Pub Date : 2016-04-01DOI: 10.1088/0034-4885/79/4/040201
G. Baym
{"title":"Incoming Editor-in-Chief","authors":"G. Baym","doi":"10.1088/0034-4885/79/4/040201","DOIUrl":"https://doi.org/10.1088/0034-4885/79/4/040201","url":null,"abstract":"","PeriodicalId":21110,"journal":{"name":"Reports on Progress in Physics","volume":null,"pages":null},"PeriodicalIF":18.1,"publicationDate":"2016-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1088/0034-4885/79/4/040201","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72411741","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}
Pub Date : 2016-03-23DOI: 10.1088/0034-4885/79/4/046601
C. Creton, M. Ciccotti
Soft materials are materials with a low shear modulus relative to their bulk modulus and where elastic restoring forces are mainly of entropic origin. A sparse population of strong bonds connects molecules together and prevents macroscopic flow. In this review we discuss the current state of the art on how these soft materials break and detach from solid surfaces. We focus on how stresses and strains are localized near the fracture plane and how elastic energy can flow from the bulk of the material to the crack tip. Adhesion of pressure-sensitive-adhesives, fracture of gels and rubbers are specifically addressed and the key concepts are pointed out. We define the important length scales in the problem and in particular the elasto-adhesive length Γ/E where Γ is the fracture energy and E is the elastic modulus, and how the ratio between sample size and Γ/E controls the fracture mechanisms. Theoretical concepts bridging solid mechanics and polymer physics are rationalized and illustrated by micromechanical experiments and mechanisms of fracture are described in detail. Open questions and emerging concepts are discussed at the end of the review.
{"title":"Fracture and adhesion of soft materials: a review","authors":"C. Creton, M. Ciccotti","doi":"10.1088/0034-4885/79/4/046601","DOIUrl":"https://doi.org/10.1088/0034-4885/79/4/046601","url":null,"abstract":"Soft materials are materials with a low shear modulus relative to their bulk modulus and where elastic restoring forces are mainly of entropic origin. A sparse population of strong bonds connects molecules together and prevents macroscopic flow. In this review we discuss the current state of the art on how these soft materials break and detach from solid surfaces. We focus on how stresses and strains are localized near the fracture plane and how elastic energy can flow from the bulk of the material to the crack tip. Adhesion of pressure-sensitive-adhesives, fracture of gels and rubbers are specifically addressed and the key concepts are pointed out. We define the important length scales in the problem and in particular the elasto-adhesive length Γ/E where Γ is the fracture energy and E is the elastic modulus, and how the ratio between sample size and Γ/E controls the fracture mechanisms. Theoretical concepts bridging solid mechanics and polymer physics are rationalized and illustrated by micromechanical experiments and mechanisms of fracture are described in detail. Open questions and emerging concepts are discussed at the end of the review.","PeriodicalId":21110,"journal":{"name":"Reports on Progress in Physics","volume":null,"pages":null},"PeriodicalIF":18.1,"publicationDate":"2016-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79454630","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}
Pub Date : 2016-03-22DOI: 10.1088/0034-4885/79/4/046901
A. Marcowith, A. Bret, A. Bykov, M. Dieckman, L. Drury, B. Lembége, M. Lemoine, G. Morlino, G. Murphy, G. Pelletier, I. Plotnikov, B. Reville, M. Riquelme, L. Sironi, A. S. Novo
Collisionless shocks, that is shocks mediated by electromagnetic processes, are customary in space physics and in astrophysics. They are to be found in a great variety of objects and environments: magnetospheric and heliospheric shocks, supernova remnants, pulsar winds and their nebulæ, active galactic nuclei, gamma-ray bursts and clusters of galaxies shock waves. Collisionless shock microphysics enters at different stages of shock formation, shock dynamics and particle energization and/or acceleration. It turns out that the shock phenomenon is a multi-scale non-linear problem in time and space. It is complexified by the impact due to high-energy cosmic rays in astrophysical environments. This review adresses the physics of shock formation, shock dynamics and particle acceleration based on a close examination of available multi-wavelength or in situ observations, analytical and numerical developments. A particular emphasis is made on the different instabilities triggered during the shock formation and in association with particle acceleration processes with regards to the properties of the background upstream medium. It appears that among the most important parameters the background magnetic field through the magnetization and its obliquity is the dominant one. The shock velocity that can reach relativistic speeds has also a strong impact over the development of the micro-instabilities and the fate of particle acceleration. Recent developments of laboratory shock experiments has started to bring some new insights in the physics of space plasma and astrophysical shock waves. A special section is dedicated to new laser plasma experiments probing shock physics.
