41,408 results match your criteria Astronomy & Astrophysics[Journal]

Dynamic confocal Raman spectroscopy of flowing blood in bionic blood vessel.

Spectrochim Acta A Mol Biomol Spectrosc 2021 Apr 29;259:119890. Epub 2021 Apr 29.

Shandong Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, School of Space Science and Physics, Institute of Space Sciences, Shandong University, Weihai, Shandong 264209, China.

How to quickly and safely identify blood species has always been an urgent problem for scientists. Smear test method has the risk of blood contamination, and the blood itself may carry some unknown viruses or pathogens, which will bring health risks to the testing personnel. Therefore, in order to meet the urgent needs of rapid and safe detection of blood, a technology which can detect dynamic confocal Raman spectroscopy of flowing blood in bionic blood vessel was proposed. Read More

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Towards rapid intraoperative axial localization of spinal cord ischemia with epidural diffuse correlation monitoring.

PLoS One 2021 10;16(5):e0251271. Epub 2021 May 10.

Department of Anesthesiology and Pain Management, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America.

Spinal cord ischemia leads to iatrogenic injury in multiple surgical fields, and the ability to immediately identify onset and anatomic origin of ischemia is critical to its management. Current clinical monitoring, however, does not directly measure spinal cord blood flow, resulting in poor sensitivity/specificity, delayed alerts, and delayed intervention. We have developed an epidural device employing diffuse correlation spectroscopy (DCS) to monitor spinal cord ischemia continuously at multiple positions. Read More

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Zinc stable isotope analysis reveals Zn dyshomeostasis in benign tumours, breast cancer, and adjacent histologically normal tissue.

Metallomics 2021 May 10. Epub 2021 May 10.

Department of Earth Science & Engineering, Imperial College London, Exhibition Road, London, SW7 2AZ, UK.

The disruption of Zn homeostasis has been linked with breast cancer development and progression. To enhance our understanding of changes in Zn homeostasis both inside and around the tumour microenvironment, Zn concentrations and isotopic compositions (δ66Zn) were determined in benign (BT) and malignant (MT) tumours, healthy tissue from reduction mammoplasty (HT), and histologically normal tissue adjacent to benign (NAT(BT)) and malignant tumours (NAT(MT)). Mean Zn concentrations in NAT(BT) are 5. Read More

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Venus, an Astrobiology Target.

Astrobiology 2021 May 7. Epub 2021 May 7.

NASA Goddard Institute for Space Studies, New York, New York, USA.

We present a case for the exploration of Venus as an astrobiology target-(1) investigations focused on the likelihood that liquid water existed on the surface in the past, leading to the potential for the origin and evolution of life, (2) investigations into the potential for habitable zones within Venus' present-day clouds and Venus-like exo atmospheres, (3) theoretical investigations into how active aerobiology may impact the radiative energy balance of Venus' clouds and Venus-like atmospheres, and (4) application of these investigative approaches toward better understanding the atmospheric dynamics and habitability of exoplanets. The proximity of Venus to Earth, guidance for exoplanet habitability investigations, and access to the potential cloud habitable layer and surface for prolonged extended measurements together make the planet a very attractive target for near term astrobiological exploration. Read More

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A Fluorescence Sensor for Pb Detection Based on Liquid Crystals and Aggregation-Induced Emission Luminogens.

ACS Appl Mater Interfaces 2021 May 9. Epub 2021 May 9.

Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen 518055, China.

Heavy metals, such as lead ions, are regarded as the main environmental contaminants and have a negative impact on human bodies, making detection technologies of lead ions critical. However, most existing detection methods suffer from time consumption, complicated sample pretreatment, and expensive equipment, which hinder their broad use in real-time detection. Herein, we show a new fluorescence sensor for detecting lead ions derived from liquid crystals doped with an aggregation-induced emission luminogen. Read More

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LABEC, the INFN ion beam laboratory of nuclear techniques for environment and cultural heritage.

Eur Phys J Plus 2021 30;136(4):472. Epub 2021 Apr 30.

