Science.gov

Sample records for pressure risk model

  1. Physics-Based Fragment Acceleration Modeling for Pressurized Tank Burst Risk Assessments

    NASA Technical Reports Server (NTRS)

    Manning, Ted A.; Lawrence, Scott L.

    2014-01-01

    As part of comprehensive efforts to develop physics-based risk assessment techniques for space systems at NASA, coupled computational fluid and rigid body dynamic simulations were carried out to investigate the flow mechanisms that accelerate tank fragments in bursting pressurized vessels. Simulations of several configurations were compared to analyses based on the industry-standard Baker explosion model, and were used to formulate an improved version of the model. The standard model, which neglects an external fluid, was found to agree best with simulation results only in configurations where the internal-to-external pressure ratio is very high and fragment curvature is small. The improved model introduces terms that accommodate an external fluid and better account for variations based on circumferential fragment count. Physics-based analysis was critical in increasing the model's range of applicability. The improved tank burst model can be used to produce more accurate risk assessments of space vehicle failure modes that involve high-speed debris, such as exploding propellant tanks and bursting rocket engines.

  2. Modeling the relationship between propagule pressure and invasion risk to inform policy and management.

    PubMed

    Wonham, Marjorie J; Byers, James E; Grosholz, Edwin D; Leung, Brian

    2013-10-01

    Predicting population establishment based on initial population size is a theoretically and empirically challenging problem whose resolution informs a multitude of applications. Indeed, it is a central problem in the management of introduced, endangered, harvested, and pathogenic organisms. We focus here on introduced species. We synthesize the current state of modeling in this predictive enterprise and outline future directions in the application of these models to developing regulations intended to prevent the establishment of invaders. Descriptive and mechanistic models of single-population introductions are fairly well developed and have provided insight into invasion risk in laboratory and field conditions. However, many invasions stem from large-scale and repeated releases of a multitude of species from relatively indiscriminate invasion vectors associated with international trade and travel. Vector-scale models of invasion risk are less well developed and are characterized largely by the use of untested proxy variables for propagule pressure. We illustrate the problems associated with proxy variables and introduce a more mechanistic theoretical formulation characterizing vector-scale invasion pressure in terms of propagule pressure (number of introduced individuals) and colonization pressure (number of introduced species). We outline key questions to be addressed in applying both single-population and vector-scale models to the development of threshold-based invasion regulations. We illustrate these ecological and applied questions using examples from terrestrial, aquatic, and marine systems. We develop in detail examples from ballast-water transport that, as one of the best-characterized global invasion vectors and one that is subject to emerging international threshold-based biosecurity regulations, provides a rich case study.

  3. Dynamic prediction model and risk assessment chart for cardiovascular disease based on on-treatment blood pressure and baseline risk factors.

    PubMed

    Teramukai, Satoshi; Okuda, Yasuyuki; Miyazaki, Shigeru; Kawamori, Ryuzo; Shirayama, Masayuki; Teramoto, Tamio

    2016-02-01

    For patients with hypertension, an individual risk prediction tool for cardiovascular disease based on on-treatment blood pressure is needed and would be useful. The objective of this study was to establish a 3-year risk prediction model for cardiovascular disease based on data from 13 052 patients with no history of cardiovascular disease in the Olmesartan Mega study to determine the relationship between Cardiovascular Endpoints and Blood Pressure Goal Achievement study. To develop dynamic prediction models including on-treatment blood pressure, a Cox proportional hazard model using the sliding landmarking method with three landmark points (6, 12 and 18 months from baseline) was used. The prediction model included blood pressure (<130/85 mm Hg, ⩾130/85  to <140/90 mm Hg, ⩾140/90 to <160/100 mm Hg and ⩾160/100 mm Hg) as a time-dependent covariate and well-known baseline risk factors (sex, age, smoking, family history of coronary artery disease and diabetes) as covariates. The 3-year risk assessment chart was constructed using the combination of all risk factors in the prediction model, and six different colors were displayed on each chart corresponding to the predicted probability of cardiovascular disease. Judging from the chart, if an elderly man with diabetes and other risk factors had a blood pressure of <130/85 mm Hg at 6 months, the risk of cardiovascular disease would be 8.0%, whereas the risk would be 8.6% if he had a blood pressure of ⩾130/85 to <140/90 mm Hg. The risk assessment chart developed from the large-scale observational study data would help physicians to more easily assess the cardiovascular disease risk for hypertensive patients on antihypertensive treatments.

  4. Recording pressure ulcer risk assessment and incidence.

    PubMed

    Plaskitt, Anne; Heywood, Nicola; Arrowsmith, Michaela

    2015-07-15

    This article reports on the introduction of an innovative computer-based system developed to record and report pressure ulcer risk and incidence at an acute NHS trust. The system was introduced to ensure that all patients have an early pressure ulcer risk assessment, which prompts staff to initiate appropriate management if a pressure ulcer is detected, thereby preventing further patient harm. Initial findings suggest that this electronic process has helped to improve the timeliness and accuracy of data on pressure ulcer risk and incidence. In addition, it has resulted in a reduced number of reported hospital-acquired pressure ulcers.

  5. Visual Impairment/Intracranial Pressure Risk Assessment

    NASA Technical Reports Server (NTRS)

    Fogarty, Jennifer A.; Durham, T.; Otto, C.; Grounds, D.; Davis, J. R.

    2010-01-01

    Since 2006 there have been 6 reported cases of altered visual acuity and intracranial pressure (ICP) in long duration astronauts. In order to document this risk and develop an integrated approach to its mitigation, the NASA Space Life Sciences Directorate (SLSD) and Human Research Program (HRP) have chosen to use the Human System Risk Board (HSRB) and the risk management analysis tool (RMAT). The HSRB is the venue in which the stakeholders and customers discuss and vet the evidence and the RMAT is the tool that facilitates documentation and comparison of the evidence across mission profiles as well as identification of risk factors, and documentation of mitigation strategies. This process allows for information to be brought forward and dispositioned so that it may be properly incorporated into the RMAT and contribute to the design of the research and mitigation plans. The evidence thus far has resulted in the identification of a visual impairment/intracranial pressure (VIIP) project team, updating of both short and long duration medical requirements designed to assess visual acuity, and a research plan to characterize this issue further. In order to understand this issue more completely, a plan to develop an Accelerated Research Collaboration (ARC) has been approved by the HSRB. The ARC is a novel research model pioneered by the Myelin Repair Foundation. It is a patient centered research model that brings together researchers and clinicians, under the guidance of a scientific advisory panel, to collaborate and produce results much quickly than accomplished through traditional research models. The data and evidence from the updated medical requirements and the VIIP ARC will be reviewed at the HSRB on a regular basis. Each review package presented to the HSRB will include an assessment and recommendation with respect to continuation of research, countermeasure development, occupational surveillance modalities, selection criteria, etc. This process will determine the

  6. Pressure sore risk assessment in children.

    PubMed

    Waterlow, J A

    1997-07-01

    A multi-centred study was undertaken involving 300 children ranging from neonates to children aged 16 years. The purpose of the study was to investigate the possibility of designing a pressure sore risk assessment scoring system suitable for the paediatric area of care. It was found that the following conclusions can be drawn: (i) Children are at risk of developing pressure sores; (ii) A version of the adult Waterlow card was not appropriate, especially at the younger end of the scale; (iii) There are identifiable situations and treatments which do pose a risk of pressure sore development. Admission documentation and a care plan within a hospital policy is recommended as the best method of drawing nurses' attention to the risk factors involved and the measures which need to be taken to alleviate the risk of tissue damage.

  7. Patient repositioning and pressure ulcer risk--monitoring interface pressures of at-risk patients.

    PubMed

    Peterson, Matthew J; Gravenstein, Nikolaus; Schwab, Wilhelm K; van Oostrom, Johannes H; Caruso, Lawrence J

    2013-01-01

    Repositioning patients regularly to prevent pressure ulcers and reduce interface pressures is the standard of care, yet prior work has found that standard repositioning does not relieve all areas of at-risk tissue in nondisabled subjects. To determine whether this holds true for high-risk patients, we assessed the effectiveness of routine repositioning in relieving at-risk tissue of the perisacral area using interface pressure mapping. Bedridden patients at risk for pressure ulcer formation (n = 23, Braden score <18) had their perisacral skin-bed interface pressures recorded every 30 s while they received routine repositioning care for 4-6 h. All participants had specific skin areas (206 +/- 182 cm(2)) that exceeded elevated pressure thresholds for >95% of the observation period. Thirteen participants were observed in three distinct positions (supine, turned left, turned right), and all had specific skin areas (166 +/- 184 cm(2)) that exceeded pressure thresholds for >95% of the observation period. At-risk patients have skin areas that are likely always at risk throughout their hospital stay despite repositioning. Healthcare providers are unaware of the actual tissue-relieving effectiveness (or lack thereof) of their repositioning interventions, which may partially explain why pressure ulcer mitigation strategies are not always successful. Relieving at-risk tissue is a necessary part of pressure ulcer prevention, but the repositioning practice itself needs improvement.

  8. Designing trials for pressure ulcer risk assessment research: methodological challenges.

    PubMed

    Balzer, K; Köpke, S; Lühmann, D; Haastert, B; Kottner, J; Meyer, G

    2013-08-01

    For decades various pressure ulcer risk assessment scales (PURAS) have been developed and implemented into nursing practice despite uncertainty whether use of these tools helps to prevent pressure ulcers. According to current methodological standards, randomised controlled trials (RCTs) are required to conclusively determine the clinical efficacy and safety of this risk assessment strategy. In these trials, PURAS-aided risk assessment has to be compared to nurses' clinical judgment alone in terms of its impact on pressure ulcer incidence and adverse outcomes. However, RCTs evaluating diagnostic procedures are prone to specific risks of bias and threats to the statistical power which may challenge their validity and feasibility. This discussion paper critically reflects on the rigour and feasibility of experimental research needed to substantiate the clinical efficacy of PURAS-aided risk assessment. Based on reflections of the methodological literature, a critical appraisal of available trials on this subject and an analysis of a protocol developed for a methodologically robust cluster-RCT, this paper arrives at the following conclusions: First, available trials do not provide reliable estimates of the impact of PURAS-aided risk assessment on pressure ulcer incidence compared to nurses' clinical judgement alone due to serious risks of bias and insufficient sample size. Second, it seems infeasible to assess this impact by means of rigorous experimental studies since sample size would become extremely high if likely threats to validity and power are properly taken into account. Third, means of evidence linkages seem to currently be the most promising approaches for evaluating the clinical efficacy and safety of PURAS-aided risk assessment. With this kind of secondary research, the downstream effect of use of PURAS on pressure ulcer incidence could be modelled by combining best available evidence for single parts of this pathway. However, to yield reliable modelling

  9. Hurricane risk mitigation - High Pressure Gas Facility

    NASA Technical Reports Server (NTRS)

    2008-01-01

    A worker pours concrete as part of a nitrogen risk mitigation project at the High Pressure Gas Facility at Stennis Space Center. The concrete slab will provide the foundation needed to place new pumps at the site and is part of ongoing hurricane-related mitigation work at Stennis.

  10. [Elevated blood pressure as cardiovascular risk factor].

    PubMed

    Kowalewski, Wiesław; Hebel, Kazimiera

    2013-01-01

    Cardiovascular diseases for decades have been and still are the main and current health problem of the Polish society and there are many reasons for these diseases. Hypertension is one of the major risk factors for developing cardiovascular disease. The factors significantly increasing risk the of cardiovascular disease are in addition to high blood pressure, smoking (also passive), high blood fats (cholesterol and its HDL, LDL fractions as well as triglyceride levels, obesity, lack of exercise, diabetes and hereditary features. Other important factors which play an important role are external factors such as e.g. environmental pollution, lifestyle, stress. Prediction of cardiovascular disease should start from the evaluation of the fetal period because low birth weight may be a risk of coronary heart disease, hypertension, obesity or diabetes in adulthood. The authors of the referred tests showed that the level of blood pressure observed during childhood is closely associated with the level of blood pressure in adults and is also dependent on the body weight. Since the issue of the effects of high pressure on the cardiovascular system is inherent in the issue of the metabolic syndrome, it should be mentioned also that another causative factor may be an irregularity in the removal of urine from the body and the amount of insulin. The control of hypertension is a complex problem, at least in view of the wide range of adverse factors affecting the human body: hypertension is often either a constituent of other lesions. Therefore, it is difficult to treat high blood pressure in the strict sense; more often it is a combination therapy based on pharmacology caused for other reasons.

  11. Melanoma Risk Prediction Models

    Cancer.gov

    Developing statistical models that estimate the probability of developing melanoma cancer over a defined period of time will help clinicians identify individuals at higher risk of specific cancers, allowing for earlier or more frequent screening and counseling of behavioral changes to decrease risk.

  12. Risk Factors for High Blood Pressure

    MedlinePlus

    ... to achieve target blood pressure goals with treatment. Overweight You are more likely to develop prehypertension or high blood pressure if you’re overweight or obese . The terms “overweight” and “obese” refer ...

  13. Blood Pressure and Global Risk Assessment in a Swedish Population

    PubMed Central

    Eckner, Jenny; Larsson, Charlotte A.; Råstam, Lennart; Lindblad, Ulf

    2012-01-01

    This study investigated the association between SCORE and the 2007 ESH-ESC blood pressure categories and explored achievements of blood pressure goals considering global risk. In 2001–2005, a random sample of inhabitants aged 30–74 years in southwestern Sweden was invited to a survey of cardiovascular risk factors. The study enrolled 2816 participants (participation rate 76%). Blood pressure was categorized according to the 2007 ESH-ESC guidelines. Global risk of 10-year CVD death was estimated using the Swedish SCORE chart also accounting for additional risk from diabetes (SCORE-DM). SCORE-DM increased in both sexes from optimal blood pressure to manifest hypertension but did not differ between the normal blood pressure categories. However, SCORE-DM became significantly higher among those with temporarily high blood pressure (men 3.3 SD (1.7), women 1.1 (1.8)) and hypertension (3.6 (2.0), 2.0 (2.0)), compared to optimal blood pressure (1.6 (2.9), 0.6 (1.9)). In the presence of both hypertension and diabetes, high-risk subjects dominated (men 76%, women 61%), and correspondingly a major proportion of patients with known hypertension were at high risk at a blood pressure ≥160/100 mm Hg. These findings have strong implications on blood pressure evaluation in clinical practice and support the use of SCORE to evaluate global risk. PMID:22991653

  14. ``Swiss cheese'' models with pressure

    NASA Astrophysics Data System (ADS)

    Bona, C.; Stela, J.

    1987-11-01

    Local spherically symmetric inhomogeneities are matched to a spatially flat Robertson-Walker background with pressure. In the cases in which the background evolves to an Einstein-de Sitter dust universe, the interior metrics tend with time either to the vacuum Schwarzschild solution or to the spatially flat Tolman dust metrics. The whole construction may be interpreted as the history of the dust-filled ``Swiss cheese'' models.

  15. General Pressurization Model in Simscape

    NASA Technical Reports Server (NTRS)

    Servin, Mario; Garcia, Vicky

    2010-01-01

    System integration is an essential part of the engineering design process. The Ares I Upper Stage (US) is a complex system which is made up of thousands of components assembled into subsystems including a J2-X engine, liquid hydrogen (LH2) and liquid oxygen (LO2) tanks, avionics, thrust vector control, motors, etc. System integration is the task of connecting together all of the subsystems into one large system. To ensure that all the components will "fit together" as well as safety and, quality, integration analysis is required. Integration analysis verifies that, as an integrated system, the system will behave as designed. Models that represent the actual subsystems are built for more comprehensive analysis. Matlab has been an instrument widely use by engineers to construct mathematical models of systems. Simulink, one of the tools offered by Matlab, provides multi-domain graphical environment to simulate and design time-varying systems. Simulink is a powerful tool to analyze the dynamic behavior of systems over time. Furthermore, Simscape, a tool provided by Simulink, allows users to model physical (such as mechanical, thermal and hydraulic) systems using physical networks. Using Simscape, a model representing an inflow of gas to a pressurized tank was created where the temperature and pressure of the tank are measured over time to show the behavior of the gas. By further incorporation of Simscape into model building, the full potential of this software can be discovered and it hopefully can become a more utilized tool.

  16. Biosafety Risk Assessment Model

    SciTech Connect

    Daniel Bowen, Susan Caskey

    2011-05-27

    Software tool based on a structured methodology for conducting laboratory biosafety risk assessments by biosafety experts. Software is based upon an MCDA scheme and uses peer reviewed criteria and weights. The software was developed upon Microsoft’s .net framework. The methodology defines likelihood and consequence of a laboratory exposure for thirteen unique scenarios and provides numerical relative risks for each of the relevant thirteen. The software produces 2-d graphs reflecting the relative risk and a sensitivity analysis which highlights the overall importance of each factor. The software works as a set of questions with absolute scales and uses a weighted additive model to calculate the likelihood and consequence.

  17. Nanotechnologies: Risk assessment model

    NASA Astrophysics Data System (ADS)

    Giacobbe, F.; Monica, L.; Geraci, D.

    2009-05-01

    The development and use of nanomaterials has grown widely in the last years. Hence, it is necessary to carry out a careful and aimed risk assessment for the safety of the workers. The objective of this research is a specific assessment model finalized to the workplaces where the personnel work manipulating nanoparticles. This model mainly takes into account the number of exposed workers, the dimensions of particles, the information found in the safety data sheets and the uncertainties about the danger level coming from the exposition to nanomaterials. The evaluation algorithm considers the normal work conditions, the abnormal (e.g. breakdown air filter) and emergency situations (e.g. package cracking). It has been necessary to define several risk conditions in order to quantify the risk by increasing levels ("low", "middle" and "high" level). Each level includes appropriate behavioural procedures. In particular for the high level, it is advisable that the user carries out urgent interventions finalized to reduce the risk level (e.g. the utilization of vacuum box for the manipulation, high efficiency protection PPE, etc). The model has been implemented in a research laboratory where titanium dioxide and carbon nanotubes are used. The outcomes taken out from such specific evaluation gave a risk level equal to middle.

  18. Pore pressure propagation in a permeable thin-layer coal seam based on a dual porosity model: A case of risk prediction of water inrush in coalmines

    NASA Astrophysics Data System (ADS)

    Zhu, B.; Gao, F.; Yang, J. W.; Zhou, G. Q.

    2016-08-01

    Thin-layer coal seams, a type of filling coal rock body, are considered aquifer systems made up of dual porosity medium with immediate floor. A numerical simulation for the pore pressure propagation along a thin-layer coal seam was carried out for the case of the Zhaogezhuang coalmine in China. By valuing the permeability (Kf ) of the thin-layer coal seam, pore pressure variation with time was simulated and compared to the analytical solutions of a dual porosity model (DPM). The main conclusions were drawn as follow: (1) Seepage in the thin-layer coal seam was predominant in the whole process, and the distance of seepage was lengthened and the pore pressure decreased with increased Kf , (2) A series of simulated hydraulic graphs demonstrated that the pore pressure characteristics of peak-occurring and time-lag effects agreed with the analytical solutions of DPM; (3) By adjusting the parameters of DPM, two results of analytical solutions and numerical solutions fit well, particularly in the thin-layer coal seam, (4) The power law relationship between the peak-values and lag time of pore pressure were derived statistically under consideration of the Kf parameter in the range of 10-8 to 10-10 m2/pa-s orders, and it was reasonable that the Kf of the thin-layer coal seam was in the range of 10-8 m2/pa-s orders. The results were significantly helpful in decision-making for mining water prevention and prediction in practice.

  19. Pressure ulcer risk of patient handling sling use.

    PubMed

    Peterson, Matthew J; Kahn, Julie A; Kerrigan, Michael V; Gutmann, Joseph M; Harrow, Jeffrey J

    2015-01-01

    Patient handling slings and lifts reduce the risk of musculoskeletal injuries for healthcare providers. However, no published evidence exists of their safety with respect to pressure ulceration for vulnerable populations, specifically persons with spinal cord injury, nor do any studies compare slings for pressure distribution. High-resolution interface pressure mapping was used to describe and quantify risks associated with pressure ulceration due to normal forces and identify at-risk anatomical locations. We evaluated 23 patient handling slings with 4 nondisabled adults. Sling-participant interface pressures were recorded while participants lay supine on a hospital bed and while suspended during typical patient transfers. Sling-participant interface pressures were greatest while suspended for all seated and supine slings and exceeded 200 mm Hg for all seated slings. Interface pressures were greatest along the sling seams (edges), regardless of position or sling type. The anatomical areas most at risk while participants were suspended in seated slings were the posterior upper and lower thighs. For supine slings, the perisacral area, ischial tuberosities, and greater trochanters were most at risk. The duration of time spent in slings, especially while suspended, should be limited.

  20. Clustering-based limb identification for pressure ulcer risk assessment.

    PubMed

    Baran Pouyan, M; Nourani, M; Pompeo, M

    2015-01-01

    Bedridden patients have a high risk of developing pressure ulcers. Risk assessment for pressure ulceration is critical for preventive care. For a reliable assessment, we need to identify and track the limbs continuously and accurately. In this paper, we propose a method to identify body limbs using a pressure mat. Three prevalent sleep postures (supine, left and right postures) are considered. Then, predefined number of limbs (body parts) are identified by applying Fuzzy C-Means (FCM) clustering on key attributes. We collected data from 10 adult subjects and achieved average accuracy of 93.2% for 10 limbs in supine and 7 limbs in left/right postures.

  1. Modeling the Effects of Moisture-Related Skin-Support Friction on the Risk for Superficial Pressure Ulcers during Patient Repositioning in Bed

    PubMed Central

    Shaked, Eliav; Gefen, Amit

    2013-01-01

    Patient repositioning when the skin is moist, e.g., due to sweat or urine may cause skin breakdown since wetness increases the skin-support coefficient of friction (COF) and hence also the shear stresses that are generated in the skin when the patient is being moved. This everyday hospital scenario was never studied systematically however. The aim of this study was to simulate such interactions using a biomechanical computational model which is the first of its kind, in order to quantitatively describe the effects of repositioning on the pathomechanics of moisture-related tissue damage. We designed a finite element model to analyze skin stresses under a weight-bearing bony prominence while this region of interest slides frictionally over the support surface, as occurs during repositioning. Our results show, expectedly, that maximal effective stresses in the skin increase as the moisture-contents-related COF between the skin and the mattress rises. Interestingly however, the rise in stresses for a wet interface became more prominent when the skin tissue was stiffer – which represented aging or diabetes. This finding demonstrates how the aged/diabetic skin is more fragile than a young-adult skin when repositioning in a moist environment. The modeling used herein can now be extended to test effects of different moisturizers, creams, lubricants, or possibly other interventions at the skin-support interface for testing their potential in protecting the skin from superficial pressure ulcers in a standard, objective, and quantitative manner. PMID:25022867

  2. Pressure Systems Stored-Energy Threshold Risk Analysis

    SciTech Connect

    Paulsen, Samuel S.

    2009-08-25

    Federal Regulation 10 CFR 851, which became effective February 2007, brought to light potential weaknesses regarding the Pressure Safety Program at the Pacific Northwest National Laboratory (PNNL). The definition of a pressure system in 10 CFR 851 does not contain a limit based upon pressure or any other criteria. Therefore, the need for a method to determine an appropriate risk-based hazard level for pressure safety was identified. The Laboratory has historically used a stored energy of 1000 lbf-ft to define a pressure hazard; however, an analytical basis for this value had not been documented. This document establishes the technical basis by evaluating the use of stored energy as an appropriate criterion to establish a pressure hazard, exploring a suitable risk threshold for pressure hazards, and reviewing the methods used to determine stored energy. The literature review and technical analysis concludes the use of stored energy as a method for determining a potential risk, the 1000 lbf-ft threshold, and the methods used by PNNL to calculate stored energy are all appropriate. Recommendations for further program improvements are also discussed

  3. Acute radiation risk models

    NASA Astrophysics Data System (ADS)

    Smirnova, Olga

    Biologically motivated mathematical models, which describe the dynamics of the major hematopoietic lineages (the thrombocytopoietic, lymphocytopoietic, granulocytopoietic, and erythropoietic systems) in acutely/chronically irradiated humans are developed. These models are implemented as systems of nonlinear differential equations, which variables and constant parameters have clear biological meaning. It is shown that the developed models are capable of reproducing clinical data on the dynamics of these systems in humans exposed to acute radiation in the result of incidents and accidents, as well as in humans exposed to low-level chronic radiation. Moreover, the averaged value of the "lethal" dose rates of chronic irradiation evaluated within models of these four major hematopoietic lineages coincides with the real minimal dose rate of lethal chronic irradiation. The demonstrated ability of the models of the human thrombocytopoietic, lymphocytopoietic, granulocytopoietic, and erythropoietic systems to predict the dynamical response of these systems to acute/chronic irradiation in wide ranges of doses and dose rates implies that these mathematical models form an universal tool for the investigation and prediction of the dynamics of the major human hematopoietic lineages for a vast pattern of irradiation scenarios. In particular, these models could be applied for the radiation risk assessment for health of astronauts exposed to space radiation during long-term space missions, such as voyages to Mars or Lunar colonies, as well as for health of people exposed to acute/chronic irradiation due to environmental radiological events.

  4. Modeling Cyclic Variation of Intracranial Pressure

    DTIC Science & Technology

    2001-10-25

    with increasing vascular dilation induced by increasing the level of the partial pressure of carbon dioxide (PCO2) within the arterial blood ...ventilation. Simulated model recordings demonstrated that the correlation index between arterial blood pressure and ICP progressively increased... blood pressure (ABP) recording, the ICP Figure 1. Experimental Recordings of ABP and ICP during Normocapnia and Hypercapnia. a) Normocapnia with

  5. A Retrospective Analysis of Pressure Ulcer Incidence and Modified Braden Scale Score Risk Classifications.

    PubMed

    Chen, Hong-Lin; Cao, Ying-Juan; Wang, Jing; Huai, Bao-Sha

    2015-09-01

    The Braden Scale is the most widely used pressure ulcer risk assessment in the world, but the currently used 5 risk classification groups do not accurately discriminate among their risk categories. To optimize risk classification based on Braden Scale scores, a retrospective analysis of all consecutively admitted patients in an acute care facility who were at risk for pressure ulcer development was performed between January 2013 and December 2013. Predicted pressure ulcer incidence first was calculated by logistic regression model based on original Braden score. Risk classification then was modified based on the predicted pressure ulcer incidence and compared between different risk categories in the modified (3-group) classification and the traditional (5-group) classification using chi-square test. Two thousand, six hundred, twenty-five (2,625) patients (mean age 59.8 ± 16.5, range 1 month to 98 years, 1,601 of whom were men) were included in the study; 81 patients (3.1%) developed a pressure ulcer. The predicted pressure ulcer incidence ranged from 0.1% to 49.7%. When the predicted pressure ulcer incidence was greater than 10.0% (high risk), the corresponding Braden scores were less than 11; when the predicted incidence ranged from 1.0% to 10.0% (moderate risk), the corresponding Braden scores ranged from 12 to 16; and when the predicted incidence was less than 1.0% (mild risk), the corresponding Braden scores were greater than 17. In the modified classification, observed pressure ulcer incidence was significantly different between each of the 3 risk categories (P less than 0.05). However, in the traditional classification, the observed incidence was not significantly different between the high-risk category and moderate-risk category (P less than 0.05) and between the mild-risk category and no-risk category (P less than 0.05). If future studies confirm the validity of these findings, pressure ulcer prevention protocols of care based on Braden Scale scores can

  6. Pressure ulcer prevalence and risk factors during prolonged surgical procedures.

    PubMed

    Primiano, Mike; Friend, Michael; McClure, Connie; Nardi, Scott; Fix, Lisa; Schafer, Marianne; Savochka, Kathlyn; McNett, Molly

    2011-12-01

    Pressure ulcer formation related to positioning while in the OR increases the length of hospital stay and hospital costs, but there is little evidence documenting how positioning devices used in the OR influence pressure ulcer development when examined with traditional risk factors. The aim of this prospective cohort study was to identify the prevalence of and risk factors associated with pressure ulcer development among patients undergoing surgical procedures lasting longer than three hours. Participants included all adult same-day admission patients scheduled for a three-hour surgical procedure during an eight-month period (N = 258). Data were gathered preoperatively, intraoperatively, and postoperatively on pressure ulcer risk factors. Bivariate analyses indicated that the type of positioning (ie, heels elevated) (χ(2) = 7.897, P = .048), OR bed surface (ie, foam table pad) (χ(2) = 15.848, P = .000), skin assessment in the postanesthesia care unit (χ(2) = 41.652, P = .000), and male gender (χ(2) = 6.984, P = .030) were associated with pressure ulcer development. Logistic regression analyses indicated that the use of a foam pad (β = 2.691, P = .024) and a lower day-one Braden score (β = .244, P = .003) were predictive of pressure ulcers.

  7. Managing risks from virus intrusion into water distribution systems due to pressure transients.

    PubMed

    Yang, Jian; LeChevallier, Mark W; Teunis, Peter F M; Xu, Minhua

    2011-06-01

    Low or negative pressure transients in water distribution systems, caused by unexpected events (e.g. power outages) or routine operation/maintenance activities, are usually brief and thus are rarely monitored or alarmed. Previous studies have shown connections between negative pressure events in water distribution systems and potential public health consequences. Using a quantitative microbial risk assessment (QMRA) model previously developed, various factors driving the risk of viral infection from intrusion were evaluated, including virus concentrations external to the distribution system, maintenance of a disinfectant residual, leak orifice sizes, the duration and the number of nodes drawing negative pressures. The most sensitive factors were the duration and the number of nodes drawing negative pressures, indicating that mitigation practices should be targeted to alleviate the severity of low/negative pressure transients. Maintaining a free chlorine residual of 0.2 mg/L or above is the last defense against the risk of viral infection due to negative pressure transients. Maintaining a chloramine residual did not appear to significantly reduce the risk. The effectiveness of ensuring separation distances from sewer mains to reduce the risk of infection may be system-specific. Leak detection/repair and cross-connection control should be prioritized in areas vulnerable to negative pressure transients.

  8. Modeling systolic pressure variation due to positive pressure ventilation.

    PubMed

    Messerges, Joanne

    2006-01-01

    Although many clinical techniques have been proposed to assess blood volume none have been established as an undisputed standard practice, Volume studies suggest systolic pressure variation (SPV) as a promising volume indicator but underlying influences on SPV are not well understood. Successful modeling of SPV will reveal the major SPV influencers, guide algorithm development to accommodate these influencers, and potentially lead to a more clinically relevant interpretation of SPV values, thus improving upon current clinical methods for assessing blood volume. This study takes a first step towards identifying SPV influencers by investigating three variations of an existing pressure-flow cardiovascular model. Each successive version introduces an additional modification in attempt to model SPV under normovolemic and hypovolemic conditions, where the last model accounts for positive pressure ventilation, venous compression, and a rightward septum shift. Under normovolemic conditions, each model yields SPV values of 5.8, 6.4, and 6.7 mmHg, respectively. Under hypovolemic conditions the results do not agree with clinical findings, suggesting these three mechanisms alone do not dictate the clinical SPV response to a decrease in volume. Model results are used to suggest improvements for future work.

  9. Risk Associated with Pulse Pressure on Out-of-Office Blood Pressure Measurement

    PubMed Central

    Gu, Yu-Mei; Aparicio, Lucas S.; Liu, Yan-Ping; Asayama, Kei; Hansen, Tine W.; Niiranen, Teemu J.; Boggia, José; Thijs, Lutgarde; Staessen, Jan A.

    2014-01-01

    Background Longitudinal studies have demonstrated that the risk of cardiovascular disease increases with pulse pressure (PP). However, PP remains an elusive cardiovascular risk factor with findings being inconsistent between studies. The 2013 ESH/ESC guideline proposed that PP is useful in stratification and suggested a threshold of 60 mm Hg, which is 10 mm Hg higher compared to that in the 2007 guideline; however, no justification for this increase was provided. Methodology Published thresholds of PP are based on office blood pressure measurement and often on arbitrary categorical analyses. In the International Database on Ambulatory blood pressure in relation to Cardiovascular Outcomes (IDACO) and the International Database on HOme blood pressure in relation to Cardiovascular Outcome (IDHOCO), we determined outcome-driven thresholds for PP based on ambulatory or home blood pressure measurement, respectively. Results The main findings were that for people aged <60 years, PP did not refine risk stratification, whereas in older people the thresholds were 64 and 76 mm Hg for the ambulatory and home PP, respectively. However, PP provided little added predictive value over and beyond classical risk factors. PMID:26587443

  10. SAPPIRE: a prototype mobile tool for pressure ulcer risk assessment.

    PubMed

    Kim, Hyeoneui; Chung, Heejoon; Wang, Shuang; Jiang, Xiaoqian; Choi, Jeeyae

    2014-01-01

    Accurate assessment and documentation of skin conditions facilitate communication among care providers and are critical to effective prevention and mitigation of pressure ulcer. We report developing a prototype mobile system called SAPPIRE (Skin Assessment for Pressure Ulcer Prevention, an Integrated Recording Environment) for an android device to assist nurses with skin assessment and documentation at bedside. SAPPIRE demonstrates (1) data documentation conforming to the relevant terminology standards, (2) data exchange using Continuity of Care Records (CCR) standard and (3) smart display of patient data relevant to risk parameters to promote accurate pressure ulcer risk assessment with the Braden scale. Challenges associated standardizing assessment data faced during this development and the approaches that SAPPIRE took to overcome them are described.

  11. Modeling Scala Media as a Pressure Vessel

    NASA Astrophysics Data System (ADS)

    Lepage, Eric; Olofsson, A.˚Ke

    2011-11-01

    The clinical condition known as endolymphatic hydrops is the swelling of scala media and may result in loss in hearing sensitivity consistent with other forms of low-frequency biasing. Because outer hair cells (OHCs) are displacement-sensitive and hearing levels tend to be preserved despite large changes in blood pressure and CSF pressure, it seems unlikely that the OHC respond passively to changes in static pressures in the chambers. This suggests the operation of a major feedback control loop which jointly regulates homeostasis and hearing sensitivity. Therefore the internal forces affecting the cochlear signal processing amplifier cannot be just motile responses. A complete account of the cochlear amplifier must include static pressures. To this end we have added a third, pressure vessel to our 1-D 140-segment, wave-digital filter active model of cochlear mechanics, incorporating the usual nonlinear forward transduction. In each segment the instantaneous pressure is the sum of acoustic pressure and global static pressure. The object of the model is to maintain stable OHC operating point despite any global rise in pressure in the third chamber. Such accumulated pressure is allowed to dissipate exponentially. In this first 3-chamber implementation we explore the possibility that acoustic pressures are rectified. The behavior of the model is critically dependent upon scaling factors and time-constants, yet by initial assumption, the pressure tends to accumulate in proportion to sound level. We further explore setting of the control parameters so that the accumulated pressure either stays within limits or may rise without bound.

  12. Carotid Stenosis and Ocular Blood Pressure Modelling

    PubMed Central

    Jullian, M.; Kinsner, W.

    1984-01-01

    A model of the human carotid vascular system was developed to study the effects of carotid stenosis on ocular blood pressure and ocular pulse waveform. The model incorporates a non-linear element representing a stenosis. A state variable representation of a reduced model is used in a computer simulation. Results show that carotid stenosis as low as 20% are detectable in the ocular blood pressure waveform.

  13. Model-based setting of inspiratory pressure and respiratory rate in pressure-controlled ventilation.

    PubMed

    Schranz, C; Becher, T; Schädler, D; Weiler, N; Möller, K

    2014-03-01

    Mechanical ventilation carries the risk of ventilator-induced-lung-injury (VILI). To minimize the risk of VILI, ventilator settings should be adapted to the individual patient properties. Mathematical models of respiratory mechanics are able to capture the individual physiological condition and can be used to derive personalized ventilator settings. This paper presents model-based calculations of inspiration pressure (pI), inspiration and expiration time (tI, tE) in pressure-controlled ventilation (PCV) and a retrospective evaluation of its results in a group of mechanically ventilated patients. Incorporating the identified first order model of respiratory mechanics in the basic equation of alveolar ventilation yielded a nonlinear relation between ventilation parameters during PCV. Given this patient-specific relation, optimized settings in terms of minimal pI and adequate tE can be obtained. We then retrospectively analyzed data from 16 ICU patients with mixed pathologies, whose ventilation had been previously optimized by ICU physicians with the goal of minimization of inspiration pressure, and compared the algorithm's 'optimized' settings to the settings that had been chosen by the physicians. The presented algorithm visualizes the patient-specific relations between inspiration pressure and inspiration time. The algorithm's calculated results highly correlate to the physician's ventilation settings with r = 0.975 for the inspiration pressure, and r = 0.902 for the inspiration time. The nonlinear patient-specific relations of ventilation parameters become transparent and support the determination of individualized ventilator settings according to therapeutic goals. Thus, the algorithm is feasible for a variety of ventilated ICU patients and has the potential of improving lung-protective ventilation by minimizing inspiratory pressures and by helping to avoid the build-up of clinically significant intrinsic positive end-expiratory pressure.

  14. Concordance of Shape Risk Scale, a new pressure ulcer risk tool, with Braden Scale.

    PubMed

    Soppi, Esa T; Iivanainen, Ansa K; Korhonen, Pasi A

    2014-12-01

    The occurrence of pressure ulcers was examined in a cross-sectional study in 23 health care facilities and in home care involving 548 patients. The screening of pressure ulcer risk was assessed simultaneously using the Braden Scale and the new Shape Risk Scale (SRS), and the results were compared. The overall prevalence of pressure ulcers in the study population was 15·5% (85/548). The Braden Scale was performed as described in the literature. The direct concordance of the Braden and SRS scales was 46%. In more than 90% of cases, the SRS classified patients as well as or better than the Braden Scale. The SRS allocates patients significantly different from the Braden Scale into the risk categories, especially the difference is significant between the low and medium-risk categories. The greatest advantage of SRS to Braden Scale is that it correctly identifies patients with low risk of pressure ulcers. It is interesting that the two risk scores, taking into consideration the basically different pathophysiological factors, can still give rather similar results. The users considered that both scales are easy to use.

  15. Postprandial Glucose as a Risk Factor for Elevated Intraocular Pressure

    PubMed Central

    Wu, Chen-Jung; Fang, Wen-Hui; Kao, Tung-Wei; Chen, Ying-Jen; Liaw, Fang-Yih; Chang, Yaw-Wen; Wang, Gia-Chi; Peng, Tao-Chun; Chen, Wei-Liang

    2016-01-01

    The aim of this study was to investigate the association between postprandial glucose and intraocular pressure in a relatively healthy population. We examined 1,439 adults getting a health check-up in a health promotion center at Tri-Service General Hospital (TSGH) in Taiwan between 2012 and 2013. All participants underwent examinations to measure metabolic variables and intraocular pressure. Multiple linear regression analyses were performed to assess the relationship between postprandial glucose and intraocular pressure. The levels of postprandial glucose were divided into quartiles with subjects in the lowest quartile being regarded as the reference group to perform quartile-based analysis. Covariate adjustment was designed for three models for further analysis. Subjects with higher quartiles of postprandial glucose level had a higher systolic blood pressure, a greater waist circumference and an elevated fasting glucose level (all p < 0.001). The β coefficient with adjusted covariates showed a significant positive association between postprandial glucose and intraocular pressure. The trends of intraocular pressure across increasing quartiles of postprandial glucose were statistically significant (all p for trend < 0.001). Thus, higher levels of postprandial glucose positively correlated with elevated intraocular pressure. PMID:27977733

  16. Combined impact of lead, cadmium, polychlorinated biphenyls and non-chemical risk factors on blood pressure in NHANES

    SciTech Connect

    Peters, Junenette L. Patricia Fabian, M. Levy, Jonathan I.

    2014-07-15

    High blood pressure is associated with exposure to multiple chemical and non-chemical risk factors, but epidemiological analyses to date have not assessed the combined effects of both chemical and non-chemical stressors on human populations in the context of cumulative risk assessment. We developed a novel modeling approach to evaluate the combined impact of lead, cadmium, polychlorinated biphenyls (PCBs), and multiple non-chemical risk factors on four blood pressure measures using data for adults aged ≥20 years from the National Health and Nutrition Examination Survey (1999–2008). We developed predictive models for chemical and other stressors. Structural equation models were applied to account for complex associations among predictors of stressors as well as blood pressure. Models showed that blood lead, serum PCBs, and established non-chemical stressors were significantly associated with blood pressure. Lead was the chemical stressor most predictive of diastolic blood pressure and mean arterial pressure, while PCBs had a greater influence on systolic blood pressure and pulse pressure, and blood cadmium was not a significant predictor of blood pressure. The simultaneously fit exposure models explained 34%, 43% and 52% of the variance for lead, cadmium and PCBs, respectively. The structural equation models were developed using predictors available from public data streams (e.g., U.S. Census), which would allow the models to be applied to any U.S. population exposed to these multiple stressors in order to identify high risk subpopulations, direct intervention strategies, and inform public policy. - Highlights: • We evaluated joint impact of chemical and non-chemical stressors on blood pressure. • We built predictive models for lead, cadmium and polychlorinated biphenyls (PCBs). • Our approach allows joint evaluation of predictors from population-specific data. • Lead, PCBs and established non-chemical stressors were related to blood pressure.

  17. RISK 0301 - MOLECULAR MODELING

    EPA Science Inventory

    Risk assessment practices, in general, for a range of diseases now encourages the use of mechanistic data to enhance the ability to predict responses at low, environmental exposures. In particular, the pathway from normal biology to pathologic state can be dcscribed by a set of m...

  18. Association of blood pressure and hypertension with the risk of Parkinson disease: the National FINRISK Study.

    PubMed

    Qiu, Chengxuan; Hu, Gang; Kivipelto, Miia; Laatikainen, Tiina; Antikainen, Riitta; Fratiglioni, Laura; Jousilahti, Pekka; Tuomilehto, Jaakko

    2011-06-01

    Cardiovascular risk factors, such as diabetes mellitus and central obesity, have been associated with Parkinson disease (PD), but data on blood pressure and PD are lacking. We sought to examine the association of blood pressure and hypertension with the risk of PD among men and women. This study consisted of 7 surveys (1972-2002) on representative samples of the general population in Finland (National FINRISK Study). A total number of 59 540 participants (age 25 to 74 years; 51.8% women) who were free of PD and stroke at baseline were prospectively followed until December 31, 2006, to identify incident PD cases using the National Social Insurance Register database. Cox proportional hazards models were constructed to estimate the hazard ratio of PD associated with blood pressure. During a mean follow-up period of 18.8 years (SD: 10.2 years), 423 men and 371 women were ascertained to have developed PD. In women, compared with normotensive subjects (<130/80 mm Hg), the multivariable-adjusted hazard ratios of PD associated with high-normal blood pressure (130 to 139/80 to 89 mm Hg) and hypertension (≥140/90 mm Hg or use of antihypertensive agents) were 1.63 (95% CI: 1.07 to 2.47) and 1.62 (95% CI: 1.09 to 2.42). There was no significant association between blood pressure and PD risk in men. The multivariable-adjusted hazard ratios of PD associated with use of antihypertensive agents were 1.08 (95% CI: 0.79 to 1.48) in men and 1.03 (95% CI: 0.76 to 1.38) in women. This study suggests that, in women, above-optimal blood pressure, including high-normal blood pressure and hypertension, is associated with an increased risk of PD. Optimal control of blood pressure in women may reduce the incidence of PD.

  19. Leisure-Time Exercise Could Lower Your Risk of High Blood Pressure

    MedlinePlus

    ... exercise could lower your risk of high blood pressure American Heart Association Rapid Access Journal Report September ... Heart Association Download (1.4 MB) High Blood Pressure A high blood pressure reading. copyright American Heart ...

  20. Breast Cancer Risk Prediction Models

    Cancer.gov

    Developing statistical models that estimate the probability of developing breast cancer over a defined period of time will help clinicians identify individuals at higher risk of specific cancers, allowing for earlier or more frequent screening and counseling of behavioral changes to decrease risk.

  1. Esophageal Cancer Risk Prediction Models

    Cancer.gov

    Developing statistical models that estimate the probability of developing esophageal cancer over a defined period of time will help clinicians identify individuals at higher risk of specific cancers, allowing for earlier or more frequent screening and counseling of behavioral changes to decrease risk.

  2. Colorectal Cancer Risk Prediction Models

    Cancer.gov

    Developing statistical models that estimate the probability of developing colorectal cancer over a defined period of time will help clinicians identify individuals at higher risk of specific cancers, allowing for earlier or more frequent screening and counseling of behavioral changes to decrease risk.

  3. Prostate Cancer Risk Prediction Models

    Cancer.gov

    Developing statistical models that estimate the probability of developing prostate cancer over a defined period of time will help clinicians identify individuals at higher risk of specific cancers, allowing for earlier or more frequent screening and counseling of behavioral changes to decrease risk.

  4. Pancreatic Cancer Risk Prediction Models

    Cancer.gov

    Developing statistical models that estimate the probability of developing pancreatic cancer over a defined period of time will help clinicians identify individuals at higher risk of specific cancers, allowing for earlier or more frequent screening and counseling of behavioral changes to decrease risk.

  5. Lung Cancer Risk Prediction Models

    Cancer.gov

    Developing statistical models that estimate the probability of developing lung cancer over a defined period of time will help clinicians identify individuals at higher risk of specific cancers, allowing for earlier or more frequent screening and counseling of behavioral changes to decrease risk.

  6. Testicular Cancer Risk Prediction Models

    Cancer.gov

    Developing statistical models that estimate the probability of testicular cervical cancer over a defined period of time will help clinicians identify individuals at higher risk of specific cancers, allowing for earlier or more frequent screening and counseling of behavioral changes to decrease risk.

  7. Ovarian Cancer Risk Prediction Models

    Cancer.gov

    Developing statistical models that estimate the probability of developing ovarian cancer over a defined period of time will help clinicians identify individuals at higher risk of specific cancers, allowing for earlier or more frequent screening and counseling of behavioral changes to decrease risk.

  8. Cervical Cancer Risk Prediction Models

    Cancer.gov

    Developing statistical models that estimate the probability of developing cervical cancer over a defined period of time will help clinicians identify individuals at higher risk of specific cancers, allowing for earlier or more frequent screening and counseling of behavioral changes to decrease risk.

  9. Bladder Cancer Risk Prediction Models

    Cancer.gov

    Developing statistical models that estimate the probability of developing bladder cancer over a defined period of time will help clinicians identify individuals at higher risk of specific cancers, allowing for earlier or more frequent screening and counseling of behavioral changes to decrease risk.

  10. Liver Cancer Risk Prediction Models

    Cancer.gov

    Developing statistical models that estimate the probability of developing liver cancer over a defined period of time will help clinicians identify individuals at higher risk of specific cancers, allowing for earlier or more frequent screening and counseling of behavioral changes to decrease risk.

  11. Risk modelling in portfolio optimization

    NASA Astrophysics Data System (ADS)

    Lam, W. H.; Jaaman, Saiful Hafizah Hj.; Isa, Zaidi

    2013-09-01

    Risk management is very important in portfolio optimization. The mean-variance model has been used in portfolio optimization to minimize the investment risk. The objective of the mean-variance model is to minimize the portfolio risk and achieve the target rate of return. Variance is used as risk measure in the mean-variance model. The purpose of this study is to compare the portfolio composition as well as performance between the optimal portfolio of mean-variance model and equally weighted portfolio. Equally weighted portfolio means the proportions that are invested in each asset are equal. The results show that the portfolio composition of the mean-variance optimal portfolio and equally weighted portfolio are different. Besides that, the mean-variance optimal portfolio gives better performance because it gives higher performance ratio than the equally weighted portfolio.

  12. Models for Pesticide Risk Assessment

    EPA Pesticide Factsheets

    EPA considers the toxicity of the pesticide as well as the amount of pesticide to which a person or the environments may be exposed in risk assessment. Scientists use mathematical models to predict pesticide concentrations in exposure assessment.

  13. Exercise blood pressure and the risk of future hypertension.

    PubMed

    Holmqvist, L; Mortensen, L; Kanckos, C; Ljungman, C; Mehlig, K; Manhem, K

    2012-12-01

    The aim of this prospective cohort study was to identify which blood pressure measurement during exercise is the best predictor of future hypertension. Further we aimed to create a risk chart to facilitate the evaluation of blood pressure reaction during exercise testing. A number (n=1047) of exercise tests by bicycle ergometry, performed in 1996 and 1997 were analysed. In 2007-2008, 606 patients without hypertension at the time of the exercise test were sent a questionnaire aimed to identify current hypertension. The response rate was 58% (n=352). During the 10-12 years between exercise test and questionnaire, 23% developed hypertension. The strongest predictors of future hypertension were systolic blood pressure (SBP) before exercise (odds ratios (OR) 1.63 (1.31-2.01) for 10 mm Hg difference) in combination with the increase of SBP over time during exercise testing (OR 1.12 (1.01-1.24) steeper increase for every 1 mm Hg min(-1)). A high SBP before exercise and a steep rise in SBP over time represented a higher risk of developing hypertension. A risk chart based on SBP before exercise, increase of SBP over time and body mass index was created. SBP before exercise, maximal SBP during exercise and SBP at 100 W were significant single predictors of future hypertension and the prediction by maximal SBP was improved by adjusting for time/power at which SBP max was reached during exercise testing. Recovery ratio (maximal SBP/SBP 4 min after exercise) was not predictive of future hypertension.

  14. Genome-wide association analysis identifies novel blood pressure loci and offers biological insights into cardiovascular risk.

    PubMed

    Warren, Helen R; Evangelou, Evangelos; Cabrera, Claudia P; Gao, He; Ren, Meixia; Mifsud, Borbala; Ntalla, Ioanna; Surendran, Praveen; Liu, Chunyu; Cook, James P; Kraja, Aldi T; Drenos, Fotios; Loh, Marie; Verweij, Niek; Marten, Jonathan; Karaman, Ibrahim; Lepe, Marcelo P Segura; O'Reilly, Paul F; Knight, Joanne; Snieder, Harold; Kato, Norihiro; He, Jiang; Tai, E Shyong; Said, M Abdullah; Porteous, David; Alver, Maris; Poulter, Neil; Farrall, Martin; Gansevoort, Ron T; Padmanabhan, Sandosh; Mägi, Reedik; Stanton, Alice; Connell, John; Bakker, Stephan J L; Metspalu, Andres; Shields, Denis C; Thom, Simon; Brown, Morris; Sever, Peter; Esko, Tõnu; Hayward, Caroline; van der Harst, Pim; Saleheen, Danish; Chowdhury, Rajiv; Chambers, John C; Chasman, Daniel I; Chakravarti, Aravinda; Newton-Cheh, Christopher; Lindgren, Cecilia M; Levy, Daniel; Kooner, Jaspal S; Keavney, Bernard; Tomaszewski, Maciej; Samani, Nilesh J; Howson, Joanna M M; Tobin, Martin D; Munroe, Patricia B; Ehret, Georg B; Wain, Louise V

    2017-03-01

    Elevated blood pressure is the leading heritable risk factor for cardiovascular disease worldwide. We report genetic association of blood pressure (systolic, diastolic, pulse pressure) among UK Biobank participants of European ancestry with independent replication in other cohorts, and robust validation of 107 independent loci. We also identify new independent variants at 11 previously reported blood pressure loci. In combination with results from a range of in silico functional analyses and wet bench experiments, our findings highlight new biological pathways for blood pressure regulation enriched for genes expressed in vascular tissues and identify potential therapeutic targets for hypertension. Results from genetic risk score models raise the possibility of a precision medicine approach through early lifestyle intervention to offset the impact of blood pressure-raising genetic variants on future cardiovascular disease risk.

  15. Blood pressure and cardiovascular risk: what about cocoa and chocolate?

    PubMed

    Grassi, Davide; Desideri, Giovambattista; Ferri, Claudio

    2010-09-01

    Cocoa flavonoids are able to reduce cardiovascular risk by improving endothelial function and decreasing blood pressure (BP). Interest in the biological activities of cocoa is daily increasing. A recent meta-analysis shows flavanol-rich cocoa administration decreases mean systolic (-4.5mm Hg; p<0.001) and diastolic (-2.5mm Hg; p<0.001) BP. A 3-mm Hg systolic BP reduction has been estimated to decrease the risk of cardiovascular and all-cause mortality. This paper summarizes new findings concerning cocoa effects on cardiovascular health focusing on putative mechanisms of action and nutritional and "pharmacological" viewpoints. Cocoa consumption could play a pivotal role in human health.

  16. [Using the 'Driving Force - Pressure - State - Exposure - Effects - Action' (DPSEEA) model of the World Health Organization (WHO) for the analysis of risks related to the use of pesticides in agricultural activities in the state of Rio de Janeiro].

    PubMed

    Araújo-Pinto, Mariana de; Peres, Frederico; Moreira, Josino Costa

    2012-06-01

    This paper seeks to apply the DPSEEA model (WHO) to identify major health risks to rural workers and the environment associated with the intensive use of pesticides in the State of Rio de Janeiro, based on an analysis of official public documents and a review of the (national and international) literature. It emphasizes the two main representative branches of agriculture in the state: family farming in the mountain region and the monoculture of sugarcane in the flatlands. Results show that the bulk of the determinants identified in the DPSEEA Matrix are related to deficiencies in actions for monitoring and surveillance of pesticide use, as well as a lack of technical assistance provided by the Public Sector in Rio de Janeiro State. Most of the actions developed in the state address the effects of pesticide exposure and, to a lesser extent, exposure to these chemicals, failing to focus on the higher levels of the matrix (such as driving forces and pressure). These are considered, by several authors, as the most appropriate when tackling the complex and systemic issues, such as the scope of this paper. By means of this study, an attempt was made to enable the application of the DPSEEA Model to assist in environmental and occupational health surveillance initiatives.

  17. Layzer type models for pressure driven shells

    SciTech Connect

    Hurricane, O A

    2004-09-16

    Models for the nonlinear instability of finite thickness shells driven by pressure are constructed in the style of Layzer. Equations for both Cartesian and cylindrically convergent/divergent geometries are derived. The resulting equations are appropriate for incompressible shells with unity Atwood number. Predictions from the equations compare well with two-dimensional simulations.

  18. Modeling steam pressure under martian lava flows

    USGS Publications Warehouse

    Dundas, Colin M.; Keszthelyi, Laszlo P.

    2013-01-01

    Rootless cones on Mars are a valuable indicator of past interactions between lava and water. However, the details of the lava–water interactions are not fully understood, limiting the ability to use these features to infer new information about past water on Mars. We have developed a model for the pressurization of a dry layer of porous regolith by melting and boiling ground ice in the shallow subsurface. This model builds on previous models of lava cooling and melting of subsurface ice. We find that for reasonable regolith properties and ice depths of decimeters, explosive pressures can be reached. However, the energy stored within such lags is insufficient to excavate thick flows unless they draw steam from a broader region than the local eruption site. These results indicate that lag pressurization can drive rootless cone formation under favorable circumstances, but in other instances molten fuel–coolant interactions are probably required. We use the model results to consider a range of scenarios for rootless cone formation in Athabasca Valles. Pressure buildup by melting and boiling ice under a desiccated lag is possible in some locations, consistent with the expected distribution of ice implanted from atmospheric water vapor. However, it is uncertain whether such ice has existed in the vicinity of Athabasca Valles in recent history. Plausible alternative sources include surface snow or an aqueous flood shortly before the emplacement of the lava flow.

  19. Layzer type models for pressure driven shells

    SciTech Connect

    Hurricane, O.A.

    2005-05-01

    Models for the nonlinear instability of finite thickness shells driven by pressure are constructed in the style of Layzer. Equations for both Cartesian and cylindrically convergent/divergent geometries are derived. The resulting equations are appropriate for incompressible shells with unity Atwood number. Predictions from the equations compare well with two-dimensional simulations.

  20. Pressure ulcers in palliative ward patients: hyponatremia and low blood pressure as indicators of risk

    PubMed Central

    Sternal, Danuta; Wilczyński, Krzysztof; Szewieczek, Jan

    2017-01-01

    Background Prevention strategies for pressure ulcer formation remain critical in patients with an advanced illness. We analyzed factors associated with the development of pressure ulcers in patients hospitalized in a palliative care ward setting. Patients and methods This study was a retrospective analysis of 329 consecutive patients with a mean age (± standard deviation) of 70.4±11.8 years (range: 30–96 years, median 70.0 years; 55.3% women), who were admitted to the Palliative Care Department between July 2012 and May 2014. Results Patients were hospitalized for mean of 24.8±31.4 days (1–310 days, median 14 days). A total of 256 patients (77.8%) died in the ward and 73 patients (22.2%) were discharged. Two hundred and six patients (62.6%) did not develop pressure ulcers during their stay in the ward, 84 patients (25.5%) were admitted with pressure ulcers, and 39 patients (11.9%) developed pressure ulcers in the ward. Four factors assessed at admission appear to predict the development of pressure ulcers in the multivariate logistic regression model: Waterlow score (odds ratio [OR] =1.140, 95% confidence interval [CI] =1.057–1.229, P=0.001), transfer from other hospital wards (OR =2.938, 95% CI =1.339–6.448, P=0.007), hemoglobin level (OR =0.814, 95% CI =0.693–0.956, P=0.012), and systolic blood pressure (OR =0.976, 95% CI =0.955–0.997, P=0.023). Five other factors assessed during hospitalization appear to be associated with pressure ulcer development: mean evening body temperature (OR =3.830, 95% CI =1.729–8.486, P=0.001), mean Waterlow score (OR =1.194, 95% CI =1.092–1.306, P<0.001), the lowest recorded sodium concentration (OR =0.880, 95% CI =0.814–0.951, P=0.001), mean systolic blood pressure (OR =0.956, 95% CI =0.929–0.984, P=0.003), and the lowest recorded hemoglobin level (OR =0.803, 95% CI =0.672–0.960, P=0.016). Conclusion Hyponatremia and low blood pressure may contribute to the formation of pressure ulcers in patients with an

  1. The potential for health risks from intrusion of contaminants into the distribution system from pressure transients.

    PubMed

    LeChevallier, Mark W; Gullick, Richard W; Karim, Mohammad R; Friedman, Melinda; Funk, James E

    2003-03-01

    The potential for public health risks associated with intrusion of contaminants into water supply distribution systems resulting from transient low or negative pressures is assessed. It is shown that transient pressure events occur in distribution systems; that during these negative pressure events pipeline leaks provide a potential portal for entry of groundwater into treated drinking water; and that faecal indicators and culturable human viruses are present in the soil and water exterior to the distribution system. To date, all observed negative pressure events have been related to power outages or other pump shutdowns. Although there are insufficient data to indicate whether pressure transients are a substantial source of risk to water quality in the distribution system, mitigation techniques can be implemented, principally the maintenance of an effective disinfectant residual throughout the distribution system, leak control, redesign of air relief venting, and more rigorous application of existing engineering standards. Use of high-speed pressure data loggers and surge modelling may have some merit, but more research is needed.

  2. Formation risk of toxic and other unwanted compounds in pressure-assisted thermally processed foods.

    PubMed

    Bravo, K Segovia; Ramírez, R; Durst, R; Escobedo-Avellaneda, Z J; Welti-Chanes, J; Sanz, P D; Torres, J A

    2012-01-01

    Consumers demand, in addition to excellent eating quality, high standards of microbial and chemical safety in shelf-stable foods. This requires improving conventional processing technologies and developing new alternatives such as pressure-assisted thermal processing (PATP). Studies in PATP foods on the kinetics of chemical reactions at temperatures (approximately 100 to 120 °C) inactivating bacterial spores in low-acid foods are severely lacking. This review focuses on a specific chemical safety risk in PATP foods: models predicting if the activation volume value (V(a) ) of a chemical reaction is positive or negative, and indicating if the reaction rate constant will decrease or increase with pressure, respectively, are not available. Therefore, the pressure effect on reactions producing toxic compounds must be determined experimentally. A recent model solution study showed that acrylamide formation, a potential risk in PATP foods, is actually inhibited by pressure (that is, its V(a) value must be positive). This favorable finding was not predictable and still needs to be confirmed in food systems. Similar studies are required for other reactions producing toxic compounds including polycyclic aromatic hydrocarbons, heterocyclic amines, N-nitroso compounds, and hormone like-peptides. Studies on PATP inactivation of prions, and screening methods to detect the presence of other toxicity risks of PATP foods, are also reviewed.

  3. Multidimensional Gravitational Model with Anisotropic Pressure

    NASA Astrophysics Data System (ADS)

    Grigorieva, O. A.; Sharov, G. S.

    2013-08-01

    We consider the gravitational model with additional spatial dimensions and anisotropic pressure which is nonzero only in these dimensions. Cosmological solutions of the Einstein equations in this model include accelerated expansion of the universe at late stage of its evolution and dynamical compactification of extra dimensions. This model describes observational data for Type Ia supernovae on the level or better than the ΛCDM model. We analyze two equations of state resulting in different predictions for further evolution, but in both variants the acceleration epoch is finite.

  4. Multifractal Value at Risk model

    NASA Astrophysics Data System (ADS)

    Lee, Hojin; Song, Jae Wook; Chang, Woojin

    2016-06-01

    In this paper new Value at Risk (VaR) model is proposed and investigated. We consider the multifractal property of financial time series and develop a multifractal Value at Risk (MFVaR). MFVaR introduced in this paper is analytically tractable and not based on simulation. Empirical study showed that MFVaR can provide the more stable and accurate forecasting performance in volatile financial markets where large loss can be incurred. This implies that our multifractal VaR works well for the risk measurement of extreme credit events.

  5. Communicating Health Risks under Pressure: Homeland Security Applications

    SciTech Connect

    Garrahan, K.G.; Collie, S.L.

    2006-07-01

    The U.S. Environmental Protection Agency's (EPA) Office of Research and Development (ORD) Threat and Consequence Assessment Division (TCAD) within the National Homeland Security Research Center (NHSRC) has developed a tool for rapid communication of health risks and likelihood of exposure in preparation for terrorist incidents. The Emergency Consequence Assessment Tool (ECAT) is a secure web-based tool designed to make risk assessment and consequence management faster and easier for high priority terrorist threat scenarios. ECAT has been designed to function as 'defensive play-book' for health advisors, first responders, and decision-makers by presenting a series of evaluation templates for priority scenarios that can be modified for site-specific applications. Perhaps most importantly, the risk communication aspect is considered prior to an actual release event, so that management or legal advisors can concur on general risk communication content in preparation for press releases that can be anticipated in case of an actual emergency. ECAT serves as a one-stop source of information for retrieving toxicological properties for agents of concern, estimating exposure to these agents, characterizing health risks, and determining what actions need to be undertaken to mitigate the risks. ECAT has the capability to be used at a command post where inputs can be checked and communicated while the response continues in real time. This front-end planning is intended to fill the gap most commonly identified during tabletop exercises: a need for concise, timely, and informative risk communication to all parties. Training and customization of existing chemical and biological release scenarios with modeling of exposure to air and water, along with custom risk communication 'messages' intended for public, press, shareholders, and other partners enable more effective communication during times of crisis. For DOE, the ECAT could serve as a prototype that would be amenable to

  6. Cabin Environment Physics Risk Model

    NASA Technical Reports Server (NTRS)

    Mattenberger, Christopher J.; Mathias, Donovan Leigh

    2014-01-01

    This paper presents a Cabin Environment Physics Risk (CEPR) model that predicts the time for an initial failure of Environmental Control and Life Support System (ECLSS) functionality to propagate into a hazardous environment and trigger a loss-of-crew (LOC) event. This physics-of failure model allows a probabilistic risk assessment of a crewed spacecraft to account for the cabin environment, which can serve as a buffer to protect the crew during an abort from orbit and ultimately enable a safe return. The results of the CEPR model replace the assumption that failure of the crew critical ECLSS functionality causes LOC instantly, and provide a more accurate representation of the spacecraft's risk posture. The instant-LOC assumption is shown to be excessively conservative and, moreover, can impact the relative risk drivers identified for the spacecraft. This, in turn, could lead the design team to allocate mass for equipment to reduce overly conservative risk estimates in a suboptimal configuration, which inherently increases the overall risk to the crew. For example, available mass could be poorly used to add redundant ECLSS components that have a negligible benefit but appear to make the vehicle safer due to poor assumptions about the propagation time of ECLSS failures.

  7. Information risk and security modeling

    NASA Astrophysics Data System (ADS)

    Zivic, Predrag

    2005-03-01

    This research paper presentation will feature current frameworks to addressing risk and security modeling and metrics. The paper will analyze technical level risk and security metrics of Common Criteria/ISO15408, Centre for Internet Security guidelines, NSA configuration guidelines and metrics used at this level. Information IT operational standards view on security metrics such as GMITS/ISO13335, ITIL/ITMS and architectural guidelines such as ISO7498-2 will be explained. Business process level standards such as ISO17799, COSO and CobiT will be presented with their control approach to security metrics. Top level, the maturity standards such as SSE-CMM/ISO21827, NSA Infosec Assessment and CobiT will be explored and reviewed. For each defined level of security metrics the research presentation will explore the appropriate usage of these standards. The paper will discuss standards approaches to conducting the risk and security metrics. The research findings will demonstrate the need for common baseline for both risk and security metrics. This paper will show the relation between the attribute based common baseline and corporate assets and controls for risk and security metrics. IT will be shown that such approach spans over all mentioned standards. The proposed approach 3D visual presentation and development of the Information Security Model will be analyzed and postulated. Presentation will clearly demonstrate the benefits of proposed attributes based approach and defined risk and security space for modeling and measuring.

  8. Analytic Modeling of Pressurization and Cryogenic Propellant

    NASA Technical Reports Server (NTRS)

    Corpening, Jeremy H.

    2010-01-01

    An analytic model for pressurization and cryogenic propellant conditions during all mission phases of any liquid rocket based vehicle has been developed and validated. The model assumes the propellant tanks to be divided into five nodes and also implements an empirical correlation for liquid stratification if desired. The five nodes include a tank wall node exposed to ullage gas, an ullage gas node, a saturated propellant vapor node at the liquid-vapor interface, a liquid node, and a tank wall node exposed to liquid. The conservation equations of mass and energy are then applied across all the node boundaries and, with the use of perfect gas assumptions, explicit solutions for ullage and liquid conditions are derived. All fluid properties are updated real time using NIST Refprop.1 Further, mass transfer at the liquid-vapor interface is included in the form of evaporation, bulk boiling of liquid propellant, and condensation given the appropriate conditions for each. Model validation has proven highly successful against previous analytic models and various Saturn era test data and reasonably successful against more recent LH2 tank self pressurization ground test data. Finally, this model has been applied to numerous design iterations for the Altair Lunar Lander, Ares V Core Stage, and Ares V Earth Departure Stage in order to characterize Helium and autogenous pressurant requirements, propellant lost to evaporation and thermodynamic venting to maintain propellant conditions, and non-uniform tank draining in configurations utilizing multiple LH2 or LO2 propellant tanks. In conclusion, this model provides an accurate and efficient means of analyzing multiple design configurations for any cryogenic propellant tank in launch, low-acceleration coast, or in-space maneuvering and supplies the user with pressurization requirements, unusable propellants from evaporation and liquid stratification, and general ullage gas, liquid, and tank wall conditions as functions of time.

  9. Command Process Modeling & Risk Analysis

    NASA Technical Reports Server (NTRS)

    Meshkat, Leila

    2011-01-01

    Commanding Errors may be caused by a variety of root causes. It's important to understand the relative significance of each of these causes for making institutional investment decisions. One of these causes is the lack of standardized processes and procedures for command and control. We mitigate this problem by building periodic tables and models corresponding to key functions within it. These models include simulation analysis and probabilistic risk assessment models.

  10. Lunar Landing Operational Risk Model

    NASA Technical Reports Server (NTRS)

    Mattenberger, Chris; Putney, Blake; Rust, Randy; Derkowski, Brian

    2010-01-01

    Characterizing the risk of spacecraft goes beyond simply modeling equipment reliability. Some portions of the mission require complex interactions between system elements that can lead to failure without an actual hardware fault. Landing risk is currently the least characterized aspect of the Altair lunar lander and appears to result from complex temporal interactions between pilot, sensors, surface characteristics and vehicle capabilities rather than hardware failures. The Lunar Landing Operational Risk Model (LLORM) seeks to provide rapid and flexible quantitative insight into the risks driving the landing event and to gauge sensitivities of the vehicle to changes in system configuration and mission operations. The LLORM takes a Monte Carlo based approach to estimate the operational risk of the Lunar Landing Event and calculates estimates of the risk of Loss of Mission (LOM) - Abort Required and is Successful, Loss of Crew (LOC) - Vehicle Crashes or Cannot Reach Orbit, and Success. The LLORM is meant to be used during the conceptual design phase to inform decision makers transparently of the reliability impacts of design decisions, to identify areas of the design which may require additional robustness, and to aid in the development and flow-down of requirements.

