Frequency, intensity, and field fluctuations in laser oscillators

The basic differential equation governing laser noise is derived from classical and quantum mechanical considerations. Its linearized Van Der Pol form is used to derive the frequency, field, and intensity fluctuation spectra

Aerial Mineral and Organic Particulate Deposition in East Texas

This study determined the monthly amount, particle size distribution, and chemical composition of particulate deposition in East Texas over a one-year period. It also recognized the seasonal patterns of this deposition as well as its primary origins as either mineral or organic particulate deposition. The study recorded the monthly mass of deposition, particle size distribution, and the chemical makeup of deposition throughout a period of twelve months at seven sampling locations. SEM-EDS technology was used in conjunction with PCI programming to measure the sizes of depositional particles throughout this time period and identify their chemical composition. The total yearly deposition recorded in this study was 22.9865 kg/ha. Of this yearly deposition, 8.5582 kg/ha was Si deposition, 2.2923 kg/ha was C deposition, 1.4394 kg/ha was Ba deposition, 1.4679 kg/ha was Na deposition, 1.4679 kg/ha was Al deposition, 0.3146 kg/ha was Ca deposition, 0.7846 kg/ha was K deposition, and 1.4679 kg/ha was Fe deposition. Si deposition had a monthly range of 0.1939 kg/ha – 1.5393 kg/ha, C deposition had a monthly range of 0.0262 kg/ha – 0.6871 kg/ha, Ba had a monthly range of 0.0380 kg/ha – 0.2984 kg/ha, Na had a monthly range of 0.0330 kg/ha – 0.3619 kg/ha, Al had a monthly range of 0.0330 kg/ha – 0.3619 kg/ha, Ca had a monthly range of 0.0022 kg/ha – 0.0958 kg/ha, K had a monthly range of 0.0190 kg/ha – 0.1714 kg/ha, and Fe had a monthly range of 0.0330 kg/ha – 0.3619 kg/ha. Mean particle size increased from January 2019-April 2019. Particle size increased during high pollen months. Elements found in soils tended to make up a larger percentage of the deposition during drier months

Characterizing and testing a thermally isolating superconducting link for SAFIRE-like missions

The recent discovery of high temperature ceramic superconductors with transition temperatures above 90 K has opened the possibilities for new space applications. One application is the fabrication of an electrically conducting and thermally isolating electronic link to connect IR detectors to data acquisition electronics on remote sensing platforms. The Spectroscopy of the Atmosphere using Far Infra-Red Emission (SAFIRE) mission is an example of a platform which employs hybrid dewars and combines both mechanical and cryogenic liquid cooling. This new technology is limited by the heat conducted through sensor array leads that connect the electronics (at approximately 80 K) to the sensors (at approximately 4 K). This link must be made of material that has high electrical conductivity and high thermal resistance. The YBa2Cu3O(x) superconductor with a transition temperature, T(sub c), of 93 K can achieve these conflicting requirements. A link with these characteristics will improve the thermal isolation of IR detectors and will increase the lifetime of the cryogen. A reduction of the thermal load due to the link by a factor of four will increase the lifetime of a seven year mission by about one year

General practice registrars’ intentions for future practice: Implications for rural medical workforce planning

The models of practice that general practice registrars (GPRs) envisage undertaking will affect workforce supply. The aim of this research was to determine practice intentions of current GPRs in a regional general practice training program (Coast City Country General Practice Training). Questionnaires were circulated to 220 GPRs undertaking general practice placements to determine characteristics of ideal practice models and intentions for future practice. Responses were received for 99 participants (45%). Current GPRs intend to work an average of less than eight half-day sessions/week, with male participants intending to work more hours (t(91) = 3.528, P = 0.001). More than one-third of this regional cohort intends to practice in metropolitan centres. Proximity to family and friends was the most important factor influencing the choice of practice location. Men ranked remuneration for work as more important (t (88) = –4.280, P \u3c 0.001) and women ranked the ability to work part-time higher (t(94) = 3.697, P \u3c 0.001). Fee-for-service payment alone, or in combination with capitation, was the preferred payment system. Only 22% of Australian medical graduates intend to own their own practice compared with 52% of international medical graduates (χ2(1) = 8.498, P = 0.004). Future general practitioners (GPs) intend to work fewer hours than current GPs. Assumptions about lifestyle factors, practice models and possible professional roles should be carefully evaluated when developing strategies to recruit GPs and GPRs into rural practice

