Diffraction of sound by nearly rigid barriers

The diffraction of sound by barriers with surfaces of large, but finite, acoustic impedance was analyzed. Idealized source-barrier-receiver configurations in which the barriers may be considered as semi-infinite wedges are discussed. Particular attention is given to situations in which the source and receiver are at large distances from the tip of the wedge. The expression for the acoustic pressure in this limiting case is compared with the results of Pierce's analysis of diffraction by a rigid wedge. An expression for the insertion loss of a finite impedance barrier is compared with insertion loss formulas which are used extensively in selecting or designing barriers for noise control

Applications of acoustics in the measurement of coal slab thickness

The determination of the possibility of employing acoustic waves at ultrasonic frequencies for measurements of thicknesses of slabs of coal backed by shale is investigated. Fundamental information concerning the acoustical properties of coal, and the relationship between these properties and the structural and compositional parameters used to characterize coal samples was also sought. The testing device, which utilizes two matched transducers, is described

Fracture toughness of brittle materials determined with chevron notch specimens

The use of chevron-notch specimens for determining the plane strain fracture toughness (K sub Ic) of brittle materials is discussed. Three chevron-notch specimens were investigated: short bar, short rod, and four-point-bend. The dimensionless stress intensity coefficient used in computing K sub Ic is derived for the short bar specimen from the superposition of ligament-dependent and ligament-independent solutions for the straight through crack, and also from experimental compliance calibrations. Coefficients for the four-point-bend specimen were developed by the same superposition procedure, and with additional refinement using the slice model of Bluhm. Short rod specimen stress intensity coefficients were determined only by experimental compliance calibration. Performance of the three chevron-notch specimens and their stress intensity factor relations were evaluated by tests on hot-pressed silicon nitride and sintered aluminum oxide. Results obtained with the short bar and the four-point-bend specimens on silicon nitride are in good agreement and relatively free of specimen geometry and size effects within the range investigated. Results on aluminum oxide were affected by specimen size and chevron-notch geometry, believed due to a rising crack growth resistance curve for the material. Only the results for the short bar specimen are presented in detail

Sound propagation over uneven ground and irregular topography

The development of theoretical, computational, and experimental techniques for predicting the effects of irregular topography on long range sound propagation in the atmosphere is discussed. Irregular topography here is understood to imply a ground surface that (1) is not idealizable as being perfectly flat or (2) that is not idealizable as having a constant specific acoustic impedance. The study focuses on circumstances where the propagation is similar to what might be expected for noise from low-altitude air vehicles flying over suburban or rural terrain, such that rays from the source arrive at angles close to grazing incidence

Development of a post-fall multidisciplinary checklist to evaluate the in-patient fall

Background: Falls suffered by hospitalized patients are an important reportable event. Approximately 4 - 6 % of inpatient falls result in serious injury. Recurrent falls or delayed recognition of injury can harm patients and represents a medico-legal risk. In 2010, our tertiary-care academic medical center reviewed current practice regarding falls prevention and assessment to develop a comprehensive falls prevention program. The committee found that there was no consistent practice in the assessment by nurses or physicians of inpatients who had fallen, either for injury or for conditions which might have led to the fall. A new systematic checklist for evaluation of the hospital faller was developed by a team consisting of nursing, hospitalists, and a medical unit director. Purpose: To develop an evidence-based multi-disciplinary checklist to facilitate evaluation, implementation of secondary prevention interventions and documentation following a hospital fall. Description: The hospitalist and the general medical unit director reviewed relevant literature, consulted national experts, and drafted a multidisciplinary checklist, the UNMH Post-Fall/Huddle Tool, to be used by nurses and physicians in post-fall patient evaluation. The checklist was reviewed and revised with further input from key stakeholders including hospitalists, housestaff, and the adult Medical/Surgical Shared Governance Committee. It was implemented as part of a comprehensive falls prevention program 3 month pilot. The checklist prompts a three step process: (1) an initial 7-item assessment by nursing staff to determine factors which would necessitate immediate evaluation by cross-covering physicians versus deferring evaluation to the primary team; (2) a 5-item focused physical examination to be performed by a physician to assess the likelihood of injury and suggested diagnostic tests based on this examination; and (3) an interdisciplinary face-to-face meeting between the evaluating physician and nurse to review 7 specific possible precipitating events and implement potential interventions. The UNMH Post-Fall/Huddle Tool will be adapted into the electronic health record after pilot completion and evaluation. An educational presentation about falls and how to use the checklist was developed for residents and hospitalists. Use of the checklist was implemented in November, 2010. To date, nurses and residents report that the checklist is easy to use and that it facilitates a timely, multidisciplinary evaluation of patients who have fallen in the hospital. Conclusion: A multi-disciplinary post-fall checklist facilitates a consistent and evidence-based evaluation and treatment of patients who have fallen in the hospital