  11. Pressure Ulcers in the Hospitalized Neonate: Rates and Risk Factors

    PubMed Central

    Visscher, Marty; Taylor, Teresa

    2014-01-01

    Pressure ulcers (PU) are serious, reportable events causing pain, infection and prolonged hospitalization, particularly among critically ill patients. The literature on PUs in neonates is limited. The objective was to determine the etiology, severity and influence of gestational age on PUs among hospitalized infants. A two-year prospective study was conducted among 741 neonatal intensive care patients over 31,643 patient-days. Risk factors were determined by comparing the characteristics of infants who developed PUs with those who did not. There were 1.5 PUs per 1000 patient days with 1.0 PU per 1000 days in premature infants and 2.7 per 1000 days in term infants. The number of PUs associated with devices was nearly 80% overall and over 90% in premature infants. Infants with PUs had longer hospitalizations and weighed more than those who did not. Infants with device-related PUs were younger, of lower gestational age and developed the PU earlier than patients with PUs due to conventional pressure. The time to PU development was longer in prematurely born versus term infants. Hospitalized neonates are susceptible to device-related injury and the rate of stage II injury is high. Strategies for early detection and mitigation of device-related injury are essential to prevent PUs. PMID:25502955

  12. A Corrosion Risk Assessment Model for Underground Piping

    NASA Technical Reports Server (NTRS)

    Datta, Koushik; Fraser, Douglas R.

    2009-01-01

    The Pressure Systems Manager at NASA Ames Research Center (ARC) has embarked on a project to collect data and develop risk assessment models to support risk-informed decision making regarding future inspections of underground pipes at ARC. This paper shows progress in one area of this project - a corrosion risk assessment model for the underground high-pressure air distribution piping system at ARC. It consists of a Corrosion Model of pipe-segments, a Pipe Wrap Protection Model; and a Pipe Stress Model for a pipe segment. A Monte Carlo simulation of the combined models provides a distribution of the failure probabilities. Sensitivity study results show that the model uncertainty, or lack of knowledge, is the dominant contributor to the calculated unreliability of the underground piping system. As a result, the Pressure Systems Manager may consider investing resources specifically focused on reducing these uncertainties. Future work includes completing the data collection effort for the existing ground based pressure systems and applying the risk models to risk-based inspection strategies of the underground pipes at ARC.

  13. Pressurization Risk Assessment of CO2 Reservoirs Utilizing Design of Experiments and Response Surface Methods

    NASA Astrophysics Data System (ADS)

    Guyant, E.; Han, W. S.; Kim, K. Y.; Park, E.; Han, K.

    2015-12-01

    Monitoring of pressure buildup can provide explicit information on reservoir integrity and is an appealing tool, however pressure variation is dependent on a variety of factors causing high uncertainty in pressure predictions. This work evaluated pressurization of a reservoir system in the presence of leakage pathways as well as exploring the effects of compartmentalization of the reservoir utilizing design of experiments (Definitive Screening, Box Behnken, Central Composite, and Latin Hypercube designs) and response surface methods. Two models were developed, 1) an idealized injection scenario in order to evaluate the performance of multiple designs, and 2) a complex injection scenario implementing the best performing design to investigate pressurization of the reservoir system. A holistic evaluation of scenario 1, determined that the Central Composite design would be used for the complex injection scenario. The complex scenario evaluated 5 risk factors: reservoir, seal, leakage pathway and fault permeabilities, and horizontal position of the pathway. A total of 60 response surface models (RSM) were developed for the complex scenario with an average R2 of 0.95 and a NRMSE of 0.067. Sensitivity to the input factors was dynamic through space and time; at the earliest time (0.05 years) the reservoir permeability was dominant, and for later times (>0.5 years) the fault permeability became dominant for all locations. The RSM's were then used to conduct a Monte Carlo Analysis to further analyze pressurization risks, identifying the P10, P50, P90 values. This identified the in zone (lower) P90 values as 2.16, 1.77, and 1.53 MPa and above zone values of 1.35, 1.23, 1.09 MPa for monitoring locations 1, 2, and 3, respectively. In summary, the design of experiments and response surface methods allowed for an efficient sensitivity and uncertainty analysis to be conducted permitting a complete evaluation of the pressurization across the entire parameter space.

  14. Approach for Mitigating Pressure Garment Design Risks in a Mobile Lunar Surface Systems Architecture

    NASA Technical Reports Server (NTRS)

    Aitchison, Lindsay

    2009-01-01

    The stated goals of the 2004 Vision for Space Exploration focus on establishing a human presence throughout the solar system beginning with the establishment of a permanent human presence on the Moon. However, the precise objectives to be accomplished on the lunar surface and the optimal system architecture to achieve those objectives have been a topic of much debate since the inception of the Constellation Program. There are two basic styles of system architectures being traded at the Programmatic level: a traditional large outpost that would focus on techniques for survival off our home planet and a greater depth of exploration within one area, or a mobile approach- akin to a series of nomadic camps- that would allow greater breadth of exploration opportunities. The traditional outpost philosophy is well within the understood pressure garment design space with respect to developing interfaces and operational life cycle models. The mobile outpost, however, combines many unknowns with respect to pressure garment performance and reliability that could dramatically affect the cost and schedule risks associated with the Constellation space suit system. This paper provides an overview of the concepts being traded for a mobile architecture from the operations and hardware implementation perspective, describes the primary risks to the Constellation pressure garment associated with each of the concepts, and summarizes the approach necessary to quantify the pressure garment design risks to enable the Constellation Program to make informed decisions when deciding on an overall lunar surface systems architecture.

  15. Risk perception in epidemic modeling

    NASA Astrophysics Data System (ADS)

    Bagnoli, Franco; Liò, Pietro; Sguanci, Luca

    2007-12-01

    We investigate the effects of risk perception in a simple model of epidemic spreading. We assume that the perception of the risk of being infected depends on the fraction of neighbors that are ill. The effect of this factor is to decrease the infectivity, that therefore becomes a dynamical component of the model. We study the problem in the mean-field approximation and by numerical simulations for regular, random, and scale-free networks. We show that for homogeneous and random networks, there is always a value of perception that stops the epidemics. In the “worst-case” scenario of a scale-free network with diverging input connectivity, a linear perception cannot stop the epidemics; however, we show that a nonlinear increase of the perception risk may lead to the extinction of the disease. This transition is discontinuous, and is not predicted by the mean-field analysis.

  16. Pressure Distribution over Thick Airfoils - Model Tests

    NASA Technical Reports Server (NTRS)

    Norton, F H; Bacon, D L

    1923-01-01

    This investigation was undertaken to study the distribution of loading over thick wings of various types. The unloading on the wing was determined by taking the pressure at a number of holes on both the upper and lower surfaces of a model wing in the wind tunnel. The results from these tests show, first, that the distribution of pressure over a thick wing of uniform section is very little different from that over a thin wing; second, that wings tapering either in chord or thickness have the lateral center of pressure, as would be expected, slightly nearer the center of the wings; and, third, that wings tapering in plan form and with a section everywhere proportional to the center section may be considered to have a loading at any point which is proportional to the chord when compared to a wing with a similar constant section. These tests confirm the belief that wings tapering both in thickness and plan form are of considerable structural value because the lateral center of pressure is thereby moved toward the center of the span.

  17. Become the PPUPET Master: Mastering Pressure Ulcer Risk Assessment With the Pediatric Pressure Ulcer Prediction and Evaluation Tool (PPUPET).

    PubMed

    Sterken, David J; Mooney, JoAnn; Ropele, Diana; Kett, Alysha; Vander Laan, Karen J

    2015-01-01

    Hospital acquired pressure ulcers (HAPU) are serious, debilitating, and preventable complications in all inpatient populations. Despite evidence of the development of pressure ulcers in the pediatric population, minimal research has been done. Based on observations gathered during quarterly HAPU audits, bedside nursing staff recognized trends in pressure ulcer locations that were not captured using current pressure ulcer risk assessment tools. Together, bedside nurses and nursing leadership created and conducted multiple research studies to investigate the validity and reliability of the Pediatric Pressure Ulcer Prediction and Evaluation Tool (PPUPET).

  18. Pressure ulcers in the intensive care unit: the relationship between nursing workload, illness severity and pressure ulcer risk.

    PubMed

    Cremasco, Mariana F; Wenzel, Fernanda; Zanei, Suely S V; Whitaker, Iveth Y

    2013-08-01

    Aims and objective.  To verify association between PU development with nursing workload and illness severity and to verify whether nursing workload and illness severity are related with Braden Scale scores. Background.  Critically ill patients are more susceptible to treatment complications because of the severity of their clinical condition. Design.  Prospective descriptive study. Methods.  Patients consecutively admitted to three intensive care units (ICUs) of a public university hospital located in Sao Paulo, Brazil and without pressure ulcer (PU) at admission and a minimum stay of 24 hours were included in the sample. Prospective data collection included demographic, clinical and hospitalisation data, Nursing Activities Score (NAS), Simplified Acute Physiology Score (SAPSII) and Braden Scale. Multivariate linear regression analysis was applied to verify whether nursing workload and illness severity are related with Braden Scale scores. Multivariate logistic regression analysis was used to verify whether nursing workload and illness severity were risk factors associated with PU development. Results.  The study sample included 160 patients. The mean Braden score was 12·0 and PU incidence was 34·4%. Multivariate linear regression analysis identified as factors related to variation of Braden scores: illness severity (SAPSII), nursing workload (NAS) and age. Multivariate logistic regression showed a model with risk factors associated with PU development: sex, length of ICU stay, illness severity and nursing workload. Conclusion.  Nursing workload, severity of illness, sex and length of ICU stay were identified as risk factors associated with PU development. However, nursing workload acted as a protective factor. Illness severity, nursing workload and age were related to Braden scores. Relevance to clinical practice.  Accurate identification of risk factors and the use of clinical judgment in skin assessment are prerequisites for determining

  19. Quantile uncertainty and value-at-risk model risk.

    PubMed

    Alexander, Carol; Sarabia, José María

    2012-08-01

    This article develops a methodology for quantifying model risk in quantile risk estimates. The application of quantile estimates to risk assessment has become common practice in many disciplines, including hydrology, climate change, statistical process control, insurance and actuarial science, and the uncertainty surrounding these estimates has long been recognized. Our work is particularly important in finance, where quantile estimates (called Value-at-Risk) have been the cornerstone of banking risk management since the mid 1980s. A recent amendment to the Basel II Accord recommends additional market risk capital to cover all sources of "model risk" in the estimation of these quantiles. We provide a novel and elegant framework whereby quantile estimates are adjusted for model risk, relative to a benchmark which represents the state of knowledge of the authority that is responsible for model risk. A simulation experiment in which the degree of model risk is controlled illustrates how to quantify Value-at-Risk model risk and compute the required regulatory capital add-on for banks. An empirical example based on real data shows how the methodology can be put into practice, using only two time series (daily Value-at-Risk and daily profit and loss) from a large bank. We conclude with a discussion of potential applications to nonfinancial risks.

  20. New high blood pressure guidelines create new at-risk classification: changes in blood pressure classification by JNC 7.

    PubMed

    Miller, Edgar R; Jehn, Megan L

    2004-01-01

    High blood pressure has become increasingly prevalent and is an important risk factor for cardiovascular disease. The Seventh Report of the Joint National Committee on the Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7) has redefined normal blood pressure as less than 120/80 mm Hg and created a new blood pressure category called "prehypertension" for those with a systolic BP of 120 to 139 mm Hg or a diastolic BP of 80 to 89 mm Hg. This new blood pressure category was created to identify adults considered to be at risk for developing hypertension and to alert both patients and healthcare providers of the importance of adopting lifestyle changes. Recognition of prehypertension provides important opportunities to prevent hypertension and cardiovascular disease.

  1. A Study of the Factors Associated with Risk for Development of Pressure Ulcers: A Longitudinal Analysis

    PubMed Central

    Thomas, Elizebeth; Vinodkumar, Sudhaya; Mathew, Silvia; Setia, Maninder Singh

    2015-01-01

    Background: Pressure ulcers (PUs) are prevalent in hospitalized patients; they may cause clinical, psychological, and economic problems in these patients. Previous studies are cross-sectional, have used pooled data, or cox-regression models to assess the risk for developing PU. However, PU risk scores change over time and models that account for time varying variables are useful for cohort analysis of data. Aims and Objectives: The present longitudinal study was conducted to compare the risk of PU between surgical and nonsurgical patients, and to evaluate the factors associated with the development of these ulcers over a period of time. Materials and Methods: We evaluated 290 hospitalized patients over a 4 months period. The main outcomes for our analysis were: (1) Score on the pressure risk assessment scale; and (2) the proportion of individuals who were at severe risk for developing PUs. We used random effects models for longitudinal analysis of the data. Results: The mean PU score was significantly higher in the nonsurgical patients compared with surgical patients at baseline (15.23 [3.86] vs. 9.33 [4.57]; P < 0.01). About 7% of the total patients had a score of >20 at baseline and were considered as being at high-risk for PU; the proportion was significantly higher among the nonsurgical patients compared with the surgical patients (14% vs. 4%, P = 0.003). In the adjusted models, there was no difference for severe risk for PU between surgical and nonsurgical patients (odds ratios [ORs]: 0.37, 95% confidence interval [CI]: 0.01–12.80). An additional day in the ward was associated with a significantly higher likelihood of being at high-risk for PU (OR: 1.47, 95% CI: 1.16–1.86). Conclusion: There were no significant differences between patients who were admitted for surgery compared with those who were not. An additional day in the ward, however, is important for developing a high-risk score for PU on the monitoring scale, and these patients require active

  2. Strict blood pressure control associates with decreased mortality risk by APOL1 genotype.

    PubMed

    Ku, Elaine; Lipkowitz, Michael S; Appel, Lawrence J; Parsa, Afshin; Gassman, Jennifer; Glidden, David V; Smogorzewski, Miroslaw; Hsu, Chi-Yuan

    2017-02-01

    Although APOL1 high-risk genotype partially accounts for the increased susceptibility of blacks to chronic kidney disease (CKD), whether APOL1 associates differentially with mortality risk remains controversial. Here we evaluate the association between APOL1 genotype and risk of death and determine whether APOL1 status modifies the association between strict versus usual blood pressure control and mortality risk. We performed a retrospective analysis of the African American Study of Kidney Disease and Hypertension trial that randomized black participants with CKD to strict versus usual blood pressure control from 1995 to 2001. This included 682 participants with known APOL1 genotype (157 with high-risk genotype) previously assigned to either strict (mean arterial pressure [MAP] 92 mm Hg or less) versus usual blood pressure control (MAP 102-107 mm Hg) during the trial. During a median follow-up of 14.5 years, risk of death did not differ between individuals with high- versus low-risk APOL1 genotypes (unadjusted hazard ratio 1.00 [95% confidence interval 0.76-1.33]). However, a significant interaction was detected between the APOL1 risk group and blood pressure control strategy. In the APOL1 high-risk group, the risk of death was 42% lower comparing strict versus usual blood pressure control (0.58 [0.35-0.97]). In the APOL1 low-risk group, the risk of death comparing strict versus usual blood pressure control was not significantly different (1.09 [0.84-1.43]). Thus, strict blood pressure control during CKD associates with a lower risk of death in blacks with the high-risk CKD APOL1 genotype. Knowledge of APOL1 status could inform selection of blood pressure treatment targets in black CKD patients.

  3. Intelligent adversary risk analysis: a bioterrorism risk management model.

    PubMed

    Parnell, Gregory S; Smith, Christopher M; Moxley, Frederick I

    2010-01-01

    The tragic events of 9/11 and the concerns about the potential for a terrorist or hostile state attack with weapons of mass destruction have led to an increased emphasis on risk analysis for homeland security. Uncertain hazards (natural and engineering) have been successfully analyzed using probabilistic risk analysis (PRA). Unlike uncertain hazards, terrorists and hostile states are intelligent adversaries who can observe our vulnerabilities and dynamically adapt their plans and actions to achieve their objectives. This article compares uncertain hazard risk analysis with intelligent adversary risk analysis, describes the intelligent adversary risk analysis challenges, and presents a probabilistic defender-attacker-defender model to evaluate the baseline risk and the potential risk reduction provided by defender investments. The model includes defender decisions prior to an attack; attacker decisions during the attack; defender actions after an attack; and the uncertainties of attack implementation, detection, and consequences. The risk management model is demonstrated with an illustrative bioterrorism problem with notional data.

  4. Nursing Home Work Environment and the Risk of Pressure Ulcers and Incontinence

    PubMed Central

    Temkin-Greener, Helena; Cai, Shubing; Zheng, Nan Tracy; Zhao, Hongwei; Mukamel, Dana B

    2012-01-01

    Objective To examine the association between nursing home (NH) work environment attributes such as teams, consistent assignment and staff cohesion, and the risk of pressure ulcers and incontinence. Data Sources/Setting Minimum dataset for 46,044 residents in 162 facilities in New York State, for June 2006–July 2007, and survey responses from 7,418 workers in the same facilities. Study Design For each individual and facility, primary and secondary data were linked. Random effects logistic models were used to develop/validate outcome measures. Generalized estimating equation models with robust standard errors and probability weights were employed to examine the association between outcomes and work environment attributes. Key independent variables were staff cohesion, percent staff in daily care teams, and percent staff with consistent assignment. Other facility factors were also included. Principal Findings Residents in facilities with worse staff cohesion had significantly greater odds of pressure ulcers and incontinence, compared with residents in facilities with better cohesion scores. Residents in facilities with greater penetration of self-managed teams had lower risk of pressure ulcers, but not of incontinence. Prevalence of consistent assignment was not significantly associated with the outcome measures. Conclusions NH environments and management practices influence residents’ health outcomes. These findings provide important lessons for administrators and regulators interested in promoting NH quality improvement. PMID:22098384

  5. Genetic predisposition to higher blood pressure increases risk of incident hypertension and cardiovascular diseases in Chinese.

    PubMed

    Lu, Xiangfeng; Huang, Jianfeng; Wang, Laiyuan; Chen, Shufeng; Yang, Xueli; Li, Jianxin; Cao, Jie; Chen, Jichun; Li, Ying; Zhao, Liancheng; Li, Hongfan; Liu, Fangcao; Huang, Chen; Shen, Chong; Shen, Jinjin; Yu, Ling; Xu, Lihua; Mu, Jianjun; Wu, Xianping; Ji, Xu; Guo, Dongshuang; Zhou, Zhengyuan; Yang, Zili; Wang, Renping; Yang, Jun; Yan, Weili; Gu, Dongfeng

    2015-10-01

    Although multiple genetic markers associated with blood pressure have been identified by genome-wide association studies, their aggregate effect on risk of incident hypertension and cardiovascular disease is uncertain, particularly among East Asian who may have different genetic and environmental exposures from Europeans. We aimed to examine the association between genetic predisposition to higher blood pressure and risk of incident hypertension and cardiovascular disease in 26 262 individuals in 2 Chinese population-based prospective cohorts. A genetic risk score was calculated based on 22 established variants for blood pressure in East Asian. We found the genetic risk score was significantly and independently associated with linear increases in blood pressure and risk of incident hypertension and cardiovascular disease (P range from 4.57×10(-3) to 3.10×10(-6)). In analyses adjusted for traditional risk factors including blood pressure, individuals carrying most blood pressure-related risk alleles (top quintile of genetic score distribution) had 40% (95% confidence interval, 18-66) and 26% (6-45) increased risk for incident hypertension and cardiovascular disease, respectively, when compared with individuals in the bottom quintile. The genetic risk score also significantly improved discrimination for incident hypertension and cardiovascular disease and led to modest improvements in risk reclassification for cardiovascular disease (all the P<0.05). Our data indicate that genetic predisposition to higher blood pressure is an independent risk factor for blood pressure increase and incident hypertension and cardiovascular disease and provides modest incremental information to cardiovascular disease risk prediction. The potential clinical use of this panel of blood pressure-associated polymorphisms remains to be determined.

  6. A Quantitative Software Risk Assessment Model

    NASA Technical Reports Server (NTRS)

    Lee, Alice

    2002-01-01

    This slide presentation reviews a risk assessment model as applied to software development. the presentation uses graphs to demonstrate basic concepts of software reliability. It also discusses the application to the risk model to the software development life cycle.

  7. Thermal Modelling In Pressure Die Casting

    NASA Astrophysics Data System (ADS)

    Rasgado, M. T. Alonso; Davey, K.; Watari, H.

    2004-06-01

    The pressure die casting process is cyclic and the temperature levels in the die are principally dictated by the total energy received from the casting. It is thus extremely important that any solidification model for the casting is able to predict energy extraction rates to a high degree of accuracy. In this paper an efficient three dimensional hybrid thermal model for the pressure die casting process is described. The finite element method (FEM) is used for modelling heat transfer in the casting, coupled to a boundary element (BE) model for the die. The FEM can efficiently account for the non-linearity introduced by the release of latent heat on solidification, whereas the BEM is ideally suited for modelling linear heat conduction in the die, as surface temperatures are of principal importance. The FE formulation for the casting is based on a control volume capacitance method, which is shown to provide high accuracy and stability. This method is similar to the apparent and effective heat capacitance methods, which are popular approaches used where conduction predominates over other heat transfer mechanisms. These methods involve the specification of element or nodal capacitances to accommodate for the release of latent heat. Unfortunately they suffer from a major drawback in that energy is not correctly transported through elements and so providing a source of inaccuracy. The control volume capacitance method allows for the transport of mass arising from volumetric shrinkage and ensures that energy is correctly transported. The BE model caters for surface phenomena such as boiling in the cooling channels, which is important, as this effectively controls the manner in which energy is extracted. The die temperature is decomposed into two components, one a steady-state part and the other a time-dependent perturbation. This approach enables the transient die temperatures to be calculated in an efficient way, since only die surfaces close to the die cavity are

  8. NGNP Risk Management Database: A Model for Managing Risk

    SciTech Connect

    John Collins; John M. Beck

    2011-11-01

    The Next Generation Nuclear Plant (NGNP) Risk Management System (RMS) is a database used to maintain the project risk register. The RMS also maps risk reduction activities to specific identified risks. Further functionality of the RMS includes mapping reactor suppliers Design Data Needs (DDNs) to risk reduction tasks and mapping Phenomena Identification Ranking Table (PIRTs) to associated risks. This document outlines the basic instructions on how to use the RMS. This document constitutes Revision 1 of the NGNP Risk Management Database: A Model for Managing Risk. It incorporates the latest enhancements to the RMS. The enhancements include six new custom views of risk data - Impact/Consequence, Tasks by Project Phase, Tasks by Status, Tasks by Project Phase/Status, Tasks by Impact/WBS, and Tasks by Phase/Impact/WBS.

  9. Animal Models in Pressure Ulcer Research

    PubMed Central

    Salcido, Richard; Popescu, Adrian; Ahn, Chulhyun

    2007-01-01

    Background/Objective: Research targeting the pathophysiology, prevention, and treatment of pressure ulcers (PrUs) continue to be a significant priority for clinical and basic science research. Spinal cord injury patients particularly benefit from PrU research, because the prevalence of chronic wounds in this category is increasing despite standardized medical care. Because of practical, ethical, and safety considerations, PrUs in the human environment are limited to studies involving patients with pre-existing ulcers. Therefore, we are limited in our basic knowledge pertaining to the development, progression, and healing environment in this devastating disease. Methods: This review provides a synopsis of literature and a discussion of techniques used to induce PrUs in animal models. The question of what animal model best mimics the human PrU environment has been a subject of debate by investigators, peer review panels, and editors. The similarities in wound development and healing in mammalian tissue make murine models a relevant model for understanding the causal factors as well as the wound healing elements. Although we are beginning to understand some of the mechanisms of PrU development, a key dilemma of what makes an apparently healthy tissue develop a PrU waits to be solved. Results and Conclusions: No single method of induction and exploring PrUs in animals can address all the aspects of the pathology of chronic wounds. Each model has its particular strengths and weaknesses. Certain types of models can selectively identify specific aspects of wound development, quantify the extent of lesions, and assess outcomes from interventions. The appropriate interpretation of these methods is significant for proper study design, an understanding of the results, and extrapolation to clinical relevance. PMID:17591222

  10. Model of current enhancement at high pressure

    SciTech Connect

    Yu, S.S.; Melendez, R.E.

    1983-04-05

    A model is proposed to account for the phenomenon of net current enhancement at high pressures recently observed on the Experimental Test Accelerator. The proposed mechanism involves energetic secondary electrons (delta rays) which are pushed forward by the self-magnetic field of the electron beam. For high current beams, the forward delta ray current can build up to a significant fraction of the beam current. Analytic calculations of the steady-state solution as well as the rate of buildup of the delta ray current are presented in this paper. In addition, numerical results from a nonlocal Boltzmann code, NUTS, are presented. The analytic and numerical results have many features which are in qualitative agreement with the experiments, but quantitative discrepancies still exist.

  11. Modeling the Extreme-Pressure Lubricating Interface

    NASA Astrophysics Data System (ADS)

    Kaltchev, Matey; Gao, Feng; Lara-Romero, Javier; Tysoe, Wilfred

    2005-04-01

    Extreme-pressure lubricants are currently widely used in various areas of applications. However, despite of their common use, the fundamental aspects of the mechanism in which these lubricants reduce the friction coefficient are not clear yet. Earlier macrotribological experiments using chlorinated hydrocarbons have shown remarkable effectiveness. It has been proven that thin films that resemble those formed under tribological conditions can also be synthesized in ultrahigh vacuum when beams of chlorinated hydrocarbons are directed onto a clean iron surface. Here results obtained using X-ray photoelectron spectroscopy, temperature programmed desorption, atomic force microscopy and microtribological measurements of these films are presented. Substantial information about the fundamental properties and structure of this model lubricating interface is revealed. A mechanism of the formation of the interface under tribological conditions is also suggested.

  12. Fluid dynamic modelling of renal pelvic pressure during endoscopic stone removal

    NASA Astrophysics Data System (ADS)

    Oratis, Alexandros; Subasic, John; Bird, James; Eisner, Brian

    2015-11-01

    Endoscopic kidney stone removal procedures are known to increase internal pressure in the renal pelvis, the kidney's urinary collecting system. High renal pelvic pressure incites systemic absorption of irrigation fluid, which can increase the risk of postoperative fever and sepsis or the unwanted absorption of electrolytes. Urologists choose the appropriate surgical procedure based on patient history and kidney stone size. However, no study has been conducted to compare the pressure profiles of each procedure, nor is there a precise sense of how the renal pelvic pressure scales with various operational parameters. Here we develop physical models for the flow rates and renal pelvic pressure for various procedures. We show that the results of our models are consistent with existing urological data on each procedure and that the models can predict pressure profiles where data is unavailable.

  13. Drivers of extinction risk in African mammals: the interplay of distribution state, human pressure, conservation response and species biology

    PubMed Central

    Di Marco, Moreno; Buchanan, Graeme M.; Szantoi, Zoltan; Holmgren, Milena; Grottolo Marasini, Gabriele; Gross, Dorit; Tranquilli, Sandra; Boitani, Luigi; Rondinini, Carlo

    2014-01-01

    Although conservation intervention has reversed the decline of some species, our success is outweighed by a much larger number of species moving towards extinction. Extinction risk modelling can identify correlates of risk and species not yet recognized to be threatened. Here, we use machine learning models to identify correlates of extinction risk in African terrestrial mammals using a set of variables belonging to four classes: species distribution state, human pressures, conservation response and species biology. We derived information on distribution state and human pressure from satellite-borne imagery. Variables in all four classes were identified as important predictors of extinction risk, and interactions were observed among variables in different classes (e.g. level of protection, human threats, species distribution ranges). Species biology had a key role in mediating the effect of external variables. The model was 90% accurate in classifying extinction risk status of species, but in a few cases the observed and modelled extinction risk mismatched. Species in this condition might suffer from an incorrect classification of extinction risk (hence require reassessment). An increased availability of satellite imagery combined with improved resolution and classification accuracy of the resulting maps will play a progressively greater role in conservation monitoring. PMID:24733953

  14. Predictive Validity of Pressure Ulcer Risk Assessment Tools for Elderly: A Meta-Analysis.

    PubMed

    Park, Seong-Hi; Lee, Young-Shin; Kwon, Young-Mi

    2016-04-01

    Preventing pressure ulcers is one of the most challenging goals existing for today's health care provider. Currently used tools which assess risk of pressure ulcer development rarely evaluate the accuracy of predictability, especially in older adults. The current study aimed at providing a systemic review and meta-analysis of 29 studies using three pressure ulcer risk assessment tools: Braden, Norton, and Waterlow Scales. Overall predictive validities of pressure ulcer risks in the pooled sensitivity and specificity indicated a similar range with a moderate accuracy level in all three scales, while heterogeneity showed more than 80% variability among studies. The studies applying the Braden Scale used five different cut-off points representing the primary cause of heterogeneity. Results indicate that commonly used screening tools for pressure ulcer risk have limitations regarding validity and accuracy for use with older adults due to heterogeneity among studies.

  15. Predictive capacity of risk assessment scales and clinical judgment for pressure ulcers: a meta-analysis.

    PubMed

    García-Fernández, Francisco Pedro; Pancorbo-Hidalgo, Pedro L; Agreda, J Javier Soldevilla

    2014-01-01

    A systematic review with meta-analysis was completed to determine the capacity of risk assessment scales and nurses' clinical judgment to predict pressure ulcer (PU) development. Electronic databases were searched for prospective studies on the validity and predictive capacity of PUs risk assessment scales published between 1962 and 2010 in English, Spanish, Portuguese, Korean, German, and Greek. We excluded gray literature sources, integrative review articles, and retrospective or cross-sectional studies. The methodological quality of the studies was assessed according to the guidelines of the Critical Appraisal Skills Program. Predictive capacity was measured as relative risk (RR) with 95% confidence intervals. When 2 or more valid original studies were found, a meta-analysis was conducted using a random-effect model and sensitivity analysis. We identified 57 studies, including 31 that included a validation study. We also retrieved 4 studies that tested clinical judgment as a risk prediction factor. Meta-analysis produced the following pooled predictive capacity indicators: Braden (RR = 4.26); Norton (RR = 3.69); Waterlow (RR = 2.66); Cubbin-Jackson (RR = 8.63); EMINA (RR = 6.17); Pressure Sore Predictor Scale (RR = 21.4); and clinical judgment (RR = 1.89). Pooled analysis of 11 studies found adequate risk prediction capacity in various clinical settings; the Braden, Norton, EMINA (mEntal state, Mobility, Incontinence, Nutrition, Activity), Waterlow, and Cubbin-Jackson scales showed the highest predictive capacity. The clinical judgment of nurses was found to achieve inadequate predictive capacity when used alone, and should be used in combination with a validated scale.

  16. High Blood Pressure, Afib and Your Risk of Stroke

    MedlinePlus

    ... irregular atrial heart rhythm — a condition called atrial fibrillation — is present in about one out of five ... blood pressure is the chief culprit, and atrial fibrillation isn’t far behind. Yet there’s good news — ...

  17. Intraoperative testing of opening and closing pressure predicts risk of low intraocular pressure after Ahmed glaucoma valve implantation

    PubMed Central

    Bochmann, F; Kipfer, A; Tarantino, J; Kaufmann, C; Bachmann, L; Thiel, M

    2014-01-01

    Purpose The aim of this study was to assess whether intraoperative testing of silicone Ahmed glaucoma valves (AGVs) would identify valves with an increased risk of low postoperative intraocular pressure (IOP). Methods In 30 consecutive cases of glaucoma surgery with AGV implantation, after priming the AGV, we intraoperatively measured the opening pressure A, closing pressure B, and re-opening pressure C using the active infusion pump of a phako-machine. IOP was checked postoperatively on the same day. Low IOP was defined as <5 mm Hg. Intraoperatively measured pressure characteristics of the valve function were analysed for their ability to predict postoperative IOP outcomes. Results Opening A, closing B, and re-opening C pressures (mean, (SD)) were 18.4 (5.1), 8.3 (4.7), and 11.7 (4.8)mm Hg, respectively. Ten patients (33.3%) had low IOP. An opening pressure of ≤18 mm Hg predicted low postoperative IOP with a sensitivity (10/10) of 100% (95% CI, 69.2–100) and a specificity (13/20) of 65.0% (95% CI, 40.8–84.6). Conclusions AGVs have a high variability of opening, closing, and re-opening pressures. An opening pressure of ≤18 mm Hg, a closing pressure of ≤10 mm Hg, or a re-opening pressure of ≤11 mm Hg identified all patients with low postoperative IOP. PMID:25060848

  18. Common carotid intima-media thickness measurements do not improve cardiovascular risk prediction in individuals with elevated blood pressure: the USE-IMT collaboration.

    PubMed

    Bots, Michiel L; Groenewegen, Karlijn A; Anderson, Todd J; Britton, Annie R; Dekker, Jacqueline M; Engström, Gunnar; Evans, Greg W; de Graaf, Jacqueline; Grobbee, Diederick E; Hedblad, Bo; Hofman, Albert; Holewijn, Suzanne; Ikeda, Ai; Kavousi, Maryam; Kitagawa, Kazuo; Kitamura, Akihiko; Ikram, M Arfan; Lonn, Eva M; Lorenz, Matthias W; Mathiesen, Ellisiv B; Nijpels, Giel; Okazaki, Shuhei; O'Leary, Daniel H; Polak, Joseph F; Price, Jacqueline F; Robertson, Christine; Rembold, Christopher M; Rosvall, Maria; Rundek, Tatjana; Salonen, Jukka T; Sitzer, Matthias; Stehouwer, Coen D A; Franco, Oscar H; Peters, Sanne A E; den Ruijter, Hester M

    2014-06-01

    Carotid intima-media thickness (CIMT) is a marker of cardiovascular risk. It is unclear whether measurement of mean common CIMT improves 10-year risk prediction of first-time myocardial infarction or stroke in individuals with elevated blood pressure. We performed an analysis among individuals with elevated blood pressure (i.e., a systolic blood pressure ≥140 mm Hg and a diastolic blood pressure ≥ 90 mm Hg) in USE-IMT, a large ongoing individual participant data meta-analysis. We refitted the risk factors of the Framingham Risk Score on asymptomatic individuals (baseline model) and expanded this model with mean common CIMT (CIMT model) measurements. From both models, 10-year risks to develop a myocardial infarction or stroke were estimated. In individuals with elevated blood pressure, we compared discrimination and calibration of the 2 models and calculated the net reclassification improvement (NRI). We included 17 254 individuals with elevated blood pressure from 16 studies. During a median follow-up of 9.9 years, 2014 first-time myocardial infarctions or strokes occurred. The C-statistics of the baseline and CIMT models were similar (0.73). NRI with the addition of mean common CIMT was small and not significant (1.4%; 95% confidence intervals, -1.1 to 3.7). In those at intermediate risk (n=5008, 10-year absolute risk of 10% to 20%), the NRI was 5.6% (95% confidence intervals, 1.6-10.4). There is no added value of measurement of mean common CIMT in individuals with elevated blood pressure for improving cardiovascular risk prediction. For those at intermediate risk, the addition of mean common CIMT to an existing cardiovascular risk score is small but statistically significant.

  19. Relationship between blood lead levels and blood pressure and its cardiovascular risk implications

    SciTech Connect

    Pirkle, J.L.; Schwartz, J.; Landis, J.R.; Harlan, W.R.

    1985-02-01

    The relationship between blood pressure and blood lead levels in the second National Health and Nutrition Examination Survey (1976-1980) has been examined for white males aged 40-59 years. After adjustment for age, body mass index, nutritional factors, and blood biochemistries in a multiple linear regression model, the relationship of systolic and diastolic blood pressures to blood lead levels was statistically significant (p < 0.01). There was no evidence of a threshold blood lead level for this relationship. Although these data alone do not prove a causal relationship between low blood lead levels and blood pressure, the findings are consistent with current epidemiologic and animal studies, indicating that a causal reationship is probable. To examine the potential health risks, the multiple logistic risk factor coefficients from the Pooling Project and Framingham studies were used to predict the impact of the 37% decrease in mean blood lead levels which occurred in adult white males from 1976 to 1980. As a result of this blood lead decrease, the calculations predicted a 4.7% decrease in the incidence of fatal and nonfatal myocardial infarction over 10 years, a 6.7% decrease in the incidence of fatal and nonfatal strokes over 10 years, and a 5.5% decrease in the incidence of death from all causes over 11.5 years. In addition, as a result of this blood lead decrease, the predicted number of white males in this age group with hypertension (diastolic blood pressure greater than or equal to 90 mmHg) decreased by 17.5%.

  20. Behavior modification in primary care: the pressure system model.

    PubMed

    Katz, D L

    2001-01-01

    The leading causes of death in the United States are predominantly attributable to modifiable behaviors. Patients with behavioral risk factors for premature death and disability, including dietary practices; sexual practices; level of physical activity; motor vehi cle use patterns; and tobacco, alcohol, and illicit sub stance use, are seen far more consistently by primary care providers than by mental health specialists. Yet models of behavior modification are reported, debated, and revised almost exclusively in the psychology literature. While the Stages of Change Model, or Transtheo retical Model, has won application in a broadening array of clinical settings, its application in the primary care setting is apparently quite limited despite evidence of its utility [Prochaska J, Velicer W. Am J Health Promot 1997;12:38-48]. The lack of a rigorous behavioral model developed for application in the primary care setting is an impediment to the accomplishment of public health goals specified in the Healthy People objectives and in the reports of the U.S. Preventive Services Task Force. The Pressure System Model reported here synthesizes elements of established behavior modification theories for specific application under the constraints of the primary care setting. Use of the model in both clinical and research settings, with outcome evaluation, is encouraged as part of an effort to advance public health.

  1. Reswick and Rogers pressure-time curve for pressure ulcer risk. Part 2.

    PubMed

    Gefen, A

    In part one of this article, the concepts of an injury threshold were explained and it was shown that the Reswick and Rogers pressure-time curve is inaccurate at the extremes of the timescale. It was also shown that their curve cannot be used for studying deep tissue injuries, and that it is likely to be irrelevant for studying most pressure ulcers. The second part of this article describes recent research work focusing on tissue injury thresholds as related to pressure ulcers, with particular emphasis on thresholds that are specific for deep tissue injuries. Clinical implications are also discussed, with particular reference to patients who are obese and those with muscle atrophy.

  2. Risks assessment of water pollution by pesticides at local scale (PESTEAUX project): study of polluting pressure.

    PubMed

    Noel, Stéphanie; Billo Bah, Boubacar

    2009-01-01

    Pollution of water resources (surface waters and ground waters) by pesticide uses is one of the key point of the European policy with the implementation of the Water Frame Work Directive (2000/60/EC) and the thematic Strategy on the Sustainable use of pesticides. According to this legislation, the Member States must initiate measures to limit environmental and toxicological effects caused by pesticide uses. The Agricultural Research Centre of Wallonia (CRA-W) emphasized the need of a tool for spatial risk analysis and develOPs it within the framework of PESTEAUX project. The originality of the approach proposed by the CRA-W is to generate maps to identify the risk of pollution at locale scale (agricultural parcel). The risk will be assessed according to the study of different factors, grouped under 3 data's layers: polluting pressure, vulnerability of the physical environment (soil) and meteorological data. This approach is directly based on the risk's definition which takes into account the polluting pressure, linked to the human activities, and the vulnerability of the soil, defined by factors of physical environment which characterize the water flow in the parcel. Moreover, meteorological data influence the intensity and likelihood flow of water, and indirectly pesticide by leaching or runoff. The PESTEAUX's approach to study the pollution is based on the model "source-vector-target". The source is the polluting pressure, in other words, the pesticides which could reach the targets. The main vector is the water which vehicles the pesticide on and trough the soil until the target which are the surface waters or ground waters. In this paper we introduce the factors contributing to the polluting pressure. These factors are linking to the human activities and more precisely, to the pesticide uses. The factors considered have an influence on pesticide's transport by water (in its solid state or in dissolved state by leaching, run-off, or erosion) but also on a set of

  3. Modeling Research Project Risks with Fuzzy Maps

    ERIC Educational Resources Information Center

    Bodea, Constanta Nicoleta; Dascalu, Mariana Iuliana

    2009-01-01

    The authors propose a risks evaluation model for research projects. The model is based on fuzzy inference. The knowledge base for fuzzy process is built with a causal and cognitive map of risks. The map was especially developed for research projects, taken into account their typical lifecycle. The model was applied to an e-testing research…

  4. Pressure Sensitive Paint Applied to Flexible Models Project

    NASA Technical Reports Server (NTRS)

    Schairer, Edward T.; Kushner, Laura Kathryn

    2014-01-01

    One gap in current pressure-measurement technology is a high-spatial-resolution method for accurately measuring pressures on spatially and temporally varying wind-tunnel models such as Inflatable Aerodynamic Decelerators (IADs), parachutes, and sails. Conventional pressure taps only provide sparse measurements at discrete points and are difficult to integrate with the model structure without altering structural properties. Pressure Sensitive Paint (PSP) provides pressure measurements with high spatial resolution, but its use has been limited to rigid or semi-rigid models. Extending the use of PSP from rigid surfaces to flexible surfaces would allow direct, high-spatial-resolution measurements of the unsteady surface pressure distribution. Once developed, this new capability will be combined with existing stereo photogrammetry methods to simultaneously measure the shape of a dynamically deforming model in a wind tunnel. Presented here are the results and methodology for using PSP on flexible surfaces.

  5. Risk Models to Predict Hypertension: A Systematic Review

    PubMed Central

    Echouffo-Tcheugui, Justin B.; Batty, G. David; Kivimäki, Mika; Kengne, Andre P.

    2013-01-01

    Background As well as being a risk factor for cardiovascular disease, hypertension is also a health condition in its own right. Risk prediction models may be of value in identifying those individuals at risk of developing hypertension who are likely to benefit most from interventions. Methods and Findings To synthesize existing evidence on the performance of these models, we searched MEDLINE and EMBASE; examined bibliographies of retrieved articles; contacted experts in the field; and searched our own files. Dual review of identified studies was conducted. Included studies had to report on the development, validation, or impact analysis of a hypertension risk prediction model. For each publication, information was extracted on study design and characteristics, predictors, model discrimination, calibration and reclassification ability, validation and impact analysis. Eleven studies reporting on 15 different hypertension prediction risk models were identified. Age, sex, body mass index, diabetes status, and blood pressure variables were the most common predictor variables included in models. Most risk models had acceptable-to-good discriminatory ability (C-statistic>0.70) in the derivation sample. Calibration was less commonly assessed, but overall acceptable. Two hypertension risk models, the Framingham and Hopkins, have been externally validated, displaying acceptable-to-good discrimination, and C-statistic ranging from 0.71 to 0.81. Lack of individual-level data precluded analyses of the risk models in subgroups. Conclusions The discrimination ability of existing hypertension risk prediction tools is acceptable, but the impact of using these tools on prescriptions and outcomes of hypertension prevention is unclear. PMID:23861760

  6. Relative risk regression models with inverse polynomials.

    PubMed

    Ning, Yang; Woodward, Mark

    2013-08-30

    The proportional hazards model assumes that the log hazard ratio is a linear function of parameters. In the current paper, we model the log relative risk as an inverse polynomial, which is particularly suitable for modeling bounded and asymmetric functions. The parameters estimated by maximizing the partial likelihood are consistent and asymptotically normal. The advantages of the inverse polynomial model over the ordinary polynomial model and the fractional polynomial model for fitting various asymmetric log relative risk functions are shown by simulation. The utility of the method is further supported by analyzing two real data sets, addressing the specific question of the location of the minimum risk threshold.

  7. Risk evaluation on the basis of pressure rate measured by automatic pressure tracking adiabatic calorimeter.

    PubMed

    Iwata, Yusaku; Koseki, Hiroshi

    2008-11-15

    An automatic pressure tracking adiabatic calorimeter (APTAC) had been employed to obtain the thermokinetic and the vapor pressure data during runaway reactions. The APTAC is an adiabatic calorimeter with a large-scale sample mass and low thermal inertia, and is an extremely useful tool for assessing thermal hazards of reactive chemicals. The data obtained by the APTAC are important information for the design of the safe industrial process. The thermodynamics parameters and the gas production were discussed on the basis of the experimental data of various concentrations and weights of di-tert-butyl peroxide (DTBP)/toluene solution for the purpose of investigating the properties of the APTAC data. The thermal decomposition of DTBP was studied on the basis of the temperature data and the pressure data obtained by the APTAC. The activation energy and the frequency factor of DTBP are nearly constant and the same as the literature values in the concentrations between 20 and 60 wt.%. The pressure rise due to gas production is important data for designing the relief vent of a reactor. The time history of the gas production was investigated with various weights and concentrations. The total gas production index, which had the vapor pressure correction, was 1.0 in the decomposition of DTBP.

  8. A Prediction Model of the Capillary Pressure J-Function

    PubMed Central

    Xu, W. S.; Luo, P. Y.; Sun, L.; Lin, N.

    2016-01-01

    The capillary pressure J-function is a dimensionless measure of the capillary pressure of a fluid in a porous medium. The function was derived based on a capillary bundle model. However, the dependence of the J-function on the saturation Sw is not well understood. A prediction model for it is presented based on capillary pressure model, and the J-function prediction model is a power function instead of an exponential or polynomial function. Relative permeability is calculated with the J-function prediction model, resulting in an easier calculation and results that are more representative. PMID:27603701

  9. Childhood Risk Factors for Thin Body Preoccupation and Social Pressure to Be Thin

    ERIC Educational Resources Information Center

    Agras, W. Stewart; Bryson, Susan; Hammer, Lawrence D.; Kraemer, Helena C.

    2007-01-01

    Objective: Thin body preoccupation and social pressure to be thin (TBPSP) in adolescence are risk factors for the development of full and partial bulimia nervosa and binge eating disorder. This study examined precursors of these potent risk factors. Method: A prospective study followed 134 children from birth to 11.0 years and their parents.…

  10. Giving in to Group Pressure: The Impact of Socialization and Risk on Perceived Outcomes

    ERIC Educational Resources Information Center

    McIntyre, Katharine A.; Platania, Judith

    2009-01-01

    The current study applies the perspective of decision theory to understanding how choices are made in an in-group setting involving social pressure and risk. Two hundred sixty-one undergraduate students provided assessments of consequences associated with illegally consuming alcohol in different environments with differing degrees of risk. In…

  11. Thermodynamic models for bounding pressurant mass requirements of cryogenic tanks

    NASA Technical Reports Server (NTRS)

    Vandresar, Neil T.; Haberbusch, Mark S.

    1994-01-01

    Thermodynamic models have been formulated to predict lower and upper bounds for the mass of pressurant gas required to pressurize a cryogenic tank and then expel liquid from the tank. Limiting conditions are based on either thermal equilibrium or zero energy exchange between the pressurant gas and initial tank contents. The models are independent of gravity level and allow specification of autogenous or non-condensible pressurants. Partial liquid fill levels may be specified for initial and final conditions. Model predictions are shown to successfully bound results from limited normal-gravity tests with condensable and non-condensable pressurant gases. Representative maximum collapse factor maps are presented for liquid hydrogen to show the effects of initial and final fill level on the range of pressurant gas requirements. Maximum collapse factors occur for partial expulsions with large final liquid fill fractions.

  12. Reswick and Rogers pressure-time curve for pressure ulcer risk. Part 1.

    PubMed

    Gefen, Amit

    Pressure ulcers are one of the most potentially devastating complications in individuals confined to a bed or a wheelchair for an extended period. Severe pressure ulcers may form in deep tissues overlying bony prominences, and only at a later stage become visible, or may even induce a full-thickness breakdown of the soft tissues at the affected site. A new type of pressure ulcer known as'deep tissue injury' has therefore been defined internationally. To understand the aetiology of deep tissue injury, health professionals should be able to predict whether or not a certain state of internal mechanical loads in deep tissues, such as tissue deformations and forces per unit area of tissue, would lead to localised irreversible cell damage. Part one of this article explains the concepts of injury thresholds as related to deep tissue injury. Some serious flaws in the classical, commonly used Reswick and Rogers pressure-time curve are analysed, and an alternative contemporary tissue injury threshold, the sigmoid threshold, is suggested. Part two of this article describes recent and ongoing work aimed at defining injury thresholds that are specific for deep tissue injury, standardised and therefore suitable for use with different patients. Clinical implications of current injury thresholds are also discussed, in relation to obese patients and patients with muscle atrophy.

  13. Mechanical Modeling of a WIPP Drum Under Pressure

    SciTech Connect

    Smith, Jeffrey A.

    2014-11-25

    Mechanical modeling was undertaken to support the Waste Isolation Pilot Plant (WIPP) technical assessment team (TAT) investigating the February 14th 2014 event where there was a radiological release at the WIPP. The initial goal of the modeling was to examine if a mechanical model could inform the team about the event. The intention was to have a model that could test scenarios with respect to the rate of pressurization. It was expected that the deformation and failure (inability of the drum to contain any pressure) would vary according to the pressurization rate. As the work progressed there was also interest in using the mechanical analysis of the drum to investigate what would happen if a drum pressurized when it was located under a standard waste package. Specifically, would the deformation be detectable from camera views within the room. A finite element model of a WIPP 55-gallon drum was developed that used all hex elements. Analyses were conducted using the explicit transient dynamics module of Sierra/SM to explore potential pressurization scenarios of the drum. Theses analysis show similar deformation patterns to documented pressurization tests of drums in the literature. The calculated failure pressures from previous tests documented in the literature vary from as little as 16 psi to 320 psi. In addition, previous testing documented in the literature shows drums bulging but not failing at pressures ranging from 69 to 138 psi. The analyses performed for this study found the drums failing at pressures ranging from 35 psi to 75 psi. When the drums are pressurized quickly (in 0.01 seconds) there is significant deformation to the lid. At lower pressurization rates the deformation of the lid is considerably less, yet the lids will still open from the pressure. The analyses demonstrate the influence of pressurization rate on deformation and opening pressure of the drums. Analyses conducted with a substantial mass on top of the closed drum demonstrate that the

  14. Requirements based system risk modeling

    NASA Technical Reports Server (NTRS)

    Meshkat, Leila; Cornford, Steven; Feather, Martin

    2004-01-01

    The problem that we address in this paper is assessing the expected degree of success of the system or mission based on the degree to which each requirement is satisfied and the relative weight of the requirements. We assume a complete list of the requirements, the relevant risk elements and their probability of occurrence and the quantified effect of the risk elements on the requirements. In order to assess the degree to which each requirement is satisfied, we need to determine the effect of the various risk elements on the requirement.

  15. High pressure common rail injection system modeling and control.

    PubMed

    Wang, H P; Zheng, D; Tian, Y

    2016-07-01

    In this paper modeling and common-rail pressure control of high pressure common rail injection system (HPCRIS) is presented. The proposed mathematical model of high pressure common rail injection system which contains three sub-systems: high pressure pump sub-model, common rail sub-model and injector sub-model is a relative complicated nonlinear system. The mathematical model is validated by the software Matlab and a virtual detailed simulation environment. For the considered HPCRIS, an effective model free controller which is called Extended State Observer - based intelligent Proportional Integral (ESO-based iPI) controller is designed. And this proposed method is composed mainly of the referred ESO observer, and a time delay estimation based iPI controller. Finally, to demonstrate the performances of the proposed controller, the proposed ESO-based iPI controller is compared with a conventional PID controller and ADRC.

  16. Genetic variants in novel pathways influence blood pressure and cardiovascular disease risk.

    PubMed

    Ehret, Georg B; Munroe, Patricia B; Rice, Kenneth M; Bochud, Murielle; Johnson, Andrew D; Chasman, Daniel I; Smith, Albert V; Tobin, Martin D; Verwoert, Germaine C; Hwang, Shih-Jen; Pihur, Vasyl; Vollenweider, Peter; O'Reilly, Paul F; Amin, Najaf; Bragg-Gresham, Jennifer L; Teumer, Alexander; Glazer, Nicole L; Launer, Lenore; Zhao, Jing Hua; Aulchenko, Yurii; Heath, Simon; Sõber, Siim; Parsa, Afshin; Luan, Jian'an; Arora, Pankaj; Dehghan, Abbas; Zhang, Feng; Lucas, Gavin; Hicks, Andrew A; Jackson, Anne U; Peden, John F; Tanaka, Toshiko; Wild, Sarah H; Rudan, Igor; Igl, Wilmar; Milaneschi, Yuri; Parker, Alex N; Fava, Cristiano; Chambers, John C; Fox, Ervin R; Kumari, Meena; Go, Min Jin; van der Harst, Pim; Kao, Wen Hong Linda; Sjögren, Marketa; Vinay, D G; Alexander, Myriam; Tabara, Yasuharu; Shaw-Hawkins, Sue; Whincup, Peter H; Liu, Yongmei; Shi, Gang; Kuusisto, Johanna; Tayo, Bamidele; Seielstad, Mark; Sim, Xueling; Nguyen, Khanh-Dung Hoang; Lehtimäki, Terho; Matullo, Giuseppe; Wu, Ying; Gaunt, Tom R; Onland-Moret, N Charlotte; Cooper, Matthew N; Platou, Carl G P; Org, Elin; Hardy, Rebecca; Dahgam, Santosh; Palmen, Jutta; Vitart, Veronique; Braund, Peter S; Kuznetsova, Tatiana; Uiterwaal, Cuno S P M; Adeyemo, Adebowale; Palmas, Walter; Campbell, Harry; Ludwig, Barbara; Tomaszewski, Maciej; Tzoulaki, Ioanna; Palmer, Nicholette D; Aspelund, Thor; Garcia, Melissa; Chang, Yen-Pei C; O'Connell, Jeffrey R; Steinle, Nanette I; Grobbee, Diederick E; Arking, Dan E; Kardia, Sharon L; Morrison, Alanna C; Hernandez, Dena; Najjar, Samer; McArdle, Wendy L; Hadley, David; Brown, Morris J; Connell, John M; Hingorani, Aroon D; Day, Ian N M; Lawlor, Debbie A; Beilby, John P; Lawrence, Robert W; Clarke, Robert; Hopewell, Jemma C; Ongen, Halit; Dreisbach, Albert W; Li, Yali; Young, J Hunter; Bis, Joshua C; Kähönen, Mika; Viikari, Jorma; Adair, Linda S; Lee, Nanette R; Chen, Ming-Huei; Olden, Matthias; Pattaro, Cristian; Bolton, Judith A Hoffman; Köttgen, Anna; Bergmann, Sven; Mooser, Vincent; Chaturvedi, Nish; Frayling, Timothy M; Islam, Muhammad; Jafar, Tazeen H; Erdmann, Jeanette; Kulkarni, Smita R; Bornstein, Stefan R; Grässler, Jürgen; Groop, Leif; Voight, Benjamin F; Kettunen, Johannes; Howard, Philip; Taylor, Andrew; Guarrera, Simonetta; Ricceri, Fulvio; Emilsson, Valur; Plump, Andrew; Barroso, Inês; Khaw, Kay-Tee; Weder, Alan B; Hunt, Steven C; Sun, Yan V; Bergman, Richard N; Collins, Francis S; Bonnycastle, Lori L; Scott, Laura J; Stringham, Heather M; Peltonen, Leena; Perola, Markus; Vartiainen, Erkki; Brand, Stefan-Martin; Staessen, Jan A; Wang, Thomas J; Burton, Paul R; Soler Artigas, Maria; Dong, Yanbin; Snieder, Harold; Wang, Xiaoling; Zhu, Haidong; Lohman, Kurt K; Rudock, Megan E; Heckbert, Susan R; Smith, Nicholas L; Wiggins, Kerri L; Doumatey, Ayo; Shriner, Daniel; Veldre, Gudrun; Viigimaa, Margus; Kinra, Sanjay; Prabhakaran, Dorairaj; Tripathy, Vikal; Langefeld, Carl D; Rosengren, Annika; Thelle, Dag S; Corsi, Anna Maria; Singleton, Andrew; Forrester, Terrence; Hilton, Gina; McKenzie, Colin A; Salako, Tunde; Iwai, Naoharu; Kita, Yoshikuni; Ogihara, Toshio; Ohkubo, Takayoshi; Okamura, Tomonori; Ueshima, Hirotsugu; Umemura, Satoshi; Eyheramendy, Susana; Meitinger, Thomas; Wichmann, H-Erich; Cho, Yoon Shin; Kim, Hyung-Lae; Lee, Jong-Young; Scott, James; Sehmi, Joban S; Zhang, Weihua; Hedblad, Bo; Nilsson, Peter; Smith, George Davey; Wong, Andrew; Narisu, Narisu; Stančáková, Alena; Raffel, Leslie J; Yao, Jie; Kathiresan, Sekar; O'Donnell, Christopher J; Schwartz, Stephen M; Ikram, M Arfan; Longstreth, W T; Mosley, Thomas H; Seshadri, Sudha; Shrine, Nick R G; Wain, Louise V; Morken, Mario A; Swift, Amy J; Laitinen, Jaana; Prokopenko, Inga; Zitting, Paavo; Cooper, Jackie A; Humphries, Steve E; Danesh, John; Rasheed, Asif; Goel, Anuj; Hamsten, Anders; Watkins, Hugh; Bakker, Stephan J L; van Gilst, Wiek H; Janipalli, Charles S; Mani, K Radha; Yajnik, Chittaranjan S; Hofman, Albert; Mattace-Raso, Francesco U S; Oostra, Ben A; Demirkan, Ayse; Isaacs, Aaron; Rivadeneira, Fernando; Lakatta, Edward G; Orru, Marco; Scuteri, Angelo; Ala-Korpela, Mika; Kangas, Antti J; Lyytikäinen, Leo-Pekka; Soininen, Pasi; Tukiainen, Taru; Würtz, Peter; Ong, Rick Twee-Hee; Dörr, Marcus; Kroemer, Heyo K; Völker, Uwe; Völzke, Henry; Galan, Pilar; Hercberg, Serge; Lathrop, Mark; Zelenika, Diana; Deloukas, Panos; Mangino, Massimo; Spector, Tim D; Zhai, Guangju; Meschia, James F; Nalls, Michael A; Sharma, Pankaj; Terzic, Janos; Kumar, M V Kranthi; Denniff, Matthew; Zukowska-Szczechowska, Ewa; Wagenknecht, Lynne E; Fowkes, F Gerald R; Charchar, Fadi J; Schwarz, Peter E H; Hayward, Caroline; Guo, Xiuqing; Rotimi, Charles; Bots, Michiel L; Brand, Eva; Samani, Nilesh J; Polasek, Ozren; Talmud, Philippa J; Nyberg, Fredrik; Kuh, Diana; Laan, Maris; Hveem, Kristian; Palmer, Lyle J; van der Schouw, Yvonne T; Casas, Juan P; Mohlke, Karen L; Vineis, Paolo; Raitakari, Olli; Ganesh, Santhi K; Wong, Tien Y; Tai, E Shyong; Cooper, Richard S; Laakso, Markku; Rao, Dabeeru C; Harris, Tamara B; Morris, Richard W; Dominiczak, Anna F; Kivimaki, Mika; Marmot, Michael G; Miki, Tetsuro; Saleheen, Danish; Chandak, Giriraj R; Coresh, Josef; Navis, Gerjan; Salomaa, Veikko; Han, Bok-Ghee; Zhu, Xiaofeng; Kooner, Jaspal S; Melander, Olle; Ridker, Paul M; Bandinelli, Stefania; Gyllensten, Ulf B; Wright, Alan F; Wilson, James F; Ferrucci, Luigi; Farrall, Martin; Tuomilehto, Jaakko; Pramstaller, Peter P; Elosua, Roberto; Soranzo, Nicole; Sijbrands, Eric J G; Altshuler, David; Loos, Ruth J F; Shuldiner, Alan R; Gieger, Christian; Meneton, Pierre; Uitterlinden, Andre G; Wareham, Nicholas J; Gudnason, Vilmundur; Rotter, Jerome I; Rettig, Rainer; Uda, Manuela; Strachan, David P; Witteman, Jacqueline C M; Hartikainen, Anna-Liisa; Beckmann, Jacques S; Boerwinkle, Eric; Vasan, Ramachandran S; Boehnke, Michael; Larson, Martin G; Järvelin, Marjo-Riitta; Psaty, Bruce M; Abecasis, Gonçalo R; Chakravarti, Aravinda; Elliott, Paul; van Duijn, Cornelia M; Newton-Cheh, Christopher; Levy, Daniel; Caulfield, Mark J; Johnson, Toby

    2011-09-11

    Blood pressure is a heritable trait influenced by several biological pathways and responsive to environmental stimuli. Over one billion people worldwide have hypertension (≥140 mm Hg systolic blood pressure or  ≥90 mm Hg diastolic blood pressure). Even small increments in blood pressure are associated with an increased risk of cardiovascular events. This genome-wide association study of systolic and diastolic blood pressure, which used a multi-stage design in 200,000 individuals of European descent, identified sixteen novel loci: six of these loci contain genes previously known or suspected to regulate blood pressure (GUCY1A3-GUCY1B3, NPR3-C5orf23, ADM, FURIN-FES, GOSR2, GNAS-EDN3); the other ten provide new clues to blood pressure physiology. A genetic risk score based on 29 genome-wide significant variants was associated with hypertension, left ventricular wall thickness, stroke and coronary artery disease, but not kidney disease or kidney function. We also observed associations with blood pressure in East Asian, South Asian and African ancestry individuals. Our findings provide new insights into the genetics and biology of blood pressure, and suggest potential novel therapeutic pathways for cardiovascular disease prevention.

  17. Modeling High Pressure Micro Hollow Cathode Discharges

    DTIC Science & Technology

    2007-11-02

    calculations in glow discharge in argon and neon . A Monte Carlo simulation of the ions and Grant 033083 – Final report 7 the fast neutrals generated...in high pressure xenon or in rare gas mixtures containing xenon are of interest in the context of UV and VUV generation. Numerical experiments on...The shape of the calculated characteristic is similar to those measured by Schoenbach et al1 in argon and by Moselhy and Schoenbach9 in xenon . There

  18. Kinetic modelling of pressure filtration of ceramic powder suspensions

    SciTech Connect

    Correia, L.A.; Salomoni, A.; Hey, A.W.

    1995-09-01

    A kinetic model developed for radial pressure filtration is described and used to study the casting behaviour of an Alumina (Al6SG) and a Zirconia (TZ3Ys) slip stabilized with Dolapix CE64. For the Zirconia slip no influence of pressure and curvature is found. The casting behaviour of the Alumina slip seems to be influenced by both the pressure and the curvature of the filtrating surface.

  19. Probabilistic Modeling of Intracranial Pressure Effects on Optic Nerve Biomechanics

    NASA Technical Reports Server (NTRS)

    Ethier, C. R.; Feola, Andrew J.; Raykin, Julia; Myers, Jerry G.; Nelson, Emily S.; Samuels, Brian C.

    2016-01-01

    Altered intracranial pressure (ICP) is involved/implicated in several ocular conditions: papilledema, glaucoma and Visual Impairment and Intracranial Pressure (VIIP) syndrome. The biomechanical effects of altered ICP on optic nerve head (ONH) tissues in these conditions are uncertain but likely important. We have quantified ICP-induced deformations of ONH tissues, using finite element (FE) and probabilistic modeling (Latin Hypercube Simulations (LHS)) to consider a range of tissue properties and relevant pressures.

  20. Root Caries Risk Indicators: A Systematic Review of Risk Models

    PubMed Central

    Ritter, André V.; Shugars, Daniel A.; Bader, James D.

    2010-01-01

    Objective To identify risk indicators that are associated with root caries incidence in published predictive risk models. Methods Abstracts (n=472) identified from a MEDLINE, EMBASE, and Cochrane registry search were screened independently by two investigators to exclude articles not in English (n=39), published prior to 1970 (none), or containing no information on either root caries incidence, risk indicators, or risk models (n=209). A full-article duplicate review of the remaining articles (n=224) selected those reporting predictive risk models based on original/primary longitudinal root caries incidence studies. The quality of the included articles was assessed based both on selected criteria of methodological standards for observational studies and on the statistical quality of the modeling strategy. Data from these included studies were extracted and compiled into evidence tables, which included information about the cohort location, incidence period, sample size, age of the study participants, risk indicators included in the model, root caries incidence, modeling strategy, significant risk indicators/predictors, and parameter estimates and statistical findings. Results Thirteen articles were selected for data extraction. The overall quality of the included articles was poor to moderate. Root caries incidence ranged fro m 12%–77% (mean±SD=45%±17%); follow-up time of the published studies was ≤10 years (range=9; median=3); sample size ranged from 23–723 (mean±SD=264±203; median=261); person-years ranged from 23–1540 (mean±SD=760±556; median=746). Variables most frequently tested and significantly associated with root caries incidence were (times tested; % significant; directionality): baseline root caries (12; 58%; positive); number of teeth (7; 71%; 3 times positive, twice negative), and plaque index (4; 100%; positive). Ninety-two other clinical and non-clinical variables were tested: 27 were tested 3 times or more and were significant between 9

  1. Length of surgery and pressure ulcers risk in cardiovascular surgical patients: a dose-response meta-analysis.

    PubMed

    Chen, Hong-Lin; Shen, Wang-Qin; Liu, Peng; Liu, Kun

    2017-03-02

    The aim of this study was to assess the relationship between length of surgery (LOS) and pressure ulcer (PU) risk in cardiovascular surgery patients. PubMed and Web of Science were systematically searched. We compared LOS difference between PU (+) group and PU (-) group. We also examined the dose-response effect of this relationship. The mean LOS in the PU(+) groups ranged from 252·5 to 335·7 minutes, compared with 233·0 to 298·3 minutes in PU(-) groups. The LOS was higher in PU(+) groups compared with PU(-) groups [weighted mean difference (WMD) = 36·081 minutes; 95% CI: 21·640-50·522 minutes; Z = 4·90, P = 0·000]. The funnel plot showed no publication bias. A significant dose-response association was also found between the LOS and the risk of surgery-related pressure ulcers (SRPU, model χ(2)  = 9·29, P = 0·000). In the linear model, the PU OR was 1·296 (95% CI 1·097-1·531) for a 60-minute increase in the LOS intervals and 13·344 (95% CI 2·521-70·636) for a 600-minute increase. In a spline model, the OR of PU increased almost linearly along with the LOS. Our meta-analysis indicated that LOS was an important risk factor for pressure ulcers in cardiovascular surgical patients.

  2. Visual Impairment/lntracranial Pressure Risk Clinical Care Data Tools

    NASA Technical Reports Server (NTRS)

    Van Baalen, Mary; Mason, Sara S.; Taiym, Wafa; Wear, Mary L.; Moynihan, Shannan; Alexander, David; Hart, Steve; Tarver, William

    2014-01-01

    Prior to 2010, several ISS crewmembers returned from spaceflight with changes to their vision, ranging from a mild hyperopic shift to frank disc edema. As a result, NASA expanded clinical vision testing to include more comprehensive medical imaging, including Optical Coherence Tomography and 3 Tesla Brain and Orbit MRIs. The Space and Clinical Operations (SCO) Division developed a clinical practice guideline that classified individuals based on their symptoms and diagnoses to facilitate clinical care. For the purposes of clinical surveillance, this classification was applied retrospectively to all crewmembers who had sufficient testing for classification. This classification is also a tool that has been leveraged for researchers to identify potential risk factors. In March 2014, driven in part by a more comprehensive understanding of the imaging data and increased imaging capability on orbit, the SCO Division revised their clinical care guidance to outline in-flight care and increase post-flight follow up. The new clinical guidance does not include a classification scheme

  3. Pressurized water reactor fuel crud and corrosion modeling

    NASA Astrophysics Data System (ADS)

    Deshon, Jeff; Hussey, Dennis; Kendrick, Brian; McGurk, John; Secker, Jeff; Short, Michael

    2011-08-01

    Pressurized water reactors circulate high-temperature water that slowly corrodes Inconel and stainless steel system surfaces, and the nickel/iron based corrosion products deposit in regions of the fuel where sub-cooled nucleate boiling occurs. The deposited corrosion products, called `crud', can have an adverse impact on fuel performance. Boron can concentrate within the crud in the boiling regions of the fuel leading to a phenomenon known as axial offset anomaly (AOA). In rare cases, fuel clad integrity can be compromised because of crud-induced localized corrosion (CILC) of the zirconium-based alloy. Westinghouse and the Electric Power Research Institute have committed to understanding the crud transport process and develop a risk assessment software tool called boron-induced offset anomaly (BOA) to avoid AOA and CILC. This paper reviews the history of the BOA model development and new efforts to develop a micro-scale model called MAMBA for use in the Consortium for Advanced Light Water Reactor Simulation (CASL) program.

  4. A methodology for modeling regional terrorism risk.

    PubMed

    Chatterjee, Samrat; Abkowitz, Mark D

    2011-07-01

    Over the past decade, terrorism risk has become a prominent consideration in protecting the well-being of individuals and organizations. More recently, there has been interest in not only quantifying terrorism risk, but also placing it in the context of an all-hazards environment in which consideration is given to accidents and natural hazards, as well as intentional acts. This article discusses the development of a regional terrorism risk assessment model designed for this purpose. The approach taken is to model terrorism risk as a dependent variable, expressed in expected annual monetary terms, as a function of attributes of population concentration and critical infrastructure. This allows for an assessment of regional terrorism risk in and of itself, as well as in relation to man-made accident and natural hazard risks, so that mitigation resources can be allocated in an effective manner. The adopted methodology incorporates elements of two terrorism risk modeling approaches (event-based models and risk indicators), producing results that can be utilized at various jurisdictional levels. The validity, strengths, and limitations of the model are discussed in the context of a case study application within the United States.

