Blood pressure-lowering treatment strategies based on cardiovascular risk versus blood pressure: A meta-analysis of individual participant data

PubMed Central

Karmali, Kunal N.; Lloyd-Jones, Donald M.; Zanchetti, Alberto; Jackson, Rodney; Woodward, Mark; Neal, Bruce C.; Berge, Eivind; Teo, Koon; Davis, Barry R.; Pepine, Carl

2018-01-01

Background Clinical practice guidelines have traditionally recommended blood pressure treatment based primarily on blood pressure thresholds. In contrast, using predicted cardiovascular risk has been advocated as a more effective strategy to guide treatment decisions for cardiovascular disease (CVD) prevention. We aimed to compare outcomes from a blood pressure-lowering treatment strategy based on predicted cardiovascular risk with one based on systolic blood pressure (SBP) level. Methods and findings We used individual participant data from the Blood Pressure Lowering Treatment Trialists’ Collaboration (BPLTTC) from 1995 to 2013. Trials randomly assigned participants to either blood pressure-lowering drugs versus placebo or more intensive versus less intensive blood pressure-lowering regimens. We estimated 5-y risk of CVD events using a multivariable Weibull model previously developed in this dataset. We compared the two strategies at specific SBP thresholds and across the spectrum of risk and blood pressure levels studied in BPLTTC trials. The primary outcome was number of CVD events avoided per persons treated. We included data from 11 trials (47,872 participants). During a median of 4.0 y of follow-up, 3,566 participants (7.5%) experienced a major cardiovascular event. Areas under the curve comparing the two treatment strategies throughout the range of possible thresholds for CVD risk and SBP demonstrated that, on average, a greater number of CVD events would be avoided for a given number of persons treated with the CVD risk strategy compared with the SBP strategy (area under the curve 0.71 [95% confidence interval (CI) 0.70–0.72] for the CVD risk strategy versus 0.54 [95% CI 0.53–0.55] for the SBP strategy). Compared with treating everyone with SBP ≥ 150 mmHg, a CVD risk strategy would require treatment of 29% (95% CI 26%–31%) fewer persons to prevent the same number of events or would prevent 16% (95% CI 14%–18%) more events for the same number of

Decision making under time pressure, modeled in a prospect theory framework.

PubMed

Young, Diana L; Goodie, Adam S; Hall, Daniel B; Wu, Eric

2012-07-01

The current research examines the effects of time pressure on decision behavior based on a prospect theory framework. In Experiments 1 and 2, participants estimated certainty equivalents for binary gains-only bets in the presence or absence of time pressure. In Experiment 3, participants assessed comparable bets that were framed as losses. Data were modeled to establish psychological mechanisms underlying decision behavior. In Experiments 1 and 2, time pressure led to increased risk attractiveness, but no significant differences emerged in either probability discriminability or outcome utility. In Experiment 3, time pressure reduced probability discriminability, which was coupled with severe risk-seeking behavior for both conditions in the domain of losses. No significant effects of control over outcomes were observed. Results provide qualified support for theories that suggest increased risk-seeking for gains under time pressure.

Personalized modeling for real-time pressure ulcer prevention in sitting posture.

PubMed

Luboz, Vincent; Bailet, Mathieu; Boichon Grivot, Christelle; Rochette, Michel; Diot, Bruno; Bucki, Marek; Payan, Yohan

2018-02-01

Ischial pressure ulcer is an important risk for every paraplegic person and a major public health issue. Pressure ulcers appear following excessive compression of buttock's soft tissues by bony structures, and particularly in ischial and sacral bones. Current prevention techniques are mainly based on daily skin inspection to spot red patches or injuries. Nevertheless, most pressure ulcers occur internally and are difficult to detect early. Estimating internal strains within soft tissues could help to evaluate the risk of pressure ulcer. A subject-specific biomechanical model could be used to assess internal strains from measured skin surface pressures. However, a realistic 3D non-linear Finite Element buttock model, with different layers of tissue materials for skin, fat and muscles, requires somewhere between minutes and hours to compute, therefore forbidding its use in a real-time daily prevention context. In this article, we propose to optimize these computations by using a reduced order modeling technique (ROM) based on proper orthogonal decompositions of the pressure and strain fields coupled with a machine learning method. ROM allows strains to be evaluated inside the model interactively (i.e. in less than a second) for any pressure field measured below the buttocks. In our case, with only 19 modes of variation of pressure patterns, an error divergence of one percent is observed compared to the full scale simulation for evaluating the strain field. This reduced model could therefore be the first step towards interactive pressure ulcer prevention in a daily set-up. Copyright © 2017 Tissue Viability Society. Published by Elsevier Ltd. All rights reserved.

Decision making under time pressure, modeled in a prospect theory framework

PubMed Central

Young, Diana L.; Goodie, Adam S.; Hall, Daniel B.; Wu, Eric

2012-01-01

The current research examines the effects of time pressure on decision behavior based on a prospect theory framework. In Experiments 1 and 2, participants estimated certainty equivalents for binary gains-only bets in the presence or absence of time pressure. In Experiment 3, participants assessed comparable bets that were framed as losses. Data were modeled to establish psychological mechanisms underlying decision behavior. In Experiments 1 and 2, time pressure led to increased risk attractiveness, but no significant differences emerged in either probability discriminability or outcome utility. In Experiment 3, time pressure reduced probability discriminability, which was coupled with severe risk-seeking behavior for both conditions in the domain of losses. No significant effects of control over outcomes were observed. Results provide qualified support for theories that suggest increased risk-seeking for gains under time pressure. PMID:22711977

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.

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

PubMed Central

Ntalla, Ioanna; Surendran, Praveen; Liu, Chunyu; Cook, James P; Kraja, Aldi T; Drenos, Fotios; Loh, Marie; Verweij, Niek; Marten, Jonathan; Karaman, Ibrahim; Segura Lepe, Marcelo P; 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

2017-01-01

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. Combined 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. PMID:28135244

Developing a pressure ulcer risk factor minimum data set and risk assessment framework.

PubMed

Coleman, Susanne; Nelson, E Andrea; Keen, Justin; Wilson, Lyn; McGinnis, Elizabeth; Dealey, Carol; Stubbs, Nikki; Muir, Delia; Farrin, Amanda; Dowding, Dawn; Schols, Jos M G A; Cuddigan, Janet; Berlowitz, Dan; Jude, Edward; Vowden, Peter; Bader, Dan L; Gefen, Amit; Oomens, Cees W J; Schoonhoven, Lisette; Nixon, Jane

2014-10-01

To agree a draft pressure ulcer risk factor Minimum Data Set to underpin the development of a new evidenced-based Risk Assessment Framework. A recent systematic review identified the need for a pressure ulcer risk factor Minimum Data Set and development and validation of an evidenced-based pressure ulcer Risk Assessment Framework. This was undertaken through the Pressure UlceR Programme Of reSEarch (RP-PG-0407-10056), funded by the National Institute for Health Research and incorporates five phases. This article reports phase two, a consensus study. Consensus study. A modified nominal group technique based on the Research and Development/University of California at Los Angeles appropriateness method. This incorporated an expert group, review of the evidence and the views of a Patient and Public Involvement service user group. Data were collected December 2010-December 2011. The risk factors and assessment items of the Minimum Data Set (including immobility, pressure ulcer and skin status, perfusion, diabetes, skin moisture, sensory perception and nutrition) were agreed. In addition, a draft Risk Assessment Framework incorporating all Minimum Data Set items was developed, comprising a two stage assessment process (screening and detailed full assessment) and decision pathways. The draft Risk Assessment Framework will undergo further design and pre-testing with clinical nurses to assess and improve its usability. It will then be evaluated in clinical practice to assess its validity and reliability. The Minimum Data Set could be used in future for large scale risk factor studies informing refinement of the Risk Assessment Framework. © 2014 The Authors. Journal of Advanced Nursing Published by John Wiley & Sons Ltd.

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.

Incidence and risk factors associated with pressure ulcers among patients with HIV infection.

PubMed

Nicastri, Emanuele; Viale, Pierluigi; Lyder, Courtney H; Cristini, Francesco; Martini, Lorena; Preziosi, Gianni; Dodi, Ferdinando; Irato, Laura; Pan, Angelo; Petrosillo, Nicola

2004-06-01

To assess the incidence of and risk factors for pressure ulcers among patients with advanced human immunodeficiency virus type 1 (HIV-1) infection. Multicenter trial that included 1258 consecutive patients infected with HIV-1 who had 1815 admissions to 16 acute care infectious disease units in Italy. Data were collected for demographic, clinical, immunologic, and virologic parameters. The chi-square test was used to compare categorical variables, and the Student t test was used for continuous variables. Univariate analysis was performed to examine possible risk factors for pressure ulcers by computing odds ratios; a multiple logistic regression model was used to obtain adjusted estimates of odds ratios while accounting for all possible risk factors. The incidence of pressure ulcers was 2.31 per 100 admissions, 3.33 per 100 patients, and 1.06 per 1000 patient days. All stages of pressure ulcers were represented in the sample: 7 Stage I (15.9%), 24 Stage II (54.5%), 8 Stage III (18.2%), and 5 Stage IV (11.4%). Multivariate analyses showed that being female, length of hospitalization, and clinical markers of HIV infection were independently associated with pressure ulcers. Mortality rates were 50% among patients with pressure ulcers and 7.2% among patients without pressure ulcers (P <.0001), with an attributable mortality rate of 42.8% and an odds ratio of 12.96 (95% confidence interval 6.99-24.22). A higher incidence of pressure ulcers was found in patients infected with HIV-1 when compared with noninfected patients. Because a longer hospitalization may increase the risk of developing a pressure ulcer, practitioners should be aware of the clinical conditions that may prolong a patient's hospital stay. Aggressive preventive strategies should be implemented to decrease the complications associated with pressure ulcers among patients infected with HIV-1.

What patient characteristics guide nurses' clinical judgement on pressure ulcer risk? A mixed methods study.

PubMed

Balzer, K; Kremer, L; Junghans, A; Halfens, R J G; Dassen, T; Kottner, J

2014-05-01

Nurses' clinical judgement plays a vital role in pressure ulcer risk assessment, but evidence is lacking which patient characteristics are important for nurses' perception of patients' risk exposure. To explore which patient characteristics nurses employ when assessing pressure ulcer risk without use of a risk assessment scale. Mixed methods design triangulating observational data from the control group of a quasi-experimental trial and data from semi-structured interviews with nurses. Two traumatological wards at a university hospital. Quantitative data: A consecutive sample of 106 patients matching the eligibility criteria (age ≥ 18 years, no pressure ulcers category ≥ 2 at admission and ≥ 5 days expected length of stay). Qualitative data: A purposive sample of 16 nurses. Quantitative data: Predictor variables for pressure ulcer risk were measured by study assistants at the bedside each second day. Concurrently, nurses documented their clinical judgement on patients' pressure ulcer risk by means of a 4-step global judgement scale. Bivariate correlations between predictor variables and nurses' risk estimates were established. Qualitative data: In interviews, nurses were asked to assess fictitious patients' pressure ulcer risk and to justify their risk estimates. Patient characteristics perceived as relevant for nurses' judements were thematically clustered. Triangulation: Firstly, predictors of nurses' risk estimates identified in bivariate analysis were cross-mapped with interview findings. Secondly, three models to predict nurses' risk estimates underwent multiple linear regression analysis. Nurses consider multiple patient characteristics for pressure ulcer risk assessment, but regard some conditions more important than others. Triangulation showed that these are measures reflecting patients' exposure to pressure or overall care dependency. Qualitative data furthermore indicate that nurses are likely to trade off risk-enhancing conditions against

[Development of the nursing diagnosis risk for pressure ulcer].

PubMed

Santos, Cássia Teixeira Dos; Almeida, Miriam de Abreu; Oliveira, Magáli Costa; Victor, Marco Antônio de Goes; Lucena, Amália de Fátima

2015-06-01

The study objective was to develop the definition and compile the risk factors for a new Nursing Diagnosis entitled "Risk for pressure ulcer". The process was guided using the research question, "What are the risk factors for development of a PU and what is its definition?" An integrative literature review was conducted of articles published in Portuguese, English or Spanish from 2002 to 2012 and indexed on the Lilacs/SCIELO, MEDLINE/PubMed Central and Web of Science databases. The final sample comprised 21 articles that provided answers to the research question. These articles were analyzed and summarized in charts. A definition was constructed and 19 risk factors were selected for the new nursing diagnosis, "Risk for pressure ulcer". Identification and definition of the components of the new nursing diagnosis should aid nurses to prevent pressure ulcer events.

Prevention of pressure sores by identifying patients at risk.

PubMed Central

Andersen, K E; Jensen, O; Kvorning, S A; Bach, E

1982-01-01

The risk of pressure sores developing in patients admitted with acute conditions was assessed by a simple risk score system based on age, reduced mobility, incontinence, pronounced emaciation, redness over bony prominences, unconsciousness, dehydration, and paralysis in a prospective clinical study. During seven months in 1977, 600 of 3571 patients were classified as at risk. Of these 35 (5.8%) developed sores compared with five (0.2%) of those not at risk. The results of this study compared with those over the same period in 1976 show that close observation of at-risk patients and early detection of pressure sores prevents their development. PMID:6803980

Modeling Oxygen Prebreathe Protocols for Exploration Extravehicular Activities Using Variable Pressure Suits

NASA Technical Reports Server (NTRS)

Abercromby, Andrew F. J.; Conkin, Johnny; Gernhardt, Michael L.

2017-01-01

Exploration missions are expected to use variable pressure extravehicular activity (EVA) spacesuits as well as a spacecraft "exploration atmosphere" of 56.5 kPa (8.2 psia), 34% O2, both of which provide the possibility of reducing the oxygen prebreathe times necessary to reduce decompression sickness (DCS) risk. Previous modeling work predicted 8.4% DCS risk for an EVA beginning at the exploration atmosphere, followed by 15 minutes of in-suit O2 prebreathe, and 6 hours of EVA at 29.6 kPa (4.3 psia). In this study we model notional prebreathe protocols for a variable pressure suit where the exploration atmosphere is unavailable.

A Nurse-Initiated Perioperative Pressure Injury Risk Assessment and Prevention Protocol.

PubMed

Meehan, Anita J; Beinlich, Nancy R; Hammonds, Tracy L

2016-12-01

Pressure injuries negatively affect patients physically, emotionally, and economically. Studies report that pressure injuries occur in 69% of inpatients who have undergone a surgical procedure while hospitalized. In 2012, we created a nurse-initiated, perioperative pressure injury risk assessment measure for our midwestern, urban, adult teaching hospital. We retrospectively applied the risk assessment to a random sample of 350 surgical patients which validated the measure. The prospective use of the risk assessment and prevention measures in 350 surgical patients resulted in a 60% reduction in pressure injuries compared with the retrospective group. Our findings support the use of a multipronged approach for the prevention of health care-associated pressure injuries in the surgical population, which includes assessment of risk, implementation of evidence-based prevention interventions for at-risk patients, and continuation of prevention beyond the perioperative setting to the nursing care unit. Copyright © 2016 AORN, Inc. Published by Elsevier Inc. All rights reserved.

Use of Repeated Blood Pressure and Cholesterol Measurements to Improve Cardiovascular Disease Risk Prediction: An Individual-Participant-Data Meta-Analysis

PubMed Central

Barrett, Jessica; Pennells, Lisa; Sweeting, Michael; Willeit, Peter; Di Angelantonio, Emanuele; Gudnason, Vilmundur; Nordestgaard, Børge G.; Psaty, Bruce M; Goldbourt, Uri; Best, Lyle G; Assmann, Gerd; Salonen, Jukka T; Nietert, Paul J; Verschuren, W. M. Monique; Brunner, Eric J; Kronmal, Richard A; Salomaa, Veikko; Bakker, Stephan J L; Dagenais, Gilles R; Sato, Shinichi; Jansson, Jan-Håkan; Willeit, Johann; Onat, Altan; de la Cámara, Agustin Gómez; Roussel, Ronan; Völzke, Henry; Dankner, Rachel; Tipping, Robert W; Meade, Tom W; Donfrancesco, Chiara; Kuller, Lewis H; Peters, Annette; Gallacher, John; Kromhout, Daan; Iso, Hiroyasu; Knuiman, Matthew; Casiglia, Edoardo; Kavousi, Maryam; Palmieri, Luigi; Sundström, Johan; Davis, Barry R; Njølstad, Inger; Couper, David; Danesh, John; Thompson, Simon G; Wood, Angela

2017-01-01

Abstract The added value of incorporating information from repeated blood pressure and cholesterol measurements to predict cardiovascular disease (CVD) risk has not been rigorously assessed. We used data on 191,445 adults from the Emerging Risk Factors Collaboration (38 cohorts from 17 countries with data encompassing 1962–2014) with more than 1 million measurements of systolic blood pressure, total cholesterol, and high-density lipoprotein cholesterol. Over a median 12 years of follow-up, 21,170 CVD events occurred. Risk prediction models using cumulative mean values of repeated measurements and summary measures from longitudinal modeling of the repeated measurements were compared with models using measurements from a single time point. Risk discrimination (C-index) and net reclassification were calculated, and changes in C-indices were meta-analyzed across studies. Compared with the single-time-point model, the cumulative means and longitudinal models increased the C-index by 0.0040 (95% confidence interval (CI): 0.0023, 0.0057) and 0.0023 (95% CI: 0.0005, 0.0042), respectively. Reclassification was also improved in both models; compared with the single-time-point model, overall net reclassification improvements were 0.0369 (95% CI: 0.0303, 0.0436) for the cumulative-means model and 0.0177 (95% CI: 0.0110, 0.0243) for the longitudinal model. In conclusion, incorporating repeated measurements of blood pressure and cholesterol into CVD risk prediction models slightly improves risk prediction. PMID:28549073

The evaluation of daily living activities, pressure sores and risk factors.

PubMed

Aydın, Gökçen; Mucuk, Salime

2015-01-01

This study was conducted to assess daily living activities, pressure sores and risk factors. This was a descriptive study. The study was conducted at a rehabilitation center with 188 individuals participating in the study. Data were collected with a questionnaire form, Activities of Daily Living Scale (ADLS), Instrumental Activities of Daily Living Scale (IADLS) and Braden Risk Assessment Scale (BRAS). Among the participants, 48.9% were dependent according to activities of daily living and 71.8% were dependent on instrumental activities of daily living. It was noted that 4.8% had pressure sores and 38.8% were at high risk. A strong and positive correlation was found among ADLS, IADLS, and BRAS scores (p < .001). Participants who had a low body mass index, had lived at the rehabilitation center for a long time, and were fed on regime 1 or 2, had a higher risk of developing pressure sores (p < .001). Individuals who were dependent according to ADLS and IADLS were at increased risk for the development of pressure sores. Individuals who are treated at rehabilitation centers should be periodically assessed in terms of risk. Pressure sore development can be prevented with appropriate nursing interventions. To reduce the risk of developing pressure sores, nurses should describe the individual's degree of dependency according to ADLS and IADLS and initiate preventive nursing care. © 2014 Association of Rehabilitation Nurses.

Blood Pressure, Emotional Dampening, and Risk Behavior: Implications for Hypertension Development.

PubMed

McCubbin, James A; Nathan, Aaron; Hibdon, Melissa A; Castillo, Anastasia M; Graham, Jack G; Switzer, Fred S

2018-05-07

Elevated resting blood pressure (BP) is associated with risk for hypertension and emotional dampening, including reduced responses to emotionally meaningful stimuli. Perception of threat is a critical motivator in avoidance of risky health-damaging behavior. We hypothesize that BP-associated dampening of threat appraisal may increase risk-taking behavior. We measured resting BP, perception of affect, and risk behavior in 92 healthy, women (n=49) and men (n=43) recruited from university students and staff, and members of the surrounding community. Mean age +/- standard deviation for the sample was 21.5 +/- 4.3 year. Blood pressure was measured using an automated blood pressure monitor, and risk behavior was assessed with a modified National College Health Risk Behavior Survey. We also measured recognition of affect using the Perception of Affect Task (PAT). Risk-taking behavior was positively correlated with both systolic (SBP; r(89)=.278, p=.008) and diastolic blood pressure (DBP; r(89)=.309, p<.003). Regression analysis indicated that the association between risk-taking behavior and blood pressure was not mediated by PAT scores. Results show that persons with higher resting BP levels report increased risk-taking behavior. PAT scores, while correlated with SBP, did not mediate the relationship between BP and risk. The relationship between BP and risk behavior reflects the potential involvement of CNS regulation of both BP and emotional responsivity, and its relationship to health damaging behavior and risk for hypertension.

Measuring static seated pressure distributions and risk for skin pressure ulceration in ice sledge hockey players.

PubMed

Darrah, Shaun D; Dicianno, Brad E; Berthold, Justin; McCoy, Andrew; Haas, Matthew; Cooper, Rory A

2016-01-01

To determine whether sledge hockey players with physical disability have higher average seated pressures compared to non-disabled controls. Fifteen age-matched controls without physical disability and 15 experimental participants with physical disability were studied using a pressure mapping device to determine risk for skin pressure ulceration and the impact of cushioning and knee angle positioning on seated pressure distributions. Regardless of participant group, cushioning, or knee angle, average seated pressures exceeded clinically acceptable seated pressures. Controls had significantly higher average seated pressures than the disability group when knees were flexed, both with the cushion (p = 0.013) and without (p = 0.015). Knee extension showed significantly lower average pressures in controls, both with the cushion (p < 0.001) and without (p < 0.001). Placement of the cushion resulted in significantly lower average pressure in controls when knees were extended (p = 0.024) but not when flexed (p = 0.248). Placement of the cushion resulted in no difference in pressure (p = 0.443) in the disability group. Pressures recorded indicate high risk for skin ulceration. Cushioning was effective only in the control group with knees extended. That knee extension significantly lowered average seated pressures is important, as many sledge hockey players utilize positioning with larger knee flexion angles. Implications for Rehabilitation Ice sledge hockey is a fast growing adaptive sport. Adaptive sports have been associated with several positive improvements in overall health and quality of life, though may be putting players at risk for skin ulceration. Measured static seated pressure in sledges greatly exceeds current clinically accepted clinical guidelines. With modern improvements in wheelchair pressure relief/cushioning there are potential methods for improvement of elevated seated pressure in ice hockey sledges.

[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.

Differential influence of distinct components of increased blood pressure on cardiovascular outcomes: from the atherosclerosis risk in communities study.

PubMed

Cheng, Susan; Gupta, Deepak K; Claggett, Brian; Sharrett, A Richey; Shah, Amil M; Skali, Hicham; Takeuchi, Madoka; Ni, Hanyu; Solomon, Scott D

2013-09-01

Elevation in blood pressure (BP) increases risk for all cardiovascular events. Nevertheless, the extent to which different indices of BP elevation may be associated to varying degrees with different cardiovascular outcomes remains unclear. We studied 13340 participants (aged 54 ± 6 years, 56% women and 27% black) of the Atherosclerosis Risk in Communities Study who were free of baseline cardiovascular disease. We used Cox proportional hazards models to compare the relative contributions of systolic BP, diastolic BP, pulse pressure, and mean arterial pressure to risk for coronary heart disease, heart failure, stroke, and all-cause mortality. For each multivariable-adjusted model, the largest area under the receiver-operating curve (AUC) and smallest -2 log-likelihood values were used to identify BP measures with the greatest contribution to risk prediction for each outcome. A total of 2095 coronary heart disease events, 1669 heart failure events, 771 stroke events, and 3016 deaths occurred during 18 ± 5 years of follow-up. In multivariable analyses adjusting for traditional cardiovascular risk factors, the BP measures with the greatest risk contributions were the following: systolic BP for coronary heart disease (AUC=0.74); pulse pressure for heart failure (AUC=0.79); systolic BP for stroke (AUC=0.74); and pulse pressure for all-cause mortality (AUC=0.74). With few exceptions, results were similar in analyses stratified by age, sex, and race. Our data indicate that distinct BP components contribute variably to risk for different cardiovascular outcomes.

Pressure Ulcer Risk in the Incontinent Patient: Analysis of Incontinence and Hospital-Acquired Pressure Ulcers From the International Pressure Ulcer Prevalence™ Survey.

PubMed

Lachenbruch, Charlie; Ribble, David; Emmons, Kirsten; VanGilder, Catherine

2016-01-01

To measure the prevalence of incontinence in the 2013-2014 International Pressure Ulcer Prevalence (IPUP) surveys and determine the relative risk of developing a facility-acquired pressure ulcers (FAPUs) by stage and by Braden Scale score groupings. The IPUP survey is an observational, cross-sectional cohort database designed to determine the frequency and severity of pressure ulcers in various populations. The survey includes acute care (91.4%), long-term acute care (1.7%), rehabilitation patients (1.7%) and long-term care residents (5.2%). Geographic distribution included 182,832 patients in the United States, 22,282 patients in Canada, and the rest of the world, primarily in Europe and the Middle East. We analyzed data from the 2013 and 2014 IPUP surveys to better understand the relationship between incontinence and the frequency and severity of FAPUs. The IPUP survey is an annual voluntary survey of patients who are hospitalized or who reside in long-term care facilities. Data were collected over a 24-hour period within each participating facility. Data collection included limited demographics, presence and stage of pressure ulcers, and pressure ulcer risk assessment score (Braden Scale for Pressure Sore Risk, Braden Q, Norton, Waterlow, and others). In addition, data were collected on pertinent pressure ulcer risk factors including the number of linen layers, use of a pressure redistributing surface, adherence to repositioning schedule, and whether moisture management was provided in the last 24 hours. We aggregated data by urinary, urinary catheter, fecal, fecal management system, double (urinary and fecal), and ostomy incontinence category. If patients were managed by indwelling urinary catheter or fecal management systems, they were considered incontinent in this analysis. In order to analyze ulcers likely to be affected by incontinence, we defined a subset of ulcers as Relevant Pressure Ulcers, which are ulcers that are facility-acquired, non

[Pressure ulcer prevention--evaluation of awarness in families of patients at risk].

PubMed

Kwiczala-Szydłowska, Seweryna; Skalska, Anna; Grodzicki, Tomasz

2005-01-01

Widespread use of risk assessing scales and standards in health care of chronically ill patients resulted in improvement of pressure ulcer prevention and treatment in institutional care. However many bed-ridden patients depend on awareness and preparation of families and caregivers, who provide home care after discharge from the hospital. The aim of this study was to evaluate the knowledge of pressure ulcers prevention in families of patient at risk. During a 4 month period, 62 caregivers (78% family members and 22% non-related) filled out the questionnaire enquiring about the issue related to pressure ulcer prevention and treatment. Only 11% of questioned person knew what the pressure ulcer was, 42% of caregivers were not aware of possible pressure ulcer causes, and 54.8% were not able to mention any pressure ulcer risk factor. Most of caregivers did not know basic principles of prevention including devices useful in pressure ulcer prevention, did not know about pressure reducing mattresses nor dressings used in pressure ulcers treatment. Fifty three percent of questioned persons never received any information about pressure ulcer prevention, and only 23% received such information from nurses--which reflects low involvement of professional staff in education of families of patients at risk in principles of pressure ulcers prevention. Families and caregivers of bed-ridden patients have insufficient knowledge of pressure ulcer prevention. Contribution of medical staff in education of families of patients at risk in pressure ulcer prevention is minimal, indicating the need of preparation and implementation of an educational program for bed-ridden patients' caregivers.

[Urinary incontinence as a risk factor for pressure sores does not withstand a critical examination].

PubMed

Krause, Tom; Anders, Jennifer; von Renteln-Kruse, Wolfgang

2005-10-01

The association between urinary incontinence and pressure sores is put down to various causes. Most frequently urinary wet and following maceration of the skin are mentioned. However, it is possible that urinary incontinence is only an indicator for other risk factors or a measure of the need for care without any causal relation to pressure sores. There are hardly any controlled or randomised studies; this lack of scientific evidence is problematic. Based on a case-control-study including data of 200 patients as well as on the existing models of explanation, the following study tries to examine critically the connections between pressure sores and urinary incontinence. Out of the patients in our study population 97.5 percent were incontinent. Different categories of the risk factor urinary incontinence and different dichotomisations have led to different statistical results. Statements concerning the connection between urinary incontinence and pressure sores have to be interpreted critically. The dependence of urinary incontinence on other risk factors such as patients' need for care or compliance suggests that the causal connection to pressure sores be not reduced to the influence of wetness. We advise to research connections between urinary incontinence and pressure sores in a methodologically appropriate setting.

Clinical evaluation of a new pressure ulcer risk assessment instrument, the Pressure Ulcer Risk Primary or Secondary Evaluation Tool (PURPOSE T).

PubMed

Coleman, Susanne; Smith, Isabelle L; McGinnis, Elizabeth; Keen, Justin; Muir, Delia; Wilson, Lyn; Stubbs, Nikki; Dealey, Carol; Brown, Sarah; Nelson, E Andrea; Nixon, Jane

2018-02-01

To test the psychometric properties and clinical usability of a new Pressure Ulcer Risk Assessment Instrument including inter-rater and test-retest reliability, convergent validity and data completeness. Methodological and practical limitations associated with traditional Pressure Ulcer Risk Assessment Instruments, prompted a programme to work to develop a new instrument, as part of the National Institute for Health Research funded, Pressure UlceR Programme Of reSEarch (RP-PG-0407-10056). Observational field test. For this clinical evaluation 230 patients were purposefully sampled across four broad levels of pressure ulcer risk with representation from four secondary care and four community NHS Trusts in England. Blinded and simultaneous paired (ward/community nurse and expert nurse) PURPOSE-T assessments were undertaken. Follow-up retest was undertaken by the expert nurse. Field notes of PURPOSE-T use were collected. Data were collected October 2012-January 2013. The clinical evaluation demonstrated "very good" (kappa) inter-rater and test-retest agreement for PURPOSE-T assessment decision overall. The percentage agreement for "problem/no problem" was over 75% for the main risk factors. Convergent validity demonstrated moderate to high associations with other measures of similar constructs. The PURPOSE-T evaluation facilitated the initial validation and clinical usability of the instrument and demonstrated that PURPOSE-T is suitable of use in clinical practice. Further study is needed to evaluate the impact of using the instrument on care processes and outcomes. © 2017 The Authors. Journal of Advanced Nursing Published by John Wiley & Sons Ltd.

Modeling the pressure-dilatation correlation

NASA Technical Reports Server (NTRS)

Sarkar, S.

1991-01-01

It is generally accepted that pressure dilatation, which is an additional compressibility term in turbulence transport equations, may be important for high speed flows. Recent direct simulations of homogeneous shear turbulence have given concrete evidence that the pressure dilatation is important insofar that it contributes to the reduced growth of turbulent kinetic energy due to compressibility effects. The problem of modeling pressure dilatation is addressed. A component of the pressure dilatation is isolated which exhibits temporal oscillations and, using direct numerical simulations of homogeneous shear turbulence and isotropic turbulence, show that it has a negligible contribution to the evolution of turbulent kinetic energy. Then, an analysis for the case of homogeneous turbulence is performed to obtain a model for the nonoscillatory pressure dilatation. This model algebraically relates the pressure dilatation to quantities traditionally obtained in incompressible turbulence closures. The model is validated by direct comparison with the pressure dilatation data obtained from the simulations.

Pressure ulcer risk assessment and prevention: what difference does a risk scale make? A comparison between Norway and Ireland.

PubMed

Johansen, E; Moore, Z; van Etten, M; Strapp, H

2014-07-01

To explore similarities and differences in nurses' views on risk assessment practices and preventive care activities in a context where patients' risk of developing pressure ulcers is assessed using clinical judgment (Norway) and a context where patients' risk of developing pressure ulcers is assessed using a formal structured risk assessment combined with clinical judgement (Ireland). A descriptive, qualitative design was employed across two different care settings with a total of 14 health care workers, nine from Norway and five from Ireland. Regardless of whether risk assessment was undertaken using clinical judgment or formal structured risk assessment, identified risk factors, at risk patients and appropriate preventive initiatives discussed by participant were similar across care settings. Furthermore, risk assessment did not necessarily result in the planning and implementation of appropriate pressure ulcer prevention initiatives. Thus, in this instance, use of a formal risk assessment tool does not seem to make any difference to the planning, initiation and evaluation of pressure ulcer prevention strategies. Regardless of the method of risk assessment, patients at risk of developing pressure ulcers are detected, suggesting that the practice of risk assessment should be re-evaluated. Moreover, appropriate preventive interventions were described. However, the missing link between risk assessment and documented care planning is of concern and barriers to appropriate pressure ulcer documentation should be explored further. This work is partly funded by a research grant from the Norwegian Nurses Organisation (NNO) (Norsk Sykepleierforbund NSF) in 2012. The authors have no conflict of interest to declare.

Pressure ulcer risk assessment and prevention: a systematic comparative effectiveness review.

PubMed

Chou, Roger; Dana, Tracy; Bougatsos, Christina; Blazina, Ian; Starmer, Amy J; Reitel, Katie; Buckley, David I

2013-07-02

Pressure ulcers are associated with substantial health burdens but may be preventable. To review the clinical utility of pressure ulcer risk assessment instruments and the comparative effectiveness of preventive interventions in persons at higher risk. MEDLINE (1946 through November 2012), CINAHL, the Cochrane Library, grant databases, clinical trial registries, and reference lists. Randomized trials and observational studies on effects of using risk assessment on clinical outcomes and randomized trials of preventive interventions on clinical outcomes. Multiple investigators abstracted and checked study details and quality using predefined criteria. One good-quality trial found no evidence that use of a pressure ulcer risk assessment instrument, with or without a protocolized intervention strategy based on assessed risk, reduces risk for incident pressure ulcers compared with less standardized risk assessment based on nurses' clinical judgment. In higher-risk populations, 1 good-quality and 4 fair-quality randomized trials found that more advanced static support surfaces were associated with lower risk for pressure ulcers compared with standard mattresses (relative risk range, 0.20 to 0.60). Evidence on the effectiveness of low-air-loss and alternating-air mattresses was limited, with some trials showing no clear differences from advanced static support surfaces. Evidence on the effectiveness of nutritional supplementation, repositioning, and skin care interventions versus usual care was limited and had methodological shortcomings, precluding strong conclusions. Only English-language articles were included, publication bias could not be formally assessed, and most studies had methodological shortcomings. More advanced static support surfaces are more effective than standard mattresses for preventing ulcers in higher-risk populations. The effectiveness of formal risk assessment instruments and associated intervention protocols compared with less standardized

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.

Blood pressure variability and risk of cardiovascular events and death in patients with hypertension and different baseline risks.

PubMed

Mehlum, Maria H; Liestøl, Knut; Kjeldsen, Sverre E; Julius, Stevo; Hua, Tsushung A; Rothwell, Peter M; Mancia, Giuseppe; Parati, Gianfranco; Weber, Michael A; Berge, Eivind

2018-01-20

Blood pressure variability is associated with increased risk of cardiovascular events, particularly in high-risk patients. We assessed if variability was associated with increased risk of cardiovascular events and death in hypertensive patients at different risk levels. The Valsartan Antihypertensive Long-term Use Evaluation trial was a randomized controlled trial of valsartan vs. amlodipine in patients with hypertension and different risks of cardiovascular events, followed for a mean of 4.2 years. We calculated standard deviation (SD) of mean systolic blood pressure from visits from 6 months onward in patients with ≥3 visits and no events during the first 6 months. We compared the risk of cardiovascular events in the highest and lowest quintile of visit-to-visit blood pressure variability, using Cox regression. For analysis of death, variability was analysed as a continuous variable. Of 13 803 patients included, 1557 (11.3%) had a cardiovascular event and 1089 (7.9%) died. Patients in the highest quintile of SD had an increased risk of cardiovascular events [hazard ratio (HR) 2.1, 95% confidence interval (95% CI) 1.7-2.4; P < 0.0001], and a 5 mmHg increase in SD of systolic blood pressure was associated with a 10% increase in the risk of death (HR 1.10, 95% CI 1.04-1.17; P = 0.002). Associations were stronger among younger patients and patients with lower systolic blood pressure, and similar between patients with different baseline risks, except for higher risk of death among patients with established cardiovascular disease. Higher visit-to-visit systolic blood pressure variability is associated with increased risk of cardiovascular events in patients with hypertension, irrespective of baseline risk of cardiovascular events. Associations were stronger in younger patients and in those with lower mean systolic blood pressure. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2018. For permissions

Benefit and harm of intensive blood pressure treatment: Derivation and validation of risk models using data from the SPRINT and ACCORD trials

PubMed Central

Denton, Brian T.; Hayward, Rodney A.

2017-01-01

Background Intensive blood pressure (BP) treatment can avert cardiovascular disease (CVD) events but can cause some serious adverse events. We sought to develop and validate risk models for predicting absolute risk difference (increased risk or decreased risk) for CVD events and serious adverse events from intensive BP therapy. A secondary aim was to test if the statistical method of elastic net regularization would improve the estimation of risk models for predicting absolute risk difference, as compared to a traditional backwards variable selection approach. Methods and findings Cox models were derived from SPRINT trial data and validated on ACCORD-BP trial data to estimate risk of CVD events and serious adverse events; the models included terms for intensive BP treatment and heterogeneous response to intensive treatment. The Cox models were then used to estimate the absolute reduction in probability of CVD events (benefit) and absolute increase in probability of serious adverse events (harm) for each individual from intensive treatment. We compared the method of elastic net regularization, which uses repeated internal cross-validation to select variables and estimate coefficients in the presence of collinearity, to a traditional backwards variable selection approach. Data from 9,069 SPRINT participants with complete data on covariates were utilized for model development, and data from 4,498 ACCORD-BP participants with complete data were utilized for model validation. Participants were exposed to intensive (goal systolic pressure < 120 mm Hg) versus standard (<140 mm Hg) treatment. Two composite primary outcome measures were evaluated: (i) CVD events/deaths (myocardial infarction, acute coronary syndrome, stroke, congestive heart failure, or CVD death), and (ii) serious adverse events (hypotension, syncope, electrolyte abnormalities, bradycardia, or acute kidney injury/failure). The model for CVD chosen through elastic net regularization included interaction

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

PubMed

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.

High Blood Pressure, Afib and Your Risk of Stroke

MedlinePlus

... Peripheral Artery Disease Venous Thromboembolism Aortic Aneurysm More High Blood Pressure, AFib and Your Risk of Stroke Updated:Aug ... have a stroke for the first time have high blood pressure . And an irregular atrial heart rhythm — a condition ...

A model of psychosocial and cultural antecedents of blood pressure control.

PubMed Central

Bosworth, Hayden B.; Oddone, Eugene Z.

2002-01-01

Hypertension is a major modifiable risk factor for stroke, congestive heart failure, and end-stage renal disease. Hypertension is particularly prevalent and deadly among African Americans. Effective treatment for hypertension has been available for decades, yet only one fourth of all individuals have their blood pressure under control. Despite the potential impact of hypertension, interventions to improve control have had limited success. We present a model of how to understand antecedents of blood pressure control according to three interrelated categories: patient characteristics, social and cultural environment, and medical environment. This theoretical paper was conducted using a literature review and a model to explain psychosocial antecedents of blood pressure control is presented. We conclude that improved understanding of important antecedents of blood pressure control coupled with technological advances, such as tailored interventions, provide clinicians with a tool that may lead to improved blood pressure control. These interventions will require the involvement of clinicians and consideration of sociocultural factors to be successful. PMID:11991336

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

The clinical relevance of the Waterlow pressure sore risk scale in the ICU.

PubMed

Weststrate, J T; Hop, W C; Aalbers, A G; Vreeling, A W; Bruining, H A

1998-08-01

To evaluate whether the Waterlow pressure sore risk (PSR) scale has prognostic significance for intensive care patients. A prospective study. The surgical intensive care unit (ICU) of the University Hospital Rotterdam. Data were evaluated from 594 patients who had been admitted to the ICU during the year 1994. Each patient was assessed daily with respect to their Waterlow PSR score and the development of pressure sores in the sacral region. Actuarial statistical methods were used to analyse the predictive value of the risk score. When a patient had a Waterlow PSR score > 25 on admission, the risk of developing a pressure sore was significantly increased compared to patients with a PSR score < 25. After admission, the daily Waterlow PSR scores obtained were significantly associated with the risk of developing a pressure sore. For each additional point this risk increased by 23% (95% confidence interval 17 to 28%). The Waterlow PSR scale provides the medical and nursing staff at an early stage with reliable information about the risk patients have in developing a pressure sore.

Successful implementation of clinical practice guidelines for pressure risk management in a home nursing setting.

PubMed

Kapp, Suzanne

2013-10-01

This paper reports an initiative which promoted evidence-based practice in pressure risk assessment and management among home nursing clients in Melbourne, Australia. The aim of this study was to evaluate the introduction and uptake of the Australian Wound Management Association Guidelines for the Prediction and Prevention of Pressure Ulcers. In 2007 a pilot study was conducted. Nurse perspectives (n=21) were obtained via survey and a client profile (n=218) was generated. Audit of the uptake and continued use of the pressure risk screening tool, during the pilot study and later once implemented as standard practice organizational wide, was conducted. Nurses at the pilot site successfully implemented the practice guidelines, pressure risk screening was adopted and supporting resources were well received. Most clients were at low risk of pressure ulcer development. The pilot site maintained and extended their pilot study success, ensuring more than 90% of clients were screened for pressure risk over the 18 months which followed. All other sites performed less well initially, however subsequently improved, meeting the pilot sites success after 18 months. Two years later, the organization continues to screen more than 90% of all clients for pressure risk. Implementation of clinical practice guidelines was successful in the pilot project and pressure risk screening became a well-adopted practice. Success continued following organizational wide implementation. Pilot study findings suggest it may be prudent to monitor the pressure ulcer risk status of low risk clients so as to prevent increasing risk and pressure ulcer development among this group. © 2012 John Wiley & Sons Ltd.

