Underlying modal data issues for detecting damage in truss structures

Independent of the modal identification techniques employed for damage detection, use of measured modal data limits the expectations for damage location. These limitations are examined using the distribution of modal strain energy and the sensitivity of the frequency and mode shapes to structural stiffness changes. For given measured modal information of specific accuracy, this examination reveals the following: (1) damage detection is feasible for members that contribute significantly to the strain energy of the measured modes, (2) the modes which are most effective in detecting damage to certain critical members can be identified, and (3) a relationship can be drawn between the accuracy of the measured modes and frequencies and damage detection feasibility

A Comparative Analysis of Post-Traumatic Stress Syndrome among Individuals Exposed to Different Stressor Events

The purpose of the present study was to compare post-traumatic stress syndrome among persons involved in nine different stressor events: combat in the Vietnam War; rape; serious life-threatening events; divorce; the death of a significant other; critical, near fatal illness of a significant other; family trauma; multiple traumatic events; and no stressful event. To assess the severity of the symptoms which define post-traumatic stress disorder (PTSD), the Impact of Event Scale, the Beck Depression Inventory, the Stress Assessment Scale for PTSD from the Vietnam Era Stress Inventory (Wilson & Krauss, 1980) and the Sensation Seeking Scale were administered to the participants (N=409). A person by situation conceptual model of PTSD was presented from which two major hypotheses were tested. As predicted from the model, the degree of loss of a significant other and life-threat were predictive of syndromespecific symptoms of PTSD. The results of the study strongly support the heuristic value of an interactionist model of PTSD

Experiments for locating damaged truss members in a truss structure

Locating damaged truss members in large space structures will involve a combination of sensing and diagnostic techniques. Methods developed for damage location require experimental verification prior to on-orbit applications. To this end, a series of experiments for locating damaged members using a generic, ten bay truss structure were conducted. A 'damaged' member is a member which has been removed entirely. Previously developed identification methods are used in conjunction with the experimental data to locate damage. Preliminary results to date are included, and indicate that mode selection and sensor location are important issues for location performance. A number of experimental data sets representing various damage configurations were compiled using the ten bay truss. The experimental data and the corresponding finite element analysis models are available to researchers for verification of various methods of structure identification and damage location

Endogenous ROS Levels in C. Elegans Under Exogenous Stress Support Revision of Oxidative Stress Theory of Life-History Tradeoffs

Background: The oxidative stress theory of life-history tradeoffs states that oxidative stress caused by damaging free radicals directly underpins tradeoffs between reproduction and longevity by altering the allocation of energetic resources between these tasks. We test this theory by characterizing the effects of exogenous oxidative insult and its interaction with thermal stress and diet quality on a suite of life-history traits and correlations in Caenorhabditis elegans nematodes. We also quantify demographic aging rates and endogenous reactive oxygen species (ROS) levels in live animals. Results: Our findings indicate a tradeoff between investment in reproduction and antioxidant defense (somatic maintenance) consistent with theoretical predictions, but correlations between standard life-history traits yield little evidence that oxidative stress generates strict tradeoffs. Increasing oxidative insult, however, shows a strong tendency to uncouple positive phenotypic correlations and, in particular, to reduce the correlation between reproduction and lifespan. We also found that mild oxidative insult results in lower levels of endogenous ROS accompanied by hormetic changes in lifespan, demographic aging, and reproduction that disappear in combined-stress treatments–consistent with the oxidative stress theory of aging. Conclusions: Our findings demonstrate that oxidative stress is a direct contributor to life-history trait variation and that traditional tradeoffs are not necessary to invoke oxidative stress as a mediator of relationships between life-history traits, supporting previous calls for revisions to theory

Evaluating Isolation Behaviors by Nurses Using Mobile Computer Workstations at the Bedside.