{"title":"The microphysics of collisionless shock waves","authors":"A. Marcowith, A. Bret, A. Bykov, M. Dieckman, L. Drury, B. Lembége, M. Lemoine, G. Morlino, G. Murphy, G. Pelletier, I. Plotnikov, B. Reville, M. Riquelme, L. Sironi, A. S. Novo","doi":"10.1088/0034-4885/79/4/046901","DOIUrl":"https://doi.org/10.1088/0034-4885/79/4/046901","url":null,"abstract":"Collisionless shocks, that is shocks mediated by electromagnetic processes, are customary in space physics and in astrophysics. They are to be found in a great variety of objects and environments: magnetospheric and heliospheric shocks, supernova remnants, pulsar winds and their nebulæ, active galactic nuclei, gamma-ray bursts and clusters of galaxies shock waves. Collisionless shock microphysics enters at different stages of shock formation, shock dynamics and particle energization and/or acceleration. It turns out that the shock phenomenon is a multi-scale non-linear problem in time and space. It is complexified by the impact due to high-energy cosmic rays in astrophysical environments. This review adresses the physics of shock formation, shock dynamics and particle acceleration based on a close examination of available multi-wavelength or in situ observations, analytical and numerical developments. A particular emphasis is made on the different instabilities triggered during the shock formation and in association with particle acceleration processes with regards to the properties of the background upstream medium. It appears that among the most important parameters the background magnetic field through the magnetization and its obliquity is the dominant one. The shock velocity that can reach relativistic speeds has also a strong impact over the development of the micro-instabilities and the fate of particle acceleration. Recent developments of laboratory shock experiments has started to bring some new insights in the physics of space plasma and astrophysical shock waves. A special section is dedicated to new laser plasma experiments probing shock physics.","PeriodicalId":21110,"journal":{"name":"Reports on Progress in Physics","volume":null,"pages":null},"PeriodicalIF":18.1,"publicationDate":"2016-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72768278","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}
Pub Date : 2016-03-22DOI: 10.1088/0034-4885/79/4/046501
A. Rogalski, P. Martyniuk, M. Kopytko
In the last two decades, several new concepts for improving the performance of infrared detectors have been proposed. These new concepts particularly address the drive towards the so-called high operating temperature focal plane arrays (FPAs), aiming to increase detector operating temperatures, and as a consequence reduce the cost of infrared systems. In imaging systems with the above megapixel formats, pixel dimension plays a crucial role in determining critical system attributes such as system size, weight and power consumption (SWaP). The advent of smaller pixels has also resulted in the superior spatial and temperature resolution of these systems. Optimum pixel dimensions are limited by diffraction effects from the aperture, and are in turn wavelength-dependent. In this paper, the key challenges in realizing optimum pixel dimensions in FPA design including dark current, pixel hybridization, pixel delineation, and unit cell readout capacity are outlined to achieve a sufficiently adequate modulation transfer function for the ultra-small pitches involved. Both photon and thermal detectors have been considered. Concerning infrared photon detectors, the trade-offs between two types of competing technology—HgCdTe material systems and III–V materials (mainly barrier detectors)—have been investigated.
