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A Thermodynamic Comparison of Nanotip and Nanoblade Geometries for Ultrafast Laser Field Emission via the Finite Element Method 通过有限元法对超快激光场发射的纳米尖端和纳米叶片几何形状进行热力学比较
IF 1.6
Physics Pub Date : 2023-12-19 DOI: 10.3390/physics6010001
J. Mann, James Rosenzweig
{"title":"A Thermodynamic Comparison of Nanotip and Nanoblade Geometries for Ultrafast Laser Field Emission via the Finite Element Method","authors":"J. Mann, James Rosenzweig","doi":"10.3390/physics6010001","DOIUrl":"https://doi.org/10.3390/physics6010001","url":null,"abstract":"Strong laser field emission from metals is a growing area of study, owing to its applications in high-brightness cathodes and potentially as a high harmonic generation source. Nanopatterned plasmonic cathodes localize and enhance incident laser fields, reducing the spot size and increasing the current density. Experiments have demonstrated that the nanoblade structure outperforms nanotips in the peak fields achieved before damage is inflicted. With more intense surface fields come brighter emissions, and thus investigating the thermomechanical properties of these structures is crucial in their characterization. We study, using the finite element method, the electron and lattice temperatures for varying geometries, as well as the opening angles, peak surface fields, and apex radii of curvature. While we underestimate the energy deposited into the lattice here, a comparison of the geometries is still helpful for understanding why one structure performs better than the other. We find that the opening angle—not the structure dimensionality—is what primarily determines the thermal performance of these structures.","PeriodicalId":20136,"journal":{"name":"Physics","volume":" 43","pages":""},"PeriodicalIF":1.6,"publicationDate":"2023-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138962652","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Vacuum Interaction of Topological Strings at Short Distances 拓扑弦在短距离上的真空相互作用
IF 1.6
Physics Pub Date : 2023-12-14 DOI: 10.3390/physics5040075
Y. Grats, P. Spirin
{"title":"Vacuum Interaction of Topological Strings at Short Distances","authors":"Y. Grats, P. Spirin","doi":"10.3390/physics5040075","DOIUrl":"https://doi.org/10.3390/physics5040075","url":null,"abstract":"The paper provides an extended overview of recent results obtained by the authors in the process of studying the vacuum interaction of topological cosmic strings at short distances, taking into account their transverse size a and the mass m of the quantized field. We consider the case of a massive real-valued scalar field with minimal coupling. It is shown that at the interstring distances significantly larger than the Compton length, lc=1/m, the Casimir effect is damped exponentially. On the other hand, at distances smaller than lc but much larger than the typical string width, the field-mass influence becomes insignificant. In this case, the partial contribution of a massive field to the Casimir energy is of the same order as the contribution of a massless one. At these distances, the string’s transverse size is insignificant also. However, at the interstring distances of the same order as a string radius, the energy of the vacuum interaction of thick strings may significantly surpass the one for two infinitely thin strings with the same mass per unit length.","PeriodicalId":20136,"journal":{"name":"Physics","volume":"50 6","pages":""},"PeriodicalIF":1.6,"publicationDate":"2023-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139003111","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Theory of Liquids for Studying the Conformational Flexibility of Biomolecules with Reference Interaction Site Model Approximation 利用参考相互作用位点模型近似研究生物大分子构象柔性的液体理论
IF 1.6
Physics Pub Date : 2023-12-13 DOI: 10.3390/physics5040073
Alexey Danilkovich, Dmitry Tikhonov
{"title":"Theory of Liquids for Studying the Conformational Flexibility of Biomolecules with Reference Interaction Site Model Approximation","authors":"Alexey Danilkovich, Dmitry Tikhonov","doi":"10.3390/physics5040073","DOIUrl":"https://doi.org/10.3390/physics5040073","url":null,"abstract":"The theory of fluids is used to modify the integral equations of the reference interaction site model (RISM) approximation. Its applicability to the study of biomolecules solvation is evaluated. Unlike traditional RISM applications, the new integral equation contains an intramolecular correlation matrix that only needs to be calculated once. This allows us to bypass the effort of repeatedly solving RISM equations and the time-consuming averaging of values obtained for each time point of a molecular trajectory. The new approach allows for the assessment of the conformational transience of dissolved molecules while taking into account the effects of solvation. The free energy of oxytocin, which is a peptide hormone, as well as self-assembled ionic peptide complexes calculated using both the traditional RISM and the new RISM with average matrix (RISM-AM) approach