Abnormal pressures as hydrodynamic phenomena

USGS Publications Warehouse

Neuzil, C.E.

1995-01-01

So-called abnormal pressures, subsurface fluid pressures significantly higher or lower than hydrostatic, have excited speculation about their origin since subsurface exploration first encountered them. Two distinct conceptual models for abnormal pressures have gained currency among earth scientists. The static model sees abnormal pressures generally as relict features preserved by a virtual absence of fluid flow over geologic time. The hydrodynamic model instead envisions abnormal pressures as phenomena in which flow usually plays an important role. This paper develops the theoretical framework for abnormal pressures as hydrodynamic phenomena, shows that it explains the manifold occurrences of abnormal pressures, and examines the implications of this approach. -from Author

[THE ROLE OF PRESSURE ULCER SURROUNDING SKIN PREPARATION PRIOR TO THE APPLICATION OF WOUND DRESSING].

PubMed

Kulišić, S Marinović

2016-01-01

Pressure ulcer develops as a result of many factors, primarily pressure, tensile forces and ischemia with immobility and incontinence. Targeted and properly designed preventive measures reduce the incidence and complications of pressure ulcers, among which the most common are infections. An important preventive measure is protection of the surrounding skin before the application of wound dressings. Skin changes dictate the use of emollients and topical therapy according to dermatological status.

The Role of Maternal Dietary Proteins in Development of Metabolic Syndrome in Offspring

PubMed Central

Jahan-Mihan, Alireza; Rodriguez, Judith; Christie, Catherine; Sadeghi, Marjan; Zerbe, Tara

2015-01-01

The prevalence of metabolic syndrome and obesity has been increasing. Pre-natal environment has been suggested as a factor influencing the risk of metabolic syndrome in adulthood. Both observational and experimental studies showed that maternal diet is a major modifier of the development of regulatory systems in the offspring in utero and post-natally. Both protein content and source in maternal diet influence pre- and early post-natal development. High and low protein dams’ diets have detrimental effect on body weight, blood pressure191 and metabolic and intake regulatory systems in the offspring. Moreover, the role of the source of protein in a nutritionally adequate maternal diet in programming of food intake regulatory system, body weight, glucose metabolism and blood pressure in offspring is studied. However, underlying mechanisms are still elusive. The purpose of this review is to examine the current literature related to the role of proteins in maternal diets in development of characteristics of the metabolic syndrome in offspring. PMID:26561832

Educational and Career Expectations of Chinese-American College Students.

ERIC Educational Resources Information Center

Liu, Ruth Wang

1998-01-01

Interviews with second-generation Chinese-American undergraduates (N=30) revealed high self-imposed and perceived parental educational and career expectations. Suggests the powerful role of culture and parental pressure in the development of the inner drive for achievement. Parental support, as well as pressure, was reported. Discusses academic…

Development of Designer Diamond Technology for High Pressure High Temperature Experiments in Support of Stockpile Stewardship Program

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

Vohra, Yogesh, K.

The role of nitrogen in the fabrication of designer diamond was systematically investigated by adding controlled amount of nitrogen in hydrogen/methane/oxygen plasma. This has led to a successful recipe for reproducible fabrication of designer diamond anvils for high-pressure high-temperature research in support of stockpile stewardship program. In the three-year support period, several designer diamonds fabricated with this new growth chemistry were utilized in high-pressure experiments at UAB and Lawrence Livermore National Laboratory. The designer diamond anvils were utilized in high-pressure studies on heavy rare earth metals, high pressure melting studies on metals, and electrical resistance measurements on iron-based layered superconductorsmore » under high pressures. The growth chemistry developed under NNSA support can be adapted for commercial production of designer diamonds.« less

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-Induced Dissolution and Reentrant Formation of Condensed, Liquid-Liquid Phase-Separated Elastomeric α-Elastin.

PubMed

Cinar, Hasan; Cinar, Süleyman; Chan, Hue Sun; Winter, Roland

2018-05-08

We investigated the combined effects of temperature and pressure on liquid-liquid phase separation (LLPS) phenomena of α-elastin up to the multi-kbar regime. FT-IR spectroscopy, CD, UV/Vis absorption, phase-contrast light and fluorescence microscopy techniques were employed to reveal structural changes and mesoscopic phase states of the system. A novel pressure-induced reentrant LLPS was observed in the intermediate temperature range. A molecular-level picture, in particular on the role of hydrophobic interactions, hydration, and void volume in controlling LLPS phenomena is presented. The potential role of the LLPS phenomena in the development of early cellular compartmentalization is discussed, which might have started in the deep sea, where pressures up to the kbar level are encountered. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Cardiac contractile dysfunction during mild coronary flow reductions is due to an altered calcium-pressure relationship in rat hearts.

PubMed Central

Figueredo, V M; Brandes, R; Weiner, M W; Massie, B M; Camacho, S A

1992-01-01

Coronary artery stenosis or occlusion results in reduced coronary flow and myocardial contractile depression. At severe flow reductions, increased inorganic phosphate (Pi) and intracellular acidosis clearly play a role in contractile depression. However, during milder flow reductions the mechanism(s) underlying contractile depression are less clear. Previous perfused heart studies demonstrated no change of Pi or pH during mild flow reductions, suggesting that changes of intravascular pressure (garden hose effect) may be the mediator of this contractile depression. Others have reported conflicting results regarding another possible mediator of contractility, the cytosolic free calcium (Cai). To examine the respective roles of Cai, Pi, pH, and vascular pressure in regulating contractility during mild flow reductions, Indo-1 calcium fluorescence and 31P magnetic resonance spectroscopy measurements were performed on Langendorff-perfused rat hearts. Cai and diastolic calcium levels did not change during flow reductions to 50% of control. Pi demonstrated a close relationship with developed pressure and significantly increased from 2.5 +/- 0.3 to 4.2 +/- 0.4 mumol/g dry weight during a 25% flow reduction. pH was unchanged until a 50% flow reduction. Increasing vascular pressure to superphysiological levels resulted in further increases of developed pressure, with no change in Cai. These findings are consistent with the hypothesis that during mild coronary flow reductions, contractile depression is mediated by an altered relationship between Cai and pressure, rather than by decreased Cai. Furthermore, increased Pi and decreased intravascular pressure may be responsible for this altered calcium-pressure relationship during mild coronary flow reductions. PMID:1430205

Magnesium in hypertension, cardiovascular disease, metabolic syndrome, and other conditions: a review.

PubMed

Champagne, Catherine M

2008-01-01

Magnesium plays a role in a number of chronic, disease-related conditions. This article reviews current pertinent literature on magnesium, focusing on hypertension and cardiovascular diseases and implications for relationships with diabetes and metabolic syndrome. A major role for magnesium is in the regulation of blood pressure. While data are not entirely consistent, it does appear that an inverse relationship between magnesium intake and blood pressure is strongest for magnesium obtained from food rather than that obtained via supplements. Hypertension associated with preeclampsia appears to be alleviated when magnesium is administered; in addition, women with adequate intakes of magnesium are less likely to be affected by preeclampsia than those with an inadequate intake. A role for magnesium in other cardiovascular diseases has been noted in that increased magnesium intake may improve serum lipid profiles. Dietary magnesium is also recommended to aid in the prevention of stroke and is important for skeletal growth and development. Magnesium may also play a role in the development of diabetes mellitus, obesity, and metabolic syndrome. There are data from some studies, such as the DASH and PREMIER studies, that suggest that lifestyle changes (including adequate magnesium intake) can benefit blood pressure control, promote weight loss, and improve chronic disease risk.

Increased hydrostatic pressure enhances motility of lung cancer cells.

PubMed

Kao, Yu-Chiu; Lee, Chau-Hwang; Kuo, Po-Ling

2014-01-01

Interstitial fluid pressures within most solid tumors are significantly higher than that in the surrounding normal tissues. Therefore, cancer cells must proliferate and migrate under the influence of elevated hydrostatic pressure while a tumor grows. In this study, we developed a pressurized cell culture device and investigated the influence of hydrostatic pressure on the migration speeds of lung cancer cells (CL1-5 and A549). The migration speeds of lung cancer cells were increased by 50-60% under a 20 mmHg hydrostatic pressure. We also observed that the expressions of aquaporin in CL1-5 and A549 cells were increased under the hydrostatic pressure. Our preliminary results indicate that increased hydrostatic pressure plays an important role in tumor metastasis.

Resolving the Role of the Dynamic Pressure in the Burial, Exposure, Scour, and Mobility of Underwater Munitions

NASA Astrophysics Data System (ADS)

Gilooly, S.; Foster, D. L.

2017-12-01

In nearshore environments, the motion of munitions results from a mixture of sediment transport conditions including sheet flow, scour, bedform migration, and momentary liquefaction. Incipient motion can be caused by disruptive shear stresses and pressure gradients. Foster et al. (2006) incorporated both processes into a single parameter, indicating incipient motion as a function of the bed state. This research looks to evaluate the role of the pressure gradient in positional state changes such as burial, exposure, and mobility. In the case of munitions, this may include pressure gradients induced by vortex shedding or the passing wave. Pressure-mapped model munitions are being developed to measure the orientation, rotation, and surface pressure of the munitions during threshold events leading to a new positional state. These munitions will be deployed in inner surf zone and estuary environments along with acoustic Doppler velocimeters (ADVs), pore water pressure sensors, a laser grid, and a pencil beam sonar with an azimuth drive. The additional instruments allow for near bed and far field water column and sediment bed sampling. Currently preliminary assessments of various pressure sensors and munition designs are underway. Two pressure sensors were selected; the thin FlexiForce A201 sensors will be used to indicate munition rolling during threshold events and diaphragm sensors will be used to understand changes in surrounding pore water pressure as the munition begins to bury/unbury. Both sensors are expected to give quantitative measurements of dynamic pressure gradients in the flow field surrounding the munition. Resolving the role of this process will give insight to an improved incipient motion parameter and allow for better munition motion predictions.

Morphology Control of Multicomponent Polymeric Surfactants Using Pressure

NASA Astrophysics Data System (ADS)

Cho, Junhan

The development of nanoscale morphologies for a molten polymeric surfactant under pressure is investigated by using a recently formulated self-consistent field theory. A linear ABC block copolymer is taken as our model system that allows a disparity in the propensities for curved interfaces and pressure responses of ij-pairs. The interplay of those features lead the copolymer to new morphologies at a moderate segregation level and at ambient condition such as networks and pillars of 2-dimensional array. It is shown that pressure is an effective means of morphology control and identification for those new structures. The role of volume fluctuations in the development of those structures is discussed. J.C. acknowledges the support from Center for Photofunctional Energy Materials through Gyeonggi Regional Research Program.

The Role of Multimodal Invasive Monitoring in Acute Traumatic Brain Injury.

PubMed

Lazaridis, Christos; Robertson, Claudia S

2016-10-01

This article reviews the role of modalities that directly monitor brain parenchyma in patients with severe traumatic brain injury. The physiology monitored involves compartmental and perfusion pressures, tissue oxygenation and metabolism, quantitative blood flow, pressure autoregulation, and electrophysiology. There are several proposed roles for this multimodality monitoring, such as to track, prevent, and treat the cascade of secondary brain injury; monitor the neurologically injured patient; integrate various data into a composite, patient-specific, and dynamic picture; apply protocolized, pathophysiology-driven intensive care; use as a prognostic marker; and understand pathophysiologic mechanisms involved in secondary brain injury to develop preventive and abortive therapies, and to inform future clinical trials. Copyright © 2016 Elsevier Inc. All rights reserved.

Role of structural barriers for carotenoid bioaccessibility upon high pressure homogenization.

PubMed

Palmero, Paola; Panozzo, Agnese; Colle, Ines; Chigwedere, Claire; Hendrickx, Marc; Van Loey, Ann

2016-05-15

A specific approach to investigate the effect of high pressure homogenization on the carotenoid bioaccessibility in tomato-based products was developed. Six different tomato-based model systems were reconstituted in order to target the specific role of the natural structural barriers (chromoplast substructure/cell wall) and of the phases (soluble/insoluble) in determining the carotenoid bioaccessibility and viscosity changes upon high pressure homogenization. Results indicated that in the absence of natural structural barriers (carotenoid enriched oil), the soluble and insoluble phases determined the carotenoid bioaccessibility upon processing whereas, in their presence, these barriers governed the bioaccessibility. Furthermore, it was shown that the increment of the viscosity upon high pressure homogenization is determined by the presence of insoluble phase, however, this result was related to the initial ratio of the soluble:insoluble phases in the system. In addition, no relationship between the changes in viscosity and carotenoid bioaccessibility upon high pressure homogenization was found. Copyright © 2015 Elsevier Ltd. All rights reserved.

Comparison between gradient-dependent hydraulic conductivities of roots using the root pressure probe: the role of pressure propagations and implications for the relative roles of parallel radial pathways.

PubMed

Bramley, Helen; Turner, Neil C; Turner, David W; Tyerman, Stephen D

2007-07-01

Hydrostatic pressure relaxations with the root pressure probe are commonly used for measuring the hydraulic conductivity (Lp(r)) of roots. We compared the Lp(r) of roots from species with different root hydraulic properties (Lupinus angustifolius L. 'Merrit', Lupinus luteus L. 'Wodjil', Triticum aestivum L. 'Kulin' and Zea mays L. 'Pacific DK 477') using pressure relaxations, a pressure clamp and osmotic gradients to induce water flow across the root. Only the pressure clamp measures water flow under steady-state conditions. Lp(r) determined by pressure relaxations was two- to threefold greater than Lp(r) from pressure clamps and was independent of the direction of water flow. Lp(r) (pressure clamp) was two- to fourfold higher than for Lp(r) (osmotic) for all species except Triticum aestivum where Lp(r) (pressure clamp) and Lp(r) (osmotic) were not significantly different. A novel technique was developed to measure the propagation of pressure through roots to investigate the cause of the differences in Lp(r). Root segments were connected between two pressure probes so that when root pressure (P(r)) was manipulated by one probe, the other probe recorded changes in P(r). Pressure relaxations did not induce the expected kinetics in pressure in the probe at the other end of the root when axial hydraulic conductance, and probe and root capacitances were accounted for. An electric circuit model of the root was constructed that included an additional capacitance in the root loaded by a series of resistances. This accounted for the double exponential kinetics for intact roots in pressure relaxation experiments as well as the reduced response observed with the double probe experiments. Although there were potential errors with all the techniques, we considered that the measurement of Lp(r) using the pressure clamp was the most unambiguous for small pressure changes, and provided that sufficient time was allowed for pressure propagation through the root. The differences in Lp(r) from different methods of measurement have implications for the models describing water transport through roots and the potential role of aquaporins.

Endosperm turgor pressure decreases during early Arabidopsis seed development.

PubMed

Beauzamy, Léna; Fourquin, Chloé; Dubrulle, Nelly; Boursiac, Yann; Boudaoud, Arezki; Ingram, Gwyneth

2016-09-15

In Arabidopsis, rapid expansion of the coenocytic endosperm after fertilisation has been proposed to drive early seed growth, which is in turn constrained by the seed coat. This hypothesis implies physical heterogeneity between the endosperm and seed coat compartments during early seed development, which to date has not been demonstrated. Here, we combine tissue indentation with modelling to show that the physical properties of the developing seed are consistent with the hypothesis that elevated endosperm-derived turgor pressure drives early seed expansion. We provide evidence that whole-seed turgor is generated by the endosperm at early developmental stages. Furthermore, we show that endosperm cellularisation and seed growth arrest are associated with a drop in endosperm turgor pressure. Finally, we demonstrate that this decrease is perturbed when the function of POLYCOMB REPRESSIVE COMPLEX 2 is lost, suggesting that turgor pressure changes could be a target of genomic imprinting. Our results indicate a developmental role for changes in endosperm turgor pressure in the Arabidopsis seed. © 2016. Published by The Company of Biologists Ltd.

Pathways to Teacher Leadership: Emerging Models, Changing Roles

ERIC Educational Resources Information Center

Levenson, Marya R.

2014-01-01

"Pathways to Teacher Leadership" investigates emerging patterns in the development and effectiveness of teacher leadership.What roles do teachers pursue as they seek to lead change in their schools? What pressures and challenges do emerging leaders face? How can principals and peers support effective teacher leadership? Marya R. Levenson…

Acute lead exposure increases arterial pressure: role of the renin-angiotensin system.

PubMed

Simões, Maylla Ronacher; Ribeiro Júnior, Rogério F; Vescovi, Marcos Vinícius A; de Jesus, Honério C; Padilha, Alessandra S; Stefanon, Ivanita; Vassallo, Dalton V; Salaices, Mercedes; Fioresi, Mirian

2011-04-11

Chronic lead exposure causes hypertension and cardiovascular disease. Our purpose was to evaluate the effects of acute exposure to lead on arterial pressure and elucidate the early mechanisms involved in the development of lead-induced hypertension. Wistar rats were treated with lead acetate (i.v. bolus dose of 320 µg/Kg), and systolic arterial pressure, diastolic arterial pressure and heart rate were measured during 120 min. An increase in arterial pressure was found, and potential roles of the renin-angiotensin system, Na(+),K(+)-ATPase and the autonomic reflexes in this change in the increase of arterial pressure found were evaluated. In anesthetized rats, lead exposure: 1) produced blood lead levels of 37±1.7 µg/dL, which is below the reference blood concentration (60 µg/dL); 2) increased systolic arterial pressure (Ct: 109±3 mmHg vs Pb: 120±4 mmHg); 3) increased ACE activity (27% compared to Ct) and Na(+),K(+)-ATPase activity (125% compared to Ct); and 4) did not change the protein expression of the α1-subunit of Na(+),K(+)-ATPase, AT(1) and AT(2). Pre-treatment with an AT(1) receptor blocker (losartan, 10 mg/Kg) or an ACE inhibitor (enalapril, 5 mg/Kg) blocked the lead-induced increase of arterial pressure. However, a ganglionic blockade (hexamethonium, 20 mg/Kg) did not prevent lead's hypertensive effect. Acute exposure to lead below the reference blood concentration increases systolic arterial pressure by increasing angiotensin II levels due to ACE activation. These findings offer further evidence that acute exposure to lead can trigger early mechanisms of hypertension development and might be an environmental risk factor for cardiovascular disease.

Ozone kinetics in low-pressure discharges

NASA Astrophysics Data System (ADS)

Guerra, Vasco; Marinov, Daniil; Guaitella, Olivier; Rousseau, Antoine

2012-10-01

Ozone kinetics is quite well established at atmospheric pressure, due to the importance of ozone in atmospheric chemistry and to the development of industrial ozone reactors. However, as the pressure is decreased and the dominant three-body reactions lose importance, the main mechanisms involved in the creation and destruction of ozone are still surrounded by important uncertainties. In this work we develop a self-consistent model for a pulsed discharge and its afterglow operating in a Pyrex reactor with inner radius 1 cm, at pressures in the range 1-5 Torr and discharge currents of 40-120 mA. The model couples the electron Boltzmann equation with a system of equations for the time evolution of the heavy particles. The calculations are compared with time-dependent measurements of ozone and atomic oxygen. Parametric studies are performed in order to clarify the role of vibrationally excited ozone in the overall kinetics and to establish the conditions where ozone production on the surface may become important. It is shown that vibrationally excited ozone does play a significant role, by increasing the time constants of ozone formation. Moreover, an upper limit for the ozone formation at the wall in these conditions is set at 10(-4).

Serotonin and Blood Pressure Regulation

PubMed Central

Morrison, Shaun F.; Davis, Robert Patrick; Barman, Susan M.

2012-01-01

5-Hydroxytryptamine (5-HT; serotonin) was discovered more than 60 years ago as a substance isolated from blood. The neural effects of 5-HT have been well investigated and understood, thanks in part to the pharmacological tools available to dissect the serotonergic system and the development of the frequently prescribed selective serotonin-reuptake inhibitors. By contrast, our understanding of the role of 5-HT in the control and modification of blood pressure pales in comparison. Here we focus on the role of 5-HT in systemic blood pressure control. This review provides an in-depth study of the function and pharmacology of 5-HT in those tissues that can modify blood pressure (blood, vasculature, heart, adrenal gland, kidney, brain), with a focus on the autonomic nervous system that includes mechanisms of action and pharmacology of 5-HT within each system. We compare the change in blood pressure produced in different species by short- and long-term administration of 5-HT or selective serotonin receptor agonists. To further our understanding of the mechanisms through which 5-HT modifies blood pressure, we also describe the blood pressure effects of commonly used drugs that modify the actions of 5-HT. The pharmacology and physiological actions of 5-HT in modifying blood pressure are important, given its involvement in circulatory shock, orthostatic hypotension, serotonin syndrome and hypertension. PMID:22407614

Analyses of pressure ulcer incidence in inpatient setting in a Portuguese hospital.

PubMed

Sardo, Pedro Miguel Garcez; Simões, Cláudia Sofia Oliveira; Alvarelhão, José Joaquim Marques; Simões, João Filipe Fernandes Lindo; Machado, Paulo Alexandre Puga; Amado, Francisco Manuel Lemos; Amaro, António José Monteiro; Melo, Elsa Maria Oliveira Pinheiro de

2016-11-01

To gain more insight into the magnitude of the problem of pressure ulcer incidence in general wards of a Portuguese hospital. Retrospective cohort analysis of electronic health record database from 7132 adult patients admitted to medical and surgical wards of Aveiro Hospital during 2012. The development of (at least) one pressure ulcer during the length of stay was associated with age, gender, type of admission, specialty units, first Braden Scale score, length of stay, patient discharge outcome and ICD-9 diagnosis. An incidence of 3.4% participants with pressure ulcer category I-IV in inpatient setting during 2012. During the length of stay, 320 new pressure ulcers were developed, most of them category/stage II. The sacrum/coccyx and the trochanters were the most problematic areas. The major risk factor for the development of a new pressure ulcer during the length of stay was the presence of (at least) one pressure ulcer at the first skin assessment. The length of stay itself, age and lower Braden Scale scores of our participants also played an important role in the odds of developing a pressure ulcer. Infectious diseases, traumatism and fractures and respiratory diseases were the ICD-9 diagnoses with higher frequency of participants that developed (at least) one pressure ulcer during the length of stay. It's important to standardize procedures and documentation in all care settings. The documentation of nursing interventions is vital to evaluate the impact of evidence-based nursing. Copyright © 2016 Tissue Viability Society. Published by Elsevier Ltd. All rights reserved.

The Crucial Role of Recess in Schools

ERIC Educational Resources Information Center

Ramstetter, Catherine L.; Murray, Robert; Garner, Andrew S.