{"title":"Challenges of small-pixel infrared detectors: a review","authors":"A. Rogalski, P. Martyniuk, M. Kopytko","doi":"10.1088/0034-4885/79/4/046501","DOIUrl":"https://doi.org/10.1088/0034-4885/79/4/046501","url":null,"abstract":"In the last two decades, several new concepts for improving the performance of infrared detectors have been proposed. These new concepts particularly address the drive towards the so-called high operating temperature focal plane arrays (FPAs), aiming to increase detector operating temperatures, and as a consequence reduce the cost of infrared systems. In imaging systems with the above megapixel formats, pixel dimension plays a crucial role in determining critical system attributes such as system size, weight and power consumption (SWaP). The advent of smaller pixels has also resulted in the superior spatial and temperature resolution of these systems. Optimum pixel dimensions are limited by diffraction effects from the aperture, and are in turn wavelength-dependent. In this paper, the key challenges in realizing optimum pixel dimensions in FPA design including dark current, pixel hybridization, pixel delineation, and unit cell readout capacity are outlined to achieve a sufficiently adequate modulation transfer function for the ultra-small pitches involved. Both photon and thermal detectors have been considered. Concerning infrared photon detectors, the trade-offs between two types of competing technology—HgCdTe material systems and III–V materials (mainly barrier detectors)—have been investigated.","PeriodicalId":21110,"journal":{"name":"Reports on Progress in Physics","volume":null,"pages":null},"PeriodicalIF":18.1,"publicationDate":"2016-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81873112","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}
Pub Date : 2016-03-22DOI: 10.1088/0034-4885/79/10/106501
N. Sinitsyn, Y. Pershin
Direct measurements of spin fluctuations are becoming the mainstream approach for studies of complex condensed matter, molecular, nuclear, and atomic systems. This review covers recent progress in the field of optical spin noise spectroscopy (SNS) with an additional goal to establish an introduction into its theoretical foundations. Various theoretical techniques that have been recently used to interpret results of SNS measurements are explained alongside examples of their applications.
{"title":"The theory of spin noise spectroscopy: a review","authors":"N. Sinitsyn, Y. Pershin","doi":"10.1088/0034-4885/79/10/106501","DOIUrl":"https://doi.org/10.1088/0034-4885/79/10/106501","url":null,"abstract":"Direct measurements of spin fluctuations are becoming the mainstream approach for studies of complex condensed matter, molecular, nuclear, and atomic systems. This review covers recent progress in the field of optical spin noise spectroscopy (SNS) with an additional goal to establish an introduction into its theoretical foundations. Various theoretical techniques that have been recently used to interpret results of SNS measurements are explained alongside examples of their applications.","PeriodicalId":21110,"journal":{"name":"Reports on Progress in Physics","volume":null,"pages":null},"PeriodicalIF":18.1,"publicationDate":"2016-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77347004","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}
Pub Date : 2016-03-22DOI: 10.1088/0034-4885/79/4/046401
A. Borisov, J. McCorkindale, S. Poopalasingam, J. Longworth, P. Simon, S. Szatmári, C. Rhodes
The trajectory of discovery associated with the study of high-intensity nonlinear radiative interactions with matter and corresponding nonlinear modes of electromagnetic propagation through material that have been conducted over the last 50 years can be presented as a landscape in the intensity/quantum energy [I-ħω] plane. Based on an extensive series of experimental and theoretical findings, a universal zone of anomalous enhanced electromagnetic coupling, designated as the fundamental nonlinear domain, can be defined. Since the lower boundaries of this region for all atomic matter correspond to ħω ~ 103 eV and I ≈ 1016 W cm−2, it heralds a future dominated by x-ray and γ-ray studies of all phases of matter including nuclear states. The augmented strength of the interaction with materials can be generally expressed as an increase in the basic electromagnetic coupling constant in which the fine structure constant α → Z2α, where Z denotes the number of electrons participating in an ordered response to the driving field. Since radiative conditions strongly favoring the development of this enhanced electromagnetic coupling are readily produced in self-trapped plasma channels, the processes associated with the generation of nonlinear interactions with materials stand in natural alliance with the nonlinear mechanisms that induce confined propagation. An experimental example involving the Xe (4d105s25p6) supershell for which Z ≅ 18 that falls in the specified anomalous nonlinear domain is described. This yields an effective coupling constant of Z2α ≅ 2.4 > 1, a magnitude comparable to the strong interaction and a value rendering as useless conventional perturbative analyses founded on an expansion in powers of α. This enhancement can be quantitatively understood as a direct consequence of the dominant role played