Physics Reports最新文献

{"title":"Twenty Hopf-like bifurcations in piecewise-smooth dynamical systems","authors":"D.J.W. Simpson","doi":"10.1016/j.physrep.2022.04.007","DOIUrl":"https://doi.org/10.1016/j.physrep.2022.04.007","url":null,"abstract":"<div><p>For many physical systems the transition from a stationary solution to sustained small amplitude oscillations corresponds to a Hopf bifurcation. For systems involving impacts, thresholds, switches, or other abrupt events, however, this transition can be achieved in fundamentally different ways. This paper reviews 20 such ‘Hopf-like’ bifurcations for two-dimensional ODE systems with state-dependent switching rules. The bifurcations include boundary equilibrium bifurcations, the collision or change of stability of equilibria or folds on switching manifolds, and limit cycle creation via hysteresis or time delay. In each case a stationary solution changes stability and possibly form, and emits one limit cycle. Each bifurcation is analysed quantitatively in a general setting: we identify quantities that govern the onset, criticality, and genericity of the bifurcation, and determine scaling laws for the period and amplitude of the resulting limit cycle. Complete derivations based on asymptotic expansions of Poincaré maps are provided. Many of these are new, done previously only for piecewise-linear systems. The bifurcations are collated and compared so that dynamical observations can be matched to geometric mechanisms responsible for the creation of a limit cycle. The results are illustrated with impact oscillators, relay control, automated balancing control, predator–prey systems, ocean circulation, and the McKean and Wilson–Cowan neuron models.</p></div>","PeriodicalId":404,"journal":{"name":"Physics Reports","volume":"970 ","pages":"Pages 1-80"},"PeriodicalIF":30.0,"publicationDate":"2022-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"2890703","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Recanalization rate of proximal deep venous thrombosis related to therapeutic modality during six months follow-up.","authors":"Alden Begić, Edin Begić, Mirza Dilić, Svjetlana Loga-Zec, Nermina Babić, Refet Gojak, Armin Šljivo","doi":"10.17392/1451-22","DOIUrl":"10.17392/1451-22","url":null,"abstract":"<p><p>Aim To evaluate the efficacy (rate of recanalization) of therapy with novel oral anticoagulants (NOAC; rivaroxaban, apixaban) compared to conventional treatment (low molecular weight heparin - LMWH and vitamin K antagonist) in the treatment of deep vein thrombosis (DVT) of the proximal segments of lower extremities. Methods The first group consisted of patients diagnosed with DVT and treated with NOAC (n = 100), while the second group consisted of patients diagnosed with DVT, who were treated by conventional treatment (low molecular weight heparin and vitamin K antagonists) (n = 100). In the first group, NOAC was included in the initial treatment. Patients in the second group were treated with LMWH for four days, and on the fifth day vitamin K antagonist was included in therapy, international ratio (INR) was titrated to therapeutic values (2.0-3.0), and then low molecular weight heparin was excluded from the therapy. Results There was a statistically significant difference in the estimated values of free lumen of the blood vessel between the examined groups after 30 days (p=0.0001), after 90 days (p=0.0001) and after 180 days (p=0.0001). After 180 days, the average free lumen values in the NOAC group were 85% (81-89%), which was significantly higher than the free lumen values in the second group, 73% (69-79%). Conclusion The use of NOAC represents more efficient treatment of DVT comparing to vitamin K antagonists.</p>","PeriodicalId":404,"journal":{"name":"Physics Reports","volume":"468 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72440985","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dispersive πK→πK and ππ→KK̄ amplitudes from scattering data, threshold parameters, and the lightest strange resonance κ or K0∗(700)","authors":"José R. Peláez ,&nbsp;Arkaitz Rodas","doi":"10.1016/j.physrep.2022.03.004","DOIUrl":"https://doi.org/10.1016/j.physrep.2022.03.004","url":null,"abstract":"<div><p>We discuss the simultaneous dispersive analyses of <span><math><mrow><mi>π</mi><mi>K</mi><mo>→</mo><mi>π</mi><mi>K</mi></mrow></math></span> and <span><math><mrow><mi>π</mi><mi>π</mi><mo>→</mo><mi>K</mi><mover><mrow><mi>K</mi></mrow><mrow><mo>̄</mo></mrow></mover></mrow></math></span> scattering data and the <span><math><mrow><mi>κ</mi><mo>/</mo><msubsup><mrow><mi>K</mi></mrow><mrow><mn>0</mn></mrow><mrow><mo>∗</mo></mrow></msubsup><mrow><mo>(</mo><mn>700</mn><mo>)</mo></mrow></mrow></math></span> resonance. The unprecedented statistics of present and future hadron experiments, modern lattice QCD calculations, and the wealth of new states and decays require such precise and model-independent analyses to describe final state interactions. We review the existing and often conflicting data and explain in detail the derivation of the relevant dispersion relations, maximizing their applicability range. Next, we review and extend the caveats on some data, showing their inconsistency with dispersion relations. Our main result is the derivation and compilation of precise amplitude parameterizations constrained by several <span><math><mrow><mi>π</mi><mi>K</mi><mo>→</mo><mi>π</mi><mi>K</mi></mrow></math></span> and <span><math><mrow><mi>π</mi><mi>π</mi><mo>→</mo><mi>K</mi><mover><mrow><mi>K</mi></mrow><mrow><mo>̄</mo></mrow></mover></mrow></math></span> dispersion relations. These constrained parameterizations are easily implementable and provide the rigor and accuracy needed for modern experimental and phenomenological hadron physics. As applications, after reviewing their status and interest, we will provide new precise threshold and subthreshold parameters and review our dispersive determination of the controversial <span><math><mrow><mi>κ</mi><mo>/</mo><msubsup><mrow><mi>K</mi></mrow><mrow><mn>0</mn></mrow><mrow><mo>∗</mo></mrow></msubsup><mrow><mo>(</mo><mn>700</mn><mo>)</mo></mrow></mrow></math></span> resonance and other light-strange resonances.