36,958 results match your criteria Astronomy & Astrophysics[Journal]


Chemical composition of rainwater under two events of aerosol transport: A Saharan dust outbreak and wildfires.

Sci Total Environ 2020 May 6;734:139202. Epub 2020 May 6.

Department of Physics, IMARENAB, University of León, León, Spain. Electronic address:

A one-year campaign of joint sampling of aerosols and precipitation, carried out in León, Spain, allowed to study the impact of two special events that affected the air quality in the north of the country, on rainfall in the city: a period with wildfires and a Saharan dust intrusion. The wildfires that occurred in northern Portugal and northwestern Spain in August 2016 affected the chemistry of rainfall on 15 August 2016, causing an increase in concentrations of NH, Na, Cl, K, Mg, Ca, SO and NO and in the concentrations of organic acids, which was reflected in the levels of soluble and insoluble organic carbon. This led to acidification of rainwater (pH = 4. Read More

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http://dx.doi.org/10.1016/j.scitotenv.2020.139202DOI Listing

Multisite cell- and neural-dynamics-resolving deep brain imaging in freely moving mice with implanted reconnectable fiber bundles.

J Biophotonics 2020 May 27. Epub 2020 May 27.

Physics Department, International Laser Center, M.V. Lomonosov Moscow State University, Moscow, Russia.

We demonstrate a reconnectable implantable ultraslim fiber-optic microendoscope that integrates a branching fiber bundle (BFB) with gradient-index fiber lenses, enabling a simultaneous fluorescence imaging of individual cells in distinctly separate brain regions, including brain structures as distant as the neocortex and hippocampus. We show that fluorescence images of individual calcium-indicator-expressing neurons in the brain of freely moving transgenic mice can be recorded, via the implanted BFB probe, in parallel with time- and cell-resolved traces of calcium signaling, thus enabling correlated circuit-dynamics studies at -multiple sites within the brain of freely moving animals. This article is protected by copyright. Read More

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http://dx.doi.org/10.1002/jbio.202000081DOI Listing

Surface-orientation- and ligand-dependent quenching of the spin magnetic moment of Co porphyrins adsorbed on Cu substrates.

Phys Chem Chem Phys 2020 May 27. Epub 2020 May 27.

Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany.

Porphyrin molecules are particularly interesting candidates for spintronic applications due to their bonding flexibility, which allows to modify their properties substantially by the addition or transformation of ligands. Here, we investigate the electronic and magnetic properties of cobalt octaethylporphyrin (CoOEP), deposited on copper substrates with two distinct crystallographic surface orientations, Cu(100) and Cu(111), with X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD). A significant magnetic moment is present in the Co ions of the molecules deposited on Cu(100), but it is completely quenched on Cu(111). Read More

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http://dx.doi.org/10.1039/d0cp00854kDOI Listing

Controlling protein adsorption modes electrostatically.

Soft Matter 2020 May 27. Epub 2020 May 27.

Department of Material Science and Engineering, Northwestern University, Evanston, Illinois 60208, USA. and Department of Chemistry, Northwestern University, Evanston, USA and Department of Physics and Astronomy, Northwestern University, Evanston, USA.

Protein adsorption on surfaces is ubiquitous in biology and in biotechnology. There are various forces required for controlling protein adsorption. Here, we introduce an explicit ion coarse-grained molecular dynamics simulation approach for studying the effects of electrostatics on protein adsorption, and 2D protein assembly on charged surfaces. Read More

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http://dx.doi.org/10.1039/d0sm00632gDOI Listing

Multi-Site Optical Monitoring of Spinal Cord Ischemia During Spine Distraction.

J Neurotrauma 2020 May 27. Epub 2020 May 27.

Stony Brook University, 12301, Orthopedic Surgery, Stony Brook, New York, United States;

Optimal surgical management of spine trauma will restore blood flow to the ischemic spinal cord. However, spine stabilization may also further exacerbate injury by inducing ischemia. Current electrophysiological technology is not capable of detecting acute changes in spinal cord blood flow or localizing ischemia. Read More

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http://dx.doi.org/10.1089/neu.2020.7012DOI Listing

Recent progress and current opinions in Brillouin microscopy for life science applications.

Biophys Rev 2020 May 26. Epub 2020 May 26.

Fischell Department of Bioengineering, University of Maryland, College Park, MD, USA.

