20,969 research outputs found
Contributions of Vacuum and Plasmon Modes to the Force on a Small Sphere near a Plate
The force on a small sphere with a plasma model dielectric function and in
the presence of a perfectly reflecting plane is considered. The contribution of
both the vacuum modes of the quantized electromagnetic field and of plasmon
modes in the sphere are discussed. In the case that the plasmon modes are in
their ground state, quasi-oscillatory terms from the vacuum and plasmon parts
cancel one another, leading a monotonic attractive force. If the plasmon modes
are not in the ground state, the net force is quasi-oscillatory. In both cases,
the sphere behaves in the same way as does an atom in either its ground state
or an excited state.Comment: 7 pages, no figures, talk presented at "Quantum Fields under External
Conditions - 2005", Barcelona, Spain, September 200
The Casimir effect for thin plasma sheets and the role of the surface plasmons
We consider the Casimir force betweeen two dielectric bodies described by the
plasma model and between two infinitely thin plasma sheets. In both cases in
addition to the photon modes surface plasmons are present in the spectrum of
the electromagnetic field. We investigate the contribution of both types of
modes to the Casimir force and confirm resp. find in both models large
compensations between the plasmon modes themselves and between them and the
photon modes especially at large distances. Our conclusion is that the
separation of the vacuum energy into plasmon and photon contributions must be
handled with care except for the case of small separations.Comment: submitted to JPhysA Special Issue QFEXT'05, replaced due to a wrong
Latex comman
Reducing Reoffending: Review of Selected Countries: Final Review for Audit Scotland
The report reviews reoffending patterns in Scotland, England and Wales, Ireland, Northern Ireland, Norway and New Zealand to establish relevant conditions for different rates of reoffending. A significant part of the report, however, is given over to a critical examination of the concept of 'reoffending' itself which is more a measure of criminal justice agency behaviour than individual behaviour. The report concludes with some suggestions for moving beyond such thin, technocratic understanding of reoffending and rehabilitation. This work was commissioned by and submitted to Audit Scotland
Diffraction in time: An exactly solvable model
In recent years, matter-wave interferometry has attracted growing attention due to its unique suitability for high-precision measurements and the study of fundamental aspects of quantum theory. Diffraction and interference of matter waves can be observed not only at a spatial aperture (such as a screen edge, slit, or grating), but also at a time-domain aperture (such as an absorbing barrier, or “shutter,” that is being periodically switched on and off). The wave phenomenon of the latter type is commonly referred to as “diffraction in time.” Here, we introduce a versatile, exactly solvable model of diffraction in time. It describes time evolution of an arbitrary initial quantum state in the presence of a time-dependent absorbing barrier, governed by an arbitrary aperture function. Our results enable a quantitative description of diffraction and interference patterns in a large variety of setups, and may be used to devise new diffraction and interference experiments with atoms and molecules
FCStone Conversion to a Public Corporation
FCStone Group (FCS) is a publicly held corporation that converted from a cooperative to a private corporation in 2005, and then converted to a public corporation in 2007. It is an integrated commodity risk management company that provides risk management consulting and transaction execution services to commercial commodity intermediaries, end users, and producers. This case study focuses primarily on the period from the first conversion in 2005 to six months after the public offering in March 2007. Because the financial benefits received by each of the cooperative owners of FCS are dependent on the timing of their sale of FCS stock, stock price information and benefit estimates are provided up to early November 2008.Agribusiness,
Fluctuations of the Casimir-Polder force between an atom and a conducting wall
We consider the quantum fluctuations of the Casimir-Polder force between a
neutral atom and a perfectly conducting wall in the ground state of the system.