Propagation of aircraft noise

The major tasks undertaken were (1) analytical and laboratory experiments on the propagation of sound from sources near a flat surface of finite acoustic impedance; (2) laboratory experiments dealing with the reflection of sound from finite sized plane patches; and (3) the diffraction of sound by wedge-and trapezoidal-shape barriers. In addition, a series of measurements were made of the background noise levels for various jet flow conditions in the Anechoic Noise Facility of the Langley Research Center's Acoustic and Noise Reduction Laboratory

Junior faculty exchange program assists mid-career clinician-educators increase scholarly activity and meet promotion requirements

Project: Our institution requires peer-review scholarly products and an extramural reputation for promotion of clinician-educators to Associate Professor. Given a lack of robust research skill training during residency and a paucity of research mentors in our Division of Hospital Medicine, meeting these two promotion requirements has been especially challenging for many of our hospitalist faculty. We established a junior faculty exchange with other institutions in order to assist individual faculty members to gain a reputation outside of their home institutions, to develop external mentorship and career advice relationships with early career faculty, and to enhance networking and project collaborations. Methods: Participants were mid-career faculty who would gain the maximal career benefit from delivering an invited visit to an external institution and who have sufficient track record to deliver effective mentoring advice to early career hospitalists. Faculty at the late Assistant Professor level or recently promoted Associate Professors were selected by their Divisions leadership to spend one day at a hosting institution, deliver an invited grand rounds or similar didactic presentation, meet with senior leadership, and provide career advice to junior faculty. The program was reciprocal with one faculty member visiting an institution in exchange for that institution hosting a faculty member for a similar invited visit. Each institution covered the cost of travel and hotel accommodations. No honoraria were paid. Results: Over the first two years, four junior academic hospitalists were exchanged between three institutions. There was a high degree of satisfaction among surveyed visiting and visited junior faculty. Two on-going collaborative relationships and one jointly authored paper have resulted to date. Conclusion: A junior faculty exchange program assisted mid-career academic hospitalists establish extramural collaborations and meet promotion requirements that have been problematic at our institution. Implication: This relatively inexpensive faculty development program is easily adaptable by other institutions and may help generalist faculty increase scholarly activity, develop extra-institutional relationships, and achieve promotion.\u2

Structure-Based Design of Hepatitis C Virus Vaccines That Elicit Neutralizing Antibody Responses to a Conserved Epitope

