, 46100 Burjassot (València), Spain.

This work establishes a relation between chiral anomalies in curved spacetimes and the radiative content of the gravitational field. In particular, we show that a flux of circularly polarized gravitational waves triggers the spontaneous creation of photons with net circular polarization from the quantum vacuum. Using waveform catalogs, we identify precessing binary black holes as astrophysical configurations that emit such gravitational radiation and then solve the fully nonlinear Einstein's equations with numerical relativity to evaluate the net effect. Read More

Phys Rev Lett 2020 May;124(21):211101

Dipartimento di Fisica, "Sapienza" Università di Roma and Sezione INFN Roma1, Piazzale Aldo Moro 5, 00185 Roma, Italy.

Ultralight bosonic fields are compelling dark-matter candidates and arise in a variety of beyond standard model scenarios. These fields can tap energy and angular momentum from spinning black holes through superradiant instabilities, during which a macroscopic bosonic condensate develops around the black hole. Striking features of this phenomenon include gaps in the spin-mass distribution of astrophysical black holes and a continuous gravitational-wave (GW) signal emitted by the condensate. Read More

Nat Commun 2020 Jun 10;11(1):2942. Epub 2020 Jun 10.

Department of Physics, University of Wisconsin-Madison, Madison, WI, USA.

Energetic particle generation is an important component of a variety of astrophysical systems, from seed particle generation in shocks to the heating of the solar wind. It has been shown that magnetic pumping is an efficient mechanism for heating thermal particles, using the largest-scale magnetic fluctuations. Here we show that when magnetic pumping is extended to a spatially-varying magnetic flux tube, magnetic trapping of superthermal particles renders pumping an effective energization method for particles moving faster than the speed of the waves and naturally generates power-law distributions. Read More

Phys Rev Lett 2020 May;124(19):192702

Departamento de Aceleradores, Instituto Nacional de Investigaciones Nucleares, Apartado Postal 18-1027, Codigo Postal 11801, Mexico, D.F., Mexico.

Carbon and oxygen burning reactions, in particular, ^{12}C+^{12}C fusion, are important for the understanding and interpretation of the late phases of stellar evolution as well as the ignition and nucleosynthesis in cataclysmic binary systems such as type Ia supernovae and x-ray superbursts. A new measurement of this reaction has been performed at the University of Notre Dame using particle-γ coincidence techniques with SAND (a silicon detector array) at the high-intensity 5U Pelletron accelerator. New results for ^{12}C+^{12}C fusion at low energies relevant to nuclear astrophysics are reported. Read More

Phys Rev Lett 2020 May;124(19):192701

GANIL, CEA/DSM-CNRS/IN2P3, Caen F-14076, France.

The ^{12}C+^{12}C fusion reaction plays a critical role in the evolution of massive stars and also strongly impacts various explosive astrophysical scenarios. The presence of resonances in this reaction at energies around and below the Coulomb barrier makes it impossible to carry out a simple extrapolation down to the Gamow window-the energy regime relevant to carbon burning in massive stars. The ^{12}C+^{12}C system forms a unique laboratory for challenging the contemporary picture of deep sub-barrier fusion (possible sub-barrier hindrance) and its interplay with nuclear structure (sub-barrier resonances). Read More

Sci Rep 2020 May 22;10(1):8525. Epub 2020 May 22.

Institute for Industrial, Radiophysical and Environmental Safety, Universitat Politècnica de València, Camino de Vera, s/n, 46022, València, Spain.

For several years, reports have been published about fluctuations in measured radioactive decay time-series and in some instances linked to astrophysical as well as classical environmental influences. Anomalous behaviors of radioactive decay measurement and measurement of capacitance inside and outside a modified Faraday cage were documented by our group in previous work. In the present report, we present an in-depth analysis of our measurement with regard to possible correlations with space weather, i. Read More

Eur Phys J C Part Fields 2020 17;80(5):431. Epub 2020 May 17.

2Instituto de Física Corpuscular (IFIC), CSIC-Universitat de València, C/Catedrático José Beltrán 2, 46980 Paterna, Valencia Spain.

We present a study on the possibility of searching for long-lived supersymmetric partners with the MoEDAL experiment at the LHC. MoEDAL is sensitive to highly ionising objects such as magnetic monopoles or massive (meta)stable electrically charged particles. We focus on prospects of directly detecting long-lived sleptons in a phenomenologically realistic model which involves an intermediate neutral long-lived particle in the decay chain. Read More

Phys Rev E 2020 Apr;101(4-1):043208

York Plasma Institute, Department of Physics, University of York, York YO10 5DD, England, United Kingdom.