2010-01-01

Background: Recess is at the heart of a vigorous debate over the role of schools in promoting optimal child development and well-being. Reallocating time to accentuate academic concerns is a growing trend and has put recess at risk. Conversely, pressure to increase activity in school has come from efforts to combat childhood obesity. The purpose…

p38α Mitogen-Activated Protein Kinase Plays a Critical Role in Cardiomyocyte Survival but Not in Cardiac Hypertrophic Growth in Response to Pressure Overload

PubMed Central

Nishida, Kazuhiko; Yamaguchi, Osamu; Hirotani, Shinichi; Hikoso, Shungo; Higuchi, Yoshiharu; Watanabe, Tetsuya; Takeda, Toshihiro; Osuka, Soh; Morita, Takashi; Kondoh, Gen; Uno, Yoshihiro; Kashiwase, Kazunori; Taniike, Masayuki; Nakai, Atsuko; Matsumura, Yasushi; Miyazaki, Jun-ichi; Sudo, Tatsuhiko; Hongo, Kenichi; Kusakari, Yoichiro; Kurihara, Satoshi; Chien, Kenneth R.; Takeda, Junji; Hori, Masatsugu; Otsu, Kinya

2004-01-01

The molecular mechanism for the transition from cardiac hypertrophy, an adaptive response to biomechanical stress, to heart failure is poorly understood. The mitogen-activated protein kinase p38α is a key component of stress response pathways in various types of cells. In this study, we attempted to explore the in vivo physiological functions of p38α in hearts. First, we generated mice with floxed p38α alleles and crossbred them with mice expressing the Cre recombinase under the control of the α-myosin heavy-chain promoter to obtain cardiac-specific p38α knockout mice. These cardiac-specific p38α knockout mice were born normally, developed to adulthood, were fertile, exhibited a normal life span, and displayed normal global cardiac structure and function. In response to pressure overload to the left ventricle, they developed significant levels of cardiac hypertrophy, as seen in controls, but also developed cardiac dysfunction and heart dilatation. This abnormal response to pressure overload was accompanied by massive cardiac fibrosis and the appearance of apoptotic cardiomyocytes. These results demonstrate that p38α plays a critical role in the cardiomyocyte survival pathway in response to pressure overload, while cardiac hypertrophic growth is unaffected despite its dramatic down-regulation. PMID:15572667

Use of home blood-pressure monitoring in the detection, treatment and surveillance of hypertension.

PubMed

Manning, Gillian; Donnelly, Richard

2005-11-01

Use of home blood-pressure monitoring is increasing but the technique and the equipment have limitations. We provide an overview of recent evidence in this rapidly evolving field. Home blood-pressure monitoring is an acceptable method for screening patients for hypertension. There is increasing evidence supporting the predictive power of home blood pressure for stroke risk even in the general population. The identification of white-coat and masked hypertension remains an important role for home blood-pressure monitoring. Unvalidated equipment and poor patient technique are major concerns. The purchase of devices needs to be linked to a simple patient-education programme, which is perhaps an opportunity for collaboration between healthcare providers and commercial companies. Devices that store the blood-pressure measurements in the memory are preferred to ensure accuracy of reporting. Data-transmission systems providing automatic storage, transmission and reporting of blood pressure, direct involvement of the patient and potentially a reduced number of hospital/general practitioner visits, offer significant advantages. To reduce patient anxiety, overuse of home blood-pressure monitoring should be avoided but there is the potential for self-modification of treatment, subject to certain safeguards. Self-monitoring of blood pressure is developing rapidly, linked to increasing awareness of the impact of reducing high blood pressure on public health and the marketing/advertising strategies used to sell automatic devices. Home blood-pressure monitoring has a role in the detection and management of blood pressure, but not at the expense of careful blood-pressure measurement in the office and adherence to national guidelines.

Alternative thermodynamic cycle for the Stirling machine

NASA Astrophysics Data System (ADS)

Romanelli, Alejandro

2017-12-01

We develop an alternative thermodynamic cycle for the Stirling machine, where the polytropic process plays a central role. Analytical expressions for pressure and temperatures of the working gas are obtained as a function of the volume and the parameter that characterizes the polytropic process. This approach achieves closer agreement with the experimental pressure-volume diagram and can be adapted to any type of Stirling engine.

Modeling of Aerosols in Post-Combustor Flow Path and Sampling System

NASA Technical Reports Server (NTRS)

Wey, Thomas; Liu, Nan-Suey

2006-01-01

The development and application of a multi-dimensional capability for modeling and simulation of aviation-sourced particle emissions and their precursors are elucidated. Current focus is on the role of the flow and thermal environments. The cases investigated include a film cooled turbine blade, the first-stage of a high-pressure turbine, the sampling probes, the sampling lines, and a pressure reduction chamber.

The Seasons of Competency Development for Women.

ERIC Educational Resources Information Center

Loeffler, T. A.

2000-01-01

Discusses stages of competency development, using the seasons of the year as a metaphor. Identifies educational strategies that outdoor educators can use at each stage to help women overcome gender role socialization pressures that discourage them from achieving or recognizing their true competency levels. (TD)

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.

Theory of acoustic radiation pressure for actual fluids

NASA Astrophysics Data System (ADS)

Doinikov, Alexander A.

1996-12-01

A body irradiated by a sound field is known to experience a steady force that is called the acoustic radiation pressure. This force plays an important role in many physical phenomena, such as cavitation, sonoluminescence, acoustic levitation, etc. The existing theory of acoustic radiation pressure neglects dissipative effects. The present paper develops a theory that takes these effects into account, both dissipative mechanisms, viscous and thermal, being considered. It is shown that, when they are no longer negligible, the dissipative effects drastically change the radiation pressure. As a result, its magnitude and sign become different from those predicted by the ``classical'' theory neglecting losses.

Integrated electrofluidic circuits: pressure sensing with analog and digital operation functionalities for microfluidics.

PubMed

Wu, Chueh-Yu; Lu, Jau-Ching; Liu, Man-Chi; Tung, Yi-Chung

2012-10-21

Microfluidic technology plays an essential role in various lab on a chip devices due to its desired advantages. An automated microfluidic system integrated with actuators and sensors can further achieve better controllability. A number of microfluidic actuation schemes have been well developed. In contrast, most of the existing sensing methods still heavily rely on optical observations and external transducers, which have drawbacks including: costly instrumentation, professional operation, tedious interfacing, and difficulties of scaling up and further signal processing. This paper reports the concept of electrofluidic circuits - electrical circuits which are constructed using ionic liquid (IL)-filled fluidic channels. The developed electrofluidic circuits can be fabricated using a well-developed multi-layer soft lithography (MSL) process with polydimethylsiloxane (PDMS) microfluidic channels. Electrofluidic circuits allow seamless integration of pressure sensors with analog and digital operation functions into microfluidic systems and provide electrical readouts for further signal processing. In the experiments, the analog operation device is constructed based on electrofluidic Wheatstone bridge circuits with electrical outputs of the addition and subtraction results of the applied pressures. The digital operation (AND, OR, and XOR) devices are constructed using the electrofluidic pressure controlled switches, and output electrical signals of digital operations of the applied pressures. The experimental results demonstrate the designed functions for analog and digital operations of applied pressures are successfully achieved using the developed electrofluidic circuits, making them promising to develop integrated microfluidic systems with capabilities of precise pressure monitoring and further feedback control for advanced lab on a chip applications.

Oxygen Partial Pressure and Oxygen Concentration Flammability: Can They Be Correlated?

NASA Technical Reports Server (NTRS)

Harper, Susana A.; Juarez, Alfredo; Perez, Horacio, III; Hirsch, David B.; Beeson, Harold D.

2016-01-01

NASA possesses a large quantity of flammability data performed in ISS airlock (30% Oxygen 526mmHg) and ISS cabin (24.1% Oxygen 760 mmHg) conditions. As new programs develop, other oxygen and pressure conditions emerge. In an effort to apply existing data, the question arises: Do equivalent oxygen partial pressures perform similarly with respect to flammability? This paper evaluates how material flammability performance is impacted from both the Maximum Oxygen Concentration (MOC) and Maximum Total Pressures (MTP) perspectives. From these studies, oxygen partial pressures can be compared for both the MOC and MTP methods to determine the role of partial pressure in material flammability. This evaluation also assesses the influence of other variables on flammability performance. The findings presented in this paper suggest flammability is more dependent on oxygen concentration than equivalent partial pressure.

Organisational Culture and Its Role in Developing a Sustainable Science Communication Platform

ERIC Educational Resources Information Center

France, Bev; Cridge, Belinda; Fogg-Rogers, Laura

2017-01-01

There is an ongoing tension for scientists when deciding to engage with the public about their research as many scientists view direct participation as peripheral to their role. Pressures of time, lack of support by management and a lack of communicative skills are identified by scientists as reasons for not committing to communicative…

Atrial fibrillation and arterial hypertension: A common duet with dangerous consequences where the renin angiotensin-aldosterone system plays an important role.

PubMed

Seccia, Teresa Maria; Caroccia, Brasilina; Muiesan, Maria Lorenza; Rossi, Gian Paolo

2016-03-01

Atrial fibrillation (AF) represents the most common sustained cardiac arrhythmia, as it affects 1%-2% of the general population and up to 15% of people over 80 years. High blood pressure, due to its high prevalence in the general population, is by far the most common condition associated with AF, although a variety of diseases, including valvular, coronary heart and metabolic diseases, are held to create the substrate favouring AF. Due to the concomitance of these conditions, it is quite challenging to dissect the precise role of high blood pressure in triggering/causing AF. Hence, even though the intimate association between high blood pressure and AF has been known for decades, the underlying mechanisms remain partially unknown. Accumulating evidences point to a major role of the renin-angiotensin-aldosterone system in inducing cardiac inflammation and fibrosis, and therefore electric and structural atrial and ventricular remodelling, with changes in ions and cell junctions leading to AF development. These evidences are herein reviewed with a particular emphasis to the role of the renin-angiotensin-system aldosterone system. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Nurse Managers' prerequisite for nursing development: a survey on pressure ulcers and contextual factors in hospital organizations.

PubMed

Gunningberg, Lena; Brudin, Lars; Idvall, Ewa

2010-09-01

To describe and compare pressure ulcer prevalence in two county councils and concurrently explore Nurse Managers' perspective of contextual factors in a hospital organization. Despite good knowledge about risk factors and prevention of pressure ulcers, the prevalence of pressure ulcers remains high. Nurse Managers' have a key role in implementing evidence-based practice. The present study included five hospitals in two Swedish county councils: county council A (non-university setting) and county council B (university setting). A pressure ulcer prevalence study was conducted according to the methodology developed by the European Pressure Ulcer Advisory Panel. The Nurse Managers' answered a (27-item) questionnaire on contextual factors. County council B had significantly less pressure ulcers grade (2-4) (7.7%) than county council A (11.3%). The Nurse Managers' assessed only two out of the 27 general contextual items significantly differently. Some significant differences were observed in ward organization. In county council B, the Nurse Managers' seemed more aware of prevention strategies compared with Nurse Managers' in county council A. The Nurse Managers' should take more responsibility to develop the prerequisite for quality improvement in nursing. Nursing outcomes (e.g. pressure ulcers) should be incorporated into national quality registries for benchmarking and Nurse Managers' competence in evidence-based practice and research methodology increased. © 2010 The Authors. Journal compilation © 2010 Blackwell Publishing Ltd.

Ablation of biglycan attenuates cardiac hypertrophy and fibrosis after left ventricular pressure overload.

PubMed

Beetz, Nadine; Rommel, Carolin; Schnick, Tilman; Neumann, Elena; Lother, Achim; Monroy-Ordonez, Elsa Beatriz; Zeeb, Martin; Preissl, Sebastian; Gilsbach, Ralf; Melchior-Becker, Ariane; Rylski, Bartosz; Stoll, Monika; Schaefer, Liliana; Beyersdorf, Friedhelm; Stiller, Brigitte; Hein, Lutz

2016-12-01

Biglycan, a small leucine-rich proteoglycan, has been shown to play an important role in stabilizing fibrotic scars after experimental myocardial infarction. However, the role of biglycan in the development and regression of cardiomyocyte hypertrophy and fibrosis during cardiac pressure overload and unloading remains elusive. Thus, the aim of the present study was to assess the effect of biglycan on cardiac remodeling in a mouse model of left ventricular pressure overload and unloading. Left ventricular pressure overload induced by transverse aortic constriction (TAC) in mice resulted in left ventricular dysfunction, fibrosis and increased biglycan expression. Fluorescence- and magnetic-assisted sorting of cardiac cell types revealed upregulation of biglycan in the fibroblast population, but not in cardiomyocytes, endothelial cells or leukocytes after TAC. Removal of the aortic constriction (rTAC) after short-term pressure overload (3weeks) improved cardiac contractility and reversed ventricular hypertrophy but not fibrosis in wild-type (WT) mice. Biglycan ablation (KO) enhanced functional recovery but did not resolve cardiac fibrosis. After long-term TAC for 9weeks, ablation of biglycan attenuated the development of cardiac hypertrophy and fibrosis. In vitro, biglycan induced hypertrophy of neonatal rat cardiomyocytes and led to activation of a hypertrophic gene program. Putative downstream mediators of biglycan signaling include Rcan1, Abra and Tnfrsf12a. These genes were concordantly induced by TAC in WT but not in biglycan KO mice. Left ventricular pressure overload induces biglycan expression in cardiac fibroblasts. Ablation of biglycan improves cardiac function and attenuates left ventricular hypertrophy and fibrosis after long-term pressure overload. In vitro biglycan induces hypertrophy of cardiomyocytes, suggesting that biglycan may act as a signaling molecule between cell types to modulate cardiac remodeling. Copyright © 2016 Elsevier Ltd. All rights reserved.

Market Pressure and Government Intervention in the Administration and Development of Molecular Databases.

ERIC Educational Resources Information Center

Sillince, J. A. A.; Sillince, M.

1993-01-01

Discusses molecular databases and the role that government and private companies play in their administration and development. Highlights include copyright and patent issues relating to public databases and the information contained in them; data quality; data structures and technological questions; the international organization of molecular…

Barriers to Community Participation in Development Planning: Lessons from the Mutengene (Cameroon) Self-Help Water Project.

ERIC Educational Resources Information Center

Njoh, Ambe J.

2002-01-01

A community water supply project in Cameroon illustrates the following constraints on community participation in development: paternalistic authorities, prescriptive role of the state, selective participation, bias toward "hard" issues, inattention to negative results, group conflicts, gatekeeping, pressure for immediate results,…

Constructing Knowledge: The Case of Leisure Management in the UK

ERIC Educational Resources Information Center

Pitchford, Andy; Bacon, William

2005-01-01

Models of curricula development in higher education pay scant attention to the role of self-interested actors in the construction of knowledge. Rather, it is assumed that curricula develop on the basis of fission within disciplines, fusion between fields, the exertion of pressure by the state or other stakeholders, or the development of knowledge…

Urinary Angiotensinogen Excretion Level Is Associated With Elevated Blood Pressure in the Normotensive General Population.

PubMed

Sato, Emiko; Wang, An Yi; Satoh, Michihiro; Nishikiori, Yoko; Oba-Yabana, Ikuko; Yoshida, Mai; Sato, Hiroshi; Ito, Sadayoshi; Hida, Wataru; Mori, Takefumi

2018-05-07

Inflammation, intrarenal renin-angiotensin system (RAS) activation, oxidative stress, and carbonyl stress have been postulated to play a fundamental role in controlling blood pressure. However, little is known about the association among renal RAS activation, carbonyl stress, and blood pressure elevation. We evaluated the relationship between blood pressure elevation and either renal RAS activity or carbonyl stress in the general population (N = 355) in Japan. To minimize the effect of antihypertensive drug therapy, we divided participants into 3 groups (normotensive, hypertensive-with-non-medication, and hypertensive-with-medication). Intrarenal RAS activity and carbonyl stress were indicated by the urinary angiotensinogen (AGT) and carbonyl compound excretion levels, respectively. The urinary AGT and carbonyl compound excretion levels were significantly associated with blood pressure. Using a stepwise multiple regression analysis, we found that the urinary AGT excretion levels were strongly associated with blood pressure elevation, compared with inflammation, oxidative stress, and carbonyl stress markers, in all groups. Urinary carbonyl compound excretion was significantly associated with blood pressure in only the hypertensive-without-medication group. Furthermore, blood pressure was significantly increased in these participants, and both the urinary AGT and carbonyl compound levels were high. The urinary AGT excretion levels were strongly associated with elevated blood pressure in normotensive people, and inappropriate renal RAS activity and carbonyl stress independently contributed to the development of hypertension. These findings suggest that RAS activation, particularly renal RAS activation exert a fundamental role in the pathogenesis of hypertension in the general population.

Deep Tissue Injury in Development of Pressure Ulcers: A Decrease of Inflammasome Activation and Changes in Human Skin Morphology in Response to Aging and Mechanical Load

PubMed Central

Stojadinovic, Olivera; Minkiewicz, Julia; Sawaya, Andrew; Bourne, Jonathan W.; Torzilli, Peter; de Rivero Vaccari, Juan Pablo; Dietrich, W. Dalton; Keane, Robert W.; Tomic-Canic, Marjana

2013-01-01

Molecular mechanisms leading to pressure ulcer development are scarce in spite of high mortality of patients. Development of pressure ulcers that is initially observed as deep tissue injury is multifactorial. We postulate that biomechanical forces and inflammasome activation, together with ischemia and aging, may play a role in pressure ulcer development. To test this we used a newly-developed bio-mechanical model in which ischemic young and aged human skin was subjected to a constant physiological compressive stress (load) of 300 kPa (determined by pressure plate analyses of a person in a reclining position) for 0.5–4 hours. Collagen orientation was assessed using polarized light, whereas inflammasome proteins were quantified by immunoblotting. Loaded skin showed marked changes in morphology and NLRP3 inflammasome protein expression. Sub-epidermal separations and altered orientation of collagen fibers were observed in aged skin at earlier time points. Aged skin showed significant decreases in the levels of NLRP3 inflammasome proteins. Loading did not alter NLRP3 inflammasome proteins expression in aged skin, whereas it significantly increased their levels in young skin. We conclude that aging contributes to rapid morphological changes and decrease in inflammasome proteins in response to tissue damage, suggesting that a decline in the innate inflammatory response in elderly skin could contribute to pressure ulcer pathogenesis. Observed morphological changes suggest that tissue damage upon loading may not be entirely preventable. Furthermore, newly developed model described here may be very useful in understanding the mechanisms of deep tissue injury that may lead towards development of pressure ulcers. PMID:23967056

Development of Kinetics and Mathematical Models for High Pressure Gasification of Lignite-Switchgrass Blends

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

Agrawal, Pradeep K.

The overall objective of the current project was to investigate the high pressure gasification characteristics of a feed containing both coal and biomass. The two feed types differ in their ash contents and ash composition, particularly the alkali content. Gasification of a combined feed of coal and biomass has the potential for considerable synergies that might lead to a dramatic improvement in process economics and flexibility. The proposed study aimed to develop a detailed understanding of the chemistry, kinetics, and transport effects during high pressure gasification of coal-biomass blend feed. Specifically, we studied to develop: (a) an understanding of themore » catalytic effect of alkali and other inorganic species present in the biomass and coal, (b) an understanding of processing conditions under which synergistic effects of the blending of coal and biomass might be observed. This included the role of particle size, residence time, and proximity of the two feed types, (c) kinetics of high pressure gasification of individual feeds as well as the blends, and (d) development of mathematical models that incorporate kinetics and transport models to enable prediction of gasification rate at a given set of operating conditions, and (e) protocols to extend the results to other feed resources. The goal was to provide a fundamental understanding of the gasification process and guide in optimizing the configurations and design of the next generation of gasifiers. The approach undertaken was centered on two basic premises: (1) the gasification for small particles without internal mass transfer limitations can be treated as the sum of two processes in series (pyrolysis and char gasification) , and (2) the reactivity of the char generated during pyrolysis not only depends on the pressure and temperature but is also affected by the heating rates. Thus low heating rates (10-50 °C/min) typical of PTGA fail to produce char that would typically be formed at high heating rates (~10 4 °C/sec), encountered in entrained flow gasifiers. The char morphology, also a function of the heating rate, would influence the transport rates during the char gasification phase. Thus, heating rate plays a critical role through which both, pyrolysis and char gasification, are interconnected. We utilized two complementary gasification experiments: PEFR (pressurized entrained flow gasifier) and PTGA (pressurized thermo-gravimetric analyzer). The PEFR allowed us to study gasification at pressures, temperatures, and heating rates relevant for coal-biomass gasifiers. The PTGA work was useful in understanding the basic chemistry of the evolution of various gaseous species during pyrolysis. These results helped improved our understanding of the chemistry and chemical changes during pyrolysis. The role alkali metals and other inorganics in char gasification using steam and/or CO 2 was investigated. Finally, the mathematical models for char gasification without the transport effects were developed at commercial operating conditions.« less

Betweenness-Based Method to Identify Critical Transmission Sectors for Supply Chain Environmental Pressure Mitigation.

PubMed

Liang, Sai; Qu, Shen; Xu, Ming

2016-02-02

To develop industry-specific policies for mitigating environmental pressures, previous studies primarily focus on identifying sectors that directly generate large amounts of environmental pressures (a.k.a. production-based method) or indirectly drive large amounts of environmental pressures through supply chains (e.g., consumption-based method). In addition to those sectors as important environmental pressure producers or drivers, there exist sectors that are also important to environmental pressure mitigation as transmission centers. Economy-wide environmental pressure mitigation might be achieved by improving production efficiency of these key transmission sectors, that is, using less upstream inputs to produce unitary output. We develop a betweenness-based method to measure the importance of transmission sectors, borrowing the betweenness concept from network analysis. We quantify the betweenness of sectors by examining supply chain paths extracted from structural path analysis that pass through a particular sector. We take China as an example and find that those critical transmission sectors identified by betweenness-based method are not always identifiable by existing methods. This indicates that betweenness-based method can provide additional insights that cannot be obtained with existing methods on the roles individual sectors play in generating economy-wide environmental pressures. Betweenness-based method proposed here can therefore complement existing methods for guiding sector-level environmental pressure mitigation strategies.

Role of atrial endothelial cells in the development of atrial fibrosis and fibrillation in response to pressure overload.

PubMed

Kume, Osamu; Teshima, Yasushi; Abe, Ichitaro; Ikebe, Yuki; Oniki, Takahiro; Kondo, Hidekazu; Saito, Shotaro; Fukui, Akira; Yufu, Kunio; Miura, Masahiro; Shimada, Tatsuo; Takahashi, Naohiko

Monocyte chemoattractant protein-1 (MCP-1)-mediated inflammatory mechanisms have been shown to play a crucial role in atrial fibrosis induced by pressure overload. In the present study, we investigated whether left atrial endothelial cells would quickly respond structurally and functionally to pressure overload to trigger atrial fibrosis and fibrillation. Six-week-old male Sprague-Dawley rats underwent suprarenal abdominal aortic constriction (AAC) or a sham operation. By day 3 after surgery, macrophages were observed to infiltrate into the endocardium. The expression of MCP-1 and E-selectin in atrial endothelium and the expression of intercellular adhesion molecule-1, vascular cell adhesion molecule-1, and ED1 in left atrial tissue were enhanced. Atrial endothelial cells were irregularly hypertrophied with the disarrangement of lines of cells by scanning electron microscopy. Various-sized gap formations appeared along the border in atrial endothelial cells, and several macrophages were located just in the endothelial gap. Along with the development of heterogeneous interstitial fibrosis, interatrial conduction time was prolonged and the inducibility of atrial fibrillation by programmed extrastimuli was increased in the AAC rats compared to the sham-operated rats. Atrial endothelium responds rapidly to pressure overload by expressing adhesion molecules and MCP-1, which induce macrophage infiltration into the atrial tissues. These processes could be an initial step in the development of atrial remodeling for atrial fibrillation. Copyright © 2016 Elsevier Inc. All rights reserved.