INFN Division of Florence and Department of Physics and Astronomy, University of Florence, via G. Sansone 1, 50019 Sesto Fiorentino, Italy.

The LABEC laboratory, the INFN ion beam laboratory of nuclear techniques for environment and cultural heritage, located in the Scientific and Technological Campus of the University of Florence in Sesto Fiorentino, started its operational activities in 2004, after INFN decided in 2001 to provide our applied nuclear physics group with a large laboratory dedicated to applications of accelerator-related analytical techniques, based on a new 3 MV Tandetron accelerator. The new accelerator greatly improved the performance of existing Ion Beam Analysis (IBA) applications (for which we were using since the 1980s an old single-ended Van de Graaff accelerator) and in addition allowed to start a novel activity of Accelerator Mass Spectrometry (AMS), in particular for C dating. Switching between IBA and AMS operation became very easy and fast, which allowed us high flexibility in programming the activities, mainly focused on studies of cultural heritage and atmospheric aerosol composition, but including also applications to biology, geology, material science and forensics, ion implantation, tests of radiation damage to components, detector performance tests and low-energy nuclear physics. Read More

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(Mis)Understanding scientific disagreement: Success versus pursuit-worthiness in theory choice.

Stud Hist Philos Sci 2021 Feb 1;85:166-175. Epub 2020 Nov 1.

University of Michigan, Ann Arbor, MI, United States. Electronic address:

Scientists often diverge widely when choosing between research programs. This can seem to be rooted in disagreements about which of several theories, competing to address shared questions or phenomena, is currently the most epistemically or explanatorily valuable-i.e. Read More

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February 2021

Preclinical dosimetric studies of Lu-scFvD2B and comparison with Lu-PSMA-617 and Lu-iPSMA endoradiotherapeutic agents.

Med Phys 2021 May 9. Epub 2021 May 9.

Department of Physics and Astronomy, University of Padua, Via Marzolo 8, 35131, Padua, Italy.

Purpose: Internal dosimetry has become a very important tool to evaluate the risks and benefits of new endoradiotherapeutic agents. Nowadays, some of the most successful targeted radionuclide therapy (TRT) agents are Lu-DOTA conjugates based on low molecular weight (LMW) Glu-ureido PSMA inhibitors. It has however been demonstrated that the DOTA chelating moiety reduces the internalization of the LMW-PSMA agent and its radiation dose to the tumour. Read More

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SARS-CoV-2, Hemoglobin and Protoporphyrin IX: Interactions and Perspectives.

Photodiagnosis Photodyn Ther 2021 May 6:102324. Epub 2021 May 6.

king Saud University, Physics and Astronomy Department, Laser Group, College of Science, Riyadh, Saudi Arabia.

Background: SARS-CoV-2 attacks hemoglobin through its structural protein ORF3a dissociating the iron from the heme since iron is necessary by the cell machinery for the virus replication. In this process protoporphyrin (PpIX) is released.

Methods: The decrease in the hemoglobin levels observed in patients with Covid-19 is frequently accompanied by an increase in PpIX levels. Read More

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Fabrication of Nd and Yb doped NIR emitting nano fluorescent probe: A candidate for bioimaging applications.

Mater Sci Eng C Mater Biol Appl 2021 Jun 1;125:112095. Epub 2021 Apr 1.

Department of Physics, Periyar University, Salem 636 011, Tamil Nadu, India. Electronic address:

The intentional design of rare earth doped luminescent architecture exhibits unique optical properties and it can be considered as a promising and potential probe for optical imaging applications. Calcium fluoride (CaF) nanoparticles doped with optimum concentration of Nd and Yb as sensitizer and activator, respectively, were synthesized by wet precipitation method and characterized by x-ray diffraction (XRD) and photoluminescence. In spite of the fact that the energy transfer takes place from Nd to Yb, the luminescence intensity was found to be weak due to the lattice defects generated from the doping of trivalent cations (Nd and Yb) for divalent host cations (Ca). Read More

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The role of syncytia during viral infections.

J Theor Biol 2021 May 5:110749. Epub 2021 May 5.