</p></div>","PeriodicalId":404,"journal":{"name":"Physics Reports","volume":"969 ","pages":"Pages 1-126"},"PeriodicalIF":30.0,"publicationDate":"2022-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"3339713","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Forward Physics Facility: Sites, experiments, and physics potential","authors":"Luis A. Anchordoqui ,&nbsp;Akitaka Ariga ,&nbsp;Tomoko Ariga ,&nbsp;Weidong Bai ,&nbsp;Kincso Balazs ,&nbsp;Brian Batell ,&nbsp;Jamie Boyd ,&nbsp;Joseph Bramante ,&nbsp;Mario Campanelli ,&nbsp;Adrian Carmona ,&nbsp;Francesco G. Celiberto ,&nbsp;Grigorios Chachamis ,&nbsp;Matthew Citron ,&nbsp;Giovanni De Lellis ,&nbsp;Albert De Roeck ,&nbsp;Hans Dembinski ,&nbsp;Peter B. Denton ,&nbsp;Antonia Di Crecsenzo ,&nbsp;Milind V. Diwan ,&nbsp;Liam Dougherty ,&nbsp;Yue Zhang","doi":"10.1016/j.physrep.2022.04.004","DOIUrl":"https://doi.org/10.1016/j.physrep.2022.04.004","url":null,"abstract":"<div><p>The Forward Physics Facility (FPF) is a proposal to create a cavern with the space and infrastructure to support a suite of far-forward experiments at the Large Hadron Collider during the High Luminosity era. Located along the beam collision axis and shielded from the interaction point by at least 100 m of concrete and rock, the FPF will house experiments that will detect particles outside the acceptance of the existing large LHC experiments and will observe rare and exotic processes in an extremely low-background environment. In this work, we summarize the current status of plans for the FPF, including recent progress in civil engineering in identifying promising sites for the FPF and the experiments currently envisioned to realize the FPF’s physics potential. We then review the many Standard Model and new physics topics that will be advanced by the FPF, including searches for long-lived particles, probes of dark matter and dark sectors, high-statistics studies of TeV neutrinos of all three flavors, aspects of perturbative and non-perturbative QCD, and high-energy astroparticle physics.</p></div>","PeriodicalId":404,"journal":{"name":"Physics Reports","volume":"968 ","pages":"Pages 1-50"},"PeriodicalIF":30.0,"publicationDate":"2022-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"1628399","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mass dimension one fermions: Constructing darkness","authors":"Dharam Vir Ahluwalia ,&nbsp;Julio M. Hoff da Silva ,&nbsp;Cheng-Yang Lee ,&nbsp;Yu-Xiao Liu ,&nbsp;Saulo H. Pereira ,&nbsp;Masoumeh Moazzen Sorkhi","doi":"10.1016/j.physrep.2022.04.003","DOIUrl":"https://doi.org/10.1016/j.physrep.2022.04.003","url":null,"abstract":"&lt;div&gt;&lt;p&gt;Let &lt;span&gt;&lt;math&gt;&lt;mi&gt;Θ&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; be the Wigner time reversal operator for spin half and let &lt;span&gt;&lt;math&gt;&lt;mi&gt;ϕ&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; be a Weyl spinor. Then, for a left-transforming &lt;span&gt;&lt;math&gt;&lt;mi&gt;ϕ&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt;, the construct &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;ζ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;λ&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mi&gt;Θ&lt;/mi&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mi&gt;ϕ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;∗&lt;/mo&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; yields a right-transforming spinor. If instead, &lt;span&gt;&lt;math&gt;&lt;mi&gt;ϕ&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; is a right-transforming spinor, then the construct &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;ζ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;ρ&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mi&gt;Θ&lt;/mi&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mi&gt;ϕ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;∗&lt;/mo&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; results in a left-transforming spinor (&lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;ζ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;λ&lt;/mi&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;mi&gt;ρ&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; are phase factors). This allows us to introduce two sets of four-component spinors. Setting &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;ζ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;λ&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; and &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;ζ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;ρ&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; to &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mo&gt;±&lt;/mo&gt;&lt;mi&gt;i&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; renders all eight spinors as eigenspinor of the charge conjugation operator &lt;span&gt;&lt;math&gt;&lt;mi&gt;C&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; (called ELKO). This allows us to introduce two quantum fields. A calculation of the vacuum expectation value of the time-ordered product of the fields and their adjoints reveals the mass dimension of the fields to be one. Both fields are local in the canonical sense of quantum field theory. Interestingly, one of the fields is fermionic and the other bosonic. The mass dimension of the introduced fermionic fields and the matter fields of the Standard Model carry an intrinsic mismatch. As such, they provide natural darkness for the new fields with respect to the Standard Model doublets. The statistics and locality are controlled by a set of phases. These are explicitly given. Then we observe that in &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;p&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;μ&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mi&gt;p&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;μ&lt;/mi&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;= m&lt;span&gt;&lt;math&gt;&lt;msup&gt;&lt;mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/math&gt;&lt;/span&gt;, Dirac took the simplest square root of the 4 × 4 identity matrix &lt;span&gt;&lt;math&gt;&lt;mi&gt;I&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; (in &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;I&lt;/mi&gt;&lt;mo&gt;×&lt;/mo&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;m&lt;span&gt;&lt;math&gt;&lt;msup&gt;&lt;mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/math&gt;&lt;/span&gt;, while introducing &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;γ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;μ&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mi&gt;p&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;μ&lt;/mi&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; as the square root of the left hand side of the dispersion relation), and as such he implicitly ignored the remaining fifteen. When we examine the remaining roots, we obtain additional bosonic and fermionic dark matter candidates of spin half. We point out that by early nineteen seventies, Dirac had suspected the existence of spin","PeriodicalId":404,"journal":{"name":"Physics Reports","volume":"967 ","pages":"Pages 1-43"},"PeriodicalIF":30.0,"publicationDate":"2022-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"3207068","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Extreme events in dynamical systems and random walkers: A review","authors":"Sayantan Nag Chowdhury ,&nbsp;Arnob Ray ,&nbsp;Syamal K. Dana ,&nbsp;Dibakar Ghosh","doi":"10.1016/j.physrep.2022.04.001","DOIUrl":"https://doi.org/10.1016/j.physrep.2022.04.001","url":null,"abstract":"<div><p>Extreme events gain the attention of researchers due to their utmost importance in various contexts ranging from climate to brain. An observable that deviates significantly from its long-time average will have adverse consequences for the system. This brings such recurrent events to the limelight of attention in interdisciplinary research. There is a need for research efforts in many systems in the real world to find solutions that can predict and mitigate the unfavorable effects of these recurring events. A comprehensive review of recent progress is provided to capture recent improvements in analyzing such very high-amplitude events from the point of view of dynamical systems and random walkers. We emphasize, in detail, the mechanisms responsible for the emergence of such events in complex systems. Several mechanisms that contribute to the occurrence of extreme events have been elaborated that investigate the sources of instabilities leading to them. In addition, we discuss the prediction of extreme events from two different contexts, using dynamical instabilities and data-based machine learning algorithms. Tracking of instabilities in the phase space is not always feasible and a precise knowledge of the dynamics of extreme events does not necessarily help in forecasting extreme events. Moreover, in most of the studies on high-dimensional systems, only a few degrees of freedom participate in extreme events’ formation. Thus, a notable inclusion of prediction through machine learning is of enormous significance, particularly for those cases where the governing equations of the model are explicitly unavailable. Besides, random walks on complex networks can represent several transport processes, and exceedances of the flux of walkers above a prescribed threshold may describe extreme events. We unveil theoretical studies on random walkers with their enormous potential for applications in reducing extreme events. We cover the possible controlling strategies, which may be helpful to mitigate extreme events in physical situations like traffic jams, heavy load of web requests, competition for shared resources, floods in the network of rivers, and many more. This review presents an overview of the current trend of research on extreme events in dynamical systems and networks, including random walkers, and discusses future possibilities. We conclude this review with an extended outlook and compelling perspective, along with the non-trivial challenges for further investigation.