are estimated. The free energy of oxytocin calculated using RISM-AM shows that the statistical error does not exceed the error obtained by standard averaging of solutions in the RISM equation. Despite the somewhat ambiguous results obtained for ionic peptide self-assembly using RISM-AM with Lennard–Jones repulsion correction, this method can still be considered applicable for fast molecular dynamics analysis. Since the required computational power can be reduced by at least two orders of magnitude, the medium-matrix RISM is indeed a highly applicable tool for studying macromolecular conformations as well as corresponding solvation effects.","PeriodicalId":20136,"journal":{"name":"Physics","volume":"29 2","pages":""},"PeriodicalIF":1.6,"publicationDate":"2023-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139004884","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Optical Properties of Two Complementary Samples of Intermediate Seyfert Galaxies 中间塞弗特星系两个互补样品的光学性质
Physics Pub Date : 2023-11-14 DOI: 10.3390/physics5040069
Benedetta Dalla Barba, Marco Berton, Luigi Foschini, Giovanni La Mura, Amelia Vietri, Stefano Ciroi
{"title":"Optical Properties of Two Complementary Samples of Intermediate Seyfert Galaxies","authors":"Benedetta Dalla Barba, Marco Berton, Luigi Foschini, Giovanni La Mura, Amelia Vietri, Stefano Ciroi","doi":"10.3390/physics5040069","DOIUrl":"https://doi.org/10.3390/physics5040069","url":null,"abstract":"We present first results of the analysis of optical spectra of two complementary samples of Seyfert galaxies (Seyferts). The first sample was extracted from a selection of the 4th Fermi Gamma-ray Large Area Telescope (4FGL) catalog and consists of 11 γ-ray-emitting jetted Seyfert galaxies. The second one was extracted from the Swift-BAT AGN Spectroscopic Survey (BASS) and is composed of 38 hard-X-ray-selected active galactic nuclei (AGN). These two samples are complementary, with the former being expected to have smaller viewing angles, while the latter may include objects with larger viewing angles. We measured emission-line ratios to investigate whether the behavior of these Seyferts can be explained in terms of obscuration, as suggested by the Unified Model (UM) of AGN, or if there are intrinsic differences due to the presence of jets or outflows, or due to evolution. We found no indications of intrinsic differences. The UM remains the most plausible interpretation for these classes of objects, even if some results can be challenging for this model.","PeriodicalId":20136,"journal":{"name":"Physics","volume":"16 9","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134900970","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Single-Spin Asymmetry of Neutrons in Polarized pA Collisions 偏振pA碰撞中中子的单自旋不对称性
Physics Pub Date : 2023-11-07 DOI: 10.3390/physics5040068
Boris Z. Kopeliovich, Irina K. Potashnikova, Iván Schmidt
{"title":"Single-Spin Asymmetry of Neutrons in Polarized pA Collisions","authors":"Boris Z. Kopeliovich, Irina K. Potashnikova, Iván Schmidt","doi":"10.3390/physics5040068","DOIUrl":"https://doi.org/10.3390/physics5040068","url":null,"abstract":"Absorptive corrections, which are known to suppress proton-neutron transitions with a large fractional momentum z→1 in pp collisions, become dramatically strong on a nuclear target, and they push the partial cross sections of leading neutron production to the very periphery of the nucleus. The mechanism of the pion π and axial vector meson a1 interference, which successfully explains the observed single-spin asymmetry in a polarized pp→nX, is extended to the collisions of polarized protons with nuclei. When corrected for nuclear effects, it explains the observed single-spin azimuthal asymmetry of neutrons that is produced in inelastic events, which is where the nucleus violently breaks up. This single-spin asymmetry is found to be negative and nearly atomic mass number A-independent.","PeriodicalId":20136,"journal":{"name":"Physics","volume":"43 179","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135540150","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Phase Diagram for Social Impact Theory in Initially Fully Differentiated Society 初步完全分化社会中社会影响理论的阶段图
Physics Pub Date : 2023-10-27 DOI: 10.3390/physics5040067
Krzysztof Malarz, Tomasz Masłyk