  5. Empirical Model of the Pressure in the Earth's Ring Current

    NASA Astrophysics Data System (ADS)

    Sotirelis, T.; Gkioulidou, M.; Ukhorskiy, A. Y.; MacDonald, E.

    2014-12-01

    Plasma in the inner magnetosphere produces the Earth's ring current through its pressure. Changes in the plasma pressure dramatically effects the ring current, and the magnetic field which guides particle motion. Here, the pressure in the inner magnetosphere is empirically modeled using Van Allen Probes observations by the RBSPICE and ECT-HOPE instruments. The radial and local-time dependence of both the parallel and perpendicular components of plasma pressure are assessed and the contributions of Helium and Oxygen are measured. Correlation studies are used to further understand the causal roles played by various drivers. Simultaneous observations from the two Van Allen Probes permit an understanding of global versus local variations.

  6. The incidence, risk factors and characteristics of pressure ulcers in hospitalized patients in China

    PubMed Central

    Jiang, Qixia; Li, Xiaohua; Qu, Xiaolong; Liu, Yun; Zhang, Liyan; Su, Chunyin; Guo, Xiujun; Chen, Yuejuan; Zhu, Yajun; Jia, Jing; Bo, Suping; Liu, Li; Zhang, Rui; Xu, Ling; Wu, Leyan; Wang, Hai; Wang, Jiandong

    2014-01-01

    Pressure ulcers are very common in hospital patients. Though many studies have been reported in many countries, the large-scale benchmarking prevalence of pressure ulcers in China is not available. The aim of this study is to quantify the prevalence of pressure ulcers and the incidence of hospital-acquired pressure ulcers and analyze risk factors in hospitalized patients in China. A multi-central cross-sectional survey was conducted in one university hospital and 11 general hospitals in China. The Minimum Data Set (MDS) recommended by European Pressure Ulcer Advisory Panel (EUPAP) was used to collect information of inpatients. All patients stayed in hospital more than 24 hours and older than 18 years signed consent form and were included. Data from 39952 out of 40415 (98.85%) inpatients were analyzed. Of the 39952 patients, 631 patients (including 1024 locations) had pressure ulcers. The prevalence rate of pressure ulcers in 12 hospitals was 1.58% (0.94-2.97%). The incidence of hospital-acquired pressure ulcers (HAPU) was 0.63% (0.20-1.20%). The most common locations developed pressure ulcers were sacrum, heels, and iliac crests. The common stages of pressure ulcers were stage I and II. Patients in Intensive Care Unit, Geriatric and Neurological Department were easier to develop pressure ulcers. The prevalence and incidence of pressure ulcers in China was lower than that reported in European and other countries. The stages of pressure ulcers in China were different than that reported in European countries. Our study provides with a baseline value for intensive research on pressure ulcer in China. PMID:24966973

  7. Justification pressure in risky decision making: search for risk defusing operators.

    PubMed

    Huber, Oswald; Bär, Arlette S; Huber, Odilo W

    2009-01-01

    Under justification pressure, the decision maker knows in advance that the decision has to be justified to somebody afterwards. The effect of justification pressure on the search for risk defusing operators (RDOs) and the role of RDOs in the justification texts were investigated. An RDO is an action intended by the decision maker to be performed in addition to an otherwise attractive alternative to decrease the risk. As predicted, in Experiment 1 participants (60 non-students) under justification pressure searched more RDOs. Additionally, in Experiment 2 (80 non-students) RDO search success was varied. Under justification pressure, persistence of RDO search was higher when no RDO could be detected. In the justification texts, the existence or non-existence of RDOs played a prominent role. Searching for RDOs supports people in their goal to make a good decision and in their attempt to convince the addressee of their justification that the decision was good.

  8. Home, automated office, and conventional office blood pressure as predictors of cardiovascular risk.

    PubMed

    Andreadis, Emmanuel A; Papademetriou, Vasilios; Geladari, Charalampia V; Kolyvas, George N; Angelopoulos, Epameinondas T; Aronis, Konstantinos N

    2017-02-03

    Automated office blood pressure (AOBP) has recently been shown to closely predict cardiovascular (CV) events in the elderly. Home blood pressure (HBP) has also been accepted as a valuable method in the prediction of CV disease. This study aimed to compare conventional office BP (OBP), HBP, and AOBP in order to evaluate their value in predicting CV events and deaths in hypertensives. We assessed 236 initially treatment naïve hypertensives, examined between 2009 and 2013. The end points were any CV and non-CV event including mortality, myocardial infarction, coronary heart disease, hospitalization for heart failure, severe arrhythmia, stroke, and intermittent claudication. We fitted proportional hazards models using the different modalities as predictors and evaluated their predictive performance using three metrics: time-dependent receiver operating characteristics curves, the Akaike's Information Criterion, and Harrell's C-index. After a mean follow-up of 7 years, 23 participants (39% women) had experienced ≥1 CV event. Conventional office systolic (hazard ratio [HR] per 1 mm Hg increase in BP, 1.028; 95% confidence interval [CI], 1.009-1.048), automated office systolic (HR per 1 mm Hg increase in BP, 1.031; 95% CI, 1.008-1.054), and home systolic (HR, 1.025; 95% CI, 1.003-1.047) were predictive of CV events. All systolic BP measurements were predictive after adjustment for other CV risk factors (P < .05). The predictive performance of the different modalities was similar. Conventional OBP was significantly higher than AOBP and average HBP. AOBP predicts equally well to OBP and HBP CV events. It appears to be comparable to HBP in the assessment of CV risk, and therefore, its introduction into guidelines and clinical practice as the reference method for assessing BP in the office seems reasonable after verification of these findings by randomized trials.

  9. Adversarial risk analysis for counterterrorism modeling.

    PubMed

    Rios, Jesus; Rios Insua, David

    2012-05-01

    Recent large-scale terrorist attacks have raised interest in models for resource allocation against terrorist threats. The unifying theme in this area is the need to develop methods for the analysis of allocation decisions when risks stem from the intentional actions of intelligent adversaries. Most approaches to these problems have a game-theoretic flavor although there are also several interesting decision-analytic-based proposals. One of them is the recently introduced framework for adversarial risk analysis, which deals with decision-making problems that involve intelligent opponents and uncertain outcomes. We explore how adversarial risk analysis addresses some standard counterterrorism models: simultaneous defend-attack models, sequential defend-attack-defend models, and sequential defend-attack models with private information. For each model, we first assess critically what would be a typical game-theoretic approach and then provide the corresponding solution proposed by the adversarial risk analysis framework, emphasizing how to coherently assess a predictive probability model of the adversary's actions, in a context in which we aim at supporting decisions of a defender versus an attacker. This illustrates the application of adversarial risk analysis to basic counterterrorism models that may be used as basic building blocks for more complex risk analysis of counterterrorism problems.

  10. Clustering of cardiovascular behavioral risk factors and blood pressure among people diagnosed with hypertension: a nationally representative survey in China

    PubMed Central

    Li, Yichong; Feng, Xiaoqi; Zhang, Mei; Zhou, Maigeng; Wang, Ning; Wang, Limin

    2016-01-01

    This study aimed to examine association between the number of behavioral risk factors and blood pressure (BP) level among a nationally representative sample of Chinese people diagnosed with hypertension. A total of 31,694 respondents aged 18+ years with diagnosed hypertension were extracted from the 2013–2014 China Chronic Disease and Risk Factor Surveillance. BP of each respondent was classified into six levels according to criteria in 2007 Guidelines for the Management of Arterial Hypertension. Information for smoking, alcohol drinking, fruit and vegetables consumption, physical inactivity, and overweight and obesity were obtained. The average number of risk factors was determined by BP level to explore potential risk factor clustering. Ten generalized proportional odds models were used to examine association between clustering of behavioral risk factors and BP level. A clear gradient between the number of behavioral risk factors and BP level was observed for men and women (P < 0.05 for both genders). BP level for men and women was much likely to upgrade as number of risk factors accumulated (P < 0.01 for 10 models). Behavioral modifications may decrease BP, and combinations of two or more behavioral interventions could potentially result in even better BP management among people diagnosed with hypertension. PMID:27279273

  11. Low temperature ablation models made by pressure/vacuum application

    NASA Technical Reports Server (NTRS)

    Fischer, M. C.; Heier, W. C.

    1970-01-01

    Method developed employs high pressure combined with strong vacuum force to compact ablation models into desired conical shape. Technique eliminates vapor hazard and results in high material density providing excellent structural integrity.

  12. Quantifying fatigue risk in model-based fatigue risk management.

    PubMed

    Rangan, Suresh; Van Dongen, Hans P A

    2013-02-01

    The question of what is a maximally acceptable level of fatigue risk is hotly debated in model-based fatigue risk management in commercial aviation and other transportation modes. A quantitative approach to addressing this issue, referred to by the Federal Aviation Administration with regard to its final rule for commercial aviation "Flightcrew Member Duty and Rest Requirements," is to compare predictions from a mathematical fatigue model against a fatigue threshold. While this accounts for duty time spent at elevated fatigue risk, it does not account for the degree of fatigue risk and may, therefore, result in misleading schedule assessments. We propose an alternative approach based on the first-order approximation that fatigue risk is proportional to both the duty time spent below the fatigue threshold and the distance of the fatigue predictions to the threshold--that is, the area under the curve (AUC). The AUC approach is straightforward to implement for schedule assessments in commercial aviation and also provides a useful fatigue metric for evaluating thousands of scheduling options in industrial schedule optimization tools.

  13. Ultra-High Pressure Modeling and Experiments Review

    SciTech Connect

    Costantino, M; Darnell, I

    2004-06-01

    The RDHWT/MARIAH II energy addition, run time, and mass flow rate requirement simply large air and nitrogen fluid volumes at the highest practicable static enthalpy. The objective of the gas supply concept development is the satisfaction of ultra-high pressure (UHP), high temperature thermodynamic requirements in a facility with acceptable safety and economic risks. The primary challenges for the mechanical design are connecting multiple volumes at pressures greater than 1,400MPa and temperatures greater than 500 K; fabricating high strength steel sections approximately 2 m in typical dimension, and reacting the pressure-related forces in the system. In the 'octahedral module' concept, four UHP intensifiers and two UHP manifolds are arranged in an 'octahedral' geometry that results in acceptable deviatoric stresses at cross bores. Multiple modules join to provide the required UHP volume at a stagnation pressure of 2100MPa and stagnation temperature of 750 K.

  14. Importance of sustained and "tight" blood pressure control in patients with high cardiovascular risk.

    PubMed

    Meredith, Peter A; Lloyd, Suzanne M; Ford, Ian; Elliott, Henry L

    2016-01-01

    A retrospective further analysis of the ACTION database evaluated the relationship between cardiovascular outcomes and the "quality" of the control of blood pressure (BP). The study population (n = 6287) comprised those patients with four BP measurements during year 1 subdivided according to the proportion of visits in which BP was controlled in relation to two BP targets: < 140/90mmHg and < 130/80 mmHg. Differences between the BP control groups for the major prespecified ACTION outcomes were investigated with Cox proportional hazards models. For all the prespecified cardiovascular endpoints the incidence declined as the proportion of visits with BP control increased. The greatest differences in outcomes between the different BP control groups were observed for the risk of stroke but were still apparent for all the other endpoints. For example, the risks for the primary outcome [hazard ratio (HR) 0.78; 95% confidence interval (CI) 0.67 to 0.90] were significantly less in the group with >_75% of visits with BP control than in the group with < 25% of visits with BP control. There were no significant treatment-related differences. Retrospective analyses are not definitive but these results highlight the importance of the attainment of BP control targets and the consistency of BP control during long-term follow-up.

  15. Measures of Residual Risk with Connections to Regression, Risk Tracking, Surrogate Models, and Ambiguity

    DTIC Science & Technology

    2015-01-07

    Measures of Residual Risk with Connections to Regression, Risk Tracking, Surrogate Models, and Ambiguity1 R. Tyrrell Rockafellar Johannes O. Royset...insights and a new class of distributionally robust optimization models. Keywords: risk measures, residual risk, generalized regression, surrogate ...Measures of Residual Risk with Connections to Regression, Risk Tracking, Surrogate Models, and Ambiguity 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c

  16. Modelling suicide risk in later life.

    PubMed

    Lo, C F; Kwok, Cordelia M Y

    2006-08-01

    Affective disorder is generally regarded as the prominent risk factor for suicide in the old age population. Despite the large number of empirical studies available in the literature, there is no attempt in modelling the dynamics of an individual's level of suicide risk theoretically yet. In particular, a dynamic model which can simulate the time evolution of an individual's level of risk for suicide and provide quantitative estimates of the probability of suicide risk is still lacking. In the present study we apply the contingent claims analysis of credit risk modelling in the field of quantitative finance to derive a theoretical stochastic model for estimation of the probability of suicide risk in later life in terms of a signalling index of affective disorder. Our model is based upon the hypothesis that the current state of affective disorder of a patient can be represented by a signalling index and exhibits stochastic movement and that a threshold of affective disorder, which signifies the occurrence of suicide, exists. According to the numerical results, the implications of our model are consistent with the clinical findings. Hence, we believe that such a dynamic model will be essential to the design of effective suicide prevention strategies in the target population of older adults, especially in the primary care setting.

  17. Risk, prevention and treatment of pressure ulcers--nursing staff knowledge and documentation.

    PubMed

    Gunningberg, L; Lindholm, C; Carlsson, M; Sjödén, P O

    2001-01-01

    The aims were to investigate (i) registered nurses' and nursing assistants' knowledge of risk, prevention and treatment of pressure ulcer before implementing a system for risk assessment and pressure ulcer classification for patients with hip fracture (ii) interventions documented in the patient's records by registered nurses, and (iii) to what extent reported and documented interventions accord with the Swedish quality guidelines. Nursing staff (n=85) completed a questionnaire, and patient's records (n=55) were audited retrospectively. The majority of the nursing staff reported that they performed risk assessment when caring for a patient with hip fracture. These risk assessments were, however, not comprehensive. The most frequently reported preventive interventions were repositioning, use of lotion, mattresses/overlays and cushions for the heels. These interventions were to some extent documented in the patient's records. Nutritional support, reduction of shear and friction, hygiene and skin moisture, and patient's education were reported to a small extent and not documented at all. The Swedish quality guidelines regarding prevention and treatment of pressure ulcers were not fully implemented in clinical practice. It was concluded that nursing staff's knowledge and documentation of risk, prevention and treatment of pressure ulcers for patients with hip fractures could be improved.

  18. Modelling oxygen self-diffusion in UO2 under pressure

    DOE PAGES

    Cooper, Michael William D.; Grimes, R. W.; Fitzpatrick, M. E.; ...

    2015-10-22

    Access to values for oxygen self-diffusion over a range of temperatures and pressures in UO2 is important to nuclear fuel applications. Here, elastic and expansivity data are used in the framework of a thermodynamic model, the cBΩ model, to derive the oxygen self-diffusion coefficient in UO2 over a range of pressures (0–10 GPa) and temperatures (300–1900 K). Furthermore, the significant reduction in oxygen self-diffusion as a function of increasing hydrostatic pressure, and the associated increase in activation energy, is identified.

  19. Integrated Environmental Modeling: Quantitative Microbial Risk Assessment

    EPA Science Inventory

    The presentation discusses the need for microbial assessments and presents a road map associated with quantitative microbial risk assessments, through an integrated environmental modeling approach. A brief introduction and the strengths of the current knowledge are illustrated. W...

  20. Improved Solar-Radiation-Pressure Models for GPS Satellites

    NASA Technical Reports Server (NTRS)

    Bar-Sever, Yoaz; Kuang, Da

    2006-01-01

    A report describes a series of computational models conceived as an improvement over prior models for determining effects of solar-radiation pressure on orbits of Global Positioning System (GPS) satellites. These models are based on fitting coefficients of Fourier functions of Sun-spacecraft- Earth angles to observed spacecraft orbital motions.

  1. An asperity-deformation model for effective pressure

    NASA Astrophysics Data System (ADS)

    Gangi, Anthony F.; Carlson, Richard L.

    1996-05-01

    Variations of the mechanical and transport properties of cracked and/or porous rocks under isotropic stress depend on both the confining pressure ( Pc) and the pore-fluid pressure ( Pp). To a first approximation, these rock properties are functions of the differential pressure, Pd = Pc - Pp; at least for low differential pressures. However, at higher differential pressures, the properties depend in a more complicated way upon the two pressures. The concept of effective pressure, Pe, is used to denote this variation and it is defined as Pe( Pc, Pp) = Pc - n( Pc, Pp) Pp. If n = 1 (and therefore, is independent of Pc and Pp), the effective pressure is just the differential pressure. We have used an asperity-deformation model and a force-balance equation to derive expressions for the effective pressure. We equate the total external force (in one direction), Fc, to the total force on the asperities, Fa, and the force of the fluid, Fp, acting in that same direction. The fluid force, Fp, acts only on the parts of the crack (or pore-volume) faces which are not in contact. Then, the asperity pressure, Pa, is the average force per unit area acting on the crack (or grain) contacts P a = {F a}/{A} = {F c}/{A} - {F p}/{A} = P c - (1 - {A c}/{A})P p, where A is the total area over which Fc acts and Ac is the area of contact of the crack asperities or the grains. Thus, the asperity pressure, Pa, is greater than the differential pressure, Pd, because Pp acts on a smaller area, A- Ac, than the total area, A. For elastic asperities, the area of contact Ac and the strain (e.g., crack and pore openings) remain the same, to a high degree of approximation, at constant asperity pressure. Therefore, transport properties such as permeability, resistivity, thermal conductivity, etc. are constant, to the same degree of approximation, at constant asperity pressure. For these properties, the asperity pressure is, very accurately, the effective pressure, Pc. Using this model, we find that the

  2. A pressure-deformation analytical model for rectangular diaphragm of MEMS pressure sensors

    NASA Astrophysics Data System (ADS)

    Zhou, Wu; Wang, Dong; Yu, Huijun; Peng, Bei

    2017-02-01

    Rectangular diaphragm is commonly used as a pressure sensitive component in MEMS pressure sensors. Its deformation under applied pressure directly determines the performance of micro-devices, accurately acquiring the pressure-deflection relationship, therefore, plays a significant role in pressure sensor design. This paper analyzes the deflection of an isotropic rectangular diaphragm under combined effects of loads. The model is regarded as a clamped plate with full surface uniform load and partially uniform load applied on its opposite sides. The full surface uniform load stands for the external measured pressure. The partial load is used to approximate the opposite reaction of the silicon island which is planted on the diaphragm to amplify the deformation displacement, thus to improve the sensitivity of the pressure sensor. Superposition method is proposed to calculate the diaphragm deflections. This method considers separately the actions of loads applied on the simple supported plate and moments distributed on edges. Considering the boundary condition of all edges clamped, the moments are constructed to eliminate the boundary rotations caused by lateral load. The diaphragm’s deflection is computed by superposing deflections which produced by loads applied on the simple supported plate and moments distributed on edges. This method provides higher calculation accuracy than Galerkin variational method, and it is used to analyze the influence factors of the diaphragm’s deflection, includes aspect ratio, thickness and the applied force area of the diaphragm.

  3. Blood Pressure Variability: Can Nonlinear Dynamics Enhance Risk Assessment During Cardiovascular Surgery? A Feasibility Study

    PubMed Central

    Subramaniam, Balachundhar; Khabbaz, Kamal R.; Heldt, Thomas; Lerner, Adam B.; Mittleman, Murray A.; Davis, Roger B.; Goldberger, Ary L.; Costa, Madalena D.

    2014-01-01

    Brief Summary We propose that complex (nonlinear) fluctuations of hemodynamic variables (including systemic blood pressure parameters) during cardiovascular surgery contain information relevant to risk assessment and intraoperative management. Preliminary analysis of a pilot study supports the feasibility and potential merits of performing a larger, prospective study to assess the clinical utility of such new dynamical measures and to evaluate their potential role in enhancing contemporary approaches to risk assessment of major adverse events. PMID:24508020

  4. Thresholds for Diagnosing Hypertension Based on Automated Office Blood Pressure Measurements and Cardiovascular Risk.

    PubMed

    Myers, Martin G; Kaczorowski, Janusz; Paterson, J Michael; Dolovich, Lisa; Tu, Karen

    2015-09-01

    The risk of cardiovascular events in relation to blood pressure is largely based on readings taken with a mercury sphygmomanometer in populations which differ from those of today in terms of hypertension severity and drug therapy. Given replacement of the mercury sphygmomanometer with electronic devices, we sought to determine the blood pressure threshold for a significant increase in cardiovascular risk using a fully automated device, which takes multiple readings with the subject resting quietly alone. Participants were 3627 community-dwelling residents aged >65 years untreated for hypertension. Automated office blood pressure readings were obtained in a community pharmacy with subjects seated and undisturbed. This method for recording blood pressure produces similar readings in different settings, including a pharmacy and family doctor's office providing the above procedures are followed. Subjects were followed for a mean (SD) of 4.9 (1.0) years for fatal and nonfatal cardiovascular events. Adjusted hazard ratios (95% confidence intervals) were computed for 10 mm Hg increments in blood pressure (mm Hg) using Cox proportional hazards regression and the blood pressure category with the lowest event rate as the reference category. A total of 271 subjects experienced a cardiovascular event. There was a significant (P=0.02) increase in the hazard ratio of 1.66 (1.09, 2.54) at a systolic blood pressure of 135 to 144 and 1.72 (1.21, 2.45; P=0.003) at a diastolic blood pressure of 80 to 89. A significant (P=0.03) increase in hazard ratio of 1.73 (1.04, 2.86) occurred with a pulse pressure of 80 to 89. These findings are consistent with a threshold of 135/85 for diagnosing hypertension in older subjects using automated office blood pressure.

  5. Constructing high-pressure thermodynamic models: problems and possible solutions

    NASA Astrophysics Data System (ADS)

    Brosh, E.

    2013-12-01

    Conventional thermodynamic databases (e.g. Fabrichnaya et al. 2004, Holland and Powell 1998, 2011) consist of expressions for the Gibbs energy at ambient pressure, extended to higher pressures through the integration of some EOS (Equation Of State). While this is simple and straight-forward, such thermodynamic models are prone to produce manifestly unphysical predictions of negative thermal expansion and even negative heat capacity at high pressure. It has been shown (Brosh et al. 2007) that these errors arise not only from problems the EOS itself but also from incompatibilities between the EOS and the models used for extrapolations of the heat capacity at ambient pressure. One solution is a radical restructuring of thermodynamic databases. Instead of modelling the Gibbs energy, new databases can be based on modelling the Helmholtz energy using Debye-Mie-Grüneisen EOS. This approach is very successful for modelling solid substances (Jacobs 2009, 2010, Dorogokupets et al. 2007, 2012) but the Debye-Mie-Grüneisen equations of state are not easily applicable to liquids. Other difficulties stem from the treatment of the predicted mechanical instability above the normal melting point. However, the most severe difficulty with the utilization of the Debye-Mie-Grüneisen approach is that it is incompatible with the current ambient-pressure thermodynamic databases and one will not be able to use them as a basis for high pressure modelling. Another approach (Brosh et al. 2007) is based on an interpolation of the thermophysical properties between the ambient pressure models given in conventional databases and the Debye-Mie-Grüneisen model at extreme pressures. This avoids most of the spurious anomalies of conventional models. The limitations of the interpolation scheme are the inclusion of several model parameters whose physical essence is not well-defined and an underestimation of the heat capacity at high pressures. In this presentation, the predictions of the

  6. Pressure and velocity profiles in a static mechanical hemilarynx model.

    PubMed

    Alipour, Fariborz; Scherer, Ronald C

    2002-12-01

    This study examined pressure and velocity profiles in a hemilarynx mechanical model of phonation. The glottal section had parallel walls and was fabricated from hard plastic. Twelve pressure taps were created in the vocal fold surface and connected to a differential pressure transducer through a pressure switch. The glottal gap was measured with feeler gauges and the uniform glottal duct was verified by use of a laser system. Eight pressure transducers were placed in the flat wall opposite the vocal fold. Hot-wire anemometry was used to obtain velocity profiles upstream and downstream of the glottis. The results indicate that the pressure distribution on the vocal fold surface was consistent with pressure change along a parallel duct, whereas the pressures on the opposite flat wall typically were lower (by 8%-40% of the transglottal pressure just past mid-glottis). The upstream velocity profiles were symmetric regardless of the constriction shape and size. The jet flow downstream of the glottis was turbulent even for laminar upstream conditions. The front of the jet was consistently approximately 1.5 mm from the flat wall for glottal gaps of 0.4, 0.8 and 1.2 mm. The turbulence intensity also remained approximately at the same location of about 4 mm from the flat wall for the two larger gaps.

  7. Cryogenic Pressure Control Modeling for Ellipsoidal Space Tanks

    NASA Technical Reports Server (NTRS)

    Lopez, Alfredo; Grayson, Gary D.; Chandler, Frank O.; Hastings, Leon J.; Heyadat, Ali

    2007-01-01

    A computational fluid dynamics (CFD) model is developed to simulate pressure control of an ellipsoidal-shaped liquid hydrogen tank under external heating in normal gravity. Pressure control is provided by an axial jet thermodynamic vent system (TVS) centered within the vessel that injects cooler liquid into the tank, mixing the contents and reducing tank pressure. The two-phase cryogenic tank model considers liquid hydrogen in its own vapor with liquid density varying with temperature only and a fully compressible ullage. The axisymmetric model is developed using a custom version of the commercially available FLOW-31) software. Quantitative model validation is ,provided by engineering checkout tests performed at Marshall Space Flight Center in 1999 in support of the Solar Thermal Upper Stage_ Technology Demonstrator (STUSTD) program. The engineering checkout tests provide cryogenic tank self-pressurization test data at various heat leaks and tank fill levels. The predicted self-pressurization rates, ullage and liquid temperatures at discrete locations within the STUSTD tank are in good agreement with test data. The work presented here advances current CFD modeling capabilities for cryogenic pressure control and helps develop a low cost CFD-based design process for space hardware.

  8. Two criteria for evaluating risk prediction models.

    PubMed

    Pfeiffer, R M; Gail, M H

    2011-09-01

    We propose and study two criteria to assess the usefulness of models that predict risk of disease incidence for screening and prevention, or the usefulness of prognostic models for management following disease diagnosis. The first criterion, the proportion of cases followed PCF (q), is the proportion of individuals who will develop disease who are included in the proportion q of individuals in the population at highest risk. The second criterion is the proportion needed to follow-up, PNF (p), namely the proportion of the general population at highest risk that one needs to follow in order that a proportion p of those destined to become cases will be followed. PCF (q) assesses the effectiveness of a program that follows 100q% of the population at highest risk. PNF (p) assess the feasibility of covering 100p% of cases by indicating how much of the population at highest risk must be followed. We show the relationship of those two criteria to the Lorenz curve and its inverse, and present distribution theory for estimates of PCF and PNF. We develop new methods, based on influence functions, for inference for a single risk model, and also for comparing the PCFs and PNFs of two risk models, both of which were evaluated in the same validation data.

  9. Pressure transient modeling of a fractured geothermal reservior

    SciTech Connect

    Robinson, B.A.

    1990-01-01

    A fracture network model has been developed to simulate transient fluid flow behavior in a fractured rock mass. Included is a pressure-dependent aperture submodel to simulate behavior often seen in fractured systems. The model is used to simulate data from the Fenton Hill Hot Dry Rock (HDR) geothermal reservoir. Both low-pressure/low-flow-rate and high-pressure/high-flow-rate transient data are adequately simulated. The model parameters obtained suggest ways in which the model can be refined to achieve even more realistic fits to the data. The model is then used to demonstrate more efficient operating modes than the two-well circulating mode usually proposed for HDR reservoirs. 11 refs., 9 figs., 1 tab.

  10. Microscopic pressure-cooker model for studying molecules in confinement

    NASA Astrophysics Data System (ADS)

    Santamaria, Ruben; Adamowicz, Ludwik; Rosas-Acevedo, Hortensia

    2015-04-01

    A model for a system of a finite number of molecules in confinement is presented and expressions for determining the temperature, pressure, and volume of the system are derived. The present model is a generalisation of the Zwanzig-Langevin model because it includes pressure effects in the system. It also has general validity, preserves the ergodic hypothesis, and provides a formal framework for previous studies of hydrogen clusters in confinement. The application of the model is illustrated by an investigation of a set of prebiotic compounds exposed to varying pressure and temperature. The simulations performed within the model involve the use of a combination of molecular dynamics and density functional theory methods implemented on a computer system with a mixed CPU-GPU architecture.

  11. CFD Modeling of Helium Pressurant Effects on Cryogenic Tank Pressure Rise Rates in Normal Gravity

    NASA Technical Reports Server (NTRS)

    Grayson, Gary; Lopez, Alfredo; Chandler, Frank; Hastings, Leon; Hedayat, Ali; Brethour, James

    2007-01-01

    A recently developed computational fluid dynamics modeling capability for cryogenic tanks is used to simulate both self-pressurization from external heating and also depressurization from thermodynamic vent operation. Axisymmetric models using a modified version of the commercially available FLOW-3D software are used to simulate actual physical tests. The models assume an incompressible liquid phase with density that is a function of temperature only. A fully compressible formulation is used for the ullage gas mixture that contains both condensable vapor and a noncondensable gas component. The tests, conducted at the NASA Marshall Space Flight Center, include both liquid hydrogen and nitrogen in tanks with ullage gas mixtures of each liquid's vapor and helium. Pressure and temperature predictions from the model are compared to sensor measurements from the tests and a good agreement is achieved. This further establishes the accuracy of the developed FLOW-3D based modeling approach for cryogenic systems.

  12. Awareness and Knowledge of Cardiovascular Risk through Blood Pressure and Cholesterol Testing in College Freshmen

    ERIC Educational Resources Information Center

    Melnyk, J. A.; Panza, G.; Zaleski, A.; Taylor, B.

    2015-01-01

    Background: Cardiovascular disease (CVD) is the leading cause of death in the United States, yet knowledge of CVD risk factors is surprisingly low in college students. Purpose: The purpose of this study was to determine the effectiveness of an individualized blood pressure, cholesterol, and CVD education intervention on college freshmen. Methods:…

  13. Calibrated predictions for multivariate competing risks models.

    PubMed

    Gorfine, Malka; Hsu, Li; Zucker, David M; Parmigiani, Giovanni

    2014-04-01

    Prediction models for time-to-event data play a prominent role in assessing the individual risk of a disease, such as cancer. Accurate disease prediction models provide an efficient tool for identifying individuals at high risk, and provide the groundwork for estimating the population burden and cost of disease and for developing patient care guidelines. We focus on risk prediction of a disease in which family history is an important risk factor that reflects inherited genetic susceptibility, shared environment, and common behavior patterns. In this work family history is accommodated using frailty models, with the main novel feature being allowing for competing risks, such as other diseases or mortality. We show through a simulation study that naively treating competing risks as independent right censoring events results in non-calibrated predictions, with the expected number of events overestimated. Discrimination performance is not affected by ignoring competing risks. Our proposed prediction methodologies correctly account for competing events, are very well calibrated, and easy to implement.

  14. Model of a stationary microwave argon discharge at atmospheric pressure

    SciTech Connect

    Zhelyazkov, I.; Pencheva, M.; Benova, E.

    2008-03-19

    The many applications of microwave gas discharges at atmospheric pressure in various fields of science, technology and medicine require an adequate model of these discharges. Such a model is based on the electromagnetic wave's propagation properties and on the elementary processes in the discharge bulk. In contrast to the microwave discharges at low-gas pressures, where many elementary processes might be ignored because of their negligible contribution to the electron and heavy particle's balance equations, for such discharges at atmospheric pressure the consideration of a large number of collisional processes is mandatory. For the build of a successful discharge-column model one needs three important quantities, notably the power {theta} necessary for sustaining an electron - ion pair, electron - neutral collision frequency for momentum transfer v{sub en}, and gas temperature T{sub g}. The first two key parameters are obtained by a collisional-radiative model of the argon at atmospheric pressure, while the microwave frequency {omega}/2{pi} = 2.45 GHz, plasma column radius R, gas pressure p and gas temperature T{sub g} are fixed external parameters determined by the experimental conditions. Here, we present a model of a capillary argon microwave plasma column with a length L {approx_equal} 14 cm, sustained by wave power of 110 W - the model yields the longitudinal distributions of the plasma density, expended wave power, wave electric field magnitude, and complex wave number.

  15. Optimal Blood Pressure Goals in Patients With Hypertension at High Risk for Cardiovascular Events.

    PubMed

    Aronow, Wilbert S

    2016-01-01

    Existing epidemiologic and clinical trial data suggest that the blood pressure in patients with hypertension at high risk for cardiovascular events because of coronary artery disease, diabetes mellitus, chronic kidney disease, stroke, or heart failure should be reduced to <140/90 mm Hg in patients younger than 80 years and the systolic blood pressure be reduced to 140-145 mm Hg if tolerated in patients aged 80 years and older. Studies from patients with coronary artery disease, diabetes mellitus, chronic kidney disease, stroke, and heart failure will be discussed that support a blood pressure goal of <140/90 mm Hg in patients younger than 80 years at high risk for cardiovascular events.

  16. Computation of eigenfrequencies for equilibrium models including turbulent pressure

    NASA Astrophysics Data System (ADS)

    Sonoi, T.; Belkacem, K.; Dupret, M.-A.; Samadi, R.; Ludwig, H.-G.; Caffau, E.; Mosser, B.

    2017-03-01

    Context. The space-borne missions CoRoT and Kepler have provided a wealth of highly accurate data. However, our inability to properly model the upper-most region of solar-like stars prevents us from making the best of these observations. This problem is called "surface effect" and a key ingredient to solve it is turbulent pressure for the computation of both the equilibrium models and the oscillations. While 3D hydrodynamic simulations help to include properly the turbulent pressure in the equilibrium models, the way this surface effect is included in the computation of stellar oscillations is still subject to uncertainties. Aims: We aim at determining how to properly include the effect of turbulent pressure and its Lagrangian perturbation in the adiabatic computation of the oscillations. We also discuss the validity of the gas-gamma model and reduced gamma model approximations, which have been used to compute adiabatic oscillations of equilibrium models including turbulent pressure. Methods: We use a patched model of the Sun with an inner part constructed by a 1D stellar evolution code (CESTAM) and an outer part by the 3D hydrodynamical code (CO5BOLD). Then, the adiabatic oscillations are computed using the ADIPLS code for the gas-gamma and reduced gamma model approximations and with the MAD code imposing the adiabatic condition on an existing time-dependent convection formalism. Finally, all those results are compared to the observed solar frequencies. Results: We show that the computation of the oscillations using the time-dependent convection formalism in the adiabatic limit improves significantly the agreement with the observed frequencies compared to the gas-gamma and reduced gamma model approximations. Of the components of the perturbation of the turbulent pressure, the perturbation of the density and advection term is found to contribute most to the frequency shift. Conclusions: The turbulent pressure is certainly the dominant factor responsible for the

  17. 3He Neutron Detector Pressure Effect and Comparison to Models

    SciTech Connect

    Kouzes, Richard T.; Ely, James H.; Lintereur, Azaree T.; Siciliano, Edward R.; Stromswold, David C.; Woodring, Mitchell L.

    2010-01-14

    Reported here are the results of measurements performed to determine the efficiency of 3He filled proportional counters as a function of gas pressure in the SAIC system. Motivation for these measurements was largely to validate the current model of the SAIC system. Those predictions indicated that the neutron detection efficiency plotted as a function of pressure has a simple, logarithmic shape. As for absolute performance, the model results indicated the 3He pressure in the current SAIC system could not be reduced appreciably while meeting the current required level of detection sensitivity. Thus, saving 3He by reducing its pressure was predicted not to be a viable option in the current SAIC system.

  18. Unsteady pressure loads in a generic high speed engine model

    NASA Technical Reports Server (NTRS)

    Parrott, Tony L.; Jones, Michael G.; Thurlow, Ernie M.

    1992-01-01

    Unsteady pressure loads were measured along the top interior wall of a generic high-speed engine (GHSE) model undergoing performance tests in the combustion-Heated Scramjet Test Facility at the Langley Research Center. Flow to the model inlet was simulated at 72000 ft and a flight Mach number of 4. The inlet Mach number was 3.5 with a total temperature and pressure of 1640 R and 92 psia. The unsteady pressure loads were measured with 5 piezoresistive gages, recessed into the wall 4 to 12 gage diameters to reduce incident heat flux to the diaphragms, and distributed from the inlet to the combustor. Contributors to the unsteady pressure loads included boundary layer turbulence, combustion noise, and transients generated by unstart loads. Typical turbulent boundary layer rms pressures in the inlet ranged from 133 dB in the inlet to 181 dB in the combustor over the frequency range from 0 to 5 kHz. Downstream of the inlet exist, combustion noise was shown to dominate boundary layer turbulence noise at increased heat release rates. Noise levels in the isolator section increased by 15 dB when the fuel-air ratio was increased from 0.37 to 0.57 of the stoichiometric ratio. Transient pressure disturbances associated with engine unstarts were measured in the inlet and have an upstream propagation speed of about 7 ft/sec and pressure jumps of at least 3 psia.

  19. Risk terrain modeling predicts child maltreatment.

    PubMed

    Daley, Dyann; Bachmann, Michael; Bachmann, Brittany A; Pedigo, Christian; Bui, Minh-Thuy; Coffman, Jamye

    2016-12-01

    As indicated by research on the long-term effects of adverse childhood experiences (ACEs), maltreatment has far-reaching consequences for affected children. Effective prevention measures have been elusive, partly due to difficulty in identifying vulnerable children before they are harmed. This study employs Risk Terrain Modeling (RTM), an analysis of the cumulative effect of environmental factors thought to be conducive for child maltreatment, to create a highly accurate prediction model for future substantiated child maltreatment cases in the City of Fort Worth, Texas. The model is superior to commonly used hotspot predictions and more beneficial in aiding prevention efforts in a number of ways: 1) it identifies the highest risk areas for future instances of child maltreatment with improved precision and accuracy; 2) it aids the prioritization of risk-mitigating efforts by informing about the relative importance of the most significant contributing risk factors; 3) since predictions are modeled as a function of easily obtainable data, practitioners do not have to undergo the difficult process of obtaining official child maltreatment data to apply it; 4) the inclusion of a multitude of environmental risk factors creates a more robust model with higher predictive validity; and, 5) the model does not rely on a retrospective examination of past instances of child maltreatment, but adapts predictions to changing environmental conditions. The present study introduces and examines the predictive power of this new tool to aid prevention efforts seeking to improve the safety, health, and wellbeing of vulnerable children.

  20. Accurate pressure gradient calculations in hydrostatic atmospheric models

    NASA Technical Reports Server (NTRS)

    Carroll, John J.; Mendez-Nunez, Luis R.; Tanrikulu, Saffet

    1987-01-01

    A method for the accurate calculation of the horizontal pressure gradient acceleration in hydrostatic atmospheric models is presented which is especially useful in situations where the isothermal surfaces are not parallel to the vertical coordinate surfaces. The present method is shown to be exact if the potential temperature lapse rate is constant between the vertical pressure integration limits. The technique is applied to both the integration of the hydrostatic equation and the computation of the slope correction term in the horizontal pressure gradient. A fixed vertical grid and a dynamic grid defined by the significant levels in the vertical temperature distribution are employed.

  1. A Modified Pressure-Impulse Blast Damage Model

    DTIC Science & Technology

    1977-01-01

    rndldontffy by b!ock number) ComputerSimulation Iso -DamageModeling StructuralDamageModeling Overpressure Blast Damage ZO.ABSTRACT(==@nJ*UMr-W- ti+~f~ -fd.tuf...11 2. Pressure-Impulse Iso -Damage Model . . . . . . . . . . . . . 13 3. Representation of Youngdahl’s Model...and REPSIL Computer Codes . , . . 29 II. Single Degree-of-Freedom Iso -Damage Data . . . . . . . . 32 III. Five Degree-of-FreedomIso-Damage Data

  2. The Nursing Diagnosis of risk for pressure ulcer: content validation 1

    PubMed Central

    dos Santos, Cássia Teixeira; Almeida, Miriam de Abreu; Lucena, Amália de Fátima

    2016-01-01

    Abstract Objective: to validate the content of the new nursing diagnosis, termed risk for pressure ulcer. Method: the content validation with a sample made up of 24 nurses who were specialists in skin care from six different hospitals in the South and Southeast of Brazil. Data collection took place electronically, through an instrument constructed using the SurveyMonkey program, containing a title, definition, and 19 risk factors for the nursing diagnosis. The data were analyzed using Fehring's method and descriptive statistics. The project was approved by a Research Ethics Committee. Results: title, definition and seven risk factors were validated as "very important": physical immobilization, pressure, surface friction, shearing forces, skin moisture, alteration in sensation and malnutrition. Among the other risk factors, 11 were validated as "important": dehydration, obesity, anemia, decrease in serum albumin level, prematurity, aging, smoking, edema, impaired circulation, and decrease in oxygenation and in tissue perfusion. The risk factor of hyperthermia was discarded. Conclusion: the content validation of these components of the nursing diagnosis corroborated the importance of the same, being able to facilitate the nurse's clinical reasoning and guiding clinical practice in the preventive care for pressure ulcers. PMID:27305182

  3. Modelling Unsteady Wall Pressures Beneath Turbulent Boundary Layers

    NASA Technical Reports Server (NTRS)

    Ahn, B-K.; Graham, W. R.; Rizzi, S. A.

    2004-01-01

    As a structural entity of turbulence, hairpin vortices are believed to play a major role in developing and sustaining the turbulence process in the near wall region of turbulent boundary layers and may be regarded as the simplest conceptual model that can account for the essential features of the wall pressure fluctuations. In this work we focus on fully developed typical hairpin vortices and estimate the associated surface pressure distributions and their corresponding spectra. On the basis of the attached eddy model, we develop a representation of the overall surface pressure spectra in terms of the eddy size distribution. Instantaneous wavenumber spectra and spatial correlations are readily derivable from this representation. The model is validated by comparison of predicted wavenumber spectra and cross-correlations with existing emperical models and experimental data.

  4. Earthquake Risk Modelling - Opening the black box

    NASA Astrophysics Data System (ADS)

    Alarcon, John E.; Simic, Milan; Franco, Guillermo; Shen-Tu, Bingming

    2010-05-01

    Assessing the risk from natural catastrophes such as earthquakes involves the detailed study of the seismic sources and site conditions that contribute to the earthquake hazard in the region of interest, the distribution and particular characteristics of the exposures through the study of building stock and its vulnerabilities, and the application of specific financial terms for particular portfolios. The catastrophe modelling framework encompasses these relatively complex considerations while also including a measure of uncertainty. This paper describes succinctly the structure and modules included in a probabilistic catastrophe risk model and presents several examples of risk modelling for realistic scenarios such as the expected earthquakes in the Marmara Sea region of Turkey and the results from modelling the 2009 L'Aquila (Abruzzo) earthquake.

  5. A Risk Model for Lung Cancer Incidence

    PubMed Central

    Hoggart, Clive; Brennan, Paul; Tjonneland, Anne; Vogel, Ulla; Overvad, Kim; Østergaard, Jane Nautrup; Kaaks, Rudolf; Canzian, Federico; Boeing, Heiner; Steffen, Annika; Trichopoulou, Antonia; Bamia, Christina; Trichopoulos, Dimitrios; Johansson, Mattias; Palli, Domenico; Krogh, Vittorio; Tumino, Rosario; Sacerdote, Carlotta; Panico, Salvatore; Boshuizen, Hendriek; Bueno-de-Mesquita, H. Bas; Peeters, Petra H.M.; Lund, Eiliv; Gram, Inger Torhild; Braaten, Tonje; Rodríguez, Laudina; Agudo, Antonio; Sanchez-Cantalejo, Emilio; Arriola, Larraitz; Chirlaque, Maria-Dolores; Barricarte, Aurelio; Rasmuson, Torgny; Khaw, Kay-Tee; Wareham, Nicholas; Allen, Naomi E.; Riboli, Elio; Vineis, Paolo

    2015-01-01

    Risk models for lung cancer incidence would be useful for prioritizing individuals for screening and participation in clinical trials of chemoprevention. We present a risk model for lung cancer built using prospective cohort data from a general population which predicts individual incidence in a given time period. We build separate risk models for current and former smokers using 169,035 ever smokers from the multicenter European Prospective Investigation into Cancer and Nutrition (EPIC) and considered a model for never smokers. The data set was split into independent training and test sets. Lung cancer incidence was modeled using survival analysis, stratifying by age started smoking, and for former smokers, also smoking duration. Other risk factors considered were smoking intensity, 10 occupational/environmental exposures previously implicated with lung cancer, and single-nucleotide polymorphisms at two loci identified by genome-wide association studies of lung cancer. Individual risk in the test set was measured by the predicted probability of lung cancer incidence in the year preceding last follow-up time, predictive accuracy was measured by the area under the receiver operator characteristic curve (AUC). Using smoking information alone gave good predictive accuracy: the AUC and 95% confidence interval in ever smokers was 0.843 (0.810–0.875), the Bach model applied to the same data gave an AUC of 0.775 (0.737–0.813). Other risk factors had negligible effect on the AUC, including never smokers for whom prediction was poor. Our model is generalizable and straightforward to implement. Its accuracy can be attributed to its modeling of lifetime exposure to smoking. PMID:22496387

  6. Modeling a Transient Pressurization with Active Cooling Sizing Tool

    NASA Technical Reports Server (NTRS)

    Guzik, Monica C.; Plachta, David W.; Elchert, Justin P.

    2011-01-01

    As interest in the area of in-space zero boil-off cryogenic propellant storage develops, the need to visualize and quantify cryogen behavior during ventless tank self-pressurization and subsequent cool-down with active thermal control has become apparent. During the course of a mission, such as the launch ascent phase, there are periods that power to the active cooling system will be unavailable. In addition, because it is not feasible to install vacuum jackets on large propellant tanks, as is typically done for in-space cryogenic applications for science payloads, instances like the launch ascent heating phase are important to study. Numerous efforts have been made to characterize cryogenic tank pressurization during ventless cryogen storage without active cooling, but few tools exist to model this behavior in a user-friendly environment for general use, and none exist that quantify the marginal active cooling system size needed for power down periods to manage tank pressure response once active cooling is resumed. This paper describes the Transient pressurization with Active Cooling Tool (TACT), which is based on a ventless three-lump homogeneous thermodynamic self-pressurization model1 coupled with an active cooling system estimator. TACT has been designed to estimate the pressurization of a heated but unvented cryogenic tank, assuming an unavailable power period followed by a given cryocooler heat removal rate. By receiving input data on the tank material and geometry, propellant initial conditions, and passive and transient heating rates, a pressurization and recovery profile can be found, which establishes the time needed to return to a designated pressure. This provides the ability to understand the effect that launch ascent and unpowered mission segments have on the size of an active cooling system. A sample of the trends found show that an active cooling system sized for twice the steady state heating rate would results in a reasonable time for tank

  7. Cortisol, heart rate, and blood pressure as early markers of PTSD risk: A systematic review and meta-analysis.

    PubMed

    Morris, Matthew C; Hellman, Natalie; Abelson, James L; Rao, Uma

    2016-11-01

    Individuals with posttraumatic stress disorder (PTSD) typically exhibit altered hypothalamic-pituitary-adrenal (HPA) function and sympathetic nervous system (SNS) activity. The goals of this study were to determine whether HPA and SNS alterations in the immediate aftermath of trauma predict subsequent PTSD symptom development and whether inconsistencies observed between studies can be explained by key demographic and methodological factors. This work informs secondary prevention of PTSD by identifying subgroups of trauma survivors at risk for PTSD. This meta-analysis (26 studies, N=5186 individuals) revealed that higher heart rate measured soon after trauma exposure was associated with higher PTSD symptoms subsequently (r=0.13). Neither cortisol (r=-0.07) nor blood pressure (diastolic: r=-0.01; systolic: r=0.02) were associated with PTSD symptoms which may be influenced by methodological limitations. Associations between risk markers (heart rate, cortisol, systolic blood pressure) and PTSD symptoms were in the positive direction for younger samples and negative direction for older samples. These findings extend developmental traumatology models of PTSD by revealing an age-related shift in the presentation of early risk markers. More work will be needed to identify risk markers and pathways to PTSD while addressing methodological limitations in order to shape and target preventive interventions.

  8. Modeling conductive heat transfer during high-pressure thawing processes: determination of latent heat as a function of pressure.

    PubMed

    Denys, S; Van Loey, A M; Hendrickx, M E

    2000-01-01

    A numerical heat transfer model for predicting product temperature profiles during high-pressure thawing processes was recently proposed by the authors. In the present work, the predictive capacity of the model was considerably improved by taking into account the pressure dependence of the latent heat of the product that was used (Tylose). The effect of pressure on the latent heat of Tylose was experimentally determined by a series of freezing experiments conducted at different pressure levels. By combining a numerical heat transfer model for freezing processes with a least sum of squares optimization procedure, the corresponding latent heat at each pressure level was estimated, and the obtained pressure relation was incorporated in the original high-pressure thawing model. Excellent agreement with the experimental temperature profiles for both high-pressure freezing and thawing was observed.

  9. Exaggerated blood pressure response during the exercise treadmill test as a risk factor for hypertension

    PubMed Central

    Lima, S.G.; Albuquerque, M.F.P.M.; Oliveira, J.R.M.; Ayres, C.F.J.; Cunha, J.E.G.; Oliveira, D.F.; Lemos, R.R.; Souza, M.B.R.; Silva, O. Barbosa e

    2013-01-01

    Exaggerated blood pressure response (EBPR) during the exercise treadmill test (ETT) has been considered to be a risk factor for hypertension. The relationship of polymorphisms of the renin-angiotensin system gene with hypertension has not been established. Our objective was to evaluate whether EBPR during exercise is a clinical marker for hypertension. The study concerned a historical cohort of normotensive individuals. The exposed individuals were those who presented EBPR. At the end of the observation period (41.7 months = 3.5 years), the development of hypertension was analyzed within the two groups. Genetic polymorphisms and blood pressure behavior were assessed as independent variables, together with the classical risk factors for hypertension. The I/D gene polymorphism of the angiotensin-converting enzyme and M235T of angiotensinogen were ruled out as risk factors for hypertension. EBPR during ETT is not an independent influence on the chances of developing hypertension. No differences were observed between the hypertensive and normotensive individuals regarding gender (P = 0.655), skin color (P = 0.636), family history of hypertension (P = 0.225), diabetes mellitus (P = 0.285), or hypertriglyceridemia (P = 0.734). The risk of developing hypertension increased with increasing body mass index (BMI) and advancing age. The risk factors, which independently influenced the development of hypertension, were age and BMI. EBPR did not constitute an independent risk factor for hypertension and is probably a preclinical phase in the spectrum of normotension and hypertension. PMID:23598646

  10. Analytical model for non-thermal pressure in galaxy clusters

    NASA Astrophysics Data System (ADS)

    Shi, Xun; Komatsu, Eiichiro

    2014-07-01

    Non-thermal pressure in the intracluster gas has been found ubiquitously in numerical simulations, and observed indirectly. In this paper we develop an analytical model for intracluster non-thermal pressure in the virial region of relaxed clusters. We write down and solve a first-order differential equation describing the evolution of non-thermal velocity dispersion. This equation is based on insights gained from observations, numerical simulations, and theory of turbulence. The non-thermal energy is sourced, in a self-similar fashion, by the mass growth of clusters via mergers and accretion, and dissipates with a time-scale determined by the turnover time of the largest turbulence eddies. Our model predicts a radial profile of non-thermal pressure for relaxed clusters. The non-thermal fraction increases with radius, redshift, and cluster mass, in agreement with numerical simulations. The radial dependence is due to a rapid increase of the dissipation time-scale with radii, and the mass and redshift dependence comes from the mass growth history. Combing our model for the non-thermal fraction with the Komatsu-Seljak model for the total pressure, we obtain thermal pressure profiles, and compute the hydrostatic mass bias. We find typically 10 per cent bias for the hydrostatic mass enclosed within r500.

  11. Relationship of anthropometric indicators with blood pressure levels and the risk of hypertension in Nigerian adults

    PubMed Central

    Adedoyin, Rufus A; Mbada, Chidozie E; Bisiriyu, Luqman A; Adebayo, Rasaaq A; Balogun, Michael O; Akintomide, Anthony O

    2008-01-01

    Background and purpose: Studies on cardiovascular risks in relation to anthropometric factors are limited in Sub-Sahara Africa. The aims of this study were to examine the relationship between anthropometric parameters and blood pressure; and to evaluate body mass index (BMI) across the range of underweight and obesity as a primary risk factor of hypertension in adult Nigerians. Material and methods: 2097 adults aged between 20 and 100 years consented and participated in this door-to-door survey. All participants underwent blood pressure and anthropometric measurements using standard procedures. The population study was separated in normotensive and hypertensive males and females and the possible risk for hypertension were categorized into different classes of value based on BMI definition. Results: The relative risks (odds ratio [OR] and 95% confidence interval [CI]) of developing hypertension among the obese compared with the underweight, normal weight, and overweight persons were (OR 5.75; CI 5.67–5.83), (OR 1.73; CI 1.65–1.81), and (OR 1.54; CI 1.46–1.62) for all the participants, respectively. Among obese (BMI ≥ 30.0 Kg/m2) males, the OR for hypertension was three times (OR 2.78; CI 2.76–2.80) that of normal weight (BMI ≥ 18.5–24.9 Kg/m2) males. Females with obesity had a risk of hypertension three times (OR 3.34; CI 3.33–3.35) that of normal weight females. Conclusion: Our results indicated that the there was a significant positive correlation of obesity indicator with blood pressure. In Nigeria, we found a strong gradient between higher BMI and increased risk of hypertension among all ages. Approaches to reduce the risk of hypertension may include prevention of overweight and obesity. PMID:20428404

  12. Nursing care missed in patients at risk of or having pressure ulcers

    PubMed Central

    Valles, Jonathan Hermayn Hernández; Monsiváis, María Guadalupe Moreno; Guzmán, Ma. Guadalupe Interial; Arreola, Leticia Vázquez

    2016-01-01

    ABSTRACT Objective: to determine the nursing care missed as perceived by the nursing staff and its relation with the nursing care missed identified in the assessment of patients at risk of or having pressur ulcers. Method: descriptive correlation study. The participants were 161 nurses and 483 patients from a public hospital. The MISSCARE survey was used in combination with a Nursing Care Assessment Form for Patients at Risk of or having pressure ulcers. For the analysis, descriptive and inferential statistics were used. Results: the nursing staff indicated greater omission in skin care (38.5%), position change (31.1%) and the registration of risk factors for the development of pressure ulcers (33.5%). The nursing care missed identified in the assessment related to the use of pressure relief on bony prominences and drainage tubes interfering in the patient's movements (both with 58.6%) and the use of pneumatic mattresses (57.6%). Conclusion: a high percentage of nursing care missed was found according to the staff's perception. Nevertheless, the assessment of the nursing care missed was much higher. No significant relation was found between both. Therefore, it is a priority to reflect on the importance of objective patient assessments. PMID:27878218

  13. Development of a relative risk model for evaluating ecological risk of water environment in the Haihe River Basin estuary area.

    PubMed

    Chen, Qiuying; Liu, Jingling; Ho, Kin Chung; Yang, Zhifeng

    2012-03-15

    Ecological risk assessment for water environment is significant to water resource management of basin. Effective environmental management and systems restoration such as the Haihe River Basin require holistic understanding of the relative importance of various stressor-related impacts throughout the basin. As an effective technical tool for evaluating the ecological risk, relative risk model (RRM) was applied in regional scale successfully. In this study, the risk transfer from upstream of basin was considered and the RRM was developed through introducing the source-stressor-habitat exposure filter (SSH), the endpoint-habitat exposure filter (EH) and the stressor-endpoint effect filter (SE) to reflect the meaning of exposure and effect more explicit. Water environment which includes water quality, water quantity and aquatic ecosystems was selected as the assessment endpoints. We created a conceptual model which depicting potential and effect pathways from source to stressor to habitat to endpoint. The Haihe River Basin estuary (HRBE) was selected as the model case. The results showed that there were two low risk regions, one medium risk region and two high risk regions in the HRBE. The results also indicated that urbanization was the biggest source, the second was shipping and the third was industry, their risk scores are 5.65, 4.71 and 3.68 respectively. Furthermore, habitat destruction was the largest stressor with the risk scores (2.66), the second was oxygen consuming organic pollutants (1.75) and the third was pathogens (1.75). So these three stressors were the main influencing factors of the ecological pressure in the study area. For habitats, open waters (9.59) and intertidal mudflat were enduring the bigger pressure and should be taken considerable attention. Ecological service values damaged (30.54) and biodiversity decreased were facing the biggest risk pressure.

  14. Modeling food spoilage in microbial risk assessment.

    PubMed

    Koutsoumanis, Konstantinos

    2009-02-01

    In this study, I describe a systematic approach for modeling food spoilage in microbial risk assessment that is based on the incorporation of kinetic spoilage modeling in exposure assessment by combining data and models for the specific spoilage organisms (SSO: fraction of the total microflora responsible for spoilage) with those for pathogens. The structure of the approach is presented through an exposure assessment application for Escherichia coli O157:H7 in ground beef. The proposed approach allows for identifying spoiled products at the time of consumption by comparing the estimated level of SSO (pseudomonads) with the spoilage level (level of SSO at which spoilage is observed). The results of the application indicate that ignoring spoilage in risk assessment could lead to significant overestimations of risk.

  15. Tyre pressure monitoring using a dynamical model-based estimator

    NASA Astrophysics Data System (ADS)

    Reina, Giulio; Gentile, Angelo; Messina, Arcangelo

    2015-04-01

    In the last few years, various control systems have been investigated in the automotive field with the aim of increasing the level of safety and stability, avoid roll-over, and customise handling characteristics. One critical issue connected with their integration is the lack of state and parameter information. As an example, vehicle handling depends to a large extent on tyre inflation pressure. When inflation pressure drops, handling and comfort performance generally deteriorate. In addition, it results in an increase in fuel consumption and in a decrease in lifetime. Therefore, it is important to keep tyres within the normal inflation pressure range. This paper introduces a model-based approach to estimate online tyre inflation pressure. First, basic vertical dynamic modelling of the vehicle is discussed. Then, a parameter estimation framework for dynamic analysis is presented. Several important vehicle parameters including tyre inflation pressure can be estimated using the estimated states. This method aims to work during normal driving using information from standard sensors only. On the one hand, the driver is informed about the inflation pressure and he is warned for sudden changes. On the other hand, accurate estimation of the vehicle states is available as possible input to onboard control systems.

  16. Model-Based, Noninvasive Monitoring of Intracranial Pressure

    DTIC Science & Technology

    2013-07-01

    are twice as good as in our earlier validation studies. 15. SUBJECT TERMS Intracranial pressure (ICP), noninvasive monitoring, cerebrovascular model...of these waveforms exploits a simplified dynamic model of cerebrovascular physiology that relates the measured signals to ICP [1, 2, 3]. Validation...aggregated mechanistic model of the cerebrovascular space. Figure 2.2.1 shows successive abstractions of the relevant physiology, resulting in the circuit

  17. Control of Blood Pressure and Risk Attenuation: Post Trial Follow-Up of Randomized Groups

    PubMed Central

    Jafar, Tazeen H.; Jehan, Imtiaz; Liang, Feng; Barbier, Sylvaine; Islam, Muhammad; Bux, Rasool; Khan, Aamir Hameed; Nadkarni, Nivedita; Poulter, Neil; Chaturvedi, Nish; Ebrahim, Shah

    2015-01-01

    Background Evidence on long term effectiveness of public health strategies for lowering blood pressure (BP) is scarce. In the Control of Blood Pressure and Risk Attenuation (COBRA) Trial, a 2 x 2 factorial, cluster randomized controlled trial, the combined home health education (HHE) and trained general practitioner (GP) intervention delivered over 2 years was more effective than no intervention (usual care) in lowering systolic BP among adults with hypertension in urban Pakistan. However, it was not clear whether the effect would be sustained after the cessation of intervention. We conducted 7 years follow-up inclusive of 5 years of post intervention period of COBRA trial participants to assess the effectiveness of the interventions on BP during extended follow-up. Methods A total of 1341 individuals 40 years or older with hypertension (systolic BP 140 mm Hg or greater, diastolic BP 90 mm Hg or greater, or already receiving treatment) were followed by trained research staff masked to randomization status. BP was measured thrice with a calibrated automated device (Omron HEM-737 IntelliSense) in the sitting position after 5 minutes of rest. BP measurements were repeated after two weeks. Generalized estimating equations (GEE) were used to analyze the primary outcome of change in systolic BP from baseline to 7- year follow-up. The multivariable model was adjusted for clustering, age at baseline, sex, baseline systolic and diastolic BP, and presence of diabetes. Findings After 7 years of follow-up, systolic BP levels among those randomised to combined HHE plus trained GP intervention were significantly lower (2.1 [4.1–0.1] mm Hg) compared to those randomised to usual care, (P = 0.04). Participants receiving the combined intervention compared to usual care had a greater reduction in LDL-cholesterol (2.7 [4.8 to 0.6] mg/dl. Conclusions The benefit in systolic BP reduction observed in the original cohort assigned to the combined intervention was attenuated but still

  18. Blood Pressure and Cardiovascular Disease Risk in the Veterans Affairs Diabetes Trial

    PubMed Central

    Anderson, Robert J.; Bahn, Gideon D.; Moritz, Thomas E.; Kaufman, Derrick; Abraira, Carlos; Duckworth, William

    2011-01-01

    OBJECTIVE Blood pressure ranges associated with cardiovascular disease (CVD) events in advanced type 2 diabetes are not clear. Our objective was to determine whether baseline and follow-up (On-Study) systolic blood pressure (SBP), diastolic blood pressure (DBP), and SBP combined with DBP predict CVD events in the Veterans Affairs Diabetes Trial (VADT). RESEARCH DESIGN AND METHODS Participants in the VADT (n = 1,791) with hypertension received stepped treatment to maintain blood pressure below the target of 130/80 mmHg in standard and intensive glycemic treatment groups. Blood pressure levels of all subjects at baseline and On-Study were analyzed to detect associations with CVD risk. The primary outcome was the time from randomization to the first occurrence of myocardial infarction, stroke, congestive heart failure, surgery for vascular disease, inoperable coronary disease, amputation for ischemic gangrene, or CVD death. RESULTS Separated SBP ≥140 mmHg had significant risk at baseline (hazards ratio [HR] 1.508, P < 0.001) and On-Study (HR 1.469, P = 0.002). DBP <70 mmHg increased CVD events at baseline (HR 1.482, P < 0.001) and On-Study (HR 1.491, P < 0.001). Combined blood pressure categories indicated high risk for CVD events for SBP ≥140 with DBP <70 mmHg at baseline (HR 1.785, P = 0.03) and On-Study (HR 2.042, P = 0.003) and nearly all SBP with DBP <70 mmHg. CONCLUSIONS Increased risk of CVD events with SBP ≥140 mmHg emphasizes the urgency for treatment of systolic hypertension. Increased risk with DBP <70 mmHg, even when combined with SBP in guideline-recommended target ranges, supports a new finding in patients with type 2 diabetes. The results emphasize that DBP <70 mmHg in these patients was associated with elevated CVD risk and may best be avoided. PMID:21059830

  19. Suicide risk assessment and suicide risk formulation: essential components of the therapeutic risk management model.

    PubMed

    Silverman, Morton M

    2014-09-01

    Suicide and other suicidal behaviors are often associated with psychiatric disorders and dysfunctions. Therefore, psychiatrists have significant opportunities to identify at-risk individuals and offer treatment to reduce that risk. Although a suicide risk assessment is a core competency requirement, many clinical psychiatrists lack the requisite training and skills to appropriately assess for suicide risk. Moreover, the standard of care requires psychiatrists to foresee the possibility that a patient might engage in suicidal behavior, hence to conduct a suicide risk formulation sufficient to guide triage and treatment planning. Based on data collected via a suicide risk assessment, a suicide risk formulation is a process whereby the psychiatrist forms a judgment about a patient's foreseeable risk of suicidal behavior in order to inform triage decisions, safety and treatment planning, and interventions to reduce risk. This paper addresses the components of this process in the context of the model for therapeutic risk management of the suicidal patient developed at the Veterans Integrated Service Network (VISN) 19 Mental Illness Research, Education and Clinical Center by Wortzel et al.

  20. Modeling and Managing Risk in Billing Infrastructures

    NASA Astrophysics Data System (ADS)

    Baiardi, Fabrizio; Telmon, Claudio; Sgandurra, Daniele

    This paper discusses risk modeling and risk management in information and communications technology (ICT) systems for which the attack impact distribution is heavy tailed (e.g., power law distribution) and the average risk is unbounded. Systems with these properties include billing infrastructures used to charge customers for services they access. Attacks against billing infrastructures can be classified as peripheral attacks and backbone attacks. The goal of a peripheral attack is to tamper with user bills; a backbone attack seeks to seize control of the billing infrastructure. The probability distribution of the overall impact of an attack on a billing infrastructure also has a heavy-tailed curve. This implies that the probability of a massive impact cannot be ignored and that the average impact may be unbounded - thus, even the most expensive countermeasures would be cost effective. Consequently, the only strategy for managing risk is to increase the resilience of the infrastructure by employing redundant components.

  1. Risk management model of winter navigation operations.

    PubMed

    Valdez Banda, Osiris A; Goerlandt, Floris; Kuzmin, Vladimir; Kujala, Pentti; Montewka, Jakub

    2016-07-15

    The wintertime maritime traffic operations in the Gulf of Finland are managed through the Finnish-Swedish Winter Navigation System. This establishes the requirements and limitations for the vessels navigating when ice covers this area. During winter navigation in the Gulf of Finland, the largest risk stems from accidental ship collisions which may also trigger oil spills. In this article, a model for managing the risk of winter navigation operations is presented. The model analyses the probability of oil spills derived from collisions involving oil tanker vessels and other vessel types. The model structure is based on the steps provided in the Formal Safety Assessment (FSA) by the International Maritime Organization (IMO) and adapted into a Bayesian Network model. The results indicate that ship independent navigation and convoys are the operations with higher probability of oil spills. Minor spills are most probable, while major oil spills found very unlikely but possible.

  2. Dairy consumption, systolic blood pressure, and risk of hypertension: Mendelian randomization study.

    PubMed

    Ding, Ming; Huang, Tao; Bergholdt, Helle Km; Nordestgaard, Børge G; Ellervik, Christina; Qi, Lu

    2017-03-16

    Objective To examine whether previous observed inverse associations of dairy intake with systolic blood pressure and risk of hypertension were causal.Design Mendelian randomization study using the single nucleotide polymorphism rs4988235 related to lactase persistence as an instrumental variable.Setting CHARGE (Cohorts for Heart and Aging Research in Genomic Epidemiology) Consortium.Participants Data from 22 studies with 171 213 participants, and an additional 10 published prospective studies with 26 119 participants included in the observational analysis.Main outcome measures The instrumental variable estimation was conducted using the ratio of coefficients approach. Using meta-analysis, an additional eight published randomized clinical trials on the association of dairy consumption with systolic blood pressure were summarized.Results Compared with the CC genotype (CC is associated with complete lactase deficiency), the CT/TT genotype (TT is associated with lactose persistence, and CT is associated with certain lactase deficiency) of LCT-13910 (lactase persistence gene) rs4988235 was associated with higher dairy consumption (0.23 (about 55 g/day), 95% confidence interval 0.17 to 0.29) serving/day; P<0.001) and was not associated with systolic blood pressure (0.31, 95% confidence interval -0.05 to 0.68 mm Hg; P=0.09) or risk of hypertension (odds ratio 1.01, 95% confidence interval 0.97 to 1.05; P=0.27). Using LCT-13910 rs4988235 as the instrumental variable, genetically determined dairy consumption was not associated with systolic blood pressure (β=1.35, 95% confidence interval -0.28 to 2.97 mm Hg for each serving/day) or risk of hypertension (odds ratio 1.04, 0.88 to 1.24). Moreover, meta-analysis of the published clinical trials showed that higher dairy intake has no significant effect on change in systolic blood pressure for interventions over one month to 12 months (intervention compared with control groups: β=-0.21, 95% confidence interval -0

  3. Prevalence and risk of pressure ulcers in acute care following implementation of practice guidelines: annual pressure ulcer prevalence census 1994-2008.