This secondary analysis from a larger mixed methods study with a sequential explanatory design investigates the clinical challenges for nurses providing patient care, in an airborne and contact isolation room, while using a computer on wheels for medication administration in a simulated setting. Registered nurses, who regularly work in clinical care at the patient bedside, were recruited as study participants in the simulation and debriefing experience. A live volunteer acted as the standardized patient who needed assessment and intravenous pain medication. The simulation was video recorded in a typical hospital room to observe participating nurses conducting patient care in an airborne and contact isolation situation. Participants then reviewed their performance with study personnel in a formal, audio-recorded debriefing. Isolation behaviors were scored by an expert panel, and the debriefing sessions were analyzed. Considerable variation was found in behaviors related to using a computer on wheels while caring for a patient in isolation. Currently, no nursing care guidelines exist on the use of computers on wheels in an airborne and contact isolation room. Specific education is needed on nursing care processes for the proper disinfection of computers on wheels and the reduction of the potential for disease transmission from environmental contamination

Clinical challenges in isolation care

OVERVIEW: In 2014, the authors published the results of a study investigating nurses\u27 use of personal protective equipment (PPE) in the care of a live simulated patient requiring contact and airborne precautions. The 24 participants were video-recorded as they donned and doffed PPE. Variations in practices that had the potential to cause contamination were noted. In this article, the authors comment on those variations, analyzing each element of proper PPE protocols and examining why the behaviors are a safety concern for the nurse and a potential risk for disease transmission in the hospital or other clinical area. The authors note that making use of reflective practice for complicated care situations such as infection control may help nurses improve decision making in isolation care

Method for investigating nursing behaviors related to isolation care.

BACKGROUND: Although an emphasis has been placed on protecting patients by improving health care worker compliance with infection control techniques, challenges associated with patient isolation do exist. To address these issues, a more consistent mechanism to evaluate specific clinical behaviors safely is needed. METHODS: The research method described in this study used a high fidelity simulation using a live standardized patient recorded by small cameras. Immediately after the simulation experience, nurses were asked to view and comment on their performance. A demographic survey and a video recorded physical evaluation provided participant description. A questionnaire component 1 month after the simulation experience offered insight into the timing of behavior change in clinical practice. RESULTS: Errors in behaviors related to donning and doffing equipment for isolation care were noted among the nurses in the study despite knowing they were being video recorded. This simulation-based approach to clinical behavior analysis provided rich data on patient care delivery. CONCLUSION: Standard educational techniques have not led to ideal compliance, and this study demonstrated the potential for using video feedback to enhance learning and ultimately reduce behaviors, which routinely increase the likelihood of disease transmission. This educational research method could be applied to many complicated clinical skills

Framework for the natures of negativity in introductory physics

Mathematical reasoning skills are a desired outcome of many introductory physics courses, particularly calculus-based physics courses. Novices can struggle to understand the many roles signed numbers play in physics contexts, and recent evidence shows that unresolved struggle can carry over to subsequent physics courses. Positive and negative quantities are ubiquitous in physics, and the sign carries important and varied meanings. The mathematics education research literature documents the cognitive challenge of conceptualizing negative numbers as mathematical objects—both for experts, historically, and for novices as they learn. We contribute to the small but growing body of research in physics contexts that examines student reasoning about signed quantities and reasoning about the use and interpretation of signs in mathematical models. In this paper we present a framework for categorizing various meanings and interpretations of the negative sign in physics contexts, inspired by established work in algebraic contexts from the mathematics education research community. Such a framework can support innovation that can catalyze deeper mathematical conceptualizations of signed quantities in the introductory courses and beyond

The K2 Mission: Characterization and Early results

The K2 mission will make use of the Kepler spacecraft and its assets to expand upon Kepler's groundbreaking discoveries in the fields of exoplanets and astrophysics through new and exciting observations. K2 will use an innovative way of operating the spacecraft to observe target fields along the ecliptic for the next 2-3 years. Early science commissioning observations have shown an estimated photometric precision near 400 ppm in a single 30 minute observation, and a 6-hour photometric precision of 80 ppm (both at V=12). The K2 mission offers long-term, simultaneous optical observation of thousands of objects at a precision far better than is achievable from ground-based telescopes. Ecliptic fields will be observed for approximately 75-days enabling a unique exoplanet survey which fills the gaps in duration and sensitivity between the Kepler and TESS missions, and offers pre-launch exoplanet target identification for JWST transit spectroscopy. Astrophysics observations with K2 will include studies of young open clusters, bright stars, galaxies, supernovae, and asteroseismology.Comment: 25 pages, 11 figures, Accepted to PAS