Nursing Education in High Blood Pressure Control. Report of the Task Force on the Role of Nursing in High Blood Pressure Control.

ERIC Educational Resources Information Center

National Institutes of Health (DHEW), Bethesda, MD. High Blood Pressure Information Center.

This curriculum guide on high blood pressure (hypertension) for nursing educators has five sections: (1) Introduction and Objectives provides information regarding the establishment and objectives of the National Task Force on the Role of Nursing in High Blood Pressure Control and briefly discusses nursing's role in hypertension control; (2) Goals…

Improving understanding of trigger points and widespread pressure pain sensitivity in tension-type headache patients: clinical implications.

PubMed

Fernández-De-Las-Peñas, César; Arendt-Nielsen, Lars

2017-09-01

The underlying etiology of tension type headache (TTH) is not understood. The current paper highlights the etiologic role of muscle trigger points (TrPs) to the development and maintenance of central sensitization in TTH and its clinical repercussion for proper management of these patients. Areas covered: A literature search on Pub Med for English-language published papers between 1990 and May 2017 to provide the most updated data on the topic was conducted. Current literature suggests that the referred pain elicited by active trigger points (TrPs) contributes to the manifestations of TTH. There is also evidence supporting that TrPs represent a peripheral source of nociception and thereby a driver in the development of central sensitization. In fact, TrPs have been found to be associated with widespread pressure pain sensitivity in TTH. Temporal and spatial summation of TrP nociception suggests that inactivating TrP in the neck, head and shoulder muscles could help these patients; however, current evidence supporting the therapeutic role of TrPs in TTH is conflicting. Expert commentary: Understanding the role of TrPs in TTH in widespread pain sensitization may help to develop better management regimes and possibly prevent TTH from developing into more chronic conditions.

What role can nurse leaders play in reducing the incidence of pressure sores?

PubMed

Wurster, Joan

2007-01-01

Pressure sores have plagued the nursing profession for many years as a major health care problem in terms of a patient's suffering and financial cost. Pressure sores are increasingly common in hospitalized patients in the United States with a 63% increase from 1993 to 2003. The nurse leader is accountable for the occurrence of pressure sores, a nurse-sensitive indicator, by a scorecard which is benchmarked against other facilities. The nurse leader must take a systematic approach in the prevention of pressure sores, with the strategy being consistent and motivating to the staff in order to improve patient outcome. The chief nursing officer, the unit manager, and the bedside nurse must all collaborate to prevent tissue injury in patients at risk for developing pressure sores and to promote wound healing in patients with existing breakdown.

Peer pressure and incentive mechanisms in social networks

NASA Astrophysics Data System (ADS)

Deng, Chuang; Ye, Chao; Wang, Lin; Rong, Zhihai; Wang, Xiaofan

2018-01-01

Cooperation can be viewed as a social norm that is expected in our society. In this work, a framework based on spatial public goods game theory is established to study how peer pressure and incentive mechanisms can influence the evolution of cooperation. A unified model with adjustable parameters is developed to represent the effects of pure Personal Mechanism, Personal Mechanism with peer pressure and Social Mechanism, which demonstrates that when the sum of rewards plus the peer pressure felt by defectors is larger than the effective cost of cooperation, cooperation can prevail. As the peer pressure is caused by other cooperators in a game, group size and network structure play an important role. In particular, larger group size and more heterogeneous structured population can make defectors feel more peer pressure, which will promote the evolution and sustainment of cooperation.

IRAK4 deficiency promotes cardiac remodeling induced by pressure overload

PubMed Central

Yuan, Yuan; Gan, Huawen; Dai, Jia; Zhou, Heng; Deng, Wei; Zong, Jing; Bian, Zhouyan; Liao, Haihan; Li, Hongliang; Tang, Qizhu

2015-01-01

Background: Interluekin1 receptor-associated kinase-4 (IRAK4) plays an essential role in the innate immune system. The aim of this study was to investigate the role of IRAK4 in cardiac remodeling induced by pressure overload and elucidate the underlying mechanisms. Methods: In vivo studies were performed using IRAK4 heterozygous knockout (HET) mice and wild type (WT) mice. Models of cardiac remodeling were induced by aortic banding (AB). Cardiac remodeling was evaluated by Echocardiography and histological analysis. Results: IRAK4 was upregulated in hearts of dilated cardiomyopathy (DCM) patients and also pressure overload-induced mice hearts. IRAK4 HET mice exhibited exacerbated cardiac hypertrophy, dysfunction and fibrosis after 4 weeks of AB compared with that in WT mice. Furthermore, enhanced activation of the MEK-ERK1/2, p38 and NFκB pathways was found in IRAK4 HET mice compared to WT mice. Conclusion: Our results suggest that IRAK4 may play a crucial role in the development of cardiac remodeling via negative regulation of multiple signaling pathways. PMID:26884959

Loss of Akap1 Exacerbates Pressure Overload-Induced Cardiac Hypertrophy and Heart Failure.

PubMed

Schiattarella, Gabriele G; Boccella, Nicola; Paolillo, Roberta; Cattaneo, Fabio; Trimarco, Valentina; Franzone, Anna; D'Apice, Stefania; Giugliano, Giuseppe; Rinaldi, Laura; Borzacchiello, Domenica; Gentile, Alessandra; Lombardi, Assunta; Feliciello, Antonio; Esposito, Giovanni; Perrino, Cinzia

2018-01-01

Left ventricular hypertrophy (LVH) is a major contributor to the development of heart failure (HF). Alterations in cyclic adenosine monophosphate (cAMP)-dependent signaling pathways participate in cardiomyocyte hypertrophy and mitochondrial dysfunction occurring in LVH and HF. cAMP signals are received and integrated by a family of cAMP-dependent protein kinase A (PKA) anchor proteins (AKAPs), tethering PKA to discrete cellular locations. AKAPs encoded by the Akap1 gene (mitoAKAPs) promote PKA mitochondrial targeting, regulating mitochondrial structure and function, reactive oxygen species production, and cell survival. To determine the role of mitoAKAPs in LVH development, in the present investigation, mice with global genetic deletion of Akap1 ( Akap1 -/- ), Akap1 heterozygous ( Akap1 +/- ), and their wild-type ( wt ) littermates underwent transverse aortic constriction (TAC) or SHAM procedure for 1 week. In wt mice, pressure overload induced the downregulation of AKAP121, the major cardiac mitoAKAP. Compared to wt, Akap1 -/- mice did not display basal alterations in cardiac structure or function and cardiomyocyte size or fibrosis. However, loss of Akap1 exacerbated LVH and cardiomyocyte hypertrophy induced by pressure overload and accelerated the progression toward HF in TAC mice, and these changes were not observed upon prevention of AKAP121 degradation in seven in absentia homolog 2 ( Siah2 ) knockout mice ( Siah2 -/- ). Loss of Akap1 was also associated to a significant increase in cardiac apoptosis as well as lack of activation of Akt signaling after pressure overload. Taken together, these results demonstrate that in vivo genetic deletion of Akap1 enhances LVH development and accelerates pressure overload-induced cardiac dysfunction, pointing at Akap1 as a novel repressor of pathological LVH. These results confirm and extend the important role of mitoAKAPs in cardiac response to stress.

The role of dressings in the prevention of pressure ulcers.

PubMed

Brown, Julie

2016-08-11

Pressure ulceration is a significant global healthcare problem and represents a considerable burden on healthcare resources. Within the literature an increasing number of studies have examined the role prophylactic dressings play in redistributing pressure and helping to protect the skin from the effects of friction and shear. The use of dressings to prevent pressure ulcers may be considered a controversial issue, as previous opinion has been that dressings do not reduce the effects of pressure. This article will critically evaluate the literature to examine the role dressings play in the prevention of pressure ulceration.

Role of ischemic modified albumin in the early diagnosis of increased intracranial pressure and brain death.

PubMed

Kara, I; Pampal, H K; Yildirim, F; Dilekoz, E; Emmez, G; U, F P; Kocabiyik, M; Demirel, C B

Increased intracranial pressure following trauma and subsequent possible development of brain death are important factors for morbidity and mortality due to ischemic changes. We aimed to establish the role of ischemic modified albumin (IMA) in the early diagnosis of the process, starting with increased intracranial pressure and ending with brain death. Eighteen Wistar-Albino rats were divided into three groups; control (CG, n = 6), increased intracranial pressure (ICPG, n = 6), and brain death (BDG, n = 6). Intracranial pressure elevation and brain death were constituted with the inflation of a balloon of a Fogarty catheter in the epidural space. In all three groups, blood samples were drawn before the procedure, and at minutes 150 and 240 for IMA and malondialdehyde (MDA) analysis. Serum IMA levels at 150 and 240 minutes were higher in ICPG than in CG (p < 0.05). IMA levels were similar in ICPG and BDG. Serum MDA levels at 150 and 240 minutes increased in ICPG and BDG groups compared to CG (p < 0.05). MDA levels were similar in ICP and BD groups. IMA should be considered as a biochemical parameter in the process starting from increased intracranial pressure elevation and ending at brain death (Tab. 3, Fig. 5, Ref. 31).

The Environment and Blood Pressure.

PubMed

Brook, Robert D

2017-05-01

A host of environmental factors can significantly increase arterial blood pressure (BP) including cold temperature, high altitude, loud noises, and ambient air pollutants. Although brief exposures acutely elevate BP, over the long term, chronic exposures may be capable of promoting the development of sustained hypertension. Given their omnipresent nature, environmental factors may play a role in worsening BP control and heightening overall cardiovascular risk at the global public health level. Copyright © 2016 Elsevier Inc. All rights reserved.

Control of Acoustics and Store Separation in a Cavity in Supersonic Flow

DTIC Science & Technology

2005-02-01

laser -based flow visualization experiments on the FSU cavity for different microjet pressures. The details of the experiments are given in Zhuang, et. al...developed that rigorously explains the role of leading edge microjets in cavity noise suppression and predicts the magnitude of noise reduction for a...given control input (that is the steady pressure at which the microjets are fired). The model is validated through comparison of its noise reduction

Linking Parents' Work Pressure and Adolescents' Well-Being: Insights into Dynamics in Dual-Earner Families.

ERIC Educational Resources Information Center

Crouter, Ann C.; Bumpus, Matthew F.; Maguire, Mary C.; McHale, Susan M.

1999-01-01

Examined connections between parents' work pressure and adolescent adjustment in 190 dual-earner families. Found that effects of work pressure on adolescent well-being were mediated by parental role overload and parent-adolescent conflict. Fathers' work pressure predicted both parents' feelings of role overload. Mothers' work pressure predicted…

The apelin peptides as putative targets in cardiovascular drug discovery and development.

PubMed

Charles, Cj

2008-01-01

Apelin is a recently isolated peptide that appears to act as an endogenous ligand for the previously orphaned G-protein-coupled receptor APJ. A number of studies have reported cardiovascular actions of apelin, including changes in the blood pressure and potent inotropic actions. Furthermore, perturbations of both apelin and APJ within the myocardial tissue and circulating levels of the peptide have been reported in a number of cardiovascular disease states. Taken together, these studies suggest a role for apelin in the pressure/volume homeostasis and in the pathophysiology of cardiovascular diseases. However, findings in the literature to date are, at times, disparate. This review highlights key areas where further work is required to clarify the role of apelin/APJ in both normal physiology and pathophysiology. Nonetheless, preliminary evidence suggests that the manipulation of this receptor/ligand peptide system may be a target for drug development, thereby offering a therapeutic benefit in cardiovascular diseases.

Empirically observed learning rates for concentrating solar power and their responses to regime change

NASA Astrophysics Data System (ADS)

Lilliestam, Johan; Labordena, Mercè; Patt, Anthony; Pfenninger, Stefan

2017-07-01

Concentrating solar power (CSP) capacity has expanded slower than other renewable technologies and its costs are still high. Until now, there have been too few CSP projects to derive robust conclusions about its cost development. Here we present an empirical study of the cost development of all operating CSP stations and those under construction, examining the roles of capacity growth, industry continuity, and policy support design. We identify distinct CSP expansion phases, each characterized by different cost pressure in the policy regime and different industry continuity. In 2008-2011, with low cost pressure and following industry discontinuity, costs increased. In the current phase, with high cost pressure and continuous industry development, costs decreased rapidly, with learning rates exceeding 20%. Data for projects under construction suggest that this trend is continuing and accelerating. If support policies and industrial structure are sustained, we see no near-term factors that would hinder further cost decreases.

Evaluation of a new pressure ulcer preventive dressing containing ceramide 2 with low frictional outer layer.

PubMed

Nakagami, Gojiro; Sanada, Hiromi; Konya, Chizuko; Kitagawa, Atsuko; Tadaka, Etsuko; Matsuyama, Yutaka

2007-09-01

This paper is a report of an evaluation of the effectiveness of a newly developed dressing for preventing persistent erythema and pressure ulcer development and improving the water-holding capacity without increasing the skin pH in bedridden older patients. Shear forces and skin dryness play important roles in persistent erythema and pressure ulcer development. To eliminate these risks, we developed a dressing to reduce shear forces and improve the water-holding capacity. However, the effects of this dressing in clinical settings remain unknown. An experimental bilateral comparison study was conducted at a hospital in Japan in 2004 with 37 bedridden older patients at risk of pressure ulcer development. The dressing was randomly applied to the right or left greater trochanter for 3 weeks. No dressing was applied to the opposite side as a control. The skin was monitored weekly during the 3-week application for persistent erythema and pressure ulcer development. Skin hydration and pH were also assessed during the intervention and for 1 week after dressing removal. The incidence of persistent erythema was significantly lower in the intervention area than the control area [P = 0.007, RR 0.18 (95% CI: 0.05-0.73) and NNT 4.11 (2.50-11.63) ]. No pressure ulcers occurred in either the intervention or control area. Skin hydration increased significantly during dressing application and remained high after removal (P < 0.001) relative to the control area. Skin pH decreased significantly during the application (P < 0.001) but returned to control levels after removal (P = 0.38). This safe and effective dressing can be used for patients with highly prominent bones and dry skin to prevent pressure ulcers.

Early Career Academic Perceptions, Attitudes and Professional Development Activities: Questioning the Teaching and Research Gap to Further Academic Development

ERIC Educational Resources Information Center

Matthews, Kelly E.; Lodge, Jason M.; Bosanquet, Agnes

2014-01-01

Early career academia is a challenging time, particularly as academics are facing increasing pressures to excel across a range of areas. Boyer argued for the "true scholar" versed in the overlapping areas of scholarship in research, teaching, integration and engagement. Academic developers have an important role to play in assisting the…

Waterjet processes for coating removal

NASA Technical Reports Server (NTRS)

Burgess, Fletcher; Cosby, Steve; Hoppe, David

1995-01-01

USBI and NASA have been testing and investigating the use of high pressure water for coating removal for approximately the past 12 years at the Automated TPS (Thermal Protection System - ablative materials used for thermal protection during ascent and descent of the solid rocket boosters) Removal Facility located in the Productivity Enhancement Complex at Marshall Space Flight Center. Originally the task was to develop and automate the removal process and transfer the technology to a production facility at Kennedy Space Center. Since that time more and more applications and support roles for the waterjet technology have been realized. The facility has become a vital part of development activities ongoing at MSFC. It supports the development of environmentally compliant insulations, sealants, and coatings. It also supports bonding programs, test motors, and pressure vessels. The most recent role of the cell is supporting Thiokol Corporation's solid rocket motor program in the development of waterjet degreasing and paint stripping methods. Currently vapor degreasing methods use 500,000 lbs. of ozone depleting chemicals per year. This paper describes the major cell equipment, test methods practiced, and coatings that have been removed.

Association between driving pressure and development of postoperative pulmonary complications in patients undergoing mechanical ventilation for general anaesthesia: a meta-analysis of individual patient data.

PubMed

Neto, Ary Serpa; Hemmes, Sabrine N T; Barbas, Carmen S V; Beiderlinden, Martin; Fernandez-Bustamante, Ana; Futier, Emmanuel; Gajic, Ognjen; El-Tahan, Mohamed R; Ghamdi, Abdulmohsin A Al; Günay, Ersin; Jaber, Samir; Kokulu, Serdar; Kozian, Alf; Licker, Marc; Lin, Wen-Qian; Maslow, Andrew D; Memtsoudis, Stavros G; Reis Miranda, Dinis; Moine, Pierre; Ng, Thomas; Paparella, Domenico; Ranieri, V Marco; Scavonetto, Federica; Schilling, Thomas; Selmo, Gabriele; Severgnini, Paolo; Sprung, Juraj; Sundar, Sugantha; Talmor, Daniel; Treschan, Tanja; Unzueta, Carmen; Weingarten, Toby N; Wolthuis, Esther K; Wrigge, Hermann; Amato, Marcelo B P; Costa, Eduardo L V; de Abreu, Marcelo Gama; Pelosi, Paolo; Schultz, Marcus J

2016-04-01

Protective mechanical ventilation strategies using low tidal volume or high levels of positive end-expiratory pressure (PEEP) improve outcomes for patients who have had surgery. The role of the driving pressure, which is the difference between the plateau pressure and the level of positive end-expiratory pressure is not known. We investigated the association of tidal volume, the level of PEEP, and driving pressure during intraoperative ventilation with the development of postoperative pulmonary complications. We did a meta-analysis of individual patient data from randomised controlled trials of protective ventilation during general anesthaesia for surgery published up to July 30, 2015. The main outcome was development of postoperative pulmonary complications (postoperative lung injury, pulmonary infection, or barotrauma). We included data from 17 randomised controlled trials, including 2250 patients. Multivariate analysis suggested that driving pressure was associated with the development of postoperative pulmonary complications (odds ratio [OR] for one unit increase of driving pressure 1·16, 95% CI 1·13-1·19; p<0·0001), whereas we detected no association for tidal volume (1·05, 0·98-1·13; p=0·179). PEEP did not have a large enough effect in univariate analysis to warrant inclusion in the multivariate analysis. In a mediator analysis, driving pressure was the only significant mediator of the effects of protective ventilation on development of pulmonary complications (p=0·027). In two studies that compared low with high PEEP during low tidal volume ventilation, an increase in the level of PEEP that resulted in an increase in driving pressure was associated with more postoperative pulmonary complications (OR 3·11, 95% CI 1·39-6·96; p=0·006). In patients having surgery, intraoperative high driving pressure and changes in the level of PEEP that result in an increase of driving pressure are associated with more postoperative pulmonary complications. However, a randomised controlled trial comparing ventilation based on driving pressure with usual care is needed to confirm these findings. None. Copyright © 2016 Elsevier Ltd. All rights reserved.

Left-Ventricular Energetics in Pulmonary Arterial Hypertension-Induced Right-Ventricular Hypertrophic Failure

PubMed Central

Han, June-Chiew; Guild, Sarah-Jane; Pham, Toan; Nisbet, Linley; Tran, Kenneth; Taberner, Andrew J.; Loiselle, Denis S.

2018-01-01

Pulmonary arterial hypertension (PAH) alters the geometries of both ventricles of the heart. While the right ventricle (RV) hypertrophies, the left ventricle (LV) atrophies. Multiple lines of clinical and experimental evidence lead us to hypothesize that the impaired stroke volume and systolic pressure of the LV are a direct consequence of the effect of pressure overload in the RV, and that atrophy in the LV plays only a minor role. In this study, we tested this hypothesis by examining the mechanoenergetic response of the atrophied LV to RV hypertrophy in rats treated with monocrotaline. Experiments were performed across multiple-scales: the whole-heart in vivo and ex vivo, and its trabeculae in vitro. Under the in vivo state where the RV was pressure-overloaded, we measured reduced systemic blood pressure and LV ventricular pressure. In contrast, under both ex vivo and in vitro conditions, where the effect of RV pressure overload was circumvented, we found that LV was capable of developing normal systolic pressure and stress. Nevertheless, LV atrophy played a minor role in that LV stroke volume remained lower, thereby contributing to lower LV mechanical work output. Concomitantly lower oxygen consumption and change of enthalpy were observed, and hence LV energy efficiency was unchanged. Our internally consistent findings between working-heart and trabecula experiments explain the rapid improvement of LV systolic function observed in patients with chronic pulmonary hypertension following surgical relief of RV pressure overload. PMID:29375394

Importance of nutrition in preventing and treating pressure ulcers.

PubMed

Taylor, Carolyn

2017-06-30

Pressure ulcers are painful, and affect patients' health, mobility and well-being. They also cost the NHS between £1.4-2.1 billion a year. Although a large proportion of pressure ulcers are avoidable, many still occur and, because pressure ulcer incidence is an indicator of care quality, it can put carers under scrutiny. The National Institute for Health and Care Excellence states that adequate risk assessment of pressure ulcer development, including the role of malnutrition, improves care. Adequate nutrition is vital for the prevention of pressure ulcers and malnutrition can hinder healing when pressure ulcers have developed. The risk of malnutrition should be assessed with a recognised tool, such as the Malnutrition Universal Screening Tool, and appropriate treatment plans should be drawn up for patients identified as being at risk of malnutrition to improve their nutritional state. For example, the dietary intake of people with poor appetite can be supplemented with nutritious snacks between meals. The aims of this article are to help readers understand risk factors for malnutrition and how dietary intake can be manipulated to improve patients' nutritional state. It also aims to highlight how improving nutritional intake helps to prevent pressure ulcers. On completing the article, readers will be able to consider and review their own practice.

Characterization of excess pore pressures at the toe of the Nankai accretionary complex, Ocean Drilling Program sites 1173, 1174, and 808: Results of one-dimensional modeling

NASA Astrophysics Data System (ADS)

Gamage, K.; Screaton, E.

2006-04-01

Elevated fluid pore pressures play a critical role in the development of accretionary complexes, including the development of the décollement zone. In this study, we used measured permeabilities of core samples from Ocean Drilling Program (ODP) Leg 190 to develop a permeability-porosity relationship for hemipelagic sediments at the toe of the Nankai accretionary complex. This permeability-porosity relationship was used in a one-dimensional loading and fluid flow model to simulate excess pore pressures and porosities. Simulated excess pore pressure ratios (as a fraction of lithostatic pressure-hydrostatic pressure) using the best fit permeability-porosity relationship were lower than predicted from previous studies. We then tested sensitivity of excess pore pressure ratios in the underthrust sediments to bulk permeability, lateral stress in the prism, and a hypothetical low-permeability barrier at the décollement. Our results demonstrated significant increase in pore pressures below the décollement with lower bulk permeability, such as obtained by using the lower boundary of permeability-porosity data, or when a low-permeability barrier is added at the décollement. In contrast, pore pressures in the underthrust sediments demonstrated less sensitivity to added lateral stresses in the prism, although the profile of the excess pore pressure ratio is affected. Both simulations with lateral stress and a low-permeability barrier at the décollement resulted in sharp increases in porosity at the décollement, similar to that observed in measured porosities. Furthermore, in both scenarios, maximum excess pore pressure ratios were found at the décollement, suggesting that either of these factors would contribute to stable sliding along the décollement.