The formation of high energy density matter occurs in inertial confinement fusion, astrophysical, and geophysical systems. In this context, it is important to couple as much energy as possible into a target while maintaining high density. A recent experimental campaign, using buried layer (or "sandwich" type) targets and the ultrahigh laser contrast Vulcan petawatt laser facility, resulted in 500 Mbar pressures in solid density plasmas (which corresponds to about 4. Read More

Phys Rev E 2020 Apr;101(4-1):043212

Institute of Astronomy and Space Physics, Ciudad Universitaria, Buenos Aires 1428, Argentina and Physics Department, University of Buenos Aires, Ciudad Universitaria, Buenos Aires 1428, Argentina.

We derive the exact relation for the energy transfer in three-dimensional compressible two-fluid plasma turbulence. In the long-time limit, we obtain an exact law which expresses the scale-to-scale average energy flux rate in terms of two point increments of the fluid variables of each species, electric and magnetic field and current density, and puts a strong constraint on the turbulent dynamics. The incompressible single fluid and two-fluid limits and the compressible single fluid limit are recovered under appropriate assumption. Read More

Phys Rev Lett 2020 May;124(17):171101

National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo, 181-8588, Japan.

The astrophysical reach of current and future ground-based gravitational-wave detectors is mostly limited by quantum noise, induced by vacuum fluctuations entering the detector output port. The replacement of this ordinary vacuum field with a squeezed vacuum field has proven to be an effective strategy to mitigate such quantum noise and it is currently used in advanced detectors. However, current squeezing cannot improve the noise across the whole spectrum because of the Heisenberg uncertainty principle: when shot noise at high frequencies is reduced, radiation pressure at low frequencies is increased. Read More

Proc Math Phys Eng Sci 2020 Apr 22;476(2236):20190867. Epub 2020 Apr 22.

Princeton Plasma Physics Laboratory, Princeton, NJ 08543, USA.

Magnetic reconnection has been intensively studied in fully ionized plasmas. However, plasmas are often partially ionized in astrophysical environments. The interactions between the neutral particles and ionized plasmas might strongly affect the reconnection mechanisms. Read More

Phys Chem Chem Phys 2020 Jul 12;22(25):13880-13892. Epub 2020 May 12.

Synchrotron SOLEIL, L'Orme des Merisiers, St Aubin, BP 48, Gif sur Yvette, France.

We present the photoionization dynamics of the C buckminsterfullerene from threshold up to 14.0 eV recorded with VUV synchrotron radiation at the DESIRS beamline at the SOLEIL synchrotron. The recorded data is obtained using a double-imaging photoelectron photoion coincidence spectrometer and is presented as a two-dimensional photoelectron matrix which contains a wealth of spectroscopic data. Read More

Astrobiology 2020 May;20(5):580-582

INAF-Astronomical Observatory of Trieste, Trieste, Italy.

Phys Rev Lett 2020 Apr;124(14):145101

Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France.

Black holes are known to launch powerful relativistic jets and emit highly variable gamma radiation. How these jets are loaded with plasma remains poorly understood. Spark gaps are thought to drive particle acceleration and pair creation in the black-hole magnetosphere. Read More

Nat Commun 2020 Apr 24;11(1):1989. Epub 2020 Apr 24.

CEA, DAM, DIF, 91297, Arpajon, France.

Superdense plasmas widely exist in planetary interiors and astrophysical objects such as brown-dwarf cores and white dwarfs. How atoms behave under such extreme-density conditions is not yet well understood, even in single-species plasmas. Here, we apply thermal density functional theory to investigate the radiation spectra of superdense iron-zinc plasma mixtures at mass densities of ρ = 250 to 2000 g cm and temperatures of kT = 50 to 100 eV, accessible by double-shell-target implosions. Read More

Phys Rev Lett 2020 Apr;124(13):131101

Physics Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.

Because of the high energies and long distances to the sources, astrophysical observations provide a unique opportunity to test possible signatures of Lorentz invariance violation (LIV). Superluminal LIV enables the decay of photons at high energy. The high altitude water Cherenkov (HAWC) observatory is among the most sensitive gamma-ray instruments currently operating above 10 TeV. Read More

ACS Nano 2020 Jun 21;14(6):7152-7160. Epub 2020 Apr 21.

Department of Chemistry, Chungnam National University, Daejeon, 34134, Republic of Korea.