    PubMed

    VanDenKerkhof, Elizabeth G; Friedberg, Elaine; Harrison, Margaret B

    2011-09-01

    Hospital-acquired pressure ulcers in the United States were estimated to cost US$2.2 to US$3.6 billion per year in 1999. In the early 1990s clinical practice guidelines for the prevention and treatment of pressure ulcers were introduced. The purpose of this study was to examine the epidemiology of pressure ulcers in acute care in Canada. The current study is based on 12,787 individuals who were inpatients during a 1-day annual census conducted in an acute care facility in Ontario between 1994 and 2008. The prevalence and incidence of pressure ulcer decreased slightly over time while the risk of pressure ulcer increased. The coccyx sacrum (~27%), heel (13%), ankle (~12%), and ischial tubersosity (~10%) were the most common ulcer sites. The implementation of clinical practice guidelines appears to have improved the quality of patient care, as demonstrated by increasing pressure ulcer risk while the prevalence and incidence of pressure ulcers has remained somewhat constant. From a policy perspective the importance of monitoring and tracking the risk and occurrence of this adverse event provides a general indicator of care, considering the many organizational aspects that may ameliorate risk.

  4. Postural effects on intracranial pressure: modeling and clinical evaluation.

    PubMed

    Qvarlander, Sara; Sundström, Nina; Malm, Jan; Eklund, Anders

    2013-11-01

    The physiological effect of posture on intracranial pressure (ICP) is not well described. This study defined and evaluated three mathematical models describing the postural effects on ICP, designed to predict ICP at different head-up tilt angles from the supine ICP value. Model I was based on a hydrostatic indifference point for the cerebrospinal fluid (CSF) system, i.e., the existence of a point in the system where pressure is independent of body position. Models II and III were based on Davson's equation for CSF absorption, which relates ICP to venous pressure, and postulated that gravitational effects within the venous system are transferred to the CSF system. Model II assumed a fully communicating venous system, and model III assumed that collapse of the jugular veins at higher tilt angles creates two separate hydrostatic compartments. Evaluation of the models was based on ICP measurements at seven tilt angles (0-71°) in 27 normal pressure hydrocephalus patients. ICP decreased with tilt angle (ANOVA: P < 0.01). The reduction was well predicted by model III (ANOVA lack-of-fit: P = 0.65), which showed excellent fit against measured ICP. Neither model I nor II adequately described the reduction in ICP (ANOVA lack-of-fit: P < 0.01). Postural changes in ICP could not be predicted based on the currently accepted theory of a hydrostatic indifference point for the CSF system, but a new model combining Davson's equation for CSF absorption and hydrostatic gradients in a collapsible venous system performed well and can be useful in future research on gravity and CSF physiology.

  5. The coefficient of restitution of pressurized balls: a mechanistic model

    NASA Astrophysics Data System (ADS)

    Georgallas, Alex; Landry, Gaëtan

    2016-01-01

    Pressurized, inflated balls used in professional sports are regulated so that their behaviour upon impact can be anticipated and allow the game to have its distinctive character. However, the dynamics governing the impacts of such balls, even on stationary hard surfaces, can be extremely complex. The energy transformations, which arise from the compression of the gas within the ball and from the shear forces associated with the deformation of the wall, are examined in this paper. We develop a simple mechanistic model of the dependence of the coefficient of restitution, e, upon both the gauge pressure, P_G, of the gas and the shear modulus, G, of the wall. The model is validated using the results from a simple series of experiments using three different sports balls. The fits to the data are extremely good for P_G > 25 kPa and consistent values are obtained for the value of G for the wall material. As far as the authors can tell, this simple, mechanistic model of the pressure dependence of the coefficient of restitution is the first in the literature. *%K Coefficient of Restitution, Dynamics, Inflated Balls, Pressure, Impact Model

  6. Validated Analytical Model of a Pressure Compensation Drip Irrigation Emitter

    NASA Astrophysics Data System (ADS)

    Shamshery, Pulkit; Wang, Ruo-Qian; Taylor, Katherine; Tran, Davis; Winter, Amos

    2015-11-01

    This work is focused on analytically characterizing the behavior of pressure-compensating drip emitters in order to design low-cost, low-power irrigation solutions appropriate for off-grid communities in developing countries. There are 2.5 billion small acreage farmers worldwide who rely solely on their land for sustenance. Drip, compared to flood, irrigation leads to up to 70% reduction in water consumption while increasing yields by 90% - important in countries like India which are quickly running out of water. To design a low-power drip system, there is a need to decrease the pumping pressure requirement at the emitters, as pumping power is the product of pressure and flow rate. To efficiently design such an emitter, the relationship between the fluid-structure interactions that occur in an emitter need to be understood. In this study, a 2D analytical model that captures the behavior of a common drip emitter was developed and validated through experiments. The effects of independently changing the channel depth, channel width, channel length and land height on the performance were studied. The model and the key parametric insights presented have the potential to be optimized in order to guide the design of low-pressure, clog-resistant, pressure-compensating emitters.

  7. A Raster Based Approach To Solar Pressure Modeling

    NASA Technical Reports Server (NTRS)

    Wright, Theodore

    2014-01-01

    The impact of photons upon a spacecraft introduces small forces and moments. The magnitude and direction of the forces depend on the material properties of the spacecraft components being illuminated. Which components are being lit depends on the orientation of the craft with respect to the Sun as well as the gimbal angles for any significant moving external parts (solar arrays, typically). Some components may shield others from the Sun.To determine solar pressure in the presence overlapping components, a 3D model can be used to determine which components are illuminated. A view (image) of the model as seen from the Sun shows the only contributors to solar pressure. This image can be decomposed into pixels, each of which can be treated as a non-overlapping flat plate as far as solar pressure calculations are concerned. The sums of the pressures and moments on these plates approximate the solar pressure and moments on the entire vehicle.The image rasterization technique can also be used to compute other spacecraft attributes that are dependent on attitude and geometry, including solar array power generation capability and free molecular flow drag.

  8. Technology for pressure-instrumented thin airfoil models

    NASA Technical Reports Server (NTRS)

    Wigley, David A.

    1988-01-01

    A novel method of airfoil model construction was developed. This Laminated Sheet technique uses 0.8 mm thick sheets of A286 containing a network of pre-formed channels which are vacuum brazed together to form the airfoil. A 6.25 percent model of the X29A canard, which has a 5 percent thick section, was built using this technique. The model contained a total of 96 pressure orifices, 56 in three chordwise rows on the upper surface and 37 in three similar rows on the lower surface. It was tested in the NASA Langley 0.3 m Transonic Cryogenic Tunnel. Unique aerodynamic data was obtained over the full range of temperature and pressure. Part of the data was at transonic Mach numbers and flight Reynolds number. A larger two dimensional model of the NACA 64a-105 airfoil section was also fabricated. Scale up presented some problems, but a testable airfoil was fabricated.

  9. High Temperature High Pressure Thermodynamic Measurements for Coal Model Compounds

    SciTech Connect

    John C. Chen; Vinayak N. Kabadi

    1998-11-12

    The overall objective of this project is to develop a better thermodynamic model for predicting properties of high-boiling coal derived liquids, especially the phase equilibria of different fractions at elevated temperatures and pressures. The development of such a model requires data on vapor-liquid equilibria (VLE), enthalpy, and heat capacity which would be experimentally determined for binary systems of coal model compounds and compiled into a database. The data will be used to refine existing models such as UNIQUAC and UNIFAC. The flow VLE apparatus designed and built for a previous project was upgraded and recalibrated for data measurements for thk project. The modifications include better and more accurate sampling technique and addition of a digital recorder to monitor temperature, pressure and liquid level inside the VLE cell. VLE data measurements for system benzene-ethylbenzene have been completed. The vapor and liquid samples were analysed using the Perkin-Elmer Autosystem gas chromatography.

  10. A Probabilistic Asteroid Impact Risk Model

    NASA Technical Reports Server (NTRS)

    Mathias, Donovan L.; Wheeler, Lorien F.; Dotson, Jessie L.

    2016-01-01

    Asteroid threat assessment requires the quantification of both the impact likelihood and resulting consequence across the range of possible events. This paper presents a probabilistic asteroid impact risk (PAIR) assessment model developed for this purpose. The model incorporates published impact frequency rates with state-of-the-art consequence assessment tools, applied within a Monte Carlo framework that generates sets of impact scenarios from uncertain parameter distributions. Explicit treatment of atmospheric entry is included to produce energy deposition rates that account for the effects of thermal ablation and object fragmentation. These energy deposition rates are used to model the resulting ground damage, and affected populations are computed for the sampled impact locations. The results for each scenario are aggregated into a distribution of potential outcomes that reflect the range of uncertain impact parameters, population densities, and strike probabilities. As an illustration of the utility of the PAIR model, the results are used to address the question of what minimum size asteroid constitutes a threat to the population. To answer this question, complete distributions of results are combined with a hypothetical risk tolerance posture to provide the minimum size, given sets of initial assumptions. Model outputs demonstrate how such questions can be answered and provide a means for interpreting the effect that input assumptions and uncertainty can have on final risk-based decisions. Model results can be used to prioritize investments to gain knowledge in critical areas or, conversely, to identify areas where additional data has little effect on the metrics of interest.

  11. Plantar Pressure as a Risk Assessment Tool for Diabetic Foot Ulceration in Egyptian Patients with Diabetes

    PubMed Central

    Fawzy, Olfat A; Arafa, Asmaa I; El Wakeel, Mervat A; Abdul Kareem, Shaimaa H

    2014-01-01

    BACKGROUND Diabetic foot ulceration is a preventable long-term complication of diabetes. In the present study, peak plantar pressures (PPP) and other characteristics were assessed in a group of 100 Egyptian patients with diabetes with or without neuropathy and foot ulcers. The aim was to study the relationship between plantar pressure (PP) and neuropathy with or without ulceration and trying to clarify the utility of pedobarography as an ulceration risk assessment tool in patients with diabetes. SUBJECTS AND METHODS A total of 100 patients having diabetes were selected. All patients had a comprehensive foot evaluation, including assessment for neuropathy using modified neuropathy disability score (MNDS), for peripheral vascular disease using ankle brachial index, and for dynamic foot pressures using the MAT system (Tekscan). The studied patients were grouped into: (1) diabetic control group (DC), which included 37 patients who had diabetes without neuropathy or ulceration and MNDS ≤2; (2) diabetic neuropathy group (DN), which included 33 patients who had diabetes with neuropathy and MNDS >2, without current or a history of ulceration; and (3) diabetic ulcer group (DU), which included 30 patients who had diabetes and current ulceration, seven of those patients also gave a history of ulceration. RESULTS PP parameters were significantly different between the studied groups, namely, forefoot peak plantar pressure (FFPPP), rearfoot peak plantar pressure (RFPPP), forefoot/rearfoot ratio (F/R), forefoot peak pressure gradient (FFPPG) rearfoot peak pressure gradient (RFPPG), and forefoot peak pressure gradient/rearfoot peak pressure gradient (FFPPG/RFPPG) (P < 0.05). FFPPP and F/R were significantly higher in the DU group compared to the DN and DC groups (P < 0.05), with no significant difference between DN and DC. FFPPG was significantly higher in the DU and DN groups compared to the DC group (P < 0.05). RFPPP and FFPPG/RFPPG were significantly higher in the DU and DN

  12. Explicit Pore Pressure Material Model in Carbon-Cloth Phenolic

    NASA Technical Reports Server (NTRS)

    Gutierrez-Lemini, Danton; Ehle, Curt

    2003-01-01

    An explicit material model that uses predicted pressure in the pores of a carbon-cloth phenolic (CCP) composite has been developed. This model is intended to be used within a finite-element model to predict phenomena specific to CCP components of solid-fuel-rocket nozzles subjected to high operating temperatures and to mechanical stresses that can be great enough to cause structural failures. Phenomena that can be predicted with the help of this model include failures of specimens in restrained-thermal-growth (RTG) tests, pocketing erosion, and ply lifting

  13. On modeling pressure diffusion in non-homogeneous shear flows

    NASA Technical Reports Server (NTRS)

    Demuren, A. O.; Rogers, M. M.; Durbin, P.; Lele, S. K.

    1996-01-01

    New models are proposed for the 'slow and 'rapid' parts of the pressure diffusive transport based on the examination of DNS databases for plane mixing layers and wakes. The model for the 'slow' part is non-local, but requires the distribution of the triple-velocity correlation as a local source. The latter can be computed accurately for the normal component from standard gradient diffusion models, but such models are inadequate for the cross component. More work is required to remedy this situation.

  14. Risk analysis: divergent models and convergent interpretations

    NASA Technical Reports Server (NTRS)

    Carnes, B. A.; Gavrilova, N.

    2001-01-01

    Material presented at a NASA-sponsored workshop on risk models for exposure conditions relevant to prolonged space flight are described in this paper. Analyses used mortality data from experiments conducted at Argonne National Laboratory on the long-term effects of external whole-body irradiation on B6CF1 mice by 60Co gamma rays and fission neutrons delivered as a single exposure or protracted over either 24 or 60 once-weekly exposures. The maximum dose considered was restricted to 1 Gy for neutrons and 10 Gy for gamma rays. Proportional hazard models were used to investigate the shape of the dose response at these lower doses for deaths caused by solid-tissue tumors and tumors of either connective or epithelial tissue origin. For protracted exposures, a significant mortality effect was detected at a neutron dose of 14 cGy and a gamma-ray dose of 3 Gy. For single exposures, radiation-induced mortality for neutrons also occurred within the range of 10-20 cGy, but dropped to 86 cGy for gamma rays. Plots of risk relative to control estimated for each observed dose gave a visual impression of nonlinearity for both neutrons and gamma rays. At least for solid-tissue tumors, male and female mortality was nearly identical for gamma-ray exposures, but mortality risks for females were higher than for males for neutron exposures. As expected, protracting the gamma-ray dose reduced mortality risks. Although curvature consistent with that observed visually could be detected by a model parameterized to detect curvature, a relative risk term containing only a simple term for total dose was usually sufficient to describe the dose response. Although detectable mortality for the three pathology end points considered typically occurred at the same level of dose, the highest risks were almost always associated with deaths caused by tumors of epithelial tissue origin.

  15. Mathematical modelling of risk reduction in reinsurance

    NASA Astrophysics Data System (ADS)

    Balashov, R. B.; Kryanev, A. V.; Sliva, D. E.

    2017-01-01

    The paper presents a mathematical model of efficient portfolio formation in the reinsurance markets. The presented approach provides the optimal ratio between the expected value of return and the risk of yield values below a certain level. The uncertainty in the return values is conditioned by use of expert evaluations and preliminary calculations, which result in expected return values and the corresponding risk levels. The proposed method allows for implementation of computationally simple schemes and algorithms for numerical calculation of the numerical structure of the efficient portfolios of reinsurance contracts of a given insurance company.

  16. Landslide risk mapping and modeling in China

    NASA Astrophysics Data System (ADS)

    Li, W.; Hong, Y.

    2015-12-01

    Under circumstances of global climate change, tectonic stress and human effect, landslides are among the most frequent and severely widespread natural hazards on Earth, as demonstrated in the World Atlas of Natural Hazards (McGuire et al., 2004). Every year, landslide activities cause serious economic loss as well as casualties (Róbert et al., 2005). How landslides can be monitored and predicted is an urgent research topic of the international landslide research community. Particularly, there is a lack of high quality and updated landslide risk maps and guidelines that can be employed to better mitigate and prevent landslide disasters in many emerging regions, including China (Hong, 2007). Since the 1950s, landslide events have been recorded in the statistical yearbooks, newspapers, and monographs in China. As disasters have been increasingly concerned by the government and the public, information about landslide events is becoming available from online news reports (Liu et al., 2012).This study presents multi-scale landslide risk mapping and modeling in China. At the national scale, based on historical data and practical experiences, we carry out landslide susceptibility and risk mapping by adopting a statistical approach and pattern recognition methods to construct empirical models. Over the identified landslide hot-spot areas, we further evaluate the slope-stability for each individual site (Sidle and Hirotaka, 2006), with the ultimate goal to set up a space-time multi-scale coupling system of Landslide risk mapping and modeling for landslide hazard monitoring and early warning.

  17. Risk management model in road transport systems

    NASA Astrophysics Data System (ADS)

    Sakhapov, R. L.; Nikolaeva, R. V.; Gatiyatullin, M. H.; Makhmutov, M. M.

    2016-08-01

    The article presents the results of a study of road safety indicators that influence the development and operation of the transport system. Road safety is considered as a continuous process of risk management. Authors constructed a model that relates the social risks of a major road safety indicator - the level of motorization. The model gives a fairly accurate assessment of the level of social risk for any given level of motorization. Authors calculated the dependence of the level of socio-economic costs of accidents and injured people in them. The applicability of the concept of socio-economic damage is caused by the presence of a linear relationship between the natural and economic indicators damage from accidents. The optimization of social risk is reduced to finding the extremum of the objective function that characterizes the economic effect of the implementation of measures to improve safety. The calculations make it possible to maximize the net present value, depending on the costs of improving road safety, taking into account socio-economic damage caused by accidents. The proposed econometric models make it possible to quantify the efficiency of the transportation system, allow to simulate the change in road safety indicators.

  18. Landslide risk models for decision making.

    PubMed

    Bonachea, Jaime; Remondo, Juan; de Terán, José Ramón Díaz; González-Díez, Alberto; Cendrero, Antonio

    2009-11-01

    This contribution presents a quantitative procedure for landslide risk analysis and zoning considering hazard, exposure (or value of elements at risk), and vulnerability. The method provides the means to obtain landslide risk models (expressing expected damage due to landslides on material elements and economic activities in monetary terms, according to different scenarios and periods) useful to identify areas where mitigation efforts will be most cost effective. It allows identifying priority areas for the implementation of actions to reduce vulnerability (elements) or hazard (processes). The procedure proposed can also be used as a preventive tool, through its application to strategic environmental impact analysis (SEIA) of land-use plans. The underlying hypothesis is that reliable predictions about hazard and risk can be made using models based on a detailed analysis of past landslide occurrences in connection with conditioning factors and data on past damage. The results show that the approach proposed and the hypothesis formulated are essentially correct, providing estimates of the order of magnitude of expected losses for a given time period. Uncertainties, strengths, and shortcomings of the procedure and results obtained are discussed and potential lines of research to improve the models are indicated. Finally, comments and suggestions are provided to generalize this type of analysis.

  19. Hydrodynamic model of advanced pressurized fluidized bed combustion

    SciTech Connect

    Horio, Masayuki; Lei, H.W.

    1997-12-31

    A hydrodynamic model was developed for the advanced pressurized fluidized bed combustion (A-PFBC) process. The particular system investigated here is composed of a pressurized circulating fluidized bed (PCFB) for coal gasification/desulfurization and a PCFB for combustion with the gas-solid counter-current flow through the two PCFBs. One of the most important parameters may be the material seal height (MSH) in the downcomer connecting the gasifier/desulfurizer and the combustor, which is thought to strongly influence the safe and stable operation of the process. In this mode, MSH was determined according to the pressure balance between the gasifier/desulfurizer and the combustor. The solid flux in the lower dense region of the two PCFBs was estimated by considering the clustering suspension and core-annulus flow. The mean cluster size and voidage in the cluster phase were predicted by the cluster size model of Horio-Ito (1996). Solid flux of the gasifier and combustor was calculated based on mass balances of limestone, char and ash in the system. Based on this model, the whole pressure profile loop in the system was predicted, and the effects of operating conditions on MSH between the gasifier and the combustor were investigated. The feasibility of the A-PCFB system with PCFBs both for the gasifier/desulfurizer and for the combustor was successfully confirmed.

  20. Modeling the pressure pulse shape of piezoelectric lithotripters

    NASA Astrophysics Data System (ADS)

    Dreyer, Thomas; Riedlinger, Rainer

    2002-11-01

    Piezoelectric focusing transducers are widely used in extracorporeal lithotripsy. To optimize the therapeutically relevant focal pressure pulse it is necessary to affect the generated pulse shape at the transducer surface. Therefore a modeling approach is required containing the acousto-mechanical properties of the transducer structure as well as the influence of the electrical drive. The procedure presented here uses three dimensional transient finite element simulations to calculate an electro-acoustical impulse response of the transducer structure and linear systems theory to model the influence of the driving circuit on the emitted acoustical signal. Applying a short electrical pulse an acoustical impulse response can be simulated under plane wave conditions, which is valid at sufficiently large distances from the transducer. Focal pressures are estimated rapidly by linear calculations or accurately by a nonlinear propagation model. The influence of electrical drive conditions on the emitted acoustical signal is investigated very efficiently by a convolution with the desired electrical input, avoiding FEM simulations for each case. Reverting this process the required driving voltage course for a given pressure signal is determined. Alterations of the pressure signal in terms of pulse width and tensile components are demonstrated theoretically, varying the design parameters of the transducer.

  1. Quantitative risk modelling for new pharmaceutical compounds.

    PubMed

    Tang, Zhengru; Taylor, Mark J; Lisboa, Paulo; Dyas, Mark

    2005-11-15

    The process of discovering and developing new drugs is long, costly and risk-laden. Faced with a wealth of newly discovered compounds, industrial scientists need to target resources carefully to discern the key attributes of a drug candidate and to make informed decisions. Here, we describe a quantitative approach to modelling the risk associated with drug development as a tool for scenario analysis concerning the probability of success of a compound as a potential pharmaceutical agent. We bring together the three strands of manufacture, clinical effectiveness and financial returns. This approach involves the application of a Bayesian Network. A simulation model is demonstrated with an implementation in MS Excel using the modelling engine Crystal Ball.

  2. Facial pressure zones of an oronasal interface for noninvasive ventilation: a computer model analysis* **

    PubMed Central

    Barros, Luana Souto; Talaia, Pedro; Drummond, Marta; Natal-Jorge, Renato

    2014-01-01

    OBJECTIVE: To study the effects of an oronasal interface (OI) for noninvasive ventilation, using a three-dimensional (3D) computational model with the ability to simulate and evaluate the main pressure zones (PZs) of the OI on the human face. METHODS: We used a 3D digital model of the human face, based on a pre-established geometric model. The model simulated soft tissues, skull, and nasal cartilage. The geometric model was obtained by 3D laser scanning and post-processed for use in the model created, with the objective of separating the cushion from the frame. A computer simulation was performed to determine the pressure required in order to create the facial PZs. We obtained descriptive graphical images of the PZs and their intensity. RESULTS: For the graphical analyses of each face-OI model pair and their respective evaluations, we ran 21 simulations. The computer model identified several high-impact PZs in the nasal bridge and paranasal regions. The variation in soft tissue depth had a direct impact on the amount of pressure applied (438-724 cmH2O). CONCLUSIONS: The computer simulation results indicate that, in patients submitted to noninvasive ventilation with an OI, the probability of skin lesion is higher in the nasal bridge and paranasal regions. This methodology could increase the applicability of biomechanical research on noninvasive ventilation interfaces, providing the information needed in order to choose the interface that best minimizes the risk of skin lesion. PMID:25610506

  3. Malignancy Risk Models for Oral Lesions

    PubMed Central

    Zarate, Ana M.; Brezzo, María M.; Secchi, Dante G.; Barra, José L.

    2013-01-01

    Objectives: The aim of this work was to assess risk habits, clinical and cellular phenotypes and TP53 DNA changes in oral mucosa samples from patients with Oral Potentially Malignant Disorders (OPMD), in order to create models that enable genotypic and phenotypic patterns to be obtained that determine the risk of lesions becoming malignant. Study Design: Clinical phenotypes, family history of cancer and risk habits were collected in clinical histories. TP53 gene mutation and morphometric-morphological features were studied, and multivariate models were applied. Three groups were estabished: a) oral cancer (OC) group (n=10), b) OPMD group (n=10), and c) control group (n=8). Results: An average of 50% of patients with malignancy were found to have smoking and drinking habits. A high percentage of TP53 mutations were observed in OC (30%) and OPMD (average 20%) lesions (p=0.000). The majority of these mutations were GC ? TA transversion mutations (60%). However, patients with OC presented mutations in all the exons and introns studied. Highest diagnostic accuracy (p=0.0001) was observed when incorporating alcohol and tobacco habits variables with TP53 mutations. Conclusions: Our results prove to be statistically reliable, with parameter estimates that are nearly unbiased even for small sample sizes. Models 2 and 3 were the most accurate for assessing the risk of an OPMD becoming cancerous. However, in a public health context, model 3 is the most recommended because the characteristics considered are easier and less costly to evaluate. Key words:TP53, oral potentially malignant disorders, risk factors, genotype, phenotype. PMID:23722122

  4. Identifying Individuals at Risk for Cardiovascular Events Across the Spectrum of Blood Pressure Levels

    PubMed Central

    Karmali, Kunal N; Ning, Hongyan; Goff, David C; Lloyd-Jones, Donald M

    2015-01-01

    Background We determined the proportion of atherosclerotic cardiovascular disease (ASCVD) events that occur across the spectrum of systolic blood pressure (SBP) and assessed whether multivariable risk assessment can identify persons who experience ASCVD events at all levels of SBP, including those with goal levels. Methods and Results Participants aged 45 to 64 years from the Framingham Offspring and Atherosclerosis Risk in Communities studies were stratified based on treated and untreated SBP levels (<120, 120 to 129, 130 to 139, 140 to 149, 150 to 159, ≥160 mm Hg). We determined the number of excess ASCVD events in each SBP stratum by calculating the difference between observed and expected events (ASCVD event rate in untreated SBP <120 mm Hg was used as the reference). We categorized participants into 10-year ASCVD risk groups using the Pooled Cohort risk equations. There were 18 898 participants (78% white; 22% black) who were followed for 10 years. We estimated 427 excess ASCVD events, of which 56% (109 of 197) and 50% (115 of 230), respectively, occurred among untreated and treated participants with elevated SBP who were not recommended for antihypertensive therapy. Among untreated participants, 10-year ASCVD risk ≥7.5% identified 64% of those who experienced an ASCVD at 10 years and 30% of those who did not. Multivariable risk assessment was less useful in baseline-treated participants. Conclusions Half of excess ASCVD events occurred in persons with elevated SBP who were not currently recommended for antihypertensive therapy. Multivariable risk assessment may help identify those likely to benefit from further risk-reducing therapies. These findings support consideration of multivariable risk in guiding prevention across the spectrum of SBP. PMID:26391134

  5. Risk assessment of physiological effects of atmospheric composition and pressure in Constellation vehicles

    NASA Astrophysics Data System (ADS)

    Scheuring, Richard; Conkin, Johnny; Jones, Jeffrey A.; Gernhardt, Michael L.

    Introduction: To limit the risk of fire and reduce denitrogenation time to prevent decompression sickness to support frequent extravehicular activities on the Moon, a hypobaric (PB=414mmHg) and mildly hypoxic ( ppO2=132mmHg, 32% O2-68%N2) living environment is considered for the Crew Exploration Vehicle (CEV) and Lunar Surface Access Module (LSAM). With acute change in ppO2 from 145-178mmHg at standard vehicular operating pressure to less than 125mmHg at desired lunar surface vehicular operating pressures, there is the possibility that some crewmembers may develop symptoms of Acute Mountain Sickness (AMS). The signs and symptoms of AMS (headache plus nausea, dizziness, fatigue, or sleeplessness) could impact crew health and performance on lunar surface missions. Methods: We performed a literature review on the topic of the physiological effects of reduced ppO2 and absolute pressure. The results of nine studies were evaluated. Results: There is evidence for an absolute pressure effect per se on AMS, so the higher the altitude for a given hypoxic alveolar oxygen (O2) partial pressure (PAO2), the greater the AMS response is. Between 7% and 25% of adults may experience mild AMS near 2000 m altitude following a rapid ascent from sea level while breathing air (6500 ft, acute PAO2=75mmHg). The operational experience with the Shuttle staged denitrogenation protocol at 528mmHg (3048 m) while breathing 26.5% O2 (acute PAO2=85mmHg) in astronauts adapting to microgravity suggests a similar likely experience in the proposed CEV environment. Conclusions: We believe the risk of mild AMS is greater given a PAO2 of 77mmHg at 4876 m altitude while breathing 32% O2 than at 1828 m altitude while breathing 21% O2. Only susceptible astronauts would develop mild and transient AMS with prolonged exposure to 414 mmHg (4876 m) while breathing 32% O2 (acute PAO2=77mmHg). So the following may be employed for operational risk reduction: (1) develop procedures to increase PB as needed in the

  6. Numerical Modeling of Pressurization of a Propellant Tank

    NASA Technical Reports Server (NTRS)

    Majumdar, Alok; Steadman, Todd

    1998-01-01

    An unsteady finite volume procedure has been developed to predict the history of pressure, temperature and mass flow rate of the pressurant and propellant during the expulsion of the propellant from a tank. The time dependent mass, momentum and energy conservation equations are solved at the ullage space. The model accounts for the change in the ullage volume due to expulsion of the propellant. It also accounts for the heat transfer from the tank wall and propellant to the ullage gas. The procedure was incorporated in the Generalized Fluid System Simulation Program (GFSSP). The results of several test cases were then compared with a published correlation of pressurant requirements for a given displacement of propellant. The agreement between the predictions and the correlation was found to be satisfactory.

  7. Numerical Modeling of Pressurization of a Propellant Tank

    NASA Technical Reports Server (NTRS)

    Majumdar, Alok; Steadman, Todd

    1999-01-01

    An unsteady finite volume procedure has been developed to predict the history o pressure, temperature and mass flow rate of the pressurant and propellant during the expulsion of the propellant from a tan. The time dependent mass, momentum and energy conservation equations are solved at the ullage space. The model accounts for the change in the ullage volume due to expulsion of the propellant. It also accounts for the heat transfer from the tank wall and propellant to the ullage gas. The procedure was incorporated in the Generalized Fluid System Simulation Program (GFSSP). The results of several test cases were then compared with a published correlation of pressurant requirements for a given displacement of propellant. The agreement between the predictions and the correlation was found to be satisfactory.

  8. A Simplified Model for Detonation Based Pressure-Gain Combustors

    NASA Technical Reports Server (NTRS)

    Paxson, Daniel E.

    2010-01-01

    A time-dependent model is presented which simulates the essential physics of a detonative or otherwise constant volume, pressure-gain combustor for gas turbine applications. The model utilizes simple, global thermodynamic relations to determine an assumed instantaneous and uniform post-combustion state in one of many envisioned tubes comprising the device. A simple, second order, non-upwinding computational fluid dynamic algorithm is then used to compute the (continuous) flowfield properties during the blowdown and refill stages of the periodic cycle which each tube undergoes. The exhausted flow is averaged to provide mixed total pressure and enthalpy which may be used as a cycle performance metric for benefits analysis. The simplicity of the model allows for nearly instantaneous results when implemented on a personal computer. The results compare favorably with higher resolution numerical codes which are more difficult to configure, and more time consuming to operate.

  9. Body forces and pressures in elastic models of the myocardium.

    PubMed Central

    Pierce, W H

    1981-01-01

    Tension strands are introduced to represent active myocardial fibers. They create one body force proportional to the divergence of the tension-direction vector, and a second equal to the tension divided by the radius of curvature. Explicit solutions to isotropic linearly elastic tensor equations with these body forces are found for the radially-symmetric, linearly-isotropic, elastic spherical heart with arbitrary radial body force. They confirm experiments showing supraluminal intramural pressures. Such pressures may affect coronary perfusion. A tension strand model which is a reasonable compromise between actual myofibrillar geometry and analytical simplicity is the iso-oblique, terminating, nonintersecting model. The body force from that or any other axially symmetric body force can be the forcing term for equations in which the heart is modeled as a thin, ellipsoidal, elastic membrane. PMID:7213931

  10. Jet fire consequence modeling for high-pressure gas pipelines

    NASA Astrophysics Data System (ADS)

    Coccorullo, Ivano; Russo, Paola

    2016-12-01

    A simple and reliable approach for sizing the hazard area potentially affected by a jet fire as consequence of the failure of high-pressure pipeline is proposed. A release rate model, taking pipeline operation properties and source release properties into account, is coupled with SLAB dispersion model and point source radiation model to calculate the hazard distance. The hazard distance is set beyond the distance at which a low chance of fatality can occur to people exposed and a wooden structure is not expected to burn due to radiation heat of jet fire. The comparison between three gases with different physico-chemical properties (i.e. natural gas, hydrogen, ethylene) is shown. The influence of pipeline operating parameters, such as: pressure, pipeline diameter and length, hole size, on the hazard area for the three gases is evaluated. Finally, a simple correlation is proposed for calculating the hazard distance as function of these parameters.

  11. Developing a pressure ulcer risk assessment scale for patients in long-term care.

    PubMed

    Lepisto, Mervi; Eriksson, Elina; Hietanen, Helvi; Lepisto, Jyri; Lauri, Sirkka

    2006-02-01

    Previous pressure ulcer risk assessment scales appear to have relied on opinions about risk factors and are based on care setting rather than research evidence. Utilizing 21 existing risk assessment scales and relevant risk factor literature, an instrument was developed by Finnish researchers that takes into account individual patient risk factors, devices and methods applied in nursing care, and organizational characteristics. The instrument underwent two pilot tests to assess the relevance and clarity of the instrument: the first involved 43 nurses and six patients; the second involved 50 nurses with expertise in wound care. Changes to questionnaire items deemed necessary as a result of descriptive analysis and agreement percentages were completed. After pilot testing, the final instrument addressed the following issues: 1) patient risks: activity, mobility in bed, mental status, nutrition, urinary incontinence, fecal incontinence, sensory perception, and skin condition; 2) devices and methods used in patient care: technical devices, bed type, mattress, overlay, seat cushions, and care methods; and 3) staff number and structure, maximum number of beds, and beds in use (the last group of questions were included to ensure participants understood the items; results were not analyzed). The phases of the study provided an expeditious means of data collection and a suitable opportunity to assess how the instrument would function in practice. Instrument reliability and validity were improved as a result of the pilot testing and can be enhanced further with continued use and assessment.

  12. Development of Relative Risk Model for Regional Groundwater Risk Assessment: A Case Study in the Lower Liaohe River Plain, China

    PubMed Central

    Li, Xianbo; Zuo, Rui; Teng, Yanguo; Wang, Jinsheng; Wang, Bin

    2015-01-01

    Increasing pressure on water supply worldwide, especially in arid areas, has resulted in groundwater overexploitation and contamination, and subsequent deterioration of the groundwater quality and threats to public health. Environmental risk assessment of regional groundwater is an important tool for groundwater protection. This study presents a new approach for assessing the environmental risk assessment of regional groundwater. It was carried out with a relative risk model (RRM) coupled with a series of indices, such as a groundwater vulnerability index, which includes receptor analysis, risk source analysis, risk exposure and hazard analysis, risk characterization, and management of groundwater. The risk map is a product of the probability of environmental contamination and impact. The reliability of the RRM was verified using Monte Carlo analysis. This approach was applied to the lower Liaohe River Plain (LLRP), northeastern China, which covers 23604 km2. A spatial analysis tool within GIS which was used to interpolate and manipulate the data to develop environmental risk maps of regional groundwater, divided the level of risk from high to low into five ranks (V, IV, III, II, I). The results indicate that areas of relative risk rank (RRR) V cover 2324 km2, covering 9.8% of the area; RRR IV covers 3986 km2, accounting for 16.9% of the area. It is a new and appropriate method for regional groundwater resource management and land use planning, and is a rapid and effective tool for improving strategic decision making to protect groundwater and reduce environmental risk. PMID:26020518

  13. Development of relative risk model for regional groundwater risk assessment: a case study in the lower Liaohe River Plain, China.

    PubMed

    Li, Xianbo; Zuo, Rui; Teng, Yanguo; Wang, Jinsheng; Wang, Bin

    2015-01-01

    Increasing pressure on water supply worldwide, especially in arid areas, has resulted in groundwater overexploitation and contamination, and subsequent deterioration of the groundwater quality and threats to public health. Environmental risk assessment of regional groundwater is an important tool for groundwater protection. This study presents a new approach for assessing the environmental risk assessment of regional groundwater. It was carried out with a relative risk model (RRM) coupled with a series of indices, such as a groundwater vulnerability index, which includes receptor analysis, risk source analysis, risk exposure and hazard analysis, risk characterization, and management of groundwater. The risk map is a product of the probability of environmental contamination and impact. The reliability of the RRM was verified using Monte Carlo analysis. This approach was applied to the lower Liaohe River Plain (LLRP), northeastern China, which covers 23604 km2. A spatial analysis tool within GIS which was used to interpolate and manipulate the data to develop environmental risk maps of regional groundwater, divided the level of risk from high to low into five ranks (V, IV, III, II, I). The results indicate that areas of relative risk rank (RRR) V cover 2324 km2, covering 9.8% of the area; RRR IV covers 3986 km2, accounting for 16.9% of the area. It is a new and appropriate method for regional groundwater resource management and land use planning, and is a rapid and effective tool for improving strategic decision making to protect groundwater and reduce environmental risk.

  14. [Baroreflex sensitivity: diagnostic importance, methods of determination and a model of baroreflex blood-pressure regulation].

    PubMed

    Svacinová, J; Moudr, J; Honzíková, N

    2013-01-01

    Baroreflex regulation of blood pressure primarily moderates its fluctuations and also affects mean blood pressure. Heart rate baroreflex sensitivity is described as changes of the inter-beat interval induced by a change of blood pressure of 1 mmHg (BRS). BRS is decreased in many cardiovascular diseases (hypertension, diabetes mellitus, obesity, cardiac failure, etc.). Decreased BRS in disposed individuals, especially after myocardial infarction, increases the risk of sudden cardiac death. Therefore, early diagnosis of BRS decrease gains in importance. This article describes different methods of determination of baroreflex sensitivity. The methods are based on evaluation of the spontaneous fluctuation of heart rate and blood pressure (spectral, sequential or nonlinear methods), or of primary changes of blood pressure induced by a vasoactive substance or a physiological manoeuvre and corresponding changes of cardiac intervals (Valsalva manoeuvre, phenylephrine administration). Each method has its advantages and disadvantages resulting from a different difficulty of calculation or from inclusion of different deviations in the results, which are not directly linked with baroreflex. Baroreflex regulating total peripheral resistance is less described. A mathematical model of baroreflex blood pressure regulation by fluctuation of heart rate and peripheral resistance is presented in this paper.

  15. Simulation Assisted Risk Assessment: Blast Overpressure Modeling

    NASA Technical Reports Server (NTRS)

    Lawrence, Scott L.; Gee, Ken; Mathias, Donovan; Olsen, Michael

    2006-01-01

    A probabilistic risk assessment (PRA) approach has been developed and applied to the risk analysis of capsule abort during ascent. The PRA is used to assist in the identification of modeling and simulation applications that can significantly impact the understanding of crew risk during this potentially dangerous maneuver. The PRA approach is also being used to identify the appropriate level of fidelity for the modeling of those critical failure modes. The Apollo launch escape system (LES) was chosen as a test problem for application of this approach. Failure modes that have been modeled and/or simulated to date include explosive overpressure-based failure, explosive fragment-based failure, land landing failures (range limits exceeded either near launch or Mode III trajectories ending on the African continent), capsule-booster re-contact during separation, and failure due to plume-induced instability. These failure modes have been investigated using analysis tools in a variety of technical disciplines at various levels of fidelity. The current paper focuses on the development and application of a blast overpressure model for the prediction of structural failure due to overpressure, including the application of high-fidelity analysis to predict near-field and headwinds effects.

  16. Quantitative Risk Modeling of Fire on the International Space Station

    NASA Technical Reports Server (NTRS)

    Castillo, Theresa; Haught, Megan

    2014-01-01

    The International Space Station (ISS) Program has worked to prevent fire events and to mitigate their impacts should they occur. Hardware is designed to reduce sources of ignition, oxygen systems are designed to control leaking, flammable materials are prevented from flying to ISS whenever possible, the crew is trained in fire response, and fire response equipment improvements are sought out and funded. Fire prevention and mitigation are a top ISS Program priority - however, programmatic resources are limited; thus, risk trades are made to ensure an adequate level of safety is maintained onboard the ISS. In support of these risk trades, the ISS Probabilistic Risk Assessment (PRA) team has modeled the likelihood of fire occurring in the ISS pressurized cabin, a phenomenological event that has never before been probabilistically modeled in a microgravity environment. This paper will discuss the genesis of the ISS PRA fire model, its enhancement in collaboration with fire experts, and the results which have informed ISS programmatic decisions and will continue to be used throughout the life of the program.

  17. Development and validation of a cardiovascular risk prediction model for Japanese: the Hisayama study.

    PubMed

    Arima, Hisatomi; Yonemoto, Koji; Doi, Yasufumi; Ninomiya, Toshiharu; Hata, Jun; Tanizaki, Yumihiro; Fukuhara, Masayo; Matsumura, Kiyoshi; Iida, Mitsuo; Kiyohara, Yutaka

    2009-12-01

    The objective of this paper is to develop a new risk prediction model of cardiovascular disease and to validate its performance in a general population of Japanese. The Hisayama study is a population-based prospective cohort study. A total of 2634 participants aged 40 years or older were followed up for 14 years for incident cardiovascular disease (stroke and coronary heart disease (myocardial infarction, coronary revascularization and sudden cardiac death)). We used data among a random two-thirds (the derivation cohort, n=1756) to develop a new risk prediction model that was then tested to compare observed and predicted outcomes in the remaining one-third (the validation cohort, n=878). A multivariable cardiovascular risk prediction model was developed that incorporated age, sex, systolic blood pressure, diabetes, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol and smoking. We assessed the performance of the model for predicting individual cardiovascular event among the validation cohort. The risk prediction model demonstrated good discrimination (c-statistic=0.81; 95% confidence interval, 0.77 to 0.86) and calibration (Hosmer-Lemeshow chi(2)-statistic=6.46; P=0.60). A simple risk score sheet based on the cardiovascular risk prediction model was also presented. We developed and validated a new cardiovascular risk prediction model in a general population of Japanese. The risk prediction model would provide a useful guide to estimate absolute risk of cardiovascular disease and to treat individual risk factors.

  18. Association of vitamin D status with arterial blood pressure and hypertension risk: a mendelian randomisation study

    PubMed Central

    Vimaleswaran, Karani S; Cavadino, Alana; Berry, Diane J; Jorde, Rolf; Dieffenbach, Aida Karina; Lu, Chen; Alves, Alexessander Couto; Heerspink, Hiddo J Lambers; Tikkanen, Emmi; Eriksson, Joel; Wong, Andrew; Mangino, Massimo; Jablonski, Kathleen A; Nolte, Ilja M; Houston, Denise K; Ahluwalia, Tarunveer Singh; van der Most, Peter J; Pasko, Dorota; Zgaga, Lina; Thiering, Elisabeth; Vitart, Veronique; Fraser, Ross M; Huffman, Jennifer E; de Boer, Rudolf A; Schöttker, Ben; Saum, Kai-Uwe; McCarthy, Mark I; Dupuis, Josée; Herzig, Karl-Heinz; Sebert, Sylvain; Pouta, Anneli; Laitinen, Jaana; Kleber, Marcus E; Navis, Gerjan; Lorentzon, Mattias; Jameson, Karen; Arden, Nigel; Cooper, Jackie A; Acharya, Jayshree; Hardy, Rebecca; Raitakari, Olli; Ripatti, Samuli; Billings, Liana K; Lahti, Jari; Osmond, Clive; Penninx, Brenda W; Rejnmark, Lars; Lohman, Kurt K; Paternoster, Lavinia; Stolk, Ronald P; Hernandez, Dena G; Byberg, Liisa; Hagström, Emil; Melhus, Håkan; Ingelsson, Erik; Mellström, Dan; Ljunggren, Östen; Tzoulaki, Ioanna; McLachlan, Stela; Theodoratou, Evropi; Tiesler, Carla M T; Jula, Antti; Navarro, Pau; Wright, Alan F; Polasek, Ozren; Hayward, Caroline; Wilson, James F; Rudan, Igor; Salomaa, Veikko; Heinrich, Joachim; Campbell, Harry; Price, Jacqueline F; Karlsson, Magnus; Lind, Lars; Michaëlsson, Karl; Bandinelli, Stefania; Frayling, Timothy M; Hartman, Catharina A; Sørensen, Thorkild I A; Kritchevsky, Stephen B; Langdahl, Bente Lomholt; Eriksson, Johan G; Florez, Jose C; Spector, Tim D; Lehtimäki, Terho; Kuh, Diana; Humphries, Steve E; Cooper, Cyrus; Ohlsson, Claes; März, Winfried; de Borst, Martin H; Kumari, Meena; Kivimaki, Mika; Wang, Thomas J; Power, Chris; Brenner, Hermann; Grimnes, Guri; van der Harst, Pim; Snieder, Harold; Hingorani, Aroon D; Pilz, Stefan; Whittaker, John C; Järvelin, Marjo-Riitta; Hyppönen, Elina

    2015-01-01

    Summary Background Low plasma 25-hydroxyvitamin D (25[OH]D) concentration is associated with high arterial blood pressure and hypertension risk, but whether this association is causal is unknown. We used a mendelian randomisation approach to test whether 25(OH)D concentration is causally associated with blood pressure and hypertension risk. Methods In this mendelian randomisation study, we generated an allele score (25[OH]D synthesis score) based on variants of genes that affect 25(OH)D synthesis or substrate availability (CYP2R1 and DHCR7), which we used as a proxy for 25(OH)D concentration. We meta-analysed data for up to 108 173 individuals from 35 studies in the D-CarDia collaboration to investigate associations between the allele score and blood pressure measurements. We complemented these analyses with previously published summary statistics from the International Consortium on Blood Pressure (ICBP), the Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE) consortium, and the Global Blood Pressure Genetics (Global BPGen) consortium. Findings In phenotypic analyses (up to n=49 363), increased 25(OH)D concentration was associated with decreased systolic blood pressure (β per 10% increase, −0·12 mm Hg, 95% CI −0·20 to −0·04; p=0·003) and reduced odds of hypertension (odds ratio [OR] 0·98, 95% CI 0·97−0·99; p=0·0003), but not with decreased diastolic blood pressure (β per 10% increase, −0·02 mm Hg, −0·08 to 0·03; p=0·37). In meta-analyses in which we combined data from D-CarDia and the ICBP (n=146 581, after exclusion of overlapping studies), each 25(OH)D-increasing allele of the synthesis score was associated with a change of −0·10 mm Hg in systolic blood pressure (−0·21 to −0·0001; p=0·0498) and a change of −0·08 mm Hg in diastolic blood pressure (−0·15 to −0·02; p=0·01). When D-CarDia and consortia data for hypertension were meta-analysed together (n=142 255), the synthesis score was associated

  19. Risk modelling for vaccination: a risk assessment perspective.

    PubMed

    Wooldridge, M

    2007-01-01

    Any risk assessment involves a number of steps. First, the risk manager, in close liaison with the risk assessor, should identify the question of interest. Then, the hazards associated with each risk question should be identified. Only then can the risks themselves be assessed. Several questions may reasonably be asked about the risk associated with avian influenza vaccines and their use. Some apply to any vaccine, while others are specific to avian influenza. Risks may occur during manufacture and during use. Some concern the vaccines themselves, while others address the effect of failure on disease control. The hazards associated with each risk question are then identified. These may be technical errors in design, development or production, such as contamination or failure to inactivate appropriately. They may relate to the biological properties of the pathogens themselves displayed during manufacture or use, for example, reversion to virulence, shedding or not being the right strain for the subsequent challenge. Following a consideration of risks and hazards, the information needed and an outline of the steps necessary to assess the risk is summarized, for an illustrative risk question using, as an example, the risks associated with the use of vaccines in the field. A brief consideration of the differences between qualitative and quantitative risk assessments is also included, and the potential effects of uncertainty and variability on the results are discussed.

  20. Risk factors correlated with risk of insulin resistance using homeostasis model assessment in adolescents in Taiwan.

    PubMed

    Lin, Shiyng-Yu; Su, Chien-Tien; Hsieh, Yi-Chen; Li, Yu-Ling; Chen, Yih-Ru; Cheng, Shu-Yun; Hu, Chien-Ming; Chen, Yi-Hua; Hsieh, Fang-I; Chiou, Hung-Yi

    2015-03-01

    The study aims to discover risk factors significantly correlated with insulin resistance among adolescents in Taiwan. A total of 339 study subjects were recruited in this cross-sectional study. A self-administered questionnaire and physical examinations including anthropometrics and biochemistry profiles were collected. Insulin resistance was assessed using homeostasis model assessment for insulin resistance (HOMA-IR). Study subjects had a significantly increased risk of IR for those with abnormal level of body mass index (odds ratio [OR] = 3.54; 95% confidence interval [CI] = 1.81-6.91), body fat (OR = 2.71; 95% CI = 1.25-5.88), and waist circumference (OR = 25.04; 95% CI = 2.93-214.14) when compared with those who have normal values. Furthermore, a significantly joint effect of 10.86-fold risk for HOMA-IR abnormality among body fat, body mass index, and systolic blood pressure was observed. The identification of risk factors significantly correlated with IR will be important to prevent metabolic syndrome-related diseases and complications for adolescents in their future life.

  1. Tantalum strength model incorporating temperature, strain rate and pressure

    NASA Astrophysics Data System (ADS)

    Lim, Hojun; Battaile, Corbett; Brown, Justin; Lane, Matt

    Tantalum is a body-centered-cubic (BCC) refractory metal that is widely used in many applications in high temperature, strain rate and pressure environments. In this work, we propose a physically-based strength model for tantalum that incorporates effects of temperature, strain rate and pressure. A constitutive model for single crystal tantalum is developed based on dislocation kink-pair theory, and calibrated to measurements on single crystal specimens. The model is then used to predict deformations of single- and polycrystalline tantalum. In addition, the proposed strength model is implemented into Sandia's ALEGRA solid dynamics code to predict plastic deformations of tantalum in engineering-scale applications at extreme conditions, e.g. Taylor impact tests and Z machine's high pressure ramp compression tests, and the results are compared with available experimental data. Sandia National Laboratories is a multi program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  2. Risk Assessment of Physiological Effects of Atmospheric Composition and Pressure in Constellation Vehicles

    NASA Technical Reports Server (NTRS)

    Scheuring, Richard A.; Conkin, Johnny; Jones, Jeffrey A.; Gernhardt, Michael L.

    2007-01-01

    To reduce denitrogenation time to prevent decompression sickness to support frequent extravehicular activities on the Moon, and to limit the risk of fire, a hypobaric (P(sub B) = 414 mmHg) and mildly hypoxic (ppO2 = 132 mmHg, 32% O2 - 68% N2) living environment is being considered during lunar missions for the Crew Exploration Vehicle (CEV) and Lunar Surface Access Module (LSAM). If the vehicular ppO2 is acutely changed from 145-178 mmHg at standard vehicular operating pressure to less than 125 mmHg at desired lunar surface outpost operating pressures, there is the possibility that some crewmembers may develop symptoms of Acute Mountain Sickness (AMS). The signs and symptoms of AMS (headache plus nausea, dizziness, fatigue, or sleeplessness), could impact crew health and performance on lunar surface missions. Methods: An exhaustive literature review on the topic of the physiological effects of reduced ppO2 and absolute pressure as may contribute to the development of hypoxia and altitude symptoms or AMS. The results of the nine most rigorous studies were collated, analyzed and contents on the physiological concerns associated with hypobaric operations, AMS and hypoxia symptoms summarized. Results: Although space vehicles have operated in hypobaric conditions previously, they have not operated in a mildly hypoxic ppO2. There is evidence for an absolute pressure effect per se on AMS, such that the higher the altitude for a given hypoxic alveolar O2 partial pressure (P(sub A)O2), the greater the likelihood of an AMS response. About 25% of adults are likely to experience mild AMS near 2,000 m (xxx mmHg) altitude following a rapid ascent from sea level while breathing air (6,500 feet, acute (P(sub A)O2) = 75 mmHg). The operational experience with the Shuttle staged denitrogenation protocol at 528 mmHg (3,048 m) while breathing 26.5% O2 (acute (P(sub A)O2) = 85 mmHg) in astronauts adapting to microgravity suggests a similar likely experience in the proposed CEV

  3. Probabilistic Seismic Risk Model for Western Balkans

    NASA Astrophysics Data System (ADS)

    Stejskal, Vladimir; Lorenzo, Francisco; Pousse, Guillaume; Radovanovic, Slavica; Pekevski, Lazo; Dojcinovski, Dragi; Lokin, Petar; Petronijevic, Mira; Sipka, Vesna

    2010-05-01

    A probabilistic seismic risk model for insurance and reinsurance purposes is presented for an area of Western Balkans, covering former Yugoslavia and Albania. This territory experienced many severe earthquakes during past centuries producing significant damage to many population centres in the region. The highest hazard is related to external Dinarides, namely to the collision zone of the Adriatic plate. The model is based on a unified catalogue for the region and a seismic source model consisting of more than 30 zones covering all the three main structural units - Southern Alps, Dinarides and the south-western margin of the Pannonian Basin. A probabilistic methodology using Monte Carlo simulation was applied to generate the hazard component of the model. Unique set of damage functions based on both loss experience and engineering assessments is used to convert the modelled ground motion severity into the monetary loss.

  4. Structural equation modeling in environmental risk assessment.

    PubMed Central

    Buncher, C R; Succop, P A; Dietrich, K N

    1991-01-01

    Environmental epidemiology requires effective models that take individual observations of environmental factors and connect them into meaningful patterns. Single-factor relationships have given way to multivariable analyses; simple additive models have been augmented by multiplicative (logistic) models. Each of these steps has produced greater enlightenment and understanding. Models that allow for factors causing outputs that can affect later outputs with putative causation working at several different time points (e.g., linkage) are not commonly used in the environmental literature. Structural equation models are a class of covariance structure models that have been used extensively in economics/business and social science but are still little used in the realm of biostatistics. Path analysis in genetic studies is one simplified form of this class of models. We have been using these models in a study of the health and development of infants who have been exposed to lead in utero and in the postnatal home environment. These models require as input the directionality of the relationship and then produce fitted models for multiple inputs causing each factor and the opportunity to have outputs serve as input variables into the next phase of the simultaneously fitted model. Some examples of these models from our research are presented to increase familiarity with this class of models. Use of these models can provide insight into the effect of changing an environmental factor when assessing risk. The usual cautions concerning believing a model, believing causation has been proven, and the assumptions that are required for each model are operative. PMID:2050063

  5. Risk-based inspection priorities for PWR high-pressure injection system components

    SciTech Connect

    Vo, T.V.; Simonen, F.A.; Phan, H.K. )

    1993-01-01

    Under U.S. Nuclear Regulatory Commission sponsorship, Pacific Northwest Laboratory developed a risk-based method that can be used to establish in-service inspection priorities for nuclear power plant components. The overall goal of this effort was to develop technical bases for improvements of inspection plans and to provide recommendations for revisions of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code, Sec. XI. The developed method used results of probabilistic risk assessment in combination with the failure modes and effects analysis (FMEA) technique to establish in-service inspection priorities for systems and components. The Surry nuclear power station, unit 1 (Surry-1) was selected for study. Inspection priorities for several pressure boundary systems at Surry-1 were determined in the early phase of the project. To complete the study, the remaining safety systems, plus balance of plant, have been analyzed; one of these is the high-pressure injection (HPI) system. This paper presents the results of inspection priorities for the HPI system.

  6. [High-grade pressure sores in frail older high-risk persons. A retrospective postmortem case-control-study].

    PubMed

    Von Renteln-Kruse, W; Krause, T; Anders, J; Kühl, M; Heinemann, A; Püschel, K

    2004-04-01

    Some old persons at risk do develop, but others, at comparable risk, do not develop high-grade pressure sores. To evaluate potentially different risk factors, we performed a post mortem case-control study in old persons who developed high-grade pressure sores within six months until 14 days before death. Consecutive cases with pressure sores grade >/=3 and potential controls at comparably high risk for pressure sores were examined before cremation. After written informed consent had been obtained by the next relatives, all available nursing and medical records of the deceased were thoroughly evaluated. Cases and controls were matched according to age, gender, immobility, and cachexia.A total of 100 cases with 71 pressure sores grade 3 and 29 pressure sores grade 4 were compared to 100 controls with 27 pressure sores grade risk as assessed by the Norton scale. The mean age was 86 years, 80% were females, 86% were bedridden, and cachexia was found in 66%. The cases were more often seriously disabled, had more often contractions of joints, and were on more drugs with intended or unwanted depressive/sedative effects (neuroleptics, benzodiazepines, centrally acting analgesics). Patient's impaired ability or low intention to comply/cooperate with preventive and/or therapeutic measures was more often recorded in cases than controls.A high degree of disablement and immobility, in particular, are risk factors for high-grade pressure sores in frail older high-risk persons. Sedative drug effects and impaired patient compliance with preventive and therapeutic measures may also be associated with the development of high-grade pressure sores in old persons at high risk.

  7. Human Plague Risk: Spatial-Temporal Models

    NASA Technical Reports Server (NTRS)

    Pinzon, Jorge E.

    2010-01-01

    This chpater reviews the use of spatial-temporal models in identifying potential risks of plague outbreaks into the human population. Using earth observations by satellites remote sensing there has been a systematic analysis and mapping of the close coupling between the vectors of the disease and climate variability. The overall result is that incidence of plague is correlated to positive El Nino/Southem Oscillation (ENSO).

  8. Risk-driven security testing using risk analysis with threat modeling approach.

    PubMed

    Palanivel, Maragathavalli; Selvadurai, Kanmani

    2014-01-01

    Security testing is a process of determining risks present in the system states and protects them from vulnerabilities. But security testing does not provide due importance to threat modeling and risk analysis simultaneously that affects confidentiality and integrity of the system. Risk analysis includes identification, evaluation and assessment of risks. Threat modeling approach is identifying threats associated with the system. Risk-driven security testing uses risk analysis results in test case identification, selection and assessment to prioritize and optimize the testing process. Threat modeling approach, STRIDE is generally used to identify both technical and non-technical threats present in the system. Thus, a security testing mechanism based on risk analysis results using STRIDE approach has been proposed for identifying highly risk states. Risk metrics considered for testing includes risk impact, risk possibility and risk threshold. Risk threshold value is directly proportional to risk impact and risk possibility. Risk-driven security testing results in reduced test suite which in turn reduces test case selection time. Risk analysis optimizes the test case selection and execution process. For experimentation, the system models namely LMS, ATM, OBS, OSS and MTRS are considered. The performance of proposed system is analyzed using Test Suite Reduction Rate (TSRR) and FSM coverage. TSRR varies from 13.16 to 21.43% whereas FSM coverage is achieved up to 91.49%. The results show that the proposed method combining risk analysis with threat modeling identifies states with high risks to improve the testing efficiency.

  9. Cognitive Modeling of Performance Response Capacity Under Time Pressure

    DTIC Science & Technology

    2010-12-31

    the risks of organizational accidents. Aldershot, UK: Ashgate. Rescorla, R. A., & Wagner, A. R. (1972). A theory of Pavlovian conditioning ... conditions . In examining the implications and limitations of this and similar applications we provide a roadmap to advance modeling and simulation of...mechanisms can be identified by this work as moderating performance under such stressed and fatigued conditions . In examining the implications and

  10. Graphical models and Bayesian domains in risk modelling: application in microbiological risk assessment.

    PubMed

    Greiner, Matthias; Smid, Joost; Havelaar, Arie H; Müller-Graf, Christine

    2013-05-15

    Quantitative microbiological risk assessment (QMRA) models are used to reflect knowledge about complex real-world scenarios for the propagation of microbiological hazards along the feed and food chain. The aim is to provide insight into interdependencies among model parameters, typically with an interest to characterise the effect of risk mitigation measures. A particular requirement is to achieve clarity about the reliability of conclusions from the model in the presence of uncertainty. To this end, Monte Carlo (MC) simulation modelling has become a standard in so-called probabilistic risk assessment. In this paper, we elaborate on the application of Bayesian computational statistics in the context of QMRA. It is useful to explore the analogy between MC modelling and Bayesian inference (BI). This pertains in particular to the procedures for deriving prior distributions for model parameters. We illustrate using a simple example that the inability to cope with feedback among model parameters is a major limitation of MC modelling. However, BI models can be easily integrated into MC modelling to overcome this limitation. We refer a BI submodel integrated into a MC model to as a "Bayes domain". We also demonstrate that an entire QMRA model can be formulated as Bayesian graphical model (BGM) and discuss the advantages of this approach. Finally, we show example graphs of MC, BI and BGM models, highlighting the similarities among the three approaches.

  11. Decreasing pressure ulcer risk during hospital procedures: a rapid process improvement workshop.

    PubMed

    Haugen, Vicki; Pechacek, Judy; Maher, Travis; Wilde, Joy; Kula, Larry; Powell, Julie

    2011-01-01

    A 300-bed acute care community hospital used a 2-day "Rapid Process Improvement Workshop" to identify factors contributing to facility-acquired pressure ulcers (PU). The Rapid Process Improvement Workshop included key stakeholders from all procedural areas providing inpatient services and used standard components of rapid process improvement: data analysis, process flow charting, factor identification, and action plan development.On day 1, the discovery process revealed increased PU risk related to prolonged immobility when transporting patients for procedures, during imaging studies, and during the perioperative period. On day 2, action plans were developed that included communication of PU risk or presence of an ulcer,measures to shorten procedure times when clinically appropriate, implementation of prevention techniques during procedures, and recommendations for mattress upgrades. In addition, educational programs about PU prevention were developed, schedules for presentations were established, and an online power point presentation was completed and placed in a learning management system module. Finally, our nursing department amended a hospital wide handoff communication tool to include skin status and PU risk level. This tool is used in all patient handoff situations, including nonnursing departments such as radiology. Patients deemed at risk for ulcers were provided "Braden Risk" armbands to enhance interdepartmental awareness.

  12. Galileo's relativity principle, the concept of pressure, and complex characteristics, for the six-equation, one-pressure model

    SciTech Connect

    Makowitz, H.

    1992-10-01

    We have studied various formulations of the concept of pressure, in the context of the usual Six-Equation Model of thermal-hydraulics. A different concept of pressure, than the usual one, has been used. This new pressure concept is Galilean Invariant, and results for the One-Pressure Model with the same complex characteristic roots as the Basic III-Posed Model,'' discussed in the literature for the cases we have investigated. We have also examined several Two-Pressure formulations and shown that two pressures are a necessary but not sufficient condition for obtaining a Well-Posed system. Several counter examples are presented. We have shown that the standard theory is not Galilean Invariant and suggested that the origin of III-Posedness is due to our closure relationships. We also question whether the current theory can satisfy conservation principles for mass, energy, and momentum.

  13. NGNP Risk Management Database: A Model for Managing Risk

    SciTech Connect

    John Collins

    2009-09-01

    To facilitate the implementation of the Risk Management Plan, the Next Generation Nuclear Plant (NGNP) Project has developed and employed an analytical software tool called the NGNP Risk Management System (RMS). A relational database developed in Microsoft® Access, the RMS provides conventional database utility including data maintenance, archiving, configuration control, and query ability. Additionally, the tool’s design provides a number of unique capabilities specifically designed to facilitate the development and execution of activities outlined in the Risk Management Plan. Specifically, the RMS provides the capability to establish the risk baseline, document and analyze the risk reduction plan, track the current risk reduction status, organize risks by reference configuration system, subsystem, and component (SSC) and Area, and increase the level of NGNP decision making.

  14. Modeling Opponents in Adversarial Risk Analysis.

    PubMed

    Rios Insua, David; Banks, David; Rios, Jesus

    2016-04-01

    Adversarial risk analysis has been introduced as a framework to deal with risks derived from intentional actions of adversaries. The analysis supports one of the decisionmakers, who must forecast the actions of the other agents. Typically, this forecast must take account of random consequences resulting from the set of selected actions. The solution requires one to model the behavior of the opponents, which entails strategic thinking. The supported agent may face different kinds of opponents, who may use different rationality paradigms, for example, the opponent may behave randomly, or seek a Nash equilibrium, or perform level-k thinking, or use mirroring, or employ prospect theory, among many other possibilities. We describe the appropriate analysis for these situations, and also show how to model the uncertainty about the rationality paradigm used by the opponent through a Bayesian model averaging approach, enabling a fully decision-theoretic solution. We also show how as we observe an opponent's decision behavior, this approach allows learning about the validity of each of the rationality models used to predict his decision by computing the models' (posterior) probabilities, which can be understood as a measure of their validity. We focus on simultaneous decision making by two agents.

  15. A model for pressurized hydrogen induced thin film blisters

    NASA Astrophysics Data System (ADS)

    van den Bos, R. A. J. M.; Reshetniak, V.; Lee, C. J.; Benschop, J.; Bijkerk, F.

    2016-12-01

    We introduce a model for hydrogen induced blister formation in nanometer thick thin films. The model assumes that molecular hydrogen gets trapped under a circular blister cap causing it to deflect elastically outward until a stable blister is formed. In the first part, the energy balance required for a stable blister is calculated. From this model, the adhesion energy of the blister cap, the internal pressure, and the critical H-dose for blister formation can be calculated. In the second part, the flux balance required for a blister to grow to a stable size is calculated. The model is applied to blisters formed in a Mo/Si multilayer after being exposed to hydrogen ions. From the model, the adhesion energy of the Mo/Si blister cap was calculated to be around 1.05 J/m2 with internal pressures in the range of 175-280 MPa. Based on the model, a minimum ion dose for the onset of blister formation was calculated to be d = 4.2 × 1018 ions/cm2. From the flux balance equations, the diffusion constant for the Mo/Si blister cap was estimated to be DH2=(10 ±1 )×10-18 cm2/s .

  16. Identity development as a buffer of adolescent risk behaviors in the context of peer group pressure and control.

    PubMed

    Dumas, Tara M; Ellis, Wendy E; Wolfe, David A

    2012-08-01

    We examined identity development as a moderator of the relation between peer group pressure and control and adolescents' engagement in risk behaviors. Participants (n=1070; M(age)=15.45 years) completed a self-report measure of identity exploration, the degree to which they have explored a variety of self-relevant values, beliefs and goals, and identity commitment, the degree to which they have secured a personal identity. Participants further reported on their frequency of risk behaviors (substance use and general deviancy) and experienced peer group pressure and control. Results confirmed that identity commitment was a buffer of substance use and identity exploration was a buffer of general deviancy in more pressuring peer groups. In more controlling peer groups, teens with greater identity commitment engaged in less risk behavior than teens with low-identity commitment. Thus, identity development may be a suitable target to deter negative effects of peer pressure in high-risk adolescents.

  17. Functional Risk Modeling for Lunar Surface Systems

    NASA Technical Reports Server (NTRS)

    Thomson, Fraser; Mathias, Donovan; Go, Susie; Nejad, Hamed

    2010-01-01

    We introduce an approach to risk modeling that we call functional modeling , which we have developed to estimate the capabilities of a lunar base. The functional model tracks the availability of functions provided by systems, in addition to the operational state of those systems constituent strings. By tracking functions, we are able to identify cases where identical functions are provided by elements (rovers, habitats, etc.) that are connected together on the lunar surface. We credit functional diversity in those cases, and in doing so compute more realistic estimates of operational mode availabilities. The functional modeling approach yields more realistic estimates of the availability of the various operational modes provided to astronauts by the ensemble of surface elements included in a lunar base architecture. By tracking functional availability the effects of diverse backup, which often exists when two or more independent elements are connected together, is properly accounted for.

  18. Models of pressure compaction and their application for wheat meal

    NASA Astrophysics Data System (ADS)

    Skonecki, Stanisław; Kulig, Ryszard; Łysiak, Grzegorz

    2014-03-01

    Processes of compaction of granular materials were described using selected models. The analysis of their accuracy on the example of wheat was the basis for the discussion on their applicability to the processing of plant-origin materials. Parameters of the model equations for wheat, compressed at 10-18% moisture content were calculated, and the relations between these parameters and wheat moisture were determined. It was found that the analyzed models described the pressure compaction of granular plant material with different accuracy, and were highly dependent on moisture. The study also indicated that the model of Ferrero et al. fits the experimental results well. The parameters of this model reflected very well the physical phenomena which occur during compression.

  19. A Spatio-temporal Model of African Animal Trypanosomosis Risk

    PubMed Central

    Dicko, Ahmadou H.; Percoma, Lassane; Sow, Adama; Adam, Yahaya; Mahama, Charles; Sidibé, Issa; Dayo, Guiguigbaza-Kossigan; Thévenon, Sophie; Fonta, William; Sanfo, Safietou; Djiteye, Aligui; Salou, Ernest; Djohan, Vincent; Cecchi, Giuliano; Bouyer, Jérémy

    2015-01-01

    Background African animal trypanosomosis (AAT) is a major constraint to sustainable development of cattle farming in sub-Saharan Africa. The habitat of the tsetse fly vector is increasingly fragmented owing to demographic pressure and shifts in climate, which leads to heterogeneous risk of cyclical transmission both in space and time. In Burkina Faso and Ghana, the most important vectors are riverine species, namely Glossina palpalis gambiensis and G. tachinoides, which are more resilient to human-induced changes than the savannah and forest species. Although many authors studied the distribution of AAT risk both in space and time, spatio-temporal models allowing predictions of it are lacking. Methodology/Principal Findings We used datasets generated by various projects, including two baseline surveys conducted in Burkina Faso and Ghana within PATTEC (Pan African Tsetse and Trypanosomosis Eradication Campaign) national initiatives. We computed the entomological inoculation rate (EIR) or tsetse challenge using a range of environmental data. The tsetse apparent density and their infection rate were separately estimated and subsequently combined to derive the EIR using a “one layer-one model” approach. The estimated EIR was then projected into suitable habitat. This risk index was finally validated against data on bovine trypanosomosis. It allowed a good prediction of the parasitological status (r2 = 67%), showed a positive correlation but less predictive power with serological status (r2 = 22%) aggregated at the village level but was not related to the illness status (r2 = 2%). Conclusions/Significance The presented spatio-temporal model provides a fine-scale picture of the dynamics of AAT risk in sub-humid areas of West Africa. The estimated EIR was high in the proximity of rivers during the dry season and more widespread during the rainy season. The present analysis is a first step in a broader framework for an efficient risk management of climate

  20. Crop yields response to water pressures in the Ebro basin in Spain: risk and water policy implications

    NASA Astrophysics Data System (ADS)

    Quiroga, S.; Fernández-Haddad, Z.; Iglesias, A.