Department of Physics and Astronomy, Texas Christian University, Fort Worth, TX. Electronic address:

Respiratory syncytial virus (RSV) is a common, contagious infection of the lungs and the respiratory tract. RSV is characterized by syncytia, which are multinuclear cells created by cells that have fused together. We use a mathematical model to study how different assumptions about the viral production and lifespan of syncytia change the resulting infection time course. Read More

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Unravelling the mechanisms of Type 1A topoisomerases using single-molecule approaches.

Nucleic Acids Res 2021 May 8. Epub 2021 May 8.

Institute of Structural and Molecular Biology, University College London, Gower Street, London WC1E 6BT, UK.

Topoisomerases are essential enzymes that regulate DNA topology. Type 1A family topoisomerases are found in nearly all living organisms and are unique in that they require single-stranded (ss)DNA for activity. These enzymes are vital for maintaining supercoiling homeostasis and resolving DNA entanglements generated during DNA replication and repair. Read More

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A structural intermediate pre-organizes the add adenine riboswitch for ligand recognition.

Nucleic Acids Res 2021 May 8. Epub 2021 May 8.

Department of Biology, Faculty of Science, Université de Sherbrooke, Sherbrooke, Quebec J1K 2R1, Canada.

Riboswitches are RNA sequences that regulate gene expression by undergoing structural changes upon the specific binding of cellular metabolites. Crystal structures of purine-sensing riboswitches have revealed an intricate network of interactions surrounding the ligand in the bound complex. The mechanistic details about how the aptamer folding pathway is involved in the formation of the metabolite binding site have been previously shown to be highly important for the riboswitch regulatory activity. Read More

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Fluorescence and thermal imaging of non-melanoma skin cancers before and during photodynamic therapy.

Photodiagnosis Photodyn Ther 2021 May 4:102327. Epub 2021 May 4.

Photobiology Unit, NHS Tayside, Ninewells Hospital and Medical School, Dundee, UK; The Scottish Photodynamic Therapy Centre, Dundee, UK; School of Medicine, University of Dundee, Dundee, UK.

Background: Photodynamic therapy (PDT) has been shown to be less effective on the extremities. Protoporphyrin-IX (PpIX) fluorescence and skin surface temperature are variables that have been implicated in the differences in efficacy with body site, but objective studies have not been undertaken.

Objectives: To further investigate observations from our previous study that temperature and fluorescence during pro-drug incubation are correlated, through a prospective objective investigation of the relationships between fluorescence and skin surface temperature before and during PDT and relationships with body site and efficacy. Read More

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A biochemical mechanism for time-encoding memory formation within individual synapses of Purkinje cells.

PLoS One 2021 7;16(5):e0251172. Epub 2021 May 7.

Complexity Science Group, Department of Physics and Astronomy, University of Calgary, Calgary, Alberta, Canada.

Within the classical eye-blink conditioning, Purkinje cells within the cerebellum are known to suppress their tonic firing rates for a well defined time period in response to the conditional stimulus after training. The temporal profile of the drop in tonic firing rate, i.e. Read More

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Elliptic Flow of Electrons from Beauty-Hadron Decays in Pb-Pb Collisions at sqrt[s_{NN}]=5.02  TeV.

Phys Rev Lett 2021 Apr;126(16):162001

Central China Normal University, Wuhan, China.

The elliptic flow of electrons from beauty hadron decays at midrapidity (|y|<0.8) is measured in Pb-Pb collisions at sqrt[s_{NN}]=5.02  TeV with the ALICE detector at the LHC. Read More

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Test of Lepton-Flavor Universality in B→K^{*}ℓ^{+}ℓ^{-} Decays at Belle.

Phys Rev Lett 2021 Apr;126(16):161801

INFN-Sezione di Napoli, 80126 Napoli.