by coherently driven multiply-excited states in the dynamics of the coupling. It is also conclusively demonstrated by an abundance of data that the utterly peerless champion of the experimental campaign leading to the definition of the fundamental nonlinear domain was excimer laser technology. The basis of this unique role was the ability to satisfy simultaneously a triplet (ω, I, P) of conditions stating the minimal values of the frequency ω, intensity I, and the power P necessary to enable the key physical processes to be experimentally observed and controllably combined. The historical confluence of these developments creates a solid foundation for the prediction of future advances in the fundamental understanding of ultra-high power density states of matter. The atomic findings graciously generalize to the composition of a nuclear stanza expressing the accessibility of the nuclear domain. With this basis serving as the launch platform, a cadenza of three grand challenge problems representing both new materials and new interactions is presented for future solution; they are (1) the performance of an experimental probe of the proper
在过去的50年里，与高强度非线性辐射与物质相互作用的研究以及电磁传播的相应非线性模式相关的发现轨迹可以在强度/量子能量[I-ħω]平面上呈现。基于一系列广泛的实验和理论发现，可以定义一个异常增强电磁耦合的通用区域，指定为基本非线性域。由于该区域所有原子物质的下边界对应于ħω ~ 103 eV和I≈1016 W cm−2，它预示着未来以x射线和γ射线研究为主导的物质包括核态的所有相。与材料相互作用强度的增强一般可以表示为基本电磁耦合常数的增加，其中精细结构常数α→Z2α，其中Z表示参与驱动场有序响应的电子数。由于有利于这种增强电磁耦合发展的辐射条件很容易在自困等离子体通道中产生，因此与材料产生非线性相互作用相关的过程与诱导受限传播的非线性机制自然结合。描述了一个涉及Xe (4d105s25p6)超壳层的实验实例，其中Z = 18落在指定的反常非线性域内。这就产生了一个有效的耦合常数Z2α = 2.4 > 1，其量级可与强相互作用相媲美，而其值则是建立在α的幂次展开基础上的无用的传统微扰分析。这种增强可以定量地理解为在耦合动力学中相干驱动的多重激发态所起的主导作用的直接结果。大量的数据也确凿地证明，在导致基本非线性域定义的实验运动中，绝对无与伦比的冠军是准分子激光技术。这一独特作用的基础是能够同时满足三个条件(ω， I, P)，这些条件说明了频率ω，强度I和功率P的最小值，从而使关键的物理过程能够通过实验观察和可控地组合。这些发展的历史汇合为预测超高功率密度物质状态的基本理解的未来进展奠定了坚实的基础。原子的发现优雅地推广到一个核节的组成，表达了核域的可及性。以这个基础作为启动平台，展示了代表新材料和新相互作用的三大挑战问题，以供未来解决;它们是:(1)在接近Schwinger/Heisenberg极限的强度下，对与暗能量相关的真空态性质的实验探测的性能，(2)在γ射线区域(~1 MeV)的放大的实现和核准分子的发现，以及(3)确定了通往预测的超重稳定核岛的路径。
{"title":"Rewriting the rules governing high intensity interactions of light with matter","authors":"A. Borisov, J. McCorkindale, S. Poopalasingam, J. Longworth, P. Simon, S. Szatmári, C. Rhodes","doi":"10.1088/0034-4885/79/4/046401","DOIUrl":"https://doi.org/10.1088/0034-4885/79/4/046401","url":null,"abstract":"The trajectory of discovery associated with the study of high-intensity nonlinear radiative interactions with matter and corresponding nonlinear modes of electromagnetic propagation through material that have been conducted over the last 50 years can be presented as a landscape in the intensity/quantum energy [I-ħω] plane. Based on an extensive series of experimental and theoretical findings, a universal zone of anomalous enhanced electromagnetic coupling, designated as the fundamental nonlinear domain, can be defined. Since the lower boundaries of this region for all atomic matter correspond to ħω ~ 103 eV and I ≈ 1016 W cm−2, it heralds a future dominated by x-ray and γ-ray studies of all phases of matter including nuclear states. The augmented strength of the interaction with materials can be generally expressed as an increase in the basic electromagnetic coupling constant in which the fine structure constant α → Z2α, where Z denotes the number of electrons participating in an ordered response to the driving field. Since radiative conditions strongly favoring the development of this enhanced electromagnetic coupling are readily produced in self-trapped plasma channels, the processes associated with the generation of nonlinear interactions with materials stand in natural alliance with the nonlinear mechanisms that induce confined propagation. An experimental example involving the Xe (4d105s25p6) supershell for which Z ≅ 18 that falls in the specified anomalous nonlinear domain is described. This yields an effective coupling constant of Z2α ≅ 2.4 > 1, a magnitude comparable to the strong interaction and a value rendering as useless conventional perturbative analyses founded on an expansion in powers of α. This enhancement can be quantitatively understood as a direct consequence of the dominant role played by coherently driven multiply-excited states in the dynamics of the coupling. It is also conclusively demonstrated by an abundance of data that the utterly peerless champion of the experimental campaign leading to the definition of the fundamental nonlinear domain was excimer laser technology. The basis of this unique role was the ability to satisfy simultaneously a triplet (ω, I, P) of conditions stating the minimal values of the frequency ω, intensity I, and the power P necessary to enable the key physical processes to be experimentally observed and controllably combined. The historical confluence of these developments creates a solid foundation for the prediction of future advances in the fundamental understanding of ultra-high power density states of matter. The atomic findings graciously generalize to the composition of a nuclear stanza expressing the accessibility of the nuclear domain. With this basis serving as the launch platform, a cadenza of three grand challenge problems representing both new materials and new interactions is presented for future solution; they are (1) the performance of an experimental probe of the proper","PeriodicalId":21110,"journal":{"name":"Reports on Progress in Physics","volume":null,"pages":null},"PeriodicalIF":18.1,"publicationDate":"2016-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83567931","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}