Utility of blood pressure genetic risk score in admixed Hispanic samples.

PubMed

Beecham, A H; Wang, L; Vasudeva, N; Liu, Z; Dong, C; Goldschmidt-Clermont, P J; Pericak-Vance, M A; Rundek, T; Seo, D; Blanton, S H; Sacco, R L; Beecham, G W

2016-12-01

Hypertension is strongly influenced by genetic factors. Although hypertension prevalence in some Hispanic sub-populations is greater than in non-Hispanic whites, genetic studies on hypertension have focused primarily on samples of European descent. A recent meta-analysis of 200 000 individuals of European descent identified 29 common genetic variants that influence blood pressure, and a genetic risk score derived from the 29 variants has been proposed. We sought to evaluate the utility of this genetic risk score in Hispanics. The sample set consists of 1994 Hispanics from 2 cohorts: the Northern Manhattan Study (primarily Dominican/Puerto Rican) and the Miami Cardiovascular Registry (primarily Cuban/South American). Risk scores for systolic and diastolic blood pressure were computed as a weighted sum of the risk alleles, with the regression coefficients reported in the European meta-analysis used as weights. Association of risk score with blood pressure was tested within each cohort, adjusting for age, age 2 , sex and body mass index. Results were combined using an inverse-variance meta-analysis. The risk score was significantly associated with blood pressure in our combined sample (P=5.65 × 10 -4 for systolic and P=1.65 × 10 -3 for diastolic) but the magnitude of the effect sizes varied by degree of European, African and Native American admixture. Further studies among other Hispanic sub-populations are needed to elucidate the role of these 29 variants and identify additional genetic and environmental factors contributing to blood pressure variability in Hispanics.

Pressure Ulcer Risk Evaluation in Critical Patients: Clinical and Social Characteristics.

PubMed

de Azevedo Macena, Mônica Suêla; da Costa Silva, Rayanne Suely; Dias Fernandes, Maria Isabel Da Conceição; de Almeida Medeiros, Ana Beatriz; Batista Lúcio, Kadyjina Daiane; de Carvalho Lira, Ana Luisa Brandão

2017-01-01

Pressure ulcers increase hospital stays and treatment costs due to their complications. Therefore, recognizing factors that contribute to pressure ulcer risk are important to patient safety. To evaluate the association between the scores of the Waterlow, Braden, and Norton scales and clinical and social characteristics in critically ill patients. A cross-sectional study of 78 patients in an adult intensive care unit of a university hospital in Northeastern Brazil was conducted from July to December 2015. Data included social and clinical information and the risk factors of the Braden, Norton and Waterlow scales. Data were analysed by the descriptive and inferential statistics. Most of the participants were female, adults and elderly people with brown skin colour, low education levels and insufficient income. Most of them showed a high risk for developing pressure ulcers using the three evaluated scales. Age, smoking status, diabetes and hypertension were associated with scores on the Waterlow, Braden and Norton scales. Age, use of the tobacco, diabetes and hypertension were associated with the risk of pressure ulcers in ICU patients.

Automated Pressure Injury Risk Assessment System Incorporated Into an Electronic Health Record System.

PubMed

Jin, Yinji; Jin, Taixian; Lee, Sun-Mi

Pressure injury risk assessment is the first step toward preventing pressure injuries, but traditional assessment tools are time-consuming, resulting in work overload and fatigue for nurses. The objectives of the study were to build an automated pressure injury risk assessment system (Auto-PIRAS) that can assess pressure injury risk using data, without requiring nurses to collect or input additional data, and to evaluate the validity of this assessment tool. A retrospective case-control study and a system development study were conducted in a 1,355-bed university hospital in Seoul, South Korea. A total of 1,305 pressure injury patients and 5,220 nonpressure injury patients participated for the development of a risk scoring algorithm: 687 and 2,748 for the validation of the algorithm and 237 and 994 for validation after clinical implementation, respectively. A total of 4,211 pressure injury-related clinical variables were extracted from the electronic health record (EHR) systems to develop a risk scoring algorithm, which was validated and incorporated into the EHR. That program was further evaluated for predictive and concurrent validity. Auto-PIRAS, incorporated into the EHR system, assigned a risk assessment score of high, moderate, or low and displayed this on the Kardex nursing record screen. Risk scores were updated nightly according to 10 predetermined risk factors. The predictive validity measures of the algorithm validation stage were as follows: sensitivity = .87, specificity = .90, positive predictive value = .68, negative predictive value = .97, Youden index = .77, and the area under the receiver operating characteristic curve = .95. The predictive validity measures of the Braden Scale were as follows: sensitivity = .77, specificity = .93, positive predictive value = .72, negative predictive value = .95, Youden index = .70, and the area under the receiver operating characteristic curve = .85. The kappa of the Auto-PIRAS and Braden Scale risk

Sound pressure levels generated at risk volume steps of portable listening devices: types of smartphone and genres of music.

PubMed

Kim, Gibbeum; Han, Woojae

2018-05-01

The present study estimated the sound pressure levels of various music genres at the volume steps that contemporary smartphones deliver, because these levels put the listener at potential risk for hearing loss. Using six different smartphones (Galaxy S6, Galaxy Note 3, iPhone 5S, iPhone 6, LG G2, and LG G3), the sound pressure levels for three genres of K-pop music (dance-pop, hip-hop, and pop-ballad) and a Billboard pop chart of assorted genres were measured through an earbud for the first risk volume that was at the risk sign proposed by the smartphones, as well as consecutive higher volumes using a sound level meter and artificial mastoid. The first risk volume step of the Galaxy S6 and the LG G2, among the six smartphones, had the significantly lowest (84.1 dBA) and highest output levels (92.4 dBA), respectively. As the volume step increased, so did the sound pressure levels. The iPhone 6 was loudest (113.1 dBA) at the maximum volume step. Of the music genres, dance-pop showed the highest output level (91.1 dBA) for all smartphones. Within the frequency range of 20~ 20,000 Hz, the sound pressure level peaked at 2000 Hz for all the smartphones. The results showed that the sound pressure levels of either the first volume step or the maximum volume step were not the same for the different smartphone models and genres of music, which means that the risk volume sign and its output levels should be unified across the devices for their users. In addition, the risk volume steps proposed by the latest smartphone models are high enough to cause noise-induced hearing loss if their users habitually listen to music at those levels.

Promoting evidence-based practice: managing change in the assessment of pressure damage risk.

PubMed

Gerrish, K; Clayton, J; Nolan, M; Parker, K; Morgan, L

1999-11-01

This study set out to facilitate the development of evidence-based practice in the assessment of pressure damage risk to patients within a large acute hospital. The importance of nursing practice being based on the best available evidence is emphasized in recent health policy. Meeting this objective is not easy as both individual and organizational factors create barriers to the implementation of research findings and the achievement of change. The study was based on an action research model. It comprised three stages: a review of the research evidence; a survey of qualified nurses' knowledge of risk assessment of pressure damage and an audit of record keeping, and a multifaceted approach to achieving change in which researchers, managers, practitioners and clinical nurse specialists worked together collaboratively. The findings from the survey and audit indicated a shortfall in nurses' knowledge of risk assessment of pressure damage and in their record keeping. The researchers, with the help of the clinical nurse specialist, built upon these findings by assisting practitioners and managers to take ownership of the need to base practice on the appropriate evidence. Achieving evidence-based practice is a complex undertaking that requires the development of an evaluative culture and a commitment by practitioners and managers to change practice. Researchers can play a valuable role in facilitating this process.

A Novel Rat Model to Study the Role of Intracranial Pressure Modulation on Optic Neuropathies

PubMed Central

Roy Chowdhury, Uttio; Holman, Bradley H.; Fautsch, Michael P.

2013-01-01

Reduced intracranial pressure is considered a risk factor for glaucomatous optic neuropathies. All current data supporting intracranial pressure as a glaucoma risk factor comes from retrospective and prospective studies. Unfortunately, there are no relevant animal models for investigating this link experimentally. Here we report a novel rat model that can be used to study the role of intracranial pressure modulation on optic neuropathies. Stainless steel cannulae were inserted into the cisterna magna or the lateral ventricle of Sprague-Dawley and Brown Norway rats. The cannula was attached to a pressure transducer connected to a computer that recorded intracranial pressure in real-time. Intracranial pressure was modulated manually by adjusting the height of a column filled with artificial cerebrospinal fluid in relation to the animal’s head. After data collection the morphological appearance of the brain tissue was analyzed. Based on ease of surgery and ability to retain the cannula, Brown Norway rats with the cannula implanted in the lateral ventricle were selected for further studies. Baseline intracranial pressure for rats was 5.5±1.5 cm water (n=5). Lowering of the artificial cerebrospinal fluid column by 2 cm and 4 cm below head level reduced ICP to 3.7±1.0 cm water (n=5) and 1.5±0.6 cm water (n=4), a reduction of 33.0% and 72.7% below baseline. Raising the cerebrospinal fluid column by 4 cm increased ICP to 7.5±1.4 cm water (n=2) corresponding to a 38.3% increase in intracranial pressure. Histological studies confirmed correct cannula placement and indicated minimal invasive damage to brain tissues. Our data suggests that the intraventricular cannula model is a unique and viable model that can be used to study the effect of altered intracranial pressure on glaucomatous optic neuropathies. PMID:24367501

Hurricane risk mitigation - High Pressure Gas Facility

NASA Image and Video Library

2008-07-29

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.

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.

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.

Couple resilience to economic pressure.

PubMed

Conger, R D; Rueter, M A; Elder, G H

1999-01-01

Over 400 married couples participated in a 3-year prospective study of economic pressure and marital relations. The research (a) empirically evaluated the family stress model of economic stress influences on marital distress and (b) extended the model to include specific interactional characteristics of spouses hypothesized to protect against economic pressure. Findings provided support for the basic mediational model, which proposes that economic pressure increases risk for emotional distress, which, in turn, increases risk for marital conflict and subsequent marital distress. Regarding resilience to economic stress, high marital support reduced the association between economic pressure and emotional distress. In addition, effective couple problem solving reduced the adverse influence of marital conflict on marital distress. Overall, the findings provided substantial support for the extended family stress model.

Therapeutic hypothermia and pressure ulcer risk in critically ill intensive care patients: A retrospective study.

PubMed

Ahtiala, Maarit; Laitio, Ruut; Soppi, Esa

2018-06-01

To examine the role of therapeutic hypothermia in pressure ulcer development in critically ill patients. Retrospective study in a mixed intensive care unit over 2010-2013. The incidences of pressure ulcers among patients treated with therapeutic hypothermia (n = 148) and the non-hypothermia patient population (n = 6197) were compared. Patients treated with hypothermia developed more pressure ulcers (25.0%) than the non-hypothermia group 6.3% (p < 0.001). More patients in the hypothermia group were rated as the high pressure ulcer risk group, as defined by the modified Jackson/Cubbin (mJ/C) risk score ≤29 than the rest of the patients. Among the therapeutic hypothermia patients more pressure ulcers tended to emerge in the lower risk group (mJ/C score ≥30) (p = 0.056). Intensive care mortality was higher in the hypothermia (24.3%) than the non-hypothermia group (9.3%, p < 0.0001). Patients treated with therapeutic hypothermia should be considered at high risk for pressure ulcer development and should be managed accordingly. The hypothermia may not as such increase the risk for pressure ulcers, but combined with the severity of the underlying illness, may be more likely. The pressure ulcer risk in this patient group cannot be reliably assessed by the Jackson/Cubbin risk scale. Copyright © 2018 Elsevier Ltd. All rights reserved.

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. © 2015 American Heart Association, Inc.

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

PubMed

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

2015-01-01

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. 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. 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. 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). 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 interventions.

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

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.

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. Copyright © 2011 Elsevier B.V. All rights reserved.

Impact of comprehensive cardiovascular risk reduction programme on risk factor clustering associated with elevated blood pressure in an Indian industrial population.

PubMed

Jeemon, Panniyammakal; Prabhakaran, Dorairaj; Goenka, Shifalika; Ramakrishnan, Lakshmy; Padmanabhan, Sandosh; Huffman, Mark; Joshi, Prashant; Sivasankaran, Sivasubramonian; Mohan, B V M; Ahmed, F; Ramanathan, Meera; Ahuja, R; Sinha, Nakul; Thankappan, K R; Reddy, K S

2012-04-01

Cardiovascular risk factors clustering associated with blood pressure (BP) has not been studied in the Indian population. This study was aimed at assessing the clustering effect of cardiovascular risk factors with suboptimal BP in Indian population as also the impact of risk reduction interventions. Data from 10543 individuals collected in a nation-wide surveillance programme in India were analysed. The burden of risk factors clustering with blood pressure and coronary heart disease (CHD) was assessed. The impact of a risk reduction programmme on risk factors clustering was prospectively studied in a sub-group. Mean age of participants was 40.9 ± 11.0 yr. A significant linear increase in number of risk factors with increasing blood pressure, irrespective of stratifying using different risk factor thresholds was observed. While hypertension occurred in isolation in 2.6 per cent of the total population, co-existence of hypertension and >3 risk factors was observed in 12.3 per cent population. A comprehensive risk reduction programme significantly reduced the mean number of additional risk factors in the intervention population across the blood pressure groups, while it continued to be high in the control arm without interventions (both within group and between group P<0.001). The proportion of 'low risk phenotype' increased from 13.4 to 19.9 per cent in the intervention population and it was decreased from 27.8 to 10.6 per cent in the control population (P<0.001). The proportion of individuals with hypertension and three more risk factors decreased from 10.6 to 4.7 per cent in the intervention arm while it was increased from 13.3 to 17.8 per cent in the control arm (P<0.001). Our findings showed that cardiovascular risk factors clustered together with elevated blood pressure and a risk reduction programme significantly reduced the risk factors burden.

Prevalence of pressure ulcer and associated risk factors in middle- and older-aged medical inpatients in Norway.

PubMed

Børsting, Tove E; Tvedt, Christine R; Skogestad, Ingrid J; Granheim, Tove I; Gay, Caryl L; Lerdal, Anners

2018-02-01

To describe the prevalence of pressure ulcers among middle- and older-aged patients in a general medical hospital in Norway and to describe the associations between pressure ulcers and potential risk factors additional to the Braden risk score. Degrees of mobility, activity, perfusion and skin status are risk factors for development of pressure ulcer. Nurses' clinical judgements combined with risk assessment tools are effective to detect pressure ulcer risk. Cross-sectional study. The study was performed as part of a research project conducted between September 2012-May 2014 in a general hospital in the capital of Norway. Registered nurses and nursing students collected data from all eligible patients on 10 days during the students' clinical practice studies. The Braden scale was used to measure pressure ulcer risk, and skin examinations were performed to classify the skin area as normal or as indicative of pressure ulcer according to the definitions by the National Pressure Ulcer Advisory Panel. Comorbidities were collected by patient's self-report. This analysis focused on the 255 inpatients at the medical wards ≥52 years of age, most of whom had more than one comorbidity. The prevalence of pressure ulcers was 14.9% in this sample. Higher age, underweight, diabetes and worse Braden scores were factors associated with pressure ulcer, and pressure ulcer was most frequently sited at the sacrum or heel. Adding age, weight and diabetes status to pressure ulcer risk assessment scales may improve identification of patients at risk for pressure ulcers. Knowledge about strengths and limitations of risk assessment tools is important for clinical practice. Age, weight and diabetes status should be considered for inclusion in risk assessment tools for pressure ulcers in medical wards. © 2017 John Wiley & Sons Ltd.

How do microclimate factors affect the risk for superficial pressure ulcers: a mathematical modeling study.

PubMed

Gefen, Amit

2011-08-01

In this study, a mathematical model is developed for analyzing the effects of the microclimate on skin tolerance to superficial pressure ulcers (SPUs). The modeling identified the following factors as such that decrease the tolerance of skin to SPUs: (i) increase in the skin temperature, (ii) increase in the ambient temperature, (iii) increase in the relative humidity, (iv) increase in the skin-support (or skin-clothing-support) contact pressures, and (v) decrease in permeabilities of the materials contacting the skin or being close to it, e.g. the covering sheet of the support and clothing. The modeling is consistent with relevant empirical findings and clinical observations documented in the literature, explains them from a basic science aspect, and can be further developed for design of interventions, safer patient clothing and supports that consider the optimization of microclimate factors. Copyright © 2010 Tissue Viability Society. Published by Elsevier Ltd. All rights reserved.

Prophylactic Sacral Dressing for Pressure Ulcer Prevention in High-Risk Patients.

PubMed

Byrne, Jaime; Nichols, Patricia; Sroczynski, Marzena; Stelmaski, Laurie; Stetzer, Molly; Line, Cynthia; Carlin, Kristen

2016-05-01

Patients in intensive care units are likely to have limited mobility owing to hemodynamic instability and activity orders for bed rest. Bed rest is indicated because of the severity of the disease process, which often involves intubation, sedation, paralysis, surgical procedures, poor nutrition, low flow states, and poor circulation. These patients are predisposed to the development and/or the progression of pressure ulcers not only because of their underlying diseases, but also because of limited mobility and deconditioned states of health. To assess whether treating high-risk patients with a prophylactic sacral dressing decreases the incidence of unit-acquired sacral pressure ulcers. An evidence-based tool for identifying patients at high risk for pressure ulcers was used in 3 intensive care units at an urban tertiary care hospital and academic medical center. Those patients deemed at high risk had a prophylactic sacral dressing applied. Incidence rates were collected and compared for the 7 months preceding use of the dressings and for 7 months during the trial period when the dressing was used. After the sacral dressing began being used, the number of unit-acquired sacral pressure ulcers decreased by 3.4 to 7.6 per 1000 patient days depending on the unit. A prophylactic sacral dressing may help prevent unit-acquired sacral pressure ulcers. Implementation of an involved care team with heightened awareness and increased education along with a prophylactic sacral dressing in patients deemed high risk for skin breakdown are all essential for success. ©2016 American Association of Critical-Care Nurses.

Blood pressure-lowering treatment based on cardiovascular risk: a meta-analysis of individual patient data.

PubMed

2014-08-16

We aimed to investigate whether the benefits of blood pressure-lowering drugs are proportional to baseline cardiovascular risk, to establish whether absolute risk could be used to inform treatment decisions for blood pressure-lowering therapy, as is recommended for lipid-lowering therapy. This meta-analysis included individual participant data from trials that randomly assigned patients to either blood pressure-lowering drugs or placebo, or to more intensive or less intensive blood pressure-lowering regimens. The primary outcome was total major cardiovascular events, consisting of stroke, heart attack, heart failure, or cardiovascular death. Participants were separated into four categories of baseline 5-year major cardiovascular risk using a risk prediction equation developed from the placebo groups of the included trials (<11%, 11-15%, 15-21%, >21%). 11 trials and 26 randomised groups met the inclusion criteria, and included 67,475 individuals, of whom 51,917 had available data for the calculation of the risk equations. 4167 (8%) had a cardiovascular event during a median of 4·0 years (IQR 3·4-4·4) of follow-up. The mean estimated baseline levels of 5-year cardiovascular risk for each of the four risk groups were 6·0% (SD 2·0), 12·1% (1·5), 17·7% (1·7), and 26·8% (5·4). In each consecutive higher risk group, blood pressure-lowering treatment reduced the risk of cardiovascular events relatively by 18% (95% CI 7-27), 15% (4-25), 13% (2-22), and 15% (5-24), respectively (p=0·30 for trend). However, in absolute terms, treating 1000 patients in each group with blood pressure-lowering treatment for 5 years would prevent 14 (95% CI 8-21), 20 (8-31), 24 (8-40), and 38 (16-61) cardiovascular events, respectively (p=0·04 for trend). Lowering blood pressure provides similar relative protection at all levels of baseline cardiovascular risk, but progressively greater absolute risk reductions as baseline risk increases. These results support the use of predicted

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.

Twenty-Four-Hour Central Pulse Pressure for Cardiovascular Events Prediction in a Low-Cardiovascular-Risk Population: Results From the Bordeaux Cohort.

PubMed

Cremer, Antoine; Boulestreau, Romain; Gaillard, Prune; Lainé, Marion; Papaioannou, Georgios; Gosse, Philippe

2018-02-23

Central blood pressure (BP) is a promising marker to identify subjects with higher cardiovascular risk than expected by traditional risk factors. Significant results have been obtained in populations with high cardiovascular risk, but little is known about low-cardiovascular-risk patients, although the differences between central and peripheral BP (amplification) are usually greater in this population. The study aim was to evaluate central BP over 24 hours for cardiovascular event prediction in hypertensive subjects with low cardiovascular risk. Peripheral and central BPs were recorded during clinical visits and over 24 hours in hypertensive patients with low cardiovascular risk (Systematic Coronary Risk Evaluation ≤5%). Our primary end point is the occurrence of a cardiovascular event during follow-up. To assess the potential interest in central pulse pressure over 24 hours, we performed Cox proportional hazard models analysis and comparison of area under the curves using the contrast test for peripheral and central BP. A cohort of 703 hypertensive subjects from Bordeaux were included. After the first 24 hours of BP measurement, the subjects were then followed up for an average of 112.5±70 months. We recorded 65 cardiovascular events during follow-up. Amplification was found to be significantly associated with cardiovascular events when added to peripheral 24-hour pulse pressure ( P =0.0259). The area under the curve of 24-hour central pulse pressure is significantly more important than area under the curve of office BP ( P =0.0296), and there is a trend of superiority with the area under the curve of peripheral 24-hour pulse pressure. Central pulse pressure over 24 hours improves the prediction of cardiovascular events for hypertensive patients with low cardiovascular risk compared to peripheral pulse pressure. © 2018 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.

[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.

Development of a Personalized Model for Pressure Ulcer Prevention Acutely Following Spinal Cord Injury: Biomarkers of Muscle Composition and Resilience

DTIC Science & Technology

2015-10-01

AWARD NUMBER: W81XWH-14-1-0618 TITLE: Development of a Personalized Model for Pressure Ulcer Prevention Acutely Following Spinal Cord Injury...Model for Pressure Ulcer Prevention Acutely Following Spinal Cord Injury: Biomarkers of Muscle Composition and Resilience 5a. CONTRACT NUMBER...military and veterans. All persons with SCI are at increased risk of pressure ulcer development which remains one of the most significant secondary

Pressure Ulcer Prevalence and Risk Factors among Prolonged Surgical Procedures in the OR

PubMed Central

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

2015-01-01

Pressure ulcer formation related to positioning in the OR increases 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 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 admit 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) (χ2 = 7.897, P = .048), OR bed surface (ie, foam table pad) (χ2 15.848, P = .000), skin assessment in the postanesthesia care unit (χ2 = 41.652, P = .000), and male gender (χ2 = 6.984, P = .030) were associated with pressure ulcer development. Logistic regression analyses indicated that use of foam pad (B = 2.691, P = .024) and a lower day-one Braden score (B = .244, P = .003) were predictive of pressure ulcers. PMID:22118201

The association between cardiovascular risk factors and high blood pressure in adolescents: a school-based study.

PubMed

Christofaro, Diego G D; Fernandes, Rômulo A; Oliveira, Arli R; Freitas Júnior, Ismael Forte; Barros, Mauro V G; Ritti-Dias, Raphael M

2014-01-01

Although previous studies have analyzed the association between cardiovascular risk factors and blood pressure in adolescents, few studies conducted in developing countries analyzed whether the aggregation of risk factors contributes to an increased risk of high blood pressure in adolescents. The objective of this study was to assess the association between cardiovascular risk factors (including general overweight, abdominal obesity, high consumption of foods rich in fats, and insufficient physical activity levels) and high blood pressure in adolescents. This study was carried out from 2007 to 2008 with 1021 adolescents (528 girls) from primary schools located in the city of Londrina- Brazil. Blood pressure was assessed using an oscillometric device. General overweight was obtained through body mass index, abdominal obesity was assessed using waist circumference, and the consumption of foods rich in fat and physical activity were assessed using a questionnaire. The sum of these risk factors was determined. Adolescents with three or four aggregated risk factors were more likely to have higher values of systolic and diastolic blood pressure when compared with adolescents who did not have any cardiovascular risk factors (P = 0.001 for both). Logistic regression indicated that groups of adolescents with 2 (OR= 2.46 [1.11-5.42]; P = 0.026), 3 (OR= 4.97 [2.07-11.92]; P = 0.001) or 4 risk factors (OR= 6.79 [2.24-19.9]; P = 0.001) presented an increased likelihood of high blood pressure. The number of cardiovascular risk factors was found to be related to high blood pressure in adolescents. Copyright © 2014 Wiley Periodicals, Inc.

Peer pressure and Generalised Lotka Volterra models

NASA Astrophysics Data System (ADS)

Richmond, Peter; Sabatelli, Lorenzo

2004-12-01

We develop a novel approach to peer pressure and Generalised Lotka-Volterra (GLV) models that builds on the development of a simple Langevin equation that characterises stochastic processes. We generalise the approach to stochastic equations that model interacting agents. The agent models recently advocated by Marsilli and Solomon are motivated. Using a simple change of variable, we show that the peer pressure model (similar to the one introduced by Marsilli) and the wealth dynamics model of Solomon may be (almost) mapped one into the other. This may help shed light in the (apparently) different wealth dynamics described by GLV and the Marsili-like peer pressure models.

Pressure ulcer prevention in high-risk postoperative cardiovascular patients.

PubMed

Jackson, Melissa; McKenney, Teresa; Drumm, Jennifer; Merrick, Brian; LeMaster, Tamara; VanGilder, Catherine

2011-08-01

Little has been published about how to prevent pressure ulcers in severely debilitated, immobile patients in intensive care units. To present a possible prevention strategy for postoperative cardiovascular surgery patients at high risk for development of pressure ulcers. Staff chose to implement air fluidized therapy beds, which provide maximal immersion and envelopment as a measure for preventing pressure ulcers in patients who (1) required vasopressors for at least 24 hours and (2) required mechanical ventilation for at least 24 hours postoperatively. Only 1 of 27 patients had a pressure ulcer develop while on the air fluidized therapy bed (February 2008 through August 2008), and that ulcer was only a stage I ulcer, compared with 40 ulcers in 25 patients before the intervention. Patients spent a mean of 7.9 days on the mattress, and the cost of bed rental was approximately $18000, which was similar to the cost of treatment of 1 pressure ulcer in stage III or IV (about $40000) and was considered cost-effective.

Dry skin and pressure ulcer risk: A multi-center cross-sectional prevalence study in German hospitals and nursing homes.

PubMed

Lechner, Anna; Lahmann, Nils; Neumann, Konrad; Blume-Peytavi, Ulrike; Kottner, Jan

2017-08-01

Pressure ulcers are a serious health problem in medical and nursing care. Therefore, effective prevention is crucial. Major pressure ulcer risk factors have been identified but the particular role of dry skin (xerosis cutis) is unclear. To investigate possible associations between dry skin and pressure ulcers focusing on the sacrum/trochanter and at heel/ankle skin areas. Two multicenter cross-sectional studies. In 2014 and 2015 thirty nursing homes and thirteen hospitals in Germany participated. In total 3837 participants were included. Mean age was 76.1 (SD 15.5) years. Skin assessments and data collection were performed by trained nurses based on a standardized data collection form. Descriptive comparisons and multilevel logistic regressions predicting pressure ulcers at sacrum/trochanter and ankle/heel were conducted. The prevalence of skin dryness at the trunk was significantly higher for subjects with pressure ulcers category 2+ at the sacral area compared to without (39.0% vs. 24.4%, p=0.010). Adjusted to demographic variables, mobility and type of institution dry skin at the trunk was no longer associated with pressure ulceration (OR 1.11 (95% CI 0.62-2.00)). 71.9% of patients with heel/ankle pressure ulcers category 2+ were affected by dry skin at legs or feet, compared to 42.8% of subjects without pressure ulcers (p<0.001). In the adjusted analysis the OR was 1.85 (95% CI 0.83-4.14). Study results indicate that dry skin at the feet may be considered as a risk factor for heel pressure ulcer development. Skin dryness may be less important for sacral pressure ulcers. Therefore, the variable skin status should be better defined in future studies and pressure ulcer risk models. Results further support differences in pressure ulcer aetiologies between anatomical locations. Copyright © 2017 Elsevier Ltd. All rights reserved.

RISK FACTORS FOR PRESSURE INJURIES AMONG CRITICAL-CARE PATIENTS: A SYSTEMATIC REVIEW

PubMed Central

Alderden, Jenny; Rondinelli, June; Pepper, Ginette; Cummins, Mollie; Whitney, JoAnne

2017-01-01

Objective To identify risk factors independently predictive of pressure injury (also known as pressure ulcer) development among critical-care patients Design We undertook a systematic review of primary research based on standardized criteria set forth by the Institute of Medicine. Data Sources We searched the following databases: CINAHL (EBSCOhost), the Cochrane Library (Wilson), Dissertations & Theses Global (ProQuest), PubMed (National Library of Medicine), and Scopus. There was no language restriction. Method A research librarian coordinated the search strategy. Articles that potentially met inclusion criteria were screened by two investigators. Among the articles that met selection criteria, one investigator extracted data and a second investigator reviewed the data for accuracy. Based on a literature search, we developed a tool for assessing study quality using a combination of currently available tools and expert input. We used the method developed by Coleman and colleagues in 2014 to generate evidence tables and a summary narrative synthesis by domain and subdomain. Results Of 1753 abstracts reviewed, 158 were identified as potentially eligible and 18 fulfilled eligibility criteria. Five studies were classified as high quality, two were moderate quality, nine were low quality, and two were of very low quality. Age, mobility/activity, perfusion, and vasopressor infusion emerged as important risk factors for pressure injury development, whereas results for risk categories that are theoretically important, including nutrition, and skin/pressure injury status, were mixed. Methodological limitations across studies limited the generalizability of the results, and future research is needed, particularly to evaluate risk conferred by altered nutrition and skin/pressure injury status, and to further elucidate the effects of perfusion-related variables. Conclusions Results underscore the importance of avoiding overinterpretation of a single study, and the importance

Blood pressure load does not add to ambulatory blood pressure level for cardiovascular risk stratification.

PubMed

Li, Yan; Thijs, Lutgarde; Boggia, José; Asayama, Kei; Hansen, Tine W; Kikuya, Masahiro; Björklund-Bodegård, Kristina; Ohkubo, Takayoshi; Jeppesen, Jørgen; Torp-Pedersen, Christian; Dolan, Eamon; Kuznetsova, Tatiana; Stolarz-Skrzypek, Katarzyna; Tikhonoff, Valérie; Malyutina, Sofia; Casiglia, Edoardo; Nikitin, Yuri; Lind, Lars; Sandoya, Edgardo; Kawecka-Jaszcz, Kalina; Filipovsky, Jan; Imai, Yutaka; Ibsen, Hans; O'Brien, Eoin; Wang, Jiguang; Staessen, Jan A

2014-05-01

Experts proposed blood pressure (BP) load derived from 24-hour ambulatory BP recordings as a more accurate predictor of outcome than level, in particular in normotensive people. We analyzed 8711 subjects (mean age, 54.8 years; 47.0% women) randomly recruited from 10 populations. We expressed BP load as percentage (%) of systolic/diastolic readings ≥135/≥85 mm Hg and ≥120/≥70 mm Hg during day and night, respectively, or as the area under the BP curve (mm Hg×h) using the same ceiling values. During a period of 10.7 years (median), 1284 participants died and 1109 experienced a fatal or nonfatal cardiovascular end point. In multivariable-adjusted models, the risk of cardiovascular complications gradually increased across deciles of BP level and load (P<0.001), but BP load did not substantially refine risk prediction based on 24-hour systolic or diastolic BP level (generalized R(2) statistic ≤0.294%; net reclassification improvement ≤0.28%; integrated discrimination improvement ≤0.001%). Systolic/diastolic BP load of 40.0/42.3% or 91.8/73.6 mm Hg×h conferred a 10-year risk of a composite cardiovascular end point similar to a 24-hour systolic/diastolic BP of 130/80 mm Hg. In analyses dichotomized according to these thresholds, increased BP load did not refine risk prediction in the whole study population (R(2)≤0.051) or in untreated participants with 24-hour ambulatory normotension (R(2)≤0.034). In conclusion, BP load does not improve risk stratification based on 24-hour BP level. This also applies to subjects with normal 24-hour BP for whom BP load was proposed to be particularly useful in risk stratification.

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.

Characterization of a Murine Pressure Ulcer Model to Assess Efficacy of Adipose-derived Stromal Cells

PubMed Central

Strong, Amy L.; Bowles, Annie C.; MacCrimmon, Connor P.; Lee, Stephen J.; Frazier, Trivia P.; Katz, Adam J.; Gawronska-Kozak, Barbara; Bunnell, Bruce A.

2015-01-01

Background: As the world’s population lives longer, the number of individuals at risk for pressure ulcers will increase considerably in the coming decades. In developed countries, up to 18% of nursing home residents suffer from pressure ulcers and the resulting hospital costs can account for up to 4% of a nation’s health care budget. Although full-thickness surgical skin wounds have been used as a model, preclinical rodent studies have demonstrated that repeated cycles of ischemia and reperfusion created by exposure to magnets most closely mimic the human pressure ulcer condition. Methods: This study uses in vivo and in vitro quantitative parameters to characterize the temporal kinetics and histology of pressure ulcers in young, female C57BL/6 mice exposed to 2 or 3 ischemia-reperfusion cycles. This pressure ulcer model was validated further in studies examining the efficacy of adipose-derived stromal/stem cell administration. Results: Optimal results were obtained with the 2-cycle model based on the wound size, histology, and gene expression profile of representative angiogenic and reparative messenger RNAs. When treated with adipose-derived stromal/stem cells, pressure ulcer wounds displayed a dose-dependent and significant acceleration in wound closure rates and improved tissue histology. Conclusion: These findings document the utility of this simplified preclinical model for the evaluation of novel tissue engineering and medical approaches to treat pressure ulcers in humans. PMID:25878945

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). Copyright © 2015 Elsevier Inc. All rights reserved.

Modelling the pressurization induced by solar radiation on above ground installations of LPG pipeline systems

NASA Astrophysics Data System (ADS)

Leporini, M.; Terenzi, A.; Marchetti, B.; Giacchetta, G.; Polonara, F.; Corvaro, F.; Cocci Grifoni, R.

2017-11-01

Pipelining Liquefied Petroleum Gas (LPG) is a mode of LPG transportation more environmentally-friendly than others due to the lower energy consumption and exhaust emissions. Worldwide, there are over 20000 kilometers of LPG pipelines. There are a number of codes that industry follows for the design, fabrication, construction and operation of liquid LPG pipelines. However, no standards exist to modelling particular critical phenomena which can occur on these lines due to external environmental conditions like the solar radiation pressurization. In fact, the solar radiation can expose above ground pipeline sections at pressure values above the maximum Design Pressure with resulting risks and problems. The present work presents an innovative practice suitable for the Oil & Gas industry to modelling the pressurization induced by the solar radiation on above ground LPG pipeline sections with the application to a real case.

Incidence and Predicted Risk Factors of Pressure Ulcers in Surgical Patients: Experience at a Medical Center in Taipei, Taiwan

PubMed Central

Fu Shaw, Ling; Chang, Pao-Chu; Lee, Jung-Fen; Kung, Huei-Yu

2014-01-01

Purpose. To explore the context of incidence of and associated risk factors for pressure ulcers amongst the population of surgical patients. Methods. The initial study cohort was conducted with a total of 297 patients admitted to a teaching hospital for a surgical operation from November 14th to 27th 2006 in Taipei, Taiwan. The Braden scale, pressure ulcers record sheet, and perioperative patient outcomes free from signs and symptoms of injury related to positioning and related nursing interventions and activities were collected. Results. The incidence of immediate and thirty-minute-later pressure ulcers is 9.8% (29/297) and 5.1% (15/297), respectively. Using logistic regression model, the statistically significantly associated risk factors related to immediate and thirty-minute-later pressure ulcers include operation age, type of anesthesia, type of operation position, type of surgery, admission Braden score, and number of nursing intervention after adjustment for confounding factors. Conclusion. Admission Braden score and number of nursing intervention are well-established protected factors for the development of pressure ulcers. Our study shows that older operation age, type of anesthesia, type of operation position, and type of surgery are also associated with the development of pressure ulcers. PMID:25057484

Modeling pressure rise in gas targets

NASA Astrophysics Data System (ADS)

Jahangiri, P.; Lapi, S. E.; Publicover, J.; Buckley, K.; Martinez, D. M.; Ruth, T. J.; Hoehr, C.

2017-05-01

The purpose of this work is to introduce a universal mathematical model to explain a gas target behaviour at steady-state time scale. To obtain our final goal, an analytical model is proposed to study the pressure rise in the targets used to produce medical isotopes on low-energy cyclotrons. The model is developed based on the assumption that during irradiation the system reaches steady-state. The model is verified by various experiments performed at different beam currents, gas type, and initial pressures at 13 MeV cyclotron at TRIUMF. Excellent agreement is achieved.

Finite element model of size, shape and blood pressure on rupture of intracranial saccular aneurysms

NASA Astrophysics Data System (ADS)

Rica Nabong, Jennica; David, Guido

2017-10-01

Rupture of intracranial saccular aneurysms is a primary concern for neurologists and patients because it leads to stroke and permanent disability. This paper examines the role of blood pressure, in connection with size of and wall thickness, in the rupture of saccular aneurysms. A bulb-shaped geometry of a saccular aneurysm is obtained from angiographic images of a patient and modeled using Finite Elements based on the principle of virtual work under the Fung stress-strain relationship. The numerical model is subjected to varying levels of systolic blood pressure. Rupture is assumed to occur when the wall stress exceeded its mechanical strength. The results show which sizes of this class of aneurysms are at high risk of rupture for varying levels of blood pressure.

Baseline Blood Pressure, the 2017 ACC/AHA High Blood Pressure Guidelines, and Long-Term Cardiovascular Risk in SPRINT.

PubMed

Vaduganathan, Muthiah; Pareek, Manan; Qamar, Arman; Pandey, Ambarish; Olsen, Michael H; Bhatt, Deepak L

2018-02-05

The 2017 American College of Cardiology (ACC)/American Heart Association (AHA) guidelines include lower thresholds to define hypertension than previous guidelines. Little is known about the impact of these guideline changes in patients with or at high risk for cardiovascular disease. In this exploratory analysis using baseline blood pressure assessments in Systolic Blood Pressure Intervention Trial (SPRINT), we evaluated the prevalence and associated cardiovascular prognosis of patients newly reclassified with hypertension based on the 2017 ACC/AHA (systolic blood pressure ≥130 mm Hg or diastolic blood pressure ≥80 mm Hg) compared with the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation and Treatment of High Blood Pressure (JNC 7) guidelines (systolic blood pressure ≥140 mm Hg or diastolic blood pressure ≥90 mm Hg). The primary endpoint was the composite of myocardial infarction, other acute coronary syndromes, stroke, heart failure, or cardiovascular death. In 4683 patients assigned to the standard treatment arm of SPRINT, 2328 (49.7%) met hypertension thresholds by JNC 7 guidelines, and another 1424 (30.4%) were newly reclassified as having hypertension based on the 2017 ACC/AHA guidelines. Over 3.3-year median follow-up, 319 patients experienced the primary endpoint (87 of whom were newly reclassified with hypertension based on the revised guidelines). Patients with hypertension based on prior guidelines compared with those newly identified with hypertension based on the new guidelines had similar risk of the primary endpoint (2.3 [95% confidence interval {CI}, 2.0-2.7] vs 2.0 [95% CI, 1.6-2.4] events per 100 patient-years; adjusted HR, 1.10 [95% CI, 0.84-1.44]; P = .48). The 2017 ACC/AHA high blood pressure guidelines are expected to significantly increase the prevalence of patients with hypertension (perhaps to a greater extent in higher-risk patient cohorts compared with the general population) and

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.

Racial Differences in the Impact of Elevated Systolic Blood Pressure on Stroke Risk

PubMed Central

Howard, George; Lackland, Daniel T.; Kleindorfer, Dawn O.; Kissela, Brett M.; Moy, Claudia S.; Judd, Suzanne E.; Safford, Monika M.; Cushman, Mary; Glasser, Stephen P.; Howard, Virginia J.

2013-01-01

Background Between the ages 45 and 65 years, incident stroke is 2 to 3 times more common in blacks than in whites, a difference not explained by traditional stroke risk factors. Methods Stroke risk was assessed in 27 748 black and white participants recruited between 2003 and 2007, who were followed up through 2011, in the REasons for Geographic And Racial Differences in Stroke (REGARDS) study. Racial differences in the impact of systolic blood pressure (SBP) was assessed using proportional hazards models. Racial differences in stroke risk were assessed in strata defined by age (<65 years, 65–74 years, and ≥75 years) and SBP (<120 mm Hg, 120–139 mm Hg, and 140–159 mm Hg). Results Over 4.5 years of follow-up, 715 incident strokes occurred. A 10–mm Hg difference in SBP was associated with an 8% (95% CI, 0%-16%) increase in stroke risk for whites, but a 24% (95% CI, 14%-35%) increase for blacks (P value for interaction, .02). For participants aged 45 to 64 years (where disparities are greatest), the black to white hazard ratio was 0.87 (95% CI, 0.48–1.57) for normotensive participants, 1.38 (95% CI, 0.94–2.02) for those with prehypertension, and 2.38 (95% CI, 1.19–4.72) for those with stage 1 hypertension. Conclusions These findings suggest racial differences in the impact of elevated blood pressure on stroke risk. When these racial differences are coupled with the previously documented higher prevalence of hypertension and poorer control of hypertension in blacks, they may account for much of the racial disparity in stroke risk. PMID:23229778

The relationship among pressure ulcer risk factors, incidence and nursing documentation in hospital-acquired pressure ulcer patients in intensive care units.