Many important biological functions and processes are reflected in cell and tissue mechanical properties such as elasticity and viscosity. However, current techniques used for measuring these properties have major limitations, such as that they can often not measure inside intact cells and/or require physical contact-which cells can react to and change. Brillouin light scattering offers the ability to measure mechanical properties in a non-contact and label-free manner inside of objects with high spatial resolution using light, and hence has emerged as an attractive method during the past decade. Read More

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http://dx.doi.org/10.1007/s12551-020-00701-9DOI Listing

Application of the Brown dynamics fluctuation-dissipation theorem to the study of Plasmodium berghei transporter protein PbAQP.

Authors:
Liao Y Chen

Front Phys 2020 Apr 17;8. Epub 2020 Apr 17.

Department of Physics and Astronomy, The University of Texas at San Antonio, San Antonio, Texas, USA.

In this article, the Brownian dynamics fluctuation-dissipation theorem (BD-FDT) is applied to the study of transport of neutral solutes across the cellular membrane of Plasmodium berghei (Pb), a disease-causing parasite. Pb infects rodents and causes symptoms in laboratory mice that are comparable to human malaria caused by Plasmodium falciparum (Pf). Due to the relative ease of its genetic engineering, P. Read More

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http://dx.doi.org/10.3389/fphy.2020.00119DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7250396PMC

Cerebral Metabolic Changes During Visuomotor Adaptation Assessed Using Quantitative fMRI.

Front Physiol 2020 8;11:428. Epub 2020 May 8.

Cardiff University Brain Research Imaging Centre (CUBRIC), School of Psychology, Cardiff University, Cardiff, United Kingdom.

The brain retains a lifelong ability to adapt through learning and in response to injury or disease-related damage, a process known as functional neuroplasticity. The neural energetics underlying functional brain plasticity have not been thoroughly investigated experimentally in the healthy human brain. A better understanding of the blood flow and metabolic changes that accompany motor skill acquisition, and which facilitate plasticity, is needed before subsequent translation to treatment interventions for recovery of function in disease. Read More

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http://dx.doi.org/10.3389/fphys.2020.00428DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7227432PMC

Rotational spectroscopy and astronomical search for glutaronitrile.

Astron Astrophys 2020 Apr 10;636. Epub 2020 Apr 10.

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

Context: Nitriles constitute almost 15% of the molecules observed in the interstellar medium (ISM), surprisingly only two dinitriles have been detected in the ISM so far. The lack of astronomical detections for dinitriles may be partly explained by the absence of laboratory rotational spectroscopic data.

Aims: Our goal is to investigate the rotational spectrum of glutaronitrile, N≡C-CH-CH-CH-C≡N, in order to allow its possible detection in the ISM. Read More

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http://dx.doi.org/10.1051/0004-6361/202037769DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7250646PMC

Search and rescue at sea aided by hidden flow structures.

Nat Commun 2020 May 26;11(1):2525. Epub 2020 May 26.

Institute for Mechanical Systems, ETH Zürich, 8092, Zurich, Switzerland.

Every year, hundreds of people die at sea because of vessel and airplane accidents. A key challenge in reducing the number of these fatalities is to make Search and Rescue (SAR) algorithms more efficient. Here, we address this challenge by uncovering hidden TRansient Attracting Profiles (TRAPs) in ocean-surface velocity data. Read More

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http://dx.doi.org/10.1038/s41467-020-16281-xDOI Listing

Cave bacteria-induced amorphous calcium carbonate formation.

Sci Rep 2020 May 26;10(1):8696. Epub 2020 May 26.

Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Magyar tudósok körútja 2, H-1117, Budapest, Hungary.

Amorphous calcium carbonate (ACC) is a precursor of crystalline calcium carbonates that plays a key role in biomineralization and polymorph evolution. Here, we show that several bacterial strains isolated from a Hungarian cave produce ACC and their extracellular polymeric substance (EPS) shields ACC from crystallization. The findings demonstrate that bacteria-produced ACC forms in water-rich environment at room temperature and is stable for at least half year, which is in contrast to laboratory-produced ACC that needs to be stored in a desiccator and kept below 10 °C for avoiding crystallization. Read More

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http://dx.doi.org/10.1038/s41598-020-65667-wDOI Listing

Role of ferroelectric polarization during growth of highly strained ferroelectric materials.

Nat Commun 2020 May 26;11(1):2630. Epub 2020 May 26.

Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY, 11794-3800, USA.

In ferroelectric thin films and superlattices, the polarization is intricately linked to crystal structure. Here we show that it can also play an important role in the growth process, influencing growth rates, relaxation mechanisms, electrical properties and domain structures. This is studied by focusing on the properties of BaTiO thin films grown on very thin layers of PbTiO using x-ray diffraction, piezoforce microscopy, electrical characterization and rapid in-situ x-ray diffraction reciprocal space maps during the growth using synchrotron radiation. Read More

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http://dx.doi.org/10.1038/s41467-020-16356-9DOI Listing

Tuning the interfacial spin-orbit coupling with ferroelectricity.