Developing VET Applied Research: Steps towards Enhancing VET's Role in the Innovation System

ERIC Educational Resources Information Center

Beddie, Francesca M.; Simon, Linda

2017-01-01

The VET sector is under pressure from the exponential increase in university places. This, on top of cutbacks to government funding over the last decade and a lack of clarity about VET's role now that it is squeezed between universities and schools, has led to a precarious position for the VET sector and the need to consider changes to traditional…

Association between ventilatory settings and development of acute respiratory distress syndrome in mechanically ventilated patients due to brain injury.

PubMed

Tejerina, Eva; Pelosi, Paolo; Muriel, Alfonso; Peñuelas, Oscar; Sutherasan, Yuda; Frutos-Vivar, Fernando; Nin, Nicolás; Davies, Andrew R; Rios, Fernando; Violi, Damian A; Raymondos, Konstantinos; Hurtado, Javier; González, Marco; Du, Bin; Amin, Pravin; Maggiore, Salvatore M; Thille, Arnaud W; Soares, Marco Antonio; Jibaja, Manuel; Villagomez, Asisclo J; Kuiper, Michael A; Koh, Younsuck; Moreno, Rui P; Zeggwagh, Amine Ali; Matamis, Dimitrios; Anzueto, Antonio; Ferguson, Niall D; Esteban, Andrés

2017-04-01

In neurologically critically ill patients with mechanical ventilation (MV), the development of acute respiratory distress syndrome (ARDS) is a major contributor to morbidity and mortality, but the role of ventilatory management has been scarcely evaluated. We evaluate the association of tidal volume, level of PEEP and driving pressure with the development of ARDS in a population of patients with brain injury. We performed a secondary analysis of a prospective, observational study on mechanical ventilation. We included 986 patients mechanically ventilated due to an acute brain injury (hemorrhagic stroke, ischemic stroke or brain trauma). Incidence of ARDS in this cohort was 3%. Multivariate analysis suggested that driving pressure could be associated with the development of ARDS (odds ratio for unit increment of driving pressure 1.12; confidence interval for 95%: 1.01 to 1.23) whereas we did not observe association for tidal volume (in ml per kg of predicted body weight) or level of PEEP. ARDS was associated with an increase in mortality, longer duration of mechanical ventilation, and longer ICU length of stay. In a cohort of brain-injured patients the development of ARDS was not common. Driving pressure was associated with the development of this disease. Copyright © 2016 Elsevier Inc. All rights reserved.

Research and Development of High-performance Explosives

PubMed Central

Cornell, Rodger; Wrobel, Erik; Anderson, Paul E.

2016-01-01

Developmental testing of high explosives for military applications involves small-scale formulation, safety testing, and finally detonation performance tests to verify theoretical calculations. small-scale For newly developed formulations, the process begins with small-scale mixes, thermal testing, and impact and friction sensitivity. Only then do subsequent larger scale formulations proceed to detonation testing, which will be covered in this paper. Recent advances in characterization techniques have led to unparalleled precision in the characterization of early-time evolution of detonations. The new technique of photo-Doppler velocimetry (PDV) for the measurement of detonation pressure and velocity will be shared and compared with traditional fiber-optic detonation velocity and plate-dent calculation of detonation pressure. In particular, the role of aluminum in explosive formulations will be discussed. Recent developments led to the development of explosive formulations that result in reaction of aluminum very early in the detonation product expansion. This enhanced reaction leads to changes in the detonation velocity and pressure due to reaction of the aluminum with oxygen in the expanding gas products. PMID:26966969

Polarized pressure dependence of the anisotropic dielectric functions of highly oriented poly(p-phenylene vinylene)

NASA Astrophysics Data System (ADS)

Morandi, V.; Galli, M.; Marabelli, F.; Comoretto, D.

2010-04-01

In this work, we combined an experimental technique and a detailed data analysis to investigate the influence of an applied pressure on the anisotropic dielectric functions of highly oriented poly(p-phenylene vinylene) (PPV). The dielectric constants were derived from polarized reflectance spectra recorded through a diamond anvil cell up to 50 kbar. The presence of the diamond anvils strongly affects measured spectra requiring the development in an optical model able to take all spurious effects into account. A parametric procedure was then applied to derive the complex dielectric constants for both polarizations as a function of pressure. A detailed analysis of their pressure dependence allows addressing the role of intermolecular interactions and electron-phonon coupling in highly oriented PPV.

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.

Fast circulation of cerebrospinal fluid: an alternative perspective on the protective role of high intracranial pressure in ocular hypertension.

PubMed

Wostyn, Peter; De Groot, Veva; Van Dam, Debby; Audenaert, Kurt; Killer, Hanspeter Esriel; De Deyn, Peter Paul

2016-05-01

As ocular hypertension refers to a condition in which the intraocular pressure is consistently elevated but without development of glaucoma, study of it may provide important clues to factors that may play a protective role in glaucoma. β-amyloid, one of the key histopathological findings in Alzheimer's disease, has been reported to increase by chronic elevation of intraocular pressure in animals with experimentally induced ocular hypertension and to cause retinal ganglion cell death, pointing to similarities in molecular cell death mechanisms between glaucoma and Alzheimer's disease. On the other hand, recent studies have reported that intracranial pressure is higher in patients with ocular hypertension compared with controls, giving rise to the idea that elevated intracranial pressure may provide a protective effect for the optic nerve by decreasing the trans-lamina cribrosa pressure difference. The speculation that the higher intracranial pressure reported in ocular hypertension patients may protect against glaucoma mainly through a lower trans-lamina cribrosa pressure difference remains at least questionable. Here, we present an alternative viewpoint, according to which the protective effect of higher intracranial pressure could be due, at least in part, to a pressure-independent mechanism, namely faster cerebrospinal fluid production leading to increased cerebrospinal fluid turnover with enhanced removal of potentially neurotoxic waste products that accumulate in the optic nerve. This suggests a new hypothesis for glaucoma, which, just like Alzheimer's disease, may be considered then as an imbalance between production and clearance of neurotoxins, including β-amyloid. If confirmed, then strategies to improve cerebrospinal fluid flow are reasonable and could provide a new therapeutic approach for stopping the neurotoxic β-amyloid pathway in glaucoma. © 2015 The Authors. Clinical and Experimental Optometry © 2015 Optometry Australia.

Headaches secondary to intraventricular silicone oil successfully managed with ventriculoperitoneal shunt.

PubMed

Hruby, Paul M; Poley, Preeti R; Terp, Patricia A; Thorell, William E; Margalit, Eyal

2013-01-01

To describe a case of intravitreal silicone oil (SO) migration into the cerebral ventricles with secondary chronic headaches. Retrospective case report. Chart review. Single patient. A 51-year-old man with a history of proliferative diabetic retinopathy underwent surgery for traction retinal detachment using SO. Postoperatively, he developed elevated intraocular pressure, headaches, and a blind painful eye, which was enucleated. Neuroimaging revealed SO within the cerebral ventricles. Five years after the initial retinal detachment surgery, the patient developed chronic headaches. Lumbar puncture revealed an elevated opening pressure. The headaches were initially managed medically. A ventriculoperitoneal shunt was placed after the headaches persisted, which resulted in their complete resolution at 6 weeks after shunt placement. Ocular hypertension after intravitreal SO placement may play a role in SO intracranial migration. In the case presented, intraventricular SO was the apparent cause of elevated intracranial pressure and headaches. As all published cases of intraventricular SO migration reporting intraocular pressure to this point have described ocular hypertension, careful monitoring of intraocular pressure and aggressive control of ocular hypertension in the presence of intravitreal SO is recommended.

Peace Corps Volunteers and the Boundaries of Bottom-Up Development: Mongolia, a Case Study

ERIC Educational Resources Information Center

Schuckman, Hugh Erik

2012-01-01

From President Kennedy's first announcement of a non-military US volunteer corps in 1961, the Peace Corps has been one of the preeminent government grassroots volunteer development agency. This study explores the history of the ambiguities inherent in this contention, pressure primarily stemming from the organization's role as both a governmental…

Rapid Development of Orion Structural Test Systems

NASA Astrophysics Data System (ADS)

Baker, Dave

2012-07-01

NASA is currently validating the Orion spacecraft design for human space flight. Three systems developed by G Systems using hardware and software from National Instruments play an important role in the testing of the new Multi- purpose crew vehicle (MPCV). A custom pressurization and venting system enables engineers to apply pressure inside the test article for measuring strain. A custom data acquisition system synchronizes over 1,800 channels of analog data. This data, along with multiple video and audio streams and calculated data, can be viewed, saved, and replayed in real-time on multiple client stations. This paper presents design features and how the system works together in a distributed fashion.

Variability and repeatability analysis of plantar pressure during gait in older people.

PubMed

Franco, Pedro S; Silva, Caio Borella P da; Rocha, Emmanuel S da; Carpes, Felipe P

2015-01-01

Repeatability and variability of the plantar pressure during walking are important components in the clinical assessment of the elderly. However, there is a lack of information on the uniformity of plantar pressure patterns in the elderly. To analyze the repeatability and variability in plantar pressure considering mean, peak and asymmetries during aged gait. Plantar pressure was monitored in four different days for ten elderly subjects (5 female), with mean±standard-deviation age of 73±6 years, walking barefoot at preferred speed. Data were compared between steps for each day and between different days. Mean and peak plantar pressure values were similar between the different days of evaluation. Asymmetry indexes were similar between the different days evaluated. Plantar pressure presented a consistent pattern in the elderly. However, the asymmetry indexes observed suggest that the elderly are exposed to repetitive asymmetric loading during locomotion. Such result requires further investigation, especially concerning the role of these asymmetries for development of articular injuries. Copyright © 2015 Elsevier Editora Ltda. All rights reserved.

[Essential hypertension and stress. When do yoga, psychotherapy and autogenic training help?].

PubMed

Herrmann, J M

2002-05-09

Psychosocial factors play an important role in the development and course of essential hypertension, although "stress" can account for only 10% of blood pressure variance. A variety of psychotherapeutic interventions, such as relaxation techniques (autogenic training or progressive muscular relaxation), behavioral therapy or biofeedback techniques, can lower elevated blood pressure by an average of 10 mmHg (systolic) and 5 mmHg (diastolic). As a "secondary effect", such measures may also prompt the hypertensive to adopt a more health-conscious lifestyle.

Design and development of novel bandages for compression therapy.

PubMed

Rajendran, Subbiyan; Anand, Subhash

2003-03-01

During the past few years there have been increasing concerns relating to the performance of bandages, especially their pressure distribution properties for the treatment of venous leg ulcers. This is because compression therapy is a complex system and requires two or multi-layer bandages, and the performance properties of each layer differs from other layers. The widely accepted sustained graduated compression mainly depends on the uniform pressure distribution of different layers of bandages, in which textile fibres and bandage structures play a major role. This article examines how the fibres, fibre blends and structures influence the absorption and pressure distribution properties of bandages. It is hoped that the research findings will help medical professionals, especially nurses, to gain an insight into the development of bandages. A total of 12 padding bandages have been produced using various fibres and fibre blends. A new technique that would facilitate good resilience and cushioning properties, higher and more uniform pressure distribution and enhanced water absorption and retention was adopted during the production. It has been found that the properties of developed padding bandages, which include uniform pressure distribution around the leg, are superior to existing commercial bandages and possess a number of additional properties required to meet the criteria stipulated for an ideal padding bandage. Results have indicated that none of the mostly used commercial padding bandages provide the required uniform pressure distribution around the limb.

Hypertension in the US Black population: risk factors, complications, and potential impact of central aortic pressure on effective treatment.

PubMed

Ferdinand, Keith C; Townsend, Raymond R

2012-04-01

The identification of specific factors that contribute to hypertension development and progression among blacks in the US is the focus of much ongoing research. The purpose of this paper is to review these factors and discuss how they present unique opportunities for improving the management of hypertension in this difficult-to-treat population. We searched the published literature for articles discussing the risk factors for hypertension and cardiovascular disease in blacks; the target-organ damage and cardiovascular complications associated with hypertension in this difficult-to-treat population; and the role of central blood pressure in predicting cardiovascular events. The prevalence of hypertension is higher in blacks than in other race/ethnic groups, with environmental and genetic risk factors likely playing an important role. The cardiovascular and renal consequences of hypertension (eg, left ventricular hypertrophy and renal failure) are also greater in blacks relative to their white counterparts. Preliminary data suggest that central blood pressure may be higher in blacks than in whites and has the potential for greater prognostic capability relative to peripheral blood pressure. There is an urgent need to successfully control hypertension in the black population. Although data are limited in blacks, evidence suggests that central blood pressure warrants more continued assessment in future clinical studies.

Does blood pressure lowering treatment prevents dementia or cognitive decline in patients with cardiovascular and cerebrovascular disease?

PubMed

Feigin, Valery; Ratnasabapathy, Yogini; Anderson, Craig

2005-03-15

There is increasing evidence that both hypertension and stroke play important roles in the development of cognitive decline and dementia. Despite five high-quality randomised controlled trials (RCTs) in this area to date, there remains uncertainty about the role of blood pressure lowering therapy in the prevention of cognitive decline and dementia. It appears that lack of definitive results from these trials can be explained on the basis of (a) insufficient power to detect modest treatment effects; (b) measurement error in the diagnosis of dementia; (c) variations in the treatment effects between different types of antihypertensive agents; and (d) bias due to missing data, variation in baseline factors such as levels of blood pressure, and the inclusion of patients with cognitive impairment at entry. Preliminary meta-analysis of RCTs supports the hypothesis that blood pressure lowering may prevent dementia in high-risk patients, that is those with vascular disease. However, a meta-analysis of individual patient data (IPD) from these, and other relevant trials in patients with vascular disease, would provide much more reliable data. If the hypothesis were confirmed, it would certainly be of considerable importance not only in terms of our understanding of the aetiology of dementia, but also in promoting blood pressure lowering strategies for broader public health good.

A Superintendent's Role in Creating Community

ERIC Educational Resources Information Center

Ahillen, Marybeth

2010-01-01

The context of leadership in the public school has become increasingly complex with the pressures of high stakes testing and accountability, changing student demographics, and financial challenges. Stakeholders must work together to develop effective strategies to increase student academic performance. Successful superintendents must optimize…

Career development. Private lives.

PubMed

Hunt, Louise; Mooney, Helen

2009-01-22

Ensure the private sector job fits your career aims--don't simply take the first offer. Moving to the private sector can bring more freedom, but also more pressure to be entrepeneurial. A stint in the private sector can prepare you for roles back in the NHS.

Blood pressure as a therapeutic target in stroke.

PubMed

Armario, Pedro; de la Sierra, Alejandro

2009-01-01

Stroke, as a clinical manifestation of the cardiovascular diseases, is one of the leading causes of death and disability in both developed and developing countries. Hypertension is by far, the most important risk factor for stroke. Epidemiological data indicate that the risk of stroke increases with both systolic and diastolic blood pressure elevation, from levels of 115/75 mmHg. It is also evident that most adults worldwide have values above these limits, thus emphasizing the importance of blood pressure as a risk factor for stroke. Clinical trials of antihypertensive treatment, both in studies that have compared active drugs against placebo or in those comparing different types of drugs have clearly demonstrated a protective effect of blood pressure reduction in the prevention of stroke. The degree of protection is directly related to blood pressure reduction and, the lower the level, the better the prognosis. Although data on secondary stroke prevention are scarcer, studies also seem to indicate that lowering blood pressure with antihypertensive treatment protects against stroke recurrence. At the present moment there is still uncertainty on 2 different aspects regarding the relationship between antihypertensive treatment and stroke. First, the blood pressure management during acute stroke has not adequately investigated in clinical trials. Second, the possibility of a protective role of specific types of antihypertensive drugs beyond blood pressure reduction is a matter of debate. Independently of these unresolved issues, prevention of hypertension development by lifestyle changes and adequate treatment and control to the hypertensive population will be a very effective measure in reducing stroke incidence, stroke recurrence, and stroke mortality.

Formwork pressure exerted by self-consolidating concrete

NASA Astrophysics Data System (ADS)

Omran, Ahmed Fathy

Self-consolidating concrete (SCC) is an emerging technology that utilizes flowable concrete that eliminates the need for consolidation. The advantages of SCC lie in a remarkable reduction of the casting time, facilitating the casting of congested and complex structural elements, possibility to reduce labor demand, elimination of mechanical vibrations and noise, improvement of surface appearance, producing a better and premium concrete product. The research focussed on capturing existing knowledge and making recommendations for current practice. An experimental program was undertaken at the Universite de Sherbrooke to evaluate the lateral pressure developed by SCC mixtures. A portable devise (UofS2 pressure column) for measuring and predicting lateral pressure and its rate of decay of SCC was developed and validated. The UofS2 pressure column is cast with 0.5 m high fresh concrete and air pressure is introduced from the top to simulate casting depth up to 13 m. Then, develop and implement test method for field evaluation of relevant plastic and thixotropic properties of SCC that affect formwork pressure were done. Portable vane (PV) test based on the hand-held vane test method used to determine the undrained shear strength property of clay soil was the first setup as well as the inclined plane (IP) test. The IP device involves slumping a small concrete cylinder on a horizontal plate and then lifting up the plate at different durations of rest until the slumped sample starts to move. Identifying role of material constituents, mix design, concrete placement characteristics (casting rate, waiting periods between lifts, and casting depth), temperature, and formwork characteristics that have major influence on formwork pressure exerted by SCC were evaluated in laboratory and validated by actual field measurements. Relating the maximum lateral pressure and its rate of decay to the plastic properties of SCC were established. In the analytical part of the research, effective ways to reduce lateral pressure by developing formulation expertise and practical guidelines to lower lateral pressure of SCC were proposed. Various design equations as well as chart diagrams to predict formwork pressure that can be exerted by SCC on column and wall elements were derived and reported. In general, the results obtained show that measured lateral pressure is lower than corresponding hydrostatic pressure. The study has shown that lateral pressure exerted by SCC is closely related to the structural build-up at rest (or thixotropy) of SCC. The latter can be controlled using different mixture proportionings, material constituents, and chemical admixtures. SCC mixture with a high rate of structural build-up at rest can develop low lateral pressure on formwork. Increased rate of structural build-up at rest can be ensured by incorporating a greater volume of coarse aggregate, lower paste volume, and/or lower sand-to-total aggregate ratio. Incorporating coarse aggregate of larger maximum size could also increase the thixotropy and hence reduce the lateral pressure. This can also be achieved by reducing the workability of SCC using less HRWRA concentration. Indeed, all mixture factors have been replaced by measuring the rate of structural build-up at rest (or thixotropy) using the developed portable vane and inclined plane field-oriented test as well as the modified Tattersall MK-III concrete rheometer. On the other hand, increasing or maintaining the concrete temperature at a certain level plays an important role to reduce the lateral pressure. The higher concrete temperature can accelerate the heat of hydration of cement with water and increase the internal friction leading to higher thixotropy. Controlling the placement rate has a great impact on the resultant lateral pressure of SCC. The lateral pressure can be reduced by slowing down the casting rate, as concrete has more time to build-up. However, this can slow down the rate of construction. The casting rate should be optimized to yield a cost effective formwork system. Pausing the continuous casting by a waiting period can reduce the exerted lateral pressure. The research investigation could accelerate the acceptance and implementation of SCC technology in cast-in-place applications, which is the preponderate business of the ready mixed concrete suppliers. The research findings could also contribute to the removal of some of the major barriers hindering the acceptance of SCC in cast-in-place applications and provide the industry with much needed guidelines on formwork pressure. (Abstract shortened by UMI.)

Using Corporate Tools for Organizational Development to Affect Cultural and Structural Change in the Academy: Gallup Impact Planning at the University of Nebraska-Lincoln

ERIC Educational Resources Information Center

Latta, Gail F.

2006-01-01

External pressures have transformed academic life, shattering the roles and relationships that created a sense of community. Increasingly the challenges of fostering an engaged workforce in these institutions mirror the corporate world. Leaders at UNL have adapted Gallup's organizational development strategy to improve faculty engagement and…

Superconductivity in highly disordered dense carbon disulfide.

PubMed

Dias, Ranga P; Yoo, Choong-Shik; Struzhkin, Viktor V; Kim, Minseob; Muramatsu, Takaki; Matsuoka, Takahiro; Ohishi, Yasuo; Sinogeikin, Stanislav

2013-07-16

High pressure plays an increasingly important role in both understanding superconductivity and the development of new superconducting materials. New superconductors were found in metallic and metal oxide systems at high pressure. However, because of the filled close-shell configuration, the superconductivity in molecular systems has been limited to charge-transferred salts and metal-doped carbon species with relatively low superconducting transition temperatures. Here, we report the low-temperature superconducting phase observed in diamagnetic carbon disulfide under high pressure. The superconductivity arises from a highly disordered extended state (CS4 phase or phase III[CS4]) at ~6.2 K over a broad pressure range from 50 to 172 GPa. Based on the X-ray scattering data, we suggest that the local structural change from a tetrahedral to an octahedral configuration is responsible for the observed superconductivity.

A computational analysis of the long-term regulation of arterial pressure

PubMed Central

Beard, Daniel A.

2013-01-01

The asserted dominant role of the kidneys in the chronic regulation of blood pressure and in the etiology of hypertension has been debated since the 1970s. At the center of the theory is the observation that the acute relationships between arterial pressure and urine production—the acute pressure-diuresis and pressure-natriuresis curves—physiologically adapt to perturbations in pressure and/or changes in the rate of salt and volume intake. These adaptations, modulated by various interacting neurohumoral mechanisms, result in chronic relationships between water and salt excretion and pressure that are much steeper than the acute relationships. While the view that renal function is the dominant controller of arterial pressure has been supported by computer models of the cardiovascular system known as the “Guyton-Coleman model”, no unambiguous description of a computer model capturing chronic adaptation of acute renal function in blood pressure control has been presented. Here, such a model is developed with the goals of: 1. representing the relevant mechanisms in an identifiable mathematical model; 2. identifying model parameters using appropriate data; 3. validating model predictions in comparison to data; and 4. probing hypotheses regarding the long-term control of arterial pressure and the etiology of primary hypertension. The developed model reveals: long-term control of arterial blood pressure is primarily through the baroreflex arc and the renin-angiotensin system; and arterial stiffening provides a sufficient explanation for the etiology of primary hypertension associated with ageing. Furthermore, the model provides the first consistent explanation of the physiological response to chronic stimulation of the baroreflex. PMID:24555102

A computational analysis of the long-term regulation of arterial pressure.