The astrophysical phenomenon of mimetic helical magnetic field ()-assisted self-assembly is herein introduced to build helical superstructures that display chiroptical properties. As a building block, magnetoplasmonic (MagPlas) Ag@FeO core-shell nanoparticles are used to guide plasmonic Ag nanoparticles onto a helical magnetic flux. The chirality of the assembled helical structures and tailored circular dichroism are successfully tuned in real time, and the handedness of the assembled structures is dynamically switched by the at the millisecond level, which is at least 6000-fold faster than other template-assisted methods. Read More

J Quant Spectrosc Radiat Transf 2020 Apr 13:107005. Epub 2020 Apr 13.

Crimean Astrophysical Observatory (CrAO RAS), Nauchnyj, 298409, Crimea.

Coronavirus virions have spherical shape surrounded by spike proteins. The coronavirus spike proteins are very effective molecular mechanisms, which provide the coronavirus entrance to the host cell. The number of these spikes is different; it dramatically depends on external conditions and determines the degree of danger of the virus. Read More

Mon Not R Astron Soc 2020 Apr 27;493(4):5273-5289. Epub 2020 Feb 27.

Research School of Astronomy and Astrophysics, The Australian National University, Canberra, ACT 2611, Australia.

We use the hydrodynamical simulation of our inner Galaxy presented in Armillotta et al. to study the gas distribution and kinematics within the Central Molecular Zone (CMZ). We use a resolution high enough to capture the gas emitting in dense molecular tracers such as NH and HCN, and simulate a time window of 50 Myr, long enough to capture phases during which the CMZ experiences both quiescent and intense star formation. Read More

Proc Natl Acad Sci U S A 2020 Apr 30;117(15):8398-8403. Epub 2020 Mar 30.

Department of Sociology, Princeton University, Princeton, NJ 08544;

How predictable are life trajectories? We investigated this question with a scientific mass collaboration using the common task method; 160 teams built predictive models for six life outcomes using data from the Fragile Families and Child Wellbeing Study, a high-quality birth cohort study. Despite using a rich dataset and applying machine-learning methods optimized for prediction, the best predictions were not very accurate and were only slightly better than those from a simple benchmark model. Within each outcome, prediction error was strongly associated with the family being predicted and weakly associated with the technique used to generate the prediction. Read More

Phys Rev Lett 2020 Mar;124(10):101302

Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai, 200240, China.

Chiral symmetry is maximally violated in weak interactions [1], and such microscopic asymmetries in the early Universe might leave observable imprints on astrophysical scales without violating the cosmological principle. In this Letter, we propose a helicity measurement to detect primordial chiral violation. We point out that observations of halo-galaxy angular momentum directions (spins), which are frozen in during the galaxy formation process, provide a fossil chiral observable. Read More

Phys Rev Lett 2020 Mar;124(10):105101

Astrophysical Institute, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium.

We use the Low Frequency Array (LOFAR) to probe the dynamics of the stepping process of negatively charged plasma channels (negative leaders) in a lightning discharge. We observe that at each step of a leader, multiple pulses of vhf (30-80 MHz) radiation are emitted in short-duration bursts (<10  μs). This is evidence for streamer formation during corona flashes that occur with each leader step, which has not been observed before in natural lightning and it could help explain x-ray emission from lightning leaders, as x rays from laboratory leaders tend to be associated with corona flashes. Read More

Phys Rev Lett 2020 Mar;124(10):101102

Fermi National Accelerator Laboratory, P. O. Box 500, Batavia, Illinois 60510, USA.

In recent years, many γ-ray sources have been identified, yet the unresolved component hosts valuable information on the faintest emission. In order to extract it, a cross-correlation with gravitational tracers of matter in the Universe has been shown to be a promising tool. We report here the first identification of a cross-correlation signal between γ rays and the distribution of mass in the Universe probed by weak gravitational lensing. Read More

Phys Rev Lett 2020 Mar;124(9):095101

Southwest Research Institute, San Antonio, Texas 78228, USA.

Electrostatic solitary wave (ESW)-a Debye-scale structure in space plasmas-was believed to accelerate electrons. However, such a belief is still unverified in spacecraft observations, because the ESW usually moves fast in spacecraft frame and its interior has never been directly explored. Here, we report the first measurements of an ESW's interior, by the Magnetospheric Multiscale mission located in a magnetotail reconnection jet. Read More

Phys Rev E 2020 Feb;101(2-1):022903

Skolkovo Institute of Science and Technology, 121205, Moscow, Russia.

We investigate numerically and analytically size-polydisperse granular mixtures immersed into a molecular gas. We show that the equipartition of granular temperatures of particles of different sizes is established; however, the granular temperatures significantly differ from the temperature of the molecular gas. This result is surprising since, generally, the energy equipartition is strongly violated in driven granular mixtures. Read More

Phys Rev E 2020 Feb;101(2-1):023205

Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom.