</p></div>","PeriodicalId":404,"journal":{"name":"Physics Reports","volume":"966 ","pages":"Pages 1-52"},"PeriodicalIF":30.0,"publicationDate":"2022-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"3207069","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quantum magnonics: When magnon spintronics meets quantum information science","authors":"H.Y. Yuan ,&nbsp;Yunshan Cao ,&nbsp;Akashdeep Kamra ,&nbsp;Rembert A. Duine ,&nbsp;Peng Yan","doi":"10.1016/j.physrep.2022.03.002","DOIUrl":"https://doi.org/10.1016/j.physrep.2022.03.002","url":null,"abstract":"<div><p>Spintronics and quantum information science are two promising candidates for innovating information processing technologies. The combination of these two fields enables us to build solid-state platforms for studying quantum phenomena and for realizing multi-functional quantum tasks. For a long time, however, the intersection of these two fields was limited due to the distinct properties of the classical magnetization, that is manipulated in spintronics, and quantum bits, that are utilized in quantum information science. This situation has changed significantly over the last few years because of the remarkable progress in coding and processing information using magnons. On the other hand, significant advances in understanding the entanglement of quasi-particles and in designing high-quality qubits and photonic cavities for quantum information processing provide physical platforms to integrate magnons with quantum systems. From these endeavours, the highly interdisciplinary field of quantum magnonics emerges, which combines spintronics, quantum optics and quantum information science. Here, we give an overview of the recent developments concerning the quantum states of magnons and their hybridization with mature quantum platforms. First, we review the basic concepts of magnons and quantum entanglement and discuss the generation and manipulation of quantum states of magnons, such as single-magnon states, squeezed states and quantum many-body states including Bose–Einstein condensation and the resulting spin superfluidity. We discuss how magnonic systems can be integrated and entangled with quantum platforms including cavity photons, superconducting qubits, nitrogen-vacancy centers, and phonons for coherent information transfer and collaborative information processing. The implications of these hybrid quantum systems for non-Hermitian physics and parity-time symmetry are highlighted, together with applications in quantum memories and high-precision measurements. Finally, we present an outlook on some of the challenges and opportunities in quantum magnonics.</p></div>","PeriodicalId":404,"journal":{"name":"Physics Reports","volume":"965 ","pages":"Pages 1-74"},"PeriodicalIF":30.0,"publicationDate":"2022-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"1629181","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Pentagon-based 2D materials: Classification, properties and applications","authors":"Yiheng Shen,&nbsp;Qian Wang","doi":"10.1016/j.physrep.2022.03.003","DOIUrl":"https://doi.org/10.1016/j.physrep.2022.03.003","url":null,"abstract":"<div><p><span><span><span>Since penta-graphene (PG), a two-dimensional (2D) carbon allotrope exclusively composed of five-membered rings, was proposed in 2015, a great deal of effort has been devoted to the rational design and synthesis of pentagon-based 2D materials with novel properties and promising applications. As a result, over one hundred new pentagonal 2D materials have been theoretically predicated, and some of them have been experimentally synthesized. Due to the unique geometries of these materials, they exhibit many interesting properties, including negative Poisson’s ratio, intrinsic </span>piezoelectricity, giant out-of-plane </span>second harmonic generation<span> susceptibility, ferromagnetism<span><span> with high Curie temperature and topological quantum state, and have broad applications. In this paper, we review the recent progress made in this emerging field, and classify all the pentagon-based 2D structures reported so far based on their geometric characteristics and space groups. Especially, we highlight the major breakthroughs that have occurred over the past several years, discuss the unexpected physical properties that have enabled these materials to bridge many disciplines in science and technology, and analyze the potential applications in metal-ion batteries, </span>thermoelectricity<span>, photocatalysis, electrocatalysis, and </span></span></span></span>heterojunction. The challenges and opportunities in this field are also discussed for future study.