Pub Date : 2016-02-11DOI: 10.1088/1361-6633/80/2/026501
C. Reichhardt, C. Reichhardt
We review the depinning and nonequilibrium phases of collectively interacting particle systems driven over random or periodic substrates. This type of system is relevant to vortices in type-II superconductors, sliding charge density waves, electron crystals, colloids, stripe and pattern forming systems, and skyrmions, and could also have connections to jamming, glassy behaviors, and active matter. These systems are also ideal for exploring the broader issues of characterizing transient and steady state nonequilibrium flow phases as well as nonequilibrium phase transitions between distinct dynamical phases, analogous to phase transitions between different equilibrium states. We discuss the differences between elastic and plastic depinning on random substrates and the different types of nonequilibrium phases which are associated with specific features in the velocity-force curves, fluctuation spectra, scaling relations, and local or global particle ordering. We describe how these quantities can change depending on the dimension, anisotropy, disorder strength, and the presence of hysteresis. Within the moving phase we discuss how there can be a transition from a liquid-like state to dynamically ordered moving crystal, smectic, or nematic states. Systems with periodic or quasiperiodic substrates can have multiple nonequilibrium second or first order transitions in the moving state between chaotic and coherent phases, and can exhibit hysteresis. We also discuss systems with competing repulsive and attractive interactions, which undergo dynamical transitions into stripes and other complex morphologies when driven over random substrates. Throughout this work we highlight open issues and future directions such as absorbing phase transitions, nonequilibrium work relations, inertia, the role of non-dissipative dynamics such as Magnus effects, and how these results could be extended to the broader issues of plasticity in crystals, amorphous solids, and jamming phenomena.
{"title":"Depinning and nonequilibrium dynamic phases of particle assemblies driven over random and ordered substrates: a review","authors":"C. Reichhardt, C. Reichhardt","doi":"10.1088/1361-6633/80/2/026501","DOIUrl":"https://doi.org/10.1088/1361-6633/80/2/026501","url":null,"abstract":"We review the depinning and nonequilibrium phases of collectively interacting particle systems driven over random or periodic substrates. This type of system is relevant to vortices in type-II superconductors, sliding charge density waves, electron crystals, colloids, stripe and pattern forming systems, and skyrmions, and could also have connections to jamming, glassy behaviors, and active matter. These systems are also ideal for exploring the broader issues of characterizing transient and steady state nonequilibrium flow phases as well as nonequilibrium phase transitions between distinct dynamical phases, analogous to phase transitions between different equilibrium states. We discuss the differences between elastic and plastic depinning on random substrates and the different types of nonequilibrium phases which are associated with specific features in the velocity-force curves, fluctuation spectra, scaling relations, and local or global particle ordering. We describe how these quantities can change depending on the dimension, anisotropy, disorder strength, and the presence of hysteresis. Within the moving phase we discuss how there can be a transition from a liquid-like state to dynamically ordered moving crystal, smectic, or nematic states. Systems with periodic or quasiperiodic substrates can have multiple nonequilibrium second or first order transitions in the moving state between chaotic and coherent phases, and can exhibit hysteresis. We also discuss systems with competing repulsive and attractive interactions, which undergo dynamical transitions into stripes and other complex morphologies when driven over random substrates. Throughout this work we highlight open issues and future directions such as absorbing phase transitions, nonequilibrium work relations, inertia, the role of non-dissipative dynamics such as Magnus effects, and how these results could be extended to the broader issues of plasticity in crystals, amorphous solids, and jamming phenomena.","PeriodicalId":21110,"journal":{"name":"Reports on Progress in Physics","volume":null,"pages":null},"PeriodicalIF":18.1,"publicationDate":"2016-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76884099","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}
Pub Date : 2016-02-10DOI: 10.1088/0034-4885/79/3/032601
P. Hoffmann
Molecular motors are the workhorses of living cells. Seemingly by ‘magic’, these molecules are able to complete purposeful tasks while being immersed in a sea of thermal chaos. Here, we review the current understanding of how these machines work, present simple models based on thermal ratchets, discuss implications for statistical physics, and provide an overview of ongoing research in this important and fascinating field of study.