Currently there is considerable interest in creating scalable laboratory plasmas to study the mechanisms behind the formation and evolution of astrophysical phenomena such as Herbig-Haro objects and supernova remnants. Laboratory-scaled experiments can provide a well diagnosed and repeatable supplement to direct observations of these extraterrestrial objects if they meet similarity criteria demonstrating that the same physics govern both systems. Here, we present a study on the role of collision and cooling rates on shock formation using colliding jets from opposed conical wire arrays on a compact pulsed-power driver. Read More

Phys Rev E 2020 Feb;101(2-1):023211

Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey USA 08540.

A theoretically highly efficient mechanism, operating at high laser intensities and powers, is identified for spectral transferring huge laser energies to shorter ultraviolet and x-ray wavelengths. With megajoule laser energies currently available at near-optical wavelengths, this transfer would, in theory, enable megajoule x-ray lasers, a huge advance over the millijoules x-ray pulses produced now. In fact, enabling even kilojoule x-ray lasers would still be a fantastic advance, and a more likely achievable one, considering practical experimental inefficiencies. Read More

Phys Rev Lett 2020 Feb;124(8):081802

Department of Physics and Astronomy, Northwestern University, Evanston, Illinois 60208, USA.

keV-scale gauge-singlet fermions, when allowed to mix with the active neutrinos, are elegant dark matter (DM) candidates. They are produced in the early Universe via the Dodelson-Widrow mechanism and can be detected as they decay very slowly, emitting x-rays. In the absence of new physics, this hypothesis is virtually ruled out by astrophysical observations. Read More

J Basic Microbiol 2020 Jun 12;60(6):508-516. Epub 2020 Mar 12.

Astrophysical Sciences Division, Bhabha Atomic Research Centre, Mumbai, India.

Genetic diversity studies are crucial for understanding the genetic structure and evolutionary dynamics of fungal species and communities. Fungal genomes are often reshaped by their repetitive components such as transposable elements. These elements are key players in genomic rearrangements and are ideal targets for genetic diversity and evolutionary studies. Read More

Sci Rep 2020 Mar 4;10(1):4336. Epub 2020 Mar 4.

Nasir al-Din al-Tusi Shamakhi Astrophysical Observatory Azerbaijan, AZ, 1000, Pirqulu, Azerbaijan.

This article has been retracted. Read More

Rev Sci Instrum 2020 Feb;91(2):023307

Institute for Modeling Plasma, Atmospheres, and Cosmic Dust, Boulder, Colorado 80303, USA.

Permanently polarized Polyvinylidene Fluoride (PVDF) films have been used on a variety of spacecraft as in situ dust detectors to measure the size and spatial distributions of micron and sub-micron dust particles. The detectors produce a short electric pulse when impacted by a hypervelocity dust particle. The pulse amplitude depends on the mass and relative speed of the dust grain. Read More

Phys Rev Lett 2020 Feb;124(6):062502

KU Leuven, Intituut voor Kern-en Stralingsfysica, Celestijnenlaan 200D, 3001 Leuven, Belgium.

The nuclei below lead but with more than 126 neutrons are crucial to an understanding of the astrophysical r process in producing nuclei heavier than A∼190. Despite their importance, the structure and properties of these nuclei remain experimentally untested as they are difficult to produce in nuclear reactions with stable beams. In a first exploration of the shell structure of this region, neutron excitations in ^{207}Hg have been probed using the neutron-adding (d,p) reaction in inverse kinematics. Read More

Phys Rev Lett 2020 Feb;124(6):065101

Space Sciences Department, The Aerospace Corporation, El Segundo, California 90245, USA.

The first-order Fermi acceleration of electrons requires an injection of electrons into a mildly relativistic energy range. However, the mechanism of injection has remained a puzzle both in theory and observation. We present direct evidence for a novel stochastic shock drift acceleration theory for the injection obtained with Magnetospheric Multiscale observations at the Earth's bow shock. Read More

Astrobiology 2020 May 27;20(5):601-616. Epub 2020 Feb 27.

NASA Ames Research Center, MS 245-3, Moffett Field, California 94035.

