17,596 research outputs found
Additional extensions to the NASCAP computer code, volume 3
The ION computer code is designed to calculate charge exchange ion densities, electric potentials, plasma temperatures, and current densities external to a neutralized ion engine in R-Z geometry. The present version assumes the beam ion current and density to be known and specified, and the neutralizing electrons to originate from a hot-wire ring surrounding the beam orifice. The plasma is treated as being resistive, with an electron relaxation time comparable to the plasma frequency. Together with the thermal and electrical boundary conditions described below and other straightforward engine parameters, these assumptions suffice to determine the required quantities. The ION code, written in ASCII FORTRAN for UNIVAC 1100 series computers, is designed to be run interactively, although it can also be run in batch mode. The input is free-format, and the output is mainly graphical, using the machine-independent graphics developed for the NASCAP code. The executive routine calls the code's major subroutines in user-specified order, and the code allows great latitude for restart and parameter change
Precursor Analysis for Offshore Oil and Gas Drilling: From Prescriptive to Risk-Informed Regulation
The Oil Spill Commission’s chartered mission—to “develop options to guard against … any oil spills associated with offshore drilling in the future” (National Commission 2010)—presents a major challenge: how to reduce the risk of low-frequency oil spill events, and especially high-consequence events like the Deepwater Horizon accident, when historical experience contains few oil spills of material scale and none approaching the significance of the Deepwater Horizon. In this paper, we consider precursor analysis as an answer to this challenge, addressing first its development and use in nuclear reactor regulation and then its applicability to offshore oil and gas drilling. We find that the nature of offshore drilling risks, the operating information obtainable by the regulator, and the learning curve provided by 30 years of nuclear experience make precursor analysis a promising option available to the U.S. Bureau of Ocean Energy Management, Regulation and Enforcement (BOEMRE) to bring cost-effective, risk-informed oversight to bear on the threat of catastrophic oil spills.catastrophic oil spills, quantitative risk analysis, risk-informed regulation
Spacecraft-plasma interaction codes: NASCAP/GEO, NASCAP/LEO, POLAR, DynaPAC, and EPSAT
Development of a computer code to simulate interactions between the surfaces of a geometrically complex spacecraft and the space plasma environment involves: (1) defining the relevant physical phenomena and formulating them in appropriate levels of approximation; (2) defining a representation for the 3-D space external to the spacecraft and a means for defining the spacecraft surface geometry and embedding it in the surrounding space; (3) packaging the code so that it is easy and practical to use, interpret, and present the results; and (4) validating the code by continual comparison with theoretical models, ground test data, and spaceflight experiments. The physical content, geometrical capabilities, and application of five S-CUBED developed spacecraft plasma interaction codes are discussed. The NASA Charging Analyzer Program/geosynchronous earth orbit (NASCAP/GEO) is used to illustrate the role of electrostatic barrier formation in daylight spacecraft charging. NASCAP/low Earth orbit (LEO) applications to the CHARGE-2 and Space Power Experiment Aboard Rockets (SPEAR)-1 rocket payloads are shown. DynaPAC application to the SPEAR-2 rocket payloads is described. Environment Power System Analysis Tool (EPSAT) is illustrated by application to Tethered Satellite System 1 (TSS-1), SPEAR-3, and Sundance. A detailed description and application of the Potentials of Large Objects in the Auroral Region (POLAR) Code are presented
Recommended from our members
Study protocol: Intensive care anxiety and emotional recovery (Icare) - A prospective study
Background
Survivors of intensive care units (ICUs) commonly present with symptoms of anxiety, depression and post-traumatic stress disorder (PTSD) during recovery. A number of factors have been identified as predictors of these adverse emotional outcomes, but the role of state anxiety during critical illness in the development of these emotional problems remains unknown.
Purpose
The Intensive Care Anxiety and Emotional Recovery (ICARe) study protocol proposes the development of a statistical model to determine the relationship between state anxiety during ICU stay and symptoms of anxiety, depression and PTSD at three occasions; after ICU discharge but prior to hospital discharge and at the third and sixth months post ICU discharge.
Methods
Prospective study including adult patients admitted to the ICU of a tertiary metropolitan Australian hospital for ≥24 h who are able to: (1) communicate verbally or nonverbally; (2) understand English and (3) open their eyes spontaneously or in response to voice to respond to the Faces Anxiety Scale (state anxiety assessment). One hundred and seventy patients will be assessed for their levels of state anxiety during their ICU stay to achieve a sample size of about 104 patients six months after discharge. The outcomes of the ICARe study will include symptoms of anxiety, depression and PTSD assessed by standardised questionnaires widely used in intensive care research. Demographic, clinical, and social support information will also be collected.
Results
The projected sample size will provide sufficient power to evaluate the association between state anxiety and adverse emotional outcomes, as well as a variety of variables that will be entered into a multivariate regression analysis.
