Analytical pair correlations in ideal quantum gases: Temperature-dependent bunching and antibunching

The fluctuation-dissipation theorem together with the exact density response spectrum for ideal quantum gases has been utilized to yield a new expression for the static structure factor, which we use to derive exact analytical expressions for the temperature{dependent pair distribution function g(r) of the ideal gases. The plots of bosonic and fermionic g(r) display "Bose pile" and "Fermi hole" typically akin to bunching and antibunching as observed experimentally for ultracold atomic gases. The behavior of spin-scaled pair correlation for fermions is almost featureless but bosons show a rich structure including long-range correlations near T_c. The coherent state at T=0 shows no correlation at all, just like single-mode lasers. The depicted decreasing trend in correlation with decrease in temperature for T < T_c should be observable in accurate experiments.Comment: 8 pages, 1 figure, minor revisio

HOW TO TALK TO AN ANGRY CUSTOMER

In the work presented the potential of a pyrometric process control during laser beam soldering will be enhanced. Primarily we have developed a processing head with an integrated up-to-date pyrometric sensor conditioned for the temperature range of soft soldering. Using high speed photography we have analysed the detected secondary emissions during laser beam soldering and correlated the acquired pyrometric signals of process emissions with processes sequencing. Finally we named different strategies and control methods to achieve reliable high quality solder joints implementing a pyrometric process control

Comparing the Structural Components Variance Estimator and U-Statistics Variance Estimator When Assessing the Difference Between Correlated AUCs with Finite Samples

Introduction: The structural components variance estimator proposed by DeLong et al. (1988) is a popular approach used when comparing two correlated AUCs. However, this variance estimator is biased and could be problematic with small sample sizes. Methods: A U-statistics based variance estimator approach is presented and compared with the structural components variance estimator through a large-scale simulation study under different finite-sample size configurations. Results: The U-statistics variance estimator was unbiased for the true variance of the difference between correlated AUCs regardless of the sample size and had lower RMSE than the structural components variance estimator, providing better type 1 error control and larger power. The structural components variance estimator provided increasingly biased variance estimates as the correlation between biomarkers increased. Discussion: When comparing two correlated AUCs, it is recommended that the U-Statistics variance estimator be used whenever possible, especially for finite sample sizes and highly correlated biomarkers

Nanomechanical morphology of amorphous, transition, and crystalline domains in phase change memory thin films

In the search for phase change materials (PCM) that may rival traditional random access memory, a complete understanding of the amorphous to crystalline phase transition is required. For the well-known Ge2Sb2Te5 (GST) and GeTe (GT) chalcogenides, which display nucleation and growth dominated crystallization kinetics, respectively, this work explores the nanomechanical morphology of amorphous and crystalline phases in 50 nm thin films. Subjecting these PCM specimens to a lateral thermal gradient spanning the crystallization temperature allows for a detailed morphological investigation. Surface and depth-dependent analyses of the resulting amorphous, transition and crystalline regions are achieved with shallow angle cross-sections, uniquely implemented with beam exit Ar ion polishing. To resolve the distinct phases, ultrasonic force microscopy (UFM) with simultaneous topography is implemented revealing a relative stiffness contrast between the amorphous and crystalline phases of 14% for the free film surface and 20% for the cross-sectioned surface. Nucleation is observed to occur preferentially at the PCM-substrate and free film interface for both GST and GT, while fine subsurface structures are found to be sputtering direction dependent. Combining surface and cross-section nanomechanical mapping in this manner allows 3D analysis of microstructure and defects with nanoscale lateral and depth resolution, applicable to a wide range of materials characterization studies where the detection of subtle variations in elastic modulus or stiffness are required

Проектирование станка с ЧПУ для маркировки деталей лазером

The increasing demands in MEMS fabrication in the past led to new requirements in production technology for these devices. Especially the packaging and assembly of optical devices like high power diode lasers require high accuracy in positioning and high reproducibility in combination with low production costs. Conventional assembly technology and mechanical adjustment methods are time consuming and expensive. Therefore a need of new assembly procedures arose. Each component of the system has to be positioned and fixed. The equipment for manipulating is very expensive. Also adjustment of the parts after joining requires additional mechanical devices that need to be accessible after joining. The decreasing dimensions of the microsystems cause problems in assembly and increase dramatically the tolerance conditions The laser beam micro forming as a non-contact tool offers the possibility of active adjustment after the assembly is completed. This paper describes this new technology pointing out the used mechanisms of laser induces deformation: From the basic mechanisms dedicated structures are derived to achieve the desired degrees of freedom for the adjustment process. Based on the upsetting mechanism the positioning of a cylindrical lens in front of a high power diode laser is shown. The adjustment in two degrees of freedom can be realized by irradiating the actuating structure from one direction. The achieved accuracy is in the micron range. The knowledge transfer to a tube-like actuator will be demonstrated. The tilting of a mirror in two rotational movements will be shown. The results to be presented have partially been achieved within the Collaborative Research Center (SFB) 440 "Assembly of Hybrid Microsystems" which was financially supported by the Deutsche Forschungsgemeinschaft DFG