Despite recent advances in therapeutic options, hepatitis C virus (HCV) remains a severe global disease burden, and a vaccine can substantially reduce its incidence. Due to its extremely high sequence variability, HCV can readily escape the immune response; thus, an effective vaccine must target conserved, functionally important epitopes. Using the structure of a broadly neutralizing antibody in complex with a conserved linear epitope from the HCV E2 envelope glycoprotein (residues 412 to 423; epitope I), we performed structure-based design of immunogens to induce antibody responses to this epitope. This resulted in epitope-based immunogens based on a cyclic defensin protein, as well as a bivalent immunogen with two copies of the epitope on the E2 surface. We solved the X-ray structure of a cyclic immunogen in complex with the HCV1 antibody and confirmed preservation of the epitope conformation and the HCV1 interface. Mice vaccinated with our designed immunogens produced robust antibody responses to epitope I, and their serum could neutralize HCV. Notably, the cyclic designs induced greater epitope-specific responses and neutralization than the native peptide epitope. Beyond successfully designing several novel HCV immunogens, this study demonstrates the principle that neutralizing anti-HCV antibodies can be induced by epitope-based, engineered vaccines and provides the basis for further efforts in structure-based design of HCV vaccines. IMPORTANCE: Hepatitis C virus is a leading cause of liver disease and liver cancer, with approximately 3% of the world\u27s population infected. To combat this virus, an effective vaccine would have distinct advantages over current therapeutic options, yet experimental vaccines have not been successful to date, due in part to the virus\u27s high sequence variability leading to immune escape. In this study, we rationally designed several vaccine immunogens based on the structure of a conserved epitope that is the target of broadly neutralizing antibodies. In vivo results in mice indicated that these antigens elicited epitope-specific neutralizing antibodies, with various degrees of potency and breadth. These promising results suggest that a rational design approach can be used to generate an effective vaccine for this virus

An empirical investigation of dance addiction

Although recreational dancing is associated with increased physical and psychological well-being, little is known about the harmful effects of excessive dancing. The aim of the present study was to explore the psychopathological factors associated with dance addiction. The sample comprised 447 salsa and ballroom dancers (68% female, mean age: 32.8 years) who danced recreationally at least once a week. The Exercise Addiction Inventory (Terry, Szabo, & Griffiths, 2004) was adapted for dance (Dance Addiction Inventory, DAI). Motivation, general mental health (BSI-GSI, and Mental Health Continuum), borderline personality disorder, eating disorder symptoms, and dance motives were also assessed. Five latent classes were explored based on addiction symptoms with 11% of participants belonging to the most problematic class. DAI was positively associated with psychiatric distress, borderline personality and eating disorder symptoms. Hierarchical linear regression model indicated that Intensity (ß=0.22), borderline (ß=0.08), eating disorder (ß=0.11) symptoms, as well as Escapism (ß=0.47) and Mood Enhancement (ß=0.15) (as motivational factors) together explained 42% of DAI scores. Dance addiction as assessed with the Dance Addiction Inventory is associated with indicators of mild psychopathology and therefore warrants further research

Analysis of the Trajectory of Drosophila melanogaster in a Circular Open Field Arena

BACKGROUND: Obtaining a complete phenotypic characterization of a freely moving organism is a difficult task, yet such a description is desired in many neuroethological studies. Many metrics currently used in the literature to describe locomotor and exploratory behavior are typically based on average quantities or subjectively chosen spatial and temporal thresholds. All of these measures are relatively coarse-grained in the time domain. It is advantageous, however, to employ metrics based on the entire trajectory that an organism takes while exploring its environment. METHODOLOGY/PRINCIPAL FINDINGS: To characterize the locomotor behavior of Drosophila melanogaster, we used a video tracking system to record the trajectory of a single fly walking in a circular open field arena. The fly was tracked for two hours. Here, we present techniques with which to analyze the motion of the fly in this paradigm, and we discuss the methods of calculation. The measures we introduce are based on spatial and temporal probability distributions and utilize the entire time-series trajectory of the fly, thus emphasizing the dynamic nature of locomotor behavior. Marginal and joint probability distributions of speed, position, segment duration, path curvature, and reorientation angle are examined and related to the observed behavior. CONCLUSIONS/SIGNIFICANCE: The measures discussed in this paper provide a detailed profile of the behavior of a single fly and highlight the interaction of the fly with the environment. Such measures may serve as useful tools in any behavioral study in which the movement of a fly is an important variable and can be incorporated easily into many setups, facilitating high-throughput phenotypic characterization