PubMed

Beard, Daniel A; Pettersen, Klas H; Carlson, Brian E; Omholt, Stig W; Bugenhagen, Scott M

2013-01-01

The asserted dominant role of the kidneys in the chronic regulation of blood pressure and in the etiology of hypertension has been debated since the 1970s. At the center of the theory is the observation that the acute relationships between arterial pressure and urine production-the acute pressure-diuresis and pressure-natriuresis curves-physiologically adapt to perturbations in pressure and/or changes in the rate of salt and volume intake. These adaptations, modulated by various interacting neurohumoral mechanisms, result in chronic relationships between water and salt excretion and pressure that are much steeper than the acute relationships. While the view that renal function is the dominant controller of arterial pressure has been supported by computer models of the cardiovascular system known as the "Guyton-Coleman model", no unambiguous description of a computer model capturing chronic adaptation of acute renal function in blood pressure control has been presented. Here, such a model is developed with the goals of: 1. representing the relevant mechanisms in an identifiable mathematical model; 2. identifying model parameters using appropriate data; 3. validating model predictions in comparison to data; and 4. probing hypotheses regarding the long-term control of arterial pressure and the etiology of primary hypertension. The developed model reveals: long-term control of arterial blood pressure is primarily through the baroreflex arc and the renin-angiotensin system; and arterial stiffening provides a sufficient explanation for the etiology of primary hypertension associated with ageing. Furthermore, the model provides the first consistent explanation of the physiological response to chronic stimulation of the baroreflex.

Efficacy of a pressure-sensing mattress cover system for reducing interface pressure: study protocol for a randomized controlled trial.

PubMed

Wong, Holly; Kaufman, Jaime; Baylis, Barry; Conly, John M; Hogan, David B; Stelfox, Henry T; Southern, Danielle A; Ghali, William A; Ho, Chester H

2015-09-29

Interface pressure is a key risk factor in the development of pressure ulcers. Visual feedback of continuous interface pressure between the body and support surface could inform clinicians on repositioning strategies and play a key role in an overall strategy for the prevention and management of pressure ulcers. A parallel two-group randomized controlled clinical trial will be conducted to study the effect of continuous pressure imaging on reducing interface pressure and on the incidence of pressure ulcers in vulnerable hospital patients. A total of 678 eligible consenting inpatients at risk of pressure ulcer development in a tertiary acute care institution will be randomly allocated to either having the ForeSite PT™ system with the liquid-crystal display monitor turned on to provide visual feedback to the clinicians while also collecting continuous interface pressure data (intervention group) or to having the ForeSite PT™ system with monitor turned off (that is, not providing visual feedback) but still collecting continuous interface pressure data (control group), in a ratio of 1:1. Continuous interface pressure data will be collected in both groups for 3 days (72 h). Data collection will continue until discharge for a subset of approximately 60 patients. The primary outcome will be the differences in the two groups' interface pressure analysis. Interface pressure readings will be collected through hourly samplings of continuous interface pressure recordings. Secondary outcomes will be the differences between the two groups in pressure-related skin and soft tissue changes in areas at risk of pressure ulcer (obtained at baseline within 24 h of admission) and on the third day of the trial or at discharge and perceptions of the intervention by patients and clinicians (obtained on the third day or at discharge). This will be the first randomized controlled trial to investigate the effect of visual feedback with continuous interface pressure of vulnerable hospital patients across different care settings, and the association between interface pressure and development of pressure-related skin and soft tissue changes. The results could provide important information to guide clinical practice in the prevention and management of pressure ulcers. ClinicalTrials.gov NCT02325388 (date of registration: 24 December 2014).

Social learning and the development of individual and group behaviour in mammal societies

PubMed Central

Thornton, Alex; Clutton-Brock, Tim

2011-01-01

As in human societies, social learning may play an important role in shaping individual and group characteristics in other mammals. Here, we review research on non-primate mammals, concentrating on work at our long-term meerkat study site, where longitudinal data and field experiments have generated important insights into the role of social learning under natural conditions. Meerkats live under high predation pressure and occupy a difficult foraging niche. Accordingly, pups make extensive use of social information in learning to avoid predation and obtain food. Where individual learning is costly or opportunities are lacking, as in the acquisition of prey-handling skills, adults play an active role in promoting learning through teaching. Social learning can also cause information to spread through groups, but our data suggest that this does not necessarily result in homogeneous, group-wide traditions. Moreover, traditions are commonly eroded by individual learning. We suggest that traditions will only persist where there are high costs of deviating from the group norm or where skill development requires extensive time and effort. Persistent traditions could, theoretically, modify selection pressures and influence genetic evolution. Further empirical studies of social learning in natural populations are now urgently needed to substantiate theoretical claims. PMID:21357220

Social learning and the development of individual and group behaviour in mammal societies.

PubMed

Thornton, Alex; Clutton-Brock, Tim

2011-04-12

As in human societies, social learning may play an important role in shaping individual and group characteristics in other mammals. Here, we review research on non-primate mammals, concentrating on work at our long-term meerkat study site, where longitudinal data and field experiments have generated important insights into the role of social learning under natural conditions. Meerkats live under high predation pressure and occupy a difficult foraging niche. Accordingly, pups make extensive use of social information in learning to avoid predation and obtain food. Where individual learning is costly or opportunities are lacking, as in the acquisition of prey-handling skills, adults play an active role in promoting learning through teaching. Social learning can also cause information to spread through groups, but our data suggest that this does not necessarily result in homogeneous, group-wide traditions. Moreover, traditions are commonly eroded by individual learning. We suggest that traditions will only persist where there are high costs of deviating from the group norm or where skill development requires extensive time and effort. Persistent traditions could, theoretically, modify selection pressures and influence genetic evolution. Further empirical studies of social learning in natural populations are now urgently needed to substantiate theoretical claims.

Psychophysiology of arterial baroreceptors and the etiology of hypertension.

PubMed

Rau, H; Elbert, T

2001-01-01

Arterial baroreceptors are sensitive to blood pressure dependent blood vessel dilation. They play a key role in the short term regulation of blood pressure. Their impact on psychological and psychophysiological aspects is of increasing interest. The review focuses on experimental techniques for the controlled baroreceptor manipulation. Results from the application of these techniques show that baroreceptor activation influences the cardiovascular system as well as central nervous functioning: Behavioral and electrophysiological measures of arousal, low level reflexes and pain responses are modulated through baroreceptor manipulation. The observation of an overall dampening ('barbiturate like') effect of baroreceptor activity led Dworkin et al. formulate the theory of learned hypertension: Subjects might experience blood pressure dependent baroreceptor activation as stress and pain relieving. High blood pressure periods become negatively reinforced. Phasic high blood pressure might develop as a coping strategy. Data from a longitudinal human study supporting this theory are reported.

CRISTAPRESS: an optical cell for structure development in high-pressure crystallization.

PubMed

Boyer, S A E; Fournier, F E J; Gandin, Ch-A; Haudin, J-M

2014-01-01

An original optical high-pressure cell, named CRISTAPRESS, has been especially designed to investigate phase transitions of complex liquids, i.e., polymers, polymer blends, nano-composites, etc. The design of the cell is based on the optical properties of morphological entities through in situ light depolarizing microscopic observations. Pressure up to 200 MPa with a fine temperature control up to 300 °C can be applied. A striking advantage of this cell is the possibility to select the pressure transmitting medium that can be water, silicone oil, a fluid in the supercritical state, etc. The potential of the novel technique was demonstrated by carrying out time-resolved measurements during polymer crystallization induced by water pressure. These preliminary experimental investigations permit to discriminate the role of the barometric and thermal histories on the kinetics of polymer growth, as well as on the subsequent morphologies. It should lead to new reliable crystallization kinetics models.

WHAT'S SO SPECIAL ABOUT THE DEVELOPING IMMUNE SYSTEM? (Journal Article)

EPA Science Inventory

The evolution of the subdiscipline of developmental immunotoxicology (DIT) as it exists today has been shaped by significant regulatory pressures as well as key scientific advances. This review considers the role played by legislation to protect children’s health, and on the eme...

Detailed numerical simulations of laser cooling processes

NASA Technical Reports Server (NTRS)

Ramirez-Serrano, J.; Kohel, J.; Thompson, R.; Yu, N.

2001-01-01

We developed a detailed semiclassical numerical code of the forces applied on atoms in optical and magnetic fields to increase the understanding of the different roles that light, atomic collisions, background pressure, and number of particles play in experiments with laser cooled and trapped atoms.

Molecular dynamics simulations of disjoining pressure effects in ultra-thin water films on a metal surface

NASA Astrophysics Data System (ADS)

Hu, Han; Sun, Ying

2013-11-01

Disjoining pressure, the excess pressure in an ultra-thin liquid film as a result of van der Waals interactions, is important in lubrication, wetting, flow boiling, and thin film evaporation. The classic theory of disjoining pressure is developed for simple monoatomic liquids. However, real world applications often utilize water, a polar liquid, for which fundamental understanding of disjoining pressure is lacking. In the present study, molecular dynamics (MD) simulations are used to gain insights into the effect of disjoining pressure in a water thin film. Our MD models were firstly validated against Derjaguin's experiments on gold-gold interactions across a water film and then verified against disjoining pressure in an argon thin film using the Lennard-Jones potential. Next, a water thin film adsorbed on a gold surface was simulated to examine the change of vapor pressure with film thickness. The results agree well with the classic theory of disjoining pressure, which implies that the polar nature of water molecules does not play an important role. Finally, the effects of disjoining pressure on thin film evaporation in nanoporous membrane and on bubble nucleation are discussed.

Response of the urethral and intracorporeal pressures to cavernosus muscle stimulation: role of the muscles in erection and ejaculation.

PubMed

Shafik, A

1995-07-01

The role of the bulbocavernosus (BC) and ischiocavernosus (IC) muscles in erection and ejaculation was studied. The response of the urethral and intracorporeal pressure to cavernosus muscle stimulation was evaluated in 18 male volunteers (mean age, 36.6 years). A two-channel microtip catheter was placed in the prostatic and bulbous urethra. Muscle stimulation was done by two needle electrodes inserted into the BC and IC muscles. BC muscle stimulation caused an increase in the pressure of the bulbous urethra (P < 0.001) and corpus spongiosum (P < 0.01) and an insignificant change in the prostatic and pendulous urethral and corpus cavernosal pressures (difference not significant). IC muscle stimulation effected an increase in the corpus cavernosal pressure (P < 0.001) without changing the urethral pressure (difference not significant). The BC muscle contracts rhythmically at orgasm and this might help to eject the semen from the posterior to the anterior urethra. It is apparent that the muscle has minimal or no role in erection. IC muscle may have a role in erection by increasing the intracavernosal pressure. It seems that it has no role in ejaculation. BC may be considered the "muscle of ejaculation," and IC the "muscle of erection."

Systemic leukotriene B4 receptor antagonism lowers arterial blood pressure and improves autonomic function in the spontaneously hypertensive rat

PubMed Central

Marvar, Paul J.; Hendy, Emma B.; Cruise, Thomas D.; Walas, Dawid; DeCicco, Danielle; Vadigepalli, Rajanikanth; Schwaber, James S.; Waki, Hidefumi; Murphy, David

2016-01-01

Key points Evidence indicates an association between hypertension and chronic systemic inflammation in both human hypertension and experimental animal models.Previous studies in the spontaneously hypertensive rat (SHR) support a role for leukotriene B4 (LTB4), a potent chemoattractant involved in the inflammatory response, but its mode of action is poorly understood.In the SHR, we observed an increase in T cells and macrophages in the brainstem; in addition, gene expression profiling data showed that LTB4 production, degradation and downstream signalling in the brainstem of the SHR are dynamically regulated during hypertension.When LTB4 receptor 1 (BLT1) receptors were blocked with CP‐105,696, arterial pressure was reduced in the SHR compared to the normotensive control and this reduction was associated with a significant decrease in systolic blood pressure (BP) indicators.These data provide new evidence for the role of LTB4 as an important neuro‐immune pathway in the development of hypertension and therefore may serve as a novel therapeutic target for the treatment of neurogenic hypertension. Abstract Accumulating evidence indicates an association between hypertension and chronic systemic inflammation in both human hypertension and experimental animal models. Previous studies in the spontaneously hypertensive rat (SHR) support a role for leukotriene B4 (LTB4), a potent chemoattractant involved in the inflammatory response. However, the mechanism for LTB4‐mediated inflammation in hypertension is poorly understood. Here we report in the SHR, increased brainstem infiltration of T cells and macrophages plus gene expression profiling data showing that LTB4 production, degradation and downstream signalling in the brainstem of the SHR are dynamically regulated during hypertension. Chronic blockade of the LTB4 receptor 1 (BLT1) receptor with CP‐105,696, reduced arterial pressure in the SHR compared to the normotensive control and this reduction was associated with a significant decrease in low and high frequency spectra of systolic blood pressure, and an increase in spontaneous baroreceptor reflex gain (sBRG). These data provide new evidence for the role of LTB4 as an important neuro‐immune pathway in the development of hypertension and therefore may serve as a novel therapeutic target for the treatment of neurogenic hypertension. PMID:27230966

Trailing edge flow conditions as a factor in airfoil design

NASA Technical Reports Server (NTRS)

Ormsbee, A. I.; Maughmer, M. D.

1984-01-01

Some new developments relevant to the design of single-element airfoils using potential flow methods are presented. In particular, the role played by the non-dimensional trailing edge velocity in design is considered and the relationship between the specified value and the resulting airfoil geometry is explored. In addition, the ramifications of the unbounded trailing edge pressure gradients generally present in the potential flow solution of the flow over an airfoil are examined, and the conditions necessary to obtain a class of airfoils having finite trailing edge pressure gradients developed. The incorporation of these conditions into the inverse method of Eppler is presented and the modified scheme employed to generate a number of airfoils for consideration. The detailed viscous analysis of airfoils having finite trailing edge pressure gradients demonstrates a reduction in the strong inviscid-viscid interactions generally present near the trailing edge of an airfoil.

Perceived social pressures and the internalization of the mesomorphic ideal: The role of drive for muscularity and autonomy in physically active men.

PubMed

Edwards, Christian; Tod, David; Molnar, Gyozo; Markland, David

2016-03-01

We examined if there were both direct and indirect relationships (via the drive for muscularity) between the perceived pressure to be muscular and internalization of the mesomorphic ideal, and if autonomy moderates these relationships in physically active men. A sample of 330 men, who were undergraduate students studying sport, completed the Behavioral Regulation in Exercise Questionnaire-2, the Mesomorphic Ideal Internalization subscale of the revised male version Sociocultural Attitudes Toward Appearance Questionnaire, the Perceived Sociocultural Pressure Scale-Modified, and the Drive for Muscularity Scale Attitudes subscale. Perceived pressure predicted internalization directly, and indirectly through the drive for muscularity. The direct relationship between pressure and internalization was weaker under higher levels of autonomy. The indirect path, via drive for muscularity, was stronger under higher levels of autonomy. These results provide insights into why men vary in the degree to which they internalize pressure to develop a mesomorphic ideal, supporting further examination of autonomy. Copyright © 2015 Elsevier Ltd. All rights reserved.

Flexible hemispheric microarrays of highly pressure-sensitive sensors based on breath figure method.

PubMed

Wang, Zhihui; Zhang, Ling; Liu, Jin; Jiang, Hao; Li, Chunzhong

2018-05-30

Recently, flexible pressure sensors featuring high sensitivity, broad sensing range and real-time detection have aroused great attention owing to their crucial role in the development of artificial intelligent devices and healthcare systems. Herein, highly sensitive pressure sensors based on hemisphere-microarray flexible substrates are fabricated via inversely templating honeycomb structures deriving from a facile and static breath figure process. The interlocked and subtle microstructures greatly improve the sensing characteristics and compressibility of the as-prepared pressure sensor, endowing it a sensitivity as high as 196 kPa-1 and a wide pressure sensing range (0-100 kPa), as well as other superior performance, including a lower detection limit of 0.5 Pa, fast response time (<26 ms) and high reversibility (>10 000 cycles). Based on the outstanding sensing performance, the potential capability of our pressure sensor in capturing physiological information and recognizing speech signals has been demonstrated, indicating promising application in wearable and intelligent electronics.

The face of appearance-related social pressure: gender, age and body mass variations in peer and parental pressure during adolescence.

PubMed

Helfert, Susanne; Warschburger, Petra

2013-05-17

Appearance-related social pressure plays an important role in the development of a negative body image and self-esteem as well as severe mental disorders during adolescence (e.g. eating disorders, depression). Identifying who is particularly affected by social pressure can improve targeted prevention and intervention, but findings have either been lacking or controversial. Thus the aim of this study is to provide a detailed picture of gender, weight, and age-related variations in the perception of appearance-related social pressure by peers and parents. 1112 German students between grades 7 and 9 (mean age: M = 13.38, SD = .81) filled in the Appearance-Related Social Pressure Questionnaire (German: FASD), which considers different sources (peers, parents) as well as various kinds of social pressure (e.g. teasing, modeling, encouragement). Girls were more affected by peer pressure, while gender differences in parental pressure seemed negligible. Main effects of grade-level suggested a particular increase in indirect peer pressure (e.g. appearance-related school and class norms) from early to middle adolescence. Boys and girls with higher BMI were particularly affected by peer teasing and exclusion as well as by parental encouragement to control weight and shape. The results suggest that preventive efforts targeting body concerns and disordered eating should bring up the topic of appearance pressure in a school-based context and should strengthen those adolescents who are particularly at risk - in our study, girls and adolescents with higher weight status. Early adolescence and school transition appear to be crucial periods for these efforts. Moreover, the comprehensive assessment of appearance-related social pressure appears to be a fruitful way to further explore social risk-factors in the development of a negative body image.

The face of appearance-related social pressure: gender, age and body mass variations in peer and parental pressure during adolescence

PubMed Central

2013-01-01

Background Appearance-related social pressure plays an important role in the development of a negative body image and self-esteem as well as severe mental disorders during adolescence (e.g. eating disorders, depression). Identifying who is particularly affected by social pressure can improve targeted prevention and intervention, but findings have either been lacking or controversial. Thus the aim of this study is to provide a detailed picture of gender, weight, and age-related variations in the perception of appearance-related social pressure by peers and parents. Methods 1112 German students between grades 7 and 9 (mean age: M = 13.38, SD = .81) filled in the Appearance-Related Social Pressure Questionnaire (German: FASD), which considers different sources (peers, parents) as well as various kinds of social pressure (e.g. teasing, modeling, encouragement). Results Girls were more affected by peer pressure, while gender differences in parental pressure seemed negligible. Main effects of grade-level suggested a particular increase in indirect peer pressure (e.g. appearance-related school and class norms) from early to middle adolescence. Boys and girls with higher BMI were particularly affected by peer teasing and exclusion as well as by parental encouragement to control weight and shape. Conclusion The results suggest that preventive efforts targeting body concerns and disordered eating should bring up the topic of appearance pressure in a school-based context and should strengthen those adolescents who are particularly at risk - in our study, girls and adolescents with higher weight status. Early adolescence and school transition appear to be crucial periods for these efforts. Moreover, the comprehensive assessment of appearance-related social pressure appears to be a fruitful way to further explore social risk-factors in the development of a negative body image. PMID:23680225

Virtual Reality, Combat, and Communication.

ERIC Educational Resources Information Center

Thrush, Emily Austin; Bodary, Michael

2000-01-01

Presents a brief examination of the evolution of virtual reality devices that illustrates how the development of this new medium is influenced by emerging technologies and by marketing pressures. Notes that understanding these influences may help prepare for the role of technical communicators in building virtual reality applications for education…

The Teacher as Shaper of Conscience.

ERIC Educational Resources Information Center

Himes, Kenneth

1994-01-01

Discusses the role of conscience in moral decisions and several approaches to moral education. Indicates that moral development is an interactive process between children and their environment and that empathy, delayed gratification, and the courage to withstand social pressure must be encouraged in the moral education of youth. (MAB)

Transferrin Receptor 1 in Chronic Hypoxia-Induced Pulmonary Vascular Remodeling.

PubMed

Naito, Yoshiro; Hosokawa, Manami; Sawada, Hisashi; Oboshi, Makiko; Hirotani, Shinichi; Iwasaku, Toshihiro; Okuhara, Yoshitaka; Morisawa, Daisuke; Eguchi, Akiyo; Nishimura, Koichi; Soyama, Yuko; Fujii, Kenichi; Mano, Toshiaki; Ishihara, Masaharu; Tsujino, Takeshi; Masuyama, Tohru

2016-06-01

Iron is associated with the pathophysiology of several cardiovascular diseases, including pulmonary hypertension (PH). In addition, disrupted pulmonary iron homeostasis has been reported in several chronic lung diseases. Transferrin receptor 1 (TfR1) plays a key role in cellular iron transport. However, the role of TfR1 in the pathophysiology of PH has not been well characterized. In this study, we investigate the role of TfR1 in the development of hypoxia-induced pulmonary vascular remodeling. PH was induced by exposing wild-type (WT) mice and TfR1 hetero knockout mice to hypoxia for 4 weeks and evaluated via assessment of pulmonary vascular remodeling, right ventricular (RV) systolic pressure, and RV hypertrophy. In addition, we assessed the functional role of TfR1 in pulmonary artery smooth muscle cells in vitro. The morphology of pulmonary arteries did not differ between WT mice and TfR1 hetero knockout mice under normoxic conditions. In contrast, TfR1 hetero knockout mice exposed to 4 weeks hypoxia showed attenuated pulmonary vascular remodeling, RV systolic pressure, and RV hypertrophy compared with WT mice. In addition, the depletion of TfR1 by RNA interference attenuated human pulmonary artery smooth muscle cells proliferation induced by platelet-derived growth factor-BB (PDGF-BB) in vitro. These results suggest that TfR1 plays an important role in the development of hypoxia-induced pulmonary vascular remodeling. © American Journal of Hypertension, Ltd 2015. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Is atmospheric pressure change an Independent risk factor for hemoptysis?

PubMed

Araz, Omer; Ucar, Elif Yilmazel; Akgun, Metin; Aydin, Yener; Meral, Mehmet; Saglam, Leyla; Kaynar, Hasan; Gorguner, Ali Metin

2014-05-01

Hemoptysis is one of the most important and challenging symptoms in pulmonary medicine. Because of the increased number of patients with hemoptysis in certain periods of the year, we aimed to investigate whether atmospheric changes have an effect on the development of hemoptysis with or without a secondary cause. The data of patients presenting with hemoptysis between January 2006 and December 2011 were analyzed. Data on the daily atmospheric pressure (hectopascal, hPa), relative humidity (%), and temperature ((o) C) during that time were obtained. A total of 232 patients with hemoptysis, 145 male (62.5%) and 87 female (37.5%) with an average age of 48.1(±17.6), were admitted to our hospital between 2006 and 2011. The highest admission rates were in the spring season, the highest in May (n=37, 15.9%), and the lowest admission rates were in December (n=10, 4.3%). A statistically significant negative correlation was found between the number of hemoptysis cases and mean atmospheric pressure but no relative humidity or outdoor temperature. Hemoptysis is very much influenced by weather factors; in particular, low atmospheric pressures significantly affect the development of hemoptysis. Fluctuations in atmospheric pressure may also play a role in hemoptysis.