PubMed

Li, Dan

2016-08-01

To explore the quality/comprehensiveness of nursing documentation of pressure ulcers and to investigate the relationship between the nursing documentation and the incidence of pressure ulcers in four intensive care units. Pressure ulcer prevention requires consistent assessments and documentation to decrease pressure ulcer incidence. Currently, most research is focused on devices to prevent pressure ulcers. Studies have rarely considered the relationship among pressure ulcer risk factors, incidence and nursing documentation. Thus, a study to investigate this relationship is needed to fill this information gap. A retrospective, comparative, descriptive, correlational study. A convenience sample of 196 intensive care units patients at the selected medical centre comprised the study sample. All medical records of patients admitted to intensive care units between the time periods of September 1, 2011 through September 30, 2012 were audited. Data used in the analysis included 98 pressure ulcer patients and 98 non-pressure ulcer patients. The quality and comprehensiveness of pressure ulcer documentation were measured by the modified European Pressure Ulcer Advisory Panel Pressure Ulcers Assessment Instrument and the Comprehensiveness in Nursing Documentation instrument. The correlations between quality/comprehensiveness of pressure ulcer documentation and incidence of pressure ulcers were not statistically significant. Patients with pressure ulcers had longer length of stay than patients without pressure ulcers stay. There were no statistically significant differences in quality/comprehensiveness scores of pressure ulcer documentation between dayshift and nightshift. This study revealed a lack of quality/comprehensiveness in nursing documentation of pressure ulcers. This study demonstrates that staff nurses often perform poorly on documenting pressure ulcer appearance, staging and treatment. Moreover, nursing documentation of pressure ulcers does not provide a complete

Incidence and risk factors for surgically acquired pressure ulcers: a prospective cohort study investigators.

PubMed

Webster, Joan; Lister, Carolyn; Corry, Jean; Holland, Michelle; Coleman, Kerrie; Marquart, Louise

2015-01-01

To assess the incidence of hospital-acquired, surgery-related pressure injury (ulcers) and identify risk factors for these injuries. We used a prospective cohort study to investigate the research question. The study was conducted at a major metropolitan hospital in Brisbane, Australia. Five hundred thirty-four adult patients booked for any surgical procedure expected to last more than 30 minutes were eligible for inclusion. Patients who provided informed consent for study participation were assessed for pressure ulcers, using the European Pressure Ulcer Advisory Panel and National Pressure Ulcer Advisory Panel Guidelines, before entering the operating room and again in the post-anesthetic care unit (PACU). Research nurses and all PACU nurses were trained in skin assessment and in pressure ulcer staging. Patients were not assessed again after their discharge from the PACU. Seven patients (1.3%) had existing pressure injuries (ulcers) and a further 6 (1.3%) developed a surgery-related pressure ulcer. Risk factors associated with surgery-related pressure injuries were similar to non-surgically related risks and included older age, skin condition, and being admitted from a location other than one's own home. Length of surgery was not associated with pressure ulcer development in this cohort. Perioperative nurses play an important role in identifying existing or new pressure injuries. However, many of these nurses are unfamiliar with pressure ulcer classification, so education in this area is essential. Although the incidence of surgically acquired pressure ulcers was low in this cohort, careful skin inspection before and after surgery provides an opportunity for early treatment and may prevent existing lesions progressing to higher stages.

Variability of blood pressure in dialysis patients: a new marker of cardiovascular risk.

PubMed

Di Iorio, Biagio; Di Micco, Lucia; Torraca, Serena; Sirico, Maria Luisa; Guastaferro, Pasquale; Chiuchiolo, Luigi; Nigro, Filippo; De Blasio, Antonietta; Romano, Paolo; Pota, Andrea; Rubino, Roberto; Morrone, Luigi; Lopez, Teodoro; Casino, Francesco Gaetano

2013-01-01

Hemodialysis patients have a high cardiovascular mortality, and hypertension is the most prevalent treatable risk factor. We aimed to assess the predictive significance of dialysis-to-dialysis variability in blood pressure in hemodialysis patients. We performed a historical cohort study in 1,088 prevalent hemodialysis patients, followed up for 5 years. The risk of cardiovascular death was determined in relation to dialysis-to-dialysis variability in blood pressure, maximum blood pressure and pulse pressure. Variability in blood pressure was a predictor of cardiovascular death (hazard ratio [HR] = 1.242; 95% confidence interval [95% CI], 1.004-1.537; p=0.046). Also age (HR=1.021; 95% CI, 1.011-1.048; p=0.049), diabetes (HR=1.134; 95% CI, 1.128-1.451; p=0.035), creatinine (HR=0.837; 95% CI, 0.717-0.977; p=0.024) and albumin (HR=0.901; 95% CI, 0.821-0.924; p=0.022) influenced mortality. Maximum blood pressure and pulse pressure did not show any effect on cardiovascular death. Dialysis-to-dialysis variability in blood pressure is a predictor of cardiovascular mortality in hemodialysis patients, and blood pressure variability may be used in managing hypertension and predicting outcomes in dialysis patients.

Systolic blood pressure, diabetes and the risk of cardiovascular diseases in the Asia-Pacific region.

PubMed

Kengne, A P; Patel, A; Barzi, F; Jamrozik, K; Lam, T H; Ueshima, H; Gu, D F; Suh, I; Woodward, M

2007-06-01

To assess the association between systolic blood pressure (SBP) and cardiovascular diseases (CVD) among participants with and without diabetes from cohorts in the Asia-Pacific region. Hazards ratios and 95% confidence intervals (CI) for CVD were calculated from Cox models, stratified by sex and region and adjusted for age using individual participant data from 36 cohort studies. Repeat measurements of SBP were used to adjust for regression dilution bias. During follow-up, 7387 fatal or non-fatal cardiovascular endpoints were recorded among 368 307 participants (6.4% with diabetes). SBP was associated with coronary heart disease (CHD), ischaemic stroke and haemorrhagic stroke in a continuous log-linear fashion among individuals with diabetes, as well as those without diabetes. Overall, each 10 mmHg higher usual SBP was associated with 18% (95% CI: 9-27%) and 23% (19-26%) greater risk for CHD among those with and without diabetes, respectively. The corresponding values for ischaemic stroke were 29% (14-45%) and 43% (37-50%), and for haemorrhagic stroke, 56% (32-83%) and 74% (66-82%). The test for heterogeneity by diabetes status in each of these associations was not significant (P >or= 0.10). Systolic blood pressure is an important marker of risk of CVD in people with and without diabetes. A given reduction in systolic blood pressure is likely to have a similar relative effect on reducing the risk of a cardiovascular event, regardless of diabetes status.

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.

Pressure in an exactly solvable model of active fluid

NASA Astrophysics Data System (ADS)

Marini Bettolo Marconi, Umberto; Maggi, Claudio; Paoluzzi, Matteo

2017-07-01

We consider the pressure in the steady-state regime of three stochastic models characterized by self-propulsion and persistent motion and widely employed to describe the behavior of active particles, namely, the Active Brownian particle (ABP) model, the Gaussian colored noise (GCN) model, and the unified colored noise approximation (UCNA) model. Whereas in the limit of short but finite persistence time, the pressure in the UCNA model can be obtained by different methods which have an analog in equilibrium systems, in the remaining two models only the virial route is, in general, possible. According to this method, notwithstanding each model obeys its own specific microscopic law of evolution, the pressure displays a certain universal behavior. For generic interparticle and confining potentials, we derive a formula which establishes a correspondence between the GCN and the UCNA pressures. In order to provide explicit formulas and examples, we specialize the discussion to the case of an assembly of elastic dumbbells confined to a parabolic well. By employing the UCNA we find that, for this model, the pressure determined by the thermodynamic method coincides with the pressures obtained by the virial and mechanical methods. The three methods when applied to the GCN give a pressure identical to that obtained via the UCNA. Finally, we find that the ABP virial pressure exactly agrees with the UCNA and GCN results.

Racial and gender discrimination: risk factors for high blood pressure?

PubMed

Krieger, N

1990-01-01

Despite controversy as to the biologic and/or social meaning of 'race' and 'sex', few public health studies have directly examined the impact of racial or gender discrimination on health. One plausible condition they might affect is hypertension, since stress and internalized anger may constitute important risk factors for this disease. The present investigation therefore sought to determine the feasibility of asking questions pertaining to race- and gender-biased treatment plus response to unfair treatment, and to assess their predictive value regarding self-reported high blood pressure. Using random-digit dialing, 51 black and 50 white women, ages 20-80, who resided in Alameda County, CA in 1987, were identified and interviewed by phone. Among black respondents, those who stated they usually accepted and kept quiet about unfair treatment were 4.4 times more likely to report hypertension than women who said they took action and talked to others (P = 0.01 for linear trend); no clear association existed among white respondents. The age-adjusted risk of high blood pressure among black respondents who recounted experiencing zero instances of race- and gender-biased treatment was 2.6 times greater than that of black women who reported one or more such instances (95% CI = 0.7, 10.5). Among white respondents, gender discrimination was not associated with hypertension. These results suggest that an internalized response to unfair treatment, plus non-reporting of race and gender discrimination, may constitute risk factors for high blood pressure among black women. They also bolster the view that subjective appraisal of stressors may be inversely associated with risk of hypertension.

Alternative Strategies to Achieve Cardiovascular Mortality Goals in China and India: A Microsimulation of Target- Versus Risk-Based Blood Pressure Treatment.

PubMed

Basu, Sanjay; Yudkin, John S; Sussman, Jeremy B; Millett, Christopher; Hayward, Rodney A

2016-03-01

The World Health Organization aims to reduce mortality from chronic diseases including cardiovascular disease (CVD) by 25% by 2025. High blood pressure is a leading CVD risk factor. We sought to compare 3 strategies for treating blood pressure in China and India: a treat-to-target (TTT) strategy emphasizing lowering blood pressure to a target, a benefit-based tailored treatment (BTT) strategy emphasizing lowering CVD risk, or a hybrid strategy currently recommended by the World Health Organization. We developed a microsimulation model of adults aged 30 to 70 years in China and in India to compare the 2 treatment approaches across a 10-year policy-planning horizon. In the model, a BTT strategy treating adults with a 10-year CVD event risk of ≥ 10% used similar financial resources but averted ≈ 5 million more disability-adjusted life-years in both China and India than a TTT approach based on current US guidelines. The hybrid strategy in the current World Health Organization guidelines produced no substantial benefits over TTT. BTT was more cost-effective at $205 to $272/disability-adjusted life-year averted, which was $142 to $182 less per disability-adjusted life-year than TTT or hybrid strategies. The comparative effectiveness of BTT was robust to uncertainties in CVD risk estimation and to variations in the age range analyzed, the BTT treatment threshold, or rates of treatment access, adherence, or concurrent statin therapy. In model-based analyses, a simple BTT strategy was more effective and cost-effective than TTT or hybrid strategies in reducing mortality. © 2016 American Heart Association, Inc.

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.

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

... Pressure Testing § 195.303 Risk-based alternative to pressure testing older hazardous liquid and carbon... 49 Transportation 3 2014-10-01 2014-10-01 false Risk-based alternative to pressure testing older hazardous liquid and carbon dioxide pipelines. 195.303 Section 195.303 Transportation Other Regulations...

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

Code of Federal Regulations, 2013 CFR

2013-10-01

... Pressure Testing § 195.303 Risk-based alternative to pressure testing older hazardous liquid and carbon... 49 Transportation 3 2013-10-01 2013-10-01 false Risk-based alternative to pressure testing older hazardous liquid and carbon dioxide pipelines. 195.303 Section 195.303 Transportation Other Regulations...

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

... Pressure Testing § 195.303 Risk-based alternative to pressure testing older hazardous liquid and carbon... 49 Transportation 3 2012-10-01 2012-10-01 false Risk-based alternative to pressure testing older hazardous liquid and carbon dioxide pipelines. 195.303 Section 195.303 Transportation Other Regulations...

Linking family economic pressure and supportive parenting to adolescent health behaviors: two developmental pathways leading to health promoting and health risk behaviors.

PubMed

Kwon, Josephine A; Wickrama, K A S

2014-07-01

Adolescent health behaviors, especially health risk behaviors, have previously been linked to distal (i.e., family economic pressure) and proximal (i.e., parental support) contributors. However, few studies have examined both types of contributors along with considering health promoting and health risk behaviors separately. The present study investigated the influences of family economic hardship, supportive parenting as conceptualized by self-determination theory, and individual psychosocial and behavioral characteristics (i.e., mastery and delinquency, respectively) on adolescents' health promoting and health risk behaviors. We used structural equation modeling to analyze longitudinal data from a sample of Caucasian adolescent children and their mothers and fathers (N = 407, 54 % female) to examine direct and indirect effects, as well as gender symmetry and asymmetry. Findings suggest that family economic pressure contributed to adolescent mastery and delinquency through supportive parenting. Further, supportive parenting indirectly affected adolescent health risk behaviors only through delinquency, whereas supportive parenting indirectly influenced health promoting behaviors only through mastery, suggesting different developmental pathways for adolescent health risk and health promoting behaviors. Testing for gender symmetry of the full model showed that maternal and paternal parenting contributed to females' health risk behaviors directly, while maternal and paternal parenting contributed to males' health risk behaviors through delinquency. Gender symmetry was largely unsupported. The study highlights key direct and indirect pathways to adolescent health risk and health promoting behaviors within a family stress model and self-determination theory framework, and also highlights important gender differences in these developmental pathways.

Effect of e-learning program on risk assessment and pressure ulcer classification - A randomized study.

PubMed

Bredesen, Ida Marie; Bjøro, Karen; Gunningberg, Lena; Hofoss, Dag

2016-05-01

Pressure ulcers (PUs) are a problem in health care. Staff competency is paramount to PU prevention. Education is essential to increase skills in pressure ulcer classification and risk assessment. Currently, no pressure ulcer learning programs are available in Norwegian. Develop and test an e-learning program for assessment of pressure ulcer risk and pressure ulcer classification. Forty-four nurses working in acute care hospital wards or nursing homes participated and were assigned randomly into two groups: an e-learning program group (intervention) and a traditional classroom lecture group (control). Data was collected immediately before and after training, and again after three months. The study was conducted at one nursing home and two hospitals between May and December 2012. Accuracy of risk assessment (five patient cases) and pressure ulcer classification (40 photos [normal skin, pressure ulcer categories I-IV] split in two sets) were measured by comparing nurse evaluations in each of the two groups to a pre-established standard based on ratings by experts in pressure ulcer classification and risk assessment. Inter-rater reliability was measured by exact percent agreement and multi-rater Fleiss kappa. A Mann-Whitney U test was used for continuous sum score variables. An e-learning program did not improve Braden subscale scoring. For pressure ulcer classification, however, the intervention group scored significantly higher than the control group on several of the categories in post-test immediately after training. However, after three months there were no significant differences in classification skills between the groups. An e-learning program appears to have a greater effect on the accuracy of pressure ulcer classification than classroom teaching in the short term. For proficiency in Braden scoring, no significant effect of educational methods on learning results was detected. Copyright © 2016 Elsevier Ltd. All rights reserved.

Quantifying risk of death and disability associated with raised blood pressure.

PubMed

Elliott, P; Nichols, R; Chee, D

1999-01-01

Raised blood pressure is one of the most important underlying risk factors for morbidity and mortality in the world today, ranking alongside tobacco in estimates of the worldwide attributable burden of mortality. It is a major risk factor for coronary heart disease and the major risk factor for stroke. Taken together, the cardiovascular diseases are estimated to account for some 28% of all deaths in the world. Already many more of such deaths are occurring in the developing than the developed world, and this burden of disease is set to worsen as a result of demographic changes in the poorer countries, together with adoption of Western lifestyle. The development of unfavourable blood pressure patterns in populations is a key factor underlying this worldwide epidemic. Both primary prevention (for example through improved diet) and secondary prevention (through drug treatment and non-pharmacologic approaches) are needed.

Using the Care Dependency Scale for identifying patients at risk for pressure ulcer.

PubMed

Dijkstra, Ate; Kazimier, Hetty; Halfens, Ruud J G

2015-11-01

The aim of this study was to evaluate risk screening for pressure ulcer by using the Care Dependency Scale (CDS) for patients receiving home care or admitted to a residential or nursing home in the Netherlands. Pressure ulcer is a serious and persistent problem for patients throughout the Western world. Pressure ulcer is among the most common adverse events in nursing practice and when a pressure ulcer occurs it has many consequences for patients and healthcare professionals. Cross-sectional design. The convenience sample consisted of 13,633 study participants, of whom 2639 received home care from 15 organisations, 4077 were patients from 67 residential homes and 6917 were admitted in 105 nursing homes. Data were taken from the Dutch National Prevalence Survey of Care Problems that was carried out in April 2012 in Dutch healthcare settings. For the three settings, cut-off points above 80% sensitivity were established, while in the residential home sample an almost 60% combined specificity score was identified. The CDS items 'Body posture' (home care), 'Getting dressed and undressed' (residential homes) and 'Mobility' (nursing homes) were the most significant variables which affect PU. The CDS is able to distinguish between patients at risk for pressure ulcer development and those not at risk in both home care and residential care settings. In nursing homes, the usefulness of the CDS for pressure ulcer detection is limited. © 2015 John Wiley & Sons Ltd.

Adverse risk: a 'dynamic interaction model of patient moving and handling'.

PubMed

Griffiths, Howard

2012-09-01

The aim of the present study was to examine patient adverse events associated with sub-optimal patient moving and handling. Few studies have examined the patient's perspective on adverse risk during manual handling episodes. A narrative review was undertaken to develop the 'Dynamic Interaction Model of Patient Moving and Handling' in an orthopaedic rehabilitation setting, using peer-reviewed publications published in English between 1992 and 2010. Five predominant themes emerged from the narrative review: 'patient's need to know about analgesics prior to movement/ambulation'; 'comfort care'; 'mastery of and acceptance of mobility aids/equipment'; 'psychological adjustment to fear of falling'; and 'the need for movement to prevent tissue pressure damage'. Prevalence of discomfort, pain, falls, pressure sores together with a specific Direct Instrument Nursing Observation (DINO) tool enable back care advisers to measure quality of patient manual handling. Evaluation of patients' use of mobility aids together with fear of falling may be important in determining patients' recovery trajectory. Clinical governance places a responsibility on nurse managers to consider quality of care for their service users. 'Dynamic Interaction Model of Nurse-Patient Moving and Handling' provides back care advisers, clinical risk managers and occupational health managers with an alternative perspective to clinical risk and occupational risk. © 2011 Blackwell Publishing Ltd.

Depression and blood pressure in high-risk children and adolescents: an investigation using two longitudinal cohorts

PubMed Central

Hammerton, Gemma; Harold, Gordon; Thapar, Anita; Thapar, Ajay

2013-01-01

Objective To examine the relationship between blood pressure and depressive disorder in children and adolescents at high risk for depression. Design Multisample longitudinal design including a prospective longitudinal three-wave high-risk study of offspring of parents with recurrent depression and an on-going birth cohort for replication. Setting Community-based studies. Participants High-risk sample includes 281 families where children were aged 9–17 years at baseline and 10–19 years at the final data point. Replication cohort includes 4830 families where children were aged 11–14 years at baseline and 14–17 years at follow-up and a high-risk subsample of 612 offspring with mothers that had reported recurrent depression. Main outcome measures The new-onset of Diagnostic and Statistical Manual of Mental Disorder, fourth edition defined depressive disorder in the offspring using established research diagnostic assessments—the Child and Adolescent Psychiatric Assessment in the high-risk sample and the Development and Wellbeing Assessment in the replication sample. Results Blood pressure was standardised for age and gender to create SD scores and child's weight was statistically controlled in all analyses. In the high-risk sample, lower systolic blood pressure at wave 1 significantly predicted new-onset depressive disorder in children (OR=0.65, 95% CI 0.44 to 0.96; p=0.029) but diastolic blood pressure did not. Depressive disorder at wave 1 did not predict systolic blood pressure at wave 3. A significant association between lower systolic blood pressure and future depression was also found in the replication cohort in the second subset of high-risk children whose mothers had experienced recurrent depression in the past. Conclusions Lower systolic blood pressure predicts new-onset depressive disorder in the offspring of parents with depression. Further studies are needed to investigate how this association arises. PMID:24071459

Association Between Blood Pressure Control and Risk of Recurrent Intracerebral Hemorrhage.

PubMed

Biffi, Alessandro; Anderson, Christopher D; Battey, Thomas W K; Ayres, Alison M; Greenberg, Steven M; Viswanathan, Anand; Rosand, Jonathan

2015-09-01

Intracerebral hemorrhage (ICH) is the most severe form of stroke. Survivors are at high risk of recurrence, death, and worsening functional disability. To investigate the association between blood pressure (BP) after index ICH and risk of recurrent ICH. Single-site, tertiary care referral center observational study of 1145 of 2197 consecutive patients with ICH presenting from July 1994 to December 2013. A total of 1145 patients with ICH survived at least 90 days and were followed up through December 2013 (median follow-up of 36.8 months [minimum, 9.8 months]). Blood pressure measurements at 3, 6, 9, and 12 months, and every 6 months thereafter, obtained from medical personnel (inpatient hospital or outpatient clinic medical or nursing staff) or via patient self-report. Exposure was characterized in 3 ways: (1) recorded systolic and diastolic measurements; (2) classification as adequate or inadequate BP control based on American Heart Association/American Stroke Association recommendations; and (3) stage of hypertension based on Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure 7 criteria. Recurrent ICH and its location within the brain (lobar vs nonlobar). There were 102 recurrent ICH events among 505 survivors of lobar ICH and 44 recurrent ICH events among 640 survivors of nonlobar ICH. During follow-up adequate BP control was achieved on at least 1 measurement by 625 patients (54.6% of total [range, 49.2%-58.7%]) and consistently (ie, at all available time points) by 495 patients (43.2% of total [range, 34.5%-51.0%]). The event rate for lobar ICH was 84 per 1000 person-years among patients with inadequate BP control compared with 49 per 1000 person-years among patients with adequate BP control. For nonlobar ICH the event rate was 52 per 1000 person-years with inadequate BP control compared with 27 per 1000 person-years for patients with adequate BP control. In analyses modeling BP control as a time

Local plantar pressure relief in therapeutic footwear: design guidelines from finite element models.

PubMed

Erdemir, Ahmet; Saucerman, Jeffrey J; Lemmon, David; Loppnow, Bryan; Turso, Brie; Ulbrecht, Jan S; Cavanagh, Peter Re

2005-09-01

A major goal of therapeutic footwear in patients with pain or those at risk for skin injury is to relieve focal loading under prominent metatarsal heads. One frequent approach is to place plugs of compliant material into the midsole of the shoe. This study investigated 36 plug designs, a combination of three materials, six geometries, and two placements using a two-dimensional (2D) finite element model. Realistic loading conditions were obtained from plantar pressures (PP) recorded during walking in five subjects who wore control midsoles manufactured using Microcell Puff. Measured peak pressures underneath the second metatarsal head were similar to the results of the control model. PP obtained from simulations with the plugs built into a firm midsole were compared to the simulation results of the control midsole. Large plugs (e.g. 40 mm width), made out of Microcell Puff Lite or Plastazote Medium, placed at peak pressure sites, resulted in highest reductions in peak pressures (18-28%). Smaller plugs benefited from tapering when placed at high pressure areas. Case studies were completed on a healthy male subject and a diabetic female patient to address the efficacy of a plug design favored by our simulations (pressure based placement, 40 x 20 mm, Plastazote Medium). Successful reductions of second metatarsal head pressures were observed with a mediolateral load redistribution that was not represented by our model. 2D computer simulations allowed systematic investigation of plug properties without the need for high volume experimentation on human subjects and established basic guidelines for plug selection. In particular, plugs that are placed based on plantar pressure measurements were proven to be more effective when compared to those positioned according to the projection of the bony landmark on the foot-shoe plantar contact area.

Effect of non-linear fluid pressure diffusion on modeling induced seismicity during reservoir stimulation

NASA Astrophysics Data System (ADS)

Gischig, V.; Goertz-Allmann, B. P.; Bachmann, C. E.; Wiemer, S.

2012-04-01

Success of future enhanced geothermal systems relies on an appropriate pre-estimate of seismic risk associated with fluid injection at high pressure. A forward-model based on a semi-stochastic approach was created, which is able to compute synthetic earthquake catalogues. It proved to be able to reproduce characteristics of the seismic cloud detected during the geothermal project in Basel (Switzerland), such as radial dependence of stress drop and b-values as well as higher probability of large magnitude earthquakes (M>3) after shut-in. The modeling strategy relies on a simplistic fluid pressure model used to trigger failure points (so-called seeds) that are randomly distributed around an injection well. The seed points are assigned principal stress magnitudes drawn from Gaussian distributions representative of the ambient stress field. Once the effective stress state at a seed point meets a pre-defined Mohr-Coulomb failure criterion due to a fluid pressure increase a seismic event is induced. We assume a negative linear relationship between b-values and differential stress. Thus, for each event a magnitude can be drawn from a Gutenberg-Richter distribution with a b-value corresponding to differential stress at failure. The result is a seismic cloud evolving in time and space. Triggering of seismic events depends on appropriately calculating the transient fluid pressure field. Hence an effective continuum reservoir model able to reasonably reproduce the hydraulic behavior of the reservoir during stimulation is required. While analytical solutions for pressure diffusion are computationally efficient, they rely on linear pressure diffusion with constant hydraulic parameters, and only consider well head pressure while neglecting fluid injection rate. They cannot be considered appropriate in a stimulation experiment where permeability irreversibly increases by orders of magnitude during injection. We here suggest a numerical continuum model of non-linear pressure

The J-curve between Diastolic Blood Pressure and Risk of All-cause and Cardiovascular Death.

PubMed

Kimm, Heejin; Mok, Yejin; Lee, Sun Ju; Lee, Sunmi; Back, Joung Hwan; Jee, Sun Ha

2018-01-01

The J-curve phenomenon between diastolic blood pressure (DBP) and mortality has been reported repeatedly in treated patients. However, the baseline risk of low DBP has not been fully explored. This study was to examine the relationship between DBP and risk of mortality from all-cause, atherosclerotic vascular diseases (ASCVD), and ischemic heart disease (IHD) using a prospective cohort of general population. We analyzed 1,234,435 participants of the Korean Cancer Prevention Study cohort (789,255 men, 30-95 years of age) who had a medical evaluation from 1992 to 1995 using Cox proportional hazards models. A total of 22.5 million person-years were followed up (mean age 46.6 years, deaths 193,903 cases). The hazard ratios of mortality from all-cause and ASCVD, among those with DBP <60 mmHg compared to 70-79 mmHg were 1.23 (95% confidence interval [CI], 1.16-1.30) and 1.37 (95% CI, 1.20-1.57), respectively, after adjustment for multivariable including systolic blood pressure. Increased risks of all-cause death in the lowest DBP category group were maintained in men or women, 30-59 or ≥60 years of age, smoker or non-smoker and diabetes mellitus (DM) or non-DM subgroups. The risk in DBP 60-69 mmHg groups increased in several subgroups. However, the risk for ASCVD death in 30-59 years and DM group, and risk for IHD death in most subgroups except for elderly (≥60 years) decreased. A J-curve relationship between low DBP and all-cause death was found consistently. The baseline risk in the general population may be considered for risk assessment, particularly in case of interventions that lower DBP below 60 mmHg. Copyright © 2018. The Korean Society of Cardiology

Risk Factors for Pressure Ulcers Including Suspected Deep Tissue Injury in Nursing Home Facility Residents: Analysis of National Minimum Data Set 3.0.

PubMed

Ahn, Hyochol; Cowan, Linda; Garvan, Cynthia; Lyon, Debra; Stechmiller, Joyce

2016-04-01

To provide information on risk factors associated with pressure ulcers (PrUs), including suspected deep tissue injury (sDTI), in nursing home residents in the United States. This continuing education activity is intended for physicians and nurses with an interest in skin and wound care. After participating in this educational activity, the participant should be better able to:1. Examine the literature related to risk factors for the development of PrUs.2. Compare risk factors associated with the prevalence of PrUs and sDTI from the revised Minimum Data Set 3.0 2012 using a modified Defloor's conceptual model of PrUs as a theoretical framework. This study aims to characterize and compare risk factors associated with pressure ulcers (PrUs), including suspected deep tissue injury (sDTI), in nursing home (NH) residents in the United States. Secondary analysis of the 2012 Minimum Data Set (MDS 3.0). Medicare- or Medicaid-certified NHs in the United States. Nursing home residents (n = 2,936,146) 18 years or older with complete PrU data, who received comprehensive assessments from January to December 2012. Pressure ulcer by stage was the outcome variable. Explanatory variables (age, gender, race and ethnicity, body mass index, skin integrity, system failure, disease, infection, mobility, and cognition) from the MDS 3.0 were aligned with the 4 elements of Defloor's conceptual model: compressive forces, shearing forces, tissue tolerance for pressure, and tissue tolerance for oxygen. Of 2,936,146 NH residents who had complete data for PrU, 89.9% had no PrU; 8.4% had a Stage 2, 3, or 4 or unstagable PrU; and 1.7% had an sDTI. The MDS variables corresponding to the 4 elements of Defloor's model were significantly predictive of both PrU and sDTI. Black residents had the highest risk of any-stage PrU, and Hispanic residents had the highest risk of sDTI. Skin integrity, system failure, infection, and disease risk factors had larger effect sizes for sDTI than for other PrU stages

Risk assessment and remedial policy evaluation using predictive modeling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Linkov, L.; Schell, W.R.

1996-06-01

As a result of nuclear industry operation and accidents, large areas of natural ecosystems have been contaminated by radionuclides and toxic metals. Extensive societal pressure has been exerted to decrease the radiation dose to the population and to the environment. Thus, in making abatement and remediation policy decisions, not only economic costs but also human and environmental risk assessments are desired. This paper introduces a general framework for risk assessment and remedial policy evaluation using predictive modeling. Ecological risk assessment requires evaluation of the radionuclide distribution in ecosystems. The FORESTPATH model is used for predicting the radionuclide fate in forestmore » compartments after deposition as well as for evaluating the efficiency of remedial policies. Time of intervention and radionuclide deposition profile was predicted as being crucial for the remediation efficiency. Risk assessment conducted for a critical group of forest users in Belarus shows that consumption of forest products (berries and mushrooms) leads to about 0.004% risk of a fatal cancer annually. Cost-benefit analysis for forest cleanup suggests that complete removal of organic layer is too expensive for application in Belarus and a better methodology is required. In conclusion, FORESTPATH modeling framework could have wide applications in environmental remediation of radionuclides and toxic metals as well as in dose reconstruction and, risk-assessment.« less

Pressure mapping to assess seated pressure distributions and the potential risk for skin ulceration in a population of sledge hockey players and control subjects.

PubMed

Berthold, Justin; Dicianno, Brad E; Cooper, Rory A

2013-09-01

Ice sledge (or sled) hockey is a fast-paced sport that enables individuals with physical disabilities to play ice hockey. As the attraction to the sport continues to rise, the need for developing better equipment and installing preventative measures for injury will become increasingly important. One such injury includes skin pressure ulceration. A total of 26 subjects including active controls and those with spinal cord injury, multiple sclerosis, limb amputation and traumatic brain injury were studied using a pressure mapping device at the 2012 National Disabled Veterans Winter Sports Clinic to determine the risk for skin pressure ulceration and the impact of cushioning and knee angle positioning on seated pressure distributions. Sledge hockey athletes may be at increased risk for skin pressure ulceration based on seated pressure distribution data. This experiment failed to demonstrate a benefit for specialty cushioning in either group. Interestingly, knee angle positioning, particularly, knee extension significantly lowered the average seated pressures. When considering the risk for skin pressure ulceration, knee angle positioning is of particular clinical importance. More research is warranted, specifically targeting novel cushion and sledge designs and larger groups of individuals with sensory loss and severe spinal deformities. Implications for Rehabilitation Ice sledge (or sled) hockey is a fast-paced and growing adaptive sport played at the Paralympic level. Rehabilitation professionals should consider the potential for skin ulceration in this population of athletes. The effects of cushioning used in the sledge design warrants further investigation. Knee angle positioning; particularly, knee extension significantly lowers seated pressures and may reduce the potential for skin ulceration.

More Young Adults at Risk for High Blood Pressure | NIH MedlinePlus the Magazine

MedlinePlus

... young adults have high blood pressure. NIH-funded analysis indicates higher risk for young adults than previously ... DASH) clinical study, which tested the effects of food nutrients on blood pressure. It emphasizes consumption of ...

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.

The incidence of pressure ulcer in patients on mechanical ventilation andeffects of selected risk factors on pressure ulcer development.

PubMed

Karayurt, Özgül; Akyol, Özay; Kılıçaslan, Necmiye; Akgün, Nuray; Sargın, Ümran; Kondakçı, Melike; Ekinci, Hanım; Sarı, Neslihan

2016-11-17

This study aimed to determine the incidence of pressure ulcers in patients on mechanical ventilation and selected risk factors likely to play a role in pressure ulcer development. The study included 110 patients recruited from an anesthesia critical care unit of a university hospital. Data were collected with a demographic and clinical characteristics form. The form was composed of questions about demographic characteristics and clinical features including diagnosis, duration of mechanical ventilation, general well-being, oxygenation, perfusion, and skin condition. The incidence of pressure ulcer was 15.5%. Duration of mechanical ventilation was longer and the body mass index was higher in patients developing pressure ulcers than in those without pressure ulcers. Additionally, 90.11% of patients with pressure ulcers had edema and 82.35% of patients with pressure ulcers received vasopressin. The patients with pressure ulcers had higher PH levels, lower PaO2 levels, higher PCO2 levels, lower SaO2 levels, and higher urine output. It can be recommended that nurses and other health professionals should be aware of factors playing a role in pressure ulcer development and should be able to conduct appropriate interventions to prevent pressure ulcers.

Assessing Predictive Validity of Pressure Ulcer Risk Scales- A Systematic Review and Meta-Analysis

PubMed Central

PARK, Seong-Hi; LEE, Hea Shoon

2016-01-01

Background: The purpose of this study was to present a scientific reason for pressure ulcer risk scales: Cubbin& Jackson modified Braden, Norton, and Waterlow, as a nursing diagnosis tool by utilizing predictive validity of pressure sores. Methods: Articles published between 1966 and 2013 from periodicals indexed in the Ovid Medline, Embase, CINAHL, KoreaMed, NDSL, and other databases were selected using the key word “pressure ulcer”. QUADAS-II was applied for assessment for internal validity of the diagnostic studies. Selected studies were analyzed using meta-analysis with MetaDisc 1.4. Results: Seventeen diagnostic studies with high methodological quality, involving 5,185 patients, were included. In the results of the meta-analysis, sROC AUC of Braden, Norton, and Waterflow scale was over 0.7, showing moderate predictive validity, but they have limited interpretation due to significant differences between studies. In addition, Waterlow scale is insufficient as a screening tool owing to low sensitivity compared with other scales. Conclusion: The contemporary pressure ulcer risk scale is not suitable for uninform practice on patients under standardized criteria. Therefore, in order to provide more effective nursing care for bedsores, a new or modified pressure ulcer risk scale should be developed upon strength and weaknesses of existing tools. PMID:27114977

Significant interarm blood pressure difference predicts cardiovascular risk in hypertensive patients

PubMed Central

Kim, Su-A; Kim, Jang Young; Park, Jeong Bae

2016-01-01

Abstract There has been a rising interest in interarm blood pressure difference (IAD), due to its relationship with peripheral arterial disease and its possible relationship with cardiovascular disease. This study aimed to characterize hypertensive patients with a significant IAD in relation to cardiovascular risk. A total of 3699 patients (mean age, 61 ± 11 years) were prospectively enrolled in the study. Blood pressure (BP) was measured simultaneously in both arms 3 times using an automated cuff-oscillometric device. IAD was defined as the absolute difference in averaged BPs between the left and right arm, and an IAD ≥ 10 mm Hg was considered to be significant. The Framingham risk score was used to calculate the 10-year cardiovascular risk. The mean systolic IAD (sIAD) was 4.3 ± 4.1 mm Hg, and 285 (7.7%) patients showed significant sIAD. Patients with significant sIAD showed larger body mass index (P < 0.001), greater systolic BP (P = 0.050), more coronary artery disease (relative risk = 1.356, P = 0.034), and more cerebrovascular disease (relative risk = 1.521, P = 0.072). The mean 10-year cardiovascular risk was 9.3 ± 7.7%. By multiple regression, sIAD was significantly but weakly correlated with the 10-year cardiovascular risk (β = 0.135, P = 0.008). Patients with significant sIAD showed a higher prevalence of coronary artery disease, as well as an increase in 10-year cardiovascular risk. Therefore, accurate measurements of sIAD may serve as a simple and cost-effective tool for predicting cardiovascular risk in clinical settings. PMID:27310982

Computer model analysis of the radial artery pressure waveform.

PubMed

Schwid, H A; Taylor, L A; Smith, N T

1987-10-01

Simultaneous measurements of aortic and radial artery pressures are reviewed, and a model of the cardiovascular system is presented. The model is based on resonant networks for the aorta and axillo-brachial-radial arterial system. The model chosen is a simple one, in order to make interpretation of the observed relationships clear. Despite its simplicity, the model produces realistic aortic and radial artery pressure waveforms. It demonstrates that the resonant properties of the arterial wall significantly alter the pressure waveform as it is propagated from the aorta to the radial artery. Although the mean and end-diastolic radial pressures are usually accurate estimates of the corresponding aortic pressures, the systolic pressure at the radial artery is often much higher than that of the aorta due to overshoot caused by the resonant behavior of the radial artery. The radial artery dicrotic notch is predominantly dependent on the axillo-brachial-radial arterial wall properties, rather than on the aortic valve or peripheral resistance. Hence the use of the radial artery dicrotic notch as an estimate of end systole is unreliable. The rate of systolic upstroke, dP/dt, of the radial artery waveform is a function of many factors, making it difficult to interpret. The radial artery waveform usually provides accurate estimates for mean and diastolic aortic pressures; for all other measurements it is an inadequate substitute for the aortic pressure waveform. In the presence of low forearm peripheral resistance the mean radial artery pressure may significantly underestimate the mean aortic pressure, as explained by a voltage divider model.

Effect of Elevated Reperfusion Pressure on "No Reflow" Area and Infarct Size in a Porcine Model of Ischemia-Reperfusion.

PubMed

Pantsios, Chris; Kapelios, Chris; Vakrou, Styliani; Diakos, Nikolaos; Pozios, Iraklis; Kontogiannis, Chris; Nanas, John; Malliaras, Konstantinos

2016-07-01

The "no reflow" phenomenon (microvascular obstruction despite restoration of epicardial blood flow) develops postreperfusion in acute myocardial infarction and is associated with poor prognosis. We hypothesized that increased reperfusion pressure may attenuate the no reflow phenomenon, as it could provide adequate flow to overcome the high resistance of the microvasculature within the no reflow zone. Thus, we investigated the effect of modestly elevated blood pressure during reperfusion on the extent of no reflow area and infarct size in a porcine model of ischemia-reperfusion. Eighteen farm pigs underwent acute myocardial infarction by occlusion of the anterior descending coronary artery for 1 hour, followed by 2 hours of reperfusion. Just prior to reperfusion, animals were randomized into 2 groups: in group 1 (control group, n = 9), no intervention was performed. In group 2 (n = 9), aortic pressure was increased by ∼20% (compared to ischemia) by partial clamping of the ascending aorta during reperfusion. Following 2 hours of reperfusion, animals were euthanized to measure area at risk, infarct size, and area of no reflow. Partial clamping of the ascending aorta resulted in modest elevation of blood pressure during reperfusion. The area at risk did not differ between the 2 groups. The no reflow area was significantly increased in group 2 compared to control animals (50% ± 13% vs 37% ± 9% of the area at risk; P = .04). The infarcted area was significantly increased in group 2 compared to control animals (75% ± 17% vs 52% ± 23% of the area at risk; P = .03). Significant positive correlations were observed between systolic aortic pressure and no reflow area, between systolic aortic pressure and infarcted area and between infarcted area and no reflow area during reperfusion. Modestly elevated blood pressure during reperfusion is associated with an increase in no reflow area and in infarct size in a clinically relevant porcine model of ischemia-reperfusion. �

A human cadaver fascial compartment pressure measurement model.

PubMed

Messina, Frank C; Cooper, Dylan; Huffman, Gretchen; Bartkus, Edward; Wilbur, Lee

2013-10-01

Fresh human cadavers provide an effective model for procedural training. Currently, there are no realistic models to teach fascial compartment pressure measurement. We created a human cadaver fascial compartment pressure measurement model and studied its feasibility with a pre-post design. Three faculty members, following instructions from a common procedure textbook, used a standard handheld intra-compartment pressure monitor (Stryker(®), Kalamazoo, MI) to measure baseline pressures ("unembalmed") in the anterior, lateral, deep posterior, and superficial posterior compartments of the lower legs of a fresh human cadaver. The right femoral artery was then identified by superficial dissection, cannulated distally towards the lower leg, and connected to a standard embalming machine. After a 5-min infusion, the same three faculty members re-measured pressures ("embalmed") of the same compartments on the cannulated right leg. Unembalmed and embalmed readings for each compartment, and baseline readings for each leg, were compared using a two-sided paired t-test. The mean baseline compartment pressures did not differ between the right and left legs. Using the embalming machine, compartment pressure readings increased significantly over baseline for three of four fascial compartments; all in mm Hg (±SD): anterior from 40 (±9) to 143 (±44) (p = 0.08); lateral from 22 (±2.5) to 160 (±4.3) (p < 0.01); deep posterior from 34 (±7.9) to 161 (±15) (p < 0.01); superficial posterior from 33 (±0) to 140 (±13) (p < 0.01). We created a novel and measurable fascial compartment pressure measurement model in a fresh human cadaver using a standard embalming machine. Set-up is minimal and the model can be incorporated into teaching curricula. Copyright © 2013 Elsevier Inc. All rights reserved.

