THE IMPACT OF SELECTED HEDGING STRATEGIES ON THE CASH FLOW POSITION OF CATTLE FEEDERS

Agricultural Finance,

A spatially and temporally localized sub-laser-cycle electron source

We present an experimental and numerical study of electron emission from a sharp tungsten tip triggered by sub-8 femtosecond low power laser pulses. This process is non-linear in the laser electric field, and the non-linearity can be tuned via the DC voltage applied to the tip. Numerical simulations of this system show that electron emission takes place within less than one optical period of the exciting laser pulse, so that an 8 fsec 800 nm laser pulse is capable of producing a single electron pulse of less than 1 fsec duration. Furthermore, we find that the carrier-envelope phase dependence of the emission process is smaller than 0.1% for an 8 fsec pulse but is steeply increasing with decreasing laser pulse duration.Comment: 4 pages, 5 figure

Sports review: A content analysis of the International Review for the Sociology of Sport, the Journal of Sport and Social Issues and the Sociology of Sport Journal across 25 years

The International Review for the Sociology of Sport, the Journal of Sport and Social Issues and Sociology of Sport Journal have individually and collectively been subject to a systematic content analysis. By focusing on substantive research papers published in these three journals over a 25-year time period it is possible to identify the topics that have featured within the sociology of sport. The purpose of the study was to identify the dominant themes, sports, countries, methodological frameworks and theoretical perspectives that have appeared in the research papers published in these three journals. Using the terms, identified by the author(s), that appear in the paper’s title, abstract and/or listed as a key word, subject term or geographical term, a baseline is established to reflect on the development of the sub-discipline as represented by the content of these three journals. It is suggested that the findings illustrate what many of the more experienced practitioners in the field may have felt subjectively. On the basis of this systematic, empirical study it is now possible to identify those areas have received extensive coverage and those which are under-researched within the sociology of sport. The findings are used to inform a discussion of the role of academic journals and the recent contributions made by Michael Silk, David Andrews, Michael Atkinson and Dominic Malcolm on the past, present and future of the ‘sociology of sport’

Canonical Models of Dielectric Response

The interaction of electromagnetic fields with a solid is characterized by several interconnected response functions: the dielectric function ε(ω), index of refraction N(ω), conductivity σ(ω), and optical impedance Z(ω). Here we utilize three canonical models of dielectric response -- the damped harmonic oscillator, Debye polarization response, and the Drude model -- to discuss these four optical response functions. Special emphasis is devoted to the response of a Drude metal. Our main focus is on electromagnetic wave propagation through a material. We also discuss the relaxation of charge fluctuations within the context of the three canonical models of response

Classical Fano Oscillator

Starting from the quantum-mechanical Fano-Anderson Hamiltonian, we derive classical equations of motion for coordinates associated with the discrete and continuum states. The frequency-dependent absorption spectrum associated with this classical system exhibits the same Fano line shape as the quantum-mechanical system when appropriate correspondences between classical and quantum variables are made. In the time domain, the response of this classical Fano oscillator depends upon the asymmetry parameter q that appears in the expression for the Fano line shape. In particular, under the influence of impulsive driving of the system, the discrete oscillator\u27s phase changes by ±π/2 as q increases from zero (maximum asymmetry in the frequency domain) to ∓∞ (minimum asymmetry). Previously published ultrafast-laser-pulse-driven coherent-phonon oscillations in degenerate p-type Si [ K. Kato et al. Jpn. J. Appl. Phys. 48 100205 (2009)] are discussed in light of these theoretical results

Temperature Dependence of Silicon Carrier Effective Masses with Application to FemtosecondReflectivity Measurements

The conductivity effective masses of electrons and holes in Si are calculated for carrier temperatures from 1 to 3000 K. The temperature dependence of the electron mass is calculated by use of a phenomenological model of conduction-band nonparabolicity that has been fitted to experimental measurements of the dependence of the electron conductivity effective mass on carrier concentration. The hole mass is investigated by tight-binding calculations of the valence bands, which have been adjusted to match experimental values of the valence-band curvature parameters at the top of the valence band. The calculations are in excellent agreement with femtosecond-laser reflectivity measurements of the change in optical effective mass as hot carriers cool from 1550 to 300 K

‘Together … for only a moment’ British newspaper constructions of altruistic non-commercial surrogate motherhood

Objectives: To explore how national altruistic surrogacy is framed in a representative selection of the British press. Methods: A study of 90 British national newspaper articles was carried out using the Lexis-Nexis data base to search for articles on altruistic surrogacy. Content analysis of gain, loss, neutral frames and high or low alarm and vulnerability frames in the titles and the body of the text was carried out. The type of construction used in the article content was also analysed. Data were coded and consensus reached using a coding strategy specifically developed for the purposes of this study. Results: Titles and content were predominantly loss, high alarm and high vulnerability framed. The content was also gain framed, and written with a focus on the social and legal aspects differentially between the newspaper types. Discussion: The tabloid press emphasizes social issues, and the middle market and serious press focus on legal issues of altruistic surrogacy. Selectively framed and reinforced information provided by the different newspapers, reflect the different readership, with Tabloid readers likely to be, surrogates (mostly from lower socioeconomic strata) and serious/ middle-market readers likely to be commissioning parents (mostly professionals)

Alkali-metal vibrations in bcc, fcc, hcp, and 9R structures: Implications for the energetics of Li and Na martensitic phases

We present an embedded-atom-method (EAM) model that is specifically designed to accurately describe vibrations in bcc alkali metals. Using this model, we study bulk vibrational structure of Li, Na, K, and Rb when configured in bcc and the closed-packed (cp) fcc, hcp, and 9$R$ phases. From the vibrational density of states for each phase we thence find the corresponding vibrational contribution $A_{\rm vib}(T)$ to the Helmholtz free energy $A(T)$. Utilizing (i) differences in $A_{\rm vib}(T)$ between the bcc and cp structures and (ii) experimentally inferred thermodynamic transition temperatures for Li and Na (which martensitically transform from bcc to cp phases upon cooling), we extract values for zero-temperature energy differences between the bcc and relevant cp phases. We also put constraints on zero-temperature cp-bcc energy differences for K and Rb, which do not exhibit temperature induced transitions.Comment: 14 pages, 9 figure