A new pressure ulcer conceptual framework.

PubMed

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

2014-10-01

This paper discusses the critical determinants of pressure ulcer development and proposes a new pressure ulcer conceptual framework. Recent work to develop and validate a new evidence-based pressure ulcer risk assessment framework was undertaken. This formed part of a Pressure UlceR Programme Of reSEarch (RP-PG-0407-10056), funded by the National Institute for Health Research. The foundation for the risk assessment component incorporated a systematic review and a consensus study that highlighted the need to propose a new conceptual framework. Discussion Paper. The new conceptual framework links evidence from biomechanical, physiological and epidemiological evidence, through use of data from a systematic review (search conducted March 2010), a consensus study (conducted December 2010-2011) and an international expert group meeting (conducted December 2011). A new pressure ulcer conceptual framework incorporating key physiological and biomechanical components and their impact on internal strains, stresses and damage thresholds is proposed. Direct and key indirect causal factors suggested in a theoretical causal pathway are mapped to the physiological and biomechanical components of the framework. The new proposed conceptual framework provides the basis for understanding the critical determinants of pressure ulcer development and has the potential to influence risk assessment guidance and practice. It could also be used to underpin future research to explore the role of individual risk factors conceptually and operationally. By integrating existing knowledge from epidemiological, physiological and biomechanical evidence, a theoretical causal pathway and new conceptual framework are proposed with potential implications for practice and research. © 2014 The Authors. Journal of Advanced Nursing Published by John Wiley & Sons Ltd.

A new pressure ulcer conceptual framework

PubMed Central

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

2014-01-01

Aim This paper discusses the critical determinants of pressure ulcer development and proposes a new pressure ulcer conceptual framework. Background Recent work to develop and validate a new evidence-based pressure ulcer risk assessment framework was undertaken. This formed part of a Pressure UlceR Programme Of reSEarch (RP-PG-0407-10056), funded by the National Institute for Health Research. The foundation for the risk assessment component incorporated a systematic review and a consensus study that highlighted the need to propose a new conceptual framework. Design Discussion Paper. Data Sources The new conceptual framework links evidence from biomechanical, physiological and epidemiological evidence, through use of data from a systematic review (search conducted March 2010), a consensus study (conducted December 2010–2011) and an international expert group meeting (conducted December 2011). Implications for Nursing A new pressure ulcer conceptual framework incorporating key physiological and biomechanical components and their impact on internal strains, stresses and damage thresholds is proposed. Direct and key indirect causal factors suggested in a theoretical causal pathway are mapped to the physiological and biomechanical components of the framework. The new proposed conceptual framework provides the basis for understanding the critical determinants of pressure ulcer development and has the potential to influence risk assessment guidance and practice. It could also be used to underpin future research to explore the role of individual risk factors conceptually and operationally. Conclusion By integrating existing knowledge from epidemiological, physiological and biomechanical evidence, a theoretical causal pathway and new conceptual framework are proposed with potential implications for practice and research. PMID:24684197

Friends, Foes, and Noncombatants: Notes on Public Education's Pressure Groups.

ERIC Educational Resources Information Center

Kaplan, George R.

2000-01-01

Appraises five major (nonchampioning) forces pressuring public education: the expanding role of business interests; uneven performance of education's own pressure groups; changing role of cultural conservatism; influence of new-breed information providers; and effects of shifting labels and definitions of political loyalty on needy schools. (MLH)

Effects of Hydrostatic Pressure on Carcinogenic Properties of Epithelia.

PubMed

Tokuda, Shinsaku; Kim, Young Hak; Matsumoto, Hisako; Muro, Shigeo; Hirai, Toyohiro; Mishima, Michiaki; Furuse, Mikio

2015-01-01

The relationship between chronic inflammation and cancer is well known. The inflammation increases the permeability of blood vessels and consequently elevates pressure in the interstitial tissues. However, there have been only a few reports on the effects of hydrostatic pressure on cultured cells, and the relationship between elevated hydrostatic pressure and cell properties related to malignant tumors is less well understood. Therefore, we investigated the effects of hydrostatic pressure on the cultured epithelial cells seeded on permeable filters. Surprisingly, hydrostatic pressure from basal to apical side induced epithelial stratification in Madin-Darby canine kidney (MDCK) I and Caco-2 cells, and cavities with microvilli and tight junctions around their surfaces were formed within the multi-layered epithelia. The hydrostatic pressure gradient also promoted cell proliferation, suppressed cell apoptosis, and increased transepithelial ion permeability. The inhibition of protein kinase A (PKA) promoted epithelial stratification by the hydrostatic pressure whereas the activation of PKA led to suppressed epithelial stratification. These results indicate the role of the hydrostatic pressure gradient in the regulation of various epithelial cell functions. The findings in this study may provide clues for the development of a novel strategy for the treatment of the carcinoma.

Effects of Hydrostatic Pressure on Carcinogenic Properties of Epithelia

PubMed Central

Tokuda, Shinsaku; Kim, Young Hak; Matsumoto, Hisako; Muro, Shigeo; Hirai, Toyohiro; Mishima, Michiaki; Furuse, Mikio

2015-01-01

The relationship between chronic inflammation and cancer is well known. The inflammation increases the permeability of blood vessels and consequently elevates pressure in the interstitial tissues. However, there have been only a few reports on the effects of hydrostatic pressure on cultured cells, and the relationship between elevated hydrostatic pressure and cell properties related to malignant tumors is less well understood. Therefore, we investigated the effects of hydrostatic pressure on the cultured epithelial cells seeded on permeable filters. Surprisingly, hydrostatic pressure from basal to apical side induced epithelial stratification in Madin-Darby canine kidney (MDCK) I and Caco-2 cells, and cavities with microvilli and tight junctions around their surfaces were formed within the multi-layered epithelia. The hydrostatic pressure gradient also promoted cell proliferation, suppressed cell apoptosis, and increased transepithelial ion permeability. The inhibition of protein kinase A (PKA) promoted epithelial stratification by the hydrostatic pressure whereas the activation of PKA led to suppressed epithelial stratification. These results indicate the role of the hydrostatic pressure gradient in the regulation of various epithelial cell functions. The findings in this study may provide clues for the development of a novel strategy for the treatment of the carcinoma. PMID:26716691

Continuum model for hydrogen pickup in zirconium alloys of LWR fuel cladding

NASA Astrophysics Data System (ADS)

Wang, Xing; Zheng, Ming-Jie; Szlufarska, Izabela; Morgan, Dane

2017-04-01

A continuum model for calculating the time-dependent hydrogen pickup fractions in various Zirconium alloys under steam and pressured water oxidation has been developed in this study. Using only one fitting parameter, the effective hydrogen gas partial pressure at the oxide surface, a qualitative agreement is obtained between the predicted and previously measured hydrogen pickup fractions. The calculation results therefore demonstrate that H diffusion through the dense oxide layer plays an important role in the hydrogen pickup process. The limitations and possible improvement of the model are also discussed.

Renal inflammation, autoimmunity and salt-sensitive hypertension

PubMed Central

Rodríguez-Iturbe, Bernardo; Franco, Martha; Tapia, Edilia; Quiroz, Yasmir; Johnson, Richard J

2011-01-01

This article reviews the role of immune competent cells infiltrating the kidney and their association with oxidative stress and renal angiotensin activity in the development of salt-sensitive hypertension.We discuss the alteration of the pressure-natriuresis relationship resulting from renal inflammation and its improvement resulting from immunosuppressive treatment.The potential role of T cell-driven reactivity in sustaining the renal inflammation is examined in the light of accumulating evidence of autoimmune mechanisms in experimental and clinical hypertension. PMID:21251049

Air Circulation and Heat Exchange under Reduced Pressures

NASA Astrophysics Data System (ADS)

Rygalov, Vadim; Wheeler, Raymond; Dixon, Mike; Hillhouse, Len; Fowler, Philip

Low pressure atmospheres were suggested for Space Greenhouses (SG) design to minimize sys-tem construction and re-supply materials, as well as system manufacturing and deployment costs. But rarified atmospheres modify heat exchange mechanisms what finally leads to alter-ations in thermal control for low pressure closed environments. Under low atmospheric pressures (e.g., lower than 25 kPa compare to 101.3 kPa for normal Earth atmosphere), convection is becoming replaced by diffusion and rate of heat exchange reduces significantly. During a period from 2001 to 2009, a series of hypobaric experiments were conducted at Space Life Sciences Lab (SLSLab) NASA's Kennedy Space Center and the Department of Space Studies, University of North Dakota. Findings from these experiments showed: -air circulation rate decreases non-linearly with lowering of total atmospheric pressure; -heat exchange slows down with pressure decrease creating risk of thermal stress (elevated leaf tem-peratures) for plants in closed environments; -low pressure-induced thermal stress could be reduced by either lowering system temperature set point or increasing forced convection rates (circulation fan power) within certain limits; Air circulation is an important constituent of controlled environments and plays crucial role in material and heat exchange. Theoretical schematics and mathematical models are developed from a series of observations. These models can be used to establish optimal control algorithms for low pressure environments, such as a space greenhouse, as well as assist in fundamental design concept developments for these or similar habitable structures.

CNS sites activated by renal pelvic epithelial sodium channels (ENaCs) in response to hypertonic saline in awake rats.

PubMed

Goodwill, Vanessa S; Terrill, Christopher; Hopewood, Ian; Loewy, Arthur D; Knuepfer, Mark M

2017-05-01

In some patients, renal nerve denervation has been reported to be an effective treatment for essential hypertension. Considerable evidence suggests that afferent renal nerves (ARN) and sodium balance play important roles in the development and maintenance of high blood pressure. ARN are sensitive to sodium concentrations in the renal pelvis. To better understand the role of ARN, we infused isotonic or hypertonic NaCl (308 or 500mOsm) into the left renal pelvis of conscious rats for two 2hours while recording arterial pressure and heart rate. Subsequently, brain tissue was analyzed for immunohistochemical detection of the protein Fos, a marker for neuronal activation. Fos-immunoreactive neurons were identified in numerous sites in the forebrain and brainstem. These areas included the nucleus tractus solitarius (NTS), the lateral parabrachial nucleus, the paraventricular nucleus of the hypothalamus (PVH) and the supraoptic nucleus (SON). The most effective stimulus was 500mOsm NaCl. Activation of these sites was attenuated or prevented by administration of benzamil (1μM) or amiloride (10μM) into the renal pelvis concomitantly with hypertonic saline. In anesthetized rats, infusion of hypertonic saline but not isotonic saline into the renal pelvis elevated ARN activity and this increase was attenuated by simultaneous infusion of benzamil or amiloride. We propose that renal pelvic epithelial sodium channels (ENaCs) play a role in activation of ARN and, via central visceral afferent circuits, this system modulates fluid volume and peripheral blood pressure. These pathways may contribute to the development of hypertension. Copyright © 2016 Elsevier B.V. All rights reserved.

Superconductivity in highly disordered dense carbon disulfide

PubMed Central

Dias, Ranga P.; Yoo, Choong-Shik; Struzhkin, Viktor V.; Kim, Minseob; Muramatsu, Takaki; Matsuoka, Takahiro; Ohishi, Yasuo; Sinogeikin, Stanislav

2013-01-01

High pressure plays an increasingly important role in both understanding superconductivity and the development of new superconducting materials. New superconductors were found in metallic and metal oxide systems at high pressure. However, because of the filled close-shell configuration, the superconductivity in molecular systems has been limited to charge-transferred salts and metal-doped carbon species with relatively low superconducting transition temperatures. Here, we report the low-temperature superconducting phase observed in diamagnetic carbon disulfide under high pressure. The superconductivity arises from a highly disordered extended state (CS4 phase or phase III[CS4]) at ∼6.2 K over a broad pressure range from 50 to 172 GPa. Based on the X-ray scattering data, we suggest that the local structural change from a tetrahedral to an octahedral configuration is responsible for the observed superconductivity. PMID:23818624

Numerical investigation of cavitation flow inside spool valve with large pressure drop

NASA Astrophysics Data System (ADS)

Deng, Jian; Pan, Dingyi; Xie, Fangfang; Shao, Xueming

2015-12-01

Spool valves play an important role in fluid power system. Cavitation phenomena happen frequently inside the spool valves, which cause structure damages, noise and lower down hydrodynamic performance. A numerical tools incorporating the cavitation model, are developed to predict the flow structure and cavitation pattern in the spool valve. Two major flow states in the spool valve chamber, i.e. flow-in and flow-out, are studies. The pressure distributions along the spool wall are first investigated, and the results agree well with the experimental data. For the flow-in cases, the local pressure at the throttling area drops much deeper than the pressure in flow-out cases. Meanwhile, the bubbles are more stable in flow-in cases than those in flow-out cases, which are ruptured and shed into the downstream.

Curriculum Politics in Higher Education: What Educators Need to Do to Survive

ERIC Educational Resources Information Center

Joseph, Stephen

2015-01-01

Higher education institutions are increasingly experiencing pressure regarding their expected role in addressing immediate and long-term sustainable development challenges. Decisions about what should be taught are heavily influenced by socio-political needs and aspirations. The push towards entrepreneurship education is, perhaps, one example…

Policy Rhetorics and Resource Neutral Reforms in Higher Education: Their Impact and Implications?

ERIC Educational Resources Information Center

Sugrue, Ciaran; Solbrekke, Tone Dyrdal

2017-01-01

As higher education (HE) comes under increasing pressure from policy-makers, nationally and internationally, to contribute more directly to economic development, tensions between more traditional missions of universities and their more recent entrepreneurial makeovers create major dilemmas for academic staff regarding their roles and…

Academic Regulation of EFL in Ireland: Developments since 1991.

ERIC Educational Resources Information Center

Ruane, Mary

1995-01-01

Changes in educational policy concerning the teaching of English as a foreign language (EFL) in Ireland, and events surrounding those changes, are chronicled. The evolution of public agencies and private organizations, including teacher associations, and their roles in effecting change are described. Pressures leading to the formal announcement in…

I Have a Dream: School Principals as Entrepreneurs

ERIC Educational Resources Information Center

Yemini, Miri; Addi-Raccah, Audrey; Katarivas, Keren

2015-01-01

Most policymakers and academics agree that entrepreneurship is indispensable to society's development and well-being. Fostering entrepreneurship has become a matter of highest priority in public policy worldwide. Given the growing pressures of decentralization and competitiveness that schools have faced over the last 20 years, the role of school…

Processing Determinism

ERIC Educational Resources Information Center

O'Grady, William

2015-01-01

I propose that the course of development in first and second language acquisition is shaped by two types of processing pressures--internal efficiency-related factors relevant to easing the burden on working memory and external input-related factors such as frequency of occurrence. In an attempt to document the role of internal factors, I consider…

Practitioner Perspectives on the Use of Technology in Fieldwork Teaching

ERIC Educational Resources Information Center

Fletcher, Stephen; France, Derek; Moore, Kate; Robinson, Geoff

2007-01-01

During the last decade, technological developments in computer hardware, software and networks, combined with increasing pressures on staff and students, have led to a proliferation of Communication and Information Technology (C&IT) within the Geography, Earth and Environmental Sciences (GEES) disciplines. This research investigates the role of…

Role of Affective Self-Regulatory Efficacy in Diverse Spheres of Psychosocial Functioning.

ERIC Educational Resources Information Center

Bandura, Albert; Caprara, Gian Vittorio; Barbaranelli, Claudio; Gerbino, Maria; Pastorelli, Concetta

2003-01-01

Examined influence of perceived self-efficacy for affect regulation with older adolescents. Found that self-efficacy to regulate affect related to high efficacy to manage academic development, resist social pressures for antisocial activities, and engage with empathy in others' emotional experiences. Perceived self-efficacy for affect regulation…

The Role of Communication Technology in Adolescent Relationships and Identity Development

ERIC Educational Resources Information Center

Cyr, Betty-Ann; Berman, Steven L.; Smith, Megan L.

2015-01-01

Background: The popularity of communication technologies such as text messaging, e-mail, instant messaging, and social networking sites has grown exponentially, especially among adolescents. At the scale of growth along with the pressures and normative use of communication technology, psychological effects of these technologies need to be further…

Hydrostatic pressure promotes the proliferation and osteogenic/chondrogenic differentiation of mesenchymal stem cells: The roles of RhoA and Rac1.

PubMed

Zhao, Yin-Hua; Lv, Xin; Liu, Yan-Li; Zhao, Ying; Li, Qiang; Chen, Yong-Jin; Zhang, Min

2015-05-01

Our previous studies have shown that hydrostatic pressure can serve as an active regulator for bone marrow mesenchymal stem cells (BMSCs). The current work further investigates the roles of cytoskeletal regulatory proteins Ras homolog gene family member A (RhoA) and Ras-related C3 botulinum toxin substrate 1 (Rac1) in hydrostatic pressure-related effects on BMSCs. Flow cytometry assays showed that the hydrostatic pressure promoted cell cycle initiation in a RhoA- and Rac1-dependent manner. Furthermore, fluorescence assays confirmed that RhoA played a positive and Rac1 displayed a negative role in the hydrostatic pressure-induced F-actin stress fiber assembly. Western blots suggested that RhoA and Rac1 play central roles in the pressure-inhibited ERK phosphorylation, and Rac1 but not RhoA was involved in the pressure-promoted JNK phosphorylation. Finally, real-time polymerase chain reaction (PCR) experiments showed that pressure promoted the expression of osteogenic marker genes in BMSCs at an early stage of osteogenic differentiation through the up-regulation of RhoA activity. Additionally, the PCR results showed that pressure enhanced the expression of chondrogenic marker genes in BMSCs during chondrogenic differentiation via the up-regulation of Rac1 activity. Collectively, our results suggested that RhoA and Rac1 are critical to the pressure-induced proliferation and differentiation, the stress fiber assembly, and MAPK activation in BMSCs. Copyright © 2015. Published by Elsevier B.V.

A miniature fiber optic pressure sensor for intradiscal pressure measurements of rodents

NASA Astrophysics Data System (ADS)

Nesson, Silas; Yu, Miao; Hsieh, Adam H.

2007-04-01

Lower back pain continues to be a leading cause of disability in people of all ages, and has been associated with degenerative disc disease. It is well accepted that mechanical stress, among other factors, can play a role in the development of disc degeneration. Pressures generated in the intervertebral disc have been measured both in vivo and in vitro for humans and animals. However, thus far it has been difficult to measure pressure experimentally in rodent discs due to their small size. With the prevalent use of rodent tail disc models in mechanobiology, it is important to characterize the intradiscal pressures generated with externally applied stresses. In this paper, a miniature fiber optic Fabry-Perot interferometric pressure sensor with an outer diameter of 360 μm was developed to measure intradiscal pressures in rat caudal discs. A low coherence interferometer based optical system was used, which includes a broadband light source, a high-speed spectrometer, and a Fabry-Perot sensor. The sensor employs a capillary tube, a flexible, polymer diaphragm coated with titanium as a partial mirror, and a fiber tip as another mirror. The pressure induced deformation of the diaphragm results in a cavity length change of the Fabry-Perot interferometer which can be calculated from the wavelength shift of interference fringes. The sensor exhibited good linearity with small applied pressures. Our validation experiments show that owing to the small size, inserting the sensor does not disrupt the annulus fibrosus and will not alter intradiscal pressures generated. Measurements also demonstrate the feasibility of using this sensor to quantify external load intradiscal pressure relationships in small animal discs.

4D pressure MRI: validation through in-vitro experiments and simulations

NASA Astrophysics Data System (ADS)

Schiavazzi, Daniele; Amili, Omid; Coletti, Filippo

2017-11-01

Advances in MRI scan technology and recently developed acquisition sequences have led to the development of 4D flow MRI, a protocol capable of characterizing in-vivo hemodynamics in patients. Thus, the availability of phase-averaged time-resolved three-dimensional blood velocities has opened new opportunities for computing a wide spectrum of totally non-invasive hemodynamic indicators. In this regard, relative pressures play a particularly important role, as they are routinely employed in the clinic to detect cardiovascular abnormalities (e.g., in peripheral artery disease, valve stenosis, hypertension, etc.). In the first part of the talk, we discuss how the relative pressures can be robustly computed through the solution of a pressure Poisson equation and how noise in the velocities affects their estimate. Routine application of these techniques in the clinic, require however a thorough validation on multiple patients/anatomies and systematic comparisons with in-vitro and simulated representations. Thus, the second part of the talk illustrates the use of numerical simulation and in-vitro experimental protocols to validate these indicators with reference to aortic and cerebral vascular anatomies.