{"title":"Phase Diagram for Social Impact Theory in Initially Fully Differentiated Society","authors":"Krzysztof Malarz, Tomasz Masłyk","doi":"10.3390/physics5040067","DOIUrl":"https://doi.org/10.3390/physics5040067","url":null,"abstract":"The study of opinion formation and dynamics is one of the core topics in sociophysics. In this paper, the results of computer simulation of opinion dynamics based on social impact theory are presented. The simulations are based on Latané theory in its computerised version proposed by Nowak, Szamrej and Latané. The active parameters of the model describe the volatility of the actors (social temperature T) and the effective range of interaction (governed by an exponent α in a scaling function of distance between actors). Initially, every actor i has his/her own opinion. Our results indicate that ultimately at least 90% of the initial opinions available are removed from the society. For a low social temperature and a long range of interaction, only one opinion survives. Also, a rough sketch of the system phase diagram is presented. It indicates a set of (α,T) leading either to (1) the dominance of the unanimity of the opinions or (2) mixtures of unanimity and polarisation, or (3) taking random opinions by actors, or (4) a mixture of the final fates of the systems. The drastic reduction of finally observed opinions vs. their initial variety may be generic for many sociophysical models of opinions formation but masked by assuming an initially small pool of available opinions (in the worst case, in models with only binary opinions).","PeriodicalId":20136,"journal":{"name":"Physics","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136235066","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
How a Piece of Roman Glass Became a Photonic Crystal 一块罗马玻璃是如何变成光子晶体的
Physics Pub Date : 2023-10-17 DOI: 10.1103/physics.16.180
Charles Day
{"title":"How a Piece of Roman Glass Became a Photonic Crystal","authors":"Charles Day","doi":"10.1103/physics.16.180","DOIUrl":"https://doi.org/10.1103/physics.16.180","url":null,"abstract":"","PeriodicalId":20136,"journal":{"name":"Physics","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135994482","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Intense X Rays Can Free Bound Electrons 强X射线能使束缚电子自由
Physics Pub Date : 2023-10-17 DOI: 10.1103/physics.16.s142
Rachel Berkowitz
{"title":"Intense X Rays Can Free Bound Electrons","authors":"Rachel Berkowitz","doi":"10.1103/physics.16.s142","DOIUrl":"https://doi.org/10.1103/physics.16.s142","url":null,"abstract":"T he x-ray free-electron laser (XFEL) is a revolutionary tool for investigating light–matter interactions. The quick-fire pulses of high-energy radiation used in this tool can capture a fast succession of snapshots of a material’s atoms, revealing the fine-scale, three-dimensional details of atomic movements without destroying a sample. Still, the intense irradiation of an XFEL has the potential to alter both the electronic and atomic configurations of a material, which complicates the determination of a solid’s structure. Now Ichiro Inoue of RIKEN in Japan and his colleagues have pinpointed when and how an XFEL’s pulses alter the crystal structures they are designed to reveal [1]. The results could help resolve limitations of the technology and could be used to improve accuracy in future XFEL imaging.","PeriodicalId":20136,"journal":{"name":"Physics","volume":"121-124 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135994777","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Safely Transporting Green Hydrogen 安全运输绿色氢
Physics Pub Date : 2023-10-16 DOI: 10.1103/physics.16.175
Wolfgang Bauer
{"title":"Safely Transporting Green Hydrogen","authors":"Wolfgang Bauer","doi":"10.1103/physics.16.175","DOIUrl":"https://doi.org/10.1103/physics.16.175","url":null,"abstract":"H umanity consumes approximately 100 million tons of hydrogen each year. The overwhelming majority of this hydrogen is used in various industrial processes, such as the production of ammonia. And we’re poised to use even more, as hydrogen can power engines and other machines without producing greenhouse gases. Still, for any large-scale transition to a clean fuel source, the fuel itself needs to be easily and economically stored and transported. Researchers at Los Alamos National Laboratory in NewMexico now analyze how to safely transport hydrogen in existing pipeline infrastructure [1]. Their study indicates possibilities to overcome challenges associated with introducing hydrogen gas into systems designed for natural gas transport (Fig. 1). The results show in particular that a hydrogen–natural gas mixture can bemanaged so as to avoid unwanted pressure spikes.","PeriodicalId":20136,"journal":{"name":"Physics","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136142949","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
The Skinny on Detecting Life with the JWST 用JWST探测生命的概要
Physics Pub Date : 2023-10-13 DOI: 10.1103/physics.16.178
Katherine Wright
{"title":"The Skinny on Detecting Life with the JWST","authors":"Katherine Wright","doi":"10.1103/physics.16.178","DOIUrl":"https://doi.org/10.1103/physics.16.178","url":null,"abstract":"The absorption spectrum of K2-18b’s atmosphere taken with the JWST’s instruments. The detections of methane and carbon dioxide—and the nondetection of ammonia—suggest the presence of an ocean underneath a hydrogen-rich atmosphere, according to planetary models. There’s also a hint of DMS, which on Earth is tied to biological activity.","PeriodicalId":20136,"journal":{"name":"Physics","volume":"131 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135919557","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
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