Nat Commun 2020 May 26;11(1):2627. Epub 2020 May 26.

State Key Laboratory of Surface Physics and Department of Physics, Fudan University, 200433, Shanghai, China.

Detection and manipulation of spin current lie in the core of spintronics. Here we report an active control of a net spin Hall angle, θ(net), in Pt at an interface with a ferroelectric material PZT (PbZrTiO), using its ferroelectric polarization. The spin Hall angle in the ultra-thin Pt layer is measured using the inverse spin Hall effect with a pulsed tunneling current from a ferromagnetic LaSrMnO electrode. Read More

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http://dx.doi.org/10.1038/s41467-020-16401-7DOI Listing

Tuning environmental timescales to evolve and maintain generalists.

Proc Natl Acad Sci U S A 2020 May 26. Epub 2020 May 26.

Department of Physics, The University of Chicago, Chicago, IL 60627;

Natural environments can present diverse challenges, but some genotypes remain fit across many environments. Such "generalists" can be hard to evolve, outcompeted by specialists fitter in any particular environment. Here, inspired by the search for broadly neutralizing antibodies during B cell affinity maturation, we demonstrate that environmental changes on an intermediate timescale can reliably evolve generalists, even when faster or slower environmental changes are unable to do so. Read More

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http://dx.doi.org/10.1073/pnas.1914586117DOI Listing

A Temperature-Controlled Patch Clamp Platform Demonstrated on Jurkat T Lymphocytes and Human Induced Pluripotent Stem Cell-Derived Neurons.

Bioengineering (Basel) 2020 May 22;7(2). Epub 2020 May 22.

Center for Hybrid Nanostructures, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany.

Though patch clamping at room temperature is a widely disseminated standard procedure in the electrophysiological community, it does not represent the biological system in mammals at around 37 °C. In order to better mimic the natural environment in electrophysiological studies, we present a custom-built, temperature-controlled patch clamp platform for upright microscopes, which can easily be adapted to any upright patch clamp setup independently, whether commercially available or home built. Our setup can both cool and heat the platform having only small temperature variations of less than 0. Read More

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http://dx.doi.org/10.3390/bioengineering7020046DOI Listing

The Optoelectronic Properties of p-Type Cr-Deficient Cu[CrMg]O Films Deposited by Reactive Magnetron Sputtering.

Materials (Basel) 2020 May 21;13(10). Epub 2020 May 21.

The Key Lab of Guangdong for Modern Surface Engineering Technology, National Engineering Laboratory for Modern Materials Surface Engineering Technology, Guangdong Institute of New Materials, Guangzhou 510651, China.

CuCrO is one of the most promising p-type transparent conductive oxide (TCO) materials. Its electrical properties can be considerably improved by Mg doping. In this work, Cr-deficient CuCrO thin films were deposited by reactive magnetron sputtering based on 5 at. Read More

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http://dx.doi.org/10.3390/ma13102376DOI Listing

Further evidence that far-UVC for disinfection is unlikely to cause erythema or pre-mutagenic DNA lesions in skin.

Photodermatol Photoimmunol Photomed 2020 May 26. Epub 2020 May 26.

SUPA, School of Physics & Astronomy, University of St Andrews, St Andrews, KY16 9SS, UK.

It is well understood that ultraviolet-C (UVC) radiation is effective for the destruction of micro-organisms and drug-resistant bacteria and is being investigated for its effectiveness at destroying the virus responsible for the current Covid-19 global pandemic. Far-UVC (200 - 220 nm) has been proposed as an effective disinfection radiation that is safe to humans. In 2014, Woods et al. Read More

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http://dx.doi.org/10.1111/phpp.12580DOI Listing

New carbon allotropes derived from nanotubes via a three-fold distortion mechanism.

Phys Chem Chem Phys 2020 May 26. Epub 2020 May 26.

Department of Physics and Astronomy, University of Nevada, Las Vegas, Nevada 89154, USA.

Besides commonly used graphite, carbon nanotubes are also often chosen as precursor materials for the synthesis of new carbon phases. Here we identify, using ab initio calculations, two new three-dimensional crystalline modifications of carbon nanotubes with P63/mcm (D36h) symmetry derived from (6,0) and (9,0) nanotubes via a three-fold distortion assisted reconstruction mechanism. The resulting sp2 + sp3 hybrid network structures have a 24- and 36-atom hexagonal unit cell, termed as (6,0)-hP24 and (9,0)-hP36 carbon, and they topologically correspond to two-dimensional graphyne and graphdiyne. Read More

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http://dx.doi.org/10.1039/d0cp00834fDOI Listing

Cortical cell stiffness is independent of substrate mechanics.