    2011-02-01

    The increasing pressure on water systems in the Mediterranean enhances existing water conflicts and threatens water supply for agriculture. In this context, one of the main priorities for agricultural research and public policy is the adaptation of crop yields to water pressures. This paper focuses on the evaluation of hydrological risk and water policy implications for food production. Our methodological approach includes four steps. For the first step, we estimate the impacts of rainfall and irrigation water on crop yields. However, this study is not limited to general crop production functions since it also considers the linkages between those economic and biophysical aspects which may have an important effect on crop productivity. We use statistical models of yield response to address how hydrological variables affect the yield of the main Mediterranean crops in the Ebro river basin. In the second step, this study takes into consideration the effects of those interactions and analyzes gross value added sensitivity to crop production changes. We then use Montecarlo simulations to characterize crop yield risk to water variability. Finally we evaluate some policy scenarios with irrigated area adjustments that could cope in a context of increased water scarcity. A substantial decrease in irrigated land, of up to 30% of total, results in only moderate losses of crop productivity. The response is crop and region specific and may serve to prioritise adaptation strategies.

  1. Numerical Investigation of Thermal Distribution and Pressurization Behavior in Helium Pressurized Cryogenic Tank by Introducing a Multi-component Model

    NASA Astrophysics Data System (ADS)

    Lei, Wang; Yanzhong, Li; Zhan, Liu; Kang, Zhu

    An improved CFD model involving a multi-component gas mixturein the ullage is constructed to predict the pressurization behavior of a cryogenic tank considering the existence of pressurizing helium.A temperature difference between the local fluid and its saturation temperature corresponding to the vapor partial pressure is taken as the phase change driving force. As practical application of the model, hydrogen and oxygen tanks with helium pressurization arenumerically simulated by using themulti-component gas model. The results presentthat the improved model produce higher ullage temperature and pressure and lower wall temperaturethan those without multi-component consideration. The phase change has a slight influence on thepressurization performance due to the small quantities involved.

  2. Modeling Situation Awareness and Crash Risk

    PubMed Central

    Fisher, Donald L.; Strayer, David. L.

    2014-01-01

    In this article we develop a model of the relationship between crash risk and a driver’s situation awareness. We consider a driver’s situation awareness to reflect the dynamic mental model of the driving environment and to be dependent upon several psychological processes including Scanning the driving environment, Predicting and anticipating hazards, Identifying potential hazards in the driving scene as they occur, Deciding on an action, and Executing an appropriate Response (SPIDER). Together, SPIDER is important for establishing and maintaining good situation awareness of the driving environment and good situation awareness is important for coordinating and scheduling the SPIDER-relevant processes necessary for safe driving. An Order-of-Processing (OP) model makes explicit the SPIDER-relevant processes and how they predict the likelihood of a crash when the driver is or is not distracted by a secondary task. For example, the OP model shows how a small decrease in the likelihood of any particular SPIDER activity being completed successfully (because of a concurrent secondary task performance) would lead to a large increase in the relative risk of a crash. PMID:24776225

  3. 49 CFR 195.303 - Risk-based alternative to pressure testing older hazardous liquid and carbon dioxide pipelines.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... hazardous liquid and carbon dioxide pipelines. 195.303 Section 195.303 Transportation Other Regulations... Pressure Testing § 195.303 Risk-based alternative to pressure testing older hazardous liquid and carbon dioxide pipelines. (a) An operator may elect to follow a program for testing a pipeline on...

  4. 49 CFR 195.303 - Risk-based alternative to pressure testing older hazardous liquid and carbon dioxide pipelines.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... hazardous liquid and carbon dioxide pipelines. 195.303 Section 195.303 Transportation Other Regulations... Pressure Testing § 195.303 Risk-based alternative to pressure testing older hazardous liquid and carbon dioxide pipelines. (a) An operator may elect to follow a program for testing a pipeline on...

  5. 49 CFR 195.303 - Risk-based alternative to pressure testing older hazardous liquid and carbon dioxide pipelines.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... hazardous liquid and carbon dioxide pipelines. 195.303 Section 195.303 Transportation Other Regulations... Pressure Testing § 195.303 Risk-based alternative to pressure testing older hazardous liquid and carbon dioxide pipelines. (a) An operator may elect to follow a program for testing a pipeline on...

  6. 49 CFR 195.303 - Risk-based alternative to pressure testing older hazardous liquid and carbon dioxide pipelines.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... hazardous liquid and carbon dioxide pipelines. 195.303 Section 195.303 Transportation Other Regulations... Pressure Testing § 195.303 Risk-based alternative to pressure testing older hazardous liquid and carbon dioxide pipelines. (a) An operator may elect to follow a program for testing a pipeline on...

  7. HIGH TEMPERATURE HIGH PRESSURE THERMODYNAMIC MEASUREMENTS FOR COAL MODEL COMPOUNDS

    SciTech Connect

    Vinayak N. Kabadi

    1999-02-24

    The enthalpy of a fluid measured with respect to some reference temperature and pressure (enthalpy increment or Cp) is required for many engineering designs. Different techniques for determining enthalpy increments include direct measurement, integration of heat capacity as a function of temperature at constant pressure, and calculation from accurate density measurements as a function of temperature and pressure with ideal-gas enthalpies. Techniques have been developed for measurement of heat capacities using differential scanning calorimeters, but routine measurements with a precision better than 3% are rare. For thermodynamic model development, excess enthalpies or enthalpies of mixing of binary and ternary systems are generally required. Although these data can be calculated from measured values of incremental enthalpies of mixtures and corresponding pure components, the method of calculation involves subtraction of large numbers, and it is impossible to obtain accurate results from relatively accurate incremental enthalpy data. Directly measured heats of mixing provide better data for model development. In what follows, we give a brief literature survey of experimental methods available for measurement of incremental enthalpies as well as heats of mixing.

  8. Constitutive modeling of human saphenous veins at overloading pressures.

    PubMed

    Veselý, J; Horný, L; Chlup, H; Adámek, T; Krajíček, M; Žitný, R

    2015-05-01

    In the present study, inflation tests with free axial extension of 15 human vena saphena magna were conducted ex vivo to obtain data suitable for multi-axial constitutive modeling at overloading conditions (pressures up to approximately 15kPa). Subsequently the data were fitted with a hyperelastic, nonlinear and anisotropic constitutive model based on the theory of the closed thick-walled tube. It was observed that initial highly deformable behavior (up to approximately 2.5kPa) in the pressure-circumferential stretch response is followed by progressive large strain stiffening. Contrary to that, samples were much stiffer in longitudinal direction, where the observed stretches were in the range 0.98-1.03 during the entire pressurization in most cases. The effect of possible residual stress was evaluated in a simulation of the intramural stress distribution with the opening angle prescribed to 0°, 10°, 20°, 30°, 40°, and 50°. The result suggests that the optimal opening angle making the stress distribution through the wall thickness uniform is about 40°. The material parameters presented here are suitable for use in mechanobiological simulations describing the adaptation of the autologous vein wall after bypass surgery.

  9. Intracranial Aneurysm Risk Locus 5q23.2 Is Associated with Elevated Systolic Blood Pressure

    PubMed Central

    Gaál, Emília Ilona; Rehnström, Karola; Kettunen, Johannes; Sarin, Antti-Pekka; Niemelä, Mika; Jula, Antti; Raitakari, Olli T.; Lehtimäki, Terho; Eriksson, Johan G.; Widen, Elisabeth; Günel, Murat; Kurki, Mitja; von und zu Fraunberg, Mikael; Jääskeläinen, Juha E.; Hernesniemi, Juha; Järvelin, Marjo-Riitta; Pouta, Anneli; Newton-Cheh, Christopher; Salomaa, Veikko; Palotie, Aarno; Perola, Markus

    2012-01-01

    Although genome-wide association studies (GWAS) have identified hundreds of complex trait loci, the pathomechanisms of most remain elusive. Studying the genetics of risk factors predisposing to disease is an attractive approach to identify targets for functional studies. Intracranial aneurysms (IA) are rupture-prone pouches at cerebral artery branching sites. IA is a complex disease for which GWAS have identified five loci with strong association and a further 14 loci with suggestive association. To decipher potential underlying disease mechanisms, we tested whether there are IA loci that convey their effect through elevating blood pressure (BP), a strong risk factor of IA. We performed a meta-analysis of four population-based Finnish cohorts (nFIN = 11 266) not selected for IA, to assess the association of previously identified IA candidate loci (n = 19) with BP. We defined systolic BP (SBP), diastolic BP, mean arterial pressure, and pulse pressure as quantitative outcome variables. The most significant result was further tested for association in the ICBP-GWAS cohort of 200 000 individuals. We found that the suggestive IA locus at 5q23.2 in PRDM6 was significantly associated with SBP in individuals of European descent (pFIN = 3.01E-05, pICBP-GWAS = 0.0007, pALL = 8.13E-07). The risk allele of IA was associated with higher SBP. PRDM6 encodes a protein predominantly expressed in vascular smooth muscle cells. Our study connects a complex disease (IA) locus with a common risk factor for the disease (SBP). We hypothesize that common variants in PRDM6 can contribute to altered vascular wall structure, hence increasing SBP and predisposing to IA. True positive associations often fail to reach genome-wide significance in GWAS. Our findings show that analysis of traditional risk factors as intermediate phenotypes is an effective tool for deciphering hidden heritability. Further, we demonstrate that common disease loci identified in a population isolate

  10. Development of a Numerical Model of Hypervelocity Impact into a Pressurized Composite Overwrapped Pressure Vessel

    NASA Technical Reports Server (NTRS)

    Garcia, M. A.; Davis, B. A.; Miller, J. E.

    2017-01-01

    . Also seen in the figure is the eroded projectile that had passed into the COPV vessel with the generated shock wave in the pressurant propagating just ahead of the material. In this paper, pertinent experimental details and the development of the material constitutive models necessary for this work along with the efforts to validate their use are dis-cussed. The simulation results are presented and compared with the NASA experimental observations. While work is on-going from this effort, early observations pertinent to the failure threshold are presented.

  11. High hydrostatic pressure processing: a promising nonthermal technology to inactivate viruses in high-risk foods.

    PubMed

    Lou, Fangfei; Neetoo, Hudaa; Chen, Haiqiang; Li, Jianrong

    2015-01-01

    Foodborne outbreaks of viral origin have become increasingly a serious public health concern. High-pressure processing (HPP), a nonthermal technology, has come to the forefront for food processing given its minimal effects on food quality. Recent studies have revealed encouraging results for the inactivation of several human viruses by HPP. This review provides comprehensive information on the use of HPP to eliminate viruses in model systems and foods. We address the influences of various parameters, including pressure level, holding time, pH, temperature, and food matrix on the efficacy of pressure inactivation of viruses, as well as insight into the mechanisms for inactivation of enveloped and nonenveloped viruses. HPP is a promising technology for mitigating virus contamination of foods, thus it is essential to identify the optimal parameters for enhancing virus inactivation while ensuring sensory and nutritional quality retention of foods.

  12. Crystal Plasticity Model of Reactor Pressure Vessel Embrittlement in GRIZZLY

    SciTech Connect

    Chakraborty, Pritam; Biner, Suleyman Bulent; Zhang, Yongfeng; Spencer, Benjamin Whiting

    2015-07-01

    The integrity of reactor pressure vessels (RPVs) is of utmost importance to ensure safe operation of nuclear reactors under extended lifetime. Microstructure-scale models at various length and time scales, coupled concurrently or through homogenization methods, can play a crucial role in understanding and quantifying irradiation-induced defect production, growth and their influence on mechanical behavior of RPV steels. A multi-scale approach, involving atomistic, meso- and engineering-scale models, is currently being pursued within the GRIZZLY project to understand and quantify irradiation-induced embrittlement of RPV steels. Within this framework, a dislocation-density based crystal plasticity model has been developed in GRIZZLY that captures the effect of irradiation-induced defects on the flow stress behavior and is presented in this report. The present formulation accounts for the interaction between self-interstitial loops and matrix dislocations. The model predictions have been validated with experiments and dislocation dynamics simulation.

  13. Improved model for window breakdown at low pressure

    SciTech Connect

    Chang, C.; Chen, H. B.; Liu, G. Z.; Zhu, X. X.; Fang, J. Y.

    2009-03-15

    An improved global model is proposed to analyze high power microwave dielectric window breakdown at low pressure. The effect of ionization on the average momentum and energy of electrons is taken into account and a Maxwellian electron energy distribution function is adopted. The plasma energy flow and density loss to dielectric, and partially secondary electrons returning plasma to compensate the density loss, have been analytically considered. Space charge potential drop and the generalized Bohm criterion are deduced analytically. After considering the energy and density loss as well as the secondary electron compensation, the breakdown time by using numerical calculation under low pressure gets shorter compared with that under no wall loss condition. In other words, the dielectric surface breakdown time is lower than plasma volume breakdown time.

  14. Pressure ulcer prevalence, use of preventive measures, and mortality risk in an acute care population: a quality improvement project.

    PubMed

    Leijon, Siv; Bergh, Ingrid; Terstappen, Karin

    2013-01-01

    The primary aim of this quality improvement project was to determine pressure prevalence, risk of mortality, and use of preventive measures in a group of hospitalized patients. Two hundred fifty-eight patients recruited from Skaraborg Hospital in Sweden were assessed. A 1-day point prevalence study was carried out using a protocol advocated by the European PU Advisory Panel. Patients' age, gender, severity of PU (grades I-IV), anatomical location of PU, and use of preventive measures were recorded. The Swedish language version of the Modified Norton Scale was used for PU risk assessment. Data were collected by nurses trained according to the Web-based training: PU classification, "ePuclas2." After 21 months, a retrospective audit of the electronic records for patients identified with pressure ulcers was completed. The point prevalence of pressure ulcers was 23%. The total number of ulcers was 85, most were grade 1 (n = 39). The most common locations were the sacrum (n = 15) and the heel (n = 10). Three percent of patients (n = 9) had been assessed during their current hospital stay using a risk assessment tool. There was a statistically significant relationship between pressure ulcer occurrence and a low total score on the Modified Norton Scale. The patients' ages correlated significantly to the presence of a pressure ulcer. Patients with a pressure ulcer had a 3.6-fold increased risk of dying within 21 months, as compared with those without a pressure ulcer. Based on results from this quality improvement project, we recommend routine pressure ulcer risk assessment for all patients managed in a hospital setting such as ours. We further recommend that particular attention should be given to older and frail patients who are at higher risk for pressure ulcer occurrence and mortality.

  15. Modeling of Propagation of Interacting Cracks Under Hydraulic Pressure Gradient

    SciTech Connect

    Huang, Hai; Mattson, Earl Douglas; Podgorney, Robert Karl

    2015-04-01

    A robust and reliable numerical model for fracture initiation and propagation, which includes the interactions among propagating fractures and the coupling between deformation, fracturing and fluid flow in fracture apertures and in the permeable rock matrix, would be an important tool for developing a better understanding of fracturing behaviors of crystalline brittle rocks driven by thermal and (or) hydraulic pressure gradients. In this paper, we present a physics-based hydraulic fracturing simulator based on coupling a quasi-static discrete element model (DEM) for deformation and fracturing with conjugate lattice network flow model for fluid flow in both fractures and porous matrix. Fracturing is represented explicitly by removing broken bonds from the network to represent microcracks. Initiation of new microfractures and growth and coalescence of the microcracks leads to the formation of macroscopic fractures when external and/or internal loads are applied. The coupled DEM-network flow model reproduces realistic growth pattern of hydraulic fractures. In particular, simulation results of perforated horizontal wellbore clearly demonstrate that elastic interactions among multiple propagating fractures, fluid viscosity, strong coupling between fluid pressure fluctuations within fractures and fracturing, and lower length scale heterogeneities, collectively lead to complicated fracturing patterns.

  16. [Systematic pressure ulcer risk management.: Results of implementing multiple interventions at Charité-Universitätsmedizin Berlin].

    PubMed

    Hauss, Armin; Greshake, Susanne; Skiba, Thomas; Schmidt, Kristine; Rohe, Julia; Jürgensen, Jan Steffen

    2016-01-01

    Pressure ulcers impose a high burden of disease on both the affected individual and society. Demographic change and multimorbidity aggravate the problem. The present study describes the systematic implementation of a comprehensive approach to reduce the incidence of pressure ulcers in an inpatient setting. The introduction of systematic risk assessment and the subsequent risk-adjusted application of evidence-based prevention, combined with continuous feedback of outcomes as well as tailored training, were associated with a significant decline in the incidence of pressure ulcers. Especially the occurrence of high-grade ulcers could be minimized by this systems approach.

  17. Body Fatness and Risk for Elevated Blood Pressure, Total Cholesterol, and Serum Lipoprotein Ratios in Children and Adolescents.

    ERIC Educational Resources Information Center

    Williams, Daniel P.; And Others

    1992-01-01

    Examines the relationship between body fat percent and risk for elevated blood pressure, serum total cholesterol, and serum lipoprotein ratios in 1,230 African-American and 2,090 white 5-18 year olds (1,667 males and 1,653 females). Results support body fatness standards in children and adolescents as cardiovascular risk factors. (SLD)

  18. A Risk Assessment Model for Type 2 Diabetes in Chinese

    PubMed Central

    Luo, Senlin; Han, Longfei; Zeng, Ping; Chen, Feng; Pan, Limin; Wang, Shu; Zhang, Tiemei

    2014-01-01

    Aims To develop a risk assessment model for persons at risk from type 2 diabetes in Chinese. Materials and Methods The model was generated from the cross-sectional data of 16246 persons aged from 20 years old and over. C4.5 algorithm and multivariate logistic regression were used for variable selection. Relative risk value combined with expert decision constructed a comprehensive risk assessment for evaluating the individual risk category. The validity of the model was tested by cross validation and a survey performed six years later with some participants. Results Nine variables were selected as risk variables. A mathematical model was established to calculate the average probability of diabetes in each cluster's group divided by sex and age. A series of criteria combined with relative RR value (2.2) and level of risk variables stratified individuals into four risk groups (non, low, medium and high risk). The overall accuracy reached 90.99% evaluated by cross-validation inside the model population. The incidence of diabetes for each risk group increased from 1.5 (non-risk group) to 28.2(high-risk group) per one thousand persons per year with six years follow-up. Discussion The model could determine the individual risk for type 2 diabetes by four risk degrees. This model could be used as a technique tool not only to support screening persons at different risk, but also to evaluate the result of the intervention. PMID:25101994

  19. Risk Assessment of Physiological Effects of Atmospheric Composition and Pressure in Constellation Vehicles

    NASA Technical Reports Server (NTRS)

    Scheuring, Richard A.; Conkin, Johnny; Jones, J. A.; Gernhardt, M.

    2007-01-01

    To limit the risk of fire and reduce denitrogenation time to prevent decompression sickness to support frequent extravehicular activities on the Moon, a hypobaric (PB = 414 mmHg) and mildly hypoxic (ppO2 = 132 mmHg, 32% O2 - 68% N2) living environment is considered for the Crew Exploration Vehicle (CEV) and Lunar Surface Access Module (LSAM). With acute change in ppO2 from 145-178 mmHg at standard vehicular operating pressure to less than 125 mmHg at desired lunar surface vehicular operating pressures, there is the possibility that some crewmembers may develop symptoms of Acute Mountain Sickness (AMS). The signs and symptoms of AMS (headache plus nausea, dizziness, fatigue, or sleeplessness), could impact crew health and performance on lunar surface missions. An exhaustive literature review on the topic of the physiological effects of reduced ppO2 and absolute pressure as may contribute to the development of altitude symptoms or AMS was performed. The results of the nine most rigorous studies were collated, analyzed and contents on AMS and hypoxia symptoms summarized. There is evidence for an absolute pressure effect per se on AMS, so the higher the altitude for a given hypoxic alveolar O2 partial pressure (PAO2), the greater the AMS response. About 25% of adults are likely to experience mild AMS near 2,000 m altitude following a rapid ascent from sea level while breathing air (6,500 feet, acute PAO2 = 75 mmHg). The operational experience with the Shuttle staged denitrogenation protocol at 528 mmHg (3,048 m) while breathing 26.5% O2 (acute PAO2 = 85 mmHg) in astronauts adapting to microgravity suggests a similar likely experience in the proposed CEV environment. We believe the risk of mild AMS is greater given a PAO2 of 77 mmHg at 4,876 m altitude while breathing 32% O2 than at 1,828 m altitude while breathing 21% O2. Only susceptible astronauts would develop mild and transient AMS with prolonged exposure to 414 mmHg (4,876 m) while breathing 32% O2 (acute PAO2

  20. Cerebral perfusion pressure and risk of brain hypoxia in severe head injury: a prospective observational study

    PubMed Central

    Marín-Caballos, Antonio J; Murillo-Cabezas, Francisco; Cayuela-Domínguez, Aurelio; Domínguez-Roldán, Jose M; Rincón-Ferrari, M Dolores; Valencia-Anguita, Julio; Flores-Cordero, Juan M; Muñoz-Sánchez, M Angeles

    2005-01-01

    Introduction Higher and lower cerebral perfusion pressure (CPP) thresholds have been proposed to improve brain tissue oxygen pressure (PtiO2) and outcome. We study the distribution of hypoxic PtiO2 samples at different CPP thresholds, using prospective multimodality monitoring in patients with severe traumatic brain injury. Methods This is a prospective observational study of 22 severely head injured patients admitted to a neurosurgical critical care unit from whom multimodality data was collected during standard management directed at improving intracranial pressure, CPP and PtiO2. Local PtiO2 was continuously measured in uninjured areas and snapshot samples were collected hourly and analyzed in relation to simultaneous CPP. Other variables that influence tissue oxygen availability, mainly arterial oxygen saturation, end tidal carbon dioxide, body temperature and effective hemoglobin, were also monitored to keep them stable in order to avoid non-ischemic hypoxia. Results Our main results indicate that half of PtiO2 samples were at risk of hypoxia (defined by a PtiO2 equal to or less than 15 mmHg) when CPP was below 60 mmHg, and that this percentage decreased to 25% and 10% when CPP was between 60 and 70 mmHg and above 70 mmHg, respectively (p < 0.01). Conclusion Our study indicates that the risk of brain tissue hypoxia in severely head injured patients could be really high when CPP is below the normally recommended threshold of 60 mmHg, is still elevated when CPP is slightly over it, but decreases at CPP values above it. PMID:16356218

  1. Blood pressure categories and long-term risk of cardiovascular disease according to age group in Japanese men and women.

    PubMed

    Fujiyoshi, Akira; Ohkubo, Takayoshi; Miura, Katsuyuki; Murakami, Yoshitaka; Nagasawa, Shin-Ya; Okamura, Tomonori; Ueshima, Hirotsugu

    2012-09-01

    Blood pressure (BP) categories defined by systolic BP (SBP) and diastolic BP (DBP) are commonly used. However, the BP category-specific risk of cardiovascular disease (CVD) has not been thoroughly investigated in different age groups. The aim of this study was to assess long-term CVD risk and its impact according to BP categories and age group. Pooling individual data from 10 cohorts, we studied 67 309 Japanese individuals (40-89 years old) who were free of CVD at baseline: we categorized them as belonging to three age groups: 'middle-aged' (40-64 years), 'elderly' (65-74 years) and 'very elderly' (75-89 years). BP was classified according to the 2009 Japanese Society of Hypertension Guidelines. Cox models were used to estimate adjusted hazard ratios for CVD deaths. We observed 1944 CVD deaths over a mean follow-up of 10.2 years. In all age groups, the overall relationship between BP category and CVD risk was positive, with a greater strength observed for younger age groups. We observed a trend of increased risk from SBP/DBP ≥ 130/85 mm Hg in the very elderly, and a significant increase from SBP/DBP ≥ 120/80 mm Hg in the other age groups. The population attributable fractions (PAFs) of CVD death in reference to the SBP/DBP<120/80 mm Hg category ranged from 23.4% in the very elderly to 60.3% in the middle-aged. We found an overall graded increase in CVD risk with higher BP category in the very elderly. The PAFs suggest that keeping BP levels low is an important strategy for primary CVD prevention, even in an elderly population.

  2. HIGH TEMPERATURE HIGH PRESSURE THERMODYNAMIC MEASUREMENTS FOR COAL MODEL COMPOUNDS

    SciTech Connect

    Vinayak N. Kabadi

    1999-02-20

    It is well known that the fluid phase equilibria can be represented by a number of {gamma}-models , but unfortunately most of them do not function well under high temperature. In this calculation, we mainly investigate the performance of UNIQUAC and NRTL models under high temperature, using temperature dependent parameters rather than using the original formulas. the other feature of this calculation is that we try to relate the excess Gibbs energy G{sup E}and enthalpy of mixing H{sup E}simultaneously. In other words, we will use the high temperature and pressure G{sup E} and H{sup E}data to regress the temperature dependant parameters to find out which model and what kind of temperature dependant parameters should be used.

  3. Aspects of Mathematical Modelling of Pressure Retarded Osmosis.

    PubMed

    Anissimov, Yuri G

    2016-02-03

    In power generating terms, a pressure retarded osmosis (PRO) energy generating plant, on a river entering a sea or ocean, is equivalent to a hydroelectric dam with a height of about 60 meters. Therefore, PRO can add significantly to existing renewable power generation capacity if economical constrains of the method are resolved. PRO energy generation relies on a semipermeable membrane that is permeable to water and impermeable to salt. Mathematical modelling plays an important part in understanding flows of water and salt near and across semipermeable membranes and helps to optimize PRO energy generation. Therefore, the modelling can help realizing PRO energy generation potential. In this work, a few aspects of mathematical modelling of the PRO process are reviewed and discussed.

  4. Aspects of Mathematical Modelling of Pressure Retarded Osmosis

    PubMed Central

    Anissimov, Yuri G.

    2016-01-01

    In power generating terms, a pressure retarded osmosis (PRO) energy generating plant, on a river entering a sea or ocean, is equivalent to a hydroelectric dam with a height of about 60 meters. Therefore, PRO can add significantly to existing renewable power generation capacity if economical constrains of the method are resolved. PRO energy generation relies on a semipermeable membrane that is permeable to water and impermeable to salt. Mathematical modelling plays an important part in understanding flows of water and salt near and across semipermeable membranes and helps to optimize PRO energy generation. Therefore, the modelling can help realizing PRO energy generation potential. In this work, a few aspects of mathematical modelling of the PRO process are reviewed and discussed. PMID:26848696

  5. A Risk Management Model for the Federal Acquisition Process.

    DTIC Science & Technology

    1999-06-01

    risk management in the acquisition process. This research explains the Federal Acquisition Process and each of the 78 tasks to be completed by the CO...and examines the concepts of risk and risk management . This research culminates in the development of a model that identifies prevalent risks in the...contracting professionals is used to gather opinions, ideas, and practical applications of risk management in the acquisition process, and refine the model

  6. Raster-Based Approach to Solar Pressure Modeling

    NASA Technical Reports Server (NTRS)

    Wright, Theodore W. II

    2013-01-01

    An algorithm has been developed to take advantage of the graphics processing hardware in modern computers to efficiently compute high-fidelity solar pressure forces and torques on spacecraft, taking into account the possibility of self-shading due to the articulation of spacecraft components such as solar arrays. The process is easily extended to compute other results that depend on three-dimensional attitude analysis, such as solar array power generation or free molecular flow drag. The impact of photons upon a spacecraft introduces small forces and moments. The magnitude and direction of the forces depend on the material properties of the spacecraft components being illuminated. The parts of the components being lit depends on the orientation of the craft with respect to the Sun, as well as the gimbal angles for any significant moving external parts (solar arrays, typically). Some components may shield others from the Sun. The purpose of this innovation is to enable high-fidelity computation of solar pressure and power generation effects of illuminated portions of spacecraft, taking self-shading from spacecraft attitude and movable components into account. The key idea in this innovation is to compute results dependent upon complicated geometry by using an image to break the problem into thousands or millions of sub-problems with simple geometry, and then the results from the simpler problems are combined to give high-fidelity results for the full geometry. This process is performed by constructing a 3D model of a spacecraft using an appropriate computer language (OpenGL), and running that model on a modern computer's 3D accelerated video processor. This quickly and accurately generates a view of the model (as shown on a computer screen) that takes rotation and articulation of spacecraft components into account. When this view is interpreted as the spacecraft as seen by the Sun, then only the portions of the craft visible in the view are illuminated. The view as

  7. Circumferential pressure distributions in a model labyrinth seal

    NASA Technical Reports Server (NTRS)

    Leong, Y. M. M. S.; Brown, R. D.

    1982-01-01

    A research program to isolate and study leakage flow through labyrinth glands was initiated. Circumferential pressure distributions were measured in the labyrinth glands with geometry appropriate to the high pressure labyrinths in large steam turbines. Knowledge of this pressure distribution is essential as it is this unequal pressure field that results in the destabilizing force. Parameters that are likely to affect the pressure distributions are incorporated into the test rig. Some preliminary pressure profiles are presented.

  8. Prevalence and control of high blood pressure in primary care: results from the German Metabolic and Cardiovascular Risk Study (GEMCAS).

    PubMed

    Balijepalli, Chakrapani; Bramlage, Peter; Lösch, Christian; Zemmrich, Claudia; Humphries, Karin H; Moebus, Susanne

    2014-06-01

    Contemporary epidemiological data on blood pressure readings, hypertension prevalence and control in unselected patient populations covering a broad age range are scarce. The aim here is to report the prevalence of high blood pressure and to identify factors associated with blood pressure control in a large German primary care sample. We used data from the German Metabolic and Cardiovascular Risk Study including 35 869 patients aged 18-99 years. High blood pressure was defined as systolic blood pressure ≥140 mm Hg and/or diastolic blood pressure ≥90 mm Hg or using antihypertensive therapy. Factors associated with blood pressure control among patients receiving antihypertensive therapy were examined using multiple logistic regressions to estimate odds ratios and 95% confidence intervals. The prevalence of high blood pressure, uncontrolled high blood pressure and untreated high blood pressure was 54.8%, 21.3% and 17.6%, respectively. Age >50 years (1.52; 1.40-1.65), male sex (1.30; 1.20-1.41), elevated waist circumference (1.55; 1.45-1.65), high cholesterol (1.24; 1.16-1.33), high triglycerides (1.11; 1.04-1.19) and concomitant diabetes (1.29; 1.20-1.40) were independently associated with uncontrolled high blood pressure. In a majority of patients we observed hypertension despite treatment for high blood pressures. Studies examining the reasons for treatment failure are highly warranted.

  9. Invasively Measured Aortic Systolic Blood Pressure and Office Systolic Blood Pressure in Cardiovascular Risk Assessment: A Prospective Cohort Study.

    PubMed

    Laugesen, Esben; Knudsen, Søren T; Hansen, Klavs W; Rossen, Niklas B; Jensen, Lisette Okkels; Hansen, Michael G; Munkholm, Henrik; Thomsen, Kristian K; Søndergaard, Hanne; Bøttcher, Morten; Raungaard, Bent; Madsen, Morten; Hulman, Adam; Witte, Daniel; Bøtker, Hans Erik; Poulsen, Per L

    2016-09-01

    Aortic systolic blood pressure (BP) represents the hemodynamic cardiac and cerebral burden more directly than office systolic BP. Whether invasively measured aortic systolic BP confers additional prognostic value beyond office BP remains debated. In this study, office systolic BP and invasively measured aortic systolic BP were recorded in 21 908 patients (mean age: 63 years; 58% men; 14% with diabetes mellitus) with stable angina pectoris undergoing elective coronary angiography during January 2001 to December 2012. Multivariate Cox models were used to assess the association with incident myocardial infarction, stroke, and death. Discrimination and reclassification were assessed using Harrell's C and the Continuous Net Reclassification Index. Data were analyzed with and without stratification by diabetes mellitus status. During a median follow-up period of 3.7 years (range: 0.1-10.8 years), 422 strokes, 511 myocardial infarctions, and 1530 deaths occurred. Both office and aortic systolic BP were associated with stroke in patients with diabetes mellitus (hazard ratio per 10 mm Hg, 1.18 [95% confidence interval, 1.07-1.30] and 1.14 [95% confidence interval, 1.05-1.24], respectively) and with myocardial infarction in patients without diabetes mellitus (hazard ratio, 1.07 [95% confidence interval, 1.02-1.12] and 1.05 [95% confidence interval, 1.01-1.10], respectively). In models including both BP measurements, aortic BP lost statistical significance and aortic BP did not confer improvement in either C-statistics or net reclassification analysis. In conclusion, invasively measured aortic systolic BP does not add prognostic information about cardiovascular outcomes and all-cause mortality compared with office BP in patients with stable angina pectoris, either with or without diabetes mellitus.

  10. Integrating Professional and Folk Models of HIV Risk: YMSM's Perceptions of High-Risk Sex

    ERIC Educational Resources Information Center

    Kubicek, Katrina; Carpineto, Julie; McDavitt, Bryce; Weiss, George; Iverson, Ellen F.; Au, Chi-Wai; Kerrone, Dustin; Martinez, Miguel; Kipke, Michele D.

    2008-01-01

    Risks associated with HIV are well documented in research literature. Although a great deal has been written about high-risk sex, little research has been conducted to examine how young men who have sex with men (YMSM) perceive and define high-risk sexual behavior. In this study, we compare the "professional" and "folk" models of HIV risk based on…

  11. Modeling of patient's blood pressure variation during ambulance transportation

    NASA Astrophysics Data System (ADS)

    Sakatani, Kenji; Ono, Takahiko; Kobayasi, Yasuhide; Hikita, Shinichi; Saito, Mitsuyuki

    2007-12-01

    In an emergency transportation by ambulance, a patient is transported in a supine position. In this position, a patient's blood pressure (BP) variation depending on an inertial force which occurs when an ambulance accelerates or decelerates. This BP variation causes a critical damage for a patent with brain disorder. In order to keep a patient stable during transportation, it is required to maintain small BP variation. To analyze the BP variation during transportation, a model of the BP variation has so far been made. But, it can estimate the BP variation only in braking. The purpose of this paper is to make a dynamical model of the BP variation which can simulate it in both braking and accelerating. First, to obtain the data to construct the model, we used a tilting bed to measure a head-to-foot acceleration and BP of fingertip. Based on this data, we build a mathematical model whose input is the head-to-foot acceleration and output is the Mean BP variation. It is a switched model which switches two models depending on the jerk. We add baroreceptor reflex to the model as a offset value.

  12. Enhanced solar radiation pressure modeling for Galileo satellites

    NASA Astrophysics Data System (ADS)

    Montenbruck, O.; Steigenberger, P.; Hugentobler, U.

    2015-03-01

    This paper introduces a new approach for modeling solar radiation pressure (SRP) effects on Global Navigation Satellite Systems (GNSSs). It focuses on the Galileo In-Orbit Validation (IOV) satellites, for which obvious SRP modeling deficits can be identified in presently available precise orbit products. To overcome these problems, the estimation of empirical accelerations in the Sun direction (D), solar panel axis (Y) and the orthogonal (B) axis is complemented by an a priori model accounting for the contribution of the rectangular spacecraft body. Other than the GPS satellites, which comprise an almost cubic body, the Galileo IOV satellites exhibit a notably rectangular shape with a ratio of about 2:1 for the main body axes. Use of the a priori box model allows to properly model the varying cross section exposed to the Sun during yaw-steering attitude mode and helps to remove systematic once-per-revolution orbit errors that have so far affected the Galileo orbit determination. Parameters of a simple a priori cuboid model suitable for the IOV satellites are established from the analysis of a long-term set of GNSS observations collected with the global network of the Multi-GNSS Experiment of the International GNSS Service. The model is finally demonstrated to reduce the peak magnitude of radial orbit errors from presently 20 cm down to 5 cm outside eclipse phases.

  13. Automating risk analysis of software design models.

    PubMed

    Frydman, Maxime; Ruiz, Guifré; Heymann, Elisa; César, Eduardo; Miller, Barton P

    2014-01-01

    The growth of the internet and networked systems has exposed software to an increased amount of security threats. One of the responses from software developers to these threats is the introduction of security activities in the software development lifecycle. This paper describes an approach to reduce the need for costly human expertise to perform risk analysis in software, which is common in secure development methodologies, by automating threat modeling. Reducing the dependency on security experts aims at reducing the cost of secure development by allowing non-security-aware developers to apply secure development with little to no additional cost, making secure development more accessible. To automate threat modeling two data structures are introduced, identification trees and mitigation trees, to identify threats in software designs and advise mitigation techniques, while taking into account specification requirements and cost concerns. These are the components of our model for automated threat modeling, AutSEC. We validated AutSEC by implementing it in a tool based on data flow diagrams, from the Microsoft security development methodology, and applying it to VOMS, a grid middleware component, to evaluate our model's performance.

  14. The globalization of risk and risk perception: why we need a new model of risk communication for vaccines.

    PubMed

    Larson, Heidi; Brocard Paterson, Pauline; Erondu, Ngozi

    2012-11-01

    Risk communication and vaccines is complex and the nature of risk perception is changing, with perceptions converging, evolving and having impacts well beyond specific geographic localities and points in time, especially when amplified through the Internet and other modes of global communication. This article examines the globalization of risk perceptions and their impacts, including the example of measles and the globalization of measles, mumps and rubella (MMR) vaccine risk perceptions, and calls for a new, more holistic model of risk assessment, risk communication and risk mitigation, embedded in an ongoing process of risk management for vaccines and immunization programmes. It envisions risk communication as an ongoing process that includes trust-building strategies hand-in-hand with operational and policy strategies needed to mitigate and manage vaccine-related risks, as well as perceptions of risk.

  15. Personalized Predictive Modeling and Risk Factor Identification using Patient Similarity.

    PubMed

    Ng, Kenney; Sun, Jimeng; Hu, Jianying; Wang, Fei

    2015-01-01

    Personalized predictive models are customized for an individual patient and trained using information from similar patients. Compared to global models trained on all patients, they have the potential to produce more accurate risk scores and capture more relevant risk factors for individual patients. This paper presents an approach for building personalized predictive models and generating personalized risk factor profiles. A locally supervised metric learning (LSML) similarity measure is trained for diabetes onset and used to find clinically similar patients. Personalized risk profiles are created by analyzing the parameters of the trained personalized logistic regression models. A 15,000 patient data set, derived from electronic health records, is used to evaluate the approach. The predictive results show that the personalized models can outperform the global model. Cluster analysis of the risk profiles show groups of patients with similar risk factors, differences in the top risk factors for different groups of patients and differences between the individual and global risk factors.

  16. Fluid-structure Interaction Modeling of Aneurysmal Conditions with High and Normal Blood Pressures

    NASA Astrophysics Data System (ADS)

    Torii, Ryo; Oshima, Marie; Kobayashi, Toshio; Takagi, Kiyoshi; Tezduyar, Tayfun E.

    2006-09-01

    Hemodynamic factors like the wall shear stress play an important role in cardiovascular diseases. To investigate the influence of hemodynamic factors in blood vessels, the authors have developed a numerical fluid-structure interaction (FSI) analysis technique. The objective is to use numerical simulation as an effective tool to predict phenomena in a living human body. We applied the technique to a patient-specific arterial model, and with that we showed the effect of wall deformation on the WSS distribution. In this paper, we compute the interaction between the blood flow and the arterial wall for a patient-specific cerebral aneurysm with various hemodynamic conditions, such as hypertension. We particularly focus on the effects of hypertensive blood pressure on the interaction and the WSS, because hypertension is reported to be a risk factor in rupture of aneurysms. We also aim to show the possibility of FSI computations with hemodynamic conditions representing those risk factors in cardiovascular disease. The simulations show that the transient behavior of the interaction under hypertensive blood pressure is significantly different from the interaction under normal blood pressure. The transient behavior of the blood-flow velocity, and the resulting WSS and the mechanical stress in the aneurysmal wall, are significantly affected by hypertension. The results imply that hypertension affects the growth of an aneurysm and the damage in arterial tissues.

  17. NASA's Current Evidence and Hypothesis for the Visual Impairment and Intracranial Pressure Risk

    NASA Technical Reports Server (NTRS)

    Otto, Christian A.; Norsk, Peter; Oubre, Cherie M.; Pass, Anastas F.; Tarver, William

    2012-01-01

    While 40 years of human spaceflight exploration has reported visual decrement to a certain extent in a subgroup of astronauts, recent data suggests that there is indeed a subset of crewmembers that experience refraction changes (hyperoptic shift), cotton wool spot formation, choroidal fold development, papilledema, optic nerve sheath distention and/or posterior globe flattening with varying degrees of severity and permanence. Pre and postflight ocular measures have identified a potential risk of permanent visual changes as a result of microgravity exposure, which has been defined as the Visual Impairment and Intracranial Pressure risk (VIIP). The combination of symptoms are referred to as the VIIP syndrome. It is thought that the ocular structural and optic nerve changes are caused by events precipitated by the cephalad fluid shift crewmembers experience during long-duration spaceflight. Three important systems, ocular, cardiovascular, and central nervous, seem to be involved in the development of symptoms, but the etiology is still under speculation. It is believed that some crewmembers are more susceptible to these changes due to genetic/anatomical predisposition or lifestyle (fitness) related factors. Future research will focus on determining the etiology of the VIIP syndrome and development of mechanisms to mitigate the spaceflight risk.

  18. Generic risk insights for Westinghouse and Combustion Engineering pressurized water reactors

    SciTech Connect

    Travis, R.; Taylor, J.; Fresco, A. ); Chung, J. )

    1990-11-01

    A methodology has been developed to extract generic risk-based information from probabilistic risk assessments (PRAs) of Westinghouse and Combustion Engineering (CE) pressurized water reactors (PWRs) and apply the insights gained to Westinghouse and Ce plants have not been subjected to a PRA. The available PRAs (five Westinghouse plants and one CE plant) were examined to identify the most probable, i.e., dominant accident sequences at each plant. The goal was to include all sequences which represented at least 80% of core damage frequency. If the same plant specific dominant accident sequence appeared within this boundary in at least two plant PRAs, the sequence was considered to be a representative sequence. Eleven sequences met this definition. From these sequences, the most important component failures and human errors that contributed to each sequence have been prioritized. Guidance is provided to prioritize the representative sequences and modify selected basic events that have been shown to be sensitive to the plant specific design or operating variations of the contributing PRAs. This risk-based guidance can be used for utility and NRC activities including operator training maintenance, design review, and inspections.

  19. Assessing patients' risk of febrile neutropenia: is there a correlation between physician-assessed risk and model-predicted risk?

    PubMed

    Lyman, Gary H; Dale, David C; Legg, Jason C; Abella, Esteban; Morrow, Phuong Khanh; Whittaker, Sadie; Crawford, Jeffrey

    2015-08-01

    This study evaluated the correlation between the risk of febrile neutropenia (FN) estimated by physicians and the risk of severe neutropenia or FN predicted by a validated multivariate model in patients with nonmyeloid malignancies receiving chemotherapy. Before patient enrollment, physician and site characteristics were recorded, and physicians self-reported the FN risk at which they would typically consider granulocyte colony-stimulating factor (G-CSF) primary prophylaxis (FN risk intervention threshold). For each patient, physicians electronically recorded their estimated FN risk, orders for G-CSF primary prophylaxis (yes/no), and patient characteristics for model predictions. Correlations between physician-assessed FN risk and model-predicted risk (primary endpoints) and between physician-assessed FN risk and G-CSF orders were calculated. Overall, 124 community-based oncologists registered; 944 patients initiating chemotherapy with intermediate FN risk enrolled. Median physician-assessed FN risk over all chemotherapy cycles was 20.0%, and median model-predicted risk was 17.9%; the correlation was 0.249 (95% CI, 0.179-0.316). The correlation between physician-assessed FN risk and subsequent orders for G-CSF primary prophylaxis (n = 634) was 0.313 (95% CI, 0.135-0.472). Among patients with a physician-assessed FN risk ≥ 20%, 14% did not receive G-CSF orders. G-CSF was not ordered for 16% of patients at or above their physician's self-reported FN risk intervention threshold (median, 20.0%) and was ordered for 21% below the threshold. Physician-assessed FN risk and model-predicted risk correlated weakly; however, there was moderate correlation between physician-assessed FN risk and orders for G-CSF primary prophylaxis. Further research and education on FN risk factors and appropriate G-CSF use are needed.

  20. Reduced Uterine Perfusion Pressure (RUPP) Model of Preeclampsia in Mice

    PubMed Central

    Fushima, Tomofumi; Sekimoto, Akiyo; Minato, Takahiro; Ito, Takuya; Oe, Yuji; Kisu, Kiyomi; Sato, Emiko; Funamoto, Kenichi; Hayase, Toshiyuki; Kimura, Yoshitaka; Ito, Sadayoshi; Sato, Hiroshi; Takahashi, Nobuyuki

    2016-01-01

    Preeclampsia (PE) is a pregnancy-induced hypertension with proteinuria that typically develops after 20 weeks of gestation. A reduction in uterine blood flow causes placental ischemia and placental release of anti-angiogenic factors such as sFlt-1 followed by PE. Although the reduced uterine perfusion pressure (RUPP) model is widely used in rats, investigating the role of genes on PE using genetically engineered animals has been problematic because it has been difficult to make a useful RUPP model in mice. To establish a RUPP model of PE in mice, we bilaterally ligated ovarian vessels distal to ovarian branches, uterine vessels, or both in ICR-strain mice at 14.5 days post coitum (dpc). Consequently, these mice had elevated BP, increased urinary albumin excretion, severe endotheliosis, and mesangial expansion. They also had an increased incidence of miscarriage and premature delivery. Embryonic weight at 18.5 dpc was significantly lower than that in sham mice. The closer to the ligation site the embryos were, the higher the resorption rate and the lower the embryonic weight. The phenotype was more severe in the order of ligation at the ovarian vessels < uterine vessels < both. Unlike the RUPP models described in the literature, this model did not constrict the abdominal aorta, which allowed BP to be measured with a tail cuff. This novel RUPP model in mice should be useful for investigating the pathogenesis of PE in genetically engineered mice and for evaluating new therapies for PE. PMID:27187738

  1. Urban Drainage Modeling and Flood Risk Management

    NASA Astrophysics Data System (ADS)

    Schmitt, Theo G.; Thomas, Martin

    The European research project in the EUREKA framework, RisUrSim (Σ!2255) has been worked out by a project consortium including industrial mathematics and water engineering research institutes, municipal drainage works as well as an insurance company. The overall objective has been the development of a simulation to allow flood risk analysis and cost-effective management for urban drainage systems. In view of the regulatory background of European Standard EN 752, the phenomenon of urban flooding caused by surcharged sewer systems in urban drainage systems is analyzed, leading to the necessity of dual drainage modeling. A detailed dual drainage simulation model is described based upon hydraulic flow routing procedures for surface flow and pipe flow. Special consideration is given to the interaction between surface and sewer flow in order to most accurately compute water levels above ground as a basis for further assessment of possible damage costs. The model application is presented for small case study in terms of data needs, model verification, and first simulation results.

  2. Mathematical modelling to support traceable dynamic calibration of pressure sensors

    NASA Astrophysics Data System (ADS)

    Matthews, C.; Pennecchi, F.; Eichstädt, S.; Malengo, A.; Esward, T.; Smith, I.; Elster, C.; Knott, A.; Arrhén, F.; Lakka, A.

    2014-06-01

    This paper focuses on the mathematical modelling required to support the development of new primary standard systems for traceable calibration of dynamic pressure sensors. We address two fundamentally different approaches to realizing primary standards, specifically the shock tube method and the drop-weight method. Focusing on the shock tube method, the paper presents first results of system identification and discusses future experimental work that is required to improve the mathematical and statistical models. We use simulations to identify differences between the shock tube and drop-weight methods, to investigate sources of uncertainty in the system identification process and to assist experimentalists in designing the required measuring systems. We demonstrate the identification method on experimental results and draw conclusions.

  3. Nondissipative Velocity and Pressure Regularizations for the ICON Model

    NASA Astrophysics Data System (ADS)

    Restelli, M.; Giorgetta, M.; Hundertmark, T.; Korn, P.; Reich, S.

    2009-04-01

    A challenging aspect in the numerical simulation of atmospheric and oceanic flows is the multiscale character of the problem both in space and time. The small spacial scales are generated by the turbulent energy and enstrophy cascades, and are usually dealt with by means of turbulence parametrizations, while the small temporal scales are governed by the propagation of acoustic and gravity waves, which are of little importance for the large scale dynamics and are often eliminated by means of a semi-implicit time discretization. We propose to treat both phenomena of subgrid turbulence and temporal scale separation in a unified way by means of nondissipative regularizations of the underlying model equations. More precisely, we discuss the use of two regularized equation sets: the velocity regularization, also know as Lagrangian averaged Navier-Stokes system, and the pressure regularization. Both regularizations are nondissipative since they do not enhance the dissipation of energy and enstrophy of the flow. The velocity regularization models the effects of the subgrid velocity fluctuations on the mean flow, it has thus been proposed as a turbulence parametrization and it has been found to yield promising results in ocean modeling [HHPW08]. In particular, the velocity regularization results in a higher variability of the numerical solution. The pressure regularization, discussed in [RWS07], modifies the propagation of acoustic and gravity waves so that the resulting system can be discretized explicitly in time with time steps analogous to those allowed by a semi-implicit method. Compared to semi-implicit time integrators, however, the pressure regularization takes fully into account the geostrophic balance of the flow. We discuss here the implementation of the velocity and pressure regularizations within the numerical framework of the ICON general circulation model (GCM) [BR05] for the case of the rotating shallow water system, showing how the original numerical

  4. Whole-body mathematical model for simulating intracranial pressure dynamics

    NASA Technical Reports Server (NTRS)

    Lakin, William D. (Inventor); Penar, Paul L. (Inventor); Stevens, Scott A. (Inventor); Tranmer, Bruce I. (Inventor)

    2007-01-01

    A whole-body mathematical model (10) for simulating intracranial pressure dynamics. In one embodiment, model (10) includes 17 interacting compartments, of which nine lie entirely outside of intracranial vault (14). Compartments (F) and (T) are defined to distinguish ventricular from extraventricular CSF. The vasculature of the intracranial system within cranial vault (14) is also subdivided into five compartments (A, C, P, V, and S, respectively) representing the intracranial arteries, capillaries, choroid plexus, veins, and venous sinus. The body's extracranial systemic vasculature is divided into six compartments (I, J, O, Z, D, and X, respectively) representing the arteries, capillaries, and veins of the central body and the lower body. Compartments (G) and (B) include tissue and the associated interstitial fluid in the intracranial and lower regions. Compartment (Y) is a composite involving the tissues, organs, and pulmonary circulation of the central body and compartment (M) represents the external environment.

  5. Measures of Residual Risk with Connections to Regression, Risk Tracking, Surrogate Models, and Ambiguity

    DTIC Science & Technology

    2015-05-20

    Measures of Residual Risk with Connections to Regression, Risk Tracking, Surrogate Models, and Ambiguity1 R. Tyrrell Rockafellar Johannes O. Royset... Measures of residual risk are developed as extension of measures of risk. They view a random variable of interest in concert with an auxiliary random...forecasting and generalized regression. We establish the fundamental properties in this framework and show that measures of residual risk along with

  6. RSRM Chamber Pressure Oscillations: Transit Time Models and Unsteady CFD

    NASA Technical Reports Server (NTRS)

    Nesman, Tom; Stewart, Eric

    1996-01-01

    Space Shuttle solid rocket motor low frequency internal pressure oscillations have been observed since early testing. The same type of oscillations also are present in the redesigned solid rocket motor (RSRM). The oscillations, which occur during RSRM burn, are predominantly at the first three motor cavity longitudinal acoustic mode frequencies. Broadband flow and combustion noise provide the energy to excite these modes at low levels throughout motor burn, however, at certain times during burn the fluctuating pressure amplitude increases significantly. The increased fluctuations at these times suggests an additional excitation mechanism. The RSRM has inhibitors on the propellant forward facing surface of each motor segment. The inhibitors are in a slot at the segment field joints to prevent burning at that surface. The aft facing segment surface at a field joint slot burns and forms a cavity of time varying size. Initially the inhibitor is recessed in the field joint cavity. As propellant burns away the inhibitor begins to protrude into the bore flow. Two mechanisms (transit time models) that are considered potential pressure oscillation excitations are cavity-edge tones, and inhibitor hole-tones. Estimates of frequency variation with time of longitudinal acoustic modes, cavity edge-tones, and hole-tones compare favorably with frequencies measured during motor hot firing. It is believed that the highest oscillation amplitudes occur when vortex shedding frequencies coincide with motor longitudinal acoustic modes. A time accurate computational fluid dynamic (CFD) analysis was made to replicate the observations from motor firings and to observe the transit time mechanisms in detail. FDNS is the flow solver used to detail the time varying aspects of the flow. The fluid is approximated as a single-phase ideal gas. The CFD model was an axisymmetric representation of the RSRM at 80 seconds into burn.Deformation of the inhibitors by the internal flow was determined

  7. High blood pressure and associated risk factors as indicator of preclinical hypertension in rural West Africa

    PubMed Central

    Jobe, Modou; Agbla, Schadrac C.; Prentice, Andrew M.; Hennig, Branwen J.

    2017-01-01

    Abstract Hypertension is fast becoming a major public health problem across sub-Saharan Africa. We sought to determine the prevalence of high blood pressure (BP) and associated risk factors as indicator of preclinical hypertension in a rural Gambian population. We analyzed data on 6160 healthy Gambians cross-sectionally. Attention was given to 5 to <18-year olds (N = 3637), as data from sub-Saharan Africa on this young age group are scarce. High BP was defined as systolic blood pressure (SBP) above the 95th percentile for age-sex specific height z scores in <18-year olds employing population-specific reference values. Standard high BP categories were applied to ≥18-year olds. In <18-year olds, the multivariable analysis gave an adjusted high BP prevalence ratio of 0.95 (95% confidence interval [CI] 0.92–0.98; P = 0.002) for age and 1.13 (95% CI 1.06–1.19; P < 0.0001) for weight-for-height z score (zWT-HT); sex and hemoglobin were not shown to affect high BP. In adults age 1.05 (95% CI 1.04–1.05; P < 0.0001), body mass index z score 1.28 (95% CI 1.16–1.40; P < 0.0001), hemoglobin 0.90 (95% CI 0.85–0.96; P < 0.0001) and high fasting glucose 2.60 (95% CI 2.02–3.36; P < 0.0001, though the number was very low) were confirmed as risk factors for high BP prevalence; sex was not associated. The reported high BP prevalence and associated risk factors in adults are comparable to other studies conducted in the region. The observed high BP prevalence of 8.2% (95% CI 7.4–9.2) in our generally lean young Gambians (<18 years) is alarming, given that high BP tracks from childhood to adulthood. Hence there is an urgent need for further investigation into risk factors of pediatric high BP/hypertension even in rural African settings. PMID:28353557

  8. Antihypertensive combination therapy: optimizing blood pressure control and cardiovascular risk reduction.

    PubMed

    Nesbitt, Shawna D

    2007-11-01

    Treating hypertension reduces the rates of myocardial infarction, stroke, and renal disease; however, clinical trial experience suggests that monotherapy is not likely to be successful for achieving goal blood pressure (BP) levels in many hypertensive patients. In multiple recent clinical trials including various subsets of hypertensive patients, the achievement of BP goal has typically required the combination of 2 or more medications, particularly in patients with BP levels>160/100 mm Hg. When initiating combination therapy for hypertension, careful consideration must be given to the choice of medication. Clinical trial evidence has shown the efficacy of various combinations of angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers, calcium channel blockers, and diuretics in reducing BP and cardiovascular risk. Ongoing trials should provide additional guidance on the optimal choice of combination regimens in specific clinical settings.

  9. Evaluation of the pressure ulcers risk scales with critically ill patients: a prospective cohort study 1

    PubMed Central

    Borghardt, Andressa Tomazini; do Prado, Thiago Nascimento; de Araújo, Thiago Moura; Rogenski, Noemi Marisa Brunet; Bringuente, Maria Edla de Oliveira

    2015-01-01

    AIMS: to evaluate the accuracy of the Braden and Waterlow risk assessment scales in critically ill inpatients. METHOD: this prospective cohort study, with 55 patients in intensive care units, was performed through evaluation of sociodemographic and clinical variables, through the application of the scales (Braden and Waterlow) upon admission and every 48 hours; and through the evaluation and classification of the ulcers into categories. RESULTS: the pressure ulcer incidence was 30.9%, with the Braden and Waterlow scales presenting high sensitivity (41% and 71%) and low specificity (21% and 47%) respectively in the three evaluations. The cut off scores found in the first, second and third evaluations were 12, 12 and 11 in the Braden scale, and 16, 15 and 14 in the Waterlow scale. CONCLUSION: the Braden scale was shown to be a good screening instrument, and the Waterlow scale proved to have better predictive power. PMID:25806628

  10. Potentially modifiable risk factors among veterans with spinal cord injury hospitalized for severe pressure ulcers: a descriptive study

    PubMed Central

    Guihan, Marylou; Bombardier, Charles H.

    2012-01-01

    Context/objective Pressure ulcers (PrUs) are a serious, costly and potentially life-long complication of spinal cord injury (SCI). Co-morbid conditions increase PrU risk, adding to the health behavior challenges faced by people with SCI. Little is known about medical co-morbidities, health beliefs, risk, protective behaviors, and readiness to improve skin care behaviors in people with SCI. This study describes the potentially modifiable medical and behavioral risk factors among veterans with SCI and severe (Stage III/IV) PrUs. Design Cross-sectional observational design. Setting 6 VA SCI Centers. Participants Convenience sample from a larger intervention study of 148 veterans hospitalized for PrUs. Interventions Not applicable. Outcome measures Knowledge, PrU risk, skin protective behaviors, health beliefs, and practices, health locus of control, skin worsening. Results Most ulcers were stage IV (73%) and about half had 2+ PrUs. Participants reported a mean of 6.7 co-morbid conditions (respiratory, gastrointestinal, renal disease/urinary tract infection, autonomic dysreflexia, diabetes, bowel/bladder incontinence). Potential intervention opportunities include proactive assistance with management of multiple chronic conditions, substance abuse, nutrition, adherence to skin protective behaviors, readiness to change, and access to resources. Overall knowledge about PrUs was low, especially for how to prevent PrUs and what to do if skin breakdown occurs. Conclusion Future research should address whether comprehensive models that include patient self-management, decision support and health care system, and proactive behavior change assistance for patients help reduce PrU incidence and recurrence in persons with SCI. Trial Registration http://clinicaltrials.gov/ct2/show/NCT00105859 PMID:22925750

  11. Risk assessment compatible fire models (RACFMs)

    SciTech Connect

    Lopez, A.R.; Gritzo, L.A.; Sherman, M.P.

    1998-07-01

    A suite of Probabilistic Risk Assessment Compatible Fire Models (RACFMs) has been developed to represent the hazard posed by a pool fire to weapon systems transported on the B52-H aircraft. These models represent both stand-off (i.e., the weapon system is outside of the flame zone but exposed to the radiant heat load from fire) and fully-engulfing scenarios (i.e., the object is fully covered by flames). The approach taken in developing the RACFMs for both scenarios was to consolidate, reconcile, and apply data and knowledge from all available resources including: data and correlations from the literature, data from an extensive full-scale fire test program at the Naval Air Warfare Center (NAWC) at China Lake, and results from a fire field model (VULCAN). In the past, a single, effective temperature, T{sub f}, was used to represent the fire. The heat flux to an object exposed to a fire was estimated using the relationship for black body radiation, {sigma}T{sub f}{sup 4}. Significant improvements have been made by employing the present approach which accounts for the presence of temperature distributions in fully-engulfing fires, and uses best available correlations to estimate heat fluxes in stand-off scenarios.

  12. Velocity and pressure characteristics of a model SSME high pressure fuel turbopump

    NASA Technical Reports Server (NTRS)

    Tse, D. G-N.; Sabnis, J. S.; Mcdonald, H.

    1991-01-01

    Under the present effort an experiment rig has been constructed, an instrumentation package developed and a series of mean and rms velocity and pressure measurements made in a turbopump which modelled the first stage of the Space Shuttle Main Engine (SSME) High Pressure Fuel Turbopump. The rig was designed so as to allow initial experiments with a single configuration consisting of a bell-mouth inlet, a flight impeller, a vaneless diffuser and a volute. Allowance was made for components such as inlet guide vanes, exit guide vanes, downstream pumps, etc. to be added in future experiments. This flexibility will provide a clear baseline set of experiments and allow evaluation in later experiments of the effect of adding specific components upon the pump performance properties. The rotational speed of the impeller was varied between 4260 and 7680 rpm which covered the range of scaled SSME rotation speeds when due allowance is made for the differing stagnation temperature, model to full scale. The results at the inlet obtained with rotational speeds of 4260, 6084 and 7680 rpm showed that the axial velocity at the bell-mouth inlet remained roughly constant at 2.2 of the bulk velocity at the exit of the turbopump near the center of the inlet, but it decreased rapidly with increasing radius at all three speeds. Reverse flow occurred at a radius greater than 0.9 R for all three speeds and the maximum negative velocity reduced from 1.3 of the bulk velocity at the exit of the turbopump at 4260 rpm to 0.35 at 7680 rpm, suggesting that operating at a speed closer to the design condition of 8700 rpm improved the inlet characteristics. The reverse flow caused positive prerotation at the impeller inlet which was negligibly small near the center but reached 0.7 of the impeller speed at the outer annulus. The results in the diffuser and the volute obtained at 7680 rpm show that the hub and shroud walls of the diffuser were characterized by regions of transient reverse flow with

  13. Endothelial function, blood pressure control, and risk modification: impact of irbesartan alone or in combination

    PubMed Central

    Derosa, Giuseppe; Salvadeo, Sibilla AT

    2010-01-01

    Irbesartan, an angiotensin II type 1 receptor antagonist, is approved as monotherapy, or in combination with other drugs, for the treatment of hypertension in many countries worldwide. Data in the literature suggest that irbesartan is effective for reducing blood pressure over a 24-hour period with once-daily administration, and slows the progression of renal disease in patients with hypertension and type 2 diabetes. Furthermore, irbesartan shows a good safety and tolerability profile, compared with angiotensin II inhibitors and other angiotensin II type 1 receptor antagonists. Thus, irbesartan appears to be a useful treatment option for patients with hypertension, including those with type 2 diabetes and nephropathy. Irbesartan has an inhibitory effect on the pressor response to angiotensin II and improves arterial stiffness, vascular endothelial dysfunction, and inflammation in hypertensive patients. There has been considerable interest recently in the renoprotective effect of irbesartan, which appears to be independent of reductions in blood pressure. In particular, mounting data suggests that irbesartan improves endothelial function, oxidative stress, and inflammation in the kidneys. Recent studies have highlighted a possible role for irbesartan in improving coronary artery inflammation and vascular dysfunction. In this review we summarize and comment on the most important data available with regard to antihypertensive effect, endothelial function improvement, and cardiovascular risk reduction with irbesartan. PMID:21949618

  14. Risk Assessment for Titanium Pressure Vessels Operating Inside the ARES I's Liquid Hydrogen Tank Environment

    NASA Technical Reports Server (NTRS)

    Lee, Jonathan A.

    2008-01-01

    Titanium alloy (Ti-6-4) is currently being proposed for the manufacturing of pressure vessels (PV) for storage of compressed helium gas, which are mounted inside the ARES I's liquid hydrogen (LH2) tank. At cryogenic temperature, titanium alloys usually have the highest strength-to-weight ratio property and have been considered as the metallic materials of choice for lightweight PV operating in LH2 environment. Titanium PV s are also considered as heritage hardware because they have been used by NASA for the Saturn IV-B rocket s LH2 tank in the mid 1960 s. However, hydrogen embrittlement is possible if Ti-6-4 alloy is exposed to gaseous hydrogen at certain pressure and temperature during the LH2 tank filling and draining operations on the launch pad, and during the J2X engine burn period for the ARES I s upper stage. Additionally, the fracture toughness and ductility properties of Ti-6-4 are significantly decreased at cryogenic temperature. These factors do not necessary preclude the use of titanium PV in hydrogen or at cryogenic applications; however, their synergistic effects and the material damage tolerance must be accounted for in the mission life assessment for PV s, which are considered as fracture critical hardware. In this paper, an overview of the risk assessment for Ti-6-4 alloy, strategy to control hydrogen embrittlement and brief metallic material trade study for PV operating in LH2 tank will be presented.

  15. Fluctuation in systolic blood pressure is a major systemic risk factor for development of primary open-angle glaucoma

    PubMed Central

    Lee, Na Young; Jung, Younhea; Han, Kyungdo; Park, Chan Kee

    2017-01-01

    We evaluated the risk of development of primary open-angle glaucoma (POAG) in terms of variability in BP using a nationwide, population-based, 11-year longitudinal study using the Korean National Health Insurance Research Database. We included patients who underwent health care examinations more than twice between January 2002 and December 2006. We divided all subjects by the quartiles of variability in systolic blood pressure (SBP), diastolic blood pressure (DBP), and the difference between SBP and DBP. Of the total of 80,021 included subjects, 910 were diagnosed with POAG between January 2007 and December 2013. Both the Kaplan-Meier survival curves and log-rank test data indicated that patients with higher-level BP variability developed POAG significantly more frequently than did patients with lower-level variability (P < 0.001). On multivariate Cox’s regression modeling including gender, age, sex, household income, smoking status, level of alcohol intake, extent of exercise, diabetes mellitus status, dyslipidemia status, SBP, and DBP; the hazard ratios among the highest and lowest quartiles of SD SBP and CV SBP were 1.256 and 1.238, respectively. Our findings suggest that subjects in the highest quartile of SBP variability were significantly more likely to develop POAG in our population-based sample of Korean adults. PMID:28262703

  16. Breast Cancer Risk Assessment SAS Macro (Gail Model)

    Cancer.gov

    A SAS macro (commonly referred to as the Gail Model) that projects absolute risk of invasive breast cancer according to NCI’s Breast Cancer Risk Assessment Tool (BCRAT) algorithm for specified race/ethnic groups and age intervals.

  17. Development, modeling, simulation, and testing of a novel propane-fueled Brayton-Gluhareff cycle acoustically-pressurized ramjet engine

    NASA Astrophysics Data System (ADS)

    Bramlette, Richard B.

    In the 1950s, Eugene Gluhareff built the first working "pressure jet" engine, a variation on the classical ramjet engine with a pressurized inlet system relying on sonic tuning which allowed operation at subsonic speeds. The engine was an unqualified success. Unfortunately, after decades of sales and research, Gluhareff passed away leaving behind no significant published studies of the engine or detailed analysis of its operation. The design was at serious risk of being lost to history. This dissertation is intended to address that risk by studying a novel subscale modification of Gluhareff's original design operating on the same principles. Included is a background of related engine and how the pressure jet is distinct. The preliminary sizing of a pressure jet using closed-form expressions is then discussed followed by a review of propane oxidation modeling, how it integrates into the Computational Fluid Dynamics (CFD) solver, and the modeling of the pressure jet engine cycle with CFD. The simulation was matched to experimental data recorded on a purpose-built test stand recording chamber pressure, exhaust speed (via a Pitot/static system), temperatures, and thrust force. The engine CFD simulation produced a wide range of qualitative results that matched the experimental data well and suggested strong recirculation flows through the engine confirming suspicions about how the engine operates. Engine operating frequency between CFD and experiment also showed good agreement and appeared to be driven by the "Kadenacy Effect." The research effort lastly opens the door for further study of the engine cycle, the use of pressurized intakes to produce static thrust in a ramjet engine, the Gluhareff pressure jet's original geometry, and a wide array of potential applications. A roadmap of further study and applications is detailed including a modeling and testing of larger engines.

  18. Evaluation of fracture models through pressurized-thermal-shock testing

    SciTech Connect

    Pugh, C.E.; Bryan, R.H.; Bass, B.R.; Nanstad, R.K.

    1988-01-01

    Two multiple-transient pressurized-thermal-shock experiments (PTSEs) have been conducted under the NRC-sponsored Heavy-Section Steel Technology (HSST) program. The first test (PTSE-1) employed an SA-508 class 2 steel with high Charpy upper-shelf energy level and a relatively high brittle-to-ductile transition temperature. The second test (PTSE-2) used a 2 1/4 Cr-1 Mo steel (SA-387 grade 22) that had been given a special heat treatment to yield a low Charpy upper-shelf energy level and attendant low tearing resistance. Each experiment included two combined thermal and pressure transients that give rise to propagation and arrest of an initial long flaw that extended about 10% through the thick wall of the test cylinder. Both materials exhibited the ability to inhibit crack propagation by warm prestressing, high initiation toughness values and high crack-arrest toughness values. Cleavage initiation and arrest are modeled well by available fracture theories. However, calculations of ductile tearing based on resistance curves did not consistently predict the observed tearing.