In order to obtain the atom-wall force fluctuation we first define an operator
directly associated to the force experienced by the atom considered as a
polarizable body in an electromagnetic field, and we use a time-averaged force
operator in order to avoid ultraviolet divergences appearing in the fluctuation
of the force. This time-averaged force operator takes into account that any
measurement involves a finite time. We also calculate the Casimir-Polder force
fluctuation for an atom between two conducting walls. Experimental
observability of these Casimir-Polder force fluctuations is also discussed, as
well as the dependence of the relative force fluctuation on the duration of the
measurement.Comment: 6 page
A Comparison of Traditional and Newly Emerging Forms of Cooperative Capitalization
This paper compares the traditional forms of capitalization used by American co-ops to newly emerging forms. It is based on an in-depth review of several case co-ops. A broad framework is provided that may be beneficial in more extensive studies of capitalization practices of cooperatives and similar organizations. It is divided into three parts. Part One outlines the alternative capitalization forms being used by cooperatives and their antecedents, where conversions to other structures and forms have occurred. Two basic capitalization forms have been used by cooperatives: traditional (open) and new generation (closed). Cooperatives using both forms have elected to add new capitalization features, such as use of publicly listed stock, or have elected to convert to different forms, such as an LLC or a C corporation. Several perceived advantages have motivated these changes besides the traditional advantages utilized by cooperative corporations, limited liability and single taxation. They include access to capital, liquidity and appreciability of stock. Part Two provides a brief description of the nature and experience of several modern cooperative organizations using the framework presented in Part One. The descriptions are based on in-depth case studies. The case study selections are from a broad cross-section of cooperatives that include the following: (1) Mid-Kansas Cooperative (traditional, centralized, local grain marketing and farm supply using only internally generated equity); (2) Land O'Lakes (traditional, centralized and federated, regional dairy marketing and processing and farm supply using only internally generated equity and registered debt financing); (3) CHS Cooperatives (traditional, primarily federated, regional grain marketing and processing and farm supply, with the recent addition of publicly listed preferred stock); and (4) U.S. Premium Beef (new generation, centralized, regional beef processing using closely held but tradeable common stock and proposal to convert to an LLC with member and non-member tradeable stock). In addition brief mention is made of other cooperatives including (5) Dakota Growers Pasta (new generation, centralized, regional durum wheat processing with recent conversion to C corporation); (6) South Dakota Soybean Processing (new generation, centralized regional soybean processing with conversion to LLC); (7) Pro-Fac and Birds Eye Foods (new generation centralized regional frozen vegetable processing with publicly listed stock and transition of processing entity, Birds Eye, to majority ownership by investor-oriented partner likely to exit through an IPO) and (8) Gold Kist (traditional, centralized regional poultry processing with proposed conversion to publicly traded C corporation). Part Three will briefly outline some of the challenges facing cooperatives in the future with reference to capitalization.Financial Economics, Agribusiness,
The great outdoors: how a green exercise environment can benefit all
The studies of human and environment interactions usually consider the extremes of environment on individuals or how humans affect the environment. It is well known that physical activity improves both physiological and psychological well-being, but further evidence is required to ascertain how different environments influence and shape health. This review considers the declining levels of physical activity, particularly in the Western world, and how the environment may help motivate and facilitate physical activity. It also addresses the additional physiological and mental health benefits that appear to occur when exercise is performed in an outdoor environment. However, people's connectedness to nature appears to be changing and this has important implications as to how humans are now interacting with nature. Barriers exist, and it is important that these are considered when discussing how to make exercise in the outdoors accessible and beneficial for all. The synergistic combination of exercise and exposure to nature and thus the 'great outdoors' could be used as a powerful tool to help fight the growing incidence of both physical inactivity and non-communicable disease. © 2013 Gladwell et al.; licensee BioMed Central Ltd
Transfer of molybdenum disulfide to various metals
Sliding friction experiments were conducted with molybdenum disulfide single crystals in contact with sputter cleaned surfaces of copper, nickel, gold, and 304 stainless steel. Transfer of the molybdenum disulfide to the metals was monitored with Auger electron spectroscopy. Results of the investigation indicate molybdenum disulfide transfers to all clean metal surfaces after a single pass over the metal surface with film thickness observed to increase with repeated passes over the same surfaces. Large particle transfer occurs when the orientation of the crystallites is other than basal. This is frequently accompanied by abrasion of the metal. Adhesion of molybdenum disulfide films occurred readily to copper and nickel, less readily to 304 stainless steel, and even less effectively to the gold, which indicates a chemical effect
DNA sensing by electrocatalysis with hemoglobin
Electrocatalysis offers a means of electrochemical signal amplification, yet in DNA-based sensors, electrocatalysis has required high-density DNA films and strict assembly and passivation conditions. Here, we describe the use of hemoglobin as a robust and effective electron sink for electrocatalysis in DNA sensing on low-density DNA films. Protein shielding of the heme redox center minimizes direct reduction at the electrode surface and permits assays on low-density DNA films. Electrocatalysis with methylene blue that is covalently tethered to the DNA by a flexible alkyl chain linkage allows for efficient interactions with both the base stack and hemoglobin. Consistent suppression of the redox signal upon incorporation of a single cytosine-adenine (CA) mismatch in the DNA oligomer demonstrates that both the unamplified and the electrocatalytically amplified redox signals are generated through DNA-mediated charge transport. Electrocatalysis with hemoglobin is robust: It is stable to pH and temperature variations. The utility and applicability of electrocatalysis with hemoglobin is demonstrated through restriction enzyme detection, and an enhancement in sensitivity permits femtomole DNA sampling
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