Nat Mater 2020 May 25. Epub 2020 May 25.

Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK.

Cortical stiffness is an important cellular property that changes during migration, adhesion and growth. Previous atomic force microscopy (AFM) indentation measurements of cells cultured on deformable substrates have suggested that cells adapt their stiffness to that of their surroundings. Here we show that the force applied by AFM to a cell results in a significant deformation of the underlying substrate if this substrate is softer than the cell. Read More

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http://dx.doi.org/10.1038/s41563-020-0684-xDOI Listing

Atomic reconstruction in twisted bilayers of transition metal dichalcogenides.

Nat Nanotechnol 2020 May 25. Epub 2020 May 25.

Department of Physics and Astronomy, University of Manchester, Manchester, UK.

Van der Waals heterostructures form a unique class of layered artificial solids in which physical properties can be manipulated through controlled composition, order and relative rotation of adjacent atomic planes. Here we use atomic-resolution transmission electron microscopy to reveal the lattice reconstruction in twisted bilayers of the transition metal dichalcogenides, MoS and WS. For twisted 3R bilayers, a tessellated pattern of mirror-reflected triangular 3R domains emerges, separated by a network of partial dislocations for twist angles θ < 2°. Read More

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http://dx.doi.org/10.1038/s41565-020-0682-9DOI Listing

DECAES - DEcomposition and Component Analysis of Exponential Signals.

Z Med Phys 2020 May 22. Epub 2020 May 22.

Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, V6T 1Z1 Vancouver, BC, Canada; UBC MRI Research Centre, 2221 Wesbrook Mall, V6T 2B5 Vancouver, BC, Canada; Department of Radiology, University of British Columbia, 2775 Laurel Street, V5Z 1M9 Vancouver, BC, Canada; Department of Pediatrics, Faculty of Medicine, University of British Columbia, 4480 Oak Street, BC Children's Hospital, V6H 3V4 Vancouver, BC, Canada.

Combinations of multiple exponentially decaying signals are found across many disciplines of science. Decomposition of these multi-exponential signals into their individual components provides insight into the various contributors to the signal. Magnetic resonance images, for instance, can be acquired with multiple gradient or spin echoes to provide voxel by voxel multi-exponential T2* or T2 decays, respectively. Read More

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http://dx.doi.org/10.1016/j.zemedi.2020.04.001DOI Listing

The effects of melatonin, serotonin, tryptophan and NAS on the biophysical properties of DPPC monolayers.

Biochim Biophys Acta Biomembr 2020 May 22:183363. Epub 2020 May 22.

Department of Physics and Astronomy, University of Waterloo, Waterloo, Canada; Department of Biology, University of Waterloo, Waterloo, Canada; Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, Canada. Electronic address:

Melatonin is a neurohormone that has been shown to be protective in Alzheimer's diseases against amyloid-β (Aβ) toxicity, which involves interaction of Aβ with neuronal membrane. Non-specific interactions of melatonin with cell membrane may play a physiological role in this process by preserving membrane fluidity. In the brain, melatonin is derived from the amino acid tryptophan through a pathway that includes serotonin and N-acetylserotonin (NAS). Read More

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http://dx.doi.org/10.1016/j.bbamem.2020.183363DOI Listing

Localized Surface Plasmon Resonance Enhanced Light Absorption in AuCu/CsPbCl Core/Shell Nanocrystals.

Adv Mater 2020 May 25:e2002163. Epub 2020 May 25.

Department of Physics and Astronomy, University of Kansas, Lawrence, KS, 66045, USA.

Localized surface plasmon resonance (LSPR) is shown to be effective in trapping light for enhanced light absorption and hence performance in photonic and optoelectronic devices. Implementation of LSPR in all-inorganic perovskite nanocrystals (PNCs) is particularly important considering their unique advantages in optoelectronics. Motivated by this, the first success in colloidal synthesis of AuCu/CsPbCl core/shell PNCs and observation of enhanced light absorption by the perovskite CsPbCl shell of thickness in the range of 2-4 nm, enabled by the LSPR AuCu core of an average diameter of 7. Read More

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http://dx.doi.org/10.1002/adma.202002163DOI Listing

An audit of uncertainty in multi-scale cardiac electrophysiology models.

Philos Trans A Math Phys Eng Sci 2020 Jun 25;378(2173):20190335. Epub 2020 May 25.

Universitade Federal de Juiz de Fora, Juiz de Fora, Brazil.