Conclusion
This study will provide new evidence to improve care during critical illness and reduce adverse outcomes during recovery with the potential to decrease unnecessary suffering, promote comfort and improve long-term recovery
Polar orbit electrostatic charging of objects in shuttle wake
A survey of DMSP data has uncovered several cases where precipitating auroral electron fluxes are both sufficiently intense and energetic to charge spacecraft materials such as teflon to very large potentials in the absence of ambient ion currents. Analytical bounds are provided which show that these measured environments can cause surface potentials in excess of several hundred volts to develop on objects in the orbiter wake for particular vehicle orientations
Comment on "Fisheries Management"
The recent article by O’Leary et al. (2011) raises an important question about the relationship between science and those who manage fisheries. They contend that fishery managers do not give due cognisance to scientific advice and consistently set Total Allowable Catches (TACs) above values advised by scientists (which they define as ‘‘political adjustment’’). The authors claim that the consequence of this is that there is a high probability of stock collapse in the next 40 years. They use a simulation model to argue that this probability may exceed 80% at the mean level of political adjustment adopted by managers, depending on the degree of environmental variability and life history strategy of the fish
Recommended from our members
Strategies to Improve Information Transfer for Multitrauma Patients.
The aim of this multiphase mixed-method study was to improve access, flow, and consistency of information transfer for multitrauma patients leaving the Emergency Department. Methods included literature review, focus group interviews, chart audits, staff surveys, and a review of international trauma forms to inform an intervention developed with a researcher-led, clinician stakeholder group. Analysis included descriptive and inferential statistics. Baseline data revealed variability existed in patient-care documentation, showing little standardization. Improvement strategies implemented included a gold standard for information embedded in handover tools, raising staff awareness of complexities for information transfer. Improvement was seen in communication between wards coordinating transfer, improved documentation, decreased information duplication, improved legibility, and increased ease and efficiency in navigating to key information. Improvement in communication at patient transition is essential to continuity of safe, effective care, and is impacted by complex interactions between multiple factors. Difficulty increases for patients with high acuity
Three-dimensional calculation of shuttle charging in polar orbit
The charged particles environment in polar orbit can be of sufficient intensity to cause spacecraft charging. In order to gain a quantitative understanding of such effects, the Air Force is developing POLAR, a computer code which simulates in three dimensions the electrical interaction of large space vehicles with the polar ionospheric plasma. It models the physical processes of wake generation, ambient ion collection, precipitating auroral electron fluxes, and surface interactions, including secondary electron generation and backscattering, which lead to vehicle charging. These processes may be followed dynamically on a subsecond timescale so that the rapid passage through intense auroral arcs can be simulated. POLAR models the ambient plasma as isotropic Maxwellian electrons and ions (0+, H+), and allows for simultaneous precipitation of power-law, energetic Maxwellian, and accelerated Gaussian distributions of electrons. Magnetic field effects will be modeled in POLAR but are currently ignored
Experiences of obesity among Saudi Arabian women contemplating bariatric surgery: An interpretative phenomenological analysis
This is the author's accepted manuscript. The final published article is available from the link below. Copyright @ 2013 The Authors.This study explored experiences of obesity, its perceived causes and motives for surgery, as described by seven Saudi women contemplating bariatric surgery. The women experienced cultural restrictions on their physical and social activities. Obesity embodied these restrictions, attracting stigma and moral failure. Traditional clothing, foods, hospitality norms and limited outdoor female activities were regarded as barriers to weight loss. Bariatric surgery was chosen to protect health and to access normative female roles. Some were encouraged by relatives who had undergone surgery. Opting for surgery reflected both participants’ sense of powerlessness to self-manage weight and the social acceptability, within their family context, of this biomedical approach
Recommended from our members
Trait anxiety but not state anxiety during critical Illness was associated with anxiety and depression over 6 months after ICU
Objective:
To determine the association between anxiety during critical illness and symptoms of anxiety and depression over 6 months after ICU discharge in survivors of intensive care treatment.
Design:
Longitudinal study.
Setting:
One closed mixed ICU in an adult tertiary hospital in Brisbane, Australia.
Patients:
Participants (n = 141) were adults (≥ 8 yr), admitted to ICU for at least 24 hours, able to communicate either verbally or nonverbally, understand English, and open their eyes spontaneously or in response to voice.
Interventions: None.
Measurements and Main Results:
The outcomes of symptoms of anxiety and depression over 6 months after ICU discharge were assessed using the Hospital Anxiety Depression Scale. The primary variable of interest was anxiety during critical illness. Two components of anxiety (state and trait) were assessed during critical illness using the Faces Anxiety Scale and the trait component of the State-Trait Anxiety Inventory. Perceived social support, cognitive functioning, and posttraumatic stress symptoms were also assessed using standardized instruments. Clinical and demographic data were obtained from patients and medical records. Participants were followed up in hospital wards and at 3 and 6 months after ICU discharge. During ICU treatment, 81 of the 141 participants (57%) reported moderate to severe levels of state anxiety. Of the 92 participants who completed the surveys at the 6-month follow-up, 26 participants (28%) reported symptoms of anxiety and 21 (23%) symptoms of depression. Symptoms of anxiety and depression were strongly correlated in this cohort of survivors. Trait anxiety was significantly associated with both anxiety and depression symptoms over time; however, state anxiety was not associated with either outcome. Participants who reported post-ICU memories of intra-ICU anxiety were significantly more anxious during recovery over 6 months. Cognitive functioning and posttraumatic stress symptoms were both significantly associated with anxiety and depression symptoms over time.
Conclusion:
Symptoms of anxiety and depression are a significant issue for general ICU survivors. Trait anxiety was significantly associated with adverse emotional outcomes over 6 months after ICU discharge. There was also a significant relationship between post-ICU memories of intra-ICU anxiety and anxiety during recovery. Interventions to reduce anxiety during critical illness need to be considered and evaluated for their longer term benefits for survivors of critical illness
- …