  19. Salt, blood pressure and cardiovascular risk: what is the most adequate preventive strategy? A Swiss perspective

    PubMed Central

    Burnier, Michel; Wuerzner, Gregoire; Bochud, Murielle

    2015-01-01

    Among the various strategies to reduce the incidence of non-communicable diseases reduction of sodium intake in the general population has been recognized as one of the most cost-effective means because of its potential impact on the development of hypertension and cardiovascular diseases. Yet, this strategic health recommendation of the WHO and many other international organizations is far from being universally accepted. Indeed, there are still several unresolved scientific and epidemiological questions that maintain an ongoing debate. Thus what is the adequate low level of sodium intake to recommend to the general population and whether national strategies should be oriented to the overall population or only to higher risk fractions of the population such as salt-sensitive patients are still discussed. In this paper, we shall review the recent results of the literature regarding salt, blood pressure and cardiovascular risk and we present the recommendations recently proposed by a group of experts of Switzerland. The propositions of the participating medical societies are to encourage national health authorities to continue their discussion with the food industry in order to reduce the sodium intake of food products with a target of mean salt intake of 5–6 grams per day in the population. Moreover, all initiatives to increase the information on the effect of salt on health and on the salt content of food are supported. PMID:26321959

  20. Sex, the brain and hypertension: brain oestrogen receptors and high blood pressure risk factors.

    PubMed

    Hay, Meredith

    2016-01-01

    Hypertension is a major contributor to worldwide morbidity and mortality rates related to cardiovascular disease. There are important sex differences in the onset and rate of hypertension in humans. Compared with age-matched men, premenopausal women are less likely to develop hypertension. However, after age 60, the incidence of hypertension increases in women and even surpasses that seen in older men. It is thought that changes in levels of circulating ovarian hormones as women age may be involved in the increase in hypertension in older women. One of the key mechanisms involved in the development of hypertension in both men and women is an increase in sympathetic nerve activity (SNA). Brain regions important for the regulation of SNA, such as the subfornical organ, the paraventricular nucleus and the rostral ventral lateral medulla, also express specific subtypes of oestrogen receptors. Each of these brain regions has also been implicated in mechanisms underlying risk factors for hypertension such as obesity, stress and inflammation. The present review brings together evidence that links actions of oestrogen at these receptors to modulate some of the common brain mechanisms involved in the ability of hypertensive risk factors to increase SNA and blood pressure. Understanding the mechanisms by which oestrogen acts at key sites in the brain for the regulation of SNA is important for the development of novel, sex-specific therapies for treating hypertension.

  1. Genetic Variants in Novel Pathways Influence Blood Pressure and Cardiovascular Disease Risk

    PubMed Central

    2011-01-01

    Blood pressure (BP) is a heritable trait1 influenced by multiple biological pathways and is responsive to environmental stimuli. Over one billion people worldwide have hypertension (BP ≥140 mm Hg systolic [SBP] or ≥90 mm Hg diastolic [DBP])2. Even small increments in BP are associated with increased risk of cardiovascular events3. This genome-wide association study of SBP and DBP, which used a multi-stage design in 200,000 individuals of European descent, identified 16 novel loci: six of these loci contain genes previously known or suspected to regulate BP (GUCY1A3-GUCY1B3; NPR3-C5orf23; ADM; FURIN-FES; GOSR2; GNAS-EDN3); the other 10 provide new clues to BP physiology. A genetic risk score based on 29 genome-wide significant variants was associated with hypertension, left ventricular wall thickness, stroke, and coronary artery disease, but not kidney disease or kidney function. We also observed associations with BP in East Asian, South Asian, and African ancestry individuals. Our findings provide new insights into the genetics and biology of BP, and suggest novel potential therapeutic pathways for cardiovascular disease prevention. PMID:21909115

  2. Use of a risk assessment method to improve the safety of negative pressure wound therapy.

    PubMed

    Lelong, Anne-Sophie; Martelli, Nicolas; Bonan, Brigitte; Prognon, Patrice; Pineau, Judith

    2014-06-01

    To conduct a risk analysis of the negative pressure wound therapy (NPWT) care process and to improve the safety of NPWT, a working group of nurses, hospital pharmacists, physicians and hospital managers performed a risk analysis for the process of NPWT care. The failure modes, effects and criticality analysis (FMECA) method was used for this analysis. Failure modes and their consequences were defined and classified as a function of their criticality to identify priority actions for improvement. By contrast to classical FMECA, the criticality index (CI) of each consequence was calculated by multiplying occurrence, severity and detection scores. We identified 13 failure modes, leading to 20 different consequences. The CI of consequences was initially 712, falling to 357 after corrective measures were implemented. The major improvements proposed included the establishment of 6-monthly training cycles for nurses, physicians and surgeons and the introduction of computerised prescription for NPWT. The FMECA method also made it possible to prioritise actions as a function of the criticality ranking of consequences and was easily understood and used by the working group. This study is, to our knowledge, the first to use the FMECA method to improve the safety of NPWT.

  3. Development and Validation of a Pressurization System Model for a Crossfeed Subscale Water Test Article

    NASA Technical Reports Server (NTRS)

    Nguyen, Han; Mazurkivich, Pete

    2006-01-01

    A pressurization system model was developed for a crossfeed subscale water test article using the EASY5 modeling software. The model consisted of an integrated tank pressurization and pressurization line model. The tank model was developed using the general purpose library, while the line model was assembled from the gas dynamic library. The pressurization system model was correlated to water test data obtained from nine test runs conducted on the crossfeed subscale test article. The model was first correlated to a representative test run and frozen. The correlated model was then used to predict the tank pressures and compared with the test data for eight other runs. The model prediction showed excellent agreement with the test data, allowing it to be used in a later study to analyze the pressurization system performance of a full-scale bimese vehicle with cryogenic propellants.

  4. Pressure swing adsorption processes: Intraparticle diffusion/convection models

    SciTech Connect

    Lu, Zuping; Loureiro, J.M.; LeVan, M.D. . Dept. of Chemical Engineering); Rodrigues, A.E. . School of Engineering)

    1993-11-01

    The dynamic behavior of a three-step one-column isothermal PSA process is assessed by simulation; three models are used: equilibrium, intraparticle diffusion, and intraparticle diffusion/convection. Two process performance parameters, product enrichment and recovery of the light component, are used to measure the separation performance. The effects of several operating variables on the process performance are addressed. Higher pressure ratios (P[sub h]/P[sub l]) and higher adsorption capacities increase the process performance. The process performance is practically independent of the step rates, although it can decrease if high feed rates are used together with large feed duration times. The limiting performance of the system is found in the absence of mass-transfer resistances. Intraparticle convection, enhancing mass transfer inside particles, increases the process performance relative to intraparticle diffusion alone; the improvement is limited by the equilibrium situation.

  5. A Risk Analysis Methodology to Address Human and Organizational Factors in Offshore Drilling Safety: With an Emphasis on Negative Pressure Test

    NASA Astrophysics Data System (ADS)

    Tabibzadeh, Maryam

    misinterpretation. Finally, a rational decision making model is introduced to quantify a section of the developed conceptual framework in the previous step and analyze the impact of different decision making biases on negative pressure test results. Along with the corroborating findings of previous studies, the analysis of the developed conceptual framework in this paper indicates that organizational factors are root causes of accumulated errors and questionable decisions made by personnel or management. Further analysis of this framework identifies procedural issues, economic pressure, and personnel management issues as the organizational factors with the highest influence on misinterpreting a negative pressure test. It is noteworthy that the captured organizational factors in the introduced conceptual framework are not only specific to the scope of the NPT. Most of these organizational factors have been identified as not only the common contributing causes of other offshore drilling accidents but also accidents in other oil and gas related operations as well as high-risk operations in other industries. In addition, the proposed rational decision making model in this research introduces a quantitative structure for analysis of the results of a conducted NPT. This model provides a structure and some parametric derived formulas to determine a cut-off point value, which assists personnel in accepting or rejecting an implemented negative pressure test. Moreover, it enables analysts to assess different decision making biases involved in the process of interpreting a conducted negative pressure test as well as the root organizational factors of those biases. In general, although the proposed integrated research methodology in this dissertation is developed for the risk assessment of human and organizational factors contributions in negative pressure test misinterpretation, it can be generalized and be potentially useful for other well control situations, both offshore and onshore; e

  6. Quadratic function between arterial partial oxygen pressure and mortality risk in sepsis patients: an interaction with simplified acute physiology score

    PubMed Central

    Zhang, Zhongheng; Ji, Xuqing

    2016-01-01

    Oxygen therapy is widely used in emergency and critical care settings, while there is little evidence on its real therapeutic effect. The study aimed to explore the impact of arterial oxygen partial pressure (PaO2) on clinical outcomes in patients with sepsis. A large clinical database was employed for the study. Subjects meeting the diagnostic criteria of sepsis were eligible for the study. All measurements of PaO2 were extracted. The primary endpoint was death from any causes during hospital stay. Survey data analysis was performed by using individual ICU admission as the primary sampling unit. Quadratic function was assumed for PaO2 and its interaction with other covariates were explored. A total of 199,125 PaO2 samples were identified for 11,002 ICU admissions. Each ICU stay comprised 18 PaO2 samples in average. The fitted multivariable model supported our hypothesis that the effect of PaO2 on mortality risk was in quadratic form. There was significant interaction between PaO2 and SAPS-I (p = 0.007). Furthermore, the main effect of PaO2 on SOFA score was nonlinear. The study shows that the effect of PaO2 on mortality risk is in quadratic function form, and there is significant interaction between PaO2 and severity of illness. PMID:27734905

  7. Quadratic function between arterial partial oxygen pressure and mortality risk in sepsis patients: an interaction with simplified acute physiology score.

    PubMed

    Zhang, Zhongheng; Ji, Xuqing

    2016-10-13

    Oxygen therapy is widely used in emergency and critical care settings, while there is little evidence on its real therapeutic effect. The study aimed to explore the impact of arterial oxygen partial pressure (PaO2) on clinical outcomes in patients with sepsis. A large clinical database was employed for the study. Subjects meeting the diagnostic criteria of sepsis were eligible for the study. All measurements of PaO2 were extracted. The primary endpoint was death from any causes during hospital stay. Survey data analysis was performed by using individual ICU admission as the primary sampling unit. Quadratic function was assumed for PaO2 and its interaction with other covariates were explored. A total of 199,125 PaO2 samples were identified for 11,002 ICU admissions. Each ICU stay comprised 18 PaO2 samples in average. The fitted multivariable model supported our hypothesis that the effect of PaO2 on mortality risk was in quadratic form. There was significant interaction between PaO2 and SAPS-I (p = 0.007). Furthermore, the main effect of PaO2 on SOFA score was nonlinear. The study shows that the effect of PaO2 on mortality risk is in quadratic function form, and there is significant interaction between PaO2 and severity of illness.

  8. Ambulatory Blood Pressure Monitoring (ABPM) as the reference standard for diagnosis of hypertension and assessment of vascular risk in adults.

    PubMed

    Hermida, Ramón C; Smolensky, Michael H; Ayala, Diana E; Portaluppi, Francesco

    2015-01-01

    New information has become available since the ISC, AAMCC, and SECAC released their first extensive guidedelines to improve the diagnosis and treatment of adult arterial hypertension. A critical assessment of evidence and a comparison of what international guidelines now propose are the basis for the following statements, which update the recommendations first issued in 2013. Office blood pressure (BP) measurements should no longer be considered to be the "gold standard" for the diagnosis of hypertension and assessment of cardiovascular risk. Relying on office BP, even when supplemented with at-home wake-time self-measurements, to identify high-risk individuals, disregarding circadian BP patterning and asleep BP level, leads to potential misclassification of 50% of all evaluated persons. Accordingly, ambulatory BP monitoring is the recommended reference standard for the diagnosis of true hypertension and accurate assessment of cardiovascular risk in all adults ≥18 yrs of age, regardless of whether office BP is normal or elevated. Asleep systolic BP mean is the most significant independent predictor of cardiovascular events. The sleep-time relative SBP decline adds prognostic value to the statistical model that already includes the asleep systolic BP mean and corrected for relevant confounding variables. Accordingly, the asleep systolic BP mean is the recommended protocol to diagnose hypertension, assess cardiovascular risk, and predict cardiovascular event-free interval. In men, and in the absence of compelling clinical conditions, reference thresholds for diagnosing hypertension are 120/70 mmHg for the asleep systolic/diastolic BP means derived from ambulatory BP monitoring. However, in women, in the absence of complicating co-morbidities, the same thresholds are lower by 10/5 mmHg, i.e., 110/65 mmHg for the asleep means. In high-risk patients, including those diagnosed with diabetes or chronic kidney disease, and/or those having experienced past

  9. A model for simulating autoclave-reactor pressure histories

    SciTech Connect

    Thorsness, C.B.

    1995-11-01

    Small heated-batch reactors, frequently referred to as autoclave reactors, are often used in developing information for a proposed new chemical/physical processing step. These systems often entail considerable pressure buildup during the course of operation. This report describes a model formulated to simulate well mixed autoclave reactors. The model solves a system of differential and algebraic equations which describe vapor/liquid equilibrium and chemical reactions in the reactor during a heating and cooling cycle. The model allows any number of chemical species to be defined. Phase equilibrium considerations are limited to systems with one liquid and one vapor phase, although some provisions for dealing with a second pure water liquid phase are considered. Equilibrium constraints are formulated using fugacity and activity coefficients. A new version of the general purpose differential-algebraic system solver DASSL, called DASPK, has been used to solve the system of equations. This solver has been found to work well in test problems. Selected results from a number of example problems are described. The example systems are water/nitrogen; crude oil/water; hexane/toluene; hexane/heptadecane; water/carbon dioxide; and a biomass system.

  10. Probabilistic Modeling Of Ocular Biomechanics In VIIP: Risk Stratification

    NASA Technical Reports Server (NTRS)

    Feola, A.; Myers, J. G.; Raykin, J.; Nelson, E. S.; Mulugeta, L.; Samuels, B.; Ethier, C. R.

    2016-01-01

    Visual Impairment and Intracranial Pressure (VIIP) syndrome is a major health concern for long-duration space missions. Currently, it is thought that a cephalad fluid shift in microgravity causes elevated intracranial pressure (ICP) that is transmitted along the optic nerve sheath (ONS). We hypothesize that this in turn leads to alteration and remodeling of connective tissue in the posterior eye which impacts vision. Finite element (FE) analysis is a powerful tool for examining the effects of mechanical loads in complex geometries. Our goal is to build a FE analysis framework to understand the response of the lamina cribrosa and optic nerve head to elevations in ICP in VIIP. To simulate the effects of different pressures on tissues in the posterior eye, we developed a geometric model of the posterior eye and optic nerve sheath and used a Latin hypercubepartial rank correlation coef-ficient (LHSPRCC) approach to assess the influence of uncertainty in our input parameters (i.e. pressures and material properties) on the peak strains within the retina, lamina cribrosa and optic nerve. The LHSPRCC approach was repeated for three relevant ICP ranges, corresponding to upright and supine posture on earth, and microgravity [1]. At each ICP condition we used intraocular pressure (IOP) and mean arterial pressure (MAP) measurements of in-flight astronauts provided by Lifetime Surveillance of Astronaut Health Program, NASA Johnson Space Center. The lamina cribrosa, optic nerve, retinal vessel and retina were modeled as linear-elastic materials, while other tissues were modeled as a Mooney-Rivlin solid (representing ground substance, stiffness parameter c1) with embedded collagen fibers (stiffness parameters c3, c4 and c5). Geometry creationmesh generation was done in Gmsh [2], while FEBio was used for all FE simulations [3]. The LHSPRCC approach resulted in correlation coefficients in the range of 1. To assess the relative influence of the uncertainty in an input parameter on

  11. Assessing the goodness of fit of personal risk models.

    PubMed

    Gong, Gail; Quante, Anne S; Terry, Mary Beth; Whittemore, Alice S

    2014-08-15

    We describe a flexible family of tests for evaluating the goodness of fit (calibration) of a pre-specified personal risk model to the outcomes observed in a longitudinal cohort. Such evaluation involves using the risk model to assign each subject an absolute risk of developing the outcome within a given time from cohort entry and comparing subjects' assigned risks with their observed outcomes. This comparison involves several issues. For example, subjects followed only for part of the risk period have unknown outcomes. Moreover, existing tests do not reveal the reasons for poor model fit when it occurs, which can reflect misspecification of the model's hazards for the competing risks of outcome development and death. To address these issues, we extend the model-specified hazards for outcome and death, and use score statistics to test the null hypothesis that the extensions are unnecessary. Simulated cohort data applied to risk models whose outcome and mortality hazards agreed and disagreed with those generating the data show that the tests are sensitive to poor model fit, provide insight into the reasons for poor fit, and accommodate a wide range of model misspecification. We illustrate the methods by examining the calibration of two breast cancer risk models as applied to a cohort of participants in the Breast Cancer Family Registry. The methods can be implemented using the Risk Model Assessment Program, an R package freely available at http://stanford.edu/~ggong/rmap/.

  12. Toxic industrial chemical (TIC) source emissions modeling for pressurized liquefied gases

    NASA Astrophysics Data System (ADS)

    Britter, Rex; Weil, Jeffrey; Leung, Joseph; Hanna, Steven

    2011-01-01

    The objective of this article is to report current toxic industrial chemical (TIC) source emissions formulas appropriate for use in atmospheric comprehensive risk assessment models so as to represent state-of-the-art knowledge. The focus is on high-priority scenarios, including two-phase releases of pressurized liquefied gases such as chlorine from rail cars. The total mass released and the release duration are major parameters, as well as the velocity, thermodynamic state, and amount and droplet sizes of imbedded aerosols of the material at the exit of the rupture, which are required as inputs to the subsequent jet and dispersion modeling. Because of the many possible release scenarios that could develop, a suite of model equations has been described. These allow for gas, two-phase or liquid storage and release through ruptures of various types including sharp-edged and "pipe-like" ruptures. Model equations for jet depressurization and phase change due to flashing are available. Consideration of the importance of vessel response to a rupture is introduced. The breakup of the jet into fine droplets and their subsequent suspension and evaporation, or rainout is still a significant uncertainty in the overall modeling process. The recommended models are evaluated with data from various TIC field experiments, in particular recent experiments with pressurized liquefied gases. It is found that there is typically a factor of two error in models compared with research-grade observations of mass flow rates. However, biases are present in models' estimates of the droplet size distributions resulting from flashing releases.

  13. Does low diastolic blood pressure contribute to the risk of recurrent hypertensive cardiovascular disease events? The Framingham Heart Study.

    PubMed

    Franklin, Stanley S; Gokhale, Sohum S; Chow, Vincent H; Larson, Martin G; Levy, Daniel; Vasan, Ramachandran S; Mitchell, Gary F; Wong, Nathan D

    2015-02-01

    Whether low diastolic blood pressure (DBP) is a risk factor for recurrent cardiovascular disease (CVD) events in persons with isolated systolic hypertension is controversial. We studied 791 individuals (mean age 75 years, 47% female, mean follow-up time: 8±6 years) with DBP <70 (n=225) versus 70 to 89 mm Hg (n=566) after initial CVD events in the original and offspring cohorts of the Framingham Heart Study. Recurrent CVD events occurred in 153 (68%) participants with lower DBP and 271 (48%) with higher DBP (P<0.0001). Risk of recurrent CVD events in risk factor-adjusted Cox regression was higher in those with DBP <70 mm Hg versus DBP 70 to 89 mm Hg in both treated (hazard ratio, 5.1 [95% confidence interval: 3.8-6.9] P<0.0001) and untreated individuals (hazard ratio, 11.7 [95% confidence interval: 6.5-21.1] P<0.0001; treatment interaction: P=0.71). Individually, coronary heart disease, heart failure, and stroke recurrent events were more likely with DBP <70 mm Hg versus 70 to 89 mm Hg (P<0.0001). To examine for an effect of wide pulse pressure on excess risk associated with low DBP, we defined 4 binary groupings of pulse pressure (≥68 versus <68 mm Hg) and DBP (<70 versus 70-89 mm Hg). CVD incidence rates were higher only in the group with pulse pressure ≥68 and DBP <70 mm Hg (76% versus 46%-54%; P<0.001). Persons with isolated systolic hypertension and prior CVD events have increased risk for recurrent CVD events in the presence of DBP <70 mm Hg versus DBP 70 to 89 mm Hg, whether treated or untreated, supporting wide pulse pressure as an important risk modifier for the adverse effect of low DBP.

  14. Development of a Pressure-Dependent Constitutive Model with Combined Multilinear Kinematic and Isotropic Hardening

    NASA Technical Reports Server (NTRS)

    Allen Phillip A.; Wilson, Christopher D.

    2003-01-01

    The development of a pressure-dependent constitutive model with combined multilinear kinematic and isotropic hardening is presented. The constitutive model is developed using the ABAQUS user material subroutine (UMAT). First the pressure-dependent plasticity model is derived. Following this, the combined bilinear and combined multilinear hardening equations are developed for von Mises plasticity theory. The hardening rule equations are then modified to include pressure dependency. The method for implementing the new constitutive model into ABAQUS is given.

  15. Modeling biotic habitat high risk areas

    USGS Publications Warehouse

    Despain, D.G.; Beier, P.; Tate, C.; Durtsche, B.M.; Stephens, T.

    2000-01-01

    Fire, especially stand replacing fire, poses a threat to many threatened and endangered species as well as their habitat. On the other hand, fire is important in maintaining a variety of successional stages that can be important for approach risk assessment to assist in prioritizing areas for allocation of fire mitigation funds. One example looks at assessing risk to the species and biotic communities of concern followed by the Colorado Natural Heritage Program. One looks at the risk to Mexican spottled owls. Another looks at the risk to cutthroat trout, and a fourth considers the general effects of fire and elk.

  16. SMALL POPULATIONS REQUIRE SPECIFIC MODELING APPROACHES FOR ASSESSING RISK

    EPA Science Inventory

    All populations face non-zero risks of extinction. However, the risks for small populations, and therefore the modeling approaches necessary to predict them, are different from those of large populations. These differences are currently hindering assessment of risk to small pop...

  17. A new explained-variance based genetic risk score for predictive modeling of disease risk.

    PubMed

    Che, Ronglin; Motsinger-Reif, Alison A

    2012-09-25

    The goal of association mapping is to identify genetic variants that predict disease, and as the field of human genetics matures, the number of successful association studies is increasing. Many such studies have shown that for many diseases, risk is explained by a reasonably large number of variants that each explains a very small amount of disease risk. This is prompting the use of genetic risk scores in building predictive models, where information across several variants is combined for predictive modeling. In the current study, we compare the performance of four previously proposed genetic risk score methods and present a new method for constructing genetic risk score that incorporates explained variance information. The methods compared include: a simple count Genetic Risk Score, an odds ratio weighted Genetic Risk Score, a direct logistic regression Genetic Risk Score, a polygenic Genetic Risk Score, and the new explained variance weighted Genetic Risk Score. We compare the methods using a wide range of simulations in two steps, with a range of the number of deleterious single nucleotide polymorphisms (SNPs) explaining disease risk, genetic modes, baseline penetrances, sample sizes, relative risks (RR) and minor allele frequencies (MAF). Several measures of model performance were compared including overall power, C-statistic and Akaike's Information Criterion. Our results show the relative performance of methods differs significantly, with the new explained variance weighted GRS (EV-GRS) generally performing favorably to the other methods.

  18. The Risk of Intraocular Pressure Elevation in Pediatric Non-infectious Uveitis

    PubMed Central

    Kothari, Srishti; Foster, C. Stephen; Pistilli, Maxwell; Liesegang, Teresa L.; Daniel, Ebenezer; Sen, H. Nida; Suhler, Eric B.; Thorne, Jennifer E.; Jabs, Douglas A.; Levy-Clarke, Grace A.; Nussenblatt, Robert B.; Rosenbaum, James T.; Lawrence, Scott D.; Kempen, John H.

    2015-01-01

    Purpose To characterize the risk and risk factors for intraocular pressure (IOP) elevation in pediatric non-infectious uveitis. Design Multi-center retrospective cohort study. Participants Nine hundred sixteen children (1593 eyes) <18 years old at presentation with non-infectious uveitis followed between January 1978 through December 2007 at five academic uveitis centers in United States. Methods Medical records review by trained, certified experts. Main outcome measures Prevalence and incidence of IOP≥21 and ≥30mmHg and incidence of a rise in IOP by ≥10mmHg. To avoid under ascertainment, outcomes were counted as present when IOP-lowering therapies were in use. Results Initially 251 (15.8%) and 46 eyes (2.9%) had IOP≥21 and ≥30mmHg, respectively. Factors associated with presenting IOP elevation included age 6–12 years (versus other pediatric ages), prior cataract surgery (adjusted odds ratio≥21mmHg [aOR21]=2.42, P=0.01), pars plana vitrectomy (adjusted odds ratio≥30mmHg[aOR30]=11.1, P=0.03), duration of uveitis ≥6 months (aORs30 up to 11.8, P<0.001), contralateral IOP elevation (aOR21=16.9, aOR30=8.29; each P<0.001), visual acuity worse than 20/40 (aORs21 up to 1.73, P=0.02; aORs30 up to 2.81 P=0.03), and topical corticosteroid use (aORs up to 8.92, P<0.001 in a dose-response relationship). The median follow-up was 1.25 years (interquartile range 0.4–3.66). The estimated risk of any observed IOP elevation to ≥21 mmHg, ≥30 mmHg and of a rise in IOP by ≥10mmHg was 33.4%, 14.8% and 24.4% respectively within 2 years. Factors associated with IOP elevation included pars plana vitrectomy (adjusted hazard ratio≥21mmHg[aHR21]=3.36, P<0.001), contralateral IOP elevation (aHRs up to 9.54, P<0.001), the use of topical (aHRs up to 8.77 that followed a dose-response relationship, P<0.001), periocular (aHRs up to 7.96, P<0.001) and intraocular (aHRs up to 19.7, P<0.001) corticosteroids. Conclusions IOP elevation affects a large minority of children

  19. Linking Self-Regulation and Risk Proneness to Risky Sexual Behavior: Pathways through Peer Pressure and Early Substance Use

    ERIC Educational Resources Information Center

    Crockett, Lisa J.; Raffaelli, Marcela; Shen, Yuh-Ling

    2006-01-01

    The linkages between self-regulation in childhood, risk proneness in early adolescence, and risky sexual behavior in mid-adolescence were examined in a cohort of children (N=518) from the National Longitudinal Survey of Youth. The possible mediating role of two early adolescent variables (substance use and negative peer pressure) was also…

  20. Identity Development as a Buffer of Adolescent Risk Behaviors in the Context of Peer Group Pressure and Control

    ERIC Educational Resources Information Center

    Dumas, Tara M.; Ellis, Wendy E.; Wolfe, David A.

    2012-01-01

    We examined identity development as a moderator of the relation between peer group pressure and control and adolescents' engagement in risk behaviors. Participants (n = 1070; M[subscript age] = 15.45 years) completed a self-report measure of "identity exploration", the degree to which they have explored a variety of self-relevant values, beliefs…

  1. School-Based Exercise to Lower Blood Pressure in High-Risk African American Girls: Project Design and Baseline Findings.

    ERIC Educational Resources Information Center

    Ewart, Craig K.; And Others

    1995-01-01

    Describes effective methods for identifying and recruiting high risk African American ninth-grade girls to measure their fitness and assess the impact of fitness training on blood pressure. A multistage step test for fitness assessment in such girls is presented. The "Project Heart" aerobics class and control groups are described. (SM)

  2. Peak Sound Pressure Levels and Associated Auditory Risk from an H[subscript 2]-Air "Egg-Splosion"

    ERIC Educational Resources Information Center

    Dolhun, John J.

    2016-01-01

    The noise level from exploding chemical demonstrations and the effect they could have on audiences, especially young children, needs attention. Auditory risk from H[subscript 2]- O2 balloon explosions have been studied, but no studies have been done on H[subscript 2]-air "eggsplosions." The peak sound pressure level (SPL) was measured…

  3. Pressure Ulcer Risk and Prevention Practices in Pediatric Patients: A Secondary Analysis of Data from the National Database of Nursing Quality Indicators®.

    PubMed

    Razmus, Ivy; Bergquist-Beringer, Sandra

    2017-01-01

    Little is known about pressure ulcer prevention practice among pediatric patients. To describe the frequency of pressure ulcer risk assessment in pediatric patients and pressure ulcer prevention intervention use overall and by hospital unit type, a descriptive secondary analysis was performed of data submitted to the National Database for Nursing Quality Indicators® (NDNQI®) for at least 3 of the 4 quarters in 2012. Relevant data on pressure ulcer risk from 271 hospitals across the United States extracted from the NDNQI database included patient skin and pressure ulcer risk assessment on admission, time since the last pressure ulcer risk assessment, method used to assess pressure ulcer risk, and risk status. Extracted data on pressure ulcer prevention included skin assessment, pressure-redistribution surface use, routine repositioning, nutritional support, and moisture management. These data were organized by unit type and merged with data on hospital characteristics for the analysis. The sample included 39 984 patients ages 1 day to 18 years on 678 pediatric acute care units (general pediatrics, pediatric critical care units, neonatal intensive care units, pediatric step-down units, and pediatric rehabilitation units). Descriptive statistics were used to analyze study data. Most of the pediatric patients (33 644; 89.2%) were assessed for pressure ulcer risk within 24 hours of admission. The Braden Q Scale was frequently used to assess risk on general pediatrics units (75.4%), pediatric step-down units (85.5%), pediatric critical care units (81.3%), and pediatric rehabilitation units (56.1%). In the neonatal intensive care units, another scale or method was used more often (55% to 60%) to assess pressure ulcer risk. Of the 11 203 pediatric patients (39%) determined to be at risk for pressure ulcers, the majority (10 741, 95.8%) received some kind of pressure ulcer prevention intervention during the 24 hours preceding the NDNQI pressure ulcer survey. The frequency

  4. Design and research on reliability-validity for 3S intraoperative risk assessment scale of pressure sore.

    PubMed

    Gao, Xing-lian; Hu, Juan-juan; Ma, Qiong; Wu, He-yu; Wang, Zeng-yan; Li, Ting-ting; Shen, Jian-hui; Yang, Ying

    2015-04-01

    The reliability and validity of risk assessment scale (RAS) of pressure sore during 3S surgery were investigated. RAS of pressure sore was designed independently during 3S surgery. Five operating room nursing experts were selected to consult and detect face validity. Convenient and purposive sampling of 707 samples was conducted. Cronbach's alpha was used to measure content reliability and evaluate the internal consistence of RAS. The structural reliability was investigated by exploratory factor analysis method. The results showed that the content validity index was 0.92, and Cronbach's alpha of content reliability was 0.71. Structural validity, detected by Bartlett sphericity test, was 135.3 for 707 samples with the difference being statistically significant (P<0.01). KMO value was 0.729. The accumulative variance contribution ratio of common factor was 64.63%. The exploratory factor analysis showed the factor load of every clause was larger than 0.596. It was concluded that RAS of pressure sore for 3S surgery has better validity and reliability, and it could be used for evaluating and screening the high risk patients with pressure sores during surgery in order to efficiently reduce the occurrence of pressure sore during surgery. RAS of pressure sore for 3S surgery is worth to be popularized.

  5. Ambulatory blood pressure monitoring in diabetes for the assessment and control of vascular risk.

    PubMed

    Hermida, Ramón C; Moyá, Ana; Ayala, Diana E

    2015-10-01

    The diagnosis of hypertension and the clinical decisions regarding its treatment are usually based on daytime clinic blood pressure (BP) measurements. However, the correlation between BP levels and target organ damage, cardiovascular (CV) risk, and long-term prognosis, is higher for ambulatory (ABPM) than clinic measurements, both in the general population as well as in patients with diabetes. Moreover, there is consistent evidence in numerous studies that the asleep BP better predicts CV events than either the awake or 24h means. The prevalence of abnormal BP pattern and sleep-time hypertension is extensive in diabetes, often leading to inaccurate diagnoses of hypertension and its therapeutic control in the absence of complete and careful assessment of the entire 24h, i.e., daytime and night-time, BP pattern. Accordingly, ABPM should be the preferred method to comprehensively assess and decide the optimal clinical management of patients with diabetes directed to properly reduce elevated sleep-time BP, which might also lead to a significant reduction of CV events.

  6. Risk management modeling and its application in maritime safety

    NASA Astrophysics Data System (ADS)

    Qin, Ting-Rong; Chen, Wei-Jiong; Zeng, Xiang-Kun

    2008-12-01

    Quantified risk assessment (QRA) needs mathematicization of risk theory. However, attention has been paid almost exclusively to applications of assessment methods, which has led to neglect of research into fundamental theories, such as the relationships among risk, safety, danger, and so on. In order to solve this problem, as a first step, fundamental theoretical relationships about risk and risk management were analyzed for this paper in the light of mathematics, and then illustrated with some charts. Second, man-machine-environment-management (MMEM) theory was introduced into risk theory to analyze some properties of risk. On the basis of this, a three-dimensional model of risk management was established that includes: a goal dimension; a management dimension; an operation dimension. This goal management operation (GMO) model was explained and then emphasis was laid on the discussion of the risk flowchart (operation dimension), which lays the groundwork for further study of risk management and qualitative and quantitative assessment. Next, the relationship between Formal Safety Assessment (FSA) and Risk Management was researched. This revealed that the FSA method, which the international maritime organization (IMO) is actively spreading, comes from Risk Management theory. Finally, conclusion were made about how to apply this risk management method to concrete fields efficiently and conveniently, as well as areas where further research is required.

  7. Optimistic Bias, Risk Factors, and Development of High Blood Pressure and Obesity among African American Adolescents in Mississippi (USA).

    PubMed

    White, Monique S; Addison, Clifton C; Jenkins, Brenda W Campbell; Bland, Vanessa; Clark, Adrianne; LaVigne, Donna Antoine

    2017-02-20

    Childhood obesity has reached epidemic proportions and is linked to hypertension among African American youth. Optimistic bias influences behavior of youth causing them to underestimate their susceptibility to negative health outcomes. This study explored adolescent behaviors and prevalence of high blood pressure and obesity in a school district. We examined the relationship between individual health risk practices and optimistic bias on health outcomes; 433 African American high school students were administered a survey and had their obesity and blood pressure measured by the school nurse. Canonical correlational analyses were used to examine relationships between health risk practices and descriptive statistics for optimistic bias and health outcomes. Engaging in moderate exercise for at least 30 min in the last 7 days and lower blood pressure was the only statistically significant relationship. Two-thirds of the students did not perceive themselves to be at risk of developing cardiovascular disease with males at greater risk than females, despite the presence of clinical risk factors for hypertension and obesity. Reducing health optimistic bias is an effective way of motivating young people to adopt more positive behaviors using educational institutions to implement intervention programs that promote positive health behavior as a way to reduce health disparities.

  8. Optimistic Bias, Risk Factors, and Development of High Blood Pressure and Obesity among African American Adolescents in Mississippi (USA)

    PubMed Central

    White, Monique S.; Addison, Clifton C.; Campbell Jenkins, Brenda W.; Bland, Vanessa; Clark, Adrianne; Antoine LaVigne, Donna

    2017-01-01

    Childhood obesity has reached epidemic proportions and is linked to hypertension among African American youth. Optimistic bias influences behavior of youth causing them to underestimate their susceptibility to negative health outcomes. This study explored adolescent behaviors and prevalence of high blood pressure and obesity in a school district. We examined the relationship between individual health risk practices and optimistic bias on health outcomes; 433 African American high school students were administered a survey and had their obesity and blood pressure measured by the school nurse. Canonical correlational analyses were used to examine relationships between health risk practices and descriptive statistics for optimistic bias and health outcomes. Engaging in moderate exercise for at least 30 min in the last 7 days and lower blood pressure was the only statistically significant relationship. Two-thirds of the students did not perceive themselves to be at risk of developing cardiovascular disease with males at greater risk than females, despite the presence of clinical risk factors for hypertension and obesity. Reducing health optimistic bias is an effective way of motivating young people to adopt more positive behaviors using educational institutions to implement intervention programs that promote positive health behavior as a way to reduce health disparities. PMID:28230728

  9. Multi-dimensional modeling of pressurization and expulsion of multi-phase hydrogen propellant

    NASA Technical Reports Server (NTRS)

    1993-01-01

    A multidimensional computational model of the pressurization process in a slush hydrogen propellant storage tank was developed and its accuracy evaluated by comparison to experimental data measured for a 5 ft diameter spherical tank. The fluid mechanic, thermodynamic, and heat transfer processes within the ullage are represented by a finite-volume model. the heat and mass fluxes at the ullage boundary were computed in auxiliary analyses and specified as input to the finite-volume model. the model was shown to be in reasonable agreement with the experimental data. A parameter study was undertaken to examine the dependence of the pressurization process on initial ullage temperature distribution and pressurant mass flow rate. It is shown that for a given heat flux rate at the ullage boundary, the pressurization process is nearly independent of initial temperature distribution. The mass flow rate study revealed decreasing pressurant mass requirements with increasing pressurant mass flow rate. Further, significant differences were identified between the ullage temperature and velocity fields predicted for pressurization of slush and those predicted for pressurization of liquid hydrogen. A simplified model of the pressurization process was constructed in search of a dimensionless characterization of the pressurization process. It is shown that the relationship derived from this simplified model collapses all of the pressure history data generated during this study into a single curve.

  10. Model for avalanches in a hollow pressure filament

    NASA Astrophysics Data System (ADS)

    Poulos, M. J.; Morales, G. J.

    2016-10-01

    A theoretical and modeling study is made of a novel heating configuration recently implemented in the LAPD device at UCLA. The geometry essentially consists of a hollow pressure filament embedded in a cold, magnetized plasma. An eigenmode-based stability analysis is made of drift-waves excited by simultaneous gradients in density and temperature. A Braginskii transport code that includes the ExB flows of the unstable modes is used to self-consistently evolve the profile modifications in the presence of external heating. A shooting code is used to calculate the evolving mode structures as the profiles are modified. It is found that intermittent avalanches are triggered and their properties are in good agreement with the experimental observations. During the recovery phase after an avalanche the large difference between the relaxation times of density and temperature results in azimuthal filamentation of the profiles. New insights are obtained that suggest future laboratory and theoretical studies. Sponsored by BaPSF at UCLA under DOE-NSF Grant.

  11. Kinetic modeling study of toluene pyrolysis at low pressure

    SciTech Connect

    Zhang, Lidong; Cai, Jianghuai; Zhang, Taichang; Qi, Fei

    2010-09-15

    A detailed kinetic model, consisting of 137 species and 530 reactions, was developed to simulate toluene pyrolysis at low pressure within the temperature range from 1270 to 1870 K. The mole fraction profiles predicted for pyrolysis species up to phenanthrene were in good agreement with the experiment. The decomposition pathways of toluene and the growth pathways to polycyclic aromatic hydrocarbons (PAHs) were discussed from reaction flux analysis. Toluene decomposes through the reaction sequence C{sub 6}H{sub 5}CH{sub 3}{yields} C{sub 6}H{sub 5}CH{sub 2}{yields}C{sub 7}H{sub 6}{yields}c-C{sub 5}H{sub 5}{yields}C{sub 3}H{sub 3}, which also has a predominant contribution to the production of acetylene. Furthermore, sensitivity analysis showed that the primary decomposition reactions of toluene, C{sub 6}H{sub 5}CH{sub 3}=C{sub 6}H{sub 5}CH{sub 2}+H and C{sub 6}H{sub 5}CH{sub 3}=C{sub 6}H{sub 5}+CH{sub 3}, have great influences on the formation of small molecules, such as phenyl radical, benzyl radical, C2- and C3-species, which are critical to the formation of PAHs in the pyrolysis of toluene. (author)

  12. Concentration of Risk Model (CORM) Verification and Analysis

    DTIC Science & Technology

    2014-06-15

    Mental Health and using data from a repository at the University of Michigan, had attempted to identify soldiers at higher-than-average risk of suicide ...TRAC-M-TR-14-023 15 June 2014 Concentration of Risk Model (CORM) Verification and Analysis TRADOC Analysis Center - Monterey 700 Dyer Road Monterey...TRAC-M-TR-14-023 15 June 2014 Concentration of Risk Model (CORM) Verification and Analysis Edward M. Masotti Sam Buttrey TRADOC Analysis Center

  13. Assessing complexity of skin blood flow oscillations in response to locally applied heating and pressure in rats: Implications for pressure ulcer risk

    NASA Astrophysics Data System (ADS)

    Liao, Fuyuan; O'Brien, William D.; Jan, Yih-Kuen

    2013-10-01

    The objective of this study was to investigate the effects of local heating on the complexity of skin blood flow oscillations (BFO) under prolonged surface pressure in rats. Eleven Sprague-Dawley rats were studied: 7 rats underwent surface pressure with local heating (△t=10 °C) and 4 rats underwent pressure without heating. A pressure of 700 mmHg was applied to the right trochanter area of rats for 3 h. Skin blood flow was measured using laser Doppler flowmetry. The loading period was divided into nonoverlapping 30 min epochs. For each epoch, multifractal detrended fluctuation analysis (MDFA) was utilized to compute DFA coefficients and complexity of endothelial related metabolic, neurogenic, and myogenic frequencies of BFO. The results showed that under surface pressure, local heating led to a significant decrease in DFA coefficients of myogenic frequency during the initial epoch of loading period, a sustained decrease in complexity of myogenic frequency, and a significantly higher degree of complexity of metabolic frequency during the later phase of loading period. Surrogate tests showed that the reduction in complexity of myogenic frequency was associated with a loss of nonlinearity whereas increased complexity of metabolic frequency was associated with enhanced nonlinearity. Our results indicate that increased metabolic activity and decreased myogenic response due to local heating manifest themselves not only in magnitudes of metabolic and myogenic frequencies but also in their structural complexity. This study demonstrates the feasibility of using complexity analysis of BFO to monitor the ischemic status of weight-bearing skin and risk of pressure ulcers.

  14. A risk analysis model for radioactive wastes.

    PubMed

    Külahcı, Fatih

    2011-07-15

    Hazardous wastes affect natural environmental systems to a significant extend, and therefore, it is necessary to control their harm through risk analysis. Herein, an effective risk methodology is proposed by considering their uncertain behaviors on stochastic, statistical and probabilistic bases. The basic element is attachment of a convenient probability distribution function (pdf) to a given waste quality measurement sequence. In this paper, (40)K contaminant measurements are adapted for risk assessment application after derivation of necessary fundamental formulations. The spatial contaminant distribution of (40)K is presented in the forms of maps and three-dimensional surfaces.

  15. [Model for early childhood caries risks].

    PubMed

    Dimitrova, M; Kukleva, M

    2008-01-01

    Risk factors of early childhood caries were studied on 406 children of 12-47 months age. The results showed that pathological pregnancy, sleeping with bottle of blend or sweet liquid, use of candy and caramel on sticks and sour-sweet fruit juices were significant factors leading to early childhood caries. During simultaneous action of all these risk factors domination belonged to use of sour-sweet fruit juices. The probability of caries occurrence at simultaneous action of all these risk factors was equal to 62%.

  16. State-of-Art Empirical Modeling of Ring Current Plasma Pressure

    NASA Astrophysics Data System (ADS)

    Yue, C.; Ma, Q.; Wang, C. P.; Bortnik, J.; Thorne, R. M.

    2015-12-01

    The plasma pressure in the inner magnetosphere plays a key role in plasma dynamics by changing magnetic field configurations and generating the ring current. In this study, we present our preliminary results of empirically constructing 2D equatorial ring current pressure and pressure anisotropy spatial distributions controlled by Dst based on measurements from two particle instruments (HOPE and RBSPICE) onboard Van Allen Probes. We first obtain the equatorial plasma perpendicular and parallel pressures for different species including H+, He+, O+ and e- from 20 eV to ~1 MeV, and investigate their relative contributions to the total plasma pressure and pressure anisotropy. We then establish empirical equatorial pressure models within ~ 6 RE using a state-of-art machine learning technique, Support Vector Regression Machine (SVRM). The pressure models predict equatorial perpendicular and parallel plasma thermal pressures (for each species and for total pressures) and pressure anisotropy at any given r, MLT, Bz/Br (equivalent Z distance), and Dst within applicable ranges. We are currently validating our model predictions and investigating how the ring current pressure distributions and the associated pressure gradients vary with Dst index.

  17. Source-to-Outcome Microbial Exposure and Risk Modeling Framework

    EPA Science Inventory

    A Quantitative Microbial Risk Assessment (QMRA) is a computer-based data-delivery and modeling approach that integrates interdisciplinary fate/transport, exposure, and impact models and databases to characterize potential health impacts/risks due to pathogens. As such, a QMRA ex...

  18. Integrating Household Risk Mitigation Behavior in Flood Risk Analysis: An Agent-Based Model Approach.

    PubMed

    Haer, Toon; Botzen, W J Wouter; de Moel, Hans; Aerts, Jeroen C J H

    2016-11-28

    Recent studies showed that climate change and socioeconomic trends are expected to increase flood risks in many regions. However, in these studies, human behavior is commonly assumed to be constant, which neglects interaction and feedback loops between human and environmental systems. This neglect of human adaptation leads to a misrepresentation of flood risk. This article presents an agent-based model that incorporates human decision making in flood risk analysis. In particular, household investments in loss-reducing measures are examined under three economic decision models: (1) expected utility theory, which is the traditional economic model of rational agents; (2) prospect theory, which takes account of bounded rationality; and (3) a prospect theory model, which accounts for changing risk perceptions and social interactions through a process of Bayesian updating. We show that neglecting human behavior in flood risk assessment studies can result in a considerable misestimation of future flood risk, which is in our case study an overestimation of a factor two. Furthermore, we show how behavior models can support flood risk analysis under different behavioral assumptions, illustrating the need to include the dynamic adaptive human behavior of, for instance, households, insurers, and governments. The method presented here provides a solid basis for exploring human behavior and the resulting flood risk with respect to low-probability/high-impact risks.

  19. Incisional Negative Pressure Wound Therapy in High Risk Patients Undergoing Panniculectomy: A Prospective Randomized Controlled Trial

    ClinicalTrials.gov

    2017-01-03

    Complications Wounds; Negative Pressure Wound Therapy; Wound Healing Delayed; Incisional; Panniculectomy; Incisional Negative Pressure Wound Therapy; Incisional Vac; Wound Vac; Obese; Renal Failure; Kidney Transplant; Complications; Wound Healing Complication

  20. Physical activity levels and torso orientations of hospitalized patients at risk of developing a pressure injury: an observational study.

    PubMed

    Chaboyer, Wendy; Mills, Peter M; Roberts, Shelley; Latimer, Sharon

    2015-02-01

    Pressure injury guidelines recommend regular repositioning yet patients' mobility and repositioning patterns are unknown. An observational study using activity monitors was undertaken to describe the 24 h activity patterns of 84 hospitalized patients at risk of developing a pressure injury. The vast majority of participants' time was spent in the sedentary activity range (94% ± 3%) followed by the light range (5% ± 4 %). Patients changed their posture a median of 94 (interquartile range 48) time in the 24-h period (range 11-154), or ≈ 3.8 times per hour. Although a main focus for pressure injury prevention has been on repositioning, this study shows that patients with restricted mobility are actually moving quite often. Therefore, it might be appropriate to focus more attention on other pressure injury prevention strategies such as adequate nutrition, appropriate support surfaces and good skin care.

  1. In-line pressure-flow module for in vitro modelling of haemodynamics and biosensor validation

    NASA Technical Reports Server (NTRS)

    Koenig, S. C.; Schaub, J. D.; Ewert, D. L.; Swope, R. D.; Convertino, V. A. (Principal Investigator)

    1997-01-01

    An in-line pressure-flow module for in vitro modelling of haemodynamics and biosensor validation has been developed. Studies show that good accuracy can be achieved in the measurement of pressure and of flow, in steady and pulstile flow systems. The model can be used for development, testing and evaluation of cardiovascular-mechanical-electrical anlogue models, cardiovascular prosthetics (i.e. valves, vascular grafts) and pressure and flow biosensors.

  2. X-33 Metal Model Testing In Low Turbulence Pressure Tunnel

    NASA Technical Reports Server (NTRS)

    1997-01-01

    The countrys next generation of space transportation, a reusable launch vehicle (RLV), continues to undergo wind tunnel testing at NASA Langley Research Center, Hampton, Va. All four photos are a metal model of the X-33 reusable launch vehicle (about 15 inches long by 15 inches wide) being tested for Lockheed Martin Skunk Works in the Low Turbulence Pressure Tunnel (LTPT) at NASA Langley Research Center. Tests are being conducted by members of the Aerothermodynamics Branch. According to Kelly Murphy of Langleys Aerothermodynamics Branch, the aluminum and stainless steel model of the X-33 underwent aerodynamic testing in the tunnel. *The subsonic tests were conducted at the speed of Mach 25,* she said. *Force and moment testing and measurement in this tunnel lasted about one week.* Future testing of the metal model is scheduled for Langleys 16-Foot Transonic Tunnel, from the end of March to mid-April 1997, and the Unitary Wind Tunnel, from mid-April to the beginning of May. Other tunnel testing for X-33 models are scheduled from the present through June in the hypersonic tunnels, and the 14- by 22-Foot Tunnel from about mid-June to mid-July. Since 1991 Marshall Space Flight Center in Huntsville, Ala. has been the lead center for coordinating the Agencys X-33 Reusable Launch Vehicle (RLV) Program, an industry-led effort, which NASA Administrator Daniel S. Goldin has declared the agency's highest priority new program. The RLV Technology Program is a partnership among NASA, the United States Air Force and private industry to develop world leadership in low-cost space transportation. The goal of the program is to develop technologies and new operational concepts that can radically reduce the cost of access to space. The RLV program also hopes to speed the commercialization of space and improve U.S. economic competitiveness by making access to space as routine and reliable as today's airline industry, while reducing costs and enhancing safety and reliability. The RLV

  3. X-33 Metal Model Testing In Low Turbulence Pressure Tunnel

    NASA Technical Reports Server (NTRS)

    1997-01-01

    The countrys next generation of space transportation, a reusable launch vehicle (RLV), continues to undergo wind tunnel testing at NASA Langley Research Center, Hampton, Va. All four photos are a metal model of the X-33 reusable launch vehicle (about 15 inches long by 15 inches wide) being tested for Lockheed Martin Skunk Works in the Low Turbulence Pressure Tunnel (LTPT) at NASA Langley Research Center. Tests are being conducted by members of the Aerothermodynamics Branch. According to Kelly Murphy of Langleys Aerothermodynamics Branch, the aluminum and stainless steel model of the X-33 underwent aerodynamic testing in the tunnel. *The subsonic tests were conducted at the speed of Mach .25,* she said. *Force and moment testing and measurement in this tunnel lasted about one week.* Future testing of the metal model is scheduled for Langleys 16-Foot Transonic Tunnel, from the end of March to mid-April 1997, and the Unitary Wind Tunnel, from mid-April to the beginning of May. Other tunnel testing for X-33 models are scheduled from the present through June in the hypersonic tunnels, and the 14- by 22-Foot Tunnel from about mid-June to mid-July. Since 1991 Marshall Space Flight Center in Huntsville, Ala. has been the lead center for coordinating the Agencys X-33 Reusable Launch Vehicle (RLV) Program, an industry-led effort, which NASA Administrator Daniel S. Goldin has declared the agency's highest priority new program. The RLV Technology Program is a partnership among NASA, the United States Air Force and private industry to develop world leadership in low-cost space transportation. The goal of the program is to develop technologies and new operational concepts that can radically reduce the cost of access to space. The RLV program also hopes to speed the commercialization of space and improve U.S. economic competitiveness by making access to space as routine and reliable as today's airline industry, while reducing costs and enhancing safety and reliability. The RLV

  4. Extended risk-analysis model for activities of the project.

    PubMed

    Kušar, Janez; Rihar, Lidija; Zargi, Urban; Starbek, Marko

    2013-12-01

    Project management of product/service orders has become a mode of operation in many companies. Although these are mostly cyclically recurring projects, risk management is very important for them. An extended risk-analysis model for new product/service projects is presented in this paper. Emphasis is on a solution developed in the Faculty of Mechanical Engineering in Ljubljana, Slovenia. The usual project activities risk analysis is based on evaluation of the probability that risk events occur and on evaluation of their consequences. A third parameter has been added in our model: an estimate of the incidence of risk events. On the basis of the calculated activity risk level, a project team prepares preventive and corrective measures that should be taken according to the status indicators. An important advantage of the proposed solution is that the project manager and his team members are timely warned of risk events and they can thus activate the envisaged preventive and corrective measures as necessary.

  5. A new pressure formulation for gas-compressibility dampening in bubble dynamics models.

    PubMed

    Gadi Man, Yezaz Ahmed; Trujillo, Francisco J

    2016-09-01

    We formulated a pressure equation for bubbles performing nonlinear radial oscillations under ultrasonic high pressure amplitudes. The proposed equation corrects the gas pressure at the gas-liquid interface on inertial bubbles. This pressure formulation, expressed in terms of gas-Mach number, accounts for dampening due to gas compressibility during the violent collapse of cavitation bubbles and during subsequent rebounds. We refer to this as inhomogeneous pressure, where the gas pressure at the gas-liquid interface can differ to the pressure at the centre of the bubble, in contrast to homogenous pressure formulations that consider that pressure inside the bubble is spatially uniform from the wall to the centre. The pressure correction was applied to two bubble dynamic models: the incompressible Rayleigh-Plesset equation and the compressible Keller and Miksis equation. This improved the predictions of the nonlinear radial motion of the bubble vs time obtained with both models. Those simulations were also compared with other bubble dynamics models that account for liquid and gas compressibility effects. It was found that our corrected models are in closer agreement with experimental data than alternative models. It was concluded that the Rayleigh-Plesset family of equations improve accuracy by using our proposed pressure correction.

  6. Reassessment of Ambulatory Blood Pressure Improves Renal Risk Stratification in Nondialysis Chronic Kidney Disease: Long-Term Cohort Study.

    PubMed

    Minutolo, Roberto; Gabbai, Francis B; Chiodini, Paolo; Garofalo, Carlo; Stanzione, Giovanna; Liberti, Maria Elena; Pacilio, Mario; Borrelli, Silvio; Provenzano, Michele; Conte, Giuseppe; De Nicola, Luca

    2015-09-01

    In nondialysis chronic kidney disease, ambulatory blood pressure (ABP) performs better than clinic BP in predicting outcome, but whether repeated assessment of ABP further refines prognosis remains ill-defined. We recruited 182 consecutive hypertensive patients with nondialysis chronic kidney disease who underwent 2 ABPs 12 months apart to evaluate the enhancement in risk stratification provided by a second ABP obtained 1 year after baseline on the risk (hazard ratio and 95% confidence interval) of composite renal end point (death, chronic dialysis, and estimated glomerular filtration rate decline ≥40%). The difference in daytime and nighttime systolic BP between the 2 ABPs (daytime and nighttime bias) was added to a survival model including baseline ABP. Net reclassification improvement was also calculated. Age was 65.6±13.4 years; 36% had diabetes mellitus and 36% had previous cardiovascular event; estimated glomerular filtration rate was 42.2±19.6 mL/min per 1.73 m(2), and clinic BP was 145±18/80±11 mm Hg. Baseline ABP (daytime, 131±16/75±10 and nighttime, 122±18/66±10 mm Hg) and daytime/nighttime BP goals (58.2% and 43.4%) did not change at month 12. Besides baseline ABP values, bias for daytime and nighttime systolic BP linearly associated with renal outcome (1.12, 1.04-1.21 and 1.18, 1.08-1.29 for every 5-mm Hg increase, respectively). Classification of patients at risk improved when considering nighttime systolic level at second ABP (net reclassification improvement, 0.224; 95% confidence interval, 0.005-0.435). Patients with first and second ABPs above target showed greater renal risk (2.15, 1.29-3.59 and 1.71, 1.07-2.72, for daytime and nighttime, respectively). In nondialysis chronic kidney disease, reassessment of ABP at 1 year further refines renal prognosis; such reassessment should specifically be considered in patients with uncontrolled BP at baseline.

  7. Quantified Risk Ranking Model for Condition-Based Risk and Reliability Centered Maintenance

    NASA Astrophysics Data System (ADS)

    Chattopadhyaya, Pradip Kumar; Basu, Sushil Kumar; Majumdar, Manik Chandra

    2016-03-01

    In the recent past, risk and reliability centered maintenance (RRCM) framework is introduced with a shift in the methodological focus from reliability and probabilities (expected values) to reliability, uncertainty and risk. In this paper authors explain a novel methodology for risk quantification and ranking the critical items for prioritizing the maintenance actions on the basis of condition-based risk and reliability centered maintenance (CBRRCM). The critical items are identified through criticality analysis of RPN values of items of a system and the maintenance significant precipitating factors (MSPF) of items are evaluated. The criticality of risk is assessed using three risk coefficients. The likelihood risk coefficient treats the probability as a fuzzy number. The abstract risk coefficient deduces risk influenced by uncertainty, sensitivity besides other factors. The third risk coefficient is called hazardous risk coefficient, which is due to anticipated hazards which may occur in the future and the risk is deduced from criteria of consequences on safety, environment, maintenance and economic risks with corresponding cost for consequences. The characteristic values of all the three risk coefficients are obtained with a particular test. With few more tests on the system, the values may change significantly within controlling range of each coefficient, hence `random number simulation' is resorted to obtain one distinctive value for each coefficient. The risk coefficients are statistically added to obtain final risk coefficient of each critical item and then the final rankings of critical items are estimated. The prioritization in ranking of critical items using the developed mathematical model for risk assessment shall be useful in optimization of financial losses and timing of maintenance actions.

  8. General circulation model simulations of winter and summer sea-level pressures over North America

    USGS Publications Warehouse

    McCabe, G.J.; Legates, D.R.

    1992-01-01

    In this paper, observed sea-level pressures were used to evaluate winter and summer sea-level pressures over North America simulated by the Goddard Institute for Space Studies (GISS) and the Geophysical Fluid Dynamics Laboratory (GFDL) general circulation models. The objective of the study is to determine how similar the spatial and temporal distributions of GCM-simulated daily sea-level pressures over North America are to observed distributions. Overall, both models are better at reproducing observed within-season variance of winter and summer sea-level pressures than they are at simulating the magnitude of mean winter and summer sea-level pressures. -from Authors

  9. Evaluation of cluster recovery for small area relative risk models.

    PubMed

    Rotejanaprasert, Chawarat

    2014-12-01

    The analysis of disease risk is often considered via relative risk. The comparison of relative risk estimation methods with "true risk" scenarios has been considered on various occasions. However, there has been little examination of how well competing methods perform when the focus is clustering of risk. In this paper, a simulated evaluation of a range of potential spatial risk models and a range of measures that can be used for (a) cluster goodness of fit, (b) cluster diagnostics are considered. Results suggest that exceedence probability is a poor measure of hot spot clustering because of model dependence, whereas residual-based methods are less model dependent and perform better. Local deviance information criteria measures perform well, but conditional predictive ordinate measures yield a high false positive rate.

  10. A Team Mental Model Perspective of Pre-Quantitative Risk

    NASA Technical Reports Server (NTRS)

    Cooper, Lynne P.

    2011-01-01

    This study was conducted to better understand how teams conceptualize risk before it can be quantified, and the processes by which a team forms a shared mental model of this pre-quantitative risk. Using an extreme case, this study analyzes seven months of team meeting transcripts, covering the entire lifetime of the team. Through an analysis of team discussions, a rich and varied structural model of risk emerges that goes significantly beyond classical representations of risk as the product of a negative consequence and a probability. In addition to those two fundamental components, the team conceptualization includes the ability to influence outcomes and probabilities, networks of goals, interaction effects, and qualitative judgments about the acceptability of risk, all affected by associated uncertainties. In moving from individual to team mental models, team members employ a number of strategies to gain group recognition of risks and to resolve or accept differences.

  11. Numerical modeling of self-pressurization and pressure control by a thermodynamic vent system in a cryogenic tank

    NASA Astrophysics Data System (ADS)

    Majumdar, Alok; Valenzuela, Juan; LeClair, Andre; Moder, Jeff

    2016-03-01

    This paper presents a numerical model of a system-level test bed-the multipurpose hydrogen test bed (MHTB) using the Generalized Fluid System Simulation Program (GFSSP). MHTB is representative in size and shape of a space transportation vehicle liquid hydrogen propellant tank, and ground-based testing was performed at NASA Marshall Space Flight Center (MSFC) to generate data for cryogenic storage. GFSSP is a finite volume-based network flow analysis software developed at MSFC and used for thermofluid analysis of propulsion systems. GFSSP has been used to model the self-pressurization and ullage pressure control by the Thermodynamic Vent System (TVS). A TVS typically includes a Joule-Thompson (J-T) expansion device, a two-phase heat exchanger (HEX), and a mixing pump and liquid injector to extract thermal energy from the tank without significant loss of liquid propellant. For the MHTB tank, the HEX and liquid injector are combined into a vertical spray bar assembly. Two GFSSP models (Self-Pressurization and TVS) were separately developed and tested and then integrated to simulate the entire system. The Self-Pressurization model consists of multiple ullage nodes, a propellant node, and solid nodes; it computes the heat transfer through multilayer insulation blankets and calculates heat and mass transfer between the ullage and liquid propellant and the ullage and tank wall. A TVS model calculates the flow through a J-T valve, HEX, and spray and vent systems. Two models are integrated by exchanging data through User Subroutines of both models. Results of the integrated models have been compared with MHTB test data at a 50% fill level. Satisfactory comparison was observed between tests and numerical predictions.

  12. CODE's new solar radiation pressure model for GNSS orbit determination

    NASA Astrophysics Data System (ADS)

    Arnold, D.; Meindl, M.; Beutler, G.; Dach, R.; Schaer, S.; Lutz, S.; Prange, L.; Sośnica, K.; Mervart, L.; Jäggi, A.

    2015-08-01

    The Empirical CODE Orbit Model (ECOM) of the Center for Orbit Determination in Europe (CODE), which was developed in the early 1990s, is widely used in the International GNSS Service (IGS) community. For a rather long time, spurious spectral lines are known to exist in geophysical parameters, in particular in the Earth Rotation Parameters (ERPs) and in the estimated geocenter coordinates, which could recently be attributed to the ECOM. These effects grew creepingly with the increasing influence of the GLONASS system in recent years in the CODE analysis, which is based on a rigorous combination of GPS and GLONASS since May 2003. In a first step we show that the problems associated with the ECOM are to the largest extent caused by the GLONASS, which was reaching full deployment by the end of 2011. GPS-only, GLONASS-only, and combined GPS/GLONASS solutions using the observations in the years 2009-2011 of a global network of 92 combined GPS/GLONASS receivers were analyzed for this purpose. In a second step we review direct solar radiation pressure (SRP) models for GNSS satellites. We demonstrate that only even-order short-period harmonic perturbations acting along the direction Sun-satellite occur for GPS and GLONASS satellites, and only odd-order perturbations acting along the direction perpendicular to both, the vector Sun-satellite and the spacecraft's solar panel axis. Based on this insight we assess in the third step the performance of four candidate orbit models for the future ECOM. The geocenter coordinates, the ERP differences w. r. t. the IERS 08 C04 series of ERPs, the misclosures for the midnight epochs of the daily orbital arcs, and scale parameters of Helmert transformations for station coordinates serve as quality criteria. The old and updated ECOM are validated in addition with satellite laser ranging (SLR) observations and by comparing the orbits to those of the IGS and other analysis centers. Based on all tests, we present a new extended ECOM which

  13. Analysis of self-pressurization phenomenon of cryogenic fluid storage tank with thermal diffusion model

    NASA Astrophysics Data System (ADS)

    Seo, Mansu; Jeong, Sangkwon

    2010-09-01

    Self-pressurization phenomenon is one of the most important problems in the storage of cryogenic liquid. Until now, it has been difficult to predict exact pressurization process due to its complex non-equilibrium thermal behavior. This paper analyzes the self-pressurization with the trend of pressurization curves from experiment using liquid nitrogen with various heat leaks and liquid fractions. The trend of pressurization curves are classified on the basis of shape of pressurization curve. The qualitative relation between transient period, heat leak and liquid fractions is suggested. Thermal diffusion model (TDM) considering thermal stratification and thermal equilibrium model (TEM) can properly predict the respective pressurization curves with suitable condition for each model.

  14. A comprehensive Network Security Risk Model for process control networks.

    PubMed

    Henry, Matthew H; Haimes, Yacov Y

    2009-02-01

    The risk of cyber attacks on process control networks (PCN) is receiving significant attention due to the potentially catastrophic extent to which PCN failures can damage the infrastructures and commodity flows that they support. Risk management addresses the coupled problems of (1) reducing the likelihood that cyber attacks would succeed in disrupting PCN operation and (2) reducing the severity of consequences in the event of PCN failure or manipulation. The Network Security Risk Model (NSRM) developed in this article provides a means of evaluating the efficacy of candidate risk management policies by modeling the baseline risk and assessing expectations of risk after the implementation of candidate measures. Where existing risk models fall short of providing adequate insight into the efficacy of candidate risk management policies due to shortcomings in their structure or formulation, the NSRM provides model structure and an associated modeling methodology that captures the relevant dynamics of cyber attacks on PCN for risk analysis. This article develops the NSRM in detail in the context of an illustrative example.

  15. Intervention models for mothers and children at risk for injuries.

    PubMed

    Gulotta, C S; Finney, J W

    2000-03-01

    We review risk factors commonly associated with childhood unintentional injuries and highlight adolescent mothers and their young children as a high risk group. Several intervention models of injury, including the epidemiological model, Peterson and Brown's "working model," and the socioecological model have been proposed to explain the events that lead to injuries. Discussion of these models is provided and a synthesis of the adolescent parenting model and the socioecological model of injury is suggested as way to address the complex variables that lead to an injury causing event for adolescent mothers and their young children. Finally, we suggest areas of future investigation and their implications for prevention and treatment.

  16. Modeling and simulation of a class of liquid propellant engine pressurization systems

    NASA Astrophysics Data System (ADS)

    Karimi, H.; Nassirharand, Amir; Mohseni, M.

    2010-02-01

    In this paper, a new approach for modeling a class of pressurization systems for liquid propellant engines is presented. High pressure gas stored in special capsules is injected in a controlled way onto the gas volume on top of the propellant tanks. Instantaneous pressure and temperature values of propellant tanks and the capsules are computed. The computed constitutive values are compared with experimental results. The modeling approach accounts for variations of pressure and density of the pressurant inside the capsules and propellant tanks. It also accounts for heat transfer between pressurant and its surroundings. Equations for determination of the pressurant shut-down time are developed. Similarly, equations for determination of the propellant pump inlet pressure are also derived. The final governing equations are in terms of a set of differential equations that are numerically solved using the modified Euler method. The primary application of this research is to determine the pressurization system exit pressure. In case of turbo-pump feed systems, this work may be used to detect the occurrence of the cavitation phenomenon in the pumps. The method is limited to: (1) thermally insulated propellant tanks and (2) use of several storage capsules that are made of insulating composite material (i.e., exit mass flow rate is small, pressurant is stored at high pressure and low volume, temperature variations are small, and pressure drop in the capsules is not appreciable).

  17. The effects of vehicle model and driver behavior on risk.

    PubMed

    Wenzel, Thomas P; Ross, Marc

    2005-05-01

    We study the dependence of risk on vehicle type and especially on vehicle model. Here, risk is measured by the number of driver fatalities per year per million vehicles registered. We analyze both the risk to the drivers of each vehicle model and the risk the vehicle model imposes on drivers of other vehicles with which it crashes. The "combined risk" associated with each vehicle model is simply the sum of the risk-to-drivers in all kinds of crashes and the risk-to-drivers-of-other-vehicles in two-vehicle crashes. We find that most car models are as safe to their drivers as most sport utility vehicles (SUVs); the increased risk of a rollover in a SUV roughly balances the higher risk for cars that collide with SUVs and pickup trucks. We find that SUVs and to a greater extent pickup trucks, impose much greater risks than cars on drivers of other vehicles; and these risks increase with increasing pickup size. The higher aggressivity of SUVs and pickups makes their combined risk higher than that of almost all cars. Effects of light truck design on their risk are revealed by the analysis of specific models: new unibody (or "crossover") SUVs appear, in preliminary analysis, to have much lower risks than the most popular truck-based SUVs. Much has been made in the past about the high risk of low-mass cars in certain kinds of collisions. We find there are other plausible explanations for this pattern of risk, which suggests that mass may not be fundamental to safety. While not conclusive, this is potentially important because improvement in fuel economy is a major goal for designers of new vehicles. We find that accounting for the most risky drivers, young males and the elderly, does not change our general results. Similarly, we find with California data that the high risk of rural driving and the high level of rural driving by pickups does not increase the risk-to-drivers of pickups relative to that for cars. However, other more subtle differences in drivers and the

  18. [Identification of subjects at high risk of coronary disease in a working population using a prediction model].