APOL1 genetic variants are not associated with longitudinal blood pressure in young black adults.

PubMed

Chen, Teresa K; Estrella, Michelle M; Vittinghoff, Eric; Lin, Feng; Gutierrez, Orlando M; Kramer, Holly; Lewis, Cora E; Kopp, Jeffrey B; Allen, Norrina B; Winkler, Cheryl A; Bibbins-Domingo, Kirsten B; Peralta, Carmen A

2017-10-01

Whether APOL1 polymorphisms contribute to the excess risk of hypertension among blacks is unknown. To assess this we evaluated whether self-reported race and, in blacks, APOL1 risk variants (high-risk [2 risk alleles] versus low-risk [0-1 risk allele]) were associated with longitudinal blood pressure. Blood pressure trajectories were determined using linear mixed-effects (slope) and latent class models (5 distinct groups) during 25 years of follow-up in the Coronary Artery Risk Development in Young Adults Study. Associations of race and APOL1 genotypes with blood pressure change, separately, using linear mixed-effects and multinomial logistic regression models, adjusting for demographic, socioeconomic, and traditional hypertension risk factors, anti-hypertensive medication use, and kidney function were evaluated. Among 1700 whites and 1330 blacks (13% APOL1 high-risk, mean age 25 years; 46% male) mean mid-, ([systolic + diastolic blood pressure]/2), systolic, and diastolic blood pressures were 89, 110, and 69 mm Hg, respectively. One percent of participants used anti-hypertensive medications at baseline. Compared to whites, blacks, regardless of APOL1 genotype, had significantly greater increases in mid-blood pressure and were more likely to experience significantly increasing mid-blood pressure trajectories with adjusted relative risk ratios of 5.21 and 7.27 for moderate-increasing and elevated-increasing versus low-stable blood pressure, respectively. Among blacks, longitudinal mid-blood pressure changes and mid-blood pressure trajectory classification were similar by APOL1 risk status. Modeling systolic and diastolic blood pressure as outcomes yielded similar findings. From young adulthood to mid-life, blacks have greater blood pressure increases versus whites that are not fully explained by traditional risk factors. Thus APOL1 variants are not associated with longitudinal blood pressure in blacks. Copyright © 2017 International Society of Nephrology. All

Modelling science trustworthiness under publish or perish pressure

PubMed Central

Ioannidis, John P. A.

2018-01-01

Scientific publication is immensely important to the scientific endeavour. There is, however, concern that rewarding scientists chiefly on publication creates a perverse incentive, allowing careless and fraudulent conduct to thrive, compounded by the predisposition of top-tier journals towards novel, positive findings rather than investigations confirming null hypothesis. This potentially compounds a reproducibility crisis in several fields, and risks undermining science and public trust in scientific findings. To date, there has been comparatively little modelling on factors that influence science trustworthiness, despite the importance of quantifying the problem. We present a simple phenomenological model with cohorts of diligent, careless and unethical scientists, with funding allocated by published outputs. This analysis suggests that trustworthiness of published science in a given field is influenced by false positive rate, and pressures for positive results. We find decreasing available funding has negative consequences for resulting trustworthiness, and examine strategies to combat propagation of irreproducible science. PMID:29410855

Surrogate modeling of joint flood risk across coastal watersheds

NASA Astrophysics Data System (ADS)

Bass, Benjamin; Bedient, Philip

2018-03-01

This study discusses the development and performance of a rapid prediction system capable of representing the joint rainfall-runoff and storm surge flood response of tropical cyclones (TCs) for probabilistic risk analysis. Due to the computational demand required for accurately representing storm surge with the high-fidelity ADvanced CIRCulation (ADCIRC) hydrodynamic model and its coupling with additional numerical models to represent rainfall-runoff, a surrogate or statistical model was trained to represent the relationship between hurricane wind- and pressure-field characteristics and their peak joint flood response typically determined from physics based numerical models. This builds upon past studies that have only evaluated surrogate models for predicting peak surge, and provides the first system capable of probabilistically representing joint flood levels from TCs. The utility of this joint flood prediction system is then demonstrated by improving upon probabilistic TC flood risk products, which currently account for storm surge but do not take into account TC associated rainfall-runoff. Results demonstrate the source apportionment of rainfall-runoff versus storm surge and highlight that slight increases in flood risk levels may occur due to the interaction between rainfall-runoff and storm surge as compared to the Federal Emergency Management Association's (FEMAs) current practices.

Geomechanical modelling of induced seismicity using Coulomb stress and pore pressure changes

NASA Astrophysics Data System (ADS)

Zhao, B.; Shcherbakov, R.

2016-12-01

In recent years, there has been a dramatic increase in seismicity (earthquakes) due to anthropogenic activities related to the unconventional oil and gas exploration in the Western Canada Sedimentary Basin (WCSB). There are compelling evidences that hydraulic fracturing and wastewater injection operations play a key role in induced seismicity in the WCSB; however, their physical mechanisms are still not fully understood. Therefore, this study focuses on exploring the physical mechanisms of induced seismicity and developing a realistic geomechanical model by incorporating the past seismicity and well production data. In this work, we model the Coulomb stress changes due to past moderate (magnitude greater than 3 with known fault plane solutions) induced earthquakes and pore pressure changes due to wastewater injection in Alberta, specifically in Fox Creek and Fort St. John areas. Relationships between Coulombs stress changes, fault geometry and orientation and subsequent earthquake locations are tested. Subsurface flow due to injection well operations is studied to model the pore pressure changes in time and space, using known well production data, which include well types, well locations and water extraction and injection rates. By modelling the changes in pore pressure and Coulomb stress, we aim at constraining the time scale of occurrence of possible future earthquakes. The anticipating results can help to control the parameters of anthropogenic energy related operations such as hydraulic fracturing and wastewater injection in mitigating the risk due to induced seismicity.

Providing pressure inputs to multizone building models

DOE PAGES

Herring, Steven J.; Batchelor, Simon; Bieringer, Paul E.; ...

2016-02-13

A study to assess how the fidelity of wind pressure inputs and indoor model complexity affect the predicted air change rate for a study building is presented. The purpose of the work is to support the development of a combined indoor-outdoor hazard prediction tool, which links the CONTAM multizone building simulation tool with outdoor dispersion models. The study building, representing a large office block of a simple rectangular geometry under natural ventilation, was based on a real building used in the Joint Urban 2003 experiment. A total of 1600 indoor model flow simulations were made, driven by 100 meteorological conditionsmore » which provided a wide range of building surface pressures. These pressures were applied at four levels of resolution to four different building configurations with varying numbers of internal zones and indoor and outdoor flow paths. Analysis of the results suggests that surface pressures and flow paths across the envelope should be specified at a resolution consistent with the dimensions of the smallest volume of interest, to ensure that appropriate outputs are obtained.« less

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

A flamelet model for supersonic non-premixed combustion with pressure variation

NASA Astrophysics Data System (ADS)

Zhao, Guo-Yan; Sun, Ming-Bo; Wu, Jin-Shui; Wang, Hong-Bo

2015-08-01

A modified flamelet model is proposed for studying supersonic combustion with pressure variation considering that pressure is far from homogenous in a supersonic combustor. In this model, the flamelet database are tabulated at a reference pressure, while quantities at other pressure are obtained using a sixth-order polynomial in pressure. Attributed to merit of the modified model which compute coefficients for the expansion only. And they brought less requirements for memory and table lookup time, expensive cost is avoided. The performance of modified model is much better than the approach of using a flamelet model-based method with tabulation at different pressure values. Two types of hydrogen fueled scramjet combustors were introduced to validate the modified flamelet model. It was observed that the temperature is sensitive to the choice of model in combustion area, which in return will significantly affect the pressure. It was found that the results of modified model were in good agreement with the experimental data compared with the isobaric flamelet model, especially for temperature, whose value is more accurately predicted. It is concluded that the modified flamelet model was more effective for cases with a wide range of pressure variation.

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. © 2012 Society for Risk Analysis.

I am not "umqwayito'': a qualitative study of peer pressure and sexual risk behaviour among young adolescents in Cape Town, South Africa.

PubMed

Selikow, Terry-Ann; Ahmed, Nazeema; Flisher, Alan J; Mathews, Catherine; Mukoma, Wanjiru

2009-06-01

Young people in South Africa are susceptible to HIV infection. They are vulnerable to peer pressure to have sex, but little is known about how peer pressure operates. The aim of the study was to understand how negative peer pressure increases high risk sexual behaviour among young adolescents in Cape Town, South Africa. Qualitative research methods were used. Eight focus groups were conducted with young people between the ages of 13 and 14 years. Peer pressure among both boys and girls undermines healthy social norms and HIV prevention messages to abstain, be faithful, use a condom and delay sexual debut. HIV prevention projects need to engage with peer pressure with the aim of changing harmful social norms into healthy norms. Increased communication with adults about sex is one way to decrease the impact of negative peer pressure. Peer education is a further mechanism by which trained peers can role model healthy social norms and challenge a peer culture that promotes high risk sexual behaviour. Successful HIV prevention interventions need to engage with the disconnect between educational messages and social messages and to exploit the gaps between awareness, decision making, norms, intentions and actions as spaces for positive interventions.

[Study on relationship between prevalence or co-prevalence of risk factors for cardiovascular disease and blood pressure level in adults in China].

PubMed

Chen, Z H; Zhang, M; Li, Y C; Zhao, Z P; Zhang, X; Huang, Z J; Li, C; Wang, L M

2018-05-10

Objective: To study the relationship between blood pressure level and major risk factors for cardiovascular diseases in adults in China. Methods: A total of 179 347 adults aged ≥18 years were recruited from 298 surveillance points in 31 provinces in China in 2013 through complex multistage stratified sampling. The survey included face to face interview and physical examination to collect information about risk factors, such as smoking, drinking, diet pattern, physical activity, overweight or obesity, and the prevalence of hypertension. The blood pressure was classified into 6 levels (ideal blood pressure, normal blood pressure, normal high blood pressure and hypertension phase Ⅰ, Ⅱ and Ⅲ). The relationship between the prevalence or co-prevalence of risk factors for cardiovascular disease and blood pressure was analyzed. Results: The adults with ideal blood pressure, normal blood pressure, normal high pressure, hypertension phase Ⅰ, Ⅱ and Ⅲ accounted for 36.14 % , 22.77 % , 16.22 % , 16.43 % , 5.97 % and 2.48 % , respectively. Among them, the blood pressure was higher in men, people in Han ethnic group and those married, and the blood pressure was higher in those with older age, lower income level and lower education level, the differences were all significant ( P <0.05). Whether taking antihypertensive drug or not, co-prevalence of risk factors influenced the blood pressure levels of both sexes ( P <0.05), and the blood pressure levels of those taking no antihypertensive drug was influenced more by the co-prevalence of risk factors. Finally, multiple logistic analysis showed that the risks for high blood pressure in adults with 1, 2 and ≥3 risk factors were 1.36, 1.79 and 2.38 times higher, respectively, than that of the adults without risk factor. Conclusion: The more the risk factors for cardiovascular disease in adults, the higher their blood pressure were. It is necessary to conduct comprehensive behavior intervention targeting ≥ 2 risk

A whole-body mathematical model for intracranial pressure dynamics.

PubMed

Lakin, William D; Stevens, Scott A; Tranmer, Bruce I; Penar, Paul L

2003-04-01

Most attempts to study intracranial pressure using lumped-parameter models have adopted the classical "Kellie-Monro Doctrine," which considers the intracranial space to be a closed system that is confined within the nearly-rigid skull, conserves mass, and has equal inflow and outflow. The present work revokes this Doctrine and develops a mathematical model for the dynamics of intracranial pressures, volumes, and flows that embeds the intracranial system in extensive whole-body physiology. The new model consistently introduces compartments representing the tissues and vasculature of the extradural portions of the body, including both the thoracic region and the lower extremities. In addition to vascular connections, a spinal-subarachnoid cerebrospinal fluid (CSF) compartment bridges intracranial and extracranial physiology allowing explict buffering of intracranial pressure fluctuations by the spinal theca. The model contains cerebrovascular autoregulation, regulation of systemic vascular pressures by the sympathetic nervous system, regulation of CSF production in the choroid plexus, a lymphatic system, colloid osmotic pressure effects, and realistic descriptions of cardiac output. To validate the model in situations involving normal physiology, the model's response to a realistic pulsatile cardiac output is examined. A well-known experimentally-derived intracranial pressure-volume relationship is recovered by using the model to simulate CSF infusion tests, and the effect on cerebral blood flow of a change in body position is also examined. Cardiac arrest and hemorrhagic shock are simulated to demonstrate the predictive capabilities of the model in pathological conditions.

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. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

Prophylactic negative-pressure wound therapy after cesarean is associated with reduced risk of surgical site infection: a systematic review and meta-analysis.

PubMed

Yu, Lulu; Kronen, Ryan J; Simon, Laura E; Stoll, Carolyn R T; Colditz, Graham A; Tuuli, Methodius G

2018-02-01

The objective of the study was to assess the effect of prophylactic negative-pressure wound therapy on surgical site infections and other wound complications in women after cesarean delivery. We searched Ovid Medline, Embase, SCOPUS, Cochrane Database of Systematic Reviews, and ClinicalTrials.gov. We included randomized controlled trials and observational studies comparing prophylactic negative-pressure wound therapy with standard wound dressing for cesarean delivery. The primary outcome was surgical site infection after cesarean delivery. Secondary outcomes were composite wound complications, wound dehiscence, wound seroma, endometritis, and hospital readmission. Heterogeneity was assessed using Higgin's I 2 . Relative risks with 95% confidence intervals were calculated using random-effects models. Six randomized controlled trials and 3 cohort studies in high-risk mostly obese women met inclusion criteria and were included in the meta-analysis. Six were full-text articles, 2 published abstracts, and 1 report of trial results in ClinicalTrials.gov. Studies were also heterogeneous in the patients included and type of negative-pressure wound therapy device. The risk of surgical site infection was significantly lower with the use of prophylactic negative-pressure wound therapy compared with standard wound dressing (7 studies: pooled risk ratio, 0.45; 95% confidence interval, 0.31-0.66; adjusted risk ratio, -6.0%, 95% confidence interval, -10.0% to -3.0%; number needed to treat, 17, 95% confidence interval, 10-34). There was no evidence of significant statistical heterogeneity (I 2  = 9.9%) or publication bias (Egger P = .532). Of the secondary outcomes, only composite wound complications were significantly reduced in patients receiving prophylactic negative-pressure wound therapy compared with standard dressing (9 studies: pooled risk ratio, 0.68, 95% confidence interval, 0.49-0.94). Studies on the effectiveness of prophylactic negative-pressure wound therapy at

As of 2012, what are the key predictive risk factors for pressure ulcers? Developing French guidelines for clinical practice.

PubMed

Michel, J-M; Willebois, S; Ribinik, P; Barrois, B; Colin, D; Passadori, Y

2012-10-01

An evaluation of predictive risk factors for pressure ulcers is essential in development of a preventive strategy on admission to hospitals and/or nursing homes. Identification of the predictive factors for pressure ulcers as of 2012. Systematic review of the literature querying the databases PASCAL Biomed, Cochrane Library and PubMed from 2000 through 2010. Immobility should be considered as a predictive risk factor for pressure ulcers (grade B). Undernutrition/malnutrition may also be a predictive risk factor for pressure ulcers (grade C). Even if the level of evidence is low, once these risk factors have been detected, management is essential. Sensitizing and mobilizing health care teams requires training in ways of tracking and screening. According to the experts, risk scales should be used. As decision aids, they should always be balanced and complemented by the clinical judgment of the treatment team. According to experts, it is important to know and predictively evaluate risk of pressure ulcers at the time of hospital admission. The predictive risk factors found in this study are identical to those highlighted at the 2001 consensus conference of which was PERSE was the promoter. Copyright © 2012. Published by Elsevier Masson SAS.

Models of brachial to finger pulse wave distortion and pressure decrement.

PubMed

Gizdulich, P; Prentza, A; Wesseling, K H

1997-03-01

To model the pulse wave distortion and pressure decrement occurring between brachial and finger arteries. Distortion reversion and decrement correction were also our aims. Brachial artery pressure was recorded intra-arterially and finger pressure was recorded non-invasively by the Finapres technique in 53 adult human subjects. Mean pressure was subtracted from each pressure waveform and Fourier analysis applied to the pulsations. A distortion model was estimated for each subject and averaged over the group. The average inverse model was applied to the full finger pressure waveform. The pressure decrement was modelled by multiple regression on finger systolic and diastolic levels. Waveform distortion could be described by a general, frequency dependent model having a resonance at 7.3 Hz. The general inverse model has an anti-resonance at this frequency. It converts finger to brachial pulsations thereby reducing average waveform distortion from 9.7 (s.d. 3.2) mmHg per sample for the finger pulse to 3.7 (1.7) mmHg for the converted pulse. Systolic and diastolic level differences between finger and brachial arterial pressures changed from -4 (15) and -8 (11) to +8 (14) and +8 (12) mmHg, respectively, after inverse modelling, with pulse pressures correct on average. The pressure decrement model reduced both the mean and the standard deviation of systolic and diastolic level differences to 0 (13) and 0 (8) mmHg. Diastolic differences were thus reduced most. Brachial to finger pulse wave distortion due to wave reflection in arteries is almost identical in all subjects and can be modelled by a single resonance. The pressure decrement due to flow in arteries is greatest for high pulse pressures superimposed on low means.

Acute-Phase Blood Pressure Levels Correlate With a High Risk of Recurrent Strokes in Young-Onset Ischemic Stroke.

PubMed

Mustanoja, Satu; Putaala, Jukka; Gordin, Daniel; Tulkki, Lauri; Aarnio, Karoliina; Pirinen, Jani; Surakka, Ida; Sinisalo, Juha; Lehto, Mika; Tatlisumak, Turgut

2016-06-01

High blood pressure (BP) in acute stroke has been associated with a poor outcome; however, this has not been evaluated in young adults. The relationship between BP and long-term outcome was assessed in 1004 consecutive young, first-ever ischemic stroke patients aged 15 to 49 years enrolled in the Helsinki Young Stroke Registry. BP parameters included systolic (SBP) and diastolic BP, pulse pressure, and mean arterial pressure at admission and 24 hours. The primary outcome measure was recurrent stroke in the long-term follow-up. Adjusted for demographics and preexisting comorbidities, Cox regression models were used to assess independent BP parameters associated with outcome. Of our patients (63% male), 393 patients (39%) had prestroke hypertension and 358 (36%) used antihypertensive treatment. The median follow-up period was 8.9 years (interquartile range 5.7-13.2). Patients with a recurrent stroke (n=142, 14%) had significantly higher admission SBP, diastolic BP, pulse pressure, and mean arterial pressure (P<0.001) and 24-h SBP, diastolic BP, and mean arterial pressure compared with patients without the recurrent stroke. Patients with SBP ≥160 mm Hg compared with those with SBP <160 mm Hg had significantly more recurrent strokes (hazard ratio 3.3 [95% confidence interval, 2.05-4.55]; P<0.001) occurring earlier (13.9 years [13.0-14.6] versus 16.2 [15.8-16.6]; P<0.001) within the follow-up period. In multivariable analyses, higher admission SBP, diastolic BP, pulse pressure, and mean arterial pressure were independently associated with the risk of recurrent stroke, while the 24-hour BP levels were not. In young ischemic stroke patients, high acute phase BP levels are independently associated with a high risk of recurrent strokes. © 2016 American Heart Association, Inc.

Pressure prediction model for compression garment design.

PubMed

Leung, W Y; Yuen, D W; Ng, Sun Pui; Shi, S Q

2010-01-01

Based on the application of Laplace's law to compression garments, an equation for predicting garment pressure, incorporating the body circumference, the cross-sectional area of fabric, applied strain (as a function of reduction factor), and its corresponding Young's modulus, is developed. Design procedures are presented to predict garment pressure using the aforementioned parameters for clinical applications. Compression garments have been widely used in treating burning scars. Fabricating a compression garment with a required pressure is important in the healing process. A systematic and scientific design method can enable the occupational therapist and compression garments' manufacturer to custom-make a compression garment with a specific pressure. The objectives of this study are 1) to develop a pressure prediction model incorporating different design factors to estimate the pressure exerted by the compression garments before fabrication; and 2) to propose more design procedures in clinical applications. Three kinds of fabrics cut at different bias angles were tested under uniaxial tension, as were samples made in a double-layered structure. Sets of nonlinear force-extension data were obtained for calculating the predicted pressure. Using the value at 0° bias angle as reference, the Young's modulus can vary by as much as 29% for fabric type P11117, 43% for fabric type PN2170, and even 360% for fabric type AP85120 at a reduction factor of 20%. When comparing the predicted pressure calculated from the single-layered and double-layered fabrics, the double-layered construction provides a larger range of target pressure at a particular strain. The anisotropic and nonlinear behaviors of the fabrics have thus been determined. Compression garments can be methodically designed by the proposed analytical pressure prediction model.

Recent development of risk-prediction models for incident hypertension: An updated systematic review

PubMed Central

Xiao, Lei; Liu, Ya; Wang, Zuoguang; Li, Chuang; Jin, Yongxin; Zhao, Qiong

2017-01-01

Background Hypertension is a leading global health threat and a major cardiovascular disease. Since clinical interventions are effective in delaying the disease progression from prehypertension to hypertension, diagnostic prediction models to identify patient populations at high risk for hypertension are imperative. Methods Both PubMed and Embase databases were searched for eligible reports of either prediction models or risk scores of hypertension. The study data were collected, including risk factors, statistic methods, characteristics of study design and participants, performance measurement, etc. Results From the searched literature, 26 studies reporting 48 prediction models were selected. Among them, 20 reports studied the established models using traditional risk factors, such as body mass index (BMI), age, smoking, blood pressure (BP) level, parental history of hypertension, and biochemical factors, whereas 6 reports used genetic risk score (GRS) as the prediction factor. AUC ranged from 0.64 to 0.97, and C-statistic ranged from 60% to 90%. Conclusions The traditional models are still the predominant risk prediction models for hypertension, but recently, more models have begun to incorporate genetic factors as part of their model predictors. However, these genetic predictors need to be well selected. The current reported models have acceptable to good discrimination and calibration ability, but whether the models can be applied in clinical practice still needs more validation and adjustment. PMID:29084293

Supplementing the Braden scale for pressure ulcer risk among medical inpatients: the contribution of self-reported symptoms and standard laboratory tests.

PubMed

Skogestad, Ingrid Johansen; Martinsen, Liv; Børsting, Tove Elisabet; Granheim, Tove Irene; Ludvigsen, Eirin Sigurdssøn; Gay, Caryl L; Lerdal, Anners

2017-01-01

To evaluate medical inpatients' symptom experience and selected laboratory blood results as indicators of their pressure ulcer risk as measured by the Braden scale. Pressure ulcers reduce quality of life and increase treatment costs. The prevalence of pressure ulcers is 6-23% in hospital populations, but literature suggests that most pressure ulcers are avoidable. Prospective, cross-sectional survey. Three hundred and twenty-eight patients admitted to medical wards in an acute hospital in Oslo, Norway consented to participate. Data were collected on 10 days between 2012-2014 by registered nurses and nursing students. Pressure ulcer risk was assessed using the Braden scale, and scores <19 indicated pressure ulcer risk. Skin examinations were categorised as normal or stages I-IV using established definitions. Comorbidities were collected by self-report. Self-reported symptom occurrence and distress were measured with 15 items from the Memorial Symptom Assessment Scale, and pain was assessed using two numeric rating scales. Admission laboratory data were collected from medical records. Prevalence of pressure ulcers was 11·9, and 20·4% of patients were identified as being at risk for developing pressure ulcers. Multivariable analysis showed that pressure ulcer risk was positively associated with age ≥80 years, vomiting, severe pain at rest, urination problems, shortness of breath and low albumin and was negatively associated with nervousness. Our study indicates that using patient-reported symptoms and standard laboratory results as supplemental indicators of pressure ulcer risk may improve identification of vulnerable patients, but replication of these findings in other study samples is needed. Nurses play a key role in preventing pressure ulcers during hospitalisation. A better understanding of the underlying mechanisms may improve the quality of care. Knowledge about symptoms associated with pressure ulcer risk may contribute to a faster clinical judgment of

Low pressure versus standard pressure pneumoperitoneum in laparoscopic cholecystectomy.

PubMed

Gurusamy, Kurinchi Selvan; Vaughan, Jessica; Davidson, Brian R

2014-03-18

A pneumoperitoneum of 12 to 16 mm Hg is used for laparoscopic cholecystectomy. Lower pressures are claimed to be safe and effective in decreasing cardiopulmonary complications and pain. To assess the benefits and harms of low pressure pneumoperitoneum compared with standard pressure pneumoperitoneum in people undergoing laparoscopic cholecystectomy. We searched the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library, MEDLINE, EMBASE, and Science Citation Index Expanded until February 2013 to identify randomised trials,using search strategies. We considered only randomised clinical trials, irrespective of language, blinding, or publication status for inclusion in the review. Two review authors independently identified trials and independently extracted data. We calculated the risk ratio (RR), mean difference (MD), or standardised mean difference (SMD) with 95% confidence intervals (CI) using both fixed-effect and random-effects models with RevMan 5 based on available case analysis. A total of 1092 participants randomly assigned to the low pressure group (509 participants) and the standard pressure group (583 participants) in 21 trials provided information for this review on one or more outcomes. Three additional trials comparing low pressure pneumoperitoneum with standard pressure pneumoperitoneum (including 179 participants) provided no information for this review. Most of the trials included low anaesthetic risk participants undergoing elective laparoscopic cholecystectomy. One trial including 140 participants was at low risk of bias. The remaining 20 trials were at high risk of bias. The overall quality of evidence was low or very low. No mortality was reported in either the low pressure group (0/199; 0%) or the standard pressure group (0/235; 0%) in eight trials that reported mortality. One participant experienced the outcome of serious adverse events (low pressure group 1/179, 0.6%; standard pressure group 0/215, 0%; seven trials

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.

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.

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.

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

Evaluation of the Validity and Reliability of the Waterlow Pressure Ulcer Risk Assessment Scale

PubMed Central

Charalambous, Charalambos; Koulori, Agoritsa; Vasilopoulos, Aristidis; Roupa, Zoe

2018-01-01

Introduction Prevention is the ideal strategy to tackle the problem of pressure ulcers. Pressure ulcer risk assessment scales are one of the most pivotal measures applied to tackle the problem, much criticisms has been developed regarding the validity and reliability of these scales. Objective To investigate the validity and reliability of the Waterlow pressure ulcer risk assessment scale. Method The methodology used is a narrative literature review, the bibliography was reviewed through Cinahl, Pubmed, EBSCO, Medline and Google scholar, 26 scientific articles where identified. The articles where chosen due to their direct correlation with the objective under study and their scientific relevance. Results The construct and face validity of the Waterlow appears adequate, but with regards to content validity changes in the category age and gender can be beneficial. The concurrent validity cannot be assessed. The predictive validity of the Waterlow is characterized by high specificity and low sensitivity. The inter-rater reliability has been demonstrated to be inadequate, this may be due to lack of clear definitions within the categories and differentiating level of knowledge between the users. Conclusion Due to the limitations presented regarding the validity and reliability of the Waterlow pressure ulcer risk assessment scale, the scale should be used in conjunction with clinical assessment to provide optimum results. PMID:29736104

Evaluation of the Validity and Reliability of the Waterlow Pressure Ulcer Risk Assessment Scale.

PubMed

Charalambous, Charalambos; Koulori, Agoritsa; Vasilopoulos, Aristidis; Roupa, Zoe

2018-04-01

Prevention is the ideal strategy to tackle the problem of pressure ulcers. Pressure ulcer risk assessment scales are one of the most pivotal measures applied to tackle the problem, much criticisms has been developed regarding the validity and reliability of these scales. To investigate the validity and reliability of the Waterlow pressure ulcer risk assessment scale. The methodology used is a narrative literature review, the bibliography was reviewed through Cinahl, Pubmed, EBSCO, Medline and Google scholar, 26 scientific articles where identified. The articles where chosen due to their direct correlation with the objective under study and their scientific relevance. The construct and face validity of the Waterlow appears adequate, but with regards to content validity changes in the category age and gender can be beneficial. The concurrent validity cannot be assessed. The predictive validity of the Waterlow is characterized by high specificity and low sensitivity. The inter-rater reliability has been demonstrated to be inadequate, this may be due to lack of clear definitions within the categories and differentiating level of knowledge between the users. Due to the limitations presented regarding the validity and reliability of the Waterlow pressure ulcer risk assessment scale, the scale should be used in conjunction with clinical assessment to provide optimum results.

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.

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.

Pressure And Thermal Modeling Of Rocket Launches

NASA Technical Reports Server (NTRS)

Smith, Sheldon D.; Myruski, Brian L.; Farmer, Richard C.; Freeman, Jon A.

1995-01-01

Report presents mathematical model for use in designing rocket-launching stand. Predicts pressure and thermal environment, as well as thermal responses of structures to impinging rocket-exhaust plumes. Enables relatively inexperienced analyst to determine time-varying distributions and absolute levels of pressure and heat loads on structures.

Breast cancer risks and risk prediction models.

PubMed

Engel, Christoph; Fischer, Christine

2015-02-01

BRCA1/2 mutation carriers have a considerably increased risk to develop breast and ovarian cancer. The personalized clinical management of carriers and other at-risk individuals depends on precise knowledge of the cancer risks. In this report, we give an overview of the present literature on empirical cancer risks, and we describe risk prediction models that are currently used for individual risk assessment in clinical practice. Cancer risks show large variability between studies. Breast cancer risks are at 40-87% for BRCA1 mutation carriers and 18-88% for BRCA2 mutation carriers. For ovarian cancer, the risk estimates are in the range of 22-65% for BRCA1 and 10-35% for BRCA2. The contralateral breast cancer risk is high (10-year risk after first cancer 27% for BRCA1 and 19% for BRCA2). Risk prediction models have been proposed to provide more individualized risk prediction, using additional knowledge on family history, mode of inheritance of major genes, and other genetic and non-genetic risk factors. User-friendly software tools have been developed that serve as basis for decision-making in family counseling units. In conclusion, further assessment of cancer risks and model validation is needed, ideally based on prospective cohort studies. To obtain such data, clinical management of carriers and other at-risk individuals should always be accompanied by standardized scientific documentation.

Future cardiovascular disease in China: Markov model and risk factor scenario projections from the Coronary Heart Disease Policy Model-China

PubMed Central

Moran, Andrew; Gu, Dongfeng; Zhao, Dong; Coxson, Pamela; Wang, Y. Claire; Chen, Chung-Shiuan; Liu, Jing; Cheng, Jun; Bibbins-Domingo, Kirsten; Shen, Yu-Ming; He, Jiang; Goldman, Lee

2010-01-01

Background The relative effects of individual and combined risk factor trends on future cardiovascular disease in China have not been quantified in detail. Methods and Results Future risk factor trends in China were projected based on prior trends. Cardiovascular disease (coronary heart disease and stroke) in adults ages 35 to 84 years was projected from 2010 to 2030 using the Coronary Heart Disease Policy Model–China, a Markov computer simulation model. With risk factor levels held constant, projected annual cardiovascular events increased by >50% between 2010 and 2030 based on population aging and growth alone. Projected trends in blood pressure, total cholesterol, diabetes (increases), and active smoking (decline) would increase annual cardiovascular disease events by an additional 23%, an increase of approximately 21.3 million cardiovascular events and 7.7 million cardiovascular deaths over 2010 to 2030. Aggressively reducing active smoking in Chinese men to 20% prevalence in 2020 and 10% prevalence in 2030 or reducing mean systolic blood pressure by 3.8 mm Hg in men and women would counteract adverse trends in other risk factors by preventing cardiovascular events and 2.9 to 5.7 million total deaths over 2 decades. Conclusions Aging and population growth will increase cardiovascular disease by more than a half over the coming 20 years, and projected unfavorable trends in blood pressure, total cholesterol, diabetes, and body mass index may accelerate the epidemic. National policy aimed at controlling blood pressure, smoking, and other risk factors would counteract the expected future cardiovascular disease epidemic in China. PMID:20442213

Assessing the Impact of Agricultural Pressures on N and P Loads and Potential Eutrophication Risk at Regional Scales

NASA Astrophysics Data System (ADS)

Dupas, R.; Gascuel-odoux, C.; Delmas, M.; Moatar, F.

2014-12-01

Excessive nutrient loading of freshwater bodies results in increased eutrophication risk worldwide. The processes controlling N/P transfer in agricultural landscapes are well documented through scientific studies conducted in intensively monitored catchments. However, managers need tools to assess water quality and evaluate the contribution of agriculture to eutrophication at regional scales, including unmonitored or poorly monitored areas. To this end, we present an assessment framework which includes: i) a mass-balance model to estimate diffuse N/P transfer and retention and ii) indicators based on N:P:Si molar ratios to assess potential eutrophication risk from external loads. The model, called Nutting (Dupas et al., 2013), integrates variables for both detailed description of agricultural pressures (N surplus, soil P content) and characterisation of physical attributes of catchments (including spatial attributes). It was calibrated on 160 catchments, and applied to 2210 unmonitored headwater bodies in France (Dupas et al., under review). N and P retention represented 53% and 95% of soil N and P surplus, respectively, and was mainly controlled by runoff and an index characterising infiltration/runoff properties. According to our estimates, diffuse agricultural sources represented a mean of 97% of N loads and N exceeded Si in 93% of the catchments, whilst they represented 46% of P loads and P exceeded Si in 26-65% of the catchments. Estimated eutrophication risk was highly sensitive to assumptions about P bioavailability, hence the range of headwaters potentially at risk spanned 26-63% of the catchments, depending on assumptions. To reduce this uncertainty, we recommend introducing P bioavailability tests in water monitoring programs, especially in sensitive areas. Dupas R et al. Assessing N emissions in surface water at the national level: comparison of country-wide vs. regionalized models. Sci Total Environ 2013; 443: 152-62. Dupas R et al. Assessing the impact

Systolic blood pressure, arterial rigidity, and risk of stroke. The Framingham study.

PubMed

Kannel, W B; Wolf, P A; McGee, D L; Dawber, T R; McNamara, P; Castelli, W P

1981-03-27

Based on prospective data from the Framingham study relating systolic pressure, diastolic pressure, age, and pulse-wave configuration to future stroke incidence, it would appear that isolated systolic hypertension predisposes to stroke independent of arterial rigidity. The prevalence of isolated systolic hypertension increased with age and with the degree of blunting of the dicrotic notch in the pulse wave. Subjects with isolated systolic hypertension experienced two to four times as many strokes as did normotensive persons. While diastolic pressure is related to stroke incidence, in the subject with systolic hypertension, the diastolic component adds little to risk assessment and in men, in this subgroup, appears unrelated to stroke incidence.

Comparing visual and objective skin assessment with pressure injury risk.

PubMed

Borzdynski, Caroline J; McGuiness, William; Miller, Charne

2016-08-01

Contemporary approaches to pressure injury (PI) risk identification rely on the use of risk assessment tools and visual skin assessment. Objective biophysical measures that assess skin hydration, melanin, erythema and lipids have not been traditionally used in PI risk; however, these may prove useful as a risk assessment tool. The relationship between subjective visual assessments of skin condition, biophysical measures and PI risk warrants investigation. This study used a descriptive correlational design to examine the relationship between measures of skin hydration, colour (melanin and erythema) and lipids at PI-prone areas amongst geriatric persons (n = 38), obtained using biophysical skin measures and visual skin assessment. Twice daily measures of epidermal hydration, colour and lipids were assessed using the SD202 Skin Diagnostic (Courage + Khazaka GmBH, Cologne, Germany) over pressure-prone areas of the body of study participants over seven consecutive days. Concurrent visual assessment of skin hydration and colour was performed. Results obtained using the SD202 Skin Diagnostic were compared with results gathered from visual assessment and examined for their association with participants' PI risk based on scores of the Norton Risk Assessment Scale. While epidermal hydration and skin colour reading scores did not vary significantly over the data collection period, lipid readings could not be registered on any occasion. With the exception of skin dryness, skin parameters via both objective and subjective means had significant, positive correlations. Statistically significant correlations emerged between visual assessment of skin wetness at the sacrum (r = -0·441, P < 0·01) and ischia (r = -0·468, P < 0·01) and Norton Risk Assessment Scale scores. It was found that the objective assessment of epidermal hydration (skin wetness) was also significantly associated with PI risk at the sacrum (r = -0·528, P < 0·01), as well as the right ischia (r = -0·410, P

Integrating eating disorder-specific risk factors into the acquired preparedness model of dysregulated eating: A moderated mediation analysis.

PubMed

Racine, Sarah E; Martin, Shelby J

2017-01-01

Tests of the acquired preparedness model demonstrate that the personality trait of negative urgency (i.e., the tendency to act impulsively when distressed) predicts the expectation that eating alleviates negative affect, and this eating expectancy subsequently predicts dysregulated eating. Although recent data indicate that eating disorder-specific risk factors (i.e., appearance pressures, thin-ideal internalization, body dissatisfaction, dietary restraint) strengthen negative urgency-dysregulated eating associations, it is unclear whether these risk factors impact associations directly or indirectly (i.e., through eating expectancies). The current study used latent moderated structural equation modeling to test moderated mediation hypotheses in a sample of 313 female college students. Eating expectancies mediated the association between negative urgency and dysregulated eating, and the indirect effect of negative urgency on dysregulated eating through eating expectancies was conditional on level of each eating disorder risk factor. Appearance pressures, thin-ideal internalization, body dissatisfaction, and dietary restraint significantly moderated the association between eating expectancies and dysregulated eating, while only dietary restraint moderated the direct effect of negative urgency on dysregulated eating. Findings suggest that the development of high-risk eating expectancies among individuals with negative urgency, combined with sociocultural pressures for thinness and their consequences, is associated with the greatest risk for dysregulated eating. Copyright © 2016 Elsevier Ltd. All rights reserved.

Nutrition care-related practices and factors affecting nutritional intakes in hospital patients at risk of pressure ulcers.

PubMed

Roberts, S; Chaboyer, W; Desbrow, B

2015-08-01

Malnutrition is common in hospitals and is a risk factor for pressure ulcers. Nutrition care practices relating to the identification and treatment of malnutrition have not been assessed in patients at risk of pressure ulcers. The present study describes nutrition care practices and factors affecting nutritional intakes in this patient group. The study was conducted in four wards at two hospitals in Queensland, Australia. Adult patients at risk of pressure ulcers as a result of restricted mobility were observed for 24 h to determine their daily oral intake and practices such as nutrition screening, documentation and intervention. Independent samples t-tests and chi-squared tests were used to analyse dietary intake and nutrition care-related data. Predictors of receiving a dietitian referral were identified using logistic regression analyses. Two hundred and forty-one patients participated in the present study. The observed nutritional screening rate was 59% (142 patients). Weight and height were documented in 71% and 34% of cases. Sixty-nine patients (29%) received a dietitian referral. Predictors of receiving a dietitian referral included lower body mass index and longer length of stay. On average, patients consumed 73% and 72% of the energy and protein provided, respectively. Between 22% and 38% of patients consumed <50% of food provided at main meals. Nutrition care practices including malnutrition risk screening and documentation of nutritional parameters appear to be inadequate in patients at risk of pressure ulcers. A significant proportion of these patients eat inadequately at main meals, further increasing their risk of malnutrition and pressure ulcers. © 2014 The British Dietetic Association Ltd.

A pilot study comparing custom contoured and planar support surfaces for pressure ulcer risk over the heels for night time postural management using interface pressure mapping and discomfort scores.

PubMed

Hosking, J

2017-08-01

Custom contouring techniques are effective for reducing pressure ulcer risk in wheelchair seating. These techniques may assist the management of pressure ulcer risk during sleep for night time postural management. To investigate the effectiveness of custom contoured night time postural management components against planar support surfaces for pressure ulcer risk measures over the heels. Supine posture was captured from five healthy participants using vacuum consolidation and 3-dimensional laser scanning. Custom contoured abduction wedges were carved from polyurethane and chipped foams. Pressure mapping and the visual analog scale were used to evaluate the effectiveness of the contoured foams in reducing pressure and discomfort under the posterior heel against standard planar support surfaces. Custom contoured shapes significantly reduced interface pressures (p < 0.05) and discomfort scores (p < 0.05) when compared to planar support surfaces. Polyurethane foam was the most effective material but it did not differ significantly from chipped foam. Linear regression revealed a significant relationship between the Peak Pressure Index and discomfort scores (r = 0.997, p = 0.003). The findings of this pilot study suggested that custom contoured shapes were more effective than planar surfaces at reducing pressure ulcer risk surrogate measures over the posterior heels with polyurethane foam being the most effective material investigated. It is recommended that Evazote foam should not be used as a support surface material for night time postural management. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

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.…

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.

Morning and Evening Home Blood Pressure and Risks of Incident Stroke and Coronary Artery Disease in the Japanese General Practice Population: The Japan Morning Surge-Home Blood Pressure Study.