Models of electrical activation and recovery in cardiac cells and tissue have become valuable research tools, and are beginning to be used in safety-critical applications including guidance for clinical procedures and for drug safety assessment. As a consequence, there is an urgent need for a more detailed and quantitative understanding of the ways that uncertainty and variability influence model predictions. In this paper, we review the sources of uncertainty in these models at different spatial scales, discuss how uncertainties are communicated across scales, and begin to assess their relative importance. Read More

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http://dx.doi.org/10.1098/rsta.2019.0335DOI Listing

Considering discrepancy when calibrating a mechanistic electrophysiology model.

Philos Trans A Math Phys Eng Sci 2020 Jun 25;378(2173):20190349. Epub 2020 May 25.

School of Mathematics and Statistics, University of Sheffield, Sheffield, UK.

Uncertainty quantification (UQ) is a vital step in using mathematical models and simulations to take decisions. The field of cardiac simulation has begun to explore and adopt UQ methods to characterize uncertainty in model inputs and how that propagates through to outputs or predictions; examples of this can be seen in the papers of this issue. In this review and perspective piece, we draw attention to an important and under-addressed source of uncertainty in our predictions-that of uncertainty in the model structure or the equations themselves. Read More

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http://dx.doi.org/10.1098/rsta.2019.0349DOI Listing

Urban air quality, climate, and pollution: from measurement to modeling applications.

Environ Sci Pollut Res Int 2020 May 23. Epub 2020 May 23.

Department of Atmospheric Sciences, Institute of Astronomy, Geophysics and Atmospheric Sciences, Universidade de São Paulo, São Paulo, Brazil.

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http://dx.doi.org/10.1007/s11356-020-09336-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7245185PMC

Reversible inhibition and reactivation of electron transfer in photosystem I.

Photosynth Res 2020 May 23. Epub 2020 May 23.

Department of Physics and Astronomy, Georgia State University, Atlanta, GA, 30303, USA.

In photosystem I (PSI) complexes at room temperature electron transfer from A to F is an order of magnitude faster on the B-branch compared to the A-branch. One factor that might contribute to this branch asymmetry in time constants is TrpB673 (Thermosynechococcus elongatus numbering), which is located between A and F. The corresponding residue on the A-branch, between A and F, is GlyA693. Read More

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http://dx.doi.org/10.1007/s11120-020-00760-9DOI Listing

On the possibility of direct triplet state excitation of indole.

J Photochem Photobiol B 2020 May 16;208:111897. Epub 2020 May 16.

Department of Microbiology, Immunology, and Genetics, Center for Fluorescence Technologies and Nanomedicine, University of North Texas Health Science Center, Fort Worth, TX 76107, USA.

We studied the luminescence properties of indole in poly (vinyl alcohol) (PVA) film. The indole molecules are effectively immobilized in this polymer film and display both fluorescence and phosphorescence emission at room temperature. We noticed that the phosphorescence of indole in PVA film can be effectively excited at a longer wavelength than its typical singlet to triplet population route involving intersystem crossing. Read More

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http://dx.doi.org/10.1016/j.jphotobiol.2020.111897DOI Listing

Channel and cut-bluff failure connectivity in a river system: Case study of the braided-wandering Belá River, Western Carpathians, Slovakia.

Sci Total Environ 2020 May 14;733:139409. Epub 2020 May 14.

Institute of Geography, Faculty of Science, UPJŠ in Košice, Jesenná 5, 040 01 Košice, Slovakia.

Straightforward sediment transport is not common in nature and material is storage during transport and reworked by the same processed that lead to initial mass erosion. Despite the development of quantitative assessment by application high accuracy topography measurement, lack of conceptualisation and combination with precise elevation model changes is still missing. This paper presents a field-based channel-bluff connectivity study based on a sediment cascade approach. Read More

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http://dx.doi.org/10.1016/j.scitotenv.2020.139409DOI Listing

Synthesis of studies on significant atmospheric electrical effects of major nuclear accidents in Chernobyl and Fukushima.

Sci Total Environ 2020 May 8;733:139271. Epub 2020 May 8.

Research Centre for Astronomy and Earth Sciences, GGI, Hungarian Academy of Sciences, Sopron, Hungary.

Radioactive materials released during the two most serious nuclear accidents in history, at Chernobyl and Fukushima, caused exceptionally significant contamination and perturbations of the environment. Among them, this paper focuses on the effects related to the atmospheric electricity (AE). Measurements of the most significant disturbances in the values of various AE parameters recorded near ground level are reviewed and the corresponding results are jointly evaluated. Read More

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http://dx.doi.org/10.1016/j.scitotenv.2020.139271DOI Listing

Linked patterns of biological and environmental covariation with brain structure in adolescence: a population-based longitudinal study.