{"title":"How molecular motors extract order from chaos (a key issues review)","authors":"P. Hoffmann","doi":"10.1088/0034-4885/79/3/032601","DOIUrl":"https://doi.org/10.1088/0034-4885/79/3/032601","url":null,"abstract":"Molecular motors are the workhorses of living cells. Seemingly by ‘magic’, these molecules are able to complete purposeful tasks while being immersed in a sea of thermal chaos. Here, we review the current understanding of how these machines work, present simple models based on thermal ratchets, discuss implications for statistical physics, and provide an overview of ongoing research in this important and fascinating field of study.","PeriodicalId":21110,"journal":{"name":"Reports on Progress in Physics","volume":null,"pages":null},"PeriodicalIF":18.1,"publicationDate":"2016-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80441402","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}
Pub Date : 2016-02-10DOI: 10.1088/0034-4885/79/3/036901
W. Borucki
The Kepler Mission is a space observatory launched in 2009 by NASA to monitor 170 000 stars over a period of four years to determine the frequency of Earth-size and larger planets in and near the habitable zone of Sun-like stars, the size and orbital distributions of these planets, and the types of stars they orbit. Kepler is the tenth in the series of NASA Discovery Program missions that are competitively-selected, PI-directed, medium-cost missions. The Mission concept and various instrument prototypes were developed at the Ames Research Center over a period of 18 years starting in 1983. The development of techniques to do the 10 ppm photometry required for Mission success took years of experimentation, several workshops, and the exploration of many ‘blind alleys’ before the construction of the flight instrument. Beginning in 1992 at the start of the NASA Discovery Program, the Kepler Mission concept was proposed five times before its acceptance for mission development in 2001. During that period, the concept evolved from a photometer in an L2 orbit that monitored 6000 stars in a 50 sq deg field-of-view (FOV) to one that was in a heliocentric orbit that simultaneously monitored 170 000 stars with a 105 sq deg FOV. Analysis of the data to date has detected over 4600 planetary candidates which include several hundred Earth-size planetary candidates, over a thousand confirmed planets, and Earth-size planets in the habitable zone (HZ). These discoveries provide the information required for estimates of the frequency of planets in our galaxy. The Mission results show that most stars have planets, many of these planets are similar in size to the Earth, and that systems with several planets are common. Although planets in the HZ are common, many are substantially larger than Earth.
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Pub Date : 2016-02-10DOI: 10.1088/0034-4885/79/3/036401
C. B. de Araújo, A. Gomes, G. Boudebs
Various techniques to characterize the nonlinear (NL) optical response of centro-symmetric materials are presented and evaluated with emphasis on the relationship between the macroscopic measurable quantities and the microscopic properties of photonic materials. NL refraction and NL absorption of the materials are the phenomena of major interest. The dependence of the NL refraction and NL absorption coefficients on the nature of the materials was studied as well as on the laser excitation characteristics of wavelength, intensity, spatial profile, pulse duration and pulses repetition rate. Selected experimental results are discussed and illustrated. The various techniques currently available were compared and their relative advantages and drawbacks were evaluated. Critical comparisons among established techniques provided elements to evaluate their accuracies and sensitivities with respect to novel methods that present improvements with respect to the conventional techniques.
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