    PubMed

    Laurier, D; Chau, N P

    1995-11-01

    Identification of subjects at high risk of coronary morbidity is of major interest in the prevention of cardiovascular disease. This report describes the use of a multifactorial prediction model for the identification of high risk subjects in a French male population. The PCV-METRA study (Prévention Cardiovasculaire en Médecine du Travail) monitors risk factors of cardiovascular morbidity in a population of men and women employed in big companies in the Paris region. A model adapted from a prediction model conceived by K.M. Anderson et al. in the Framingham study was used. The modified model enables an estimation of individual coronary risk based on 7 factors: age, total cholesterol, HDL-cholesterol, systolic blood pressure, smoking, diabetes and presence of left ventricular hypertrophy, taking into account the relatively low prevalence of coronary heart disease in France. The population comprised 4,131 active men aged 30 to 65 years. The average risk at 5 years was estimated to be 1.6%. Subjects at high risk (over the 80th percentile of the risk distribution curve) usually had high blood pressures and cholesterol levels. However, nearly 30% of these subjects were neither hypertensive nor hypercholesteraemic. It is important to note that 3/4 of these smoked. Moreover, they also had low HDL-cholesterol levels. A risk table, derived from the Framingham model, is presented. This table allows estimation of individual risk at 5 years in men aged 30 to 65 years. In each age group, the comparison of individual risk with the percentiles of risk distribution in the PCV-METRA population allows identification of high-risk subjects. This study proposes a tool for identifying subjects at high risk of coronary morbidity in a French male population. This multifactorial model is particularly useful for detecting subjects with several borderline factors none of which overstep the usually accepted limits.

  19. Risk factors for obesity and high blood pressure in Chinese American children: maternal acculturation and children's food choices.

    PubMed

    Chen, Jyu-Lin; Weiss, Sandra; Heyman, Melvin B; Lustig, Robert

    2011-04-01

    The objective of this study is to explore risk factors associated with overweight and high blood pressure in Chinese American children. Students and their parents were recruited from Chinese language schools in the San Francisco Bay Area. Data were collected on 67 children and their mothers, and included children's weight, height, waist and hip circumferences, blood pressure, level of physical activity, dietary intake, usual food choice, knowledge about nutrition and physical activity, and self-efficacy regarding diet and physical activity. Mothers completed questionnaires on demographic data and acculturation. About 46% of children had a body mass index exceeding the 85th percentile. Lower level of maternal acculturation is a risk factor for overweight and higher waist to hip ratio. Children's unhealthy food choices were predictive of high body mass index and high systolic blood pressure, whereas older age and less physical activity in children were predictors of high diastolic blood pressure. Developing culturally sensitive and developmentally appropriate interventions to reduce overweight and high blood pressure is critical to reduce health disparities among minority children.

  20. Unsteady Pressure Measurements on Oscillating Models in European Wind Tunnels.

    DTIC Science & Technology

    1980-03-01

    EFFECTIVE TUBE DIAMETER 1.5 * EXPERIMENT 0j 1. 0. Frequency ,Hz 50 100 1*50 200 1500 2000 Figure 1 Experimental and Theoretical Results for a Single i...NORA 17 III CONCLUDING REMARKS 18* IV REFERENCES 19 P7 ,.-- ii i 7 LIST OF ILLUSTRATIONS FIGURE PAGE 1 Experimental and Theoretical Results for a...and Experimental Centerline Pressures in Chordwise Bending 71 48 Rigid Wing with Oscillating Control Surface 72 49 Supersonic Pressure Due to Control

  1. Measurement of the Pressure Distribution on Two Model Propellers

    DTIC Science & Technology

    1982-07-01

    dynamometer. This dynamometer system uses two 500 hp (0.372 MW) electric drive motors located in a pod attached to thp- 3ower end of a strut. The test...the laboratory without the 1000 hp dynamometer cabling and sliprings connected through the measurement system. The propeller pressure gages were...process. 9 I I The final calibrations used during the test were conducted in the laboratory with water in the pressure tank and gage cavities. A

  2. Nighttime home blood pressure and the risk of hypertensive target organ damage.

    PubMed

    Ishikawa, Joji; Hoshide, Satoshi; Eguchi, Kazuo; Ishikawa, Shizukiyo; Shimada, Kazuyuki; Kario, Kazuomi

    2012-10-01

    In ambulatory blood pressure (BP) monitoring, nighttime BP has a superior ability to predict hypertensive target organ damage than awake BP. We evaluated whether nighttime BP, assessed by a home BP monitor, was associated with hypertensive target organ damage. We measured clinic BP, out-of-clinic BP including nighttime home BP, and the urinary albumin:creatinine ratio (UACR) in 854 patients who had cardiovascular risk factors. Nighttime home BP was measured at 2:00, 3:00, and 4:00 am, in addition to clinic, awake ambulatory, nighttime ambulatory, and awake home BP. Nighttime home systolic BP (SBP) was slightly higher than nighttime ambulatory SBP (difference, 2.6 mm Hg; P<0.001). Clinic (r=0.186), awake ambulatory (r=0.173), nighttime ambulatory (r=0.194), awake home (r=0.298), and nighttime home (r=0.311) SBPs were all associated with log-transformed UACR (all P<0.001). The correlation coefficient for the relationship between nighttime home SBP and log-transformed UACR was significantly greater than that for the relationship between nighttime ambulatory SBP and log-transformed UACR (P<0.001). The goodness of fit of the association between SBP and UACR was improved by adding nighttime home SBP to the other SBPs (P<0.001). Nighttime home diastolic BP also improved the goodness-of-fit of the association between diastolic BP and UACR (P=0.001). Similar findings were observed for the left ventricular mass index in the subgroup (N=594). In conclusion, nighttime home BP is slightly different from (but comparable to) nighttime ambulatory BP. The addition of nighttime home BP to other BP measures improves the association of BP with hypertensive target organ damage.

  3. Quantification of finger joint loadings using musculoskeletal modelling clarifies mechanical risk factors of hand osteoarthritis.

    PubMed

    Goislard de Monsabert, Benjamin; Vigouroux, Laurent; Bendahan, David; Berton, Eric

    2014-02-01

    Owing to limited quantitative data related to the loadings (forces and pressures) acting upon finger joints, several clinical observations regarding mechanical risk factors of hand osteoarthritis remain misunderstood. To improve the knowledge of this pathology, the present study used musculoskeletal modelling to quantify the forces and pressures acting upon hand joints during two grasping tasks. Kinematic and grip force data were recorded during both a pinch and a power grip tasks. Three-dimensional magnetic resonance imaging measurements were conducted to quantify joint contact areas. Using these datasets as input, a musculoskeletal model of the hand and wrist, including twenty-three degrees of freedom and forty-two muscles, has been developed to estimate joint forces and joint pressures. When compared with the power grip task, the pinch grip task resulted in two to eight times higher joint loadings whereas the grip forces exerted on each finger were twice lower. For both tasks, joint forces and pressures increased along a disto-proximal direction for each finger. The quantitative dataset provided by the present hand model clarified two clinical observations about osteoarthritis development which were not fully understood, i.e., the strong risk associated to pinch grip tasks and the high frequency of thumb-base osteoarthritis.

  4. Individualized Risk Prediction Model for Lung Cancer in Korean Men

    PubMed Central

    Park, Sohee; Nam, Byung-Ho; Yang, Hye-Ryung; Lee, Ji An; Lim, Hyunsun; Han, Jun Tae; Park, Il Su; Shin, Hai-Rim; Lee, Jin Soo

    2013-01-01

    Purpose Lung cancer is the leading cause of cancer deaths in Korea. The objective of the present study was to develop an individualized risk prediction model for lung cancer in Korean men using population-based cohort data. Methods From a population-based cohort study of 1,324,804 Korean men free of cancer at baseline, the individualized absolute risk of developing lung cancer was estimated using the Cox proportional hazards model. We checked the validity of the model using C statistics and the Hosmer–Lemeshow chi-square test on an external validation dataset. Results The risk prediction model for lung cancer in Korean men included smoking exposure, age at smoking initiation, body mass index, physical activity, and fasting glucose levels. The model showed excellent performance (C statistic = 0.871, 95% CI = 0.867–0.876). Smoking was significantly associated with the risk of lung cancer in Korean men, with a four-fold increased risk in current smokers consuming more than one pack a day relative to non-smokers. Age at smoking initiation was also a significant predictor for developing lung cancer; a younger age at initiation was associated with a higher risk of developing lung cancer. Conclusion This is the first study to provide an individualized risk prediction model for lung cancer in an Asian population with very good model performance. In addition to current smoking status, earlier exposure to smoking was a very important factor for developing lung cancer. Since most of the risk factors are modifiable, this model can be used to identify those who are at a higher risk and who can subsequently modify their lifestyle choices to lower their risk of lung cancer. PMID:23408946

  5. High Pressure Coolant Injection (HPCI) System Risk-Based Inspection Guide for Browns Ferry Nuclear Power Station

    SciTech Connect

    Wong, S.; DiBiasio, A.; Gunther, W.

    1993-09-01

    The High Pressure Coolant Injection (HPCI) system has been examined from a risk perspective. A System Risk-Based Inspection Guide (S-RIG) has been developed as an aid to HPCI system inspections at the Browns Ferry Nuclear Power Plant, Units 1, 2 and 3. The role of. the HPCI system in mitigating accidents is discussed in this S-RIG, along with insights on identified risk-based failure modes which could prevent proper operation of the system. The S-RIG provides a review of industry-wide operating experience, including plant-specific illustrative examples to augment the PRA and operational considerations in identifying a catalogue of basic PRA failure modes for the HPCI system. It is designed to be used as a reference for routine inspections, self-initiated safety system functional inspections (SSFIs), and the evaluation of risk significance of component failures at the nuclear power plant.

  6. Assessing Academic Risk of Student-Athletes: Applicability of the NCAA Graduation Risk Overview Model to GPA

    ERIC Educational Resources Information Center

    Johnson, James

    2013-01-01

    In an effort to standardize academic risk assessment, the NCAA developed the graduation risk overview (GRO) model. Although this model was designed to assess graduation risk, its ability to predict grade-point average (GPA) remained unknown. Therefore, 134 individual risk assessments were made to determine GRO model effectiveness in the…

  7. Comparison of three computational models for predicting pressurization characteristics of cryogenic tank during discharge

    NASA Astrophysics Data System (ADS)

    Lei, Wang; Yanzhong, Li; Kang, Zhu; Yonghua, Jin

    2015-01-01

    In order to select an effective approach to predict the pressurization characteristics of cryogenic tank during rocket launching, three computational models, defined as 0-D, 1-D and CFD models, are used to obtain the pressure evolution and thermal performance of a cryogenic tank during pressurized discharge period. Several pressurization cases are computed by all of the three models to evaluate their predictive abilities and effects, respectively. The comparative study shows that for the case with a diffuser-type injector at the tank inlet, the consistent results by the three models are obtained in the most of period, except that 1-D model has a peak departure prediction of pressure value at the beginning of process. All of the three models can be used to predict the pressurization performance, and their predictive abilities could be validated with one another. The CFD model is the unique suitable model to display the pressurization performance including physical distribution in radial direction especially for the system with no-diffuser-type injector. Based on the analysis, the application selection of three models for different cases is accomplished. The 0-D model is the priority selection for a simple pressure prediction of tank ullage, even for the situation that severe temperature distribution exists in the ullage range. The 1-D model is the optimal selection as considering both the convenience and the time consumption for the constant-pressure cases. But it is not recommended in a constant-inlet flux cases for its distinct predicting deviation at the beginning of the process. When the detailed distributions within the tank are concerned, the CFD model is the unique selection. The results of this paper may be beneficial to the model selection and optimization analysis of a pressurization system.

  8. Constitutive and damage material modeling in a high pressure hydrogen environment

    NASA Technical Reports Server (NTRS)

    Russell, D. A.; Fritzemeier, L. G.

    1991-01-01

    Numerous components in reusable space propulsion systems such as the SSME are exposed to high pressure gaseous hydrogen environments. Flow areas and passages in the fuel turbopump, fuel and oxidizer preburners, main combustion chamber, and injector assembly contain high pressure hydrogen either high in purity or as hydrogen rich steam. Accurate constitutive and damage material models applicable to high pressure hydrogen environments are therefore needed for engine design and analysis. Existing constitutive and cyclic crack initiation models were evaluated only for conditions of oxidizing environments. The main objective is to evaluate these models for applicability to high pressure hydrogen environments.

  9. Physically-based strength model of tantalum incorporating effects of temperature, strain rate and pressure

    DOE PAGES

    Lim, Hojun; Battaile, Corbett C.; Brown, Justin L.; ...

    2016-06-14

    In this work, we develop a tantalum strength model that incorporates e ects of temperature, strain rate and pressure. Dislocation kink-pair theory is used to incorporate temperature and strain rate e ects while the pressure dependent yield is obtained through the pressure dependent shear modulus. Material constants used in the model are parameterized from tantalum single crystal tests and polycrystalline ramp compression experiments. It is shown that the proposed strength model agrees well with the temperature and strain rate dependent yield obtained from polycrystalline tantalum experiments. Furthermore, the model accurately reproduces the pressure dependent yield stresses up to 250 GPa.more » The proposed strength model is then used to conduct simulations of a Taylor cylinder impact test and validated with experiments. This approach provides a physically-based multi-scale strength model that is able to predict the plastic deformation of polycrystalline tantalum through a wide range of temperature, strain and pressure regimes.« less

  10. Physically-based strength model of tantalum incorporating effects of temperature, strain rate and pressure

    SciTech Connect

    Lim, Hojun; Battaile, Corbett C.; Brown, Justin L.; Weinberger, Christopher R.

    2016-06-14

    In this work, we develop a tantalum strength model that incorporates e ects of temperature, strain rate and pressure. Dislocation kink-pair theory is used to incorporate temperature and strain rate e ects while the pressure dependent yield is obtained through the pressure dependent shear modulus. Material constants used in the model are parameterized from tantalum single crystal tests and polycrystalline ramp compression experiments. It is shown that the proposed strength model agrees well with the temperature and strain rate dependent yield obtained from polycrystalline tantalum experiments. Furthermore, the model accurately reproduces the pressure dependent yield stresses up to 250 GPa. The proposed strength model is then used to conduct simulations of a Taylor cylinder impact test and validated with experiments. This approach provides a physically-based multi-scale strength model that is able to predict the plastic deformation of polycrystalline tantalum through a wide range of temperature, strain and pressure regimes.

  11. Risk models and scores for type 2 diabetes: systematic review

    PubMed Central

    Mathur, Rohini; Dent, Tom; Meads, Catherine; Greenhalgh, Trisha

    2011-01-01

    Objective To evaluate current risk models and scores for type 2 diabetes and inform selection and implementation of these in practice. Design Systematic review using standard (quantitative) and realist (mainly qualitative) methodology. Inclusion criteria Papers in any language describing the development or external validation, or both, of models and scores to predict the risk of an adult developing type 2 diabetes. Data sources Medline, PreMedline, Embase, and Cochrane databases were searched. Included studies were citation tracked in Google Scholar to identify follow-on studies of usability or impact. Data extraction Data were extracted on statistical properties of models, details of internal or external validation, and use of risk scores beyond the studies that developed them. Quantitative data were tabulated to compare model components and statistical properties. Qualitative data were analysed thematically to identify mechanisms by which use of the risk model or score might improve patient outcomes. Results 8864 titles were scanned, 115 full text papers considered, and 43 papers included in the final sample. These described the prospective development or validation, or both, of 145 risk prediction models and scores, 94 of which were studied in detail here. They had been tested on 6.88 million participants followed for up to 28 years. Heterogeneity of primary studies precluded meta-analysis. Some but not all risk models or scores had robust statistical properties (for example, good discrimination and calibration) and had been externally validated on a different population. Genetic markers added nothing to models over clinical and sociodemographic factors. Most authors described their score as “simple” or “easily implemented,” although few were specific about the intended users and under what circumstances. Ten mechanisms were identified by which measuring diabetes risk might improve outcomes. Follow-on studies that applied a risk score as part of an

  12. Global flood risk modelling and its applications for disaster risk reduction

    NASA Astrophysics Data System (ADS)

    Jongman, Brenden; Winsemius, Hessel; Bierkens, Marc; Bouwman, Arno; van Beek, Rens; Ligtvoet, Willem; Ward, Philip

    2014-05-01

    Flooding of river systems is the most costly natural hazard affecting societies around the world, with an average of 55 billion in direct losses and 4,500 fatalities each year between 1990 and 2012. The accurate and consistent assessment of flood risk on a global scale is essential for international development organizations and the reinsurance industry, and for enhancing our understanding of climate change impacts. This need is especially felt in developing countries, where local data and models are largely unavailable, and where flood risk is increasing rapidly under strong population growth and economic development. Here we present ongoing applications of high-resolution flood risk modelling at a global scale. The work is based on GLOFRIS, a modelling chain that produces flood risk maps at a 1km spatial resolution for the entire globe, under a range of climate and socioeconomic scenarios and various past and future time periods. This modelling chain combines a hydrological inundation model with socioeconomic datasets to assess past, current and future population exposure; economic damages; and agricultural risk. These tools are currently applied scientifically to gain insights in geographical patterns in current risk, and to assess the effects of possible future scenarios under climate change and climate variability. In this presentation we show recent applications from global scale to national scales. The global scale applications include global risk profiling for the reinsurance industry; and novel estimation of global flood mortality risk. In addition it will be demonstrated how the global flood modelling approach was successfully applied to assess disaster risk reduction priorities on a national scale in Africa. Finally, we indicate how these global modelling tools can be used to quantify the costs and benefits of adaptation, and explore pathways for development under a changing environment.

  13. The ability of rock physics models to infer marine in situ pore pressure

    NASA Astrophysics Data System (ADS)

    Hornbach, Matthew J.; Manga, Michael

    2014-12-01

    fluid pressure is an important parameter defining the mechanical strength of marine sediments. Obtaining high spatial resolution in situ pore pressure measurements in marine sediments, however, is a challenge, and as a result, only a handful of in situ pore pressure measurements exist at scientific drill sites. Integrating rock physics models with standard IODP/ODP measurements provides a potentially widely applicable approach for calculating in situ pore pressure. Here we use a rock physics approach to estimate in situ pore pressure at two Scientific Ocean Drill Sites where in situ pressure is well constrained: ODP Site 1173, used as reference for normal (hydrostatic) fluid pressures, and ODP Site 948, where previous studies infer high fluid pressures (λ* ˜ 0.45-0.95, where the pore pressure ratio λ* is defined as the pore pressure above hydrostatic divided by the difference between the largest principal stress and hydrostatic stress). Our analysis indicates that the rock physics method provides an accurate, low-precision method for estimating in situ pore pressure at these drill sites, and sensitivity analysis indicates this method can detect modestly high (λ* > 0.6) pore pressure at the 95% confidence level. This approach has broad applicability because it provides an inexpensive, high-resolution (meter-scale) method for retrospectively detecting and quantifying high pore pressure at any drill site where quality wireline logs and ocean drilling data exist.

  14. Sleep-time blood pressure: prognostic value and relevance as a therapeutic target for cardiovascular risk reduction.

    PubMed

    Hermida, Ramón C; Ayala, Diana E; Fernández, José R; Mojón, Artemio

    2013-03-01

    Correlation between blood pressure (BP) level and target organ damage, cardiovascular disease (CVD) risk, and long-term prognosis is greater for ambulatory BP monitoring (ABPM) than clinical BP measurements. Nevertheless, the latter continue to be the "gold standard" to diagnose hypertension, assess CVD risk, and evaluate hypertension treatment. Independent ABPM studies have found that elevated sleep-time BP is a better predictor of CVD risk than either the awake or 24-h BP mean. A major limitation of all previous ABPM-based prognostic studies is the reliance only upon a single baseline profile from each participant at the time of inclusion, without accounting for potential changes in the level and pattern of ambulatory BP thereafter during follow-up. Accordingly, impact of the alteration over time, i.e., during long-term follow-up, of specific features of the 24-h BP variation on CVD risk has never been properly investigated. We evaluated the comparative prognostic value of (i) clinic and ambulatory BP; (ii) different ABPM-derived characteristics, e.g., asleep or awake BP mean; and (iii) specific changes in ABPM characteristic during follow-up, mainly whether reduced CVD risk is more related to the progressive decrease of asleep or awake BP. We prospectively studied 3344 subjects (1718 men/1626 women), 52.6 ± 14.5 (mean ± SD) yrs of age, during a median follow-up of 5.6 yrs. Those with hypertension at baseline were randomized to ingest all their prescribed hypertension medications upon awakening or ≥1 of them at bedtime. At baseline, BP was measured at 20-min intervals from 07:00 to 23:00 h and at 30-min intervals at night for 48-h, and physical activity was simultaneously monitored every min by wrist actigraphy to accurately derive awake and asleep BP means. Identical assessment was scheduled annually and more frequently (quarterly) if treatment adjustment was required. Data collected either at baseline or the last ABPM evaluation per participant

  15. Analytic Modeling of Pressurization and Cryogenic Propellant Conditions for Lunar Landing Vehicle

    NASA Technical Reports Server (NTRS)

    Corpening, Jeremy

    2010-01-01

    This slide presentation reviews the development, validation and application of the model to the Lunar Landing Vehicle. The model named, Computational Propellant and Pressurization Program -- One Dimensional (CPPPO), is used to model in this case cryogenic propellant conditions of the Altair Lunar lander. The validation of CPPPO was accomplished via comparison to an existing analytic model (i.e., ROCETS), flight experiment and ground experiments. The model was used to the Lunar Landing Vehicle perform a parametric analysis on pressurant conditions and to examine the results of unequal tank pressurization and draining for multiple tank designs.

  16. The OPTIONS model of sexual risk assessment for adolescents.

    PubMed

    Lusczakoski, Kathryn D; Rue, Lisa A

    2012-03-01

    Typically, clinical evaluations of adolescents' sexual risk is based on inquiring about past sexual activity, which is limited by not including an adolescent's cognitive decision making regarding their past sexual decisions. This study describes the novel OPTIONS framework for assessing adolescent sexual risk including three general categories of risk (e.g., primary, secondary, and tertiary risk), which is designed to overcome the limitation of action-based assessment of risk and improve practitioners' ability to assess the levels of sexual risk. A convenience sample of 201 older adolescents (18-19 years of age) completed an online version of the Relationship Options Survey (ROS), designed to measure the OPTIONS sexual risk assessment. Bivariate correlation among the subscales functioned in the hypothesized manner, with all correlations being statistically significant. Using the OPTIONS model, 22.4% participants were classified as high risk primary, 7.0% participants were classified as high risk secondary, and 27.4% participants were classified as high risk tertiary. The study provided preliminary evidence for OPTIONS model of sexual assessment, which provides a more tailored evaluation by including cognitive decisions regarding an adolescent's sexual actions.

  17. Impact of age on the importance of systolic and diastolic blood pressures for stroke risk: the MOnica, Risk, Genetics, Archiving, and Monograph (MORGAM) Project.

    PubMed

    Vishram, Julie K K; Borglykke, Anders; Andreasen, Anne H; Jeppesen, Jørgen; Ibsen, Hans; Jørgensen, Torben; Broda, Grazyna; Palmieri, Luigi; Giampaoli, Simona; Donfrancesco, Chiara; Kee, Frank; Mancia, Giuseppe; Cesana, Giancarlo; Kuulasmaa, Kari; Sans, Susana; Olsen, Michael H

    2012-11-01

    This study investigates age-related shifts in the relative importance of systolic (SBP) and diastolic (DBP) blood pressures as predictors of stroke and whether these relations are influenced by other cardiovascular risk factors. Using 34 European cohorts from the MOnica, Risk, Genetics, Archiving, and Monograph (MORGAM) Project with baseline between 1982 and 1997, 68 551 subjects aged 19 to 78 years, without cardiovascular disease and not receiving antihypertensive treatment, were included. During a mean of 13.2 years of follow-up, stroke incidence was 2.8%. Stroke risk was analyzed using hazard ratios per 10-mm Hg/5-mm Hg increase in SBP/DBP by multivariate-adjusted Cox regressions, including SBP and DBP simultaneously. Because of nonlinearity, DBP was analyzed separately for DBP ≥ 71 mm Hg and DBP <71 mm Hg. Stroke risk was associated positively with SBP and DBP ≥ 71 mm Hg (SBP/DBP ≥ 71 mm Hg; hazard ratios: 1.15/1.06 [95% CI: 1.12-1.18/1.03-1.09]) and negatively with DBP <71 mm Hg (0.88[0.79-0.98]). The hazard ratio for DBP decreased with age (P<0.001) and was not influenced by other cardiovascular risk factors. Taking into account the age × DBP interaction, both SBP and DBP ≥ 71 mm Hg were significantly associated with stroke risk until age 62 years, but in subjects older than 46 years the superiority of SBP for stroke risk exceeded that of DBP ≥ 71 mm Hg and remained significant until age 78 years. DBP <71 mm Hg became significant at age 50 years with an inverse relation to stroke risk. In Europeans, stroke risk should be assessed by both SBP and DBP until age 62 years with increased focus on SBP from age 47 years. From age 62 years, emphasis should be on SBP without neglecting the potential harm of very low DBP.

  18. Technique for the integral casting of pressure instrumentation in wind-tunnel models

    NASA Technical Reports Server (NTRS)

    Jackson, C. M., Jr.; Summerfield, D. G.

    1971-01-01

    Wind tunnel models are cast around core consisting of array of tubing. Principal advantage of technique is that greater number of pressure orifices are easily installed, without compromising aerodynamic shape of model. Technique reduces construction cost by about 50 percent.

  19. Modeling Commercial Turbofan Engine Icing Risk With Ice Crystal Ingestion

    NASA Technical Reports Server (NTRS)

    Jorgenson, Philip C. E.; Veres, Joseph P.

    2013-01-01

    The occurrence of ice accretion within commercial high bypass aircraft turbine engines has been reported under certain atmospheric conditions. Engine anomalies have taken place at high altitudes that have been attributed to ice crystal ingestion, partially melting, and ice accretion on the compression system components. The result was degraded engine performance, and one or more of the following: loss of thrust control (roll back), compressor surge or stall, and flameout of the combustor. As ice crystals are ingested into the fan and low pressure compression system, the increase in air temperature causes a portion of the ice crystals to melt. It is hypothesized that this allows the ice-water mixture to cover the metal surfaces of the compressor stationary components which leads to ice accretion through evaporative cooling. Ice accretion causes a blockage which subsequently results in the deterioration in performance of the compressor and engine. The focus of this research is to apply an engine icing computational tool to simulate the flow through a turbofan engine and assess the risk of ice accretion. The tool is comprised of an engine system thermodynamic cycle code, a compressor flow analysis code, and an ice particle melt code that has the capability of determining the rate of sublimation, melting, and evaporation through the compressor flow path, without modeling the actual ice accretion. A commercial turbofan engine which has previously experienced icing events during operation in a high altitude ice crystal environment has been tested in the Propulsion Systems Laboratory (PSL) altitude test facility at NASA Glenn Research Center. The PSL has the capability to produce a continuous ice cloud which are ingested by the engine during operation over a range of altitude conditions. The PSL test results confirmed that there was ice accretion in the engine due to ice crystal ingestion, at the same simulated altitude operating conditions as experienced previously in

  20. Pore water pressure variations in Subpermafrost groundwater : Numerical modeling compared with experimental modeling

    NASA Astrophysics Data System (ADS)

    Rivière, Agnès.; Goncalves, Julio; Jost, Anne; Font, Marianne

    2010-05-01

    Development and degradation of permafrost directly affect numerous hydrogeological processes such as thermal regime, exchange between river and groundwater, groundwater flows patterns and groundwater recharge (Michel, 1994). Groundwater in permafrost area is subdivided into two zones: suprapermafrost and subpermafrost which are separated by permafrost. As a result of the volumetric expansion of water upon freezing and assuming ice lenses and frost heave do not form freezing in a saturated aquifer, the progressive formation of permafrost leads to the pressurization of the subpermafrost groundwater (Wang, 2006). Therefore disappearance or aggradation of permafrost modifies the confined or unconfined state of subpermafrost groundwater. Our study focuses on modifications of pore water pressure of subpermafrost groundwater which could appear during thawing and freezing of soil. Numerical simulation allows elucidation of some of these processes. Our numerical model accounts for phase changes for coupled heat transport and variably saturated flow involving cycles of freezing and thawing. The flow model is a combination of a one-dimensional channel flow model which uses Manning-Strickler equation and a two-dimensional vertically groundwater flow model using Richards equation. Numerical simulation of heat transport consisted in a two dimensional model accounting for the effects of latent heat of phase change of water associated with melting/freezing cycles which incorporated the advection-diffusion equation describing heat-transfer in porous media. The change of hydraulic conductivity and thermal conductivity are considered by our numerical model. The model was evaluated by comparing predictions with data from laboratory freezing experiments. Experimental design was undertaken at the Laboratory M2C (Univesité de Caen-Basse Normandie, CNRS, France). The device consisted of a Plexiglas box insulated on all sides except on the top. Precipitation and ambient temperature are

  1. Composite Pressure Vessel Variability in Geometry and Filament Winding Model

    NASA Technical Reports Server (NTRS)

    Green, Steven J.; Greene, Nathanael J.

    2012-01-01

    Composite pressure vessels (CPVs) are used in a variety of applications ranging from carbon dioxide canisters for paintball guns to life support and pressurant storage on the International Space Station. With widespread use, it is important to be able to evaluate the effect of variability on structural performance. Data analysis was completed on CPVs to determine the amount of variation that occurs among the same type of CPV, and a filament winding routine was developed to facilitate study of the effect of manufacturing variation on structural response.

  2. Back-end Science Model Integration for Ecological Risk Assessment

    EPA Science Inventory

    The U.S. Environmental Protection Agency (USEPA) relies on a number of ecological risk assessment models that have been developed over 30-plus years of regulating pesticide exposure and risks under Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) and the Endangered Spe...

  3. Back-end Science Model Integration for Ecological Risk Assessment.

    EPA Science Inventory

    The U.S. Environmental Protection Agency (USEPA) relies on a number of ecological risk assessment models that have been developed over 30-plus years of regulating pesticide exposure and risks under Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) and the Endangered Spe...

  4. Risk Prediction Models for Other Cancers or Multiple Sites

    Cancer.gov

    Developing statistical models that estimate the probability of developing other multiple cancers over a defined period of time will help clinicians identify individuals at higher risk of specific cancers, allowing for earlier or more frequent screening and counseling of behavioral changes to decrease risk.

  5. Pressurization System Modeling for a Generic Bimese Two- Stage-to-Orbit Reusable Launch Vehicle

    NASA Technical Reports Server (NTRS)

    Mazurkivich, Pete; Chandler, Frank; Nguyen, Han

    2005-01-01

    A pressurization system model was developed for a generic bimese Two-Stage-to-orbit Reusable Launch Vehicle using a cross-feed system and operating with densified propellants. The model was based on the pressurization system model for a crossfeed subscale water test article and was validated with test data obtained from the test article. The model consists of the liquid oxygen and liquid hydrogen pressurization models, each made up of two submodels, Booster and Orbiter tank pressurization models. The tanks are controlled within a 0.2-psi band and pressurized on the ground with ambient helium and autogenously in flight with gaseous oxygen and gaseous hydrogen. A 15-psi pressure difference is maintained between the Booster and Orbiter tanks to ensure crossfeed check valve closure before Booster separation. The analysis uses an ascent trajectory generated for a generic bimese vehicle and a tank configuration based on the Space Shuttle External Tank. It determines the flow rates required to pressurize the tanks on the ground and in flight, and demonstrates the model's capability to analyze the pressurization system performance of a full-scale bimese vehicle with densified propellants.

  6. Computational modeling of the pressurization process in a NASP vehicle propellant tank experimental simulation

    NASA Technical Reports Server (NTRS)

    Sasmal, G. P.; Hochstein, J. I.; Wendl, M. C.; Hardy, T. L.

    1991-01-01

    A multidimensional computational model of the pressurization process in a slush hydrogen propellant storage tank was developed and its accuracy evaluated by comparison to experimental data measured for a 5 ft diameter spherical tank. The fluid mechanic, thermodynamic, and heat transfer processes within the ullage are represented by a finite-volume model. The model was shown to be in reasonable agreement with the experiment data. A parameter study was undertaken to examine the dependence of the pressurization process on initial ullage temperature distribution and pressurant mass flow rate. It is shown that for a given heat flux rate at the ullage boundary, the pressurization process is nearly independent of initial temperature distribution. Significant differences were identified between the ullage temperature and velocity fields predicted for pressurization of slush and those predicted for pressurization of liquid hydrogen. A simplified model of the pressurization process was constructed in search of a dimensionless characterization of the pressurization process. It is shown that the relationship derived from this simplified model collapses all of the pressure history data generated during this study into a single curve.

  7. Modified pressure loss model for T-junctions of engine exhaust manifold

    NASA Astrophysics Data System (ADS)

    Wang, Wenhui; Lu, Xiaolu; Cui, Yi; Deng, Kangyao

    2014-11-01

    The T-junction model of engine exhaust manifolds significantly influences the simulation precision of the pressure wave and mass flow rate in the intake and exhaust manifolds of diesel engines. Current studies have focused on constant pressure models, constant static pressure models and pressure loss models. However, low model precision is a common disadvantage when simulating engine exhaust manifolds, particularly for turbocharged systems. To study the performance of junction flow, a cold wind tunnel experiment with high velocities at the junction of a diesel exhaust manifold is performed, and the variation in the pressure loss in the T-junction under different flow conditions is obtained. Despite the trend of the calculated total pressure loss coefficient, which is obtained by using the original pressure loss model and is the same as that obtained from the experimental results, large differences exist between the calculated and experimental values. Furthermore, the deviation becomes larger as the flow velocity increases. By improving the Vazsonyi formula considering the flow velocity and introducing the distribution function, a modified pressure loss model is established, which is suitable for a higher velocity range. Then, the new model is adopted to solve one-dimensional, unsteady flow in a D6114 turbocharged diesel engine. The calculated values are compared with the measured data, and the result shows that the simulation accuracy of the pressure wave before the turbine is improved by 4.3% with the modified pressure loss model because gas compressibility is considered when the flow velocities are high. The research results provide valuable information for further junction flow research, particularly the correction of the boundary condition in one-dimensional simulation models.

  8. Lymphatic Filariasis Transmission Risk Map of India, Based on a Geo-Environmental Risk Model

    PubMed Central

    Sabesan, Shanmugavelu; Raju, Konuganti Hari Kishan; Srivastava, Pradeep Kumar; Jambulingam, Purushothaman

    2013-01-01

    Abstract The strategy adopted by a global program to interrupt transmission of lymphatic filariasis (LF) is mass drug administration (MDA) using chemotherapy. India also followed this strategy by introducing MDA in the historically known endemic areas. All other areas, which remained unsurveyed, were presumed to be nonendemic and left without any intervention. Therefore, identification of LF transmission risk areas in the entire country has become essential so that they can be targeted for intervention. A geo-environmental risk model (GERM) developed earlier was used to create a filariasis transmission risk map for India. In this model, a Standardized Filariasis Transmission Risk Index (SFTRI, based on geo-environmental risk variables) was used as a predictor of transmission risk. The relationship between SFTRI and endemicity (historically known) of an area was quantified by logistic regression analysis. The quantified relationship was validated by assessing the filarial antigenemia status of children living in the unsurveyed areas through a ground truth study. A significant positive relationship was observed between SFTRI and the endemicity of an area. Overall, the model prediction of filarial endemic status of districts was found to be correct in 92.8% of the total observations. Thus, among the 190 districts hitherto unsurveyed, as many as 113 districts were predicted to be at risk, and the remaining at no risk. The GERM developed on geographic information system (GIS) platform is useful for LF spatial delimitation on a macrogeographic/regional scale. Furthermore, the risk map developed will be useful for the national LF elimination program by identifying areas at risk for intervention and for undertaking surveillance in no-risk areas. PMID:23808973

  9. Applying risk assessment models in non-surgical patients: effective risk stratification.

    PubMed

    Eldor, A

    1999-08-01

    Pulmonary embolism and deep vein thrombosis are serious complications of non-surgical patients, but scarcity of data documenting prophylaxis means antithrombotic therapy is rarely used. Prediction of risk is complicated by the variation in the medical conditions associated with venous thromboembolism (VTE), and lack of data defining risk in different groups. Accurate risk assessment is further confounded by inherited or acquired factors for VTE, additional risk due to medical interventions, and interactions between risk factors. Acquired and inherited risk factors may underlie thromboembolic complications in a range of conditions, including pregnancy, ischaemic stroke, myocardial infarction and cancer. Risk stratification may be feasible in non-surgical patients by considering individual risk factors and their cumulative effects. Current risk assessment models require expansion and modification to reflect emerging evidence in the non-surgical field. A large on-going study of prophylaxis with low-molecular-weight heparin in non-surgical patients will clarify our understanding of the components of risk, and assist in developing therapy recommendations.

  10. Genome-wide linkage analysis of the tracking of systolic blood pressure using a mixed model

    PubMed Central

    Wang, Tao; Zhu, Guohua; Keen, Kevin J

    2003-01-01

    Background Elevated blood pressure in middle age is a major risk factor for subsequent cardiovascular complications. An important longitudinal characteristic of blood pressure is the "tracking phenomenon". Tracking is defined as the persistence of the rank of a person's blood pressure level in a group over a long period of time. In this analysis, we used the Framingham data to investigate whether there are some genes responsible for this phenomenon. Results Both two-point and multipoint linkage analyses were applied to family members with complete data only and to all family data with missing values imputed by a Gaussian model. The results of two-point linkage analysis indicated that two loci for linkage with the intercept were on chromosomes 10 and 13, and two loci for linkage with both slope and intercept were on chromosomes 1 and 3. Multipoint linkage analysis indicated only one region, 200–240 cM on chromosome 1, to be linked with both intercept and slope. For the intercept of SBP, the highest LOD (4.43) was found at 214 cM when missing data were imputed, and the highest LOD (2.81) was at 231 cM for the complete case data. For the slope of SBP, the highest multipoint LODs were 3.63 at 227 cM and 2.02 at 234 cM for the complete case data and imputation data, respectively. Conclusion One or more genes in the range of 200–240 cM on chromosome 1 may be related to the tracking phenomenon of SBP. PMID:14975156

  11. Model-Based, Noninvasive Monitoring of Intracranial Pressure

    DTIC Science & Technology

    2012-10-01

    nICP) estimate requires simultaneous measurement of the waveforms of arterial blood pressure ( ABP ), obtained via radial artery catheter or finger...initial database comprises subarachnoid hemorrhage patients in neuro-intensive care at our partner hospital, for whom ICP, ABP and CBFV are currently

  12. Submission Form for Peer-Reviewed Cancer Risk Prediction Models

    Cancer.gov

    If you have information about a peer-reviewd cancer risk prediction model that you would like to be considered for inclusion on this list, submit as much information as possible through the form on this page.

  13. On testing models for the pressure-strain correlation of turbulence using direct simulations

    NASA Technical Reports Server (NTRS)

    Speziale, Charles G.; Gatski, Thomas B.; Sarkar, Sutanu

    1992-01-01

    Direct simulations of homogeneous turbulence have, in recent years, come into widespread use for the evaluation of models for the pressure-strain correlation of turbulence. While work in this area has been beneficial, the increasingly common practice of testing the slow and rapid parts of these models separately in uniformly strained turbulent flows is shown in this paper to be unsound. For such flows, the decomposition of models for the total pressure-strain correlation into slow and rapid parts is ambiguous. Consequently, when tested in this manner, misleading conclusions can be drawn about the performance of pressure-strain models. This point is amplified by illustrative calculations of homogeneous shear flow where other pitfalls in the evaluation of models are also uncovered. More meaningful measures for testing the performance of pressure-strain models in uniformly strained turbulent flows are proposed and the implications for turbulence modeling are discussed.

  14. Modeling Exposure to Persistent Chemicals in Hazard and Risk Assessment

    SciTech Connect

    Cowan-Ellsberry, Christina E.; McLachlan, Michael S.; Arnot, Jon A.; MacLeod, Matthew; McKone, Thomas E.; Wania, Frank

    2008-11-01

    Fate and exposure modeling has not thus far been explicitly used in the risk profile documents prepared to evaluate significant adverse effect of candidate chemicals for either the Stockholm Convention or the Convention on Long-Range Transboundary Air Pollution. However, we believe models have considerable potential to improve the risk profiles. Fate and exposure models are already used routinely in other similar regulatory applications to inform decisions, and they have been instrumental in building our current understanding of the fate of POP and PBT chemicals in the environment. The goal of this paper is to motivate the use of fate and exposure models in preparing risk profiles in the POP assessment procedure by providing strategies for incorporating and using models. The ways that fate and exposure models can be used to improve and inform the development of risk profiles include: (1) Benchmarking the ratio of exposure and emissions of candidate chemicals to the same ratio for known POPs, thereby opening the possibility of combining this ratio with the relative emissions and relative toxicity to arrive at a measure of relative risk. (2) Directly estimating the exposure of the environment, biota and humans to provide information to complement measurements, or where measurements are not available or are limited. (3) To identify the key processes and chemical and/or environmental parameters that determine the exposure; thereby allowing the effective prioritization of research or measurements to improve the risk profile. (4) Predicting future time trends including how quickly exposure levels in remote areas would respond to reductions in emissions. Currently there is no standardized consensus model for use in the risk profile context. Therefore, to choose the appropriate model the risk profile developer must evaluate how appropriate an existing model is for a specific setting and whether the assumptions and input data are relevant in the context of the application

  15. A Hybrid Tsunami Risk Model for Japan

    NASA Astrophysics Data System (ADS)

    Haseemkunju, A. V.; Smith, D. F.; Khater, M.; Khemici, O.; Betov, B.; Scott, J.

    2014-12-01

    Around the margins of the Pacific Ocean, denser oceanic plates slipping under continental plates cause subduction earthquakes generating large tsunami waves. The subducting Pacific and Philippine Sea plates create damaging interplate earthquakes followed by huge tsunami waves. It was a rupture of the Japan Trench subduction zone (JTSZ) and the resultant M9.0 Tohoku-Oki earthquake that caused the unprecedented tsunami along the Pacific coast of Japan on March 11, 2011. EQECAT's Japan Earthquake model is a fully probabilistic model which includes a seismo-tectonic model describing the geometries, magnitudes, and frequencies of all potential earthquake events; a ground motion model; and a tsunami model. Within the much larger set of all modeled earthquake events, fault rupture parameters for about 24000 stochastic and 25 historical tsunamigenic earthquake events are defined to simulate tsunami footprints using the numerical tsunami model COMCOT. A hybrid approach using COMCOT simulated tsunami waves is used to generate inundation footprints, including the impact of tides and flood defenses. Modeled tsunami waves of major historical events are validated against observed data. Modeled tsunami flood depths on 30 m grids together with tsunami vulnerability and financial models are then used to estimate insured loss in Japan from the 2011 tsunami. The primary direct report of damage from the 2011 tsunami is in terms of the number of buildings damaged by municipality in the tsunami affected area. Modeled loss in Japan from the 2011 tsunami is proportional to the number of buildings damaged. A 1000-year return period map of tsunami waves shows high hazard along the west coast of southern Honshu, on the Pacific coast of Shikoku, and on the east coast of Kyushu, primarily associated with major earthquake events on the Nankai Trough subduction zone (NTSZ). The highest tsunami hazard of more than 20m is seen on the Sanriku coast in northern Honshu, associated with the JTSZ.

  16. Pressure fluctuation prediction of a model pump turbine at no load opening by a nonlinear k-ε turbulence model

    NASA Astrophysics Data System (ADS)

    Liu, J. T.; Zuo, Z. G.; Liu, S. H.; Wu, Y. L.

    2014-03-01

    In this paper, a new nonlinear k-ε turbulence model based on RNG k-ε turbulence model and Wilcox's k-ω turbulence model was proposed to simulate the unsteady flow and to predict the pressure fluctuation through a model pump turbine for engineering application. Calculations on a curved rectangular duct proved that the nonlinear k-ε turbulence model is applicable for high pressure gradient flows and large curvature flows. The numerically predicted relative pressure amplitude (peak to peak) in time domain to the pump turbine head at no load condition is very close to the experimental data. It is indicated that the prediction of the pressure fluctuation is valid by the present nonlinear k-ε method. The high pressure fluctuation in this area is the main issue for pump turbine design, especially at high head condition.

  17. Neuronal changes after chronic high blood pressure in animal models and its implication for vascular dementia.

    PubMed

    Flores, Gonzalo; Flores-Gómez, Gabriel D; de Jesús Gomez-Villalobos, Ma

    2016-05-01

    Vascular dementia is a devastating disorder not only for the patient, but also for the family because this neurocognitive disorder breaks the patient's independence, and leads to family care of the patient with a high cost for the family. This complex disorder alters memory, learning, judgment, emotional control and social behavior and affects 4% of the elderly world population. The high blood pressure or arterial hypertension is a major risk factor for cerebrovascular disease, which in most cases leads to vascular dementia. Interestingly, this neurocognitive disorder starts after long lasting hypertension, which is associated with reduced cerebral blood flow or hypoperfusion, and complete or incomplete ischemia with cortical thickness. Animal models have been generated to elucidate the pathophysiology of this disorder. It is known that dendritic complexity determines the receptive synaptic contacts, and the loss of dendritic spine and arbor stability are strongly associated with dementia in humans. This review evaluates relevant data of human and animal models that have investigated the link between long-lasting arterial hypertension and neural morphological changes in the context of vascular dementia. We examined the effect of chronic arterial hypertension and aged in vascular dementia. Neural dendritic morphology in the prefrontal cortex and the dorsal hippocampus and nucleus accumbens after chronic hypertension was diskussed in the animal models of hypertension. Chronic hypertension reduced the dendritic length and spine density in aged rats.

  18. Numerical Modeling and Test Data Comparison of Propulsion Test Article Helium Pressurization System

    NASA Technical Reports Server (NTRS)

    Holt, Kimberly; Majumdar, Alok; Steadman, Todd; Hedayat, Ali; Fogle, Frank R. (Technical Monitor)

    2000-01-01

    A transient model of the propulsion test article (PTA) helium pressurization system was developed using the generalized fluid system simulation program (GFSSP). The model included pressurization lines from the facility interface to the engine purge interface and liquid oxygen (lox) and rocket propellant-1 (RP-1) tanks, the propellant tanks themselves including ullage space, and propellant feed lines to their respective pump interfaces. GFSSP's capability was extended to model a control valve to maintain ullage pressure within a specified limit and pressurization processes such as heat transfer between ullage gas, propellant, and the tank wall as well as conduction in the tank wall. The purpose of the model is to predict the flow system characteristics in the entire pressurization system during 80 sec of lower feed system priming, 420 sec of fuel and lox pump priming, and 150 sec of engine firing.

  19. Usefulness and limitations of global flood risk models

    NASA Astrophysics Data System (ADS)

    Ward, Philip; Jongman, Brenden; Salamon, Peter; Simpson, Alanna; Bates, Paul; De Groeve, Tom; Muis, Sanne; Coughlan de Perez, Erin; Rudari, Roberto; Mark, Trigg; Winsemius, Hessel

    2016-04-01

    Global flood risk models are now a reality. Initially, their development was driven by a demand from users for first-order global assessments to identify risk hotspots. Relentless upward trends in flood damage over the last decade have enhanced interest in such assessments. The adoption of the Sendai Framework for Disaster Risk Reduction and the Warsaw International Mechanism for Loss and Damage Associated with Climate Change Impacts have made these efforts even more essential. As a result, global flood risk models are being used more and more in practice, by an increasingly large number of practitioners and decision-makers. However, they clearly have their limits compared to local models. To address these issues, a team of scientists and practitioners recently came together at the Global Flood Partnership meeting to critically assess the question 'What can('t) we do with global flood risk models?'. The results of this dialogue (Ward et al., 2013) will be presented, opening a discussion on similar broader initiatives at the science-policy interface in other natural hazards. In this contribution, examples are provided of successful applications of global flood risk models in practice (for example together with the World Bank, Red Cross, and UNISDR), and limitations and gaps between user 'wish-lists' and model capabilities are discussed. Finally, a research agenda is presented for addressing these limitations and reducing the gaps. Ward et al., 2015. Nature Climate Change, doi:10.1038/nclimate2742

  20. Differential effects of the changes of LDL cholesterol and systolic blood pressure on the risk of carotid artery atherosclerosis

    PubMed Central

    2012-01-01

    Background The effects of baseline and changes in blood pressure and low density lipoprotein (LDL) cholesterol on the carotid intima media thickness (IMT) have not been well documented. Methods A total of 2572 adults (mean age 53.8 years, 54.6% women) in a Taiwanese community undertook three blood pressure and LDL cholesterol examinations over 6 years. Latent growth curve modeling was used to investigate the effects of baseline and change in blood pressure and LDL cholesterol on IMT. Results Greater baseline LDL and blood pressure were associated with an increase in IMT (0.005 ± 0.002 mm per 1 mg/dL [p = 0.006] and 0.041 ± 0.004 mm mmHg [p <0.0001], respectively. Change in blood pressure was associated with a significant increase in IMT (0.047±0.016, P = 0.004), whilst the association between change in LDL and change in IMT was not statistically significant (0.008±0.006, P = 0.20). Conclusions Carotid IMT was associated with baseline blood pressure and LDL cholesterol, yet only changes of blood pressure, not LDL cholesterol, were related to carotid IMT during the 6-year observation. PMID:22900906

  1. Sensitivity and uncertainty analysis of a regulatory risk model

    SciTech Connect

    Kumar, A.; Manocha, A.; Shenoy, T.

    1999-07-01

    Health Risk Assessments (H.R.A.s) are increasingly being used in the environmental decision making process, starting from problem identification to the final clean up activities. A key issue concerning the results of these risk assessments is the uncertainty associated with them. This uncertainty has been associated with highly conservative estimates of risk assessment parameters in past studies. The primary purpose of this study was to investigate error propagation through a risk model. A hypothetical glass plant situated in the state of California was studied. Air emissions from this plant were modeled using the ISCST2 model and the risk was calculated using the ACE2588 model. The downwash was also considered during the concentration calculations. A sensitivity analysis on the risk computations identified five parameters--mixing depth for human consumption, deposition velocity, weathering constant, interception factors for vine crop and the average leaf vegetable consumption--which had the greatest impact on the calculated risk. A Monte Carlo analysis using these five parameters resulted in a distribution with a lesser percentage deviation than the percentage standard deviation of the input parameters.

  2. Proactive multifactorial intervention strategy reduces the risk of cardiovascular disease estimated with region-specific risk assessment models in Pacific Asian patients participating in the CRUCIAL trial.

    PubMed

    Cho, Eun Joo; Kim, Jae Hyung; Sutradhar, Santosh; Yunis, Carla; Westergaard, Mogens

    2013-12-01

    Despite race, ethnic, and regional differences in cardiovascular disease risk, many worldwide hypertension management guidelines recommend the use of the Framingham coronary heart disease (CHD) risk equation to guide treatment decisions. This subanalysis of the recently published CRUCIAL trial compared the treatment-related reductions in calculated CHD and stroke risk among Pacific Asian (PA) patients using a variety of region-specific risk assessment models. As a result, greater reductions in systolic and diastolic blood pressure, low-density lipoprotein cholesterol, and triglycerides were observed in the proactive multifactorial intervention (PMI) arm compared with the usual care arm at Week 52 for PA patients. The relative percentage change in 10-yr CHD risk between baseline and Week 52 in the PMI versus usual care arms was greatest using the NIPPON DATA80 fatal CHD model (LS [least square] mean difference -42.6%), and similar in the SCORE fatal CHD and Framingham total CHD models (LS mean difference -29.4% and -30.8%, respectively). The single-pill based PMI approach is consistently effective in reducing cardiovascular disease risk, evaluated using a variety of risk assessment models. (ClinicalTrials.gov registration number: NCT00407537).

  3. Proactive Multifactorial Intervention Strategy Reduces the Risk of Cardiovascular Disease Estimated with Region-Specific Risk Assessment Models in Pacific Asian Patients Participating in the CRUCIAL Trial

    PubMed Central

    Cho, Eun Joo; Sutradhar, Santosh; Yunis, Carla; Westergaard, Mogens

    2013-01-01

    Despite race, ethnic, and regional differences in cardiovascular disease risk, many worldwide hypertension management guidelines recommend the use of the Framingham coronary heart disease (CHD) risk equation to guide treatment decisions. This subanalysis of the recently published CRUCIAL trial compared the treatment-related reductions in calculated CHD and stroke risk among Pacific Asian (PA) patients using a variety of region-specific risk assessment models. As a result, greater reductions in systolic and diastolic blood pressure, low-density lipoprotein cholesterol, and triglycerides were observed in the proactive multifactorial intervention (PMI) arm compared with the usual care arm at Week 52 for PA patients. The relative percentage change in 10-yr CHD risk between baseline and Week 52 in the PMI versus usual care arms was greatest using the NIPPON DATA80 fatal CHD model (LS [least square] mean difference -42.6%), and similar in the SCORE fatal CHD and Framingham total CHD models (LS mean difference -29.4% and -30.8%, respectively). The single-pill based PMI approach is consistently effective in reducing cardiovascular disease risk, evaluated using a variety of risk assessment models. (ClinicalTrials.gov registration number: NCT00407537) PMID:24339703

  4. Pressure Modeling of Char-Forming and Laminated Materials.

    DTIC Science & Technology

    1983-06-01

    terms of rate of total mass loss, flame heighit, upward flame spread rate, and maximum lateral flame dimensions during the spread process . The cnar...flame extent during the spread process . The char-forming materials (pine-wood, particle-board and a rigid, polyurethane foam) are tested in a 900... processes occur. 2. The behavior of the flame spread process at elevated air pressures, for walls composed of a face layer of PMMA with a thick

  5. Discussing Coronary Risk with Patients to Improve Blood Pressure Treatment: Secondary Results from the CHECK-UP Study

    PubMed Central

    Lowensteyn, Ilka; Joseph, Lawrence; Kaouache, Mohammed; Marchand, Sylvie; Coupal, Louis; Boudreau, Ghislain

    2008-01-01

    Objectives Hypertension is common among patients with dyslipidemia but is often poorly treated. The objective of this analysis was to evaluate how a decision aid, used by primary care physicians to improve lipid therapy, impacted on the treatment of hypertension. Study Design Data were analyzed from patients enrolled in a randomized trial focusing primarily on the treatment of dyslipidemia. Patients received usual care or a coronary risk profile every three months to monitor the risk reduction following lifestyle changes and/or pharmacotherapy to treat dyslipidemia. Hypertension management was assessed based on a post hoc analysis of individuals whose blood pressure exceeded current national hypertension guidelines. Results There were 2,631 subjects who completed the study. Among 1,352 patients without diagnosed hypertension, 30% were above target on at least three consecutive visits. Among 1,279 individuals with known hypertension, 69% were above target on at least two consecutive visits. Overall, patients receiving risk profiles were more likely to receive appropriate antihypertensive therapy (OR = 1.40, 95% CI 1.11 – 1.78) compared to those receiving usual care. After adjustment for inter-physician variability and potential confounders, the use of the risk profile was associated with an increased likelihood of starting therapy (OR = 1.78, 95% CI 1.06 – 3.00) or modifying therapy (OR = 1.40, 95% CI 1.03 – 1.91). Conclusions In this clinical trial of dyslipidemia management, inadequately controlled hypertension was common, occurring in nearly 50% of individuals. Ongoing coronary risk assessment was associated with more appropriate blood pressure management. Cardiovascular risk assessment decision aids should be further evaluated in a randomized trial of hypertension therapy. PMID:18937013

  6. Persistence Characteristics of Wind-Tunnel Pressure Signatures From Two Similar Models

    NASA Technical Reports Server (NTRS)

    Mack, Robert J.

    2004-01-01

    Pressure signatures generated by two sonic-boom wind-tunnel models and measured at Mach 2 are presented, analyzed, and discussed. The two wind-tunnel models differed in length and span by a factor of fourteen, but were similar in wing-body planform shape. The geometry of the larger model had been low-boom tailored to generate a flat top ground pressure signature, and the nacelles-off pressure signatures from this model became more flattop in shape as the model-probe separation distances increased from 0.94 to 4.4 span lengths. The geometry of the smaller model had not been low-boom tailored, yet its measured pressure signatures had non-N-wave shapes that persisted as model-probe separation distances increased from 26.0 to 104.2 span lengths. Since the overall planforms of the two wind-tunnel models were so similar, it was concluded that the shape-persistence trends in the pressure signatures of the smaller, non-low-boom tailored model would also be present at very large distances in the pressure signatures of the larger, low-boom-tailored model.

  7. Dietary Information Improves Model Performance and Predictive Ability of a Noninvasive Type 2 Diabetes Risk Model

    PubMed Central

    Han, Tianshu; Tian, Shuang; Wang, Li; Liang, Xi; Cui, Hongli; Du, Shanshan; Na, Guanqiong; Na, Lixin; Sun, Changhao

    2016-01-01

    There is no diabetes risk model that includes dietary predictors in Asia. We sought to develop a diet-containing noninvasive diabetes risk model in Northern China and to evaluate whether dietary predictors can improve model performance and predictive ability. Cross-sectional data for 9,734 adults aged 20–74 years old were used as the derivation data, and results obtained for a cohort of 4,515 adults with 4.2 years of follow-up were used as the validation data. We used a logistic regression model to develop a diet-containing noninvasive risk model. Akaike’s information criterion (AIC), area under curve (AUC), integrated discrimination improvements (IDI), net classification improvement (NRI) and calibration statistics were calculated to explicitly assess the effect of dietary predictors on a diabetes risk model. A diet-containing type 2 diabetes risk model was developed. The significant dietary predictors including the consumption of staple foods, livestock, eggs, potato, dairy products, fresh fruit and vegetables were included in the risk model. Dietary predictors improved the noninvasive diabetes risk model with a significant increase in the AUC (delta AUC = 0.03, P<0.001), an increase in relative IDI (24.6%, P-value for IDI <0.001), an increase in NRI (category-free NRI = 0.155, P<0.001), an increase in sensitivity of the model with 7.3% and a decrease in AIC (delta AIC = 199.5). The results of the validation data were similar to the derivation data. The calibration of the diet-containing diabetes risk model was better than that of the risk model without dietary predictors in the validation data. Dietary information improves model performance and predictive ability of noninvasive type 2 diabetes risk model based on classic risk factors. Dietary information may be useful for developing a noninvasive diabetes risk model. PMID:27851788

  8. Intraocular pressure and glaucoma: Is physical exercise beneficial or a risk?

    PubMed

    McMonnies, Charles William

    2016-01-01

    Intraocular pressure may become elevated with muscle exertion, changes in body position and increased respiratory volumes, especially when Valsalva manoeuver mechanisms are involved. All of these factors may be present during physical exercise, especially if hydration levels are increased. This review examines the evidence for intraocular pressure changes during and after physical exercise. Intraocular pressure elevation may result in a reduction in ocular perfusion pressure with the associated possibility of mechanical and/or ischaemic damage to the optic nerve head. A key consideration is the possibility that, rather than being beneficial for patients who are susceptible to glaucomatous pathology, any intraocular pressure elevation could be detrimental. Lower intraocular pressure after exercise may result from its elevation causing accelerated aqueous outflow during exercise. Also examined is the possibility that people who have lower frailty are more likely to exercise as well as less likely to have or develop glaucoma. Consequently, lower prevalence of glaucoma would be expected among people who exercise. The evidence base for this topic is deficient and would be greatly improved by the availability of tonometry assessment during dynamic exercise, more studies which control for hydration levels, and methods for assessing the potential general health benefits of exercise against any possibility of exacerbated glaucomatous pathology for individual patients who are susceptible to such changes.

  9. A turbulent burst model for boundary layer flows with pressure gradient

    NASA Astrophysics Data System (ADS)

    Thomas, L. C.; Benton, D. J.

    The object of this paper is to develop a surface renewal model of the turbulent burst phenomenon for momentum and energy transfer in the wall region for turbulent boundary layer flows with pressure gradient. In addition to obtaining inner laws for the distributions in velocity and temperature, predictions are obtained for the effect of pressure gradient on the mean burst frequency and on the turbulent Prandtl number within the wall region for slight favorable and mild adverse pressure gradients.

  10. Building a Better Model: A Comprehensive Breast Cancer Risk Model Incorporating Breast Density to Stratify Risk and Apply Resources

    DTIC Science & Technology

    2012-10-01

    methods (CumulusV, Volpara), developed an automated area based 15. SUBJECT TERMS Breast cancer; risk model; mammography ; breast density 16...recommendations based on an individual’s risk beginning with personalized mammography screening decisions. This will be done by increasing the ability... mammography machine vendor. Once the model is complete, tested nationally, and proven accurate, it will be available for widespread use within five to six

  11. Evaluation of a computational model used to predict the patellofemoral contact pressure distribution.

    PubMed

    Elias, John J; Wilson, David R; Adamson, Robert; Cosgarea, Andrew J

    2004-03-01

    One possible cause of patellofemoral pain syndrome is excessive lateral force acting on the patella. Although several treatment methods focus on decreasing the lateral force acting on the patella, the relationship between the lateral force and the patellofemoral contact pressure distribution is unclear. A computational model has been developed to determine how loading variations alter the patellofemoral force and pressure distributions for individual knees. The model allows variation in the quadriceps and patella tendon forces, and calculates the predicted contact pressure distribution using the discrete element analysis technique. To characterize the accuracy of the model, four cadaver knees were flexed on a knee simulator with three initial Q-angles, while recording the force and pressure distributions with a pressure sensor. A model of each knee was created from CT data. Using the external force applied to the knee, the geometry of the knee, and the quadriceps origin as input, the pressure distribution was calculated during flexion. Similar trends were noted for the computational and experimental results. The percentage of the total force applied to the lateral cartilage increased with the Q-angle. The maximum contact pressure increased during flexion. The maximum lateral contact pressure increased with the Q-angle for three knees. For the other knee, increasing the Q-angle decreased the maximum lateral pressure. The maximum medial contact pressure decreased as the Q-angle increased. By characterizing the influence of patellofemoral loading on the force and pressure distributions, the computational model could be used to evaluate treatment methods prescribed for patellofemoral pain.

  12. Tea, but not coffee consumption, is associated with components of arterial pressure. The Observation of Cardiovascular Risk Factors study in Luxembourg.

    PubMed

    Alkerwi, Ala'a; Sauvageot, Nicolas; Crichton, Georgina E; Elias, Merrill F

    2015-07-01

    There is uncertainty regarding the impact of tea and coffee consumption on arterial blood pressure. The present study aimed to examine the association between blood pressure (BP) components, namely, systolic BP (SBP), diastolic BP, mean arterial pressure, and pulse pressure (PP), and tea or coffee consumption, taking into account simultaneous consumption. The study population was derived from a national cross-sectional stratified sample of 1352 individuals aged 18 to 69 years, recruited between November 2007 and January 2009 to participate in the Observation of Cardiovascular Risk Factors in Luxembourg study. We hypothesized that greater tea consumption would be independently associated with lower BP. Tea and coffee consumptions in deciliters per day were obtained from a semiquantitative food frequency questionnaire. Participants were classified into 3 groups: nonconsumers, ≤3-dL/d consumers, and >3-dL/d consumers of each beverage separately. After exclusion of subjects taking antihypertensive medications, several general linear models were performed to investigate the independent relationship between tea/coffee consumption and BP components. Tea consumers (36.3%) were more likely to be younger women, nonsmokers, with better cardiometabolic profiles, and less frequent chronic pathologies, whereas the reverse was true for coffee consumers (88%). Greater tea consumption was associated with lower SBP and PP values, after adjustment for age, sex, education, lifestyle, and dietary confounding factors, including coffee drinking. No association between BP components and coffee consumption was observed. Daily consumption of 1 dL of tea was associated with a significant reduction of SBP by 0.6 mm Hg and PP by 0.5 mm Hg. Given the widespread consumption of tea and coffee throughout the world, together with the major cardiovascular disease risk, our findings have important implications for human health.

  13. Quantitative assessment of changes in landslide risk using a regional scale run-out model

    NASA Astrophysics Data System (ADS)

    Hussin, Haydar; Chen, Lixia; Ciurean, Roxana; van Westen, Cees; Reichenbach, Paola; Sterlacchini, Simone

    2015-04-01

    The risk of landslide hazard continuously changes in time and space and is rarely a static or constant phenomena in an affected area. However one of the main challenges of quantitatively assessing changes in landslide risk is the availability of multi-temporal data for the different components of risk. Furthermore, a truly "quantitative" landslide risk analysis requires the modeling of the landslide intensity (e.g. flow depth, velocities or impact pressures) affecting the elements at risk. Such a quantitative approach is often lacking in medium to regional scale studies in the scientific literature or is left out altogether. In this research we modelled the temporal and spatial changes of debris flow risk in a narrow alpine valley in the North Eastern Italian Alps. The debris flow inventory from 1996 to 2011 and multi-temporal digital elevation models (DEMs) were used to assess the susceptibility of debris flow triggering areas and to simulate debris flow run-out using the Flow-R regional scale model. In order to determine debris flow intensities, we used a linear relationship that was found between back calibrated physically based Flo-2D simulations (local scale models of five debris flows from 2003) and the probability values of the Flow-R software. This gave us the possibility to assign flow depth to a total of 10 separate classes on a regional scale. Debris flow vulnerability curves from the literature and one curve specifically for our case study area were used to determine the damage for different material and building types associated with the elements at risk. The building values were obtained from the Italian Revenue Agency (Agenzia delle Entrate) and were classified per cadastral zone according to the Real Estate Observatory data (Osservatorio del Mercato Immobiliare, Agenzia Entrate - OMI). The minimum and maximum market value for each building was obtained by multiplying the corresponding land-use value (€/msq) with building area and number of floors

  14. The Global Earthquake Model and Disaster Risk Reduction

    NASA Astrophysics Data System (ADS)

    Smolka, A. J.

    2015-12-01

    Advanced, reliable and transparent tools and data to assess earthquake risk are inaccessible to most, especially in less developed regions of the world while few, if any, globally accepted standards currently allow a meaningful comparison of risk between places. The Global Earthquake Model (GEM) is a collaborative effort that aims to provide models, datasets and state-of-the-art tools for transparent assessment of earthquake hazard and risk. As part of this goal, GEM and its global network of collaborators have developed the OpenQuake engine (an open-source software for hazard and risk calculations), the OpenQuake platform (a web-based portal making GEM's resources and datasets freely available to all potential users), and a suite of tools to support modelers and other experts in the development of hazard, exposure and vulnerability models. These resources are being used extensively across the world in hazard and risk assessment, from individual practitioners to local and national institutions, and in regional projects to inform disaster risk reduction. Practical examples for how GEM is bridging the gap between science and disaster risk reduction are: - Several countries including Switzerland, Turkey, Italy, Ecuador, Papua-New Guinea and Taiwan (with more to follow) are computing national seismic hazard using the OpenQuake-engine. In some cases these results are used for the definition of actions in building codes. - Technical support, tools and data for the development of hazard, exposure, vulnerability and risk models for regional projects in South America and Sub-Saharan Africa. - Going beyond physical risk, GEM's scorecard approach evaluates local resilience by bringing together neighborhood/community leaders and the risk reduction community as a basis for designing risk reduction programs at various levels of geography. Actual case studies are Lalitpur in the Kathmandu Valley in Nepal and Quito/Ecuador. In agreement with GEM's collaborative approach, all

  15. Sleep Apnea Related Risk of Motor Vehicle Accidents is Reduced by Continuous Positive Airway Pressure: Swedish Traffic Accident Registry Data

    PubMed Central

    Karimi, Mahssa; Hedner, Jan; Häbel, Henrike; Nerman, Olle; Grote, Ludger

    2015-01-01

    Study Objectives: Obstructive sleep apnea (OSA) is associated with an increased risk of motor vehicle accidents (MVAs). The rate of MVAs in patients suspected of having OSA was determined and the effect of continuous positive airway pressure (CPAP) was investigated. Design: MVA rate in patients referred for OSA was compared to the rate in the general population using data from the Swedish Traffic Accident Registry (STRADA), stratified for age and calendar year. The risk factors for MVAs, using demographic and polygraphy data, and MVA rate before and after CPAP were evaluated in the patient group. Setting: Clinical sleep laboratory and population based control (n = 635,786). Patients: There were 1,478 patients, male sex 70.4%, mean age 53.6 (12.8) y. Interventions: CPAP. Measurements and Results: The number of accidents (n = 74) among patients was compared with the expected number (n = 30) from a control population (STRADA). An increased MVA risk ratio of 2.45 was found among patients compared with controls (P < 0.001). Estimated excess accident risk was most prominent in the elderly patients (65–80 y, seven versus two MVAs). In patients, driving distance (km/y), EDS (Epworth Sleepiness score ≥ 16), short habitual sleep time (≤ 5 h/night), and use of hypnotics were associated with increased MVA risk (odds ratios 1.2, 2.1, 2.7 and 2.1, all P ≤ 0.03). CPAP use ≥ 4 h/night was associated with a reduction of MVA incidence (7.6 to 2.5 accidents/1,000 drivers/y). Conclusions: The motor vehicle accident risk in this large cohort of unselected patients with obstructive sleep apnea suggests a need for accurate tools to identify individuals at risk. Sleep apnea severity (e.g., apnea-hypopnea index) failed to identify patients at risk. Citation: Karimi M, Hedner J, Häbel H, Nerman O, Grote L. Sleep apnea related risk of motor vehicle accidents is reduced by continuous positive airway pressure: Swedish traffic accident registry data. SLEEP 2015;38(3):341–349. PMID

  16. Modeling Manufacturing Processes to Mitigate Technological Risk

    SciTech Connect

    Allgood, G.O.; Manges, W.W.