</p></div>","PeriodicalId":404,"journal":{"name":"Physics Reports","volume":"964 ","pages":"Pages 1-42"},"PeriodicalIF":30.0,"publicationDate":"2022-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"3339715","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quantifying relevance in learning and inference","authors":"Matteo Marsili ,&nbsp;Yasser Roudi","doi":"10.1016/j.physrep.2022.03.001","DOIUrl":"https://doi.org/10.1016/j.physrep.2022.03.001","url":null,"abstract":"<div><p>Learning is a distinctive feature of intelligent behaviour. High-throughput experimental data and Big Data promise to open new windows on complex systems such as cells, the brain or our societies. Yet, the puzzling success of Artificial Intelligence and Machine Learning shows that we still have a poor conceptual understanding of learning. These applications push statistical inference into uncharted territories where data is high-dimensional and scarce, and prior information on “true” models is scant if not totally absent. Here we review recent progress on understanding learning, based on the notion of “relevance”. The relevance, as we define it here, quantifies the amount of information that a dataset or the internal representation of a learning machine contains on the generative model of the data. This allows us to define maximally informative samples, on one hand, and optimal learning machines on the other. These are ideal limits of samples and of machines, that contain the maximal amount of information about the unknown generative process, at a given resolution (or level of compression). Both ideal limits exhibit critical features in the statistical sense: Maximally informative samples are characterised by a power-law frequency distribution (statistical criticality) and optimal learning machines by an anomalously large susceptibility. The trade-off between resolution (i.e. compression) and relevance distinguishes the regime of noisy representations from that of lossy compression. These are separated by a special point characterised by Zipf’s law statistics. This identifies samples obeying Zipf’s law as the most compressed loss-less representations that are optimal in the sense of maximal relevance. Criticality in optimal learning machines manifests in an exponential degeneracy of energy levels, that leads to unusual thermodynamic properties. This distinctive feature is consistent with the invariance of the classification under coarse graining of the output, which is a desirable property of learning machines. This theoretical framework is corroborated by empirical analysis showing (i) how the concept of relevance can be useful to identify relevant variables in high-dimensional inference and (ii) that widely used machine learning architectures approach reasonably well the ideal limit of optimal learning machines, within the limits of the data with which they are trained.</p></div>","PeriodicalId":404,"journal":{"name":"Physics Reports","volume":"963 ","pages":"Pages 1-43"},"PeriodicalIF":30.0,"publicationDate":"2022-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"1629182","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"High contrast 3-D optical bioimaging using molecular and nanoprobes optically responsive to IR light","authors":"Jun Qian ,&nbsp;Zhe Feng ,&nbsp;Xiaoxiao Fan ,&nbsp;Andrey Kuzmin ,&nbsp;Anderson S.L. Gomes ,&nbsp;Paras N. Prasad","doi":"10.1016/j.physrep.2022.02.004","DOIUrl":"https://doi.org/10.1016/j.physrep.2022.02.004","url":null,"abstract":"<div><p><span><span><span>Biophotonics is a convergent field which integrates biological physics, </span>neurosciences, </span>optical physics<span>, and nanoscience for optical diagnostics, bioimaging and light activated therapies, with no tissue invasion and free of </span></span>ionizing radiation. It is expected to play an important role in advancing the emerging field of molecular medicine by yielding detailed information on structures and dynamics at subcellular levels.</p><p><span>This review, truly interdisciplinary and unique in its scope, highlights the integrated roles of the above-named disciplines for advancing IR bioimaging, aiming to attract a broad cross-section of readership of Physics Reports, and is written with multinational authorship to bring out a global perspective. A unique feature of this review is its comprehensive coverage of a multitude of the various optical bioimaging modalities, their physics principles, their relative merits, and their complementarity. Specifically covered themes are fluorescence imaging, nonlinear optical imaging<span><span>, photoacoustic imaging, optical coherence tomography (OCT) and hyperspectral imaging. The review first discusses light propagation and bio-optics of processes of </span>light absorption, scattering and transmission in biological media. It describes the various biological spectral windows of maximum optical transparencies which are suitable for optical imaging. Then, we introduce the different optical imaging modalities and their features in bioimaging both </span></span><em>in vitro</em> and <em>in vivo</em>. The role of molecular and nano-probes to serve as contrast agents for different modalities of imaging is described. A unique aspect also discussed in this review is the physics of manipulation of excitation dynamics that can make them selectively nanoemitters for fluorescence imaging; nonlinear optical probes for imaging; nano-photothermal heaters and nanothermometry for photoacoustic imaging; and nanoscatterers for OCT. As selected emerging applications, we describe imaging-guided theranostics as well as applications in novel areas of neurophotonics and nanodentistry. Finally, the review concludes by presenting current challenges and our views on future opportunities aimed to stimulate further research in this field of high societal impact.</p></div>","PeriodicalId":404,"journal":{"name":"Physics Reports","volume":"962 ","pages":"Pages 1-107"},"PeriodicalIF":30.0,"publicationDate":"2022-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"1613221","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}