PubMed

Hoshide, Satoshi; Yano, Yuichiro; Haimoto, Hajime; Yamagiwa, Kayo; Uchiba, Kiyoshi; Nagasaka, Shoichiro; Matsui, Yoshio; Nakamura, Akira; Fukutomi, Motoki; Eguchi, Kazuo; Ishikawa, Joji; Kario, Kazuomi

2016-07-01

Our aim is to determine the optimal time schedule for home blood pressure (BP) monitoring that best predicts stroke and coronary artery disease in general practice. The Japan Morning Surge-Home Blood Pressure (J-HOP) study is a nationwide practice-based study that included 4310 Japanese with a history of or risk factors for cardiovascular disease, or both (mean age, 65 years; 79% used antihypertensive medication). Home BP measures were taken twice daily (morning and evening) over 14 days at baseline. During a mean follow-up of 4 years (16 929 person-years), 74 stroke and 77 coronary artery disease events occurred. Morning systolic BP (SBP) improved the discrimination of incident stroke (C statistics, 0.802; 95% confidence interval, 0.692-0.911) beyond traditional risk factors including office SBP (0.756; 0.646-0.866), whereas the changes were smaller with evening SBP (0.764; 0.653-0.874). The addition of evening SBP to the model (including traditional risk factors plus morning SBP) significantly reduced the discrimination of incident stroke (C statistics difference, -0.008; 95% confidence interval: -0.015 to -0.008; P=0.03). The category-free net reclassification improvement (0.3606; 95% confidence interval, 0.1317-0.5896), absolute integrated discrimination improvement (0.015; SE, 0.005), and relative integrated discrimination improvement (58.3%; all P<0.01) with the addition of morning SBP to the model (including traditional risk factors) were greater than those with evening SBP and with combined morning and evening SBP. Neither morning nor evening SBP improved coronary artery disease risk prediction. Morning home SBP itself should be evaluated to ensure best stroke prediction in clinical practice, at least in Japan. This should be confirmed in the different ethnic groups. URL: http://www.umin.ac.jp/ctr/. Unique identifier: UMIN000000894. © 2016 American Heart Association, Inc.

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.

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.

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.

Taste phenotype associates with cardiovascular disease risk factors via diet quality in multivariate modeling.

PubMed

Sharafi, Mastaneh; Rawal, Shristi; Fernandez, Maria Luz; Huedo-Medina, Tania B; Duffy, Valerie B

2018-05-08

Sensations from foods and beverages drive dietary choices, which in turn, affect risk of diet-related diseases. Perception of these sensation varies with environmental and genetic influences. This observational study aimed to examine associations between chemosensory phenotype, diet and cardiovascular disease (CVD) risk. Reportedly healthy women (n = 110, average age 45 ± 9 years) participated in laboratory-based measures of chemosensory phenotype (taste and smell function, propylthiouracil (PROP) bitterness) and CVD risk factors (waist circumference, blood pressure, serum lipids). Diet variables included preference and intake of sweet/high-fat foods, dietary restraint, and diet quality based on reported preference (Healthy Eating Preference Index-HEPI) and intake (Healthy Eating Index-HEI). We found that females who reported high preference yet low consumption of sweet/high-fat foods had the highest dietary restraint and depressed quinine taste function. PROP nontasters were more likely to report lower diet quality; PROP supertasters more likely to consume but not like a healthy diet. Multivariate structural models were fitted to identify predictors of CVD risk factors. Reliable latent taste (quinine taste function, PROP tasting) and smell (odor intensity) variables were identified, with taste explaining more variance in the CVD risk factors. Lower bitter taste perception was associated with elevated risk. In multivariate models, the HEPI completely mediated the taste-adiposity and taste-HDL associations and partially mediated the taste-triglyceride or taste-systolic blood pressure associations. The taste-LDL pathway was significant and direct. The HEI could not replace HEPI in adequate models. However, using a latent diet quality variable with HEPI and HEI, increased the strength of association between diet quality and adiposity or CVD risk factors. In conclusion, bitter taste phenotype was associated with CVD risk factors via diet quality

Cost-effectiveness Analysis of Nutritional Support for the Prevention of Pressure Ulcers in High-Risk Hospitalized Patients.

PubMed

Tuffaha, Haitham W; Roberts, Shelley; Chaboyer, Wendy; Gordon, Louisa G; Scuffham, Paul A

2016-06-01

To evaluate the cost-effectiveness of nutritional support compared with standard care in preventing pressure ulcers (PrUs) in high-risk hospitalized patients. An economic model using data from a systematic literature review. A meta-analysis of randomized controlled trials on the efficacy of nutritional support in reducing the incidence of PrUs was conducted. Modeled cohort of hospitalized patients at high risk of developing PrUs and malnutrition simulated during their hospital stay and up to 1 year. Standard care included PrU prevention strategies, such as redistribution surfaces, repositioning, and skin protection strategies, along with standard hospital diet. In addition to the standard care, the intervention group received nutritional support comprising patient education, nutrition goal setting, and the consumption of high-protein supplements. The analysis was from a healthcare payer perspective. Key outcomes of the model included the average costs and quality-adjusted life years. Model results were tested in univariate sensitivity analyses, and decision uncertainty was characterized using a probabilistic sensitivity analysis. Compared with standard care, nutritional support was cost saving at AU $425 per patient and marginally more effective with an average 0.005 quality-adjusted life years gained. The probability of nutritional support being cost-effective was 87%. Nutritional support to prevent PrUs in high-risk hospitalized patients is cost-effective with substantial cost savings predicted. Hospitals should implement the recommendations from the current PrU practice guidelines and offer nutritional support to high-risk patients.

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.

Adolescent blood pressure and blood pressure tracking into young adulthood are related to subclinical atherosclerosis: the Atherosclerosis Risk in Young Adults (ARYA) study.

PubMed

Vos, Lydia E; Oren, Anath; Uiterwaal, Cuno; Gorissen, Wim H M; Grobbee, Diederick E; Bots, Michiel L

2003-07-01

Increased blood pressure (BP) in young adulthood is associated with cardiovascular morbidity and mortality. Longitudinal studies of patients at young ages are, however, limited. Our aim was to study the relationships of adolescent BP and tracking of BP into young adulthood with subclinical atherosclerosis, as assessed by carotid intima-media thickness (CIMT), at the age of 28 years. The Atherosclerosis Risk in Young Adults (ARYA) study comprises of a community-based sample of 750 subjects aged 27 to 30 years. In the 352 men and 398 women, at least one BP measurement was recorded at a mean age of 13 years in school health records. Recently, all participants completed a questionnaire on cardiovascular risk factors, had a fasting blood sample drawn, and underwent an ultrasound examination of both common carotid arteries to assess CIMT. Linear regression showed that adolescent systolic BP was associated with thickening of the intima-media (an increase of 7.5 microm in CIMT per standard deviation increase in systolic BP; 95% CI 4.3 to 10.6). Similar relations were found for pulse pressure and mean arterial pressure. When sex, age, and body mass index at adolescence and young adulthood and adult BP were taken into account, the relations attenuated, but for pulse pressure they remained statistically significant. Furthermore, subjects who tracked in the highest systolic BP and pulse pressure levels from adolescence into young adulthood showed the thickest CIMT. Our findings strengthen the notion that elevated BP at adolescence and a relative increase in BP from adolescence to adulthood unfavorably affect cardiovascular risk, as indicated by increased CIMT.

Homocysteine, visceral adiposity-related novel cardiometabolic risk factors, and exaggerated blood pressure response to the exercise treadmill test.

PubMed

Türker Duyuler, Pinar; Duyuler, Serkan; Demir, Mevlüt; Uçar Elalmiş, Özgül; Güray, Ümit; İleri, Mehmet

2017-12-01

Exaggerated blood pressure response to exercise is a risk factor for the development of future hypertension. In this study, we aimed to investigate the association between homocysteine, epicardial fat thickness, nonalcoholic hepatic steatosis, and exaggerated blood pressure response to exercise. We included 44 normotensive and 40 patients with exaggerated blood pressure response to exercise who have normal resting blood pressure and without a previous diagnosis of hypertension. All patients underwent treadmill exercise test and clinical, ultrasonographic, and echocardiographic evaluation. Exaggerated blood pressure response to exercise is defined as peak exercise systolic blood pressure of at least 210 mmHg in men and at least 190 mmHg in women. Homocysteine and other biochemical parameters were determined with standardized automated laboratory tests. Mean age of all participants is 47.9±8.5 years, and 36 of 84 participants were female. The frequency of diabetes mellitus in both groups was similar (P=0.250). Homeostasis model assessment index-insulin resistance had a statistically insignificant trend to be higher in a patient with exercise hypertension (P=0.058). The nonalcoholic fatty liver was more frequent in patients with exercise hypertension (13.6 vs. 47.5%, P=0.002). Epicardial fat thickness was increased in patients with exercise hypertension (5.5±1.5 vs. 7.3±1.1 mm; P=0.001). However, homocysteine levels did not significantly differ between normotensive and exercise hypertensive patients [12.3 μmol/l (5.7-16.9 μmol/l) vs. 13 μmol/l (5.9-28.3 μmol/l); P=0.883]. In our study, homocysteine levels were not associated with exaggerated blood pressure response to exercise; however, fatty liver and epicardial fat thickness as visceral adiposity-related cardiometabolic risk factors were significantly related with exaggerated blood pressure response to exercise in patients without a previous diagnosis of hypertension.

Motivating patients to exercise: translating high blood pressure into equivalent risk of inactivity.

PubMed

Li, Chu-Shiu; Liu, Chwen-Chi; Tsai, Min-Kuang; Tai, Ya-Ping; Wai, Jackson Pui Man; Tsao, Chwen-Keng; Wen, Chi-Pang

2015-02-01

Even with the 2008 physical activity guidelines for Americans and the strong epidemiological evidence, physicians are not routinely emphasizing the importance of exercise. We try to explore an innovative way to communicate the benefits of physical activity in a term familiar to patients. A cohort of 470, 163 adults from a medical screening program in Taiwan were recruited between 1994 and 2008. Their vital status was followed up by matching with the National Death File. Individuals were classified as 'inactive', 'low active', or 'fully active', with 'fully active' meeting the current exercise recommendation of 150  min per week or more. Cox proportional model was used to calculate the hazard ratio. More than one-half of the cohort was inactive (54%), with one-quarter fully active (24%). One in seven was hypertensive (14%), defined as SBP at least 140  mmHg. Among the hypertensive individuals, mortality risks were increased by 37% for the inactive. Inactive individuals had higher all-cause mortality than active ones across all blood pressure (BP) levels. At 110-119  mmHg, the inactive had a risk as high as the risk at 155  mmHg, an increased mortality risk equivalent to a risk of BP increase of 41.2 mmHg. The mortality risk of being inactive was equivalent to an increase of around 40  mmHg in SBP or 20  mmHg in DBP, a number relevant to hypertensive patients. Appreciating this relationship may convince the inactive to start exercising, a behavior as important as controlling BP.

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…

Left ventricular mass, blood pressure, and lowered cognitive performance in the Framingham offspring.

PubMed

Elias, Merrill F; Sullivan, Lisa M; Elias, Penelope K; D'Agostino, Ralph B; Wolf, Philip A; Seshadri, Sudha; Au, Rhoda; Benjamin, Emelia J; Vasan, Ramachandran S

2007-03-01

The purpose of this study was to determine whether echocardiographic left ventricular mass is related to cognitive performance beyond casual blood pressure adjusting for the influence of other vascular risk factors. We used multivariable regression analyses to relate left ventricular mass assessed at a routine examination (1995-1998) to measures of cognitive ability obtained routinely (1998-2001) in 1673 Framingham Offspring Study participants (56% women; mean age: 57 years) free from stroke, transient ischemic attack, and dementia. We adjusted for the following covariates hierarchically: (1) age, education, sex, body weight, height, interval between left ventricular mass measurement and neuropsychological testing (basic model); (2) basic model+blood pressure+treatment for hypertension; and (3) basic model+blood pressure+treatment for hypertension+vascular risk factors and prevalent cardiovascular disease. For the basic model, left ventricular mass was inversely associated with abstract reasoning (similarities), visual-spatial memory and organization, and verbal memory. For the basic model+blood pressure+treatment for hypertension, left ventricular mass was inversely associated with similarities and visual-spatial memory and organization. For the basic+blood pressure+treatment for hypertension+risk factors+cardiovascular disease model, no significant associations were observed. Echocardiographic left ventricular mass is associated with cognitive performance beyond casual and time-averaged systolic blood pressure, but this association is attenuated and rendered nonsignificant with additional adjustment for cardiovascular risk factors and cardiovascular disease, thus suggesting that these variables play an important role in mediating the association between left ventricular mass and cognition.

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

USDA-ARS?s Scientific Manuscript database

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...

Clinical workflow for personalized foot pressure ulcer prevention.

PubMed

Bucki, M; Luboz, V; Perrier, A; Champion, E; Diot, B; Vuillerme, N; Payan, Y

2016-09-01

Foot pressure ulcers are a common complication of diabetes because of patient's lack of sensitivity due to neuropathy. Deep pressure ulcers appear internally when pressures applied on the foot create high internal strains nearby bony structures. Monitoring tissue strains in persons with diabetes is therefore important for an efficient prevention. We propose to use personalized biomechanical foot models to assess strains within the foot and to determine the risk of ulcer formation. Our workflow generates a foot model adapted to a patient's morphology by deforming an atlas model to conform it to the contours of segmented medical images of the patient's foot. Our biomechanical model is composed of rigid bodies for the bones, joined by ligaments and muscles, and a finite element mesh representing the soft tissues. Using our registration algorithm to conform three datasets, three new patient models were created. After applying a pressure load below these foot models, the Von Mises equivalent strains and "cluster volumes" (i.e. volumes of contiguous elements with strains above a given threshold) were measured within eight functionally meaningful foot regions. The results show the variability of both location and strain values among the three considered patients. This study also confirms that the anatomy of the foot has an influence on the risk of pressure ulcer. Copyright © 2016. Published by Elsevier Ltd.

The effect of Web-based Braden Scale training on the reliability and precision of Braden Scale pressure ulcer risk assessments.

PubMed

Magnan, Morris A; Maklebust, Joann

2008-01-01

To evaluate the effect of Web-based Braden Scale training on the reliability and precision of pressure ulcer risk assessments made by registered nurses (RN) working in acute care settings. Pretest-posttest, 2-group, quasi-experimental design. Five hundred Braden Scale risk assessments were made on 102 acute care patients deemed to be at various levels of risk for pressure ulceration. Assessments were made by RNs working in acute care hospitals at 3 different medical centers where the Braden Scale was in regular daily use (2 medical centers) or new to the setting (1 medical center). The Braden Scale for Predicting Pressure Sore Risk was used to guide pressure ulcer risk assessments. A Web-based version of the Detroit Medical Center Braden Scale Computerized Training Module was used to teach nurses correct use of the Braden Scale and selection of risk-based pressure ulcer prevention interventions. In the aggregate, RN generated reliable Braden Scale pressure ulcer risk assessments 65% of the time after training. The effect of Web-based Braden Scale training on reliability and precision of assessments varied according to familiarity with the scale. With training, new users of the scale made reliable assessments 84% of the time and significantly improved precision of their assessments. The reliability and precision of Braden Scale risk assessments made by its regular users was unaffected by training. Technology-assisted Braden Scale training improved both reliability and precision of risk assessments made by new users of the scale, but had virtually no effect on the reliability or precision of risk assessments made by regular users of the instrument. Further research is needed to determine best approaches for improving reliability and precision of Braden Scale assessments made by its regular users.

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.

Understanding the external pressure and behavior of commercial banks' environmental risk management: an empirical study undertaken in the Yangtze River delta of China.

PubMed

Liu, Yong; Lin, Zhongguo

2014-04-01

The present study employed a quantitative survey to ascertain whether the external pressure of environmental risk management (ERM) on commercial banks was a contributing factor to their ERM behavior. Data was obtained using questionnaires from 204 branches of commercial banks located in the Yangtze River Delta of China. The relationship between external pressure and behavior was tested using a linear structural relations model through path analysis. The results revealed that external pressure of ERM was significantly and positively related to the behavior and that pressure from governmental regulations was the most important contributing factor in the passive feedback behavior and preventive behavior of commercial banks. The pressure from markets was the most important contributing factor in banks' active participation behavior; the pressure from community and NGOs was the most important contributing factor in their enthusiastic behavior.

Prospective Chemistry Teachers' Mental Models of Vapor Pressure

ERIC Educational Resources Information Center

Tumay, Halil

2014-01-01

The main purpose of this study was to identify prospective chemistry teachers' mental models of vapor pressure. The study involved 85 students in the Chemistry Teacher Training Department of a state university in Turkey. Participants' mental models of vapor pressure were explored using a concept test that involved qualitative comparison tasks.…

Model-Based, Noninvasive Monitoring of Intracranial Pressure

DTIC Science & Technology

2013-07-01

patients. A physiologically based model relates ICP to simultaneously measured waveforms of arterial blood pressure ( ABP ), obtained via radial... ABP and CBFV are currently measured as the clinical standard of care. The project’s major accomplishments include: assembling a suitable system for...synchronized arterial blood pressure ( ABP ) and cerebral blood flow velocity (CBFV) waveform measurements that can be obtained quite routinely. Our processing

[A scale for the assessment of the risk of pressure sores in paediatric intensive care].

PubMed

Weigel, Virginie

2014-01-01

Pressure sores are a frequent complication in paediatric intensive care. A multi-disciplinary nursing team has drawn up an assessment scale for the risk of pressure sores and has put in place guidelines for caring for children in intensive care. Prevention actions are thereby adapted to each young patient.

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

USDA-ARS?s Scientific Manuscript database

This study examined whether previous observed inverse associations of dairy intake with systolic blood pressure and risk of hypertension were causal. A Mendelian randomization study was employed, using the single nucleotide polymorphism rs4988235 related to lactase persistence as an instrumental var...

Evaluating the risk of eye injuries: intraocular pressure during high speed projectile impacts.

PubMed

Duma, Stefan M; Bisplinghoff, Jill A; Senge, Danielle M; McNally, Craig; Alphonse, Vanessa D

2012-01-01

To evaluate the risk of eye injuries by determining intraocular pressure during high speed projectile impacts. A pneumatic cannon was used to impact eyes with a variety of projectiles at multiple velocities. Intraocular pressure was measured with a small pressure sensor inserted through the optic nerve. A total of 36 tests were performed on 12 porcine eyes with a range of velocities between 6.2 m/s and 66.5 m/s. Projectiles selected for the test series included a 6.35  mm diameter metal ball, a 9.25  mm diameter aluminum rod, and an 11.16  mm diameter aluminum rod. Experiments were designed with velocities in the range of projectile consumer products such as toy guns. A range of intraocular pressures ranged between 2017 mmHg to 26,426 mmHg (39 psi-511 psi). Four of the 36 impacts resulted in globe rupture. Intraocular pressures dramatically above normal physiological pressure were observed for high speed projectile impacts. These pressure data provide critical insight to chronic ocular injuries and long-term complications such as glaucoma and cataracts.

A Boussinesq-scaled, pressure-Poisson water wave model

NASA Astrophysics Data System (ADS)

Donahue, Aaron S.; Zhang, Yao; Kennedy, Andrew B.; Westerink, Joannes J.; Panda, Nishant; Dawson, Clint

2015-02-01

Through the use of Boussinesq scaling we develop and test a model for resolving non-hydrostatic pressure profiles in nonlinear wave systems over varying bathymetry. A Green-Nagdhi type polynomial expansion is used to resolve the pressure profile along the vertical axis, this is then inserted into the pressure-Poisson equation, retaining terms up to a prescribed order and solved using a weighted residual approach. The model shows rapid convergence properties with increasing order of polynomial expansion which can be greatly improved through the application of asymptotic rearrangement. Models of Boussinesq scaling of the fully nonlinear O (μ2) and weakly nonlinear O (μN) are presented, the analytical and numerical properties of O (μ2) and O (μ4) models are discussed. Optimal basis functions in the Green-Nagdhi expansion are determined through manipulation of the free-parameters which arise due to the Boussinesq scaling. The optimal O (μ2) model has dispersion accuracy equivalent to a Padé [2,2] approximation with one extra free-parameter. The optimal O (μ4) model obtains dispersion accuracy equivalent to a Padé [4,4] approximation with two free-parameters which can be used to optimize shoaling or nonlinear properties. In comparison to experimental results the O (μ4) model shows excellent agreement to experimental data.

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. Copyright © 2011 The Foundation for Professionals in Services for Adolescents. Published by Elsevier Ltd. All rights reserved.

Modelling oxygen self-diffusion in UO 2 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 UO 2 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 UO 2 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.

Cryogenic Pressure Control Modeling for Ellipsoidal Space Tanks in Reduced Gravity

NASA Technical Reports Server (NTRS)

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

2008-01-01

A computational fluid dynamics (CFD) model is developed to simulate pressure control of an ellipsoidal-shaped liquid hydrogen tank under external heating in low 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-3D software and simulates low gravity extrapolations of engineering checkout tests performed at Marshall Space Flight Center in 1999 in support of the Solar Thermal Upper Stage Technology Demonstrator (STUSTD) program. Model results illustrate that stable low gravity liquid-gas interfaces are maintained during all phases of the pressure control cycle. Steady and relatively smooth ullage pressurization rates are predicted. This work advances current low gravity CFD modeling capabilities for cryogenic pressure control and aids the development of a low cost CFD-based design process for space hardware.

Numerical Modeling of Self-Pressurization and Pressure Control by Thermodynamic Vent System in a Cryogenic Tank

NASA Technical Reports Server (NTRS)

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

2015-01-01

This paper presents a numerical model of a system-level test bed - the multipurpose hydrogen test bed (MHTB) using Generalized Fluid System Simulation Program (GFSSP). MHTB is representative in size and shape of a fully integrated space transportation vehicle liquid hydrogen (LH2) propellant tank and was tested at 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 thermo-fluid analysis of propulsion systems. GFSSP has been used to model the self-pressurization and ullage pressure control by Thermodynamic Vent System (TVS). A TVS typically includes a Joule-Thompson (J-T) expansion device, a two-phase heat exchanger, and a mixing pump and spray to extract thermal energy from the tank without significant loss of liquid propellant. Two GFSSP models (Self-Pressurization & TVS) were separately developed and tested and then integrated to simulate the entire system. Self-Pressurization model consists of multiple ullage nodes, propellant node and solid nodes; it computes the heat transfer through Multi-Layer Insulation blankets and calculates heat and mass transfer between ullage and liquid propellant and ullage and tank wall. TVS model calculates the flow through J-T valve, heat exchanger and spray and vent systems. Two models are integrated by exchanging data through User Subroutines of both models. The integrated models results have been compared with MHTB test data of 50% fill level. Satisfactory comparison was observed between test and numerical predictions.

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

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. 2010 Elsevier Inc. All rights reserved.

Residual Negative Pressure in Vacuum Tubes Might Increase the Risk of Spurious Hemolysis.

PubMed

Xiao, Tong-Tong; Zhang, Qiao-Xin; Hu, Jing; Ouyang, Hui-Zhen; Cai, Ying-Mu

2017-05-01

We planned a study to establish whether spurious hemolysis may occur when negative pressure remains in vacuum tubes. Four tubes with different vacuum levels (-54, -65, -74, and -86 kPa) were used to examine blood drawn from one healthy volunteer; the tubes were allowed to stand for different times (1, 2, 3, and 4 hours). The plasma was separated and immediately tested for free hemoglobin (FHb). Thirty patients were enrolled in a verification experiment. The degree of hemolysis observed was greater when the remaining negative pressure was higher. Significant differences were recorded in the verification experiment. The results suggest that residual negative pressure might increase the risk of spurious hemolysis.

Hamiltonian derivation of the nonhydrostatic pressure-coordinate model

NASA Astrophysics Data System (ADS)

Salmon, Rick; Smith, Leslie M.

1994-07-01

In 1989, the Miller-Pearce (MP) model for nonhydrostatic fluid motion governed by equations written in pressure coordinates was extended by removing the prescribed reference temperature, T(sub s)(p), while retaining the conservation laws and other desirable properties. It was speculated that this extension of the MP model had a Hamiltonian structure and that a slick derivation of the Ertel property could be constructed if the relevant Hamiltonian were known. In this note, the extended equations are derived using Hamilton's principle. The potential vorticity law arises from the usual particle-relabeling symmetry of the Lagrangian, and even the absence of sound waves is anticipated from the fact that the pressure inside the free energy G(p, theta) in the derived equation is hydrostatic and thus G is insensitive to local pressure fluctuations. The model extension is analogous to the semigeostrophic equations for nearly geostrophic flow, which do not incorporate a prescribed reference state, while the earlier MP model is analogous to the quasigeostrophic equations, which become highly inaccurate when the flow wanders from a prescribed state with nearly flat isothermal surfaces.

A stepped pressure profile model for internal transport barriers

NASA Astrophysics Data System (ADS)

Hole, Matthew; Hudson, Stuart; Dewar, Robert

2007-11-01

B ∇x et al We develop a multiple interface variational model, comprising multiple Taylor-relaxed plasma regions separated by ideal MHD barriers. The magnetic field in each region is Beltrami, = μ, and the pressure constant. Between these regions the pressure, field strength, and rotational transform may have step changes at the ideal barrier. A principle motivation is the development of a mathematically rigorous ideal MHD model to describe intrinsically 3D equilibria, with nonzero internal pressure, using robust KAM surfaces as the barriers. As each region is locally relaxed however, such a model may also yield reasons for existence of internal transport barriers (ITBs). Focusing on the latter, we build on Hole Nuc. Fus. 47, pp746-753, 2007, which recently studied the stability of a two-interface periodic-cylinder configuration. In this work, we perform a stability scan over pressure and for a two-interface configuration with no jump in , and compare the characteristics of stable equilibria to those of ITB's.

Cardiovascular risk and blood pressure control in a Spanish hypertensive population attended in a Primary Care setting. Data from the PRESCAP 2006 study.

PubMed

Rodriguez-Roca, Gustavo C; Llisterri-Caro, Jose L; Barrios-Alonso, Vivencio; Alonso-Moreno, Francisco J; Lou-Arnal, Salvador; Prieto-Diaz, Miguel A; Sanchez-Ruiz, Tomas; Dura-Belinchon, Rafael; Santos-Rodriguez, Jose A; Divison-Garrote, Juan A; Gonzalez-Segura, Diego; Banegas-Banegas, Jose R

2009-01-01

To analyse the cardiovascular risk of a broad sample of hypertensive patients and to examine whether there are differences in blood pressure control and associated factors according to the different cardiovascular risk categories. A total of 10,520 patients > or = 18 years old were included (mean age 64.6+/-11.3 years; 53.7% women). In this cohort, 3.3% were average risk, 22.6% low added risk, 22.2% moderate added risk, 33.5% high added risk and 18.4% very high added risk. Blood pressure was controlled in 41.4% (95% CI 40.5-42.4) of the total population, in 91.7% of patients with low added risk, in 19.4% with moderate added risk, in 27.4% with high added risk and in 6.8% with very high added risk. Diabetes was the factor most strongly associated with poor blood pressure control in patients with high to very high added risk (OR=7.2; p<0.0001). More than half of the hypertensive patients treated in primary health care have a high or very high added cardiovascular risk. In these patients, blood pressure control is inadequate and diabetes is associated with a sevenfold increase in the likelihood of poor blood pressure control.

Cost-effectiveness and value of information analysis of nutritional support for preventing pressure ulcers in high-risk patients: implement now, research later.

PubMed

Tuffaha, Haitham W; Roberts, Shelley; Chaboyer, Wendy; Gordon, Louisa G; Scuffham, Paul A

2015-04-01

Pressure ulcers are a major cause of mortality, morbidity, and increased healthcare cost. Nutritional support may reduce the incidence of pressure ulcers in hospitalised patients who are at risk of pressure ulcer and malnutrition. To evaluate the cost-effectiveness of nutritional support in preventing pressure ulcers in high-risk hospitalised patients, and to assess the value of further research to inform the decision to implement this intervention using value of information analysis (VOI). The analysis was from the perspective of Queensland Health, Australia using a decision model with evidence derived from a systematic review and meta-analysis. Resources were valued using 2014 prices and the time horizon of the analysis was one year. Monte Carlo simulation was used to estimate net monetary benefits (NB) and to calculate VOI measures. Compared with standard hospital diet, nutritional support was cost saving at AU$425 per patient, and more effective with an average 0.005 quality-adjusted life years (QALY) gained. At a willingness-to-pay of AU$50,000 per QALY, the incremental NB was AU$675 per patient, with a probability of 87 % that nutritional support is cost-effective. The expected value of perfect information was AU$5 million and the expected value of perfect parameter information was highest for the relative risk of developing a pressure ulcer at AU$2.5 million. For a future trial investigating the relative effectiveness of the interventions, the expected net benefit of research would be maximised at AU$100,000 with 1,200 patients in each arm if nutritional support was perfectly implemented. The opportunity cost of withholding the decision to implement the intervention until the results of the future study are available would be AU$14 million. Nutritional support is cost-effective in preventing pressure ulcers in high-risk hospitalised patients compared with standard diet. Future research to reduce decision uncertainty is worthwhile; however, given the

Pressurized storm sewer simulation : model enhancement.

DOT National Transportation Integrated Search

1991-01-01

A modified Pressurized Flow Simulation Model, PFSM, was developed and attached to the Federal Highway Administration, FHWA, Pool Funded PFP-HYDRA Package. Four hydrograph options are available for simulating inflow to a sewer system under surcharge o...

Contemporary model for cardiovascular risk prediction in people with type 2 diabetes.

PubMed

Kengne, Andre Pascal; Patel, Anushka; Marre, Michel; Travert, Florence; Lievre, Michel; Zoungas, Sophia; Chalmers, John; Colagiuri, Stephen; Grobbee, Diederick E; Hamet, Pavel; Heller, Simon; Neal, Bruce; Woodward, Mark

2011-06-01

Existing cardiovascular risk prediction equations perform non-optimally in different populations with diabetes. Thus, there is a continuing need to develop new equations that will reliably estimate cardiovascular disease (CVD) risk and offer flexibility for adaptation in various settings. This report presents a contemporary model for predicting cardiovascular risk in people with type 2 diabetes mellitus. A 4.5-year follow-up of the Action in Diabetes and Vascular disease: preterax and diamicron-MR controlled evaluation (ADVANCE) cohort was used to estimate coefficients for significant predictors of CVD using Cox models. Similar Cox models were used to fit the 4-year risk of CVD in 7168 participants without previous CVD. The model's applicability was tested on the same sample and another dataset. A total of 473 major cardiovascular events were recorded during follow-up. Age at diagnosis, known duration of diabetes, sex, pulse pressure, treated hypertension, atrial fibrillation, retinopathy, HbA1c, urinary albumin/creatinine ratio and non-HDL cholesterol at baseline were significant predictors of cardiovascular events. The model developed using these predictors displayed an acceptable discrimination (c-statistic: 0.70) and good calibration during internal validation. The external applicability of the model was tested on an independent cohort of individuals with type 2 diabetes, where similar discrimination was demonstrated (c-statistic: 0.69). Major cardiovascular events in contemporary populations with type 2 diabetes can be predicted on the basis of routinely measured clinical and biological variables. The model presented here can be used to quantify risk and guide the intensity of treatment in people with diabetes.

Breast cancer risk prediction using a clinical risk model and polygenic risk score.

PubMed

Shieh, Yiwey; Hu, Donglei; Ma, Lin; Huntsman, Scott; Gard, Charlotte C; Leung, Jessica W T; Tice, Jeffrey A; Vachon, Celine M; Cummings, Steven R; Kerlikowske, Karla; Ziv, Elad

2016-10-01

Breast cancer risk assessment can inform the use of screening and prevention modalities. We investigated the performance of the Breast Cancer Surveillance Consortium (BCSC) risk model in combination with a polygenic risk score (PRS) comprised of 83 single nucleotide polymorphisms identified from genome-wide association studies. We conducted a nested case-control study of 486 cases and 495 matched controls within a screening cohort. The PRS was calculated using a Bayesian approach. The contributions of the PRS and variables in the BCSC model to breast cancer risk were tested using conditional logistic regression. Discriminatory accuracy of the models was compared using the area under the receiver operating characteristic curve (AUROC). Increasing quartiles of the PRS were positively associated with breast cancer risk, with OR 2.54 (95 % CI 1.69-3.82) for breast cancer in the highest versus lowest quartile. In a multivariable model, the PRS, family history, and breast density remained strong risk factors. The AUROC of the PRS was 0.60 (95 % CI 0.57-0.64), and an Asian-specific PRS had AUROC 0.64 (95 % CI 0.53-0.74). A combined model including the BCSC risk factors and PRS had better discrimination than the BCSC model (AUROC 0.65 versus 0.62, p = 0.01). The BCSC-PRS model classified 18 % of cases as high-risk (5-year risk ≥3 %), compared with 7 % using the BCSC model. The PRS improved discrimination of the BCSC risk model and classified more cases as high-risk. Further consideration of the PRS's role in decision-making around screening and prevention strategies is merited.

Breast Cancer Risk Prediction Using a Clinical Risk Model and Polygenic Risk Score

PubMed Central

Shieh, Yiwey; Hu, Donglei; Ma, Lin; Huntsman, Scott; Gard, Charlotte C.; Leung, Jessica W.T.; Tice, Jeffrey A.; Vachon, Celine M.; Cummings, Steven R.; Kerlikowske, Karla; Ziv, Elad

2016-01-01

Purpose Breast cancer risk assessment can inform the use of screening and prevention modalities. We investigated the performance of the Breast Cancer Surveillance Consortium (BCSC) risk model in combination with a polygenic risk score (PRS) comprised of 83 single nucleotide polymorphisms identified from genome wide association studies. Methods We conducted a nested case-control study of 486 cases and 495 matched controls within a screening cohort. The PRS was calculated using a Bayesian approach. The contributions of the PRS and variables in the BCSC model to breast cancer risk were tested using conditional logistic regression. Discriminatory accuracy of the models was compared using the area under the receiver operating characteristic curve (AUROC). Results Increasing quartiles of the PRS were positively associated with breast cancer risk, with OR 2.54 (95% CI 1.69-3.82) for breast cancer in the highest versus lowest quartile. In a multivariable model, the PRS, family history, and breast density remained strong risk factors. The AUROC of the PRS was 0.60 (95% CI 0.57-0.64), and an Asian-specific PRS had AUROC 0.64 (95% CI 0.53-0.74). A combined model including the BCSC risk factors and PRS had better discrimination than the BCSC model (AUROC 0.65 versus 0.62, p = 0.01). The BCSC-PRS model classified 18% of cases as high-risk (5-year risk ≥ 3%), compared with 7% using the BCSC model. Conclusion The PRS improved discrimination of the BCSC risk model and classified more cases as high-risk. Impact Further consideration of the PRS's role in decision-making around screening and prevention strategies is merited. PMID:27565998

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.

Changing the "Normal Range" for Blood Pressure from 140/90 to 130/Any Improves Risk Assessment.

PubMed

Fulks, Michael; Stout, Robert L; Dolan, Vera F

2015-01-01

Objective .- Redefine the "normal" reference range for blood pressure from <140/90 to one that more effectively identifies individuals with increased mortality risk. Method .- Data from the recently published 2014 CRL blood pressure study was used. It includes 2,472,706 life insurance applicants tested by Clinical Reference Laboratory from 1993 to 2007 with follow-up for vital status using the September 2011 Social Security Death Master File. Various upper limits of blood pressure (BP in mm Hg) were evaluated to determine if any was superior to the current, commonly used limit of 140/90 in identifying individuals with increased mortality risk. Results .- An alternative reference range using a systolic BP (SBP) <130 with any diastolic BP (DBP) included 84% of life insurance applicants. It had a lower mortality rate and narrower range of relative risk than <140/90, including 89% as many applicants but only 68% as many deaths. This pattern of lives and deaths was consistent across age and sex. Conclusion .- Switching to a "normal" reference range of SBP <130 offers superior risk assessment relative to using BP <140/90 while still including a sufficient percentage of the population.

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.

Sport Participation and Metabolic Risk During Adolescent Years: A Structured Equation Model.

PubMed

Werneck, AndréOliveira; da Silva, Danilo Rodrigues Pereira; Fernandes, Rômulo Araújo; Ronque, EnioRicardoVaz; Coelho-E-Silva, Manuel J; Cyrino, Edilson Serpeloni

2018-06-21

Sports practice during childhood can influence health indicators in later ages through direct and indirect pathways. Thus, this study aimed to test direct and indirect pathways to the association between sports practice in childhood and metabolic risk in adolescence, adopting physical activity, adiposity, and cardiorespiratory fitness at adolescence as potential mediators. This cross-sectional study with retrospective information was conducted with 991 adolescents (579 girls, 412 boys) aged 10 to 16 y. Sports activity was self-reported in childhood (retrospective data) and physical activity evaluated in adolescence through questionnaires. Somatic maturation (Mirwald method), cardiorespiratory fitness (20-m shuttle-run test), body fat (skinfolds), waist circumference, blood pressure (automatic instrument) and blood variables (fasting glucose, HDL cholesterol, and triglycerides) were measured at adolescence. Waist circumference, blood pressure and blood variables composed the metabolic risk score. Structured equation modeling was adopted. In both sexes, the relationship between sports practice at childhood and metabolic risk was fully mediated by habitual physical activity, which is related to the obesity construct and cardiorespiratory fitness. Obesity was associated with metabolic risk in boys (β=0.062; p<0.001) and girls (β=0.047; p<0.001). The relationship between sports practice in childhood and metabolic risk in adolescence was mediated by physical activity, obesity, and cardiorespiratory fitness. © Georg Thieme Verlag KG Stuttgart · New York.

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.

Different components of blood pressure are associated with increased risk of atherosclerotic cardiovascular disease versus heart failure in advanced chronic kidney disease

PubMed Central

Bansal, Nisha; McCulloch, Charles E.; Lin, Feng; Robinson-Cohen, Cassianne; Rahman, Mahboob; Kusek, John W.; Anderson, Amanda H.; Xie, Dawei; Townsend, Raymond R.; Lora, Claudia M.; Wright, Jackson; Go, Alan S.; Ojo, Akinlolu; Alper, Arnold; Lustigova, Eva; Cuevas, Magda; Kallem, Radhakrishna; Hsu, Chi-yuan

2016-01-01

Blood pressure is a modifiable risk for cardiovascular disease (CVD). Among hemodialysis patients, there is a U-shaped association between blood pressure and risk of death. However, few studies have examined the association between blood pressure and CVD in patients with stage 4 and 5 chronic kidney disease. Here we studied 1,795 Chronic Renal Insufficiency Cohort (CRIC) Study participants with estimated glomerular filtration rate under 30 ml/min/1.73 m2 and not on dialysis. The association of systolic (SBP), diastolic (DBP) and pulse pressure with risk of physician-adjudicated atherosclerotic CVD (stroke, myocardial infarction or peripheral arterial disease) and heart failure were tested using Cox regression adjusted for demographics, comorbidity and medications. There was a significant association with higher SBP (adjusted hazard ratio 2.04 [95% confidence interval: 1.46, 2.84]) for SBP over 140 vs under 120 mmHg, higher DBP (2.52 [1.54, 4.11]) for DBP over 90 vs under 80 mmHg and higher pulse pressure (2.67 [1.82, 3.92]) for pulse pressure over 68 vs under 51 mmHg with atherosclerotic CVD. For heart failure, there was a significant association with higher pulse pressure only (1.42 [1.05, 1.92]) for pulse pressure over 68 vs under 51 mmHg, but not for SBP or DBP. Thus, among participants with stage 4 and 5 chronic kidney disease, there was an independent association between higher SBP, DBP and pulse pressure with risk of atherosclerotic CVD, while only higher pulse pressure was independently associated with greater risk of heart failure. Further trials are needed to determine whether aggressive reduction of blood pressure reduces the risk of CVD events in patients with stage 4 and 5 chronic kidney disease. PMID:27717485

One-dimensional pressure transfer models for acoustic-electric transmission channels

NASA Astrophysics Data System (ADS)

Wilt, K. R.; Lawry, T. J.; Scarton, H. A.; Saulnier, G. J.

2015-09-01

A method for modeling piezoelectric-based ultrasonic acoustic-electric power and data transmission channels is presented. These channels employ piezoelectric disk transducers to convey signals across a series of physical layers using ultrasonic waves. This model decomposes the mechanical pathway of the signal into individual ultrasonic propagation layers which are generally independent of the layer's adjacent domains. Each layer is represented by a two-by-two traveling pressure wave transfer matrix which relates the forward and reverse pressure waves on one side of the layer to the pressure waves on the opposite face, where each face is assumed to be in contact with a domain of arbitrary reference acoustic impedance. A rigorous implementation of ultrasonic beam spreading is introduced and implemented within applicable domains. Compatible pressure-wave models for piezoelectric transducers are given, which relate the electric voltage and current interface of the transducer to the pressure waves on one mechanical interface while also allowing for passive acoustic loading of the secondary mechanical interface. It is also shown that the piezoelectric model's electrical interface is compatible with transmission line parameters (ABCD-parameters), allowing for connection of electronic components and networks. The model is shown to be capable of reproducing the behavior of realistic physical channels.

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.

On the permanent hip-stabilizing effect of atmospheric pressure.