    1999-10-24

    An economic model is a tool for determining the justifiable cost of new sensors and subsystems with respect to value and operation. This process balances the R and D costs against the expense of maintaining current operations and allows for a method to calculate economic indices of performance that can be used as control points in deciding whether to continue development or suspend actions. The model can also be used as an integral part of an overall control loop utilizing real-time process data from the sensor groups to make production decisions (stop production and repair machine, continue and warn of anticipated problems, queue for repairs, etc.). This model has been successfully used and deployed in the CAFE Project. The economic model was one of seven (see Fig. 1) elements critical in developing an investment strategy. It has been successfully used in guiding the R and D activities on the CAFE Project, suspending activities on three new sensor technologies, and continuing development o f two others. The model has also been used to justify the development of a new prognostic approach for diagnosing machine health using COTS equipment and a new algorithmic approach. maintaining current operations and allows for a method to calculate economic indices of performance that can be used as control points in deciding whether to continue development or suspend actions. The model can also be used as an integral part of an overall control loop utilizing real-time process data from the sensor groups to make production decisions (stop production and repair machine, continue and warn of anticipated problems, queue for repairs, etc.).

  17. Application of the Beck model to stock markets: Value-at-Risk and portfolio risk assessment

    NASA Astrophysics Data System (ADS)

    Kozaki, M.; Sato, A.-H.

    2008-02-01

    We apply the Beck model, developed for turbulent systems that exhibit scaling properties, to stock markets. Our study reveals that the Beck model elucidates the properties of stock market returns and is applicable to practical use such as the Value-at-Risk estimation and the portfolio analysis. We perform empirical analysis with daily/intraday data of the S&P500 index return and find that the volatility fluctuation of real markets is well-consistent with the assumptions of the Beck model: The volatility fluctuates at a much larger time scale than the return itself and the inverse of variance, or “inverse temperature”, β obeys Γ-distribution. As predicted by the Beck model, the distribution of returns is well-fitted by q-Gaussian distribution of Tsallis statistics. The evaluation method of Value-at-Risk (VaR), one of the most significant indicators in risk management, is studied for q-Gaussian distribution. Our proposed method enables the VaR evaluation in consideration of tail risk, which is underestimated by the variance-covariance method. A framework of portfolio risk assessment under the existence of tail risk is considered. We propose a multi-asset model with a single volatility fluctuation shared by all assets, named the single β model, and empirically examine the agreement between the model and an imaginary portfolio with Dow Jones indices. It turns out that the single β model gives good approximation to portfolios composed of the assets with non-Gaussian and correlated returns.

  18. Prevalence and Risk Factors of Elevated Blood Pressure, Overweight, and Dyslipidemia in Adolescent and Young Adults in Rural Nepal

    PubMed Central

    Stewart, Christine P.; Wu, Lee S.F.; LeClerq, Steven C.; Khatry, Subarna K.; West, Keith P.

    2013-01-01

    Abstract Background Chronic disease begins early in life, yet population data are sparse on potential causal factors in children and young adults in South Asia. Methods We assessed risk factors for chronic disease in two population cohorts, aged 9–23 years, in rural Nepal. Assessed variables included short height (less than −2 z), high body mass index (BMI) (z>0.42), waist circumference (WC) >90 cm (male) or 80 cm (female) or age-adjusted child cutoff], high blood pressure (>120/80 mmHg), fasting glucose (≥100 mg/dL), glycosylated hemoglobin (HbA1c) (>7%), blood lipids [triglyceride, high-density lipoprotein cholesterol (HDL-C), and total cholesterol], diet, smoking, alcohol, and socioeconomic status (SES) factors. Results The population was stunted (46%) and few were overweight (∼2%–4% with high BMI or WC). Twelve percent had high blood pressure. Plasma hypertriglyceridemia (≥150 mg/dL) affected ∼8.5%, and 78% had low HDL-C concentrations <40 mg/dL (male) or <50 mg/dL (female)], while few (≤3%) had elevated total cholesterol (≥180 mg/dL), glucose, and HbA1c. Females were at higher risk than males for high blood pressure [odds ratio (OR) 1.9; 95% confidence interval (CI) 1.6–2.3] and overweight (4.2; 3.0–5.8), but had lower risk of dyslipidemia (0.7; 0.6–0.9). Ethnic plains Madheshi were less likely to be overweight (0.3; 0.2–0.4), but had greater risk of dyslipidemia (1.4; 1.1–1.7) versus those of Hill origin. Some dietary factors were significantly associated with high blood pressure or dyslipidemia, but not overweight. Conclusions Dyslipidemia and high blood pressure are emerging health concerns among young adults in rural Nepal. PMID:23682595

  19. Thermodynamically consistent modeling of granular-fluid mixtures incorporating pore pressure evolution and hypoplastic behavior

    NASA Astrophysics Data System (ADS)

    Heß, Julian; Wang, Yongqi; Hutter, Kolumban

    2017-01-01

    This paper presents a new, thermodynamically consistent model for granular-fluid mixtures, derived with the entropy principle of Müller and Liu. Including a pressure diffusion equation combined with the concept of extra pore pressure, and hypoplastic material behavior, thermodynamic restrictions are imposed on the constitutive quantities. The model is applied to a granular-fluid flow, using a closing assumption in conjunction with the fluid pressure. While the focal point of the work is the conceptional part, i.e. the thermodynamic consistent modeling, numerical simulations with physically reasonable results for simple shear flow are also carried out.

  20. Non-Gaussian PDF Modeling of Turbulent Boundary Layer Fluctuating Pressure Excitation

    NASA Technical Reports Server (NTRS)

    Steinwolf, Alexander; Rizzi, Stephen A.

    2003-01-01

    The purpose of the study is to investigate properties of the probability density function (PDF) of turbulent boundary layer fluctuating pressures measured on the exterior of a supersonic transport aircraft. It is shown that fluctuating pressure PDFs differ from the Gaussian distribution even for surface conditions having no significant discontinuities. The PDF tails are wider and longer than those of the Gaussian model. For pressure fluctuations upstream of forward-facing step discontinuities and downstream of aft-facing step discontinuities, deviations from the Gaussian model are more significant and the PDFs become asymmetrical. Various analytical PDF distributions are used and further developed to model this behavior.

  1. Angiography, scintigraphy, intraosseous pressure, and histologic findings in high-risk osteonecrotic femoral heads with negative magnetic resonance images.

    PubMed

    Koo, K H; Kim, R; Cho, S H; Song, H R; Lee, G; Ko, G H

    1994-11-01

    One hundred twenty-six hips of 68 patients who were suspected of having osteonecrosis or being at risk for osteonecrosis were studied with magnetic resonance (MR) imaging. Abnormal patterns on MR imaging characteristic of osteonecrosis were observed in 98 hips. The remaining 28 hips (22 patients) with negative MR images underwent superselective angiography of the medial femoral circumflex artery. Angiography showed interruption of the superior retinacular arteries in 13 hips (12 patients), including 6 of 7 symptomatic hips. Bone scans were performed on 8 of 13 hips angiographically positive for osteonecrosis. Decrease of radionuclide uptake (cold lesions) was observed in all 8 of these femoral heads. Thirteen femoral heads with interruption of superior retinacular arteries underwent intraosseous pressure measurement and core biopsy. Intraosseous pressure was elevated in 11 hips. The results of histologic study showed evidence of early necrosis in 10 femoral heads. This study indicates that there are a considerable number of femoral heads at high risk, even when they have negative MR images. They do, however, show positive findings on angiography, scintigraphy (cold lesions), intraosseous pressure measurement, and histologic study.

  2. A General Pressure Gradient Formulation for Ocean Models - Part II: Energy, Momentum, and Bottom Torque Consistency

    NASA Technical Reports Server (NTRS)

    Song, Y.; Wright, D.

    1998-01-01

    A formulation of the pressure gradient force for use in models with topography-following coordinates is proposed and diagnostically analyzed by Song. We investigate numerical consistency with respect to global energy conservation, depth-integrated momentum changes, and the represent of the bottom pressure torque.

  3. Testing a Model of Resistance to Peer Pressure among Mexican-Origin Adolescents

    ERIC Educational Resources Information Center

    Bamaca, Mayra Y.; Umana-Taylor, Adriana J.

    2006-01-01

    This study examined the factors associated with resistance to peer pressure toward antisocial behaviors among a sample of Mexican-origin adolescents (n=564) living in a large Southwestern city in the U.S. A model examining the influence of generational status, emotional autonomy from parents, and self-esteem on resistance to peer pressure was…

  4. Periodically Relieving Ischial Sitting Load to Decrease the Risk of Pressure Ulcers

    PubMed Central

    Makhsous, Mohsen; Rowles, Diane M.; Rymer, William Z.; Bankard, James; Nam, Ellis K.; Chen, David; Lin, Fang

    2010-01-01

    Objective To investigate the relieving effect on interface pressure of an alternate sitting protocol involving a sitting posture that reduces ischial support. Design Repeated measures in 2 protocols on 3 groups of subjects. Setting Laboratory. Participants Twenty able-bodied persons, 20 persons with paraplegia, and 20 persons with tetraplegia. Interventions Two 1-hour protocols were used: alternate and normal plus pushup. In the alternate protocol, sitting posture was alternated every 10 minutes between normal (sitting upright with ischial support) and with partially removed ischial support (WO-BPS) postures; in the normal plus pushup protocol, sitting was in normal posture with pushups (lifting the subject off the seat) performed every 20 minutes. Main Outcome Measure Interface pressure on seat and backrest. Results In WO-BPS posture, the concentrated interface pressure observed around the ischia in normal posture was significantly repositioned to the thighs. By cyclically repositioning the interface pressure, the alternate protocol was superior to the normal plus pushup protocol in terms of a significantly lower average interface pressure over the buttocks. Conclusions A sitting protocol periodically reducing the ischial support helps lower the sitting load on the buttocks, especially the area close to ischial tuberosities. PMID:17601466

  5. Carotid Artery IMT, Blood Pressure, and Cardiovascular Risk Factors in Males and Females

    PubMed Central

    CROMWELL, CHRISTINA M.; AICHELE, KRISTIN R.; OAKMAN, JOYANN E.; NEAL, MICHAEL P.; LENZO, JESSICA M.; PEREZ, AVERY N.; BYE, NAOMI L.; SANTANIELLO, ERICA L.; HILL, JESSICA A.; EVANS, RACHEL C.; THIELE, KARLA A.; CHAVIS, LAUREN N.; GETTY, ALLYSON K.; WISDO, TIA R.; FEAIRHELLER, DEBORAH L.

    2016-01-01

    Previous studies have investigated carotid artery intima-media thickness (IMT) and blood pressure and found a direct correlation between the two. It is known that adult females have better cardiovascular health than males until a certain stage of life, yet limited research has examined gender differences in vascular function. Thus, the purpose of this study was to investigate vascular structure and function, blood pressure, and blood glucose/cholesterol levels in relation to gender differences in young healthy adults. On three separate days, 44 adults (26.30 ± 11.9yrs; 24M, 20F) completed a carotid IMT ultrasound, a flow-mediated dilation (FMD), a fasted glucose and cholesterol test, a 24hr ambulatory blood pressure monitoring, a VO2max test, and a body composition measurement. Females had lower systolic blood pressure, lower diastolic blood pressure, lower LDL/HDL ratios, lower body mass index, a higher HDL count, and lower plasma glucose levels than males (p < 0.05 for all), all of which suggest better cardiovascular health. However, we found no gender differences in vascular health measures, IMT and FMD. Our results suggest that while young adult females have better cardiovascular health than males, endothelial function may not yet be affected in the young adult years. PMID:27766134

  6. Artificial arterial blood pressure artifact models and an evaluation of a robust blood pressure and heart rate estimator

    PubMed Central

    Li, Qiao; Mark, Roger G; Clifford, Gari D

    2009-01-01

    Background Within the intensive care unit (ICU), arterial blood pressure (ABP) is typically recorded at different (and sometimes uneven) sampling frequencies, and from different sensors, and is often corrupted by different artifacts and noise which are often non-Gaussian, nonlinear and nonstationary. Extracting robust parameters from such signals, and providing confidences in the estimates is therefore difficult and requires an adaptive filtering approach which accounts for artifact types. Methods Using a large ICU database, and over 6000 hours of simultaneously acquired electrocardiogram (ECG) and ABP waveforms sampled at 125 Hz from a 437 patient subset, we documented six general types of ABP artifact. We describe a new ABP signal quality index (SQI), based upon the combination of two previously reported signal quality measures weighted together. One index measures morphological normality, and the other degradation due to noise. After extracting a 6084-hour subset of clean data using our SQI, we evaluated a new robust tracking algorithm for estimating blood pressure and heart rate (HR) based upon a Kalman Filter (KF) with an update sequence modified by the KF innovation sequence and the value of the SQI. In order to do this, we have created six novel models of different categories of artifacts that we have identified in our ABP waveform data. These artifact models were then injected into clean ABP waveforms in a controlled manner. Clinical blood pressure (systolic, mean and diastolic) estimates were then made from the ABP waveforms for both clean and corrupted data. The mean absolute error for systolic, mean and diastolic blood pressure was then calculated for different levels of artifact pollution to provide estimates of expected errors given a single value of the SQI. Results Our artifact models demonstrate that artifact types have differing effects on systolic, diastolic and mean ABP estimates. We show that, for most artifact types, diastolic ABP estimates are

  7. Improving default risk prediction using Bayesian model uncertainty techniques.

    PubMed

    Kazemi, Reza; Mosleh, Ali

    2012-11-01

    Credit risk is the potential exposure of a creditor to an obligor's failure or refusal to repay the debt in principal or interest. The potential of exposure is measured in terms of probability of default. Many models have been developed to estimate credit risk, with rating agencies dating back to the 19th century. They provide their assessment of probability of default and transition probabilities of various firms in their annual reports. Regulatory capital requirements for credit risk outlined by the Basel Committee on Banking Supervision have made it essential for banks and financial institutions to develop sophisticated models in an attempt to measure credit risk with higher accuracy. The Bayesian framework proposed in this article uses the techniques developed in physical sciences and engineering for dealing with model uncertainty and expert accuracy to obtain improved estimates of credit risk and associated uncertainties. The approach uses estimates from one or more rating agencies and incorporates their historical accuracy (past performance data) in estimating future default risk and transition probabilities. Several examples demonstrate that the proposed methodology can assess default probability with accuracy exceeding the estimations of all the individual models. Moreover, the methodology accounts for potentially significant departures from "nominal predictions" due to "upsetting events" such as the 2008 global banking crisis.

  8. Patient-specific modeling of blood flow and pressure in human coronary arteries.

    PubMed

    Kim, H J; Vignon-Clementel, I E; Coogan, J S; Figueroa, C A; Jansen, K E; Taylor, C A

    2010-10-01

    Coronary flow is different from the flow in other parts of the arterial system because it is influenced by the contraction and relaxation of the heart. To model coronary flow realistically, the compressive force of the heart acting on the coronary vessels needs to be included. In this study, we developed a method that predicts coronary flow and pressure of three-dimensional epicardial coronary arteries by considering models of the heart and arterial system and the interactions between the two models. For each coronary outlet, a lumped parameter coronary vascular bed model was assigned to represent the impedance of the downstream coronary vascular networks absent in the computational domain. The intramyocardial pressure was represented with either the left or right ventricular pressure depending on the location of the coronary arteries. The left and right ventricular pressure were solved from the lumped parameter heart models coupled to a closed loop system comprising a three-dimensional model of the aorta, three-element Windkessel models of the rest of the systemic circulation and the pulmonary circulation, and lumped parameter models for the left and right sides of the heart. The computed coronary flow and pressure and the aortic flow and pressure waveforms were realistic as compared to literature data.

  9. Crisis and emergency risk communication as an integrative model.

    PubMed

    Reynolds, Barbara; W Seeger, Matthew

    2005-01-01

    This article describes a model of communication known as crisis and emergency risk communication (CERC). The model is outlined as a merger of many traditional notions of health and risk communication with work in crisis and disaster communication. The specific kinds of communication activities that should be called for at various stages of disaster or crisis development are outlined. Although crises are by definition uncertain, equivocal, and often chaotic situations, the CERC model is presented as a tool health communicators can use to help manage these complex events.

  10. Blunted sleep-time relative blood pressure decline increases cardiovascular risk independent of blood pressure level--the "normotensive non-dipper" paradox.

    PubMed

    Hermida, Ramón C; Ayala, Diana E; Mojón, Artemio; Fernández, José R

    2013-03-01

    Numerous studies have consistently shown an association between blunted sleep-time relative blood pressure (BP) decline (non-dipping) and increased cardiovascular disease (CVD) risk in hypertension. Normotensive persons with a non-dipper BP profile also have increased target organ damage, namely, increased left ventricular mass and relative wall thickness, reduced myocardial diastolic function, increased urinary albumin excretion, increased prevalence of diabetic retinopathy, and impaired glucose tolerance. It remains a point of contention, however, whether the non-dipper BP pattern or just elevated BP, alone, is the most important predictor of advanced target organ damage and future CVD events. Accordingly, we investigated the role of dipping status and ambulatory BP level as contributing factors for CVD morbidity and mortality in the MAPEC (Monitorización Ambulatoria para Predicción de Eventos Cardiovasculares, i.e., Ambulatory Blood Pressure Monitoring for Prediction of Cardiovascular Events) study. We prospectively studied 3344 individuals (1718 men/1626 women), 52.6 ± 14.5 (mean ± SD) yrs of age, during a median follow-up of 5.6 yrs. BP was measured by ambulatory monitoring (ABPM) for 48 h at baseline, and again annually or more frequently (quarterly) if treatment adjustment was required in treated hypertensive patients. At baseline, those with ABPM-substantiated hypertension were randomized to one of two treatment-time regimen groups: (i) ingestion of all prescribed hypertension medications upon awakening or (ii) ingestion of the entire dose of ≥1 of them at bedtime. Those found to be normotensive at baseline were untreated but followed and evaluated by repeated ABPM like the hypertensive patients. Participants were divided into four investigated categories on the basis of dipping status and ambulatory BP: (i) dipper vs. non-dipper, and (ii) normal ambulatory BP if the awake systolic (SBP)/diastolic (DBP) BP means were <135/85 mm Hg and the

  11. Large scale modelling of salmon lice (Lepeophtheirus salmonis) infection pressure based on lice monitoring data from Norwegian salmonid farms.

    PubMed

    Kristoffersen, Anja B; Jimenez, Daniel; Viljugrein, Hildegunn; Grøntvedt, Randi; Stien, Audun; Jansen, Peder A

    2014-12-01

    Infection by parasitic sea lice is a substantial problem in industrial scale salmon farming. To control the problem, Norwegian salmonid farms are not permitted to exceed a threshold level of infection on their fish, and farms are required to monitor and report lice levels on a weekly basis to ensure compliance with the regulation. In the present study, we combine the monitoring data with a deterministic model for salmon lice population dynamics to estimate farm production of infectious lice stages. Furthermore, we use an empirical estimate of the relative risk of salmon lice transmission between farms, that depend on inter-farm distances, to estimate the external infection pressure at a farm site, i.e. the infection pressure from infective salmon lice of neighbouring farm origin. Finally, we test whether our estimates of infection pressure from neighbouring farms as well as internal within farm infection pressure, predicts subsequent development of infection in cohorts of farmed salmonids in their initial phase of marine production. We find that estimated external infection pressure is a main predictor of salmon lice population dynamics in newly stocked cohorts of salmonids. Our results emphasize the importance of keeping the production of infectious lice stages at low levels within local networks of salmon farms. Our model can easily be implemented for real time estimation of infection pressure at the national scale, utilizing the masses of data generated through the compulsory lice monitoring in salmon farms. The implementation of such a system should give the salmon industry greater predictability with respect to salmon lice infection levels, and aid the decision making process when the development of new farm sites are planned.

  12. Model changes improve compressor-station piping pressure-loss predictions

    SciTech Connect

    Meyer, T.R.

    1985-04-29

    This article explains steps taken to modify loss calculations to predict more accurately pressure losses in the station piping systems of Texas Gas. The article does not attempt to set any industry standards for determining pressure drop in station piping. Its purposes are to point out that problems exist in current methods used for calculating station piping pressure losses, to show that manufacturer estimates of pressure drop may not always reflect actual conditions, and to outline the procedure used by Texas Gas to model more accurately compressor station piping.

  13. HIGH TEMPERATURE HIGH PRESSURE THERMODYNAMIC MEASUREMENTS FOR COAL MODEL COMPOUNDS

    SciTech Connect

    Vinayak N. Kabadi

    2000-05-01

    The Vapor Liquid Equilibrium measurement setup of this work was first established several years ago. It is a flow type high temperature high pressure apparatus which was designed to operate below 500 C temperature and 2000 psia pressure. Compared with the static method, this method has three major advantages: the first is that large quantity of sample can be obtained from the system without disturbing the equilibrium state which was established before; the second is that the residence time of the sample in the equilibrium cell is greatly reduced, thus decomposition or contamination of the sample can be effectively prevented; the third is that the flow system allows the sample to degas as it heats up since any non condensable gas will exit in the vapor stream, accumulate in the vapor condenser, and not be recirculated. The first few runs were made with Quinoline-Tetralin system, the results were fairly in agreement with the literature data . The former graduate student Amad used the same apparatus acquired the Benzene-Ethylbenzene system VLE data. This work used basically the same setup (several modifications had been made) to get the VLE data of Ethylbenzene-Quinoline system.

  14. Empirical Analysis of Farm Credit Risk under the Structure Model

    ERIC Educational Resources Information Center

    Yan, Yan

    2009-01-01

    The study measures farm credit risk by using farm records collected by Farm Business Farm Management (FBFM) during the period 1995-2004. The study addresses the following questions: (1) whether farm's financial position is fully described by the structure model, (2) what are the determinants of farm capital structure under the structure model, (3)…

  15. A promoter polymorphism in APJ gene is significantly associated with blood pressure changes and hypertension risk in Chinese women

    PubMed Central

    Zhao, Dalong; He, Lan; Zheng, Lihong; Xue, Jing; Wang, Bin; Pan, Hongming

    2016-01-01

    The aim of this study was to interrogate the gender-specific association of 5 well-defined polymorphisms in apelin/APJ system with both blood pressure changes and hypertension risk in a northeastern Chinese population. This is a population-based case-control study, including 650 hypertensive patients and 645 normotensive controls. Data were analyzed by STATA and Haplo.Stats. The genotype distributions of 5 study polymorphisms were in Hardy-Weinberg equilibrium in both genders. The rs7119375 and rs10501367 were completely linked. The genotypes (P = 0.001) and alleles (P < 0.001) of rs7119375 differed significantly between patients and controls in women. Carriers of rs7119375-AA genotype had significant higher systolic blood pressure (SBP) than carriers of rs7119375-GG genotype in both patients and controls of female gender (P < 0.01). Moreover, carriers of rs7119375-A allele were 1.80 times more likely to develop hypertension relative to carriers of rs7119375-GG genotype after adjusting for age, body mass index and glucose (odds ratio: 1.80; 95% confidence interval: 1.03–3.16; P = 0.040). Further allele combination analysis supported the leading contribution of rs7119375 to hypertension risk. Our findings demonstrated that the mutation of promoter polymorphism rs7119375 in APJ gene was significantly associated with elevated SBP and increased hypertension risk in Chinese women. PMID:27863393

  16. Dental caries: an updated medical model of risk assessment.

    PubMed

    Kutsch, V Kim

    2014-04-01

    Dental caries is a transmissible, complex biofilm disease that creates prolonged periods of low pH in the mouth, resulting in a net mineral loss from the teeth. Historically, the disease model for dental caries consisted of mutans streptococci and Lactobacillus species, and the dental profession focused on restoring the lesions/damage from the disease by using a surgical model. The current recommendation is to implement a risk-assessment-based medical model called CAMBRA (caries management by risk assessment) to diagnose and treat dental caries. Unfortunately, many of the suggestions of CAMBRA have been overly complicated and confusing for clinicians. The risk of caries, however, is usually related to just a few common factors, and these factors result in common patterns of disease. This article examines the biofilm model of dental caries, identifies the common disease patterns, and discusses their targeted therapeutic strategies to make CAMBRA more easily adaptable for the privately practicing professional.

  17. Modeling of Flood Risk for the Continental United States

    NASA Astrophysics Data System (ADS)

    Lohmann, D.; Li, S.; Katz, B.; Goteti, G.; Kaheil, Y. H.; Vojjala, R.

    2011-12-01

    The science of catastrophic risk modeling helps people to understand the physical and financial implications of natural catastrophes (hurricanes, flood, earthquakes, etc.), terrorism, and the risks associated with changes in life expectancy. As such it depends on simulation techniques that integrate multiple disciplines such as meteorology, hydrology, structural engineering, statistics, computer science, financial engineering, actuarial science, and more in virtually every field of technology. In this talk we will explain the techniques and underlying assumptions of building the RMS US flood risk model. We especially will pay attention to correlation (spatial and temporal), simulation and uncertainty in each of the various components in the development process. Recent extreme floods (e.g. US Midwest flood 2008, US Northeast flood, 2010) have increased the concern of flood risk. Consequently, there are growing needs to adequately assess the flood risk. The RMS flood hazard model is mainly comprised of three major components. (1) Stochastic precipitation simulation module based on a Monte-Carlo analogue technique, which is capable of producing correlated rainfall events for the continental US. (2) Rainfall-runoff and routing module. A semi-distributed rainfall-runoff model was developed to properly assess the antecedent conditions, determine the saturation area and runoff. The runoff is further routed downstream along the rivers by a routing model. Combined with the precipitation model, it allows us to correlate the streamflow and hence flooding from different rivers, as well as low and high return-periods across the continental US. (3) Flood inundation module. It transforms the discharge (output from the flow routing) into water level, which is further combined with a two-dimensional off-floodplain inundation model to produce comprehensive flood hazard map. The performance of the model is demonstrated by comparing to the observation and published data. Output from

  18. Model for Solar Proton Risk Assessment

    NASA Technical Reports Server (NTRS)

    Xapos, M. A.; Stauffer, C.; Gee, G. B.; Barth, J. L.; Stassinopoulos, E. G.; McGuire, R. E.

    2004-01-01

    A statistical model for cumulative solar proton event fluences during space missions is presented that covers both the solar minimum and solar maximum phases of the solar cycle. It is based on data from the IMP and GOES series of satellites that is integrated together to allow the best features of each data set to be taken advantage of. This allows fluence-energy spectra to be extended out to energies of 327 MeV.

  19. Parametric Estimation in a Recurrent Competing Risks Model.

    PubMed

    Taylor, Laura L; Peña, Edsel A

    2013-01-01

    A resource-efficient approach to making inferences about the distributional properties of the failure times in a competing risks setting is presented. Efficiency is gained by observing recurrences of the competing risks over a random monitoring period. The resulting model is called the recurrent competing risks model (RCRM) and is coupled with two repair strategies whenever the system fails. Maximum likelihood estimators of the parameters of the marginal distribution functions associated with each of the competing risks and also of the system lifetime distribution function are presented. Estimators are derived under perfect and partial repair strategies. Consistency and asymptotic properties of the estimators are obtained. The estimation methods are applied to a data set of failures for cars under warranty. Simulation studies are used to ascertain the small sample properties and the efficiency gains of the resulting estimators.

  20. Intracochlear pressure measurements in scala media inform models of cochlear mechanics

    NASA Astrophysics Data System (ADS)

    Kale, Sushrut; Olson, Elizabeth S.

    2015-12-01

    In the classic view of cochlear mechanics, the cochlea is comprised of two identical fluid chambers separated by the cochlear partition (CP). In this view the traveling wave pressures in the two chambers mirror each other; they are equal in magnitude and opposite in phase. A fast pressure mode adds approximately uniformly. More recent models of cochlear mechanics take into account the structural complexity of the CP and the resulting additional mechanical modes would lead to distinct (non-symmetric) patterns of pressure and motion on the two sides of the CP. However, there was little to no physiological data that explored these predictions. To this aim, we measured intracochlear fluid pressure in scala media (SM), including measurements close to the sensory tissue, using miniaturized pressure sensors (˜ 80 μm outer diameter). Measurements were made in-vivo from the basal cochlear turn in gerbils. SM pressure was measured at two longitudinal locations in different preparations. In a subset of the experiments SM and ST (scala tympani) pressures were measured at the same longitudinal location. Traveling wave pressures were observed in both SM and ST, and showed the relative phase predicted by the classical theory. In addition, SM pressure showed spatial variations that had not been observed in ST, which points to a relatively complex CP motion on the SM side. These data both underscore the first-order validity of the classic cochlear traveling wave model, and open a new view to CP mechanics.

  1. More Young Adults at Risk for High Blood Pressure | NIH MedlinePlus the Magazine

    MedlinePlus

    ... leading to various, serious health problems, ranging from hardening of the arteries, stroke, and brain hemorrhage to ... things, smoking damages blood vessel walls and speeds hardening of the arteries. Ceasing smoking reduces the risk ...

  2. Finite element analysis to characterize how varying patellar loading influences pressure applied to cartilage: model evaluation.

    PubMed

    Shah, Kushal S; Saranathan, Archana; Koya, Bharath; Elias, John J

    2015-01-01

    A finite element analysis (FEA) modeling technique has been developed to characterize how varying the orientation of the patellar tendon influences the patellofemoral pressure distribution. To evaluate the accuracy of the technique, models were created from MRI images to represent five knees that were previously tested in vitro to determine the influence of hamstrings loading on patellofemoral contact pressures. Hamstrings loading increased the lateral and posterior orientation of the patellar tendon. Each model was loaded at 40°, 60°, and 80° of flexion with quadriceps force vectors representing the experimental loading conditions. The orientation of the patellar tendon was represented for the loaded and unloaded hamstrings conditions based on experimental measures of tibiofemoral alignment. Similar to the experimental data, simulated loading of the hamstrings within the FEA models shifted the center of pressure laterally and increased the maximum lateral pressure. Significant (p < 0.05) differences were identified for the center of pressure and maximum lateral pressure from paired t-tests carried out at the individual flexion angles. The ability to replicate experimental trends indicates that the FEA models can be used for future studies focused on determining how variations in the orientation of the patellar tendon related to anatomical or loading variations or surgical procedures influence the patellofemoral pressure distribution.

  3. Model based climate information on drought risk in Africa

    NASA Astrophysics Data System (ADS)

    Calmanti, S.; Syroka, J.; Jones, C.; Carfagna, F.; Dell'Aquila, A.; Hoefsloot, P.; Kaffaf, S.; Nikulin, G.

    2012-04-01

    The United Nations World Food Programme (WFP) has embarked upon the endeavor of creating a sustainable Africa-wide natural disaster risk management system. A fundamental building block of this initiative is the setup of a drought impact modeling platform called Africa Risk-View that aims to quantify and monitor weather-related food security risk in Africa. The modeling approach is based the Water Requirement Satisfaction Index (WRSI), as the fundamental indicator of the performances of agriculture and uses historical records of food assistance operation to project future potential needs for livelihood protection. By using climate change scenarios as an input to Africa Risk-View it is possible, in principles, to evaluate the future impact of climate variability on critical issues such as food security and the overall performance of the envisaged risk management system. A necessary preliminary step to this challenging task is the exploration of the sources of uncertainties affecting the assessment based on modeled climate change scenarios. For this purpose, a limited set of climate models have been selected in order verify the relevance of using climate model output data with Africa Risk-View and to explore a minimal range of possible sources of uncertainty. This first evaluation exercise started before the setup of the CORDEX framework and has relied on model output available at the time. In particular only one regional downscaling was available for the entire African continent from the ENSEMBLES project. The analysis shows that current coarse resolution global climate models can not directly feed into the Africa RiskView risk-analysis tool. However, regional downscaling may help correcting the inherent biases observed in the datasets. Further analysis is performed by using the first data available under the CORDEX framework. In particular, we consider a set of simulation driven with boundary conditions from the reanalysis ERA-Interim to evaluate the skill drought

  4. Molecular modeling simulations in phase stability of polyethylene solutions at elevated pressures

    NASA Astrophysics Data System (ADS)

    Shahamat, Moeed; Rey, Alejandro D.

    2013-03-01

    Molecular dynamics (MD) simulations using the OPLS-AA force field are conducted to compute pressure, molecular weight dependence of Hildebrand's solubility parameters (SP) and density of hexane and high-density polyethylene (HDPE) at high pressures from 100 to 3000 bar. The electrostatic energy contribution to the cohesive energy and density leads to increases in the SP with pressure for molecular mechanical models (MMM) with and without electrostatic terms. The Flory-Huggins interaction parameter (IP) predicted from the pressure dependence of SPs and molar volumes decreases upon increasing pressure, indicating that miscibility improves by raising pressure. This is consistent with the solution polymerization process for producing PE, where pressure-induced phase separation (PIPS) is used to separate the polymer from solution. Exclusion of electrostatic potentials in the MMM results in larger IPs while the decreasing trend remains intact with and without electrostatic forces. There is a pressure limit beyond which the IP has less sensitivity to pressure indicating that PE miscibility is not further affected. It is shown that pressure increases the chemical potential factor of the phase stability condition, stabilizing the solution. These results contribute to the fundamental understanding of PIPS, an important demixing process poorly understood when compared to thermally-induced phase separation.

  5. Motivational barriers to retention of at-risk young adults in HIV-prevention interventions: perceived pressure and efficacy.

    PubMed

    Liu, Jiaying; Jones, Christopher; Wilson, Kristina; Durantini, Marta R; Livingood, William; Albarracín, Dolores

    2014-01-01

    Multi-session HIV-prevention interventions are efficacious but depend on the retention of clients over time. In a sample of at-risk young adults (N = 386), we investigated three potential motivational barriers that might affect the likelihood of retention. Perceived pressure, perceived efficacy and fear and anxiety during the initial session were measured, along with demographic characteristics, partner characteristics, and HIV-related health knowledge. Logistic regressions demonstrated that (1) in general, perceived ineffectiveness was negatively associated with retention; (2) perceived pressure or coercion was negatively associated with retention but only for younger clients; (3) experienced fear and anxiety had no significant association with retention. Implications for theory and counseling practices to reduce motivational barriers and effectively tailor interventions are discussed.

  6. Motivational barriers to retention of at-risk young adults in HIV-prevention interventions: Perceived pressure and efficacy

    PubMed Central

    Liu, Jiaying; Jones, Christopher; Wilson, Kristina; Durantini, Marta R.; Livingood, William; Albarracín, Dolores

    2014-01-01

    Multi-session HIV-prevention interventions are efficacious but depend on the retention of clients over time. In a sample of at-risk young adults (N = 386), we investigated three potential motivational barriers that might affect the likelihood of retention. Perceived pressure, perceived efficacy and fear and anxiety during the initial session were measured, along with demographic characteristics, partner characteristics, and HIV-related health knowledge. Logistic regression demonstrated that (1) in general, perceived ineffectiveness was negatively associated with retention; (2) perceived pressure or coercion was negatively associated with retention, but only for younger clients; (3) experienced fear and anxiety had no significant association with retention. Implications for theory and counseling practices to reduce motivational barriers and effectively tailor interventions are discussed. PMID:24641552

  7. Credibility analysis of risk classes by generalized linear model

    NASA Astrophysics Data System (ADS)

    Erdemir, Ovgucan Karadag; Sucu, Meral

    2016-06-01

    In this paper generalized linear model (GLM) and credibility theory which are frequently used in nonlife insurance pricing are combined for reliability analysis. Using full credibility standard, GLM is associated with limited fluctuation credibility approach. Comparison criteria such as asymptotic variance and credibility probability are used to analyze the credibility of risk classes. An application is performed by using one-year claim frequency data of a Turkish insurance company and results of credible risk classes are interpreted.

  8. Model-based benefit-risk assessment: can Archimedes help?

    PubMed

    Krishna, R

    2009-03-01

    In December 2008, the US Food and Drug Administration issued a new draft Guidance for Industry on Diabetes Mellitus--evaluating cardiovascular risk in new antidiabetic therapies to treat Type 2 diabetes. This guidance comes at a time when recent discussions have focused on delineation of cardiovascular risk reduction for new antidiabetic drugs. Computational tools that can enable early prediction of cardiovascular risk are reviewed with specific reference to Archimedes (Kaiser Permanente), with an aim of proposing a model-based solution and enabling decisions to be made as early as possible in the drug development value chain.

  9. PEP-II vacuum system pressure profile modeling using EXCEL

    SciTech Connect

    Nordby, M.; Perkins, C.

    1994-06-01

    A generic, adaptable Microsoft EXCEL program to simulate molecular flow in beam line vacuum systems is introduced. Modeling using finite-element approximation of the governing differential equation is discussed, as well as error estimation and program capabilities. The ease of use and flexibility of the spreadsheet-based program is demonstrated. PEP-II vacuum system models are reviewed and compared with analytical models.

  10. New empirically-derived solar radiation pressure model for GPS satellites

    NASA Technical Reports Server (NTRS)

    Bar-Sever, Y.; Kuang, D.

    2003-01-01

    Solar radiation pressure force is the second largest perturbation acting on GPS satellites, after the gravitational attraction from the Earth, Sun, and Moon. It is the largest error source in the modeling of GPS orbital dynamics.

  11. Moving Model Test of High-Speed Train Aerodynamic Drag Based on Stagnation Pressure Measurements.

    PubMed

    Yang, Mingzhi; Du, Juntao; Li, Zhiwei; Huang, Sha; Zhou, Dan

    2017-01-01

    A moving model test method based on stagnation pressure measurements is proposed to measure the train aerodynamic drag coefficient. Because the front tip of a high-speed train has a high pressure area and because a stagnation point occurs in the center of this region, the pressure of the stagnation point is equal to the dynamic pressure of the sensor tube based on the obtained train velocity. The first derivation of the train velocity is taken to calculate the acceleration of the train model ejected by the moving model system without additional power. According to Newton's second law, the aerodynamic drag coefficient can be resolved through many tests at different train speeds selected within a relatively narrow range. Comparisons are conducted with wind tunnel tests and numerical simulations, and good agreement is obtained, with differences of less than 6.1%. Therefore, the moving model test method proposed in this paper is feasible and reliable.

  12. Moving Model Test of High-Speed Train Aerodynamic Drag Based on Stagnation Pressure Measurements

    PubMed Central

    Yang, Mingzhi; Du, Juntao; Huang, Sha; Zhou, Dan

    2017-01-01

    A moving model test method based on stagnation pressure measurements is proposed to measure the train aerodynamic drag coefficient. Because the front tip of a high-speed train has a high pressure area and because a stagnation point occurs in the center of this region, the pressure of the stagnation point is equal to the dynamic pressure of the sensor tube based on the obtained train velocity. The first derivation of the train velocity is taken to calculate the acceleration of the train model ejected by the moving model system without additional power. According to Newton’s second law, the aerodynamic drag coefficient can be resolved through many tests at different train speeds selected within a relatively narrow range. Comparisons are conducted with wind tunnel tests and numerical simulations, and good agreement is obtained, with differences of less than 6.1%. Therefore, the moving model test method proposed in this paper is feasible and reliable. PMID:28095441

  13. Risk Prediction Models for Lung Cancer: A Systematic Review.

    PubMed

    Gray, Eoin P; Teare, M Dawn; Stevens, John; Archer, Rachel

    2016-03-01

    Many lung cancer risk prediction models have been published but there has been no systematic review or comprehensive assessment of these models to assess how they could be used in screening. We performed a systematic review of lung cancer prediction models and identified 31 articles that related to 25 distinct models, of which 11 considered epidemiological factors only and did not require a clinical input. Another 11 articles focused on models that required a clinical assessment such as a blood test or scan, and 8 articles considered the 2-stage clonal expansion model. More of the epidemiological models had been externally validated than the more recent clinical assessment models. There was varying discrimination, the ability of a model to distinguish between cases and controls, with an area under the curve between 0.57 and 0.879 and calibration, the model's ability to assign an accurate probability to an individual. In our review we found that further validation studies need to be considered; especially for the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial 2012 Model Version (PLCOM2012) and Hoggart models, which recorded the best overall performance. Future studies will need to focus on prediction rules, such as optimal risk thresholds, for models for selective screening trials. Only 3 validation studies considered prediction rules when validating the models and overall the models were validated using varied tests in distinct populations, which made direct comparisons difficult. To improve this, multiple models need to be tested on the same data set with considerations for sensitivity, specificity, model accuracy, and positive predictive values at the optimal risk thresholds.

  14. Sensitivity Analysis of Launch Vehicle Debris Risk Model

    NASA Technical Reports Server (NTRS)

    Gee, Ken; Lawrence, Scott L.

    2010-01-01

    As part of an analysis of the loss of crew risk associated with an ascent abort system for a manned launch vehicle, a model was developed to predict the impact risk of the debris resulting from an explosion of the launch vehicle on the crew module. The model consisted of a debris catalog describing the number, size and imparted velocity of each piece of debris, a method to compute the trajectories of the debris and a method to calculate the impact risk given the abort trajectory of the crew module. The model provided a point estimate of the strike probability as a function of the debris catalog, the time of abort and the delay time between the abort and destruction of the launch vehicle. A study was conducted to determine the sensitivity of the strike probability to the various model input parameters and to develop a response surface model for use in the sensitivity analysis of the overall ascent abort risk model. The results of the sensitivity analysis and the response surface model are presented in this paper.

  15. Evaluation of a Single-Channel Nasal Pressure Device to Assess Obstructive Sleep Apnea Risk in Laboratory and Home Environments

    PubMed Central

    Crowley, Kate E.; Rajaratnam, Shantha M.W.; Shea, Steven A.; Epstein, Lawrence J.; Czeisler, Charles A.; Lockley, Steven W.

    2013-01-01

    Study Objectives: To evaluate the sensitivity and specificity of a portable single-channel (intra-nasal pressure) sleep apnea device (ApneaLink) in both the laboratory and at home for assessment of sleep apnea risk in comparison with standard polysomnography (PSG). Methods: Fifty-five participants underwent simultaneous recordings of standard PSG and ApneaLink in the laboratory. Of these, 38 participants also used the ApneaLink device in their own homes for one night. PSG respiratory events were scored using standard criteria. Intra-nasal pressure signals were analyzed using the ApneaLink automated computerized algorithm provided to yield estimates of airflow for detection of apneas and hypopneas. Apnea-hypopnea indices (AHI) were compared. Results: There was high sensitivity and specificity for the ApneaLink AHI when compared to simultaneous PSG at comparable AHI levels (AHI ≥ 15 events/h; sensitivity 100%, specificity 92%; positive and negative predictive values 70% and 100%, respectively). Home-measured ApneaLink AHI sensitivity and specificity were also reliable when compared with PSG (AHI ≥ 5, 81% and 77%, respectively; AHI ≥ 15, 67% and 91%), and improved slightly when two nights' data were used (AHI ≥ 5, 88% and 85%; AHI ≥ 15, 67% and 93%). Conclusions: The ApneaLink demonstrated good sensitivity and specificity in quantifying AHI when compared to PSG in a population with and without confirmed OSA. This simple, easy-to-use device may be useful in de novo large-scale occupational or underserved community OSA diagnostic programs to identify those with unambiguous disease who need immediate treatment or indicate those who may be at increased risk of OSA. Citation: Crowley KE; Rajaratnam SMW; Shea SA; Epstein LJ; Czeisler CA; Lockley SW. Evaluation of a single-channel nasal pressure device to assess obstructive sleep apnea risk in laboratory and home environments. J Clin Sleep Med 2013;9(2):109–116. PMID:23372462

  16. Risk Management Model in Surface Exploitation of Mineral Deposits

    NASA Astrophysics Data System (ADS)

    Stojanović, Cvjetko

    2016-06-01

    Risk management is an integrative part of all types of project management. One of the main tasks of pre-investment studies and other project documentation is the tendency to protect investment projects as much as possible against investment risks. Therefore, the provision and regulation of risk information ensure the identification of the probability of the emergence of adverse events, their forms, causes and consequences, and provides a timely measures of protection against risks. This means that risk management involves a set of management methods and techniques used to reduce the possibility of realizing the adverse events and consequences and thus increase the possibilities of achieving the planned results with minimal losses. Investment in mining projects are of capital importance because they are very complex projects, therefore being very risky, because of the influence of internal and external factors and limitations arising from the socio-economic environment. Due to the lack of a risk management system, numerous organizations worldwide have suffered significant financial losses. Therefore, it is necessary for any organization to establish a risk management system as a structural element of system management system as a whole. This paper presents an approach to a Risk management model in the project of opening a surface coal mine, developed based on studies of extensive scientific literature and personal experiences of the author, and which, with certain modifications, may find use for any investment project, both in the mining industry as well as in investment projects in other areas.

  17. Blood Pressure Control in Hypertensive Patients, Cardiovascular Risk Profile and the Prevalence of Masked Uncontrolled Hypertension (MUCH)

    PubMed Central

    Naser, Nabil; Dzubur, Alen; Durak, Azra; Kulic, Mehmed; Naser, Nura

    2016-01-01

    Introduction: The term masked hypertension (MH) should be used for untreated individuals who have normal office blood pressure but elevated ambulatory blood pressure. For treated patients, this condition should be termed masked uncontrolled hypertension (MUCH). Research Objectives: Masked uncontrolled hypertension (MUCH) has gone unrecognized because few studies have used 24-h ABPM to determine the prevalence of suboptimal BP control in seemingly well-treated patients, and there are few such studies in large cohorts of treated patients attending usual clinical practice. This is important because masked hypertension is associated with a high risk of cardiovascular events. This study was conducted to obtain more information about the association between hypertension and other CV risk factors, about office and ambulatory blood pressure (BP) control as well as on cardiovascular (CV) risk profile in treated hypertensive patients, also to define the prevalence and characteristics of masked uncontrolled hypertension (MUCH) among treated hypertensive patients in routine clinical practice. Patients and methods: In this study 2514 male and female patients were included during a period of 5 years follow up. All patients have ambulatory blood pressure monitoring (ABPM) for at least 24h. We identified patients with treated and controlled BP according to current international guidelines (clinic BP, 140/90mmHg). Cardiovascular risk assessment was based on personal history, clinic BP values, as well as target organ damage evaluation. Masked uncontrolled hypertension (MUCH) was diagnosed in these patients if despite controlled clinic BP, the mean 24-h ABPM average remained elevated (24-h systolic BP ≥130mmHg and/or 24-h diastolic BP ≥80mmHg). Results: Patients had a mean age of 60.2+10 years, and the majority of them (94.6%) were followed by specialist physicians. Average clinic BP was 150.4+16/89.9+12 mmHg. About 70% of patients displayed a very high-risk profile. Ambulatory

  18. Determination of Extrapolation Distance with Measured Pressure Signatures from Two Low-Boom Models

    NASA Technical Reports Server (NTRS)

    Mack, Robert J.; Kuhn, Neil

    2004-01-01

    A study to determine a limiting distance to span ratio for the extrapolation of near-field pressure signatures is described and discussed. This study was to be done in two wind-tunnel facilities with two wind-tunnel models. At this time, only the first half had been completed, so the scope of this report is limited to the design of the models, and to an analysis of the first set of measured pressure signatures. The results from this analysis showed that the pressure signatures measured at separation distances of 2 to 5 span lengths did not show the desired low-boom shapes. However, there were indications that the pressure signature shapes were becoming 'flat-topped'. This trend toward a 'flat-top' pressure signatures shape was seen to be a gradual one at the distance ratios employed in this first series of wind-tunnel tests.

  19. The risk factors for elevated blood pressure and how to address cardiovascular risk factors: a review in paediatric populations.

    PubMed

    Monyeki, Kd; Kemper, Hcg

    2008-07-01

    This paper examines the epidemiology of hypertension and management strategies of cardiovascular diseases (CVDs) in paediatric populations in sub-Saharan Africa and other parts of the world in the 21st century. A computerized literature search was carried out using Medline, Evidence-Based Child Health (A Cochrane Review Journal), the Cochrane Library and Cochrane Child Health Field. A manual search in the African Journal for physical, health education, recreation and dance, the South African Journal for Research in Sports, Physical Education and Recreation and a few individuals in the area were requested to send some of their recent unpublished and published reports in the field. High prevalence rates and high odds ratios for high blood pressure (BP) were recorded in children aged 5-17 years. There is a need for health ministries to improve the public health sector so as to close the gap between the rich and the poor. Although personal and parental responsibility remain crucial, it also falls on the government to help control powerful environmental factors that are leading our children to premature ill-health and mortality. Equally, health professionals are increasingly recognized that they have a significant role to play in delivering medical treatment of hypertension in children.

  20. Galileo`s relativity principle, the concept of pressure, and complex characteristics, for the six-equation, one-pressure model

    SciTech Connect

    Makowitz, H.

    1992-10-01

    We have studied various formulations of the concept of pressure, in the context of the usual Six-Equation Model of thermal-hydraulics. A different concept of pressure, than the usual one, has been used. This new pressure concept is Galilean Invariant, and results for the One-Pressure Model with the same complex characteristic roots as the ``Basic III-Posed Model,`` discussed in the literature for the cases we have investigated. We have also examined several Two-Pressure formulations and shown that two pressures are a necessary but not sufficient condition for obtaining a Well-Posed system. Several counter examples are presented. We have shown that the standard theory is not Galilean Invariant and suggested that the origin of III-Posedness is due to our closure relationships. We also question whether the current theory can satisfy conservation principles for mass, energy, and momentum.

  1. Assessing risk factors for dental caries: a statistical modeling approach.

    PubMed

    Trottini, Mario; Bossù, Maurizio; Corridore, Denise; Ierardo, Gaetano; Luzzi, Valeria; Saccucci, Matteo; Polimeni, Antonella

    2015-01-01

    The problem of identifying potential determinants and predictors of dental caries is of key importance in caries research and it has received considerable attention in the scientific literature. From the methodological side, a broad range of statistical models is currently available to analyze dental caries indices (DMFT, dmfs, etc.). These models have been applied in several studies to investigate the impact of different risk factors on the cumulative severity of dental caries experience. However, in most of the cases (i) these studies focus on a very specific subset of risk factors; and (ii) in the statistical modeling only few candidate models are considered and model selection is at best only marginally addressed. As a result, our understanding of the robustness of the statistical inferences with respect to the choice of the model is very limited; the richness of the set of statistical models available for analysis in only marginally exploited; and inferences could be biased due the omission of potentially important confounding variables in the model's specification. In this paper we argue that these limitations can be overcome considering a general class of candidate models and carefully exploring the model space using standard model selection criteria and measures of global fit and predictive performance of the candidate models. Strengths and limitations of the proposed approach are illustrated with a real data set. In our illustration the model space contains more than 2.6 million models, which require inferences to be adjusted for 'optimism'.

  2. NASA Space Radiation Program Integrative Risk Model Toolkit

    NASA Technical Reports Server (NTRS)

    Kim, Myung-Hee Y.; Hu, Shaowen; Plante, Ianik; Ponomarev, Artem L.; Sandridge, Chris

    2015-01-01

    NASA Space Radiation Program Element scientists have been actively involved in development of an integrative risk models toolkit that includes models for acute radiation risk and organ dose projection (ARRBOD), NASA space radiation cancer risk projection (NSCR), hemocyte dose estimation (HemoDose), GCR event-based risk model code (GERMcode), and relativistic ion tracks (RITRACKS), NASA radiation track image (NASARTI), and the On-Line Tool for the Assessment of Radiation in Space (OLTARIS). This session will introduce the components of the risk toolkit with opportunity for hands on demonstrations. The brief descriptions of each tools are: ARRBOD for Organ dose projection and acute radiation risk calculation from exposure to solar particle event; NSCR for Projection of cancer risk from exposure to space radiation; HemoDose for retrospective dose estimation by using multi-type blood cell counts; GERMcode for basic physical and biophysical properties for an ion beam, and biophysical and radiobiological properties for a beam transport to the target in the NASA Space Radiation Laboratory beam line; RITRACKS for simulation of heavy ion and delta-ray track structure, radiation chemistry, DNA structure and DNA damage at the molecular scale; NASARTI for modeling of the effects of space radiation on human cells and tissue by incorporating a physical model of tracks, cell nucleus, and DNA damage foci with image segmentation for the automated count; and OLTARIS, an integrated tool set utilizing HZETRN (High Charge and Energy Transport) intended to help scientists and engineers study the effects of space radiation on shielding materials, electronics, and biological systems.

  3. Risk Stratification by Self-Measured Home Blood Pressure across Categories of Conventional Blood Pressure: A Participant-Level Meta-Analysis

    PubMed Central

    Asayama, Kei; Thijs, Lutgarde; Brguljan-Hitij, Jana; Niiranen, Teemu J.; Hozawa, Atsushi; Boggia, José; Aparicio, Lucas S.; Hara, Azusa; Johansson, Jouni K.; Ohkubo, Takayoshi; Tzourio, Christophe; Stergiou, George S.; Sandoya, Edgardo; Tsuji, Ichiro; Jula, Antti M.; Imai, Yutaka; Staessen, Jan A.

    2014-01-01

    Background The Global Burden of Diseases Study 2010 reported that hypertension is worldwide the leading risk factor for cardiovascular disease, causing 9.4 million deaths annually. We examined to what extent self-measurement of home blood pressure (HBP) refines risk stratification across increasing categories of conventional blood pressure (CBP). Methods and Findings This meta-analysis included 5,008 individuals randomly recruited from five populations (56.6% women; mean age, 57.1 y). All were not treated with antihypertensive drugs. In multivariable analyses, hazard ratios (HRs) associated with 10-mm Hg increases in systolic HBP were computed across CBP categories, using the following systolic/diastolic CBP thresholds (in mm Hg): optimal, <120/<80; normal, 120–129/80–84; high-normal, 130–139/85–89; mild hypertension, 140–159/90–99; and severe hypertension, ≥160/≥100. Over 8.3 y, 522 participants died, and 414, 225, and 194 had cardiovascular, cardiac, and cerebrovascular events, respectively. In participants with optimal or normal CBP, HRs for a composite cardiovascular end point associated with a 10-mm Hg higher systolic HBP were 1.28 (1.01–1.62) and 1.22 (1.00–1.49), respectively. At high-normal CBP and in mild hypertension, the HRs were 1.24 (1.03–1.49) and 1.20 (1.06–1.37), respectively, for all cardiovascular events and 1.33 (1.07–1.65) and 1.30 (1.09–1.56), respectively, for stroke. In severe hypertension, the HRs were not significant (p≥0.20). Among people with optimal, normal, and high-normal CBP, 67 (5.0%), 187 (18.4%), and 315 (30.3%), respectively, had masked hypertension (HBP≥130 mm Hg systolic or ≥85 mm Hg diastolic). Compared to true optimal CBP, masked hypertension was associated with a 2.3-fold (1.5–3.5) higher cardiovascular risk. A limitation was few data from low- and middle-income countries. Conclusions HBP substantially refines risk stratification at CBP levels assumed to carry no or only mildly increased

  4. Data Assimilation in an Ocean Model of the Mediterranean Sea Forced by the Atmospheric Pressure Gradient

    NASA Astrophysics Data System (ADS)

    Dobricic, Srdjan; Oddo, Paolo; Pinardi, Nadia

    2012-03-01

    Recently the atmospheric pressure gradient forcing has been implemented in the oceanographic model used in the Mediterranean Forecasting System data assimilation scheme. Experiments show that there is an impact on how the temperature and salinity is updated in the assimilation when the ocean model is forced by the atmospheric pressure gradient. It is, however, necessary to perform longer data assimilation experiments to quantify the impact on the quality of the MFS analyses of the state of the Mediterranean Sea.

  5. Life modeling of atmospheric and low pressure plasma-sprayed thermal-barrier coating

    NASA Technical Reports Server (NTRS)

    Miller, R. A.; Argarwal, P.; Duderstadt, E. C.

    1984-01-01

    The cycles-to-failure vs cycle duration data for three different thermal barrier coating systems, which consist of atmospheric pressure plasma-sprayed ZrO2-8 percent Y2O3 over similarly deposited or low pressure plasma sprayed Ni-base alloys, are presently analyzed by means of the Miller (1980) oxidation-based life model. Specimens were tested at 1100 C for heating cycle lengths of 1, 6, and 20 h, yielding results supporting the model's value.

  6. Influence and Modeling of Residual Stresses in Thick Walled Pressure Vessels with Through Holes

    DTIC Science & Technology

    2012-02-28

    Technical Report ARWSB-TR-12003 INFLUENCE AND MODELING OF RESIDUAL STRESSES IN THICK WALLED PRESSURE VESSELS WITH...DATE (DD-MM-YYYY) 28/02/2012 2. REPORT TYPE Technical Report 3. DATES COVERED (From - To) 4. TITLE AND SUBTITLE Influence and Modeling of...Residual Stresses in Thick Walled Pressure Vessels with Through Holes 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT

  7. High pressure thermal inactivation of Clostridium botulinum type E endospores – kinetic modeling and mechanistic insights

    PubMed Central

    Lenz, Christian A.; Reineke, Kai; Knorr, Dietrich; Vogel, Rudi F.

    2015-01-01

    Cold-tolerant, neurotoxigenic, endospore forming Clostridium (C.) botulinum type E belongs to the non-proteolytic physiological C. botulinum group II, is primarily associated with aquatic environments, and presents a safety risk for seafood. High pressure thermal (HPT) processing exploiting the synergistic effect of pressure and temperature can be used to inactivate bacterial endospores. We investigated the inactivation of C. botulinum type E spores by (near) isothermal HPT treatments at 300–1200 MPa at 30–75°C for 1 s to 10 min. The occurrence of heat and lysozyme susceptible spore fractions after such treatments was determined. The experimental data were modeled to obtain kinetic parameters and represented graphically by isoeffect lines. In contrast to findings for spores of other species and within the range of treatment parameters applied, zones of spore stabilization (lower inactivation than heat treatments alone), large heat susceptible (HPT-induced germinated) or lysozyme-dependently germinable (damaged coat layer) spore fractions were not detected. Inactivation followed first order kinetics. Dipicolinic acid release kinetics allowed for insights into possible inactivation mechanisms suggesting a (poorly effective) physiologic-like (similar to nutrient-induced) germination at ≤450 MPa/≤45°C and non-physiological germination at >500 MPa/>60–70°C. Results of this study support the existence of some commonalities in the HPT inactivation mechanism of C. botulinum type E spores and Bacillus spores although both organisms have significantly different HPT resistance properties. The information presented here contributes to closing the gap in knowledge regarding the HPT inactivation of spore formers relevant to food safety and may help industrial implementation of HPT processing. The markedly lower HPT resistance of C. botulinum type E spores compared with the resistance of spores from other C. botulinum types could allow for the implementation of

  8. Evaluation of Progressive Failure Analysis and Modeling of Impact Damage in Composite Pressure Vessels

    NASA Technical Reports Server (NTRS)

    Sanchez, Christopher M.

    2011-01-01

    NASA White Sands Test Facility (WSTF) is leading an evaluation effort in advanced destructive and nondestructive testing of composite pressure vessels and structures. WSTF is using progressive finite element analysis methods for test design and for confirmation of composite pressure vessel performance. Using composite finite element analysis models and failure theories tested in the World-Wide Failure Exercise, WSTF is able to estimate the static strength of composite pressure vessels. Additionally, test and evaluation on composites that have been impact damaged is in progress so that models can be developed to estimate damage tolerance and the degradation in static strength.

  9. Modelling oxygen self-diffusion in UO2 under pressure

    SciTech Connect

    Cooper, Michael William D.; Grimes, R. W.; Fitzpatrick, M. E.; Chroneos, A.

    2015-10-22

    Access to values for oxygen self-diffusion over a range of temperatures and pressures in UO2 is important to nuclear fuel applications. Here, elastic and expansivity data are used in the framework of a thermodynamic model, the cBΩ model, to derive the oxygen self-diffusion coefficient in UO2 over a range of pressures (0–10 GPa) and temperatures (300–1900 K). Furthermore, the significant reduction in oxygen self-diffusion as a function of increasing hydrostatic pressure, and the associated increase in activation energy, is identified.

  10. A damage model for volcanic edifices: Implications for edifice strength, magma pressure, and eruptive processes

    NASA Astrophysics Data System (ADS)

    Carrier, Aurore; Got, Jean-Luc; Peltier, Aline; Ferrazzini, Valérie; Staudacher, Thomas; Kowalski, Philippe; Boissier, Patrice

    2015-01-01

    Monitoring of large basaltic volcanoes, such as Piton de la Fournaise (La Réunion Island, France), has revealed preeruptive accelerations in surface displacements and seismicity rate over a period of between 1 h and several weeks before magma reaches the surface. Such eruptions are attributed to ruptures of pressurized magma reservoirs. Elastic models used to describe surface deformation would assume that accelerations in surface deformation are due to increases in reservoir pressure. This assumption requires changes in magma or pressure conditions at the base of the magma feeding system that are unrealistic over the observed timescale. Another possible cause for these accelerations is magma pressure in the reservoir weakening the volcanic edifice. In the present study, we modeled such weakening by progressive damage to an initially elastic edifice. We used an incremental damage model, with seismicity as a damage variable with daily increments. Elastic moduli decrease linearly with each damage increment. Applied to an initially elastic edifice with constant pressure at the base of the system, this damage model reproduces surface displacement accelerations quite well when damage is sufficient. Process dynamics is controlled by the damage parameter, taken as the ratio between the incremental rupture surface and the surface to be ruptured. In this case, edifice strength and magma reservoir pressure decrease with decreasing elastic moduli, whereas surface displacement accelerates. We discuss the consequences of pressure decreases in magma reservoirs.

  11. Tutorial: Parallel Computing of Simulation Models for Risk Analysis.

    PubMed

    Reilly, Allison C; Staid, Andrea; Gao, Michael; Guikema, Seth D

    2016-10-01

    Simulation models are widely used in risk analysis to study the effects of uncertainties on outcomes of interest in complex problems. Often, these models are computationally complex and time consuming to run. This latter point may be at odds with time-sensitive evaluations or may limit the number of parameters that are considered. In this article, we give an introductory tutorial focused on parallelizing simulation code to better leverage modern computing hardware, enabling risk analysts to better utilize simulation-based methods for quantifying uncertainty in practice. This article is aimed primarily at risk analysts who use simulation methods but do not yet utilize parallelization to decrease the computational burden of these models. The discussion is focused on conceptual aspects of embarrassingly parallel computer code and software considerations. Two complementary examples are shown using the languages MATLAB and R. A brief discussion of hardware considerations is located in the Appendix.

  12. The use of ecosystem models in risk assessment

    SciTech Connect

    Starodub, M.E.; Miller, P.A.; Willes, R.F.

    1994-12-31

    Ecosystem models, when used in conjunction with available environmental effects monitoring data enable informed decisions regarding actions that should be taken to manage ecological risks from areas of localized chemical loadings and accumulation. These models provide quantitative estimates of chemical concentrations in various environmental media. The reliable application of these models as predictive tools for environmental assessment requires a thorough understanding of the theory and mathematical relationships described by the models and demands rigorous validation of input data and model results with field and laboratory data. Food chain model selection should be based on the ability to best simulate the interactions of the food web and processes governing the transfer of chemicals from the dissolved and particulate phase to various trophic levels for the site in question. This requires that the user be familiar with the theories on which these models are based, and be aware of the merits and short comings of each prior to attempting to model food chain accumulation. Questions to be asked include: are all potential exposure pathways addressed? are omitted pathways critical to the risk assessment process? is the model flexible? To answer these questions one must consider the, chemical(s) of concern, site-specific ecosystem characteristics, risk assessment receptor (aquatic, wildlife, human) dietary habits, influence of effluent characteristics on food chain dynamics.

  13. Physics-based Entry, Descent and Landing Risk Model

    NASA Technical Reports Server (NTRS)

    Gee, Ken; Huynh, Loc C.; Manning, Ted

    2014-01-01

    A physics-based risk model was developed to assess the risk associated with thermal protection system failures during the entry, descent and landing phase of a manned spacecraft mission. In the model, entry trajectories were computed using a three-degree-of-freedom trajectory tool, the aerothermodynamic heating environment was computed using an engineering-level computational tool and the thermal response of the TPS material was modeled using a one-dimensional thermal response tool. The model was capable of modeling the effect of micrometeoroid and orbital debris impact damage on the TPS thermal response. A Monte Carlo analysis was used to determine the effects of uncertainties in the vehicle state at Entry Interface, aerothermodynamic heating and material properties on the performance of the TPS design. The failure criterion was set as a temperature limit at the bondline between the TPS and the underlying structure. Both direct computation and response surface approaches were used to compute the risk. The model was applied to a generic manned space capsule design. The effect of material property uncertainty and MMOD damage on risk of failure were analyzed. A comparison of the direct computation and response surface approach was undertaken.

  14. Model helicopter rotor high-speed impulsive noise: Measured acoustics and blade pressures

    NASA Technical Reports Server (NTRS)

    Boxwell, D. A.; Schmitz, F. H.; Splettstoesser, W. R.; Schultz, K. J.

    1983-01-01

    A 1/17-scale research model of the AH-1 series helicopter main rotor was tested. Model-rotor acoustic and simultaneous blade pressure data were recorded at high speeds where full-scale helicopter high-speed impulsive noise levels are known to be dominant. Model-rotor measurements of the peak acoustic pressure levels, waveform shapes, and directively patterns are directly compared with full-scale investigations, using an equivalent in-flight technique. Model acoustic data are shown to scale remarkably well in shape and in amplitude with full-scale results. Model rotor-blade pressures are presented for rotor operating conditions both with and without shock-like discontinuities in the radiated acoustic waveform. Acoustically, both model and full-scale measurements support current evidence that above certain high subsonic advancing-tip Mach numbers, local shock waves that exist on the rotor blades ""delocalize'' and radiate to the acoustic far-field.

  15. Improved lattice Boltzmann model for multi-component diffusion flow with large pressure difference

    NASA Astrophysics Data System (ADS)

    Liu, Fu-Min; Wang, An-Lin; Qiu, Ruo-Fan; Jiang, Tao

    2016-05-01

    The pseudopotential lattice Boltzmann model has been widely used to solve multi-phase and multi-component flow problems. However, original pseudopotential model cannot be used in simulating diffusion flow with large pressure difference because of its limitation. In this paper, we incorporate pseudopotential model with a new form of effective mass to solve this problem based on the relationship between pressure difference and effective mass. The improved model is verified through Laplace’s law and binary immiscible Poiseuille flow. By simulating pipeline binary diffusion flow and two-inlet binary cavity jet flow, we show that the improved model can achieve larger pressure difference than pseudopotential model with traditional effective mass forms.

  16. Evaluating biomarkers to model cancer risk post cosmic ray exposure.

    PubMed

    Sridharan, Deepa M; Asaithamby, Aroumougame; Blattnig, Steve R; Costes, Sylvain V; Doetsch, Paul W; Dynan, William S; Hahnfeldt, Philip; Hlatky, Lynn; Kidane, Yared; Kronenberg, Amy; Naidu, Mamta D; Peterson, Leif E; Plante, Ianik; Ponomarev, Artem L; Saha, Janapriya; Snijders, Antoine M; Srinivasan, Kalayarasan; Tang, Jonathan; Werner, Erica; Pluth, Janice M

    2016-06-01

    Robust predictive models are essential to manage the risk of radiation-induced carcinogenesis. Chronic exposure to cosmic rays in the context of the complex deep space environment may place astronauts at high cancer risk. To estimate this risk, it is critical to understand how radiation-induced cellular stress impacts cell fate decisions and how this in turn alters the risk of carcinogenesis. Exposure to the heavy ion component of cosmic rays triggers a multitude of cellular changes, depending on the rate of exposure, the type of damage incurred and individual susceptibility. Heterogeneity in dose, dose rate, radiation quality, energy and particle flux contribute to the complexity of risk assessment. To unravel the impact of each of these factors, it is critical to identify sensitive biomarkers that can serve as inputs for robust modeling of individual risk of cancer or other long-term health consequences of exposure. Limitations in sensitivity of biomarkers to dose and dose rate, and the complexity of longitudinal monitoring, are some of the factors that increase uncertainties in the output from risk prediction models. Here, we critically evaluate candidate early and late biomarkers of radiation exposure and discuss their usefulness in predicting cell fate decisions. Some of the biomarkers we have reviewed include complex clustered DNA damage, persistent DNA repair foci, reactive oxygen species, chromosome aberrations and inflammation. Other biomarkers discussed, often assayed for at longer points post exposure, include mutations, chromosome