Topological Correlations in a Layer Adsorbed on a Crystal Surface

The incoherent scattering of electrons by a layer adsorbed at a single crystal surface is determined by the topological correlations of elements forming the adsorbed layer. The model for the description of atoms or molecules adsorbed on the surface is formulated in terms of occupation operators which are expressed in terms of pseudospin operators with a given spin value. The correlations can be determined by the fluctuation dissipation theorem in connection with the susceptibility or given directly by means of the Green functions properly chosen. An example of the topological or chemical disorder of two components is considered in detail. The calculations of the topological correlations allow us to find the incoherent scattering amplitude as a function of the surface coverage which can be experimentally detected.Zadanie pt. „Digitalizacja i udostępnienie w Cyfrowym Repozytorium Uniwersytetu Łódzkiego kolekcji czasopism naukowych wydawanych przez Uniwersytet Łódzki” nr 885/P-DUN/2014 zostało dofinansowane ze środków MNiSW w ramach działalności upowszechniającej naukę

Justice Kennedy and the Environment: Property, States\u27 Rights, and a Persistent Search for Nexus

Justice Anthony Kennedy, now clearly the pivot of the Roberts Court, is the Court\u27s crucial voice in environmental law cases. Kennedy\u27s central role was never more evident than in the two most celebrated environmental cases of the last few years, Kelo v. City of New London and Rapanos v. United States, as he supplied the critical vote in both. Kennedy has in fact been the needle of the Supreme Court\u27s environmental law compass since his nomination in 1988. Although he wrote surprisingly few environmental law opinions over his first eighteen years on the Court, Kennedy was in the majority an astonishing ninety-six percent of the time (as compared to his generic record of being in the majority slightly over sixty percent of the time). This article examines Kennedy\u27s environmental law record on the Court, as well as his preceding thirteen years on the Ninth Circuit. The article evaluates all of the environmental law cases in which he wrote an opinion over those three decades and catalogues his voting record in all Supreme Court cases in which he participated. One striking measure of Kennedy\u27s influence is that he has written just one environmental dissent while on the Court, and that was on states\u27 rights grounds, one of his chief priorities. We believe that Kennedy is considerably more interested in allowing trial judges to resolve cases on the basis of context than in establishing broadly-applicable doctrine. That is, he is a doctrinal minimalist. By consistently demanding a demonstrated nexus between doctrine and facts, he has shown an intolerance for elevating abstract philosophy over concrete justice. And, despite his unassailable devotion to states\u27 rights, Kennedy has been quite willing to find federal preemption when it serves deregulation purposes. On the other hand, he is far from an anti-regulatory zealot, although he prefers only one level of governmental regulation. At what might be close to the mid-point in his Court career-and with his power perhaps at its zenith-Justice Kennedy is clearly not someone any litigant can ignore. We hope this article gives both environmental litigants and academics a fertile resource to till. Although Kennedy\u27s environmental record has been sparse until lately, he may be receptive to environmental claims if they are factually well-grounded and do not conflict with his overriding concern for states\u27 rights. The article concludes with some comparisons between Kennedy and Justice Oliver Wendell Holmes

The Second Glass Ceiling Impedes Women Entrepreneurs

The glass ceiling phenomenon that impedes the advancement of talented women professionals into senior executive roles inside large corporations is widely recognized in society, studied in the management literature, taught in business schools, and tangibly felt by many women executives. Outside the corporate setting, we show that a second glass ceiling exists for women entrepreneurs and women small business owners. This second glass ceiling is a gender bias that obstructs women-owned small firms from accessing the financial capital required to start new firms and fuel the growth of existing firms. This paper (1) defines the second glass ceiling phenomenon, (2) provides evidence of its existence, causes and effects, and (3) proposes what both women entrepreneurs and financial capital managers should do to mitigate its deleterious effects

Carbon Fixation Trends in Eleven of the World’s Largest Lakes: 2003–2018

Large freshwater lakes provide immense value to the surrounding populations, yet there is limited understanding of how these lakes will respond to climate change and other factors. This study uses satellite remote sensing to estimate annual, lake-wide primary production in 11 of the world’s largest lakes from 2003–2018. These lakes include the five Laurentian Great Lakes, the three African Great Lakes, Lake Baikal, and Great Bear and Great Slave Lakes. Mean annual production in these lakes ranged from under 200 mgC/m2/day to over 1100 mgC/m2/day, and the lakes were placed into one of three distinct groups (oligotrophic, mesotrophic, or eutrophic) based on their level of production. The analysis revealed only three lakes with significant production trends over the study period, with increases in Great Bear Lake (24% increase over the study period) and Great Slave Lake (27%) and a decline in Lake Tanganyika (−16%). These changes appear to be related to climate change, including increasing temperatures and solar radiation and decreasing wind speeds. This study is the first to use consistent methodology to study primary production in the world’s largest lakes, allowing for these novel between-lake comparisons and assessment of inter-annual trends