The role of electron heat flux in guide-field magnetic reconnection

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

Hesse, Michael; Kuznetsova, Masha; Birn, Joachim

2004-12-01

A combination of analytical theory and particle-in-cell simulations are employed in order to investigate the electron dynamics near and at the site of guide field magnetic reconnection. A detailed analysis of the contributions to the reconnection electric field shows that both bulk inertia and pressure-based quasiviscous processes are important for the electrons. Analytic scaling demonstrates that conventional approximations for the electron pressure tensor behavior in the dissipation region fail, and that heat flux contributions need to be accounted for. Based on the evolution equation of the heat flux three tensor, which is derived in this paper, an approximate form ofmore » the relevant heat flux contributions to the pressure tensor is developed, which reproduces the numerical modeling result reasonably well. Based on this approximation, it is possible to develop a scaling of the electron current layer in the central dissipation region. It is shown that the pressure tensor contributions become important at the scale length defined by the electron Larmor radius in the guide magnetic field.« less

Lung heparan sulfates modulate Kfc during increased vascular pressure: evidence for glycocalyx-mediated mechanotransduction

PubMed Central

Cluff, Mark; Kingston, Joseph; Hill, Denzil; Chen, Haiyan; Hoehne, Soeren; Malleske, Daniel T.; Kaur, Rajwinederjit

2012-01-01

Lung endothelial cells respond to changes in vascular pressure through mechanotransduction pathways that alter barrier function via non-Starling mechanism(s). Components of the endothelial glycocalyx have been shown to participate in mechanotransduction in vitro and in systemic vessels, but the glycocalyx's role in mechanosensing and pulmonary barrier function has not been characterized. Mechanotransduction pathways may represent novel targets for therapeutic intervention during states of elevated pulmonary pressure such as acute heart failure, fluid overload, and mechanical ventilation. Our objective was to assess the effects of increasing vascular pressure on whole lung filtration coefficient (Kfc) and characterize the role of endothelial heparan sulfates in mediating mechanotransduction and associated increases in Kfc. Isolated perfused rat lung preparation was used to measure Kfc in response to changes in vascular pressure in combination with superimposed changes in airway pressure. The roles of heparan sulfates, nitric oxide, and reactive oxygen species were investigated. Increases in capillary pressure altered Kfc in a nonlinear relationship, suggesting non-Starling mechanism(s). nitro-l-arginine methyl ester and heparanase III attenuated the effects of increased capillary pressure on Kfc, demonstrating active mechanotransduction leading to barrier dysfunction. The nitric oxide (NO) donor S-nitrosoglutathione exacerbated pressure-mediated increase in Kfc. Ventilation strategies altered lung NO concentration and the Kfc response to increases in vascular pressure. This is the first study to demonstrate a role for the glycocalyx in whole lung mechanotransduction and has important implications in understanding the regulation of vascular permeability in the context of vascular pressure, fluid status, and ventilation strategies. PMID:22160307

Mechanics of the fast-start: muscle function and the role of intramuscular pressure in the escape behavior of amia calva and polypterus palmas

PubMed

Westneat; Hale; Mchenry; Long

1998-11-01

The fast-start escape response is a rapid, powerful body motion used to generate high accelerations of the body in virtually all fishes. Although the neurobiology and behavior of the fast-start are often studied, the patterns of muscle activity and muscle force production during escape are less well understood. We studied the fast-starts of two basal actinopterygian fishes (Amia calva and Polypterus palmas) to investigate the functional morphology of the fast-start and the role of intramuscular pressure (IMP) in escape behavior. Our goals were to determine whether IMP increases during fast starts, to look for associations between muscle activity and elevated IMP, and to determine the functional role of IMP in the mechanics of the escape response. We simultaneously recorded the kinematics, muscle activity patterns and IMP of four A. calva and three P. palmas during the escape response. Both species generated high IMPs of up to 90 kPa (nearly 1 atmosphere) above ambient during the fast-start. The two species showed similar pressure magnitudes but had significantly different motor patterns and escape performance. Stage 1 of the fast-start was generated by simultaneous contraction of locomotor muscle on both sides of the body, although electromyogram amplitudes on the contralateral (convex) side of the fish were significantly lower than on the ipsilateral (concave) side. Simultaneous recordings of IMP, escape motion and muscle activity suggest that pressure change is caused by the contraction and radial swelling of cone-shaped myomeres. We develop a model of IMP production that incorporates myomere geometry, the concept of constant-volume muscular hydrostats, the relationship between fiber angle and muscle force, and the forces that muscle fibers produce. The timing profile of pressure change, behavior and muscle action indicates that elevated muscle pressure is a mechanism of stiffening the body and functions in force transmission during the escape response.

The Role of the Pressure in the Partial Regularity Theory for Weak Solutions of the Navier-Stokes Equations

NASA Astrophysics Data System (ADS)

Chamorro, Diego; Lemarié-Rieusset, Pierre-Gilles; Mayoufi, Kawther

2018-04-01

We study the role of the pressure in the partial regularity theory for weak solutions of the Navier-Stokes equations. By introducing the notion of dissipative solutions, due to D uchon and R obert (Nonlinearity 13:249-255, 2000), we will provide a generalization of the Caffarelli, Kohn and Nirenberg theory. Our approach sheels new light on the role of the pressure in this theory in connection to Serrin's local regularity criterion.

Dispersal of Giant Molecular Clouds by Photoionization and Radiation Pressure

NASA Astrophysics Data System (ADS)

Kim, Jeong-Gyu; Kim, Woong-Tae; Ostriker, Eve C.

2018-01-01

UV radiation feedback from young massive stars plays a key role in the evolution of giant molecular clouds (GMCs) by forming HII regions and driving their expansion. We present the results of radiation hydrodynamic simulations of star cluster formation in turbulent GMCs, focusing on the effects of photoionization and radiation pressure on regulating the net star formation efficiency (SFE) and lifetime of clouds. We find that the net SFE depends primarily on the initial gas surface density, $\\Sigma_0$, such that the net SFE increases from 4% to 50% as $\\Sigma_0$ increases from $20\\,M_{\\odot}\\,{\\rm pc}^{-2}$ to $1300\\,M_{\\odot}\\,{\\rm pc}^{-2}$. Cloud dispersal occurs within $10\\,{\\rm Myr}$ after the onset of radiation feedback, or within 0.7--4.0 free-fall times that increases with $\\Sigma_0$. Photoionization plays a dominant role in destroying molecular clouds typical of the Milky Way, while radiation pressure takes over in massive, dense clouds. Based on the analysis of mass loss processes by photoevaporation or momentum injection, we develop a semi-analytic model for cloud dispersal and compare it with the numerical results.

Genetic Ablation of Fgf23 or Klotho Does not Modulate Experimental Heart Hypertrophy Induced by Pressure Overload.

PubMed

Slavic, Svetlana; Ford, Kristopher; Modert, Magalie; Becirovic, Amarela; Handschuh, Stephan; Baierl, Andreas; Katica, Nejla; Zeitz, Ute; Erben, Reinhold G; Andrukhova, Olena

2017-09-12

Left ventricular hypertrophy (LVH) ultimately leads to heart failure in conditions of increased cardiac pre- or afterload. The bone-derived phosphaturic and sodium-conserving hormone fibroblast growth factor-23 (FGF23) and its co-receptor Klotho have been implicated in the development of uremic LVH. Using transverse aortic constriction (TAC) in gene-targeted mouse models, we examine the role of Fgf23 and Klotho in cardiac hypertrophy and dysfunction induced by pressure overload. TAC profoundly increases serum intact Fgf23 due to increased cardiac and bony Fgf23 transcription and downregulation of Fgf23 cleavage. Aldosterone receptor blocker spironolactone normalizes serum intact Fgf23 levels after TAC by reducing bony Fgf23 transcription. Notably, genetic Fgf23 or Klotho deficiency does not influence TAC-induced hypertrophic remodelling, LV functional impairment, or LV fibrosis. Despite the profound, aldosterone-mediated increase in circulating intact Fgf23 after TAC, our data do not support an essential role of Fgf23 or Klotho in the pathophysiology of pressure overload-induced cardiac hypertrophy.

Role of infrasound pressure waves in atherosclerotic plaque rupture: a theoretical approach.

PubMed

Tsatsaris, Athanasios; Koukounaris, Efstathios; Motsakos, Theodoros; Perrea, Despina

2007-01-01

To investigate the role of infrasound aortic pressure waves (IPW) in atherosclerotic plaque rupture. Atherosclerotic plaques have been simulated partly, in two dimensions, as being short or long Conical Intersections (CIS), that is to say elliptic, parabolic or hyperbolic surfaces. Consequently, the course and reflection of the generated aortic pressure wave (infrasound domain-less than 20Hz) has been examined around the simulated plaques. The incidence of IPW on plaque surface results both in reflection and "refraction" of the wave. The IPW course within tissue, seems to be enhanced by high Cu-level presence at these areas according to recent evidence (US2003000388213). The "refracted", derived wave travels through plaque tissue and is eventually accumulated to the foci of the respective CIS-plaque geometry. The foci location within or underneath atheroma declares zones where infrasound energy is mostly absorbed. This process, among other mechanisms may contribute to plaque rupture through the development of local hemorrhage and inflammation in foci areas. In future, detection of foci areas and repair (i.e. via Laser Healing Microtechnique) may attenuate atherosclerotic plaque rupture behavior.

Giant voltage-induced deformation of a dielectric elastomer under a constant pressure

NASA Astrophysics Data System (ADS)

Godaba, Hareesh; Foo, Choon Chiang; Zhang, Zhi Qian; Khoo, Boo Cheong; Zhu, Jian

2014-09-01

Dielectric elastomer actuators coupled with liquid have recently been developed as soft pumps, soft lenses, Braille displays, etc. In this paper, we investigate the performance of a dielectric elastomer actuator, which is coupled with water. The experiments demonstrate that the membrane of a dielectric elastomer can achieve a giant voltage-induced area strain of 1165%, when subject to a constant pressure. Both theory and experiment show that the pressure plays an important role in determining the electromechanical behaviour. The experiments also suggest that the dielectric elastomer actuators, when coupled with liquid, may suffer mechanical instability and collapse after a large amount of liquid is enclosed by the membrane. This failure mode needs to be taken into account in designing soft actuators.

Empirical and modeled synoptic cloud climatology of the Arctic Ocean

NASA Technical Reports Server (NTRS)

Barry, R. G.; Newell, J. P.; Schweiger, A.; Crane, R. G.

1986-01-01

A set of cloud cover data were developed for the Arctic during the climatically important spring/early summer transition months. Parallel with the determination of mean monthly cloud conditions, data for different synoptic pressure patterns were also composited as a means of evaluating the role of synoptic variability on Arctic cloud regimes. In order to carry out this analysis, a synoptic classification scheme was developed for the Arctic using an objective typing procedure. A second major objective was to analyze model output of pressure fields and cloud parameters from a control run of the Goddard Institue for Space Studies climate model for the same area and to intercompare the synoptic climatatology of the model with that based on the observational data.

Pressure Measurement Sensor

NASA Technical Reports Server (NTRS)

1997-01-01

FFPI Industries Inc. is the manufacturer of fiber-optic sensors that furnish accurate pressure measurements in internal combustion chambers. Such an assessment can help reduce pollution emitted by these engines. A chief component in the sensor owes its seven year- long development to Lewis Research Center funding to embed optical fibers and sensors in metal parts. NASA support to Texas A&M University played a critical role in developing this fiber optic technology and led to the formation of FFPI Industries and the production of fiber sensor products. The simple, rugged design of the sensor offers the potential for mass production at low cost. Widespread application of the new technology is forseen, from natural gas transmission, oil refining and electrical power generation to rail transport and the petrochemical paper product industry.

Use of negative pressure wound therapy with instillation in the management of cervical necrotizing fasciitis.

PubMed

Frankel, Jonathan K; Rezaee, Rod P; Harvey, Donald J; McBeath, Evan R; Zender, Chad A; Lavertu, Pierre

2015-11-01

Cervical necrotizing fasciitis is an aggressive infection that can be rapidly fatal if aggressive therapies are not initiated early. Negative pressure wound therapy has been established as an effective tool in promoting wound healing, but its use in the acutely infected wound has been avoided because it limits frequent irrigations and standard dressing changes. We discuss a novel application of negative pressure wound therapy with instillation in an immunocompromised patient with extensive cervical necrotizing fasciitis. The negative pressure wound therapy with instillation provided pain relief by minimizing the frequency of dressing changes, increased the speed of healing, helped to control infection, and facilitated the development of a healthy wound bed sufficient for reconstruction with a split thickness skin graft. The role of negative pressure wound therapy with instillation continues to expand and can be used in the management of both acute and chronic wounds in the head and neck. © 2015 Wiley Periodicals, Inc.

The operational stability of a centrifugal compressor and its dependence on the characteristics of the subcomponents

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

Hunziker, R.; Gyarmathy, G.

1994-04-01

A centrifugal compressor was tested with three different diffusers with circular-arc vanes. The vane inlet angle was varied from 15 to 30 deg. Detailed static wall pressure measurements show that the pressure field in the diffuser inlet is very sensitive to flow rate. The stability limit regularly occurred at the flow rate giving the maximum pressure rise for the overall stage. Mild surge arises as a dynamic instability of the compression system. The analysis of the pressure rise characteristic of each individual subcomponent (impeller, diffuser inlet, diffuser channel,...) reveals their contribution to the overall pressure rise. The diffuser channels playmore » an inherently destabilizing role while the impeller and the diffuser inlet are typically stabilizing. The stability limit was mainly determined by a change in the characteristic of the diffuser inlet. Further, the stability limit was found to be independent of the development of inducer-tip recirculation.« less

Examining the accuracy of astrophysical disk simulations with a generalized hydrodynamical test problem [The role of pressure and viscosity in SPH simulations of astrophysical disks

DOE PAGES

Raskin, Cody; Owen, J. Michael

2016-10-24

Here, we discuss a generalization of the classic Keplerian disk test problem allowing for both pressure and rotational support, as a method of testing astrophysical codes incorporating both gravitation and hydrodynamics. We argue for the inclusion of pressure in rotating disk simulations on the grounds that realistic, astrophysical disks exhibit non-negligible pressure support. We then apply this test problem to examine the performance of various smoothed particle hydrodynamics (SPH) methods incorporating a number of improvements proposed over the years to address problems noted in modeling the classical gravitation-only Keplerian disk. We also apply this test to a newly developed extensionmore » of SPH based on reproducing kernels called CRKSPH. Counterintuitively, we find that pressure support worsens the performance of traditional SPH on this problem, causing unphysical collapse away from the steady-state disk solution even more rapidly than the purely gravitational problem, whereas CRKSPH greatly reduces this error.« less

The effect of conflicting pressures on the evolution of division of labor.

PubMed

Goldsby, Heather J; Knoester, David B; Kerr, Benjamin; Ofria, Charles

2014-01-01

Within nature, many groups exhibit division of labor. Individuals in these groups are under seemingly antagonistic pressures to perform the task most directly beneficial to themselves and to potentially perform a less desirable task to ensure the success of the group. Performing experiments to study how these pressures interact in an evolutionary context is challenging with organic systems because of long generation times and difficulties related to group propagation and fine-grained control of within-group and between-group pressures. Here, we use groups of digital organisms (i.e., self-replicating computer programs) to explore how populations respond to antagonistic multilevel selection pressures. Specifically, we impose a within-group pressure to perform a highly-rewarded role and a between-group pressure to perform a diverse suite of roles. Thus, individuals specializing on highly-rewarded roles will have a within-group advantage, but groups of such specialists have a between-group disadvantage. We find that digital groups could evolve to be either single-lineage or multi-lineage, depending on experimental parameters. These group compositions are reminiscent of different kinds of major evolutionary transitions that occur within nature, where either relatives divide labor (fraternal transitions) or multiple different organisms coordinate activities to form a higher-level individual (egalitarian transitions). Regardless of group composition, organisms embraced phenotypic plasticity as a means for genetically similar individuals to perform different roles. Additionally, in multi-lineage groups, organisms from lineages performing highly-rewarded roles also employed reproductive restraint to ensure successful coexistence with organisms from other lineages.

Sex differences in primary hypertension

PubMed Central

2012-01-01

Men have higher blood pressure than women through much of life regardless of race and ethnicity. This is a robust and highly conserved sex difference that it is also observed across species including dogs, rats, mice and chickens and it is found in induced, genetic and transgenic animal models of hypertension. Not only do the differences between the ovarian and testicular hormonal milieu contribute to this sexual dimorphism in blood pressure, the sex chromosomes also play a role in and of themselves. This review primarily focuses on epidemiological studies of blood pressure in men and women and experimental models of hypertension in both sexes. Gaps in current knowledge regarding what underlie male-female differences in blood pressure control are discussed. Elucidating the mechanisms underlying sex differences in hypertension may lead to the development of anti-hypertensives tailored to one's sex and ultimately to improved therapeutic strategies for treating this disease and preventing its devastating consequences. PMID:22417477

Emotional dampening in persons with elevated blood pressure: affect dysregulation and risk for hypertension.

PubMed

McCubbin, James A; Loveless, James P; Graham, Jack G; Hall, Gabrielle A; Bart, Ryan M; Moore, DeWayne D; Merritt, Marcellus M; Lane, Richard D; Thayer, Julian F

2014-02-01

Persons with higher blood pressure have emotional dampening in some contexts. This may reflect interactive changes in central nervous system control of affect and autonomic function in the early stages of hypertension development. The purpose of this study is to determine the independence of cardiovascular emotional dampening from alexithymia to better understand the role of affect dysregulation in blood pressure elevations. Ninety-six normotensives were assessed for resting systolic and diastolic (DBP) blood pressure, recognition of emotions in faces and sentences using the Perception of Affect Task (PAT), alexithymia, anxiety, and defensiveness. Resting DBP significantly predicted PAT emotion recognition accuracy in men after adjustment for age, self-reported affect, and alexithymia. Cardiovascular emotional dampening is independent of alexithymia and affect in men. Dampened emotion recognition could potentially influence interpersonal communication and psychosocial distress, thereby further contributing to BP dysregulation and increased cardiovascular risk.

The Rise and Fall of Modern American Childhood in the Twentieth Century.

ERIC Educational Resources Information Center

Strickland, Charles

1984-01-01

Three factors central to the development of modern attitudes toward childhood are awareness that children and adults differ, the definition of women's primary role as maternal, and the increasingly complex demands made on adults. The combined pressures of feminism and the accessibility of broadcast media are changing these factors significantly.…

Pollution Prevention Case Studies: Implications for Army Institutional Processes

DTIC Science & Technology

1994-06-01

waste (FAMC), Optical Fabrication by switching from glass to Laboratory (OFL) plastiC lens production Fort Lewis FORSCOM Develop installation...Role of Compliance Pressures ...................................................................................... 51 6.8 Waste and Recyclables ...Anny Depot AMC Reduce chromium waste (CCAD) through change in Aluminum coating process Fitzsimmons Anny Medical Center HSC Decrease heavy metal

The Role of Universities in International Response to Pandemic Threats

ERIC Educational Resources Information Center

Chapman, David W.; Errecaborde, Kaylee Myhre

2016-01-01

Faced with increasing pressure to generate more of their own budgets, universities in low and middle income countries are increasingly banding together as country and regional-level networks to bid on and subsequently implement externally funded development projects (a pattern already seen in high income countries). While working as a network may…

Using pressure transient analysis to improve well performance and optimize field development in compartmentalized shelf margin deltaic reservoirs

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

Badgett, K.L.; Crawford, G.E.; Mills, W.H.

1996-12-31

BP Exploration`s Gulf of Mexico group developed procedures to conduct effective well tests on conventional production wells and employed them during the development drilling phase of the Mississippi Canyon 109 (MC109) field. Bottomhole pressure data were recorded during the initial few weeks of production. Typically, a 48 hour pressure buildup survey (surface shut-in) was obtained near the end of data acquisition. Data from these tests were analyzed for completion efficiency, reservoir flow capacity, reservoir heterogeneities, and drainage area. Initially wells were gravel packed for sand control, until buildup interpretations indicated skins greater than 20. Frac packing technology was then employed,more » and an immediate improvement was observed with skins dropping into the teens. Over a period of time frac packs were optimized using the test derived skins as a metric. Analysis of pressure data also played an important role in identifying reservoir compartmentalization. The two major reservoir horizons at MC 109 are interpreted as shelf margin deltas. However, each of these has distinctly different compartmentalization issues. The continuous character of the G Sand made it easier to define the depositional system and investigate reservoir compartmentalization issues using a combination of well log, 3D seismic, static pressure trends, and fluid information. In the more distal deltaic reservoirs of the J Sand however, complications with seismic amplitudes and a less reliable tie between wireline and seismic data required the use of pressure transient analysis to efficiently exploit the reservoir.« less

Care planning for pressure ulcers in hospice: the team effect.

PubMed

Eisenberger, Andrew; Zeleznik, Jomarie

2004-09-01

The standards of care for patients at risk for or with a pressure ulcer in hospitals and nursing homes focus on prevention and ulcer healing using an interdisciplinary approach. Although not a primary hospice condition, pressure ulcers are not uncommon in dying patients. Their management in hospices, particularly the involvement of family caregivers, has not been studied. The objective of this study is to identify the factors that influence care planning for the prevention and treatment of pressure ulcers in hospice patients and develop a taxonomy to use for further study. A telephone survey was conducted with 18 hospice directors of clinical services and 10 direct-care nurses. Descriptive qualitative data analysis using grounded theory was utilized. The following three themes were identified: (1) the primary role of the hospice nurse is an educator rather than a wound care provider; (2) hospice providers perceive the barriers and burdens of family caregiver involvement in pressure ulcer care to be bodily location of the pressure ulcer, unpleasant wound characteristics, fear of causing pain, guilt, and having to acknowledge the dying process when a new pressure ulcer develops; and (3) the "team effect" describes the collaboration between family caregivers and the health care providers to establish individualized achievable goals of care ranging from pressure ulcer prevention to acceptance of a pressure ulcer and symptom palliation. Pressure ulcer care planning is a model of collaborative decision making between family caregivers and hospice providers for a condition that occurs as a secondary condition in hospice. A pressure ulcer places significant burdens on family caregivers distinct from common end-of-life symptoms whose treatment is directed at the patient. Because the goals of pressure ulcer care appear to be individualized for a dying patient and their caregivers, the basis of quality-of-care evaluations should be the process of care rather than the outcome of an incident pressure ulcer.

Advanced PIC-MCC simulation for the investigation of step-ionization effect in intermediate-pressure capacitively coupled plasmas

NASA Astrophysics Data System (ADS)

Kim, Jin Seok; Hur, Min Young; Kim, Chang Ho; Kim, Ho Jun; Lee, Hae June

2018-03-01

A two-dimensional parallelized particle-in-cell simulation has been developed to simulate a capacitively coupled plasma reactor. The parallelization using graphics processing units is applied to resolve the heavy computational load. It is found that the step-ionization plays an important role in the intermediate gas pressure of a few Torr. Without the step-ionization, the average electron density decreases while the effective electron temperature increases with the increase of gas pressure at a fixed power. With the step-ionization, however, the average electron density increases while the effective electron temperature decreases with the increase of gas pressure. The cases with the step-ionization agree well with the tendency of experimental measurement. The electron energy distribution functions show that the population of electrons having intermediate energy from 4.2 to 12 eV is relaxed by the step-ionization. Also, it was observed that the power consumption by the electrons is increasing with the increase of gas pressure by the step-ionization process, while the power consumption by the ions decreases with the increase of gas pressure.

Inflight thermodynamic properties

NASA Technical Reports Server (NTRS)

Brown, S. C.; Daniels, G. E.; Johnson, D. L.; Smith, O. E.

1973-01-01

The inflight thermodynamic parameters (temperature, pressure, and density) of the atmosphere are presented. Mean and extreme values of the thermodynamic parameters given here can be used in application of many aerospace problems, such as: (1) research and planning and engineering design of remote earth sensing systems; (2) vehicle design and development; and (3) vehicle trajectory analysis, dealing with vehicle thrust, dynamic pressure, aerodynamic drag, aerodynamic heating, vibration, structural and guidance limitations, and reentry analysis. Atmospheric density plays a very important role in most of the above problems. A subsection on reentry is presented, giving atmospheric models to be used for reentry heating, trajectory, etc., analysis.

The renal compartment: a hydraulic view.

PubMed

Cruces, Pablo; Salas, Camila; Lillo, Pablo; Salomon, Tatiana; Lillo, Felipe; Hurtado, Daniel E

2014-12-01

The hydraulic behavior of the renal compartment is poorly understood. In particular, the role of the renal capsule on the intrarenal pressure has not been thoroughly addressed to date. We hypothesized that pressure and volume in the renal compartment are not linearly related, similar to other body compartments. The pressure-volume curve of the renal compartment was obtained by injecting fluid into the renal pelvis and recording the rise in intrarenal pressure in six anesthetized and mechanically ventilated piglets, using a catheter Camino 4B® inserted into the renal parenchyma. In healthy kidneys, pressure has a highly nonlinear dependence on the injected volume, as revealed by an exponential fit to the data (R (2) = 0.92). On the contrary, a linear relation between pressure and volume is observed in decapsulated kidneys. We propose a biomechanical model for the renal capsule that is able to explain the nonlinear pressure-volume dependence for moderate volume increases. We have presented experimental evidence and a theoretical model that supports the existence of a renal compartment. The mechanical role of the renal capsule investigated in this work may have important implications in elucidating the role of decompressive capsulotomy in reducing the intrarenal pressure in acutely injured kidneys.