We present a measurement of R_{K^{*}}, the branching fraction ratio B(B→K^{*}μ^{+}μ^{-})/B(B→K^{*}e^{+}e^{-}), for both charged and neutral B mesons. The ratio for the charged case R_{K^{*+}} is the first measurement ever performed. In addition, we report absolute branching fractions for the individual modes in bins of the squared dilepton invariant mass q^{2}. Read More

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Non-Hermiticity-Governed Active Photonic Resonances.

Phys Rev Lett 2021 Apr;126(16):163901

Department of Physics and Astronomy, College of Staten Island, CUNY, Staten Island, New York 10314, USA.

Photonic resonances play an essential role in the generation and propagation of light in optical and photonic devices, as well as in light-matter interaction, including nonlinear optical responses. Previous studies in lasers and other open systems have shown exotic roles played by non-Hermiticity on modifying passive resonances, defined in the absence of optical gain and loss. Here we report a new type of resonances in non-Hermitian photonic systems that does not originate from a passive resonance, identified by analyzing a unique quantization condition in the non-Hermitian extension of the Wentzel-Kramers-Brillouin method. Read More

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Synchronizing Chaos with Imperfections.

Phys Rev Lett 2021 Apr;126(16):164101

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

Previous research on nonlinear oscillator networks has shown that chaos synchronization is attainable for identical oscillators but deteriorates in the presence of parameter mismatches. Here, we identify regimes for which the opposite occurs and show that oscillator heterogeneity can synchronize chaos for conditions under which identical oscillators cannot. This effect is not limited to small mismatches and is observed for random oscillator heterogeneity on both homogeneous and heterogeneous network structures. Read More

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Solutions of Modular Bootstrap Constraints from Quantum Codes.

Phys Rev Lett 2021 Apr;126(16):161602

Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506, USA.

Modular invariance imposes rigid constraints on the partition functions of two-dimensional conformal field theories (CFTs). Many fundamental results follow strictly from modular invariance and unitarity, giving rise to the numerical modular bootstrap program. Here we report on a way to relate a particular family of quantum error correcting codes to a family of "code CFTs," which forms a subset of the space of Narain CFTs. Read More

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Novel Representation of an Integrated Correlator in N=4 Supersymmetric Yang-Mills Theory.

Phys Rev Lett 2021 Apr;126(16):161601

School of Physics and Astronomy, Queen Mary University of London, London E1 4NS, United Kingdom.

An integrated correlator of four superconformal stress-tensor primaries of N=4 supersymmetric SU(N) Yang-Mills theory (SYM), originally obtained by localization, is reexpressed as a two-dimensional lattice sum that is manifestly invariant under SL(2,Z) S duality. This expression is shown to satisfy a novel Laplace equation in the complex coupling constant τ that relates the SU(N) integrated correlator to those of the SU(N+1) and SU(N-1) theories. The lattice sum is shown to precisely reproduce known perturbative and nonperturbative properties of N=4 SYM for any finite N, as well as extending previously conjectured properties of the large-N expansion. Read More

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Exciton-Exciton Interaction beyond the Hydrogenic Picture in a MoSe_{2} Monolayer in the Strong Light-Matter Coupling Regime.

Phys Rev Lett 2021 Apr;126(16):167401

Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, 38000 Grenoble, France.

In transition metal dichalcogenides' layers of atomic-scale thickness, the electron-hole Coulomb interaction potential is strongly influenced by the sharp discontinuity of the dielectric function across the layer plane. This feature results in peculiar nonhydrogenic excitonic states in which exciton-mediated optical nonlinearities are predicted to be enhanced compared to their hydrogenic counterparts. To demonstrate this enhancement, we perform optical transmission spectroscopy of a MoSe_{2} monolayer placed in the strong coupling regime with the mode of an optical microcavity and analyze the results quantitatively with a nonlinear input-output theory. Read More

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Angular Analysis of the B^{+}→K^{*+}μ^{+}μ^{-} Decay.

Phys Rev Lett 2021 Apr;126(16):161802

Laboratoire Leprince-ringuet (llr), Palaiseau, France.