PubMed

Prietzel, Torsten; Hammer, Niels; Schleifenbaum, Stefan; Kaßebaum, Eric; Farag, Mohamed; von Salis-Soglio, Georg

2014-08-22

Hip joint dislocations related to total hip arthroplasty (THA) are a common complication especially in the early postoperative course. The surgical approach, the alignment of the prosthetic components, the range of motion and the muscle tone are known factors influencing the risk of dislocation. A further factor that is discussed until today is atmospheric pressure which is not taken into account in the present THA concepts. The aim of this study was to investigate the impact of atmospheric pressure on hip joint stability. Five joint models (Ø 28-44 mm), consisting of THA components were hermetically sealed with a rubber capsule, filled with a defined amount of fluid and exposed to varying ambient pressure. Displacement and pressure sensors were used to record the extent of dislocation related to intraarticular and ambient pressure. In 200 experiments spontaneous dislocations of the different sized joint models were reliably observed once the ambient pressure was lower than 6.0 kPa. Increasing the ambient pressure above 6.0 kPa immediately and persistently reduced the joint models until the ambient pressure was lowered again. Displacement always exceeded half the diameter of the joint model and was independent of gravity effects. This experimental study gives strong evidence that the hip joint is permanently stabilized by atmospheric pressure, confirming the theories of Weber and Weber (1836). On basis of these findings the use of larger prosthetic heads, capsular repair and the deployment of an intracapsular Redon drain are proposed to substantially decrease the risk of dislocation after THA. Copyright © 2014 Elsevier Ltd. All rights reserved.

The cardiovascular event reduction tool (CERT)--a simplified cardiac risk prediction model developed from the West of Scotland Coronary Prevention Study (WOSCOPS).

PubMed

L'Italien, G; Ford, I; Norrie, J; LaPuerta, P; Ehreth, J; Jackson, J; Shepherd, J

2000-03-15

The clinical decision to treat hypercholesterolemia is premised on an awareness of patient risk, and cardiac risk prediction models offer a practical means of determining such risk. However, these models are based on observational cohorts where estimates of the treatment benefit are largely inferred. The West of Scotland Coronary Prevention Study (WOSCOPS) provides an opportunity to develop a risk-benefit prediction model from the actual observed primary event reduction seen in the trial. Five-year Cox model risk estimates were derived from all WOSCOPS subjects (n = 6,595 men, aged 45 to 64 years old at baseline) using factors previously shown to be predictive of definite fatal coronary heart disease or nonfatal myocardial infarction. Model risk factors included age, diastolic blood pressure, total cholesterol/ high-density lipoprotein ratio (TC/HDL), current smoking, diabetes, family history of fatal coronary heart disease, nitrate use or angina, and treatment (placebo/ 40-mg pravastatin). All risk factors were expressed as categorical variables to facilitate risk assessment. Risk estimates were incorporated into a simple, hand-held slide rule or risk tool. Risk estimates were identified for 5-year age bands (45 to 65 years), 4 categories of TC/HDL ratio (<5.5, 5.5 to <6.5, 6.5 to <7.5, > or = 7.5), 2 levels of diastolic blood pressure (<90, > or = 90 mm Hg), from 0 to 3 additional risk factors (current smoking, diabetes, family history of premature fatal coronary heart disease, nitrate use or angina), and pravastatin treatment. Five-year risk estimates ranged from 2% in very low-risk subjects to 61% in the very high-risk subjects. Risk reduction due to pravastatin treatment averaged 31%. Thus, the Cardiovascular Event Reduction Tool (CERT) is a risk prediction model derived from the WOSCOPS trial. Its use will help physicians identify patients who will benefit from cholesterol reduction.

Assessing the public health risk of microbial intrusion events in distribution systems: conceptual model, available data, and challenges.

PubMed

Besner, Marie-Claude; Prévost, Michèle; Regli, Stig

2011-01-01

Low and negative pressure events in drinking water distribution systems have the potential to result in intrusion of pathogenic microorganisms if an external source of contamination is present (e.g., nearby leaking sewer main) and there is a pathway for contaminant entry (e.g., leaks in drinking water main). While the public health risk associated with such events is not well understood, quantitative microbial risk assessment can be used to estimate such risk. A conceptual model is provided and the state of knowledge, current assumptions, and challenges associated with the conceptual model parameters are presented. This review provides a characterization of the causes, magnitudes, durations and frequencies of low/negative pressure events; pathways for pathogen entry; pathogen occurrence in external sources of contamination; volumes of water that may enter through the different pathways; fate and transport of pathogens from the pathways of entry to customer taps; pathogen exposure to populations consuming the drinking water; and risk associated with pathogen exposure. Copyright © 2010 Elsevier Ltd. All rights reserved.

Perceived psychological pressure at work, social class, and risk of stroke: a 30-year follow-up in Copenhagen male study.

PubMed

Suadicani, Poul; Andersen, Lars L; Holtermann, Andreas; Mortensen, Ole S; Gyntelberg, Finn

2011-12-01

Investigate if the association between perceived psychological work pressure and risk of stroke is modified by socioeconomic status. Thirty-year follow-up of 4943 middle-aged men without cardiovascular disease. In the higher social classes (I, II, and III), perceived regular exposure to psychological work pressure was common and a significant predictor of stroke; almost 10% of the stroke events could be attributed to this exposure in the higher social classes; among lower social classes (IV and V), perceived psychological pressure was no predictor at all. Regular psychological work pressure is a highly prevalent and independent risk factor for stroke among men in higher social classes. In contrast, no association to stroke risk was found among low social class men.

Transfer function-derived central pressure and cardiovascular disease events: the Framingham Heart Study.

PubMed

Mitchell, Gary F; Hwang, Shih-Jen; Larson, Martin G; Hamburg, Naomi M; Benjamin, Emelia J; Vasan, Ramachandran S; Levy, Daniel; Vita, Joseph A

2016-08-01

Relations between central pulse pressure (PP) or pressure amplification and major cardiovascular disease (CVD) events are controversial. Estimates of central aortic pressure derived using radial artery tonometry and a generalized transfer function may better predict CVD risk beyond the predictive value of brachial SBP. Augmentation index, central SBP, central PP, and central-to-peripheral PP amplification were evaluated using radial artery tonometry and a generalized transfer function as implemented in the SphygmoCor device (AtCor Medical, Itasca, Illinois, USA). We used proportional hazards models to examine relations between central hemodynamics and first-onset major CVD events in 2183 participants (mean age 62 years, 58% women) in the Framingham Heart Study. During median follow-up of 7.8 (limits 0.2-8.9) years, 149 participants (6.8%) had an incident event. Augmentation index (P = 0.6), central aortic systolic pressure (P = 0.20), central aortic PP (P = 0.24), and PP amplification (P = 0.15) were not related to CVD events in multivariable models that adjusted for age, sex, brachial cuff systolic pressure, use of antihypertensive therapy, total and high-density lipoprotein cholesterol concentrations, smoking, and presence of diabetes. In a model that included standard risk factors, model fit was improved (P = 0.03) when brachial systolic pressure was added after central, whereas model fit was not improved (P = 0.30) when central systolic pressure was added after brachial. After considering standard risk factors, including brachial cuff SBP, augmentation index, central PP and PP amplification derived using radial artery tonometry, and a generalized transfer function were not predictive of CVD risk.

Subepidermal moisture detection of pressure induced tissue damage on the trunk: The pressure ulcer detection study outcomes.

PubMed

Bates-Jensen, Barbara M; McCreath, Heather E; Patlan, Anabel

2017-05-01

We examined the relationship between subepidermal moisture measured using surface electrical capacitance and visual skin assessment of pressure ulcers at the trunk location (sacral, ischial tuberosities) in 417 nursing home residents residing in 19 facilities. Participants were on average older (mean age of 77 years), 58% were female, over half were ethnic minorities (29% African American, 12% Asian American, and 21% Hispanic), and at risk for pressure ulcers (mean score for Braden Scale for Predicting Pressure Ulcer Risk of 15.6). Concurrent visual assessments and subepidermal moisture were obtained at the sacrum and right and left ischium weekly for 16 weeks. Visual assessment was categorized as normal, erythema, stage 1 pressure ulcer, Deep Tissue Injury or stage 2+ pressure ulcer using the National Pressure Ulcer Advisory Panel 2009 classification system. Incidence of any skin damage was 52%. Subepidermal moisture was measured with a dermal phase meter where higher readings indicate greater moisture (range: 0-70 tissue dielectric constant), with values increasing significantly with the presence of skin damage. Elevated subepidermal moisture values co-occurred with concurrent skin damage in generalized multinomial logistic models (to control for repeated observations) at the sacrum, adjusting for age and risk. Higher subepidermal moisture values were associated with visual damage 1 week later using similar models. Threshold values for subepidermal moisture were compared to visual ratings to predict skin damage 1 week later. Subepidermal moisture of 39 tissue dielectric constant units predicted 41% of future skin damage while visual ratings predicted 27%. Thus, this method of detecting early skin damage holds promise for clinicians, especially as it is objective and equally valid for all groups of patients. © 2017 by the Wound Healing Society.

Association of Pregnancy Complications and Characteristics with Future Risk of Elevated Blood Pressure: The Västerbotten Intervention Programme

PubMed Central

Parikh, Nisha I.; Norberg, Margareta; Ingelsson, Erik; Cnattingius, Sven; Vasan, Ramachandran S.; Domellöf, Magnus; Jansson, Jan Håkan; Edstedt Bonamy, Anna-Karin

2017-01-01

Pregnancy characteristics are associated with risk of cardiovascular diseases, but their independent associations with hypertension or blood pressure levels remain uncertain. We linked the Swedish Medical Birth Register with Västerbotten Intervention Programme data (Northern Sweden). Using linear and logistic regression, we related pregnancy factors in any prior pregnancy with blood pressure and hypertension at age 40 years in 15,896 parous women free of prepregnancy hypertension. Pregnancy factors included parity, age at first delivery, preeclampsia, gestational diabetes, placental abruption, shortest gestational age small for gestational age baby (SGA; < 3rd percentile for birth weight) or stillbirth. We defined hypertension as systolic BP ≥ 140 and/or DBP ≥ 90 mmHg and/or antihypertensive use. Multivariable models were adjusted for all pregnancy factors and potential lifestyle and sociodemographic confounders. At age 40 years, 1,535 women (9.6%) had hypertension. In multivariable models, lower parity, younger age at first birth, preeclampsia, SGA, and placental abruption were independently associated with higher systolic and/or diastolic blood pressure levels at age 40 years. Younger age at first birth, preeclampsia, gestational age <32 versus ≥ 37 weeks and SGA, were independently associated with hypertension. Our findings raise the possibility that earlier and more frequent BP screening may be desirable in women with these pregnancy characteristics. PMID:28137991

The effects of nursing activities on the intra-abdominal pressure of patients at risk for intra-abdominal hypertension.

PubMed

Lee, Rosemary K

2017-01-01

Intra-abdominal hypertension (IAH) occurs frequently in critically ill patients, and adds to their morbidity and mortality. There is no published evidence on the effects of nursing activities on the intra-abdominal pressure (IAP) for patients at risk of IAH. The purpose of this study was to identify the effects of hygiene care on the IAP of patients at risk for IAH. Hygiene care was provided to 34 at-risk patients. IAP was measured prior to initiating the hygiene care, immediately after and 10 minutes later. This was a quasi-experimental, pre-test/ post-test design. The 10 minute post-hygiene care measurement of the IAP was significantly lower than the pre or immediate post-measurement of the IAP. There were no significant changes in the mean arterial pressure (MAP) or the abdominal perfusion pressure (APP). It is safe and possibly therapeutic to provide hygiene care to patients at risk for IAH.

Modeling multisystem biological risk in young adults: The Coronary Artery Risk Development in Young Adults Study.

PubMed

Seeman, Teresa; Gruenewald, Tara; Karlamangla, Arun; Sidney, Steve; Liu, Kiang; McEwen, Bruce; Schwartz, Joseph

2010-01-01

Although much prior research has focused on identifying the roles of major regulatory systems in health risks, the concept of allostatic load (AL) focuses on the importance of a more multisystems view of health risks. How best to operationalize allostatic load, however, remains the subject of some debate. We sought to test a hypothesized metafactor model of allostatic load composed of a number of biological system factors, and to investigate model invariance across sex and ethnicity. Biological data from 782 men and women, aged 32-47, from the Oakland, CA and Chicago, IL sites of the Coronary Artery Risk Development in Young Adults Study (CARDIA) were collected as part of the Year 15exam in 2000. These include measures of blood pressure, metabolic parameters (glucose, insulin, lipid profiles, and waist circumference), markers of inflammation (interleukin-6, C-reactive protein, and fibrinogen), heart rate variability, sympathetic nervous system activity (12-hr urinary norepinephrine and epinephrine) and hypothalamic-pituitary-adrenal axis activity (diurnal salivary free cortisol). A "metafactor" model of AL as an aggregate measure of six underlying latent biological subfactors was found to fit the data, with the metafactor structure capturing 84% of variance of all pairwise associations among biological subsystems. There was little evidence of model variance across sex and/or ethnicity. These analyses extend work operationalizing AL as a multisystems index of biological dysregulation, providing initial support for a model of AL as a metaconstruct of inter-relationships among multiple biological regulatory systems, that varies little across sex or ethnicity.

A Novel Early Pregnancy Risk Prediction Model for Gestational Diabetes Mellitus.

PubMed

Sweeting, Arianne N; Wong, Jencia; Appelblom, Heidi; Ross, Glynis P; Kouru, Heikki; Williams, Paul F; Sairanen, Mikko; Hyett, Jon A

2018-06-13

Accurate early risk prediction for gestational diabetes mellitus (GDM) would target intervention and prevention in women at the highest risk. We evaluated novel biomarker predictors to develop a first-trimester risk prediction model in a large multiethnic cohort. Maternal clinical, aneuploidy and pre-eclampsia screening markers (PAPP-A, free hCGβ, mean arterial pressure, uterine artery pulsatility index) were measured prospectively at 11-13+6 weeks' gestation in 980 women (248 with GDM; 732 controls). Nonfasting glucose, lipids, adiponectin, leptin, lipocalin-2, and plasminogen activator inhibitor-2 were measured on banked serum. The relationship between marker multiples-of-the-median and GDM was examined with multivariate regression. Model predictive performance for early (< 24 weeks' gestation) and overall GDM diagnosis was evaluated by receiver operating characteristic curves. Glucose, triglycerides, leptin, and lipocalin-2 were higher, while adiponectin was lower, in GDM (p < 0.05). Lipocalin-2 performed best in Caucasians, and triglycerides in South Asians with GDM. Family history of diabetes, previous GDM, South/East Asian ethnicity, parity, BMI, PAPP-A, triglycerides, and lipocalin-2 were significant independent GDM predictors (all p < 0.01), achieving an area under the curve of 0.91 (95% confidence interval [CI] 0.89-0.94) overall, and 0.93 (95% CI 0.89-0.96) for early GDM, in a combined multivariate prediction model. A first-trimester risk prediction model, which incorporates novel maternal lipid markers, accurately identifies women at high risk of GDM, including early GDM. © 2018 S. Karger AG, Basel.

Prediction of friction pressure drop for low pressure two-phase flows on the basis of approximate analytical models

NASA Astrophysics Data System (ADS)

Zubov, N. O.; Kaban'kov, O. N.; Yagov, V. V.; Sukomel, L. A.

2017-12-01

Wide use of natural circulation loops operating at low redused pressures generates the real need to develop reliable methods for predicting flow regimes and friction pressure drop for two-phase flows in this region of parameters. Although water-air flows at close-to-atmospheric pressures are the most widely studied subject in the field of two-phase hydrodynamics, the problem of reliably calculating friction pressure drop can hardly be regarded to have been fully solved. The specific volumes of liquid differ very much from those of steam (gas) under such conditions, due to which even a small change in flow quality may cause the flow pattern to alter very significantly. Frequently made attempts to use some or another universal approach to calculating friction pressure drop in a wide range of steam quality values do not seem to be justified and yield predicted values that are poorly consistent with experimentally measured data. The article analyzes the existing methods used to calculate friction pressure drop for two-phase flows at low pressures by comparing their results with the experimentally obtained data. The advisability of elaborating calculation procedures for determining the friction pressure drop and void fraction for two-phase flows taking their pattern (flow regime) into account is demonstrated. It is shown that, for flows characterized by low reduced pressures, satisfactory results are obtained from using a homogeneous model for quasi-homogeneous flows, whereas satisfactory results are obtained from using an annular flow model for flows characterized by high values of void fraction. Recommendations for making a shift from one model to another in carrying out engineering calculations are formulated and tested. By using the modified annular flow model, it is possible to obtain reliable predictions for not only the pressure gradient but also for the liquid film thickness; the consideration of droplet entrainment and deposition phenomena allows reasonable

A risk tertiles model for predicting mortality in patients with acute respiratory distress syndrome: age, plateau pressure, and P(aO(2))/F(IO(2)) at ARDS onset can predict mortality.

PubMed

Villar, Jesús; Pérez-Méndez, Lina; Basaldúa, Santiago; Blanco, Jesús; Aguilar, Gerardo; Toral, Darío; Zavala, Elizabeth; Romera, Miguel A; González-Díaz, Gumersindo; Nogal, Frutos Del; Santos-Bouza, Antonio; Ramos, Luís; Macías, Santiago; Kacmarek, Robert M

2011-04-01

Predicting mortality has become a necessary step for selecting patients for clinical trials and defining outcomes. We examined whether stratification by tertiles of respiratory and ventilatory variables at the onset of acute respiratory distress syndrome (ARDS) identifies patients with different risks of death in the intensive care unit. We performed a secondary analysis of data from 220 patients included in 2 multicenter prospective independent trials of ARDS patients mechanically ventilated with a lung-protective strategy. Using demographic, pulmonary, and ventilation data collected at ARDS onset, we derived and validated a simple prediction model based on a population-based stratification of variable values into low, middle, and high tertiles. The derivation cohort included 170 patients (all from one trial) and the validation cohort included 50 patients (all from a second trial). Tertile distribution for age, plateau airway pressure (P(plat)), and P(aO(2))/F(IO(2)) at ARDS onset identified subgroups with different mortalities, particularly for the highest-risk tertiles: age (> 62 years), P(plat) (> 29 cm H(2)O), and P(aO(2))/F(IO(2)) (< 112 mm Hg). Risk was defined by the number of coexisting high-risk tertiles: patients with no high-risk tertiles had a mortality of 12%, whereas patients with 3 high-risk tertiles had 90% mortality (P < .001). A prediction model based on tertiles of patient age, P(plat), and P(aO(2))/F(IO(2)) at the time the patient meets ARDS criteria identifies patients with the lowest and highest risk of intensive care unit death.

[The absence of risk factors for coronary disease in Yanomami Indians and the influence of acculturation on arterial pressure].

PubMed

Mancilha-Carvalho, J J; Carvalho, J V; Lima, J A; Sousa e Silva, N A

1992-10-01

To investigate the hypothesis that hypertension and coronary heart disease are "civilization diseases", analyzing the distribution of their antecedents in an Indian population and observing the influence of acculturation on blood pressure. Seven hundred and twenty-five Yanomami Indians of both sexes, ages above 14 years, inhabitants of eight villages in Roraima and Amazonas states were examined. Measures related to all classical coronary risk factors were carried out and urine samples were collected to measure electrolytes. None of the known coronary risk factors were found. The blood pressure levels were low and did not increase with increasing age. There was influence of acculturation on blood pressure and it was in part mediated by increase in body weight and sodium intake. The absence of hypertension and other coronary risk factors and the increase of blood pressure with acculturation, among an isolated population, strongly suggest that these diseases are "civilization diseases".

Modeling the pharyngeal pressure during adult nasal high flow therapy.

PubMed

Kumar, Haribalan; Spence, Callum J T; Tawhai, Merryn H

2015-12-01

Subjects receiving nasal high flow (NHF) via wide-bore nasal cannula may experience different levels of positive pressure depending on the individual response to NHF. In this study, airflow in the nasal airway during NHF-assisted breathing is simulated and nasopharyngeal airway pressure numerically computed, to determine whether the relationship between NHF and pressure can be described by a simple equation. Two geometric models are used for analysis. In the first, 3D airway geometry is reconstructed from computed tomography images of an adult nasal airway. For the second, a simplified geometric model is derived that has the same cross-sectional area as the complex model, but is more readily amenable to analysis. Peak airway pressure is correlated as a function of nasal valve area, nostril area and cannula flow rate, for NHF rates of 20, 40 and 60 L/min. Results show that airway pressure is related by a power law to NHF rate, valve area, and nostril area. Copyright © 2015 Elsevier B.V. All rights reserved.

Positional change in blood pressure and 8-year risk of hypertension: the CARDIA Study.

PubMed

Thomas, Randal J; Liu, Kiang; Jacobs, David R; Bild, Diane E; Kiefe, Catarina I; Hulley, Stephen B

2003-08-01

To assess the relationship between positional blood pressure change and 8-year incidence of hypertension in a biracial cohort of young adults. Participants from the Coronary Artery Risk Development in Young Adults (CARDIA) study with complete data from year 2 (1987-1988), year 5 (1990-1991), year 7 (1992-1993), and year 10 (1995-1996) examinations were included (N = 2781). Participants were classified into 3 groups based on their year 2 systolic blood pressure response to standing: drop, a decrease in systolic blood pressure of more than 5 mm Hg; same, a change of between -5 and +5 mm Hg; and rise, more than 5-mm Hg increase. The number of participants in each group was as follows: drop, 741; same, 1590; and rise, 450. The 8-year incidence of hypertension was 8.4% in the drop group, 6.8% in the same group, and 12.4% in the rise group (P < .001). Adjusted odds ratios for developing hypertension during the follow-up period in the rise group vs the same group were as follows: in black men, 2.85 (95% confidence interval [CI], 1.43-5.69), in black women, 2.47 (95% CI, 1.19-5.11), in white men, 2.17 (95% CI, 1.00-4.73), and in white women, 4.74 (95% CI, 1.11-20.30). A greater than 5-mm Hg increase in blood pressure on standing identified a group of young adults at increased risk of developing hypertension within 8 years. These findings support a physiologic link between sympathetic nervous system reactivity and risk of hypertension in young adults.

Assessment of nurses' knowledge on evidence-based preventive practices for pressure ulcer risk reduction in patients with impaired mobility.

PubMed

Akese, M I; Adejumo, P O; Ilesanmi, R E; Obilor, H N

2014-09-01

The increase in the prevalence of pressure ulcer among patients with impaired physical mobility has currently been associated with nurses' inadequate knowledge of preventive interventions. To assess nurses' knowledge of pressure ulcer identification/staging, risk factors and evidence-based preventive practices. This descriptive study was carried out at the University Teaching Hospital Maiduguri (UMTH), Borno State, Nigeria. Total sampling technique was utilized in the recruitment of the study participants. An adapted 75-item-pressure ulcer questionnaire was used for data collection. The data were analyzed using SPSS version 16. The hypotheses on nurses' knowledge were tested at 0.05 level of significance using Chi square test. A total of 219 nurses participated in this study with response rate of 68.0%. The nurses' years of professional practice ranged from 1 to 35 years with a mean of 11.7 (± 7.8) years. Approximately, 73% of the nurses demonstrated a low level of knowledge of pressure ulcer identification/staging, 69.4% demonstrated an average level of knowledge of risk factors and 79.9% demonstrated high level of knowledge of preventive practices. The relationship between nurses' knowledge of risk factors and knowledge of preventive practices (p = 0.37) was not significant. Nurses demonstrated a knowledge deficit in core areas on pressure ulcer identification/staging, risk factors' assessment and evidence-based preventive practices. In order to address this dearth, there is a need to institute an educational-based practice-guideline on pressure ulcer prevention for nurses.

Cost effectiveness of nutrition support in the prevention of pressure ulcer in hospitals.

PubMed

Banks, M D; Graves, N; Bauer, J D; Ash, S

2013-01-01

This study estimates the economic outcomes of a nutrition intervention to at-risk patients compared with standard care in the prevention of pressure ulcer. Statistical models were developed to predict 'cases of pressure ulcer avoided', 'number of bed days gained' and 'change to economic costs' in public hospitals in 2002-2003 in Queensland, Australia. Input parameters were specified and appropriate probability distributions fitted for: number of discharges per annum; incidence rate for pressure ulcer; independent effect of pressure ulcer on length of stay; cost of a bed day; change in risk in developing a pressure ulcer associated with nutrition support; annual cost of the provision of a nutrition support intervention for at-risk patients. A total of 1000 random re-samples were made and the results expressed as output probability distributions. The model predicts a mean 2896 (s.d. 632) cases of pressure ulcer avoided; 12, 397 (s.d. 4491) bed days released and corresponding mean economic cost saving of euros 2 869 526 (s.d. 2 078 715) with a nutrition support intervention, compared with standard care. Nutrition intervention is predicted to be a cost-effective approach in the prevention of pressure ulcer in at-risk patients.

Mathematical modelling of cyclic pressure swing adsorption processes

NASA Astrophysics Data System (ADS)

Skvortsov, S. A.; Akulinin, E. I.; Golubyatnikov, O. O.; Dvoretsky, D. S.; Dvoretsky, S. I.

2018-05-01

The paper discusses the results of a numerical analysis of the properties and regimes of the adsorption air separation and oxygen concentration process with a purity of ∼ 40-60%, carried out in a 2-adsorption vacuum-pressure plant with a granular zeolite adsorbent 13X with a productivity of 1.6 · 10-5 m3/s. Computational experiments were carried out using the developed mathematical model and the influence of temperature, pressure, reflux ratio, the duration of the adsorption and desorption stages, the harmonic fluctuations of the inlet pressure during the adsorption stage and the outlet pressure during the desorption stage on the kinetics, and the efficiency of the air separation process by the PSA method were investigated. It is established that the specially organized harmonic fluctuations of the inlet pressure at the stage of adsorption and outlet pressure during the desorption stage lead to an increase in the purity of product oxygen by 4% (vol.).

A novel model of human skin pressure ulcers in mice.

PubMed

Maldonado, Andrés A; Cristóbal, Lara; Martín-López, Javier; Mallén, Mar; García-Honduvilla, Natalio; Buján, Julia

2014-01-01

Pressure ulcers are a prevalent health problem in today's society. The shortage of suitable animal models limits our understanding and our ability to develop new therapies. This study aims to report on the development of a novel and reproducible human skin pressure ulcer model in mice. Male non-obese, diabetic, severe combined immunodeficiency mice (n = 22) were engrafted with human skin. A full-thickness skin graft was placed onto 4×3 cm wounds created on the dorsal skin of the mice. Two groups with permanent grafts were studied after 60 days. The control group (n = 6) was focused on the process of engraftment. Evaluations were conducted with photographic assessment, histological analysis and fluorescence in situ hybridization (FISH) techniques. The pressure ulcer group (n = 12) was created using a compression device. A pressure of 150 mmHg for 8 h, with a total of three cycles of compression-release was exerted. Evaluations were conducted with photographic assessment and histological analysis. Skin grafts in the control group took successfully, as shown by visual assessment, FISH techniques and histological analysis. Pressure ulcers in the second group showed full-thickness skin loss with damage and necrosis of all the epidermal and dermal layers (ulcer stage III) in all cases. Complete repair occurred after 40 days. An inexpensive, reproducible human skin pressure ulcer model has been developed. This novel model will facilitate the development of new clinically relevant therapeutic strategies that can be tested directly on human skin.

A U-shaped Association Between Blood Pressure and Cognitive Impairment in Chinese Elderly.

PubMed

Lv, Yue-Bin; Zhu, Peng-Fei; Yin, Zhao-Xue; Kraus, Virginia Byers; Threapleton, Diane; Chei, Choy-Lye; Brasher, Melanie Sereny; Zhang, Juan; Qian, Han-Zhu; Mao, Chen; Matchar, David Bruce; Luo, Jie-Si; Zeng, Yi; Shi, Xiao-Ming

2017-02-01

Higher or lower blood pressure may relate to cognitive impairment, whereas the relationship between blood pressure and cognitive impairment among the elderly is not well-studied. The study objective was to determine whether blood pressure is associated with cognitive impairment in the elderly, and, if so, to accurately describe the association. Cross-sectional data from the sixth wave of the Chinese Longitudinal Healthy Longevity Survey (CLHLS) conducted in 2011. Community-based setting in longevity areas in China. A total of 7144 Chinese elderly aged 65 years and older were included in the sample. Systolic blood pressures (SBP) and diastolic blood pressures (DBP) were measured, pulse pressure (PP) was calculated as (SBP) - (DBP) and mean arterial pressures (MAP) was calculated as 1/3(SBP) + 2/3(DBP). Cognitive function was assessed via a validated Mini-Mental State Examination (MMSE). Based on the results of generalized additive models (GAMs), U-shaped associations were identified between cognitive impairment and SBP, DBP, PP, and MAP. The cutpoints at which risk for cognitive impairment (MMSE <24) was minimized were determined by quadratic models as 141 mm Hg, 85 mm Hg, 62 mm Hg, and 103 mm Hg, respectively. In the logistic models, U-shaped associations remained for SBP, DBP, and MAP but not PP. Below the identified cutpoints, each 1-mm Hg decrease in blood pressure corresponded to 0.7%, 1.1%, and 1.1% greater risk in the risk of cognitive impairment, respectively. Above the cutpoints, each 1-mm Hg increase in blood pressure corresponded to 1.2%, 1.8%, and 2.1% greater risk of cognitive impairment for SBP, DBP, and MAP, respectively. A U-shaped association between blood pressure and cognitive function in an elderly Chinese population was found. Recognition of these instances is important in identifying the high-risk population for cognitive impairment and to individualize blood pressure management for cognitive impairment prevention. Copyright © 2016

A U-shaped Association between Blood Pressure and Cognitive Impairment in Chinese Elderly

PubMed Central

Lv, Yue-Bin; Zhu, Peng-Fei; Yin, Zhao-Xue; Kraus, Virginia Byers; Threapleton, Diane; Chei, Choy-Lye; Brasher, Melanie Sereny; Zhang, Juan; Qian, Han-Zhu; Mao, Chen; Matchar, David Bruce; Luo, Jie-Si; Zeng, Yi; Shi, Xiao-Ming

2017-01-01

Objectives Higher or lower blood pressure may relate to cognitive impairment, while the relationship between blood pressure and cognitive impairment among the elderly is not well-studied. The study objective was to determine whether blood pressure is associated with cognitive impairment in the elderly, and, if so, to accurately describe the association. Design Cross-sectional data from the sixth wave of the Chinese Longitudinal Healthy Longevity Survey (CLHLS) conducted in 2011 Setting Community-based setting in longevity areas in China Participants 7,144 Chinese elderly aged 65 years and older were included in the sample Measures Systolic blood pressures (SBP) and diastolic blood pressures (DBP) were measured, pulse pressure (PP) was calculated as (SBP)-(DBP) and mean arterial pressures (MAP) was calculated as 1/3(SBP) + 2/3(DBP). Cognitive function was assessed via a validated Mini-Mental State Examination (MMSE). Results Based on the results of generalized additive models (GAMs), U-shaped associations were identified between cognitive impairment and SBP, DBP, PP and MAP. The cut-points at which risk for cognitive impairment (MMSE<24) was minimized were determined by quadratic models as 141 mmHg, 85 mmHg, 62 mmHg and 103 mmHg, respectively. In the logistic models, U-shaped associations remained for SBP, DBP, and MAP but not PP. Below the identified cut-points, each 1mmHg decrease in blood pressure corresponded to 0.7%, 1.1%, and 1.1% greater risk in the risk of cognitive impairment, respectively. Above the cut-points, each 1mmHg increase in blood pressure corresponded to 1.2%, 1.8%, and 2.1% greater risk of cognitive impairment for SBP, DBP and MAP, respectively. Conclusion A U-shaped association between blood pressure and cognitive function in an elderly Chinese population was found. Recognition of these instances is important identifying the high-risk population for cognitive impairment and to individualize blood pressure management for cognitive impairment

Temporal modelling of ballast water discharge and ship-mediated invasion risk to Australia

PubMed Central

Cope, Robert C.; Prowse, Thomas A. A.; Ross, Joshua V.; Wittmann, Talia A.; Cassey, Phillip

2015-01-01

Biological invasions have the potential to cause extensive ecological and economic damage. Maritime trade facilitates biological invasions by transferring species in ballast water, and on ships' hulls. With volumes of maritime trade increasing globally, efforts to prevent these biological invasions are of significant importance. Both the International Maritime Organization and the Australian government have developed policy seeking to reduce the risk of these invasions. In this study, we constructed models for the transfer of ballast water into Australian waters, based on historic ballast survey data. We used these models to hindcast ballast water discharge over all vessels that arrived in Australian waters between 1999 and 2012. We used models for propagule survival to compare the risk of ballast-mediated propagule transport between ecoregions. We found that total annual ballast discharge volume into Australia more than doubled over the study period, with the vast majority of ballast water discharge and propagule pressure associated with bulk carrier traffic. As such, the ecoregions suffering the greatest risk are those associated with the export of mining commodities. As global marine trade continues to increase, effective monitoring and biosecurity policy will remain necessary to combat the risk of future marine invasion events. PMID:26064643

An electronic scanner of pressure for wind tunnel models

NASA Technical Reports Server (NTRS)

Kauffman, Ronald C.; Coe, Charles F.

1986-01-01

An electronic scanner of pressure (ESOP) has been developed by NASA Ames Research Center for installation in wind tunnel models. An ESOP system consists of up to 20 pressure modules (PMs), each with 48 pressure transducers and a heater, an analog-to-digital (A/D) converter module, a microprocessor, a data controller, a monitor unit, a control and processing unit, and a heater controller. The PMs and the A/D converter module are sized to be installed in the models tested in the Ames Aerodynamics Division wind tunnels. A unique feature of the pressure module is the lack of moving parts such as a pneumatic switch used in other systems for in situ calibrations. This paper describes the ESOP system and the results of the initial testing of the system. The initial results indicate the system meets the original design goal of 0.15 percent accuracy.

Computational Analyses of Pressurization in Cryogenic Tanks

NASA Technical Reports Server (NTRS)

Ahuja, Vineet; Hosangadi, Ashvin; Mattick, Stephen; Lee, Chun P.; Field, Robert E.; Ryan, Harry

2008-01-01

A) Advanced Gas/Liquid Framework with Real Fluids Property Routines: I. A multi-fluid formulation in the preconditioned CRUNCH CFD(Registered TradeMark) code developed where a mixture of liquid and gases can be specified: a) Various options for Equation of state specification available (from simplified ideal fluid mixtures, to real fluid EOS such as SRK or BWR models). b) Vaporization of liquids driven by pressure value relative to vapor pressure and combustion of vapors allowed. c) Extensive validation has been undertaken. II. Currently working on developing primary break-up models and surface tension effects for more rigorous phase-change modeling and interfacial dynamics B) Framework Applied to Run-time Tanks at Ground Test Facilities C) Framework Used For J-2 Upper Stage Tank Modeling: 1) NASA MSFC tank pressurization: a) Hydrogen and oxygen tank pre-press, repress and draining being modeled at NASA MSFC. 2) NASA AMES tank safety effort a) liquid hydrogen and oxygen are separated by a baffle in the J-2 tank. We are modeling pressure rise and possible combustion if a hole develops in the baffle and liquid hydrogen leaks into the oxygen tank. Tank pressure rise rates simulated and risk of combustion evaluated.

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.

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.

Intracochlear Scala Media Pressure Measurement: Implications for Models of Cochlear Mechanics

PubMed Central

Kale, Sushrut S.; Olson, Elizabeth S.

2015-01-01

Models of the active cochlea build upon the underlying passive mechanics. Passive cochlear mechanics is based on physical and geometrical properties of the cochlea and the fluid-tissue interaction between the cochlear partition and the surrounding fluid. Although the fluid-tissue interaction between the basilar membrane and the fluid in scala tympani (ST) has been explored in both active and passive cochleae, there was no experimental data on the fluid-tissue interaction on the scala media (SM) side of the partition. To this aim, we measured sound-evoked intracochlear pressure in SM close to the partition using micropressure sensors. All the SM pressure data are from passive cochleae, likely because the SM cochleostomy led to loss of endocochlear potential. Thus, these experiments are studies of passive cochlear mechanics. SM pressure close to the tissue showed a pattern of peaks and notches, which could be explained as an interaction between fast and slow (i.e., traveling wave) pressure modes. In several animals SM and ST pressure were measured in the same cochlea. Similar to previous studies, ST-pressure was dominated by a slow, traveling wave mode at stimulus frequencies in the vicinity of the best frequency of the measurement location, and by a fast mode above best frequency. Antisymmetric pressure between SM and ST supported the classic single-partition cochlear models, or a dual-partition model with tight coupling between partitions. From the SM and ST pressure we calculated slow and fast modes, and from active ST pressure we extrapolated the passive findings to the active case. The passive slow mode estimated from SM and ST data was low-pass in nature, as predicted by cochlear models. PMID:26682824

Understanding the risk factors of trauma center closures: do financial pressure and community characteristics matter?

PubMed

Shen, Yu-Chu; Hsia, Renee Y; Kuzma, Kristen

2009-09-01

We analyze whether hazard rates of shutting down trauma centers are higher due to financial pressures or in areas with vulnerable populations (such as minorities or the poor). This is a retrospective study of all hospitals with trauma center services in urban areas in the continental US between 1990 and 2005, identified from the American Hospital Association Annual Surveys. These data were linked with Medicare cost reports, and supplemented with other sources, including the Area Resource File. We analyze the hazard rates of trauma center closures among several dimensions of risk factors using discrete-time proportional hazard models. The number of trauma center closures increased from 1990 to 2005, with a total of 339 during this period. The hazard rate of closing trauma centers in hospitals with a negative profit margin is 1.38 times higher than those hospitals without the negative profit margin (P < 0.01). Hospitals receiving more generous Medicare reimbursements face a lower hazard of shutting down trauma centers (ratio: 0.58, P < 0.01) than those receiving below average reimbursement. Hospitals in areas with higher health maintenance organizations penetration face a higher hazard of trauma center closure (ratio: 2.06, P < 0.01). Finally, hospitals in areas with higher shares of minorities face a higher risk of trauma center closure (ratio: 1.69, P < 0.01). Medicaid load and uninsured populations, however, are not risk factors for higher rates of closure after we control for other financial and community characteristics. Our findings give an indication on how the current proposals to cut public spending could exacerbate the trauma closure particularly among areas with high shares of minorities. In addition, given the negative effect of health maintenance organizations on trauma center survival, the growth of Medicaid managed care population should be monitored. Finally, high shares of Medicaid or uninsurance by themselves are not independent risk factors for

[Reliability and validity of the Braden Scale for predicting pressure sore risk].

PubMed

Boes, C

2000-12-01

For more accurate and objective pressure sore risk assessment various risk assessment tools were developed mainly in the USA and Great Britain. The Braden Scale for Predicting Pressure Sore Risk is one such example. By means of a literature analysis of German and English texts referring to the Braden Scale the scientific control criteria reliability and validity will be traced and consequences for application of the scale in Germany will be demonstrated. Analysis of 4 reliability studies shows an exclusive focus on interrater reliability. Further, even though examination of 19 validity studies occurs in many different settings, such examination is limited to the criteria sensitivity and specificity (accuracy). The range of sensitivity and specificity level is 35-100%. The recommended cut off points rank in the field of 10 to 19 points. The studies prove to be not comparable with each other. Furthermore, distortions in these studies can be found which affect accuracy of the scale. The results of the here presented analysis show an insufficient proof for reliability and validity in the American studies. In Germany, the Braden scale has not yet been tested under scientific criteria. Such testing is needed before using the scale in different German settings. During the course of such testing, construction and study procedures of the American studies can be used as a basis as can the problems be identified in the analysis presented below.

Blood Pressure Genetic Risk Score Predicts Blood Pressure Responses to Dietary Sodium and Potassium: The GenSalt Study (Genetic Epidemiology Network of Salt Sensitivity).

PubMed

Nierenberg, Jovia L; Li, Changwei; He, Jiang; Gu, Dongfeng; Chen, Jichun; Lu, Xiangfeng; Li, Jianxin; Wu, Xigui; Gu, C Charles; Hixson, James E; Rao, Dabeeru C; Kelly, Tanika N

2017-12-01

We examined the association between genetic risk score (GRS) for blood pressure (BP), based on single nucleotide polymorphisms identified in previous BP genome-wide association study meta-analyses, and salt and potassium sensitivity of BP among participants of the GenSalt study (Genetic Epidemiology Network of Salt Sensitivity). The GenSalt study was conducted among 1906 participants who underwent a 7-day low-sodium (51.3 mmol sodium/d), 7-day high-sodium (307.8 mmol sodium/d), and 7-day high-sodium plus potassium (60 mmol potassium/d) intervention. BP was measured 9× at baseline and at the end of each intervention period using a random zero sphygmomanometer. Associations between systolic BP (SBP), diastolic BP, and mean arterial pressure GRS and respective SBP, diastolic BP, and mean arterial pressure responses to the dietary interventions were assessed using mixed linear regression models that accounted for familial dependencies and adjusted for age, sex, field center, body mass index, and baseline BP. As expected, baseline SBP, diastolic BP, and mean arterial pressure significantly increased per quartile increase in GRS ( P =2.7×10 -8 , 9.8×10 -8 , and 6.4×10 -6 , respectively). In contrast, increasing GRS quartile conferred smaller SBP, diastolic BP, and mean arterial pressure responses to the low-sodium intervention ( P =1.4×10 -3 , 0.02, and 0.06, respectively) and smaller SBP responses to the high-sodium and potassium interventions ( P =0.10 and 0.05). In addition, overall findings were similar when examining GRS as a continuous measure. Contrary to our initial hypothesis, we identified an inverse relationship between BP GRS and salt and potassium sensitivity of BP. These data may provide novel implications on the relationship between BP responses to dietary sodium and potassium and hypertension. © 2017 American Heart Association, Inc.

Low-pressure hydrogen plasmas explored using a global model

NASA Astrophysics Data System (ADS)

Samuell, Cameron M.; Corr, Cormac S.