Numerous laboratory studies of astrophysical ice analogues have shown that their exposure to ionizing radiation leads to the production of large numbers of new, more complex compounds, many of which are of astrobiological interest. We show here that the irradiation of astrophysical ice analogues containing HO, CHOH, CO, and NH yields quantities of hexamethylenetetramine-methanol (hereafter HMT-methanol; CNHO) that are easily detectible in the resulting organic residues. This molecule differs from simple HMT, which is known to be abundant in similar ice photolysis residues, by the replacement of a peripheral H atom with a CHOH group. Read More

Molecules 2020 Feb 22;25(4). Epub 2020 Feb 22.

Wellinq Medical, Van der Waals Park 22, 9351 VC Leek, The Netherlands.

This article discusses laser-induced laboratory-air plasma measurements and analysis of hydroxyl (OH) ultraviolet spectra. The computations of the OH spectra utilize line strength data that were developed previously and that are now communicated for the first time. The line strengths have been utilized extensively in interpretation of recorded molecular emission spectra and have been well-tested in laser-induced fluorescence applications for the purpose of temperature inferences from recorded data. Read More

Phys Rev Lett 2020 Feb;124(5):051103

III. Physikalisches Institut, RWTH Aachen University, D-52056 Aachen, Germany.

This Letter presents the results from pointlike neutrino source searches using ten years of IceCube data collected between April 6, 2008 and July 10, 2018. We evaluate the significance of an astrophysical signal from a pointlike source looking for an excess of clustered neutrino events with energies typically above ∼1  TeV among the background of atmospheric muons and neutrinos. We perform a full-sky scan, a search within a selected source catalog, a catalog population study, and three stacked Galactic catalog searches. Read More

Phys Rev Lett 2020 Feb;124(5):055002

Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA.

Tertiary modes in electrostatic drift-wave turbulence are localized near extrema of the zonal velocity U(x) with respect to the radial coordinate x. We argue that these modes can be described as quantum harmonic oscillators with complex frequencies, so their spectrum can be readily calculated. The corresponding growth rate γ_{TI} is derived within the modified Hasegawa-Wakatani model. Read More

Proc Math Phys Eng Sci 2020 Jan 8;476(2233):20190622. Epub 2020 Jan 8.

Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, CO 80309, USA.

The magnetorotational instability (MRI) occurs when a weak magnetic field destabilizes a rotating, electrically conducting fluid with inwardly increasing angular velocity. The MRI is essential to astrophysical disc theory where the shear is typically Keplerian. Internal shear layers in stars may also be MRI-unstable, and they take a wide range of profiles, including near-critical. Read More

J Phys Chem A 2020 Mar 3;124(10):2001-2013. Epub 2020 Mar 3.

Department of Chemistry, University of California, Berkeley, California 94720, United States.

Nitrogen-containing ions and molecules in the gas phase have been detected in non-Earth environments such as dark molecular clouds and more recently in the atmosphere of Saturn's moon Titan. These molecules may serve as precursors to larger heterocyclic structures that provide the foundation of complex biological molecules. On Titan, molecules of / 66 have been detected by the Cassini mission, and species of the empirical formula CHN may contribute to this signature. Read More

Sci Adv 2020 02 5;6(6):eaax3419. Epub 2020 Feb 5.

MRC Laboratory of Molecular Biology, Francis Crick Ave., Cambridge CB2 0QH, UK.

We advocate an integrative approach between laboratory experiments in prebiotic chemistry and geologic, geochemical, and astrophysical observations to help assemble a robust chemical pathway to life that can be reproduced in the laboratory. The cyanosulfidic chemistry scenario described here was developed by such an integrative iterative process. We discuss how it maps onto evolving planetary surface environments on early Earth and Mars and the value of comparative planetary evolution. Read More

Phys Rev Lett 2020 Jan;124(4):041102

Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109, USA.

We seek to achieve the holy grail of Bayesian inference for gravitational-wave astronomy: using deep-learning techniques to instantly produce the posterior p(θ|D) for the source parameters θ, given the detector data D. To do so, we train a deep neural network to take as input a signal + noise dataset (drawn from the astrophysical source-parameter prior and the sampling distribution of detector noise), and to output a parametrized approximation of the corresponding posterior. We rely on a compact representation of the data based on reduced-order modeling, which we generate efficiently using a separate neural-network waveform interpolant [A. Read More

Sci Rep 2020 Feb 13;10(1):2507. Epub 2020 Feb 13.

Aston Institute of Photonic Technologies, Aston University, Birmingham, UK.

In hydrodynamics, vortex generation upon the transition from smooth laminar flows to turbulence is generally accompanied by increased dissipation. However, vortices in the plane can provide transport barriers and decrease losses, as it happens in numerous geophysical, astrophysical flows and in tokamaks. Photon interactions with matter can affect light transport in ways resembling fluid dynamics. Read More