Mol Psychiatry 2020 May 22. Epub 2020 May 22.

Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, USA.

Adolescence is a period of major brain reorganization shaped by biologically timed and by environmental factors. We sought to discover linked patterns of covariation between brain structural development and a wide array of these factors by leveraging data from the IMAGEN study, a longitudinal population-based cohort of adolescents. Brain structural measures and a comprehensive array of non-imaging features (relating to demographic, anthropometric, and psychosocial characteristics) were available on 1476 IMAGEN participants aged 14 years and from a subsample reassessed at age 19 years (n = 714). Read More

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http://dx.doi.org/10.1038/s41380-020-0757-xDOI Listing

Temporal sequences of brain activity at rest are constrained by white matter structure and modulated by cognitive demands.

Commun Biol 2020 May 22;3(1):261. Epub 2020 May 22.

Department of Bioengineering, School of Engineering & Applied Science, Philadelphia, PA, 19104, USA.

A diverse set of white matter connections supports seamless transitions between cognitive states. However, it remains unclear how these connections guide the temporal progression of large-scale brain activity patterns in different cognitive states. Here, we analyze the brain's trajectories across a set of single time point activity patterns from functional magnetic resonance imaging data acquired during the resting state and an n-back working memory task. Read More

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http://dx.doi.org/10.1038/s42003-020-0961-xDOI Listing

Colossal flexoresistance in dielectrics.

Nat Commun 2020 May 22;11(1):2586. Epub 2020 May 22.

Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Korea.

Dielectrics have long been considered as unsuitable for pure electrical switches; under weak electric fields, they show extremely low conductivity, whereas under strong fields, they suffer from irreversible damage. Here, we show that flexoelectricity enables damage-free exposure of dielectrics to strong electric fields, leading to reversible switching between electrical states-insulating and conducting. Applying strain gradients with an atomic force microscope tip polarizes an ultrathin film of an archetypal dielectric SrTiO via flexoelectricity, which in turn generates non-destructive, strong electrostatic fields. Read More

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http://dx.doi.org/10.1038/s41467-020-16207-7DOI Listing

Kinesin-14 motors drive a right-handed helical motion of antiparallel microtubules around each other.

Nat Commun 2020 May 22;11(1):2565. Epub 2020 May 22.

B CUBE-Center for Molecular Bioengineering, Technische Universität Dresden, 01307, Dresden, Germany.

Within the mitotic spindle, kinesin motors cross-link and slide overlapping microtubules. Some of these motors exhibit off-axis power strokes, but their impact on motility and force generation in microtubule overlaps has not been investigated. Here, we develop and utilize a three-dimensional in vitro motility assay to explore kinesin-14, Ncd, driven sliding of cross-linked microtubules. Read More

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http://dx.doi.org/10.1038/s41467-020-16328-zDOI Listing

Magnetotransport studies of Fe vacancy-ordered FeSe nanowires.

Proc Natl Acad Sci U S A 2020 May 22. Epub 2020 May 22.

Institute of Physics, Academia Sinica, 115 Taipei, Taiwan;

We studied the electrical transport of FeSe single-crystal nanowires exhibiting √5 × √5 Fe-vacancy order and mixed valence of Fe. FeSe compound has been identified as the parent phase of FeSe superconductor. A first-order metal-insulator (MI) transition of transition temperature ∼ 28 K is observed at zero magnetic fields (). Read More

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http://dx.doi.org/10.1073/pnas.2000833117DOI Listing

IDyOT architecture - is this how minds operate?

Phys Life Rev 2020 May 19. Epub 2020 May 19.

Department of Informatics, Faculty of Physics, Astronomy and Informatics, and Neurocognitive Laboratory, Center for Modern Interdisciplinary Technologies, Nicolaus Copernicus University, Toruń, Poland. Electronic address:

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http://dx.doi.org/10.1016/j.plrev.2020.04.001DOI Listing

Route to Intelligent Imaging Reconstruction via Terahertz Nonlinear Ghost Imaging.

Micromachines (Basel) 2020 May 20;11(5). Epub 2020 May 20.

Emergent Photonics (EPic) Laboratory, Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH, UK.

Terahertz (THz) imaging is a rapidly emerging field, thanks to many potential applications in diagnostics, manufacturing, medicine and material characterisation. However, the relatively coarse resolution stemming from the large wavelength limits the deployment of THz imaging in micro- and nano-technologies, keeping its potential benefits out-of-reach in many practical scenarios and devices. In this context, single-pixel techniques are a promising alternative to imaging arrays, in particular when targeting subwavelength resolutions. Read More

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http://dx.doi.org/10.3390/mi11050521DOI Listing

Conformation, flexibility and hydration of hyaluronic acid by molecular dynamics simulations.