2016-02-01

Low-pressure hydrogen plasmas have found applications in a variety of technology areas including fusion, neutral beam injection and material processing applications. To better understand these discharges, a global model is developed to predict the behaviour of electrons, ground-state atomic and molecular hydrogen, three positive ion species (H+, \\text{H}2+ , and \\text{H}3+ ), a single negative ion species (H-), and fourteen vibrationally excited states of molecular hydrogen ({{\\text{H}}2}≤ft(\\upsilon =1\\right. -14)). The model is validated by comparison with experimental results from a planar inductively coupled GEC reference cell and subsequently applied to the MAGPIE linear helicon reactor. The MAGPIE reactor is investigated for a range of pressures from 1 to 100 mTorr and powers up to 5 kW. With increasing power between 50 W and 5 kW at 10 mTorr the density of all charged species increases as well as the dissociative fraction while the electron temperature remains almost constant at around 3 eV. For gas pressures from 1-100 mTorr at an input power of 1 kW, the electron density remains almost constant, the electron temperature and dissociative fraction decreases, while \\text{H}3+ density increases in density and also dominates amongst ion species. Across these power and pressure scans, electronegativity remains approximately constant at around 2.5%. The power and pressure determines the dominant ion species in the plasma with \\text{H}3+ observed to dominate at high pressures and low powers whereas H+ tends to be dominant at low pressures and high powers. A sensitivity analysis is used to demonstrate how experimental parameters (power, pressure, reactor wall material, geometry etc) influence individual species’ density as well as the electron temperature. Physical reactor changes including the length, radius and wall recombination coefficient are found to have the largest influence on outputs obtained from the model.

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.

Plantar pressure asymmetry and risk of stress injuries in the foot of young soccer players.

PubMed

Azevedo, Renato R; da Rocha, Emmanuel S; Franco, Pedro S; Carpes, Felipe P

2017-03-01

Asymmetries in the magnitude of plantar pressure are considered a risk factor for stress fracture of the fifth metatarsal in soccer athletes. To investigate the presence of plantar pressure asymmetries among young soccer athletes. Observational. Laboratory. Thirty young adolescents divided into a soccer player group (n = 15) or a matched control group (n = 15). Mean plantar pressure was determined for seven different regions of the foot. Data were compared between the preferred and non-preferred foot, and between the groups, during barefoot standing on a pressure mat system. Higher pressure was found in the hallux, 5th metatarsal and medial rearfoot of the non-preferred foot in the young soccer players. These asymmetries were not observed in the control group. Magnitudes of plantar pressure did not differ between the groups. Young soccer players present asymmetries in plantar pressure in the hallux, 5th metatarsal and medial rearfoot, with higher pressure observed in the non-preferred foot. Copyright © 2016 Elsevier Ltd. All rights reserved.

Prediction of high airway pressure using a non-linear autoregressive model of pulmonary mechanics.

PubMed

Langdon, Ruby; Docherty, Paul D; Schranz, Christoph; Chase, J Geoffrey

2017-11-02

For mechanically ventilated patients with acute respiratory distress syndrome (ARDS), suboptimal PEEP levels can cause ventilator induced lung injury (VILI). In particular, high PEEP and high peak inspiratory pressures (PIP) can cause over distension of alveoli that is associated with VILI. However, PEEP must also be sufficient to maintain recruitment in ARDS lungs. A lung model that accurately and precisely predicts the outcome of an increase in PEEP may allow dangerous high PIP to be avoided, and reduce the incidence of VILI. Sixteen pressure-flow data sets were collected from nine mechanically ventilated ARDs patients that underwent one or more recruitment manoeuvres. A nonlinear autoregressive (NARX) model was identified on one or more adjacent PEEP steps, and extrapolated to predict PIP at 2, 4, and 6 cmH 2 O PEEP horizons. The analysis considered whether the predicted and measured PIP exceeded a threshold of 40 cmH 2 O. A direct comparison of the method was made using the first order model of pulmonary mechanics (FOM(I)). Additionally, a further, more clinically appropriate method for the FOM was tested, in which the FOM was trained on a single PEEP prior to prediction (FOM(II)). The NARX model exhibited very high sensitivity (> 0.96) in all cases, and a high specificity (> 0.88). While both FOM methods had a high specificity (> 0.96), the sensitivity was much lower, with a mean of 0.68 for FOM(I), and 0.82 for FOM(II). Clinically, false negatives are more harmful than false positives, as a high PIP may result in distension and VILI. Thus, the NARX model may be more effective than the FOM in allowing clinicians to reduce the risk of applying a PEEP that results in dangerously high airway pressures.

Advantages of new cardiovascular risk-assessment strategies in high-risk patients with hypertension.

PubMed

Ruilope, Luis M; Segura, Julian

2005-10-01

Accurate assessment of cardiovascular disease (CVD) risk in patients with hypertension is important when planning appropriate treatment of modifiable risk factors. The causes of CVD are multifactorial, and hypertension seldom exists as an isolated risk factor. Classic models of risk assessment are more accurate than a simple counting of risk factors, but they are not generalizable to all populations. In addition, the risk associated with hypertension is graded, continuous, and independent of other risk factors, and this is not reflected in classic models of risk assessment. This article is intended to review both classic and newer models of CVD risk assessment. MEDLINE was searched for articles published between 1990 and 2005 that contained the terms cardiovascular disease, hypertension, or risk assessment. Articles describing major clinical trials, new data about cardiovascular risk, or global risk stratification were selected for review. Some patients at high long-term risk for CVD events (eg, patients aged <50 years with multiple risk factors) may go untreated because they do not meet the absolute risk-intervention threshold of 20% risk over 10 years with the classic model. Recognition of the limitations of classic risk-assessment models led to new guidelines, particularly those of the European Society of Hypertension-European Society of Cardiology. These guidelines view hypertension as one of many risk and disease factors that require treatment to decrease risk. These newer guidelines include a more comprehensive range of risk factors and more finely graded blood pressure ranges to stratify patients by degree of risk. Whether they accurately predict CVD risk in most populations is not known. Evidence from the Valsartan Antihypertensive Long-term Use Evaluation (VALUE) study, which stratified patients by several risk and disease factors, highlights the predictive value of some newer CVD risk assessments. Modern risk assessments, which include blood pressure

Office blood pressure or ambulatory blood pressure for the prediction of cardiovascular events.

PubMed

Mortensen, Rikke Nørmark; Gerds, Thomas Alexander; Jeppesen, Jørgen Lykke; Torp-Pedersen, Christian

2017-11-21

To determine the added value of (i) 24-h ambulatory blood pressure relative to office blood pressure and (ii) night-time ambulatory blood pressure relative to daytime ambulatory blood pressure for 10-year person-specific absolute risks of fatal and non-fatal cardiovascular events. A total of 7927 participants were included from the International Database on Ambulatory blood pressure monitoring in relation to Cardiovascular Outcomes. We used cause-specific Cox regression to predict 10-year person-specific absolute risks of fatal and non-fatal cardiovascular events. Discrimination of 10-year outcomes was assessed by time-dependent area under the receiver operating characteristic curve (AUC). No differences in predicted risks were observed when comparing office blood pressure and ambulatory blood pressure. The median difference in 10-year risks (1st; 3rd quartile) was -0.01% (-0.3%; 0.1%) for cardiovascular mortality and -0.1% (-1.1%; 0.5%) for cardiovascular events. The difference in AUC (95% confidence interval) was 0.65% (0.22-1.08%) for cardiovascular mortality and 1.33% (0.83-1.84%) for cardiovascular events. Comparing daytime and night-time blood pressure, the median difference in 10-year risks was 0.002% (-0.1%; 0.1%) for cardiovascular mortality and -0.01% (-0.5%; 0.2%) for cardiovascular events. The difference in AUC was 0.10% (-0.08 to 0.29%) for cardiovascular mortality and 0.15% (-0.06 to 0.35%) for cardiovascular events. Ten-year predictions obtained from ambulatory blood pressure are similar to predictions from office blood pressure. Night-time blood pressure does not improve 10-year predictions obtained from daytime measurements. For an otherwise healthy population sufficient prognostic accuracy of cardiovascular risks can be achieved with office blood pressure. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2017. For permissions, please email: journals.permissions@oup.com.

Peripheral Edema, Central Venous Pressure, and Risk of AKI in Critical Illness

PubMed Central

Chen, Kenneth P.; Cavender, Susan; Lee, Joon; Feng, Mengling; Mark, Roger G.; Celi, Leo Anthony; Mukamal, Kenneth J.

2016-01-01

Background and objectives Although venous congestion has been linked to renal dysfunction in heart failure, its significance in a broader context has not been investigated. Design, setting, participants, & measurements Using an inception cohort of 12,778 critically ill adult patients admitted to an urban tertiary medical center between 2001 and 2008, we examined whether the presence of peripheral edema on admission physical examination was associated with an increased risk of AKI within the first 7 days of critical illness. In addition, in those with admission central venous pressure (CVP) measurements, we examined the association of CVPs with subsequent AKI. AKI was defined using the Kidney Disease Improving Global Outcomes criteria. Results Of the 18% (n=2338) of patients with peripheral edema on admission, 27% (n=631) developed AKI, compared with 16% (n=1713) of those without peripheral edema. In a model that included adjustment for comorbidities, severity of illness, and the presence of pulmonary edema, peripheral edema was associated with a 30% higher risk of AKI (95% confidence interval [95% CI], 1.15 to 1.46; P<0.001), whereas pulmonary edema was not significantly related to risk. Peripheral edema was also associated with a 13% higher adjusted risk of a higher AKI stage (95% CI, 1.07 to 1.20; P<0.001). Furthermore, levels of trace, 1+, 2+, and 3+ edema were associated with 34% (95% CI, 1.10 to 1.65), 17% (95% CI, 0.96 to 1.14), 47% (95% CI, 1.18 to 1.83), and 57% (95% CI, 1.07 to 2.31) higher adjusted risk of AKI, respectively, compared with edema-free patients. In the 4761 patients with admission CVP measurements, each 1 cm H2O higher CVP was associated with a 2% higher adjusted risk of AKI (95% CI, 1.00 to 1.03; P=0.02). Conclusions Venous congestion, as manifested as either peripheral edema or increased CVP, is directly associated with AKI in critically ill patients. Whether treatment of venous congestion with diuretics can modify this risk will require

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

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.

Modeling and simulation of pressure waves generated by nano-thermite reactions

NASA Astrophysics Data System (ADS)

Martirosyan, Karen S.; Zyskin, Maxim; Jenkins, Charles M.; (Yuki) Horie, Yasuyuki

2012-11-01

This paper reports the modeling of pressure waves from the explosive reaction of nano-thermites consisting of mixtures of nanosized aluminum and oxidizer granules. Such nanostructured thermites have higher energy density (up to 26 kJ/cm3) and can generate a transient pressure pulse four times larger than that from trinitrotoluene (TNT) based on volume equivalence. A plausible explanation for the high pressure generation is that the reaction times are much shorter than the time for a shock wave to propagate away from the reagents region so that all the reaction energy is dumped into the gaseous products almost instantaneously and thereby a strong shock wave is generated. The goal of the modeling is to characterize the gas dynamic behavior for thermite reactions in a cylindrical reaction chamber and to model the experimentally measured pressure histories. To simplify the details of the initial stage of the explosive reaction, it is assumed that the reaction generates a one dimensional shock wave into an air-filled cylinder and propagates down the tube in a self-similar mode. Experimental data for Al/Bi2O3 mixtures were used to validate the model with attention focused on the ratio of specific heats and the drag coefficient. Model predictions are in good agreement with the measured pressure histories.

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

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.

Limitations of demand- and pressure-driven modeling for large deficient networks

NASA Astrophysics Data System (ADS)

Braun, Mathias; Piller, Olivier; Deuerlein, Jochen; Mortazavi, Iraj

2017-10-01

The calculation of hydraulic state variables for a network is an important task in managing the distribution of potable water. Over the years the mathematical modeling process has been improved by numerous researchers for utilization in new computer applications and the more realistic modeling of water distribution networks. But, in spite of these continuous advances, there are still a number of physical phenomena that may not be tackled correctly by current models. This paper will take a closer look at the two modeling paradigms given by demand- and pressure-driven modeling. The basic equations are introduced and parallels are drawn with the optimization formulations from electrical engineering. These formulations guarantee the existence and uniqueness of the solution. One of the central questions of the French and German research project ResiWater is the investigation of the network resilience in the case of extreme events or disasters. Under such extraordinary conditions where models are pushed beyond their limits, we talk about deficient network models. Examples of deficient networks are given by highly regulated flow, leakage or pipe bursts and cases where pressure falls below the vapor pressure of water. These examples will be presented and analyzed on the solvability and physical correctness of the solution with respect to demand- and pressure-driven models.

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.

High-flow oxygen therapy: pressure analysis in a pediatric airway model.

PubMed

Urbano, Javier; del Castillo, Jimena; López-Herce, Jesús; Gallardo, José A; Solana, María J; Carrillo, Ángel

2012-05-01

The mechanism of high-flow oxygen therapy and the pressures reached in the airway have not been defined. We hypothesized that the flow would generate a low continuous positive pressure, and that elevated flow rates in this model could produce moderate pressures. The objective of this study was to analyze the pressure generated by a high-flow oxygen therapy system in an experimental model of the pediatric airway. An experimental in vitro study was performed. A high-flow oxygen therapy system was connected to 3 types of interface (nasal cannulae, nasal mask, and oronasal mask) and applied to 2 types of pediatric manikin (infant and neonatal). The pressures generated in the circuit, in the airway, and in the pharynx were measured at different flow rates (5, 10, 15, and 20 L/min). The experiment was conducted with and without a leak (mouth sealed and unsealed). Linear regression analyses were performed for each set of measurements. The pressures generated with the different interfaces were very similar. The maximum pressure recorded was 4 cm H(2)O with a flow of 20 L/min via nasal cannulae or nasal mask. When the mouth of the manikin was held open, the pressures reached in the airway and pharynxes were undetectable. Linear regression analyses showed a similar linear relationship between flow and pressures measured in the pharynx (pressure = -0.375 + 0.138 × flow) and in the airway (pressure = -0.375 + 0.158 × flow) with the closed mouth condition. According to our hypothesis, high-flow oxygen therapy systems produced a low-level CPAP in an experimental pediatric model, even with the use of very high flow rates. Linear regression analyses showed similar linear relationships between flow and pressures measured in the pharynx and in the airway. This finding suggests that, at least in part, the effects may be due to other mechanisms.

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.

Intracochlear Scala Media Pressure Measurement: Implications for Models of Cochlear Mechanics.

PubMed

Kale, Sushrut S; Olson, Elizabeth S

2015-12-15

Models of the active cochlea build upon the underlying passive mechanics. Passive cochlear mechanics is based on physical and geometrical properties of the cochlea and the fluid-tissue interaction between the cochlear partition and the surrounding fluid. Although the fluid-tissue interaction between the basilar membrane and the fluid in scala tympani (ST) has been explored in both active and passive cochleae, there was no experimental data on the fluid-tissue interaction on the scala media (SM) side of the partition. To this aim, we measured sound-evoked intracochlear pressure in SM close to the partition using micropressure sensors. All the SM pressure data are from passive cochleae, likely because the SM cochleostomy led to loss of endocochlear potential. Thus, these experiments are studies of passive cochlear mechanics. SM pressure close to the tissue showed a pattern of peaks and notches, which could be explained as an interaction between fast and slow (i.e., traveling wave) pressure modes. In several animals SM and ST pressure were measured in the same cochlea. Similar to previous studies, ST-pressure was dominated by a slow, traveling wave mode at stimulus frequencies in the vicinity of the best frequency of the measurement location, and by a fast mode above best frequency. Antisymmetric pressure between SM and ST supported the classic single-partition cochlear models, or a dual-partition model with tight coupling between partitions. From the SM and ST pressure we calculated slow and fast modes, and from active ST pressure we extrapolated the passive findings to the active case. The passive slow mode estimated from SM and ST data was low-pass in nature, as predicted by cochlear models. Copyright © 2015 Biophysical Society. Published by Elsevier Inc. All rights reserved.

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

Using risk-adjustment models to identify high-cost risks.

PubMed

Meenan, Richard T; Goodman, Michael J; Fishman, Paul A; Hornbrook, Mark C; O'Keeffe-Rosetti, Maureen C; Bachman, Donald J

2003-11-01

We examine the ability of various publicly available risk models to identify high-cost individuals and enrollee groups using multi-HMO administrative data. Five risk-adjustment models (the Global Risk-Adjustment Model [GRAM], Diagnostic Cost Groups [DCGs], Adjusted Clinical Groups [ACGs], RxRisk, and Prior-expense) were estimated on a multi-HMO administrative data set of 1.5 million individual-level observations for 1995-1996. Models produced distributions of individual-level annual expense forecasts for comparison to actual values. Prespecified "high-cost" thresholds were set within each distribution. The area under the receiver operating characteristic curve (AUC) for "high-cost" prevalences of 1% and 0.5% was calculated, as was the proportion of "high-cost" dollars correctly identified. Results are based on a separate 106,000-observation validation dataset. For "high-cost" prevalence targets of 1% and 0.5%, ACGs, DCGs, GRAM, and Prior-expense are very comparable in overall discrimination (AUCs, 0.83-0.86). Given a 0.5% prevalence target and a 0.5% prediction threshold, DCGs, GRAM, and Prior-expense captured $963,000 (approximately 3%) more "high-cost" sample dollars than other models. DCGs captured the most "high-cost" dollars among enrollees with asthma, diabetes, and depression; predictive performance among demographic groups (Medicaid members, members over 64, and children under 13) varied across models. Risk models can efficiently identify enrollees who are likely to generate future high costs and who could benefit from case management. The dollar value of improved prediction performance of the most accurate risk models should be meaningful to decision-makers and encourage their broader use for identifying high costs.

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

... criteria as an alternative to the pressure testing in § 195.302(b)(1)(i)-(iii) and § 195.302(b)(2)(i) of... in paragraph (b) of this section as follows: (1) Risk Classification A if the location indicator is ranked as low or medium risk, the product and volume indicators are ranked as low risk, and the...

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

... criteria as an alternative to the pressure testing in § 195.302(b)(1)(i)-(iii) and § 195.302(b)(2)(i) of... in paragraph (b) of this section as follows: (1) Risk Classification A if the location indicator is ranked as low or medium risk, the product and volume indicators are ranked as low risk, and the...

Reusability of EMR Data for Applying Cubbin and Jackson Pressure Ulcer Risk Assessment Scale in Critical Care Patients

PubMed Central

Kim, Eunkyung; Lee, JuHee; Kim, Young Ah

2013-01-01

Objectives The purposes of this study were to examine the predictive validity of the Cubbin and Jackson pressure ulcer risk assessment scale for the development of pressure ulcers in intensive care unit (ICU) patients retrospectively and to evaluate the reusability of Electronic Medical Records (EMR) data. Methods A retrospective design was used to examine 829 cases admitted to four ICUs in a tertiary care hospital from May 2010 to April 2011. Patients who were without pressure ulcers at admission to ICU, 18 years or older, and had stayed in ICU for 24 hours or longer were included. Sensitivity, specificity, positive predictive value, negative predictive value, and area under the curve (AUC) were calculated. Results The reported incidence rate of pressure ulcers among the study subjects was 14.2%. At the cut-off score of 24 of the Cubbin and Jackson scale, the sensitivity, specificity, positive predictive value, negative predictive value, and AUC were 72.0%, 68.8%, 27.7%, 93.7%, and 0.76, respectively. Eight items out 10 of the Cubbin and Jackson scale were readily available in the EMR data. Conclusions The Cubbin and Jackson scale performed slightly better than the Braden scale to predict pressure ulcer development. Eight items of the Cubbin and Jackson scale except mobility and hygiene can be extracted from the EMR, which initially demonstrated the reusability of EMR data for pressure ulcer risk assessment. If the Cubbin and Jackson scale is a part of the EMR assessment form, it would help nurses perform tasks to effectively prevent pressure ulcers with an EMR alert for high-risk patients. PMID:24523990

Iranian risk model as a predictive tool for retinopathy in patients with type 2 diabetes.

PubMed

Azizi-Soleiman, Fatemeh; Heidari-Beni, Motahar; Ambler, Gareth; Omar, Rumana; Amini, Masoud; Hosseini, Sayed-Mohsen

2015-10-01

Diabetic retinopathy (DR) is the leading cause of blindness in patients with type 1 or type 2 diabetes. The gold standard for the detection of DR requires expensive equipment. This study was undertaken to develop a simple and practical scoring system to predict the probability of DR. A total of 1782 patients who had first-degree relatives with type II diabetes were selected. Eye examinations were performed by an expert ophthalmologist. Biochemical and anthropometric predictors of DR were measured. Logistic regression was used to develop a statistical model that can be used to predict DR. Goodness of fit was examined using the Hosmer-Lemeshow test and the area under the receiver operating characteristic (ROC) curve. The risk model demonstrated good calibration and discrimination (ROC area=0.76) in the validation sample. Factors associated with DR in our model were duration of diabetes (odds ratio [OR]=2.14, confidence interval [CI] 95%=1.87 to 2.45); glycated hemoglobin (A1C) (OR=1.21, CI 95%=1.13 to 1.30); fasting plasma glucose (OR=1.83, CI 95%=1.28 to 2.62); systolic blood pressure (OR=1.01, CI 95%= 1.00 to 1.02); and proteinuria (OR=1.37, CI 95%=1.01 to 1.85). The only factor that had a protective effect against DR were body mass index and education level (OR=0.95, CI 95%=0.92 to 0.98). The good performance of our risk model suggests that it may be a useful risk-prediction tool for DR. It consisted of the positive predictors like A1C, diabetes duration, sex (male), fasting plasma glucose, systolic blood pressure and proteinuria, as well as negative risk factors like body mass index and education level. Copyright © 2015 Canadian Diabetes Association. Published by Elsevier Inc. All rights reserved.

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.

Reducing stroke in women with risk factor management: blood pressure and cholesterol.

PubMed

Baghshomali, Sanam; Bushnell, Cheryl

2014-09-01

Stroke is a major cause of death and disability in adults worldwide. Prevention focused on modifiable risk factors, such as hypertension and hyperlipidemia, has shown them to be of significant importance in decreasing the risk of stroke. Multiple studies have brought to light the differences between men and women with regards to stroke and these risk factors. Women have a higher prevalence of stroke, mortality and disability and it has been shown that preventive and treatment options are not as comprehensive for women. Hence, it is of great necessity to evaluate and summarize the differences in gender and stroke risk factors in order to target disparities and optimize prevention, especially because women have a higher lifetime risk of stroke. The purpose of this review is to summarize sex differences in the prevalence of hypertension and hyperlipidemia. In addition, we will review the sex differences in stroke prevention effectiveness and adherence to blood pressure and cholesterol medications, and suggest future directions for research to reduce the burden of stroke in women.

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.

Evaluation of Different Dose-Response Models for High Hydrostatic Pressure Inactivation of Microorganisms

PubMed Central

2017-01-01

Modeling of microbial inactivation by high hydrostatic pressure (HHP) requires a plot of the log microbial count or survival ratio versus time data under a constant pressure and temperature. However, at low pressure and temperature values, very long holding times are needed to obtain measurable inactivation. Since the time has a significant effect on the cost of HHP processing it may be reasonable to fix the time at an appropriate value and quantify the inactivation with respect to pressure. Such a plot is called dose-response curve and it may be more beneficial than the traditional inactivation modeling since short holding times with different pressure values can be selected and used for the modeling of HHP inactivation. For this purpose, 49 dose-response curves (with at least 4 log10 reduction and ≥5 data points including the atmospheric pressure value (P = 0.1 MPa), and with holding time ≤10 min) for HHP inactivation of microorganisms obtained from published studies were fitted with four different models, namely the Discrete model, Shoulder model, Fermi equation, and Weibull model, and the pressure value needed for 5 log10 (P5) inactivation was calculated for all the models above. The Shoulder model and Fermi equation produced exactly the same parameter and P5 values, while the Discrete model produced similar or sometimes the exact same parameter values as the Fermi equation. The Weibull model produced the worst fit (had the lowest adjusted determination coefficient (R2adj) and highest mean square error (MSE) values), while the Fermi equation had the best fit (the highest R2adj and lowest MSE values). Parameters of the models and also P5 values of each model can be useful for the further experimental design of HHP processing and also for the comparison of the pressure resistance of different microorganisms. Further experiments can be done to verify the P5 values at given conditions. The procedure given in this study can also be extended for enzyme

Significant interarm blood pressure difference predicts cardiovascular risk in hypertensive patients: CoCoNet study.

PubMed

Kim, Su-A; Kim, Jang Young; Park, Jeong Bae

2016-06-01

There has been a rising interest in interarm blood pressure difference (IAD), due to its relationship with peripheral arterial disease and its possible relationship with cardiovascular disease. This study aimed to characterize hypertensive patients with a significant IAD in relation to cardiovascular risk. A total of 3699 patients (mean age, 61 ± 11 years) were prospectively enrolled in the study. Blood pressure (BP) was measured simultaneously in both arms 3 times using an automated cuff-oscillometric device. IAD was defined as the absolute difference in averaged BPs between the left and right arm, and an IAD ≥ 10 mm Hg was considered to be significant. The Framingham risk score was used to calculate the 10-year cardiovascular risk. The mean systolic IAD (sIAD) was 4.3 ± 4.1 mm Hg, and 285 (7.7%) patients showed significant sIAD. Patients with significant sIAD showed larger body mass index (P < 0.001), greater systolic BP (P = 0.050), more coronary artery disease (relative risk = 1.356, P = 0.034), and more cerebrovascular disease (relative risk = 1.521, P = 0.072). The mean 10-year cardiovascular risk was 9.3 ± 7.7%. By multiple regression, sIAD was significantly but weakly correlated with the 10-year cardiovascular risk (β = 0.135, P = 0.008). Patients with significant sIAD showed a higher prevalence of coronary artery disease, as well as an increase in 10-year cardiovascular risk. Therefore, accurate measurements of sIAD may serve as a simple and cost-effective tool for predicting cardiovascular risk in clinical settings.

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.

Part 1: Pressure ulcer assessment - the development of Critical Care Pressure Ulcer Assessment Tool made Easy (CALCULATE).

PubMed

Richardson, Annette; Barrow, Isabel

2015-11-01

Critically ill patients are at high risk of developing pressure ulcers resulting in serious untoward patient and health care system outcomes. Pressure ulcer prevention is therefore an important patient safety priority and establishing a structured approach to pressure ulcer risk assessment to identify patients at risk is a critical first step. The literature was searched using three electronic databases from 2000 to 2011 to identify papers reporting on pressure ulcer risk factors and assessment in adult critical care. The review and appraisal of papers were conducted by two critical care nurses. Papers underwent detailed review if they met inclusion criteria where they identified pressure ulcer assessment scores, scales or risk factors and related to adult critical care patients Seven papers were reviewed. No single assessment tool was sufficiently validated for critically ill patients and seven key critical care risk factors were identified. These risk factors were: mechanical ventilation, impaired circulation, dialysis, long surgery, low protein and too unstable to turn. The tool Critical Care Pressure Ulcer Assessment Tool made Easy (CALCULATE) was developed utilizing the risk factors from the literature and expert critical care nursing consensus decision-making. In the absence of current consensus, valid assessment scales and limited evidence for the most appropriate pressure ulcer assessment for critically ill patients, this assessment tool offers an easy, appropriate alternative for critically ill patients than existing tools primarily validated for acute care wards. 'CALCULATE' offers an important contribution towards the advancement and development of critical care pressure ulcer risk assessment. Future research is needed to further enhance and inform pressure ulcer risk assessment of the critically ill patients. The identification of critical care risk factors may be an indicative method of assessing pressure ulcer risk in the critically ill patients. �

[Application of three risk assessment models in occupational health risk assessment of dimethylformamide].

PubMed

Wu, Z J; Xu, B; Jiang, H; Zheng, M; Zhang, M; Zhao, W J; Cheng, J

2016-08-20

Objective: To investigate the application of United States Environmental Protection Agency (EPA) inhalation risk assessment model, Singapore semi-quantitative risk assessment model, and occupational hazards risk assessment index method in occupational health risk in enterprises using dimethylformamide (DMF) in a certain area in Jiangsu, China, and to put forward related risk control measures. Methods: The industries involving DMF exposure in Jiangsu province were chosen as the evaluation objects in 2013 and three risk assessment models were used in the evaluation. EPA inhalation risk assessment model: HQ=EC/RfC; Singapore semi-quantitative risk assessment model: Risk= (HR×ER) 1/2 ; Occupational hazards risk assessment index=2 Health effect level ×2 exposure ratio ×Operation condition level. Results: The results of hazard quotient (HQ>1) from EPA inhalation risk assessment model suggested that all the workshops (dry method, wet method and printing) and work positions (pasting, burdening, unreeling, rolling, assisting) were high risk. The results of Singapore semi-quantitative risk assessment model indicated that the workshop risk level of dry method, wet method and printing were 3.5 (high) , 3.5 (high) and 2.8 (general) , and position risk level of pasting, burdening, unreeling, rolling, assisting were 4 (high) , 4 (high) , 2.8 (general) , 2.8 (general) and 2.8 (general) . The results of occupational hazards risk assessment index method demonstrated that the position risk index of pasting, burdening, unreeling, rolling, assisting were 42 (high) , 33 (high) , 23 (middle) , 21 (middle) and 22 (middle) . The results of Singapore semi-quantitative risk assessment model and occupational hazards risk assessment index method were similar, while EPA inhalation risk assessment model indicated all the workshops and positions were high risk. Conclusion: The occupational hazards risk assessment index method fully considers health effects, exposure, and operating conditions

Available pressure amplitude of linear compressor based on phasor triangle model

NASA Astrophysics Data System (ADS)

Duan, C. X.; Jiang, X.; Zhi, X. Q.; You, X. K.; Qiu, L. M.

2017-12-01

The linear compressor for cryocoolers possess the advantages of long-life operation, high efficiency, low vibration and compact structure. It is significant to study the match mechanisms between the compressor and the cold finger, which determines the working efficiency of the cryocooler. However, the output characteristics of linear compressor are complicated since it is affected by many interacting parameters. The existing matching methods are simplified and mainly focus on the compressor efficiency and output acoustic power, while neglecting the important output parameter of pressure amplitude. In this study, a phasor triangle model basing on analyzing the forces of the piston is proposed. It can be used to predict not only the output acoustic power, the efficiency, but also the pressure amplitude of the linear compressor. Calculated results agree well with the measurement results of the experiment. By this phasor triangle model, the theoretical maximum output pressure amplitude of the linear compressor can be calculated simply based on a known charging pressure and operating frequency. Compared with the mechanical and electrical model of the linear compressor, the new model can provide an intuitionistic understanding on the match mechanism with faster computational process. The model can also explain the experimental phenomenon of the proportional relationship between the output pressure amplitude and the piston displacement in experiments. By further model analysis, such phenomenon is confirmed as an expression of the unmatched design of the compressor. The phasor triangle model may provide an alternative method for the compressor design and matching with the cold finger.

Reducing risk of pressure sores: effects of watch prompts and alarm avoidance on wheelchair push-ups.

PubMed Central

White, G W; Mathews, R M; Fawcett, S B

1989-01-01

People who use wheelchairs are at risk for developing pressure sores. Regular pressure relief, in the form of a wheelchair push-up, is one way to reduce the likelihood of pressure sores. We examined the effects of antecedent (i.e., instructions, audible prompts) and consequent (i.e., alarm avoidance) events on wheelchair push-ups, using a multiple baseline analysis with 2 participants with spina bifida. Results suggest that the combined procedure was more effective than either antecedent or consequent events alone, and there is some evidence suggesting maintenance of effects over time. PMID:2793635

Home-Based Risk of Falling Assessment Test Using a Closed-Loop Balance Model.

PubMed

Ayena, Johannes C; Zaibi, Helmi; Otis, Martin J-D; Menelas, Bob-Antoine J

2016-12-01

The aim of this study is to improve and facilitate the methods used to assess risk of falling at home among older people through the computation of a risk of falling in real time in daily activities. In order to increase a real time computation of the risk of falling, a closed-loop balance model is proposed and compared with One-Leg Standing Test (OLST). This balance model allows studying the postural response of a person having an unpredictable perturbation. Twenty-nine volunteers participated in this study for evaluating the effectiveness of the proposed system which includes seventeen elder participants: ten healthy elderly ( 68.4 ±5.5 years), seven Parkinson's disease (PD) subjects ( 66.28 ±8.9 years), and twelve healthy young adults ( 28.27 ±3.74 years). Our work suggests that there is a relationship between OLST score and the risk of falling based on center of pressure measurement with four low cost force sensors located inside an instrumented insole, which could be predicted using our suggested closed-loop balance model. For long term monitoring at home, this system could be included in a medical electronic record and could be useful as a diagnostic aid tool.

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.

Study on Calculation Model of Culvert Soil Pressure

NASA Astrophysics Data System (ADS)

Liu, Jing; Tian, Xiao-yan; Gao, Xiao-mei

2017-09-01

Culvert diseases are prevalent in highway engineering. There are many factors involved in the occurrence of the disease, and the problem is complex. However, the design cannot accurately determine the role of the soil pressure on the culvert is the main reason to the disease. Based on the theoretical analysis and field test, this paper studies the characteristics of the stress and deformation of the culvert-soil structure. According to the theory of soil mechanics, the calculation model of vertical soil pressure at the top of culvert is determined, and the formula of vertical soil pressure at the top of culvert is deduced. Through the field test of the vertical soil pressure at the top of culvert of several engineering examples, the calculation formula of this paper is verified, which can provide reference for future practical engineering.

Conceptualizing a Dynamic Fall Risk Model Including Intrinsic Risks and Exposures.

PubMed

Klenk, Jochen; Becker, Clemens; Palumbo, Pierpaolo; Schwickert, Lars; Rapp, Kilan; Helbostad, Jorunn L; Todd, Chris; Lord, Stephen R; Kerse, Ngaire

2017-11-01

Falls are a major cause of injury and disability in older people, leading to serious health and social consequences including fractures, poor quality of life, loss of independence, and institutionalization. To design and provide adequate prevention measures, accurate understanding and identification of person's individual fall risk is important. However, to date, the performance of fall risk models is weak compared with models estimating, for example, cardiovascular risk. This deficiency may result from 2 factors. First, current models consider risk factors to be stable for each person and not change over time, an assumption that does not reflect real-life experience. Second, current models do not consider the interplay of individual exposure including type of activity (eg, walking, undertaking transfers) and environmental risks (eg, lighting, floor conditions) in which activity is performed. Therefore, we posit a dynamic fall risk model consisting of intrinsic risk factors that vary over time and exposure (activity in context). eHealth sensor technology (eg, smartphones) begins to enable the continuous measurement of both the above factors. We illustrate our model with examples of real-world falls from the FARSEEING database. This dynamic framework for fall risk adds important aspects that may improve understanding of fall mechanisms, fall risk models, and the development of fall prevention interventions. Copyright © 2017 AMDA – The Society for Post-Acute and Long-Term Care Medicine. Published by Elsevier Inc. All rights reserved.

Impact of risk factors on cardiovascular risk: a perspective on risk estimation in a Swiss population.

PubMed

Chrubasik, Sigrun A; Chrubasik, Cosima A; Piper, Jörg; Schulte-Moenting, Juergen; Erne, Paul

2015-01-01

In models and scores for estimating cardiovascular risk (CVR), the relative weightings given to blood pressure measurements (BPMs), and biometric and laboratory variables are such that even large differences in blood pressure lead to rather low differences in the resulting total risk when compared with other concurrent risk factors. We evaluated this phenomenon based on the PROCAM score, using BPMs made by volunteer subjects at home (HBPMs) and automated ambulatory BPMs (ABPMs) carried out in the same subjects. A total of 153 volunteers provided the data needed to estimate their CVR by means of the PROCAM formula. Differences (deltaCVR) between the risk estimated by entering the ABPM and that estimated with the HBPM were compared with the differences (deltaBPM) between the ABPM and the corresponding HBPM. In addition to the median values (= second quartile), the first and third quartiles of blood pressure profiles were also considered. PROCAM risk values were converted to European Society of Cardiology (ESC) risk values and all participants were assigned to the risk groups low, medium and high. Based on the PROCAM score, 132 participants had a low risk for suffering myocardial infarction, 16 a medium risk and 5 a high risk. The calculated ESC scores classified 125 participants into the low-risk group, 26 into the medium- and 2 into the high-risk group for death from a cardiovascular event. Mean ABPM tended to be higher than mean HBPM. Use of mean systolic ABPM or HBPM in the PROCAM formula had no major impact on the risk level. Our observations are in agreement with the rather low weighting of blood pressure as risk determinant in the PROCAM score. BPMs assessed with different methods had relatively little impact on estimation of cardiovascular risk in the given context of other important determinants. The risk calculations in our unselected population reflect the given classification of Switzerland as a so-called cardiovascular "low risk country".

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.

Scoring life insurance applicants' laboratory results, blood pressure and build to predict all-cause mortality risk.

PubMed

Fulks, Michael; Stout, Robert L; Dolan, Vera F

2012-01-01

Evaluate the degree of medium to longer term mortality prediction possible from a scoring system covering all laboratory testing used for life insurance applicants, as well as blood pressure and build measurements. Using the results of testing for life insurance applicants who reported a Social Security number in conjunction with the Social Security Death Master File, the mortality associated with each test result was defined by age and sex. The individual mortality scores for each test were combined for each individual and a composite mortality risk score was developed. This score was then tested against the insurance applicant dataset to evaluate its ability to discriminate risk across age and sex. The composite risk score was highly predictive of all-cause mortality risk in a linear manner from the best to worst quintile of scores in a nearly identical fashion for each sex and decade of age. Laboratory studies, blood pressure and build from life insurance applicants can be used to create scoring that predicts all-cause mortality across age and sex. Such an approach may hold promise for preventative health screening as well.

An effective medium approach to modelling the pressure-dependent electrical properties of porous rocks

NASA Astrophysics Data System (ADS)

Han, Tongcheng

2018-07-01

Understanding the electrical properties of rocks under varying pressure is important for a variety of geophysical applications. This study proposes an approach to modelling the pressure-dependent electrical properties of porous rocks based on an effective medium model. The so-named Textural model uses the aspect ratios and pressure-dependent volume fractions of the pores and the aspect ratio and electrical conductivity of the matrix grains. The pores were represented by randomly oriented stiff and compliant spheroidal shapes with constant aspect ratios, and their pressure-dependent volume fractions were inverted from the measured variation of total porosity with differential pressure using a dual porosity model. The unknown constant stiff and compliant pore aspect ratios and the aspect ratio and electrical conductivity of the matrix grains were inverted by best fitting the modelled electrical formation factor to the measured data. Application of the approach to three sandstone samples covering a broad porosity range showed that the pressure-dependent electrical properties can be satisfactorily modelled by the proposed approach. The results demonstrate that the dual porosity concept is sufficient to explain the electrical properties of porous rocks under pressure through the effective medium model scheme.

Pressure sores and hip fractures.

PubMed

Haleem, S; Heinert, G; Parker, M J

2008-02-01

Development of pressure sores during hospital admission causes morbidity and distress to the patient, increases strain on nursing resources, delaying discharge and possibly increasing mortality. A hip fracture in elderly patients is a known high-risk factor for development of pressure sores. We aimed to determine the current incidence of pressure sores and identify those factors which were associated with an increased risk of pressure sores. We retrospectively analysed prospectively collected data of 4654 consecutive patients admitted to a single unit. One hundred and seventy-eight (3.8%) of our patients developed pressure sores. Patient factors that increased the risk of pressure sores were increased age, diabetes mellitus, a lower mental test score, a lower mobility score, a higher ASA score, lower admission haemoglobin and an intra-operative drop in blood pressure. The risk was higher in patients with an extracapsular neck of femur fracture and patients with an increased time interval between admission to hospital and surgery. Our studies indicate that while co-morbidities constitute a substantial risk in an elderly population, the increase in incidence of pressure sores can be reduced by minimising delays to surgery.

Characterizing Touch Using Pressure Data and Auto Regressive Models

PubMed Central

Laufer, Shlomi; Pugh, Carla M.; Van Veen, Barry D.

2014-01-01

Palpation plays a critical role in medical physical exams. Despite the wide range of exams, there are several reproducible and subconscious sets of maneuvers that are common to examination by palpation. Previous studies by our group demonstrated the use of manikins and pressure sensors for measuring and quantifying how physicians palpate during different physical exams. In this study we develop mathematical models that describe some of these common maneuvers. Dynamic pressure data was measured using a simplified testbed and different autoregressive models were used to describe the motion of interest. The frequency, direction and type of motion used were identified from the models. We believe these models can a provide better understanding of how humans explore objects in general and more specifically give insights to understand medical physical exams. PMID:25570335

Effect of heat/pressure on cyanidin-3-glucoside ethanol model solutions

NASA Astrophysics Data System (ADS)

Corrales, M.; Lindauer, R.; Butz, P.; Tauscher, B.

2008-07-01

The stability of cyanidin-3-glucoside (Cy3gl) in 50% ethanol model solutions under heat/pressure treatments was investigated. Cy3gl was rapidly degraded when solutions were subjected to a heat/pressure treatment. The higher the pressure and the temperature used, the higher the degradation. Moreover, the degradation was increased according to increasing holding times. Parallel to the degradation of Cy3gl several hydrolytic products were formed and identified by LC-DAD/ESI-MS. The degradation of Cy3gl was well fitted to a first order reaction (R=0.99). This study pointed out the rate of susceptibility of Cy3gl in model solutions to degrade when exposed to a heat/pressure treatment and the trigger effect of high hydrostatic pressure to hydrolyse Cy3gl. By contrast, the degradation of anthocyanins in a food matrix (red grape extract solutions) was negligible after a heat/pressure process at 600MPa, 70°C during 1h (P >0.05).