Begabung, Leistung Und Geschlecht: Neue Dimensionen Im Lichte Eines Alten Erziehungswissenschaftlichen Diskurses

NASA Astrophysics Data System (ADS)

Stamm, Margrit

2007-07-01

GIFTEDNESS, ACHIEVEMENT AND GENDER - This article deals with the interrelation of giftedness, achievement and gender. It examines the effect of gender affiliation on the development of talent. The cardinal focus is put on the questions of how gender roles influence the lives of gifted children and adolescents as well as what kinds of coping strategies they use to manage these challenges. Based on the thesis stating that the present assimilation of gender roles displays a new challenge of social pressure girls and boys deal with in different ways, the hitherto accessible research findings are discussed in respect of the current state of knowledge. As a result, the existence of the gender gap can be reaffirmed and linked to distinct danger zones for boys and girls. The way into underachievement can be one strategy to get rid of this social pressure.

XEN glaucoma treatment system in the management of refractory glaucomas: a short review on trial data and potential role in clinical practice.

PubMed

De Gregorio, A; Pedrotti, E; Stevan, G; Bertoncello, A; Morselli, S

2018-01-01

The recent development of new devices that are significantly less invasive, collectively termed minimally invasive glaucoma surgery, offers new perspective of intraocular pressure reduction with less risk, short operating times, and rapid recovery. The aim of this work is to provide a panoramic review of the currently published clinical data to assess the potential role of XEN gel stent (Allergan PLC, Irvine, CA, USA) in the management of glaucoma, which is the only filtering minimally invasive glaucoma surgery device that allows the subconjunctival filtration. The ab interno placement of the XEN gel stent offers an alternative for lowering intraocular pressure in refractory glaucoma as a final step, and in patients intolerant to medical therapy as an early surgical approach with minimum conjunctival tissue disruption, restricted flow to avoid hypotony, and long-term safety.

XEN glaucoma treatment system in the management of refractory glaucomas: a short review on trial data and potential role in clinical practice

PubMed Central

De Gregorio, A; Pedrotti, E; Stevan, G; Bertoncello, A; Morselli, S

2018-01-01

The recent development of new devices that are significantly less invasive, collectively termed minimally invasive glaucoma surgery, offers new perspective of intraocular pressure reduction with less risk, short operating times, and rapid recovery. The aim of this work is to provide a panoramic review of the currently published clinical data to assess the potential role of XEN gel stent (Allergan PLC, Irvine, CA, USA) in the management of glaucoma, which is the only filtering minimally invasive glaucoma surgery device that allows the subconjunctival filtration. The ab interno placement of the XEN gel stent offers an alternative for lowering intraocular pressure in refractory glaucoma as a final step, and in patients intolerant to medical therapy as an early surgical approach with minimum conjunctival tissue disruption, restricted flow to avoid hypotony, and long-term safety. PMID:29750009

High pressure phase transformations revisited

NASA Astrophysics Data System (ADS)

Levitas, Valery I.

2018-04-01

High pressure phase transformations play an important role in the search for new materials and material synthesis, as well as in geophysics. However, they are poorly characterized, and phase transformation pressure and pressure hysteresis vary drastically in experiments of different researchers, with different pressure transmitting media, and with different material suppliers. Here we review the current state, challenges in studying phase transformations under high pressure, and the possible ways in overcoming the challenges. This field is critically compared with fields of phase transformations under normal pressure in steels and shape memory alloys, as well as plastic deformation of materials. The main reason for the above mentioned discrepancy is the lack of understanding that there is a fundamental difference between pressure-induced transformations under hydrostatic conditions, stress-induced transformations under nonhydrostatic conditions below yield, and strain-induced transformations during plastic flow. Each of these types of transformations has different mechanisms and requires a completely different thermodynamic and kinetic description and experimental characterization. In comparison with other fields the following challenges are indicated for high pressure phase transformation: (a) initial and evolving microstructure is not included in characterization of transformations; (b) continuum theory is poorly developed; (c) heterogeneous stress and strain fields in experiments are not determined, which leads to confusing material transformational properties with a system behavior. Some ways to advance the field of high pressure phase transformations are suggested. The key points are: (a) to take into account plastic deformations and microstructure evolution during transformations; (b) to formulate phase transformation criteria and kinetic equations in terms of stress and plastic strain tensors (instead of pressure alone); (c) to develop multiscale continuum theories, and (d) to couple experimental, theoretical, and computational studies of the behavior of a tested sample to extract information about fields of stress and strain tensors and concentration of high pressure phase, transformation criteria and kinetics. The ideal characterization should contain complete information which is required for simulation of the same experiments.

High pressure phase transformations revisited.

PubMed

Levitas, Valery I

2018-04-25

High pressure phase transformations play an important role in the search for new materials and material synthesis, as well as in geophysics. However, they are poorly characterized, and phase transformation pressure and pressure hysteresis vary drastically in experiments of different researchers, with different pressure transmitting media, and with different material suppliers. Here we review the current state, challenges in studying phase transformations under high pressure, and the possible ways in overcoming the challenges. This field is critically compared with fields of phase transformations under normal pressure in steels and shape memory alloys, as well as plastic deformation of materials. The main reason for the above mentioned discrepancy is the lack of understanding that there is a fundamental difference between pressure-induced transformations under hydrostatic conditions, stress-induced transformations under nonhydrostatic conditions below yield, and strain-induced transformations during plastic flow. Each of these types of transformations has different mechanisms and requires a completely different thermodynamic and kinetic description and experimental characterization. In comparison with other fields the following challenges are indicated for high pressure phase transformation: (a) initial and evolving microstructure is not included in characterization of transformations; (b) continuum theory is poorly developed; (c) heterogeneous stress and strain fields in experiments are not determined, which leads to confusing material transformational properties with a system behavior. Some ways to advance the field of high pressure phase transformations are suggested. The key points are: (a) to take into account plastic deformations and microstructure evolution during transformations; (b) to formulate phase transformation criteria and kinetic equations in terms of stress and plastic strain tensors (instead of pressure alone); (c) to develop multiscale continuum theories, and (d) to couple experimental, theoretical, and computational studies of the behavior of a tested sample to extract information about fields of stress and strain tensors and concentration of high pressure phase, transformation criteria and kinetics. The ideal characterization should contain complete information which is required for simulation of the same experiments.

Salt Sensitivity and Hypertension: A Paradigm Shift from Kidney Malfunction to Vascular Endothelial Dysfunction

PubMed Central

Choi, Hoon Young; Park, Hyeong Cheon

2015-01-01

Hypertension is a complex trait determined by both genetic and environmental factors and is a major public health problem due to its high prevalence and concomitant increase in the risk for cardiovascular disease. With the recent large increase of dietary salt intake in most developed countries, the prevalence of hypertension increases tremendously which is about 30% of the world population. There is substantial evidence that suggests some people can effectively excrete high dietary salt intake without an increase in arterial BP, and another people cannot excrete effectively without an increase in arterial BP. Salt sensitivity of BP refers to the BP responses for changes in dietary salt intake to produce meaningful BP increases or decreases. The underlying mechanisms that promote salt sensitivity are complex and range from genetic to environmental influences. The phenotype of salt sensitivity is therefore heterogeneous with multiple mechanisms that potentially link high salt intake to increases in blood pressure. Moreover, excess salt intake has functional and pathological effects on the vasculature that are independent of blood pressure. Epidemiologic data demonstrate the role of high dietary salt intake in mediating cardiovascular and renal morbidity and mortality. Almost five decades ago, Guyton and Coleman proposed that whenever arterial pressure is elevated, pressure natriuresis enhances the excretion of sodium and water until blood volume is reduced sufficiently to return arterial pressure to control values. According to this hypothesis, hypertension can develop only when something impairs the excretory ability of sodium in the kidney. However, recent studies suggest that nonosmotic salt accumulation in the skin interstitium and the endothelial dysfunction which might be caused by the deterioration of vascular endothelial glycocalyx layer (EGL) and the epithelial sodium channel on the endothelial luminal surface (EnNaC) also play an important role in nonosmotic storage of salt. These new concepts emphasize that sodium homeostasis and salt sensitivity seem to be related not only to the kidney malfunction but also to the endothelial dysfunction. Further investigations will be needed to assess the extent to which changes in the sodium buffering capacity of the skin interstitium and develop the treatment strategy for modulating the endothelial dysfunction. PMID:26240595

The Effect of Conflicting Pressures on the Evolution of Division of Labor

PubMed Central

Goldsby, Heather J.; Knoester, David B.; Kerr, Benjamin; Ofria, Charles

2014-01-01

Within nature, many groups exhibit division of labor. Individuals in these groups are under seemingly antagonistic pressures to perform the task most directly beneficial to themselves and to potentially perform a less desirable task to ensure the success of the group. Performing experiments to study how these pressures interact in an evolutionary context is challenging with organic systems because of long generation times and difficulties related to group propagation and fine-grained control of within-group and between-group pressures. Here, we use groups of digital organisms (i.e., self-replicating computer programs) to explore how populations respond to antagonistic multilevel selection pressures. Specifically, we impose a within-group pressure to perform a highly-rewarded role and a between-group pressure to perform a diverse suite of roles. Thus, individuals specializing on highly-rewarded roles will have a within-group advantage, but groups of such specialists have a between-group disadvantage. We find that digital groups could evolve to be either single-lineage or multi-lineage, depending on experimental parameters. These group compositions are reminiscent of different kinds of major evolutionary transitions that occur within nature, where either relatives divide labor (fraternal transitions) or multiple different organisms coordinate activities to form a higher-level individual (egalitarian transitions). Regardless of group composition, organisms embraced phenotypic plasticity as a means for genetically similar individuals to perform different roles. Additionally, in multi-lineage groups, organisms from lineages performing highly-rewarded roles also employed reproductive restraint to ensure successful coexistence with organisms from other lineages. PMID:25093399

Work and Mexican American Parent-Adolescent Relationships: The Mediating Role of Parent Well-Being

PubMed Central

Wheeler, Lorey A.; Updegraff, Kimberly A.

2011-01-01

This study of Mexican American two-parent families (N = 246) examined the role of parents’ well-being (i.e., depressive symptoms, role overload) as a potential mechanism through which parent occupational conditions (i.e., self-direction, hazardous conditions, physical activity, work pressure) are linked to parent-adolescent relationship qualities (i.e., warmth, conflict, disclosure). Depressive symptoms mediated the links between maternal and paternal work pressure and parent-adolescent warmth, conflict, and disclosure. For mothers, depressive symptoms also mediated the links between self-direction and mother-adolescent warmth, conflict, and disclosure; for fathers, role overload mediated the links between work pressure and hazardous conditions with father-adolescent warmth. PMID:21355651

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

3D modeling of unconstrained HPT process: role of strain gradient on high deformed microstructure formation

NASA Astrophysics Data System (ADS)

Ben Kaabar, A.; Aoufi, A.; Descartes, S.; Desrayaud, C.

2017-05-01

During tribological contact’s life, different deformation paths lead to the formation of high deformed microstructure, in the near-surface layers of the bodies. The mechanical conditions (high pressure, shear) occurring under contact, are reproduced through unconstrained High Pressure Torsion configuration. A 3D finite element model of this HPT test is developed to study the local deformation history leading to high deformed microstructure with nominal pressure and friction coefficient. For the present numerical study the friction coefficient at the interface sample/anvils is kept constant at 0.3; the material used is high purity iron. The strain distribution in the sample bulk, as well as the main components of the strain gradients according to the spatial coordinates are investigated, with rotation angle of the anvil.

IQGAP1 regulates ERK1/2 and AKT signalling in the heart and sustains functional remodelling upon pressure overload

PubMed Central

Sbroggiò, Mauro; Carnevale, Daniela; Bertero, Alessandro; Cifelli, Giuseppe; De Blasio, Emanuele; Mascio, Giada; Hirsch, Emilio; Bahou, Wadie F.; Turco, Emilia; Silengo, Lorenzo; Brancaccio, Mara; Lembo, Giuseppe; Tarone, Guido

2011-01-01

Aims The Raf-MEK1/2-ERK1/2 (ERK1/2—extracellular signal-regulated kinases 1/2) signalling cascade is crucial in triggering cardiac responses to different stress stimuli. Scaffold proteins are key elements in coordinating signalling molecules for their appropriate spatiotemporal activation. Here, we investigated the role of IQ motif-containing GTPase-activating protein 1 (IQGAP1), a scaffold for the ERK1/2 cascade, in heart function and remodelling in response to pressure overload. Methods and results IQGAP1-null mice have unaltered basal heart function. When subjected to pressure overload, IQGAP1-null mice initially develop a compensatory hypertrophy indistinguishable from that of wild-type (WT) mice. However, upon a prolonged stimulus, the hypertrophic response develops towards a thinning of left ventricular walls, chamber dilation, and a decrease in contractility, in an accelerated fashion compared with WT mice. This unfavourable cardiac remodelling is characterized by blunted reactivation of the foetal gene programme, impaired cardiomyocyte hypertrophy, and increased cardiomyocyte apoptosis. Analysis of signalling pathways revealed two temporally distinct waves of both ERK1/2 and AKT phosphorylation peaking, respectively, at 10 min and 4 days after aortic banding in WT hearts. IQGAP1-null mice show strongly impaired phosphorylation of MEK1/2-ERK1/2 and AKT following 4 days of pressure overload, but normal activation of these kinases after 10 min. Pull-down experiments indicated that IQGAP1 is able to bind the three components of the ERK cascade, namely c-Raf, MEK1/2, and ERK1/2, as well as AKT in the heart. Conclusion These data demonstrate, for the first time, a key role for the scaffold protein IQGAP1 in integrating hypertrophy and survival signals in the heart and regulating long-term left ventricle remodelling upon pressure overload. PMID:21493702

Both cardiomyocyte and endothelial cell Nox4 mediate protection against hemodynamic overload-induced remodelling.

PubMed

Zhang, Min; Mongue-Din, Heloise; Martin, Daniel; Catibog, Norman; Smyrnias, Ioannis; Zhang, Xiaohong; Yu, Bin; Wang, Minshu; Brandes, Ralf P; Schröder, Katrin; Shah, Ajay M

2018-03-01

NADPH oxidase-4 (Nox4) is an important reactive oxygen species (ROS) source that is upregulated in the haemodynamically overloaded heart. Our previous studies using global Nox4 knockout (Nox4KO) mice demonstrated a protective role of Nox4 during chronic abdominal aortic banding, involving a paracrine enhancement of myocardial capillary density. However, other authors who studied cardiac-specific Nox4KO mice reported detrimental effects of Nox4 in response to transverse aortic constriction (TAC). It has been speculated that these divergent results are due to cell-specific actions of Nox4 (i.e. cardiomyocyte Nox4 detrimental but endothelial Nox4 beneficial) and/or differences in the model of pressure overload (i.e. abdominal banding vs. TAC). This study aimed to (i) investigate whether the effects of Nox4 on pressure overload-induced cardiac remodelling vary according to the pressure overload model and (ii) compare the roles of cardiomyocyte vs. endothelial cell Nox4. Global Nox4KO mice subjected to TAC developed worse cardiac remodelling and contractile dysfunction than wild-type littermates, consistent with our previous results with abdominal aortic banding. Next, we generated inducible cardiomyocyte-specific Nox4 KO mice (Cardio-Nox4KO) and endothelial-specific Nox4 KO mice (Endo-Nox4KO) and studied their responses to pressure overload. Both Cardio-Nox4KO and Endo-Nox4KO developed worse pressure overload-induced cardiac remodelling and dysfunction than wild-type littermates, associated with significant decrease in protein levels of HIF1α and VEGF and impairment of myocardial capillarization. Cardiomyocyte as well as endothelial cell Nox4 contributes to protection against chronic hemodynamic overload-induced cardiac remodelling, at least in part through common effects on myocardial capillary density. © The Author 2017 Published by Oxford University Press on behalf of the European Society of Cardiology.

Direct and indirect effects of multiple stressors on stream invertebrates across watershed, reach and site scales: A structural equation modelling better informing on hydromorphological impacts.

PubMed

Villeneuve, B; Piffady, J; Valette, L; Souchon, Y; Usseglio-Polatera, P

2018-01-15

The purpose of our approach was to take into account the nested spatial scales driving stream functioning in the description of pressures/ecological status links by analysing the results of a hierarchical model. The development of this model has allowed us to answer the following questions: Does the consideration of the indirect links between anthropogenic pressures and stream ecological status modify the hierarchy of pressure types impacting benthic invertebrates? Do the different nested scales play different roles in the anthropogenic pressures/ecological status relationship? Does this model lead to better understanding of the specific role of hydromorphology in the evaluation of stream ecological status? To achieve that goal, we used the Partial Least Square (PLS) path modelling method to develop a structural model linking variables describing (i) land use and hydromorphological alterations at the watershed scale, (ii) hydromorphological alterations at the reach scale, (iii) nutrients-organic matter contamination levels at the site scale, and (iv) substrate characteristics at the sampling site scale, to explain variation in values of a macroinvertebrate-based multimetric index: the French I 2 M 2 . We have highlighted the importance of land use effects exerted on both hydromorphological and chemical characteristics of streams observed at finer scales and their subsequent indirect impact on stream ecological status. Hydromorphological alterations have an effect on the substrate mosaic structure and on the concentrations of nutrients and organic matter at site scale. This result implies that stream hydromorphology can have a major indirect effect on macroinvertebrate assemblages and that the hierarchy of impacts of anthropogenic pressures on stream ecological status generally described in the literature - often determining strategic restoration priorities - has to be re-examined. Finally, the effects of nutrients and organic matter on macroinvertebrate assemblages are lower than expected when all the indirect effects of land use and hydromorphological alterations are taken into account. Copyright © 2017 Elsevier B.V. All rights reserved.

Intracellular Pressure Dynamics in Blebbing Cells

PubMed Central

Strychalski, Wanda; Guy, Robert D.

2016-01-01

Blebs are pressure-driven protrusions that play an important role in cell migration, particularly in three-dimensional environments. A bleb is initiated when the cytoskeleton detaches from the cell membrane, resulting in the pressure-driven flow of cytosol toward the area of detachment and local expansion of the cell membrane. Recent experiments involving blebbing cells have led to conflicting hypotheses regarding the timescale of intracellular pressure propagation. The interpretation of one set of experiments supports a poroelastic model of the cytoplasm that leads to slow pressure equilibration when compared to the timescale of bleb expansion. A different study concludes that pressure equilibrates faster than the timescale of bleb expansion. To address this discrepancy, a dynamic computational model of the cell was developed that includes mechanics of and the interactions among the cytoplasm, the actin cortex, the cell membrane, and the cytoskeleton. The model results quantify the relationship among cytoplasmic rheology, pressure, and bleb expansion dynamics, and provide a more detailed picture of intracellular pressure dynamics. This study shows the elastic response of the cytoplasm relieves pressure and limits bleb size, and that both permeability and elasticity of the cytoplasm determine bleb expansion time. Our model with a poroelastic cytoplasm shows that pressure disturbances from bleb initiation propagate faster than the timescale of bleb expansion and that pressure equilibrates slower than the timescale of bleb expansion. The multiple timescales in intracellular pressure dynamics explain the apparent discrepancy in the interpretation of experimental results. PMID:26958893

Desks, Dollars, and Deficits: Managing a Middle School during a Recession.

ERIC Educational Resources Information Center

Merrill, Adeline B.

1992-01-01

A brief history of East Ridge Middle School in Connecticut illustrates the strong economic and demographic pressures that can work against a middle school. The principal plays a crucial role in preserving both the structure and the programs of an effective middle school. Points out strategies to protect and develop middle schools in tough economic…

The Role of Negotiations in the Equation "Declining School Enrollment=Layoffs": A Management Perspective

ERIC Educational Resources Information Center

Spenla, William A.; And Others

1978-01-01

Discusses economic and legal issues related to declining public school enrollments and pressures for "reduction in force" (RIF) of teachers. Reviews developments involving RIF cases in New Jersey and Yonkers, New York. Recommends school boards not agree to contracts that limit their ability to lay off personnel for economic reasons. (JG)

New Partnerships for Learning: Teachers' Perspectives on Their Developing Professional Relationships with Teaching Assistants in England

ERIC Educational Resources Information Center

Bedford, Dorothy; Jackson, Coleen R.; Wilson, Elizabeth

2008-01-01

Over recent decades there has been pressure on schools and teachers, in England, to transform teachers' working practice by advocating an improved role for teaching assistants. In reforming the workforce, the government also intended to support schools in building the momentum for change, whilst raising standards of pupil achievement and enhancing…

The Governance of Curriculum. 1994 Yearbook of the Association for Supervision and Curriculum Development.

ERIC Educational Resources Information Center

Elmore, Richard F., Ed.; Fuhrman, Susan H., Ed.

The United States is moving toward a more national, performance-based view of curriculum policy. The federal government will play a modest role in nationalizing curriculum policy issues, largely by pressuring states and localities through national standards. The chief agents of nationalization will continue to be state and locally based…

Live Action Role Play and the Development of Teacher Competences: Evaluation of "Everyday Life in the Classroom"

ERIC Educational Resources Information Center

Imhof, Margarete; Starker, Ulrike; Spaude, Elena

2016-01-01

Building on Dörner's (1996) theory of complex problem-solving, a learning scenario for teacher students was created and tested. Classroom management is interpreted as a complex problem, which requires the integration of competing interests and tackling multiple, simultaneous tasks under time pressure and with limited information. In addition,…

Grandparental education, parental education and adolescent blood pressure.

PubMed

Kwok, Man Ki; Schooling, C Mary; Leung, Gabriel M; Subramanian, Subu V

2016-09-01

Maternal and paternal education could affect childhood blood pressure differently. Grandparental education might also play a role. Disentangling their contribution to childhood blood pressure may shed light on the persistence of disparities and potential windows of intervention. Using 5604 participants from a Chinese birth cohort born in 1997 and followed-up until ~13years (68% of follow-up), we examined the associations of parental education and grandparental education with age-, sex, and height-specific blood pressure z-scores or prehypertension status. Parental education was inversely associated with adolescent systolic (-0.11 z-score, equivalent to -1.17mmHg, 95% confidence interval (CI) -0.19 to -0.04 for grade ≥12 compared with grade ≤9) and diastolic blood pressure (-0.07 z-score, equivalent to -0.79mmHg, 95% CI -0.11 to -0.04). The magnitude of association was similar for maternal or paternal education. Grandparental education