Carbohydr Res 2020 May 11;493:108026. Epub 2020 May 11.

Center of Excellence in Computational Chemistry, Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok, 10330, Thailand. Electronic address:

Hyaluronic acid (HA) is a biopolymer of disaccharide with two alternate glycosidic bonds, β(1,3) and β(1,4). A molecular dynamics study presented here unveiled conformational variability in association with the flexibility of the glycosidic linkers, which depends on the number of disaccharide units. HA chain maintains a rigid rod-like conformation with short chain lengths. Read More

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http://dx.doi.org/10.1016/j.carres.2020.108026DOI Listing

Evaluation of proton beam radiation-induced skin injury in a murine model using a clinical SOBP.

PLoS One 2020 22;15(5):e0233258. Epub 2020 May 22.

Institute of Molecular Bioimaging and Physiology (IBFM-CNR), Cefalù (PA), Italy.

The purpose of this paper is to characterize the skin deterministic damage due to the effect of proton beam irradiation in mice occurred during a long-term observational experiment. This study was initially defined to evaluate the insurgence of myelopathy irradiating spinal cords with the distal part of a Spread-out Bragg peak (SOBP). To the best of our knowledge, no study has been conducted highlighting high grades of skin injury at the dose used in this paper. Read More

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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0233258PLOS

Direct Observation of Flatband Loop States Arising from Nontrivial Real-Space Topology.

Phys Rev Lett 2020 May;124(18):183901

The MOE Key Laboratory of Weak-Light Nonlinear Photonics, TEDA Applied Physics Institute and School of Physics, Nankai University, Tianjin 300457, China.

Topological properties of lattices are typically revealed in momentum space using concepts such as the Chern number. Here, we study unconventional loop states, namely, the noncontractible loop states (NLSs) and robust boundary modes, mediated by nontrivial topology in real space. While such states play a key role in understanding fundamental physics of flatband systems, their experimental observation has been hampered because of the challenge in realizing desired boundary conditions. Read More

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http://dx.doi.org/10.1103/PhysRevLett.124.183901DOI Listing

Search for Dark Matter Induced Deexcitation of ^{180}Ta^{m}.

Phys Rev Lett 2020 May;124(18):181802

Institut für Kern- und Teilchenphysik, Technische Universität Dresden, Zellescher Weg 19, 01069 Dresden Germany.

Weak-scale dark matter particles, in collisions with nuclei, can mediate transitions between different nuclear energy levels. In particular, owing to sizeable momentum exchange, dark matter particles can enable de-excitation of nuclear isomers that are extremely long lived with respect to regular radioactive decays. In this Letter, we utilize data from a past experiment with ^{180}Ta^{m} to search for γ lines that would accompany dark matter induced de-excitation of this isomer. Read More

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http://dx.doi.org/10.1103/PhysRevLett.124.181802DOI Listing

Voltage-Controlled Antiferromagnetism in Magnetic Tunnel Junctions.

Phys Rev Lett 2020 May;124(18):187701

Department of Physics, University of Arizona, Tucson, Arizona 85721, USA.

We demonstrate a voltage-controlled exchange bias effect in CoFeB/MgO/CoFeB magnetic tunnel junctions that is related to the interfacial Fe(Co)O_{x} formed between the CoFeB electrodes and the MgO barrier. The unique combination of interfacial antiferromagnetism, giant tunneling magnetoresistance, and sharp switching of the perpendicularly magnetized CoFeB allows sensitive detection of the exchange bias. We find that the exchange bias field can be isothermally controlled by magnetic fields at low temperatures. Read More

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http://dx.doi.org/10.1103/PhysRevLett.124.187701DOI Listing

Fluorescence Time Delay in Multistep Auger Decay as an Internal Clock.

Phys Rev Lett 2020 May;124(18):183001

Department of Materials and Life Sciences, Sophia University, Tokyo 102-8554, Japan.

Differences in postcollision interaction (PCI) effects on Kr L_{3}M_{4,5}M_{4,5} Auger electron spectra were observed, depending on whether the initial photoionization occurred slightly above the K threshold or slightly above the L_{3} threshold. For the former, KL fluorescence emission most likely happens and then Auger processes due to the L_{3} hole follow. The time delay due to fluorescence causes a reduced shift of the Auger peak and tailing toward lower energy, since the Auger overtaking of the photoelectron happens later in time and at a location farther away from the ionic core, compared to the case for the simple one-step L_{3}M_{4,5}M_{4,5} Auger decay after L-shell photoionization. Read More

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http://dx.doi.org/10.1103/PhysRevLett.124.183001DOI Listing

Operator Lévy Flight: Light Cones in Chaotic Long-Range Interacting Systems.