We present an angular analysis of the B^{+}→K^{*+}(→K_{S}^{0}π^{+})μ^{+}μ^{-} decay using 9  fb^{-1} of pp collision data collected with the LHCb experiment. For the first time, the full set of CP-averaged angular observables is measured in intervals of the dimuon invariant mass squared. Local deviations from standard model predictions are observed, similar to those in previous LHCb analyses of the isospin-partner B^{0}→K^{*0}μ^{+}μ^{-} decay. Read More

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Selective Enhancement of Spectroscopic Features by Quantum Optimal Control.

Phys Rev Lett 2021 Apr;126(16):163202

Departments of Chemistry and Physics and Astronomy, University of California, Irvine, California 92697-2025, USA.

Tailored light can be used to steer atomic motions into selected quantum pathways. In optimal control theory (OCT), the target is usually expressed in terms of the molecular wave function, a quantity that is not directly observable in experiment. We present simulations using OCT that optimize the spectroscopic signal itself. Read More

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Topological Two-Dimensional Floquet Lattice on a Single Superconducting Qubit.

Phys Rev Lett 2021 Apr;126(16):163602

Department of Physics, TFK, Technische Universität München, James-Franck-Straße 1, D-85748 Garching, Germany.

Current noisy intermediate-scale quantum (NISQ) devices constitute powerful platforms for analog quantum simulation. The exquisite level of control offered by state-of-the-art quantum computers make them especially promising to implement time-dependent Hamiltonians. We implement quasiperiodic driving of a single qubit in the IBM Quantum Experience and thus experimentally realize a temporal version of the half-Bernevig-Hughes-Zhang Chern insulator. Read More

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Endocannabinoid Gene × Gene Interaction Association to Alcohol Use Disorder in Two Adolescent Cohorts.

Front Psychiatry 2021 20;12:645746. Epub 2021 Apr 20.

Centre Hospitalier Universitaire Sainte-Justine Research Center, Montreal, QC, Canada.

Genetic markers of the endocannabinoid system have been linked to a variety of addiction-related behaviors that extend beyond cannabis use. In the current study we investigate the relationship between endocannabinoid (eCB) genetic markers and alcohol use disorder (AUD) in European adolescents (14-18 years old) followed in the IMAGEN study ( = 2,051) and explore replication in a cohort of North American adolescents from Canadian Saguenay Youth Study (SYS) ( = 772). Case-control status is represented by a score of more than 7 on the Alcohol Use Disorder Identification Test (AUDIT). Read More

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Bosonic condensation of exciton-polaritons in an atomically thin crystal.

Nat Mater 2021 May 6. Epub 2021 May 6.

Technische Physik and Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, Würzburg, Germany.

The emergence of two-dimensional crystals has revolutionized modern solid-state physics. From a fundamental point of view, the enhancement of charge carrier correlations has sparked much research activity in the transport and quantum optics communities. One of the most intriguing effects, in this regard, is the bosonic condensation and spontaneous coherence of many-particle complexes. Read More

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Fast crystal growth at ultra-low temperatures.

Nat Mater 2021 May 6. Epub 2021 May 6.

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

It is believed that the slow liquid diffusion and geometric frustration brought by a rapid, deep quench inhibit fast crystallization and promote vitrification. Here we report fast crystal growth in charged colloidal systems under deep supercooling, where liquid diffusion is extremely low. By combining experiments and simulations, we show that this process occurs via wall-induced barrierless ordering consisting of two coupled steps: the step-like advancement of the rough interface that disintegrates frustration, followed by defect repairing inside the newly formed solid phase. Read More

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Endo-microscopy beyond the Abbe and Nyquist limits.

Light Sci Appl 2020 May 7;9(1):81. Epub 2020 May 7.

LaserLaB, Department of Physics and Astronomy, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV, Amsterdam, The Netherlands.

For several centuries, far-field optical microscopy has remained a key instrument in many scientific disciplines, including physical, chemical, and biomedical research. Nonetheless, far-field imaging has many limitations: the spatial resolution is controlled by the diffraction of light, and the imaging speed follows the Nyquist-Shannon sampling theorem. The recent development of super-resolution techniques has pushed the limits of spatial resolution. Read More

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