Predicting Axonal Response to Molecular Gradients with a Computational Model of Filopodial Dynamics

Axons are often guided to their targets in the developing nervous system by attractive or repulsive molecular concentration gradients. We propose a computational model for gradient sensing and directed movement of the growth cone mediated by filopodia. We show that relatively simple mechanisms are sufficient to generate realistic rajectories for both the short-term response of axons to steep gradients and the long-term response of axons to shallow gradients. The model makes testable predictions for axonal response to attractive and repulsive gradients of different concentrations and steepness, the size of the intracellular amplification of the gradient signal, and the differences in intracellular signaling required for repulsive versus attractive turning

A comparison of superconductor and manganin technology for electronic links used in space mission applications

The electronic link connecting cryogenically cooled radiation detectors to data acquisition and signal processing electronics at higher temperatures contributes significantly to the total heat load on spacecraft cooling systems that use combined mechanical and cryogenic liquid cooling. Using high transition temperature superconductors for this link has been proposed to increase the lifetime of space missions. Herein, several YBCO (YBa2Cu3O7) superconductor-substrate combinations were examined and total heat loads were compared to manganin wire technology in current use. Using numerical solutions to the heat-flow equations, it is shown that replacing manganin technology with YBCO thick film technology can extend a 7-year mission by up to 1 year

The post-2009 influenza pandemic era : time to revisit antibody immunodominance

The current inactivated influenza vaccines rely on the induction of neutralizing antibodies against the head domain of the viral hemagglutinin (HA). The HA head contains five immunodominant antigenic sites, all of which are subject to antigenic drift, thereby limiting vaccine efficacy. Bypassing the immune system's tendency to focus on the most variable regions of the HA may be a step toward more broadly protective influenza vaccines. However, this requires a better understanding of the biological meaning of immunodominance, and of the hierarchy between different antigenic sites. In this issue of the JCI, Liu et al. determined the immunodominance of the five antigenic sites of the HA head in experimentally infected mice, guinea pigs, and ferrets. All three species exhibited different preferences for the five sites of the 2009 pandemic H1N1 strain. Moreover, human subjects exhibited yet a different pattern of immunodominance following immunization with the standard inactivated influenza vaccine. Together, these results have important implications for influenza vaccine design and interpretation of animal models

What effect does short term Study Abroad (SA) have on learners’ vocabulary knowledge?

This thesis describes a study which tracks longitudinal changes in vocabularyknowledge during a short-term Study Abroad (SA) experience. A test ofproductive vocabulary knowledge, Lex30 (Meara & Fitzpatrick, 2000),requiring the production of word association responses, is used to elicit vocabulary from 38 Japanese L1 learners of English at four test times at equal intervals before and after an SA experience. The study starts by investigating whether there are changes in both the total number of words and in the number of less frequently occurring words produced by SA participants. Three additional ways of measuring the development of lexical knowledge over time are then proposed. The first examines changes in the ability of participants of different proficiency levels in producing collocates in response to Lex30 cue words. The second tracks changes in spelling accuracy to measure if improvements take place over time. The third analysis uses an online measuring instrument (Wmatrix; Rayson, 2009) to explore if there are any changes in the mastery of specific semantic domains. The results show that there is significant growth in the productive use of less frequent vocabulary knowledge during the SA period. There is also an increase in collocation production with lower proficiency participants and evidence of some improvement in the way certain vocabulary items are spelled. The tendency for SA learners to produce more words from semantic groups related to SA experiences is also demonstrated. Post-SA tests show that while some knowledge attrition occurs it does not decline to pre-SA levels. The studyshows how short-term SA programmes can be evaluated using a word association test, contributing to a better understanding of how vocabularydevelops during intensive language learning experiences. It also demonstrates the gradual shift of productive vocabulary knowledge from partial word knowledge to a more complete state of productive mastery

Book Review: Original Sin: Power, Technology and War in Outer Space

Author: Bleddyn E. Bowen Reviewed by Jeffrey Caton, colonel, US Air Force (retired), and president, Kepler Strategies LLC Based on three key arguments, Original Sin covers the development of spacepower during the Cold War, space technology’s progress, and the weapons, planning and doctrine that surround space warfare. The reviewer notes, “What sets Original Sin apart from similar books is the outstanding context it provides and its willingness to challenge trite slogans attached to spacepower.”https://press.armywarcollege.edu/parameters_bookshelf/1027/thumbnail.jp