Phys Rev Lett 2020 May;124(18):180601

Condensed Matter Theory Center, Maryland Center for Fundamental Physics, Joint Center for Quantum Information and Computer Science, and Department of Physics, University of Maryland, College Park, Maryland 20742, USA.

We argue that chaotic power-law interacting systems have emergent limits on information propagation, analogous to relativistic light cones, which depend on the spatial dimension d and the exponent α governing the decay of interactions. Using the dephasing nature of quantum chaos, we map the problem to a stochastic model with a known phase diagram. A linear light cone results for α≥d+1/2. Read More

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http://dx.doi.org/10.1103/PhysRevLett.124.180601DOI Listing

Reactive Momentum Transfer Contributes to the Self-Propulsion of Janus Particles.

Phys Rev Lett 2020 May;124(18):188001

Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom.

We report simulations of a spherical Janus particle undergoing exothermic surface reactions around one pole only. Our model excludes self-phoretic transport by design. Nevertheless, net motion occurs from direct momentum transfer between solvent and colloid, with speed scaling as the square root of the energy released during the reaction. Read More

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http://dx.doi.org/10.1103/PhysRevLett.124.188001DOI Listing

Symmetrization of Thin Freestanding Liquid Films via a Capillary-Driven Flow.

Phys Rev Lett 2020 May;124(18):184502

UMR CNRS Gulliver 7083, ESPCI Paris, PSL Research University, 75005 Paris, France.

We present experiments to study the relaxation of a nanoscale cylindrical perturbation at one of the two interfaces of a thin viscous freestanding polymeric film. Driven by capillarity, the film flows and evolves toward equilibrium by first symmetrizing the perturbation between the two interfaces and eventually broadening the perturbation. A full-Stokes hydrodynamic model is presented, which accounts for both the vertical and lateral flows and which highlights the symmetry in the system. Read More

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http://dx.doi.org/10.1103/PhysRevLett.124.184502DOI Listing

High-Temperature Charge-Stripe Correlations in La_{1.675}Eu_{0.2}Sr_{0.125}CuO_{4}.

Phys Rev Lett 2020 May;124(18):187002

Physik-Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland.

We use resonant inelastic x-ray scattering to investigate charge-stripe correlations in La_{1.675}Eu_{0.2}Sr_{0. Read More

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http://dx.doi.org/10.1103/PhysRevLett.124.187002DOI Listing

Darcy's Law without Friction in Active Nematic Rheology.

Phys Rev Lett 2020 May;124(18):187801

SUPA, School of Physics and Astronomy, University of Edinburgh, Peter Guthrie Tait Road, Edinburgh EH9 3FD, United Kingdom.

We study the dynamics of a contractile active nematic fluid subjected to a Poiseuille flow. In a quasi-1D geometry, we find that the linear rheology of this material is reminiscent of Darcy's law in complex fluids, with a pluglike flow decaying to zero over a well-defined "permeation" length. As a result, the viscosity increases with size, but never diverges, thereby evading the yield stress predicted by previous theories. Read More

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http://dx.doi.org/10.1103/PhysRevLett.124.187801DOI Listing

On the Nature of Explanations Offered by Network Science: A Perspective From and for Practicing Neuroscientists.

Top Cogn Sci 2020 May 22. Epub 2020 May 22.

Department of Bioengineering, School of Engineering & Applied Science, University of Pennsylvania.

Network neuroscience represents the brain as a collection of regions and inter-regional connections. Given its ability to formalize systems-level models, network neuroscience has generated unique explanations of neural function and behavior. The mechanistic status of these explanations and how they can contribute to and fit within the field of neuroscience as a whole has received careful treatment from philosophers. Read More

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http://dx.doi.org/10.1111/tops.12504DOI Listing

Cosmic tau neutrino detection via Cherenkov signals from air showers from Earth-emerging taus.

Phys Rev D 2019 Sep 18;100(6). Epub 2019 Sep 18.

NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA.

We perform a new, detailed calculation of the flux and energy spectrum of Earth-emerging leptons generated from the interactions of tau neutrinos and antineutrinos in the Earth. A layered model of the Earth is used to describe the variable density profile of the Earth. Different assumptions regarding the neutrino charged- and neutral-current cross sections as well as the -lepton energy loss models are used to quantify their contributions to the systematic uncertainty. Read More

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http://dx.doi.org/10.1103/physrevd.100.063010DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7241579PMC
September 2019