Elevated blood pressure among primary school children in Dar es salaam, Tanzania: prevalence and risk factors.

PubMed

Muhihi, Alfa J; Njelekela, Marina A; Mpembeni, Rose N M; Muhihi, Bikolimana G; Anaeli, Amani; Chillo, Omary; Kubhoja, Sulende; Lujani, Benjamin; Maghembe, Mwanamkuu; Ngarashi, Davis

2018-02-13

Whilst the burden of non-communicable diseases is increasing in developing countries, little data is available on blood pressure among Tanzanian children. This study aimed at determining the blood pressure profiles and risk factors associated with elevated blood pressure among primary school children in Dar es Salaam, Tanzania. We conducted a cross sectional survey among 446 children aged 6-17 years from 9 randomly selected primary schools in Dar es Salaam. We measured blood pressure using a standardized digital blood pressure measuring machine (Omron Digital HEM-907, Tokyo, Japan). We used an average of the three blood pressure readings for analysis. Elevated blood pressure was defined as average systolic or diastolic blood pressure ≥ 90th percentile for age, gender and height. The proportion of children with elevated blood pressure was 15.2% (pre-hypertension 4.4% and hypertension 10.8%). No significant gender differences were observed in the prevalence of elevated BP. Increasing age and overweight/obese children were significantly associated with elevated BP (p = 0.0029 and p < 0.0001) respectively. Similar associations were observed for age and overweight/obesity with hypertension. (p = 0.0506 and p < 0.0001) respectively. In multivariate analysis, age above 10 years (adjusted RR = 3.63, 95% CI = 1.03-7.82) was significantly and independently associated with elevated BP in this population of school age children. We observed a higher proportion of elevated BP in this population of school age children. Older age and overweight/obesity were associated with elevated BP. Assessment of BP and BMI should be incorporated in school health program in Tanzania to identify those at risk so that appropriate interventions can be instituted before development of associated complications.

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

PubMed

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; Barbosa e Silva, O

2013-04-01

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.

Using thresholds based on risk of cardiovascular disease to target treatment for hypertension: modelling events averted and number treated

PubMed Central

Baker, Simon; Priest, Patricia; Jackson, Rod

2000-01-01

Objective To estimate the impact of using thresholds based on absolute risk of cardiovascular disease to target drug treatment to lower blood pressure in the community. Design Modelling of three thresholds of treatment for hypertension based on the absolute risk of cardiovascular disease. 5 year risk of disease was estimated for each participant using an equation to predict risk. Net predicted impact of the thresholds on the number of people treated and the number of disease events averted over 5 years was calculated assuming a relative treatment benefit of one quarter. Setting Auckland, New Zealand. Participants 2158 men and women aged 35-79 years randomly sampled from the general electoral rolls. Main outcome measures Predicted 5 year risk of cardiovascular disease event, estimated number of people for whom treatment would be recommended, and disease events averted over 5 years at different treatment thresholds. Results 46 374 (12%) Auckland residents aged 35-79 receive drug treatment to lower their blood pressure, averting an estimated 1689 disease events over 5 years. Restricting treatment to individuals with blood pressure ⩾170/100 mm Hg and those with blood pressure between 150/90-169/99 mm Hg who have a predicted 5 year risk of disease ⩾10% would increase the net number for whom treatment would be recommended by 19 401. This 42% relative increase is predicted to avert 1139/1689 (68%) additional disease events overall over 5 years compared with current treatment. If the threshold for 5 year risk of disease is set at 15% the number recommended for treatment increases by <10% but about 620/1689 (37%) additional events can be averted. A 20% threshold decreases the net number of patients recommended for treatment by about 10% but averts 204/1689 (12%) more disease events than current treatment. Conclusions Implementing treatment guidelines that use treatment thresholds based on absolute risk could significantly improve the efficiency of drug treatment to

Development and validity of a new model for assessing pressure redistribution properties of support surfaces.

PubMed

Matsuo, Junko; Sugama, Junko; Sanada, Hiromi; Okuwa, Mayumi; Nakatani, Toshio; Konya, Chizuko; Sakamoto, Jirou

2011-05-01

Pressure ulcers are a common problem, especially in older patients. In Japan, most institutionalized older people are malnourished and show extreme bony prominence (EBP). EBP is a significant factor in the development of pressure ulcers due to increased interface pressure concentrated at the skin surface over the EBP. The use of support surfaces is recommended for the prophylaxis of pressure ulcers. However, the present equivocal criteria for evaluating the pressure redistribution of support surfaces are inadequate. Since pressure redistribution is influenced by physique and posture, evaluations using human subjects are limited. For this reason, models that can substitute for humans are necessary. We developed a new EBP model based on the anthropometric measurements, including pelvic inclination, of 100 bedridden elderly people. A comparison between the pressure distribution charts of our model and bedridden elderly subjects demonstrated that maximum contact pressure values, buttock contact pressure values, and bone prominence rates corresponded closely. This indicates that the model provides a good approximation of the features of elderly people with EBP. We subsequently examined the validity of the model through quantitative assessment of pressure redistribution functions consisting of immersion, envelopment, and contact area change. The model was able to detect differences in the hardness of urethane foam, differences in the internal pressure of an air mattress, and sequential changes during the pressure switching mode. These results demonstrate the validity of our new buttock model in evaluating pressure redistribution for a variety of surfaces. Copyright © 2010 Tissue Viability Society. Published by Elsevier Ltd. All rights reserved.

Exercise Blood Pressure and the Risk for Future Hypertension Among Normotensive Middle‐Aged Adults

PubMed Central

Berger, Assaf; Grossman, Ehud; Katz, Moshe; Kivity, Shaye; Klempfner, Robert; Segev, Shlomo; Goldenberg, Ilan; Sidi, Yehezkel; Maor, Elad

2015-01-01

Background The aim of the present study was to examine whether exercise blood pressure can be used to predict the development of hypertension in normotensive middle‐aged adults. Methods and Results We investigated 7082 normotensive subjects who were annually screened in a tertiary medical center and completed maximal treadmill exercise tests at each visit. After the initial 3 years, subjects were divided into approximate quartiles according to their average exercise systolic and diastolic blood pressure responses (≤158; 158 to 170; 170 to 183; ≥183 mm Hg for systolic blood pressure and ≤73; 73 to 77; 77 to 82; ≥82 mm Hg for diastolic blood pressure). Mean age of the study population was 48±9 years and 73% were men. Average baseline resting blood pressure was 120/77±12/7 mm Hg. During a follow‐up of 5±3 years, 1036 (14.6%) subjects developed hypertension. The cumulative probability of new‐onset hypertension at 5 years was significantly increased with increasing quartiles of exercise systolic blood pressure (5%, 9%, 17%, and 35%, respectively; P<0.001), with a similar association shown for diastolic blood pressure. After adjustment for baseline resting blood pressure and clinical parameters, each 5‐mm Hg increments in exercise either systolic or diastolic blood pressures were independently associated with respective 11% (P<0.001) and 30% (P<0.001) increased risk for the development of hypertension. Conclusions In normotensive middle‐aged individuals, blood pressure response to exercise is associated with future development of hypertension. PMID:25904593

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.

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.

A steady state pressure drop model for screen channel liquid acquisition devices

NASA Astrophysics Data System (ADS)

Hartwig, J. W.; Darr, S. R.; McQuillen, J. B.; Rame, E.; Chato, D. J.

2014-11-01

This paper presents the derivation of a simplified one dimensional (1D) steady state pressure drop model for flow through a porous liquid acquisition device (LAD) inside a cryogenic propellant tank. Experimental data is also presented from cryogenic LAD tests in liquid hydrogen (LH2) and liquid oxygen (LOX) to compare against the simplified model and to validate the model at cryogenic temperatures. The purpose of the experiments was to identify the various pressure drop contributions in the analytical model which govern LAD channel behavior during dynamic, steady state outflow. LH2 pipe flow of LAD screen samples measured the second order flow-through-screen (FTS) pressure drop, horizontal LOX LAD outflow tests determined the relative magnitude of the third order frictional and dynamic losses within the channel, while LH2 inverted vertical outflow tests determined the magnitude of the first order hydrostatic pressure loss and validity of the full 1D model. When compared to room temperature predictions, the FTS pressure drop is shown to be temperature dependent, with a significant increase in flow resistance at LH2 temperatures. Model predictions of frictional and dynamic losses down the channel compare qualitatively with LOX LADs data. Meanwhile, the 1D model predicted breakdown points track the trends in the LH2 inverted outflow experimental results, with discrepancies being due to a non-uniform injection velocity across the LAD screen not accounted for in the model.

Stress modeling of microdiaphragm pressure sensors

NASA Technical Reports Server (NTRS)

Tack, P. C.; Busta, H. H.

1986-01-01

A finite element program analysis was used to model the stress distribution of two monocrystalline silicon diaphragm pressure sensors. One configuration consists of an anisotropically backside etched diaphragm into a 250 micron thick, (100) oriented, silicon wafer. The diaphragm and total chip dimensions are given. The device is rigidly clamped on the back to a support substrate. Another configuration consists of a monocrystalline, (100), microdiaphragm which is formed on top of the wafer and whose area is reduced by a factor of 25 over the first configuration. The diaphragm is rigidly clamped to the silicon wafer. The stresses were calculated at a gauge pressure of 300 mm Hg and used to estimate the piezoresistive responses of resistor elements which were placed parallel and perpendicular near the diaphragm edges.

Targets and self-management for the control of blood pressure in stroke and at risk groups (TASMIN-SR): protocol for a randomised controlled trial.

PubMed

O'Brien, Claire; Bray, Emma P; Bryan, Stirling; Greenfield, Sheila M; Haque, M Sayeed; Hobbs, F D Richard; Jones, Miren I; Jowett, Sue; Kaambwa, Billingsley; Little, Paul; Mant, Jonathan; Penaloza, Cristina; Schwartz, Claire; Shackleford, Helen; Varghese, Jinu; Williams, Bryan; McManus, Richard J

2013-03-23

Self-monitoring of hypertension with self-titration of antihypertensives (self-management) results in lower systolic blood pressure for at least one year. However, few people in high risk groups have been evaluated to date and previous work suggests a smaller effect size in these groups. This trial therefore aims to assess the added value of self-management in high risk groups over and above usual care. The targets and self-management for the control of blood pressure in stroke and at risk groups (TASMIN-SR) trial will be a pragmatic primary care based, unblinded, randomised controlled trial of self-management of blood pressure (BP) compared to usual care. Eligible patients will have a history of stroke, coronary heart disease, diabetes or chronic kidney disease and will be recruited from primary care. Participants will be individually randomised to either usual care or self-management. The primary outcome of the trial will be difference in office SBP between intervention and control groups at 12 months adjusted for baseline SBP and covariates. 540 patients will be sufficient to detect a difference in SBP between self-management and usual care of 5 mmHg with 90% power. Secondary outcomes will include self-efficacy, lifestyle behaviours, health-related quality of life and adverse events. An economic analysis will consider both within trial costs and a model extrapolating the results thereafter. A qualitative analysis will gain insights into patients' views, experiences and decision making processes. The results of the trial will be directly applicable to primary care in the UK. If successful, self-management of blood pressure in people with stroke and other high risk conditions would be applicable to many hundreds of thousands of individuals in the UK and beyond. ISRCTN87171227.

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

An ex vivo porcine skin model to evaluate pressure-reducing devices of different mechanical properties used for pressure ulcer prevention.

PubMed

Yeung, Ching-Yan C; Holmes, David F; Thomason, Helen A; Stephenson, Christian; Derby, Brian; Hardman, Matthew J

2016-11-01

Pressure ulcers are complex wounds caused by pressure- and shear-induced trauma to skin and underlying tissues. Pressure-reducing devices, such as dressings, have been shown to successfully reduce pressure ulcer incidence, when used in adjunct to pressure ulcer preventative care. While pressure-reducing devices are available in a range of materials, with differing mechanical properties, understanding of how a material's mechanical properties will influence clinical efficacy remains limited. The aim of this study was to establish a standardized ex vivo model to allow comparison of the cell protection potential of two gel-like pressure-reducing devices with differing mechanical properties (elastic moduli of 77 vs. 35 kPa). The devices also displayed differing energy dissipation under compressive loading, and resisted strain differently under constant load in compressive creep tests. To evaluate biological efficacy we employed a new ex vivo porcine skin model, with a confirmed elastic moduli closely matching that of human skin (113 vs. 119 kPa, respectively). Static loads up to 20 kPa were applied to porcine skin ex vivo with subsequent evaluation of pressure-induced cell death and cytokine release. Pressure application alone increased the percentage of epidermal apoptotic cells from less than 2% to over 40%, and increased cellular secretion of the pro-inflammatory cytokine TNF-alpha. Co-application of a pressure-reducing device significantly reduced both cellular apoptosis and cytokine production, protecting against cellular damage. These data reveal new insight into the relationship between mechanical properties of pressure-reducing devices and their biological effects. After appropriate validation of these results in clinical pressure ulcer prevention with all tissue layers present between the bony prominence and external surface, this ex vivo porcine skin model could be widely employed to optimize design and evaluation of devices aimed at reducing pressure

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

Risk assessment for prevention of morbidity and mortality: lessons for pressure ulcer prevention.

PubMed

Reynolds, T M

2008-11-01

Medicine has changed from being a reactive process that attempts to alleviate disease only when it is clinically evident to a proactive one in which it is hoped that early intervention may reduce the impact of disease or even it developing at all. In moving the focus of treatment, this inevitably means that a greater number of individuals with lesser disease burdens are treated. The logical end-point of this process is to provide preventative measures for the entire population but this can only be done if the economic costs and negative effects of treatment are out-weighed by the benefits. In the case of pressure ulcers, it is self-evident that prevention is extremely beneficial to patients. However, the cost of some of the equipment used for prevention can be high, and therefore, the balance between the optimum level of provision, the purposes of prevention and the available funding becomes critical. Consequently a screening mechanism to better match susceptible patients with resources is essential. There are, however, many problems with such screening techniques. By looking at other specialties, we can see that it is vital to know the natural history of the disease: PSA testing reveals many men who would have died never having known they had prostate cancer, thus giving them years of worry and morbidity they would probably not previously have suffered; cardiovascular risk screening is so imprecise that risk estimates are of questionable utility; antenatal Down's syndrome risk screening is prone to data-related problems that can unexpectedly reduce the effectiveness of the test. In pressure ulcer screening, there are many tools currently in use, but few (possibly none) are really effective. Finally, this paper details some suggestions for future research to combine risk tests that may offer a prospect for improving ulcer risk screening tools.

Semiempirical models of shear modulus at shock temperatures and pressures

NASA Astrophysics Data System (ADS)

Elkin, Vaytcheslav; Mikhaylov, Vadim; Mikhaylova, Tatiana

2011-06-01

The work is devoted to a comparison of capabilities the Steinberg-Cochran-Guinan and Burakovsky-Preston models of shear modulus offer for the description of experimental and calculated (ab initio) data at temperatures and pressures representative of solid state behind the shock front. Also, the SCG model is modernized by changing from the (P,V) variables to the (V,T) ones and adding a free parameter. The resulted model is then referred to as the (V,T)-model. The three models are tested for 9 metals (Al, Be, Cu, K, Na, Mg, Mo, W, Ta) with using ab initio and experimental values of shear modulus in a wide range of pressures as well as longitudinal sound velocities behind the shock front.

A model for the influence of pressure on the bulk modulus and the influence of temperature on the solidification pressure for liquid lubricants

NASA Technical Reports Server (NTRS)

Jacobson, B. O.; Vinet, P.

1986-01-01

Two pressure chambers, for compression experiments with liquids from zero to 2.2 GPa pressure, are described. The experimentally measured compressions are then compared to theoretical values given by an isothermal model of equation of state recently introduced for solids. The model describes the pressure and bulk modulus as a function of compression for different types of lubricants with a very high accuracy up to the pressure limit of the high pressure chamber used (2.2 GPa). In addition the influence of temperature on static solidification pressure was found to be a simple function of the thermal expansion of the fluid.

Risk factors for pressure sores in adult patients with myelomeningocele--a questionnaire-based study.

PubMed

Plaum, Pål-Erik; Riemer, Gunnar; Frøslie, Kathrine Frey

2006-12-29

Myelomeningocele (MMC) is a part of a complex neural tube defect and a disorder of the cerebrospinal fluid system. Pressure sores are a frequent complication for patients with MMC. Little is known about the risk factors for pressure sores in adults with MMC. The aim of this study was to investigate an association between the presence of pressure sores and other patient characteristics, in order to develop an improved strategy for the management of sores. A structured questionnaire regarding sores, medical condition, function and living factors was designed and sent to the 193 patients with MMC registered in the year 2003 at TRS, a National Centre for Rare Disorders in Norway. Out of 193 total, 87 patients participated and 71 patients (82%) reported sores; 26 (30%) at the time of the interview and 45 (52%) during the last 5 years. Sores were mostly localized on toes and feet and occurred exclusively in regions with reduced or missing sensibility. A significant association was found between sores and memory deficit (p = 0.02), Arnold Chiari malformation (p = 0.02) and a record of previous sores (p = 0.004). Sores were not significantly associated with hydrocephalus, syringomyelia, nutrition, body mass index, smoking, physical activity, employment or living together with other persons. Some patients (18, 21%) reported skin inspection by others and the remainder relied on self-inspection. Patients with sensory deficit, memory problems, and Arnold Chiari malformation had a higher risk of having pressure sores. This patient group needs improved skin inspection routines and sore treatment.

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

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.

Pressure Ulcer Prevention

PubMed Central

2009-01-01

Executive Summary In April 2008, the Medical Advisory Secretariat began an evidence-based review of the literature concerning pressure ulcers. Please visit the Medical Advisory Secretariat Web site, http://www.health.gov.on.ca/english/providers/program/mas/tech/tech_mn.html to review these titles that are currently available within the Pressure Ulcers series. Pressure ulcer prevention: an evidence based analysis The cost-effectiveness of prevention strategies for pressure ulcers in long-term care homes in Ontario: projections of the Ontario Pressure Ulcer Model (field evaluation) Management of chronic pressure ulcers: an evidence-based analysis (anticipated pubicstion date - mid-2009) Purpose A pressure ulcer, also known as a pressure sore, decubitus ulcer, or bedsore, is defined as a localized injury to the skin/and or underlying tissue occurring most often over a bony prominence and caused by pressure, shear, or friction, alone or in combination. (1) Those at risk for developing pressure ulcers include the elderly and critically ill as well as persons with neurological impairments and those who suffer conditions associated with immobility. Pressure ulcers are graded or staged with a 4-point classification system denoting severity. Stage I represents the beginnings of a pressure ulcer and stage IV, the severest grade, consists of full thickness tissue loss with exposed bone, tendon, and or muscle. (1) In a 2004 survey of Canadian health care settings, Woodbury and Houghton (2) estimated that the prevalence of pressure ulcers at a stage 1 or greater in Ontario ranged between 13.1% and 53% with nonacute health care settings having the highest prevalence rate (Table 1). Executive Summary Table 1: Prevalence of Pressure Ulcers* Setting Canadian Prevalence,% (95% CI) Ontario Prevalence,Range % (n) Acute care 25 (23.8–26.3) 23.9–29.7 (3418) Nonacute care† 30 (29.3–31.4) 30.0–53.3 (1165) Community care 15 (13.4–16.8) 13.2 (91) Mixed health care‡ 22 (20.9�

Development of solar wind shock models with tensor plasma pressure for data analysis

NASA Technical Reports Server (NTRS)

Abraham-Shrauner, B.

1975-01-01

The development of solar wind shock models with tensor plasma pressure and the comparison of some of the shock models with the satellite data from Pioneer 6 through Pioneer 9 are reported. Theoretically, difficulties were found in non-turbulent fluid shock models for tensor pressure plasmas. For microscopic shock theories nonlinear growth caused by plasma instabilities was frequently not clearly demonstrated to lead to the formation of a shock. As a result no clear choice for a shock model for the bow shock or interplanetary tensor pressure shocks emerged.

Osmotic Pressure of Aqueous Chondroitin Sulfate Solution: A Molecular Modeling Investigation

PubMed Central

Bathe, Mark; Rutledge, Gregory C.; Grodzinsky, Alan J.; Tidor, Bruce

2005-01-01

The osmotic pressure of chondroitin sulfate (CS) solution in contact with an aqueous 1:1 salt reservoir of fixed ionic strength is studied using a recently developed coarse-grained molecular model. The effects of sulfation type (4- vs. 6-sulfation), sulfation pattern (statistical distribution of sulfate groups along a chain), ionic strength, CS intrinsic stiffness, and steric interactions on CS osmotic pressure are investigated. At physiological ionic strength (0.15 M NaCl), the sulfation type and pattern, as measured by a standard statistical description of copolymerization, are found to have a negligible influence on CS osmotic pressure, which depends principally on the mean volumetric fixed charge density. The intrinsic backbone stiffness characteristic of polysaccharides such as CS, however, is demonstrated to contribute significantly to its osmotic pressure behavior, which is similar to that of a solution of charged rods for the 20-disaccharide chains considered. Steric excluded volume is found to play a negligible role in determining CS osmotic pressure at physiological ionic strength due to the dominance of repulsive intermolecular electrostatic interactions that maintain chains maximally spaced in that regime, whereas at high ionic-strength steric interactions become dominant due to electrostatic screening. Osmotic pressure predictions are compared to experimental data and to well-established theoretical models including the Donnan theory and the Poisson-Boltzmann cylindrical cell model. PMID:16055525

University of North Carolina Caries Risk Assessment Study: comparisons of high risk prediction, any risk prediction, and any risk etiologic models.

PubMed

Beck, J D; Weintraub, J A; Disney, J A; Graves, R C; Stamm, J W; Kaste, L M; Bohannan, H M

1992-12-01

The purpose of this analysis is to compare three different statistical models for predicting children likely to be at risk of developing dental caries over a 3-yr period. Data are based on 4117 children who participated in the University of North Carolina Caries Risk Assessment Study, a longitudinal study conducted in the Aiken, South Carolina, and Portland, Maine areas. The three models differed with respect to either the types of variables included or the definition of disease outcome. The two "Prediction" models included both risk factor variables thought to cause dental caries and indicator variables that are associated with dental caries, but are not thought to be causal for the disease. The "Etiologic" model included only etiologic factors as variables. A dichotomous outcome measure--none or any 3-yr increment, was used in the "Any Risk Etiologic model" and the "Any Risk Prediction Model". Another outcome, based on a gradient measure of disease, was used in the "High Risk Prediction Model". The variables that are significant in these models vary across grades and sites, but are more consistent among the Etiologic model than the Predictor models. However, among the three sets of models, the Any Risk Prediction Models have the highest sensitivity and positive predictive values, whereas the High Risk Prediction Models have the highest specificity and negative predictive values. Considerations in determining model preference are discussed.

[A Structural Equation Model of Pressure Ulcer Prevention Action in Clinical Nurses].

PubMed

Lee, Sook Ja; Park, Ok Kyoung; Park, Mi Yeon

2016-08-01

The purpose of this study was to construct and test a structural equation model for pressure ulcer prevention action by clinical nurses. The Health Belief Model and the Theory of Planned Behavior were used as the basis for the study. A structured questionnaire was completed by 251 clinical nurses to analyze the relationships between concepts of perceived benefits, perceived barriers, attitude, subjective norm, perceived control, intention to perform action and behavior. SPSS 22.0 and AMOS 22.0 programs were used to analyze the efficiency of the hypothesized model and calculate the direct and indirect effects of factors affecting pressure ulcer prevention action among clinical nurses. The model fitness statistics of the hypothetical model fitted to the recommended levels. Attitude, subjective norm and perceived control on pressure ulcer prevention action explained 64.2% for intention to perform prevention action. The major findings of this study indicate that it is essential to recognize improvement in positive attitude for pressure ulcer prevention action and a need for systematic education programs to increase perceived control for prevention action.

Foot Modeling and Smart Plantar Pressure Reconstruction from Three Sensors

PubMed Central

Ghaida, Hussein Abou; Mottet, Serge; Goujon, Jean-Marc

2014-01-01

In order to monitor pressure under feet, this study presents a biomechanical model of the human foot. The main elements of the foot that induce the plantar pressure distribution are described. Then the link between the forces applied at the ankle and the distribution of the plantar pressure is established. Assumptions are made by defining the concepts of a 3D internal foot shape, which can be extracted from the plantar pressure measurements, and a uniform elastic medium, which describes the soft tissues behaviour. In a second part, we show that just 3 discrete pressure sensors per foot are enough to generate real time plantar pressure cartographies in the standing position or during walking. Finally, the generated cartographies are compared with pressure cartographies issued from the F-SCAN system. The results show 0.01 daN (2% of full scale) average error, in the standing position. PMID:25400713

Foot modeling and smart plantar pressure reconstruction from three sensors.

PubMed

Ghaida, Hussein Abou; Mottet, Serge; Goujon, Jean-Marc

2014-01-01

In order to monitor pressure under feet, this study presents a biomechanical model of the human foot. The main elements of the foot that induce the plantar pressure distribution are described. Then the link between the forces applied at the ankle and the distribution of the plantar pressure is established. Assumptions are made by defining the concepts of a 3D internal foot shape, which can be extracted from the plantar pressure measurements, and a uniform elastic medium, which describes the soft tissues behaviour. In a second part, we show that just 3 discrete pressure sensors per foot are enough to generate real time plantar pressure cartographies in the standing position or during walking. Finally, the generated cartographies are compared with pressure cartographies issued from the F-SCAN system. The results show 0.01 daN (2% of full scale) average error, in the standing position.

Multilevel joint competing risk models

NASA Astrophysics Data System (ADS)

Karunarathna, G. H. S.; Sooriyarachchi, M. R.

2017-09-01

Joint modeling approaches are often encountered for different outcomes of competing risk time to event and count in many biomedical and epidemiology studies in the presence of cluster effect. Hospital length of stay (LOS) has been the widely used outcome measure in hospital utilization due to the benchmark measurement for measuring multiple terminations such as discharge, transferred, dead and patients who have not completed the event of interest at the follow up period (censored) during hospitalizations. Competing risk models provide a method of addressing such multiple destinations since classical time to event models yield biased results when there are multiple events. In this study, the concept of joint modeling has been applied to the dengue epidemiology in Sri Lanka, 2006-2008 to assess the relationship between different outcomes of LOS and platelet count of dengue patients with the district cluster effect. Two key approaches have been applied to build up the joint scenario. In the first approach, modeling each competing risk separately using the binary logistic model, treating all other events as censored under the multilevel discrete time to event model, while the platelet counts are assumed to follow a lognormal regression model. The second approach is based on the endogeneity effect in the multilevel competing risks and count model. Model parameters were estimated using maximum likelihood based on the Laplace approximation. Moreover, the study reveals that joint modeling approach yield more precise results compared to fitting two separate univariate models, in terms of AIC (Akaike Information Criterion).

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.

Exercise blood pressure and the risk for future hypertension among normotensive middle-aged adults.

PubMed

Berger, Assaf; Grossman, Ehud; Katz, Moshe; Kivity, Shaye; Klempfner, Robert; Segev, Shlomo; Goldenberg, Ilan; Sidi, Yehezkel; Maor, Elad

2015-04-22

The aim of the present study was to examine whether exercise blood pressure can be used to predict the development of hypertension in normotensive middle-aged adults. We investigated 7082 normotensive subjects who were annually screened in a tertiary medical center and completed maximal treadmill exercise tests at each visit. After the initial 3 years, subjects were divided into approximate quartiles according to their average exercise systolic and diastolic blood pressure responses (≤158; 158 to 170; 170 to 183; ≥183 mm Hg for systolic blood pressure and ≤73; 73 to 77; 77 to 82; ≥82 mm Hg for diastolic blood pressure). Mean age of the study population was 48 ± 9 years and 73% were men. Average baseline resting blood pressure was 120/77 ± 12/7 mm Hg. During a follow-up of 5 ± 3 years, 1036 (14.6%) subjects developed hypertension. The cumulative probability of new-onset hypertension at 5 years was significantly increased with increasing quartiles of exercise systolic blood pressure (5%, 9%, 17%, and 35%, respectively; P<0.001), with a similar association shown for diastolic blood pressure. After adjustment for baseline resting blood pressure and clinical parameters, each 5-mm Hg increments in exercise either systolic or diastolic blood pressures were independently associated with respective 11% (P<0.001) and 30% (P<0.001) increased risk for the development of hypertension. In normotensive middle-aged individuals, blood pressure response to exercise is associated with future development of hypertension. © 2015 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.

Extracting risk modeling information from medical articles.

PubMed

Deleris, Léa A; Sacaleanu, Bogdan; Tounsi, Lamia

2013-01-01

Risk modeling in healthcare is both ubiquitous and in its infancy. On the one hand, a significant proportion of medical research focuses on determining the factors that influence the incidence, severity and treatment of diseases, which is a form of risk identification. Those studies typically investigate the micro-level of risk modeling, i.e., the existence of dependences between a reduced set of hypothesized (or demonstrated) risk factors and a focus disease or treatment. On the other hand, the macro-level of risk modeling, i.e., articulating how a large number of such risk factors interact to affect diseases and treatments is not widespread, though essential for medical decision support modeling. By exploiting advances in natural language processing, we believe that information contained in unstructured texts such as medical articles could be extracted to facilitate aggregation into macro-level risk models.

A continuum model for pressure-flow relationship in human pulmonary circulation.

PubMed

Huang, Wei; Zhou, Qinlian; Gao, Jian; Yen, R T

2011-06-01

A continuum model was introduced to analyze the pressure-flow relationship for steady flow in human pulmonary circulation. The continuum approach was based on the principles of continuum mechanics in conjunction with detailed measurement of vascular geometry, vascular elasticity and blood rheology. The pulmonary arteries and veins were considered as elastic tubes and the "fifth-power law" was used to describe the pressure-flow relationship. For pulmonary capillaries, the "sheet-flow" theory was employed and the pressure-flow relationship was represented by the "fourth-power law". In this paper, the pressure-flow relationship for the whole pulmonary circulation and the longitudinal pressure distribution along the streamlines were studied. Our computed data showed general agreement with the experimental data for the normal subjects and the patients with mitral stenosis and chronic bronchitis in the literature. In conclusion, our continuum model can be used to predict the changes of steady flow in human pulmonary circulation.

New Models for Velocity/Pressure-Gradient Correlations in Turbulent Boundary Layers

NASA Astrophysics Data System (ADS)

Poroseva, Svetlana; Murman, Scott

2014-11-01

To improve the performance of Reynolds-Averaged Navier-Stokes (RANS) turbulence models, one has to improve the accuracy of models for three physical processes: turbulent diffusion, interaction of turbulent pressure and velocity fluctuation fields, and dissipative processes. The accuracy of modeling the turbulent diffusion depends on the order of a statistical closure chosen as a basis for a RANS model. When the Gram-Charlier series expansions for the velocity correlations are used to close the set of RANS equations, no assumption on Gaussian turbulence is invoked and no unknown model coefficients are introduced into the modeled equations. In such a way, this closure procedure reduces the modeling uncertainty of fourth-order RANS (FORANS) closures. Experimental and direct numerical simulation data confirmed the validity of using the Gram-Charlier series expansions in various flows including boundary layers. We will address modeling the velocity/pressure-gradient correlations. New linear models will be introduced for the second- and higher-order correlations applicable to two-dimensional incompressible wall-bounded flows. Results of models' validation with DNS data in a channel flow and in a zero-pressure gradient boundary layer over a flat plate will be demonstrated. A part of the material is based upon work supported by NASA under award NNX12AJ61A.

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

A pore-pressure diffusion model for estimating landslide-inducing rainfall

USGS Publications Warehouse

Reid, M.E.

1994-01-01

Many types of landslide movement are induced by large rainstorms, and empirical rainfall intensity/duration thresholds for initiating movement have been determined for various parts of the world. In this paper, I present a simple pressure diffusion model that provides a physically based hydrologic link between rainfall intensity/duration at the ground surface and destabilizing pore-water pressures at depth. The model approximates rainfall infiltration as a sinusoidally varying flux over time and uses physical parameters that can be determined independently. Using a comprehensive data set from an intensively monitored landslide, I demonstrate that the model is capable of distinguishing movement-inducing rainstorms. -Author

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.

Under pressure: response urgency modulates striatal and insula activity during decision-making under risk.

PubMed

Jones, Catherine L; Minati, Ludovico; Harrison, Neil A; Ward, Jamie; Critchley, Hugo D

2011-01-01

When deciding whether to bet in situations that involve potential monetary loss or gain (mixed gambles), a subjective sense of pressure can influence the evaluation of the expected utility associated with each choice option. Here, we explored how gambling decisions, their psychophysiological and neural counterparts are modulated by an induced sense of urgency to respond. Urgency influenced decision times and evoked heart rate responses, interacting with the expected value of each gamble. Using functional MRI, we observed that this interaction was associated with changes in the activity of the striatum, a critical region for both reward and choice selection, and within the insula, a region implicated as the substrate of affective feelings arising from interoceptive signals which influence motivational behavior. Our findings bridge current psychophysiological and neurobiological models of value representation and action-programming, identifying the striatum and insular cortex as the key substrates of decision-making under risk and urgency.

[Theoretical model study about the application risk of high risk medical equipment].

PubMed

Shang, Changhao; Yang, Fenghui

2014-11-01

Research for establishing a risk monitoring theoretical model of high risk medical equipment at applying site. Regard the applying site as a system which contains some sub-systems. Every sub-system consists of some risk estimating indicators. After quantizing of each indicator, the quantized values are multiplied with corresponding weight and then the products are accumulated. Hence, the risk estimating value of each subsystem is attained. Follow the calculating method, the risk estimating values of each sub-system are multiplied with corresponding weights and then the product is accumulated. The cumulative sum is the status indicator of the high risk medical equipment at applying site. The status indicator reflects the applying risk of the medical equipment at applying site. Establish a risk monitoring theoretical model of high risk medical equipment at applying site. The model can monitor the applying risk of high risk medical equipment at applying site dynamically and specially.

Effect of Pore Pressure on Slip Failure of an Impermeable Fault: A Coupled Micro Hydro-Geomechanical Model

NASA Astrophysics Data System (ADS)

Yang, Z.; Juanes, R.

2015-12-01

The geomechanical processes associated with subsurface fluid injection/extraction is of central importance for many industrial operations related to energy and water resources. However, the mechanisms controlling the stability and slip motion of a preexisting geologic fault remain poorly understood and are critical for the assessment of seismic risk. In this work, we develop a coupled hydro-geomechanical model to investigate the effect of fluid injection induced pressure perturbation on the slip behavior of a sealing fault. The model couples single-phase flow in the pores and mechanics of the solid phase. Granular packs (see example in Fig. 1a) are numerically generated where the grains can be either bonded or not, depending on the degree of cementation. A pore network is extracted for each granular pack with pore body volumes and pore throat conductivities calculated rigorously based on geometry of the local pore space. The pore fluid pressure is solved via an explicit scheme, taking into account the effect of deformation of the solid matrix. The mechanics part of the model is solved using the discrete element method (DEM). We first test the validity of the model with regard to the classical one-dimensional consolidation problem where an analytical solution exists. We then demonstrate the ability of the coupled model to reproduce rock deformation behavior measured in triaxial laboratory tests under the influence of pore pressure. We proceed to study the fault stability in presence of a pressure discontinuity across the impermeable fault which is implemented as a plane with its intersected pore throats being deactivated and thus obstructing fluid flow (Fig. 1b, c). We focus on the onset of shear failure along preexisting faults. We discuss the fault stability criterion in light of the numerical results obtained from the DEM simulations coupled with pore fluid flow. The implication on how should faults be treated in a large-scale continuum model is also presented.

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

2017-03-01

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. Copyright © 2017 American Society of Hypertension. All rights reserved.

Modeling of low pressure plasma sources for microelectronics fabrication

NASA Astrophysics Data System (ADS)

Agarwal, Ankur; Bera, Kallol; Kenney, Jason; Likhanskii, Alexandre; Rauf, Shahid

2017-10-01

Chemically reactive plasmas operating in the 1 mTorr-10 Torr pressure range are widely used for thin film processing in the semiconductor industry. Plasma modeling has come to play an important role in the design of these plasma processing systems. A number of 3-dimensional (3D) fluid and hybrid plasma modeling examples are used to illustrate the role of computational investigations in design of plasma processing hardware for applications such as ion implantation, deposition, and etching. A model for a rectangular inductively coupled plasma (ICP) source is described, which is employed as an ion source for ion implantation. It is shown that gas pressure strongly influences ion flux uniformity, which is determined by the balance between the location of plasma production and diffusion. The effect of chamber dimensions on plasma uniformity in a rectangular capacitively coupled plasma (CCP) is examined using an electromagnetic plasma model. Due to high pressure and small gap in this system, plasma uniformity is found to be primarily determined by the electric field profile in the sheath/pre-sheath region. A 3D model is utilized to investigate the confinement properties of a mesh in a cylindrical CCP. Results highlight the role of hole topology and size on the formation of localized hot-spots. A 3D electromagnetic plasma model for a cylindrical ICP is used to study inductive versus capacitive power coupling and how placement of ground return wires influences it. Finally, a 3D hybrid plasma model for an electron beam generated magnetized plasma is used to understand the role of reactor geometry on plasma uniformity in the presence of E  ×  B drift.

The 12-foot pressure wind tunnel restoration project model support systems

NASA Technical Reports Server (NTRS)

Sasaki, Glen E.

1992-01-01

The 12 Foot Pressure Wind Tunnel is a variable density, low turbulence wind tunnel that operates at subsonic speeds, and up to six atmospheres total pressure. The restoration of this facility is of critical importance to the future of the U.S. aerospace industry. As part of this project, several state of the art model support systems are furnished to provide an optimal balance between aerodynamic and operational efficiency parameters. Two model support systems, the Rear Strut Model Support, and the High Angle of Attack Model Support are discussed. This paper covers design parameters, constraints, development, description, and component selection.

Comparative Cost-Effectiveness of Conservative or Intensive Blood Pressure Treatment Guidelines in Adults Aged 35-74 Years: The Cardiovascular Disease Policy Model.

PubMed

Moise, Nathalie; Huang, Chen; Rodgers, Anthony; Kohli-Lynch, Ciaran N; Tzong, Keane Y; Coxson, Pamela G; Bibbins-Domingo, Kirsten; Goldman, Lee; Moran, Andrew E

2016-07-01

The population health effect and cost-effectiveness of implementing intensive blood pressure goals in high-cardiovascular disease (CVD) risk adults have not been described. Using the CVD Policy Model, CVD events, treatment costs, quality-adjusted life years, and drug and monitoring costs were simulated over 2016 to 2026 for hypertensive patients aged 35 to 74 years. We projected the effectiveness and costs of hypertension treatment according to the 2003 Joint National Committee (JNC)-7 or 2014 JNC8 guidelines, and then for adults aged ≥50 years, we assessed the cost-effectiveness of adding an intensive goal of systolic blood pressure <120 mm Hg for patients with CVD, chronic kidney disease, or 10-year CVD risk ≥15%. Incremental cost-effectiveness ratios <$50 000 per quality-adjusted life years gained were considered cost-effective. JNC7 strategies treat more patients and are more costly to implement compared with JNC8 strategies. Adding intensive systolic blood pressure goals for high-risk patients prevents an estimated 43 000 and 35 000 annual CVD events incremental to JNC8 and JNC7, respectively. Intensive strategies save costs in men and are cost-effective in women compared with JNC8 alone. At a willingness-to-pay threshold of $50 000 per quality-adjusted life years gained, JNC8+intensive had the highest probability of cost-effectiveness in women (82%) and JNC7+intensive the highest probability of cost-effectiveness in men (100%). Assuming higher drug and monitoring costs, adding intensive goals for high-risk patients remained consistently cost-effective in men, but not always in women. Among patients aged 35 to 74 years, adding intensive blood pressure goals for high-risk groups to current national hypertension treatment guidelines prevents additional CVD deaths while saving costs provided that medication costs are controlled. © 2016 American Heart Association, Inc.

Modeling methods for merging computational and experimental aerodynamic pressure data

NASA Astrophysics Data System (ADS)

Haderlie, Jacob C.

This research describes a process to model surface pressure data sets as a function of wing geometry from computational and wind tunnel sources and then merge them into a single predicted value. The described merging process will enable engineers to integrate these data sets with the goal of utilizing the advantages of each data source while overcoming the limitations of both; this provides a single, combined data set to support analysis and design. The main challenge with this process is accurately representing each data source everywhere on the wing. Additionally, this effort demonstrates methods to model wind tunnel pressure data as a function of angle of attack as an initial step towards a merging process that uses both location on the wing and flow conditions (e.g., angle of attack, flow velocity or Reynold's number) as independent variables. This surrogate model of pressure as a function of angle of attack can be useful for engineers that need to predict the location of zero-order discontinuities, e.g., flow separation or normal shocks. Because, to the author's best knowledge, there is no published, well-established merging method for aerodynamic pressure data (here, the coefficient of pressure Cp), this work identifies promising modeling and merging methods, and then makes a critical comparison of these methods. Surrogate models represent the pressure data for both data sets. Cubic B-spline surrogate models represent the computational simulation results. Machine learning and multi-fidelity surrogate models represent the experimental data. This research compares three surrogates for the experimental data (sequential--a.k.a. online--Gaussian processes, batch Gaussian processes, and multi-fidelity additive corrector) on the merits of accuracy and computational cost. The Gaussian process (GP) methods employ cubic B-spline CFD surrogates as a model basis function to build a surrogate model of the WT data, and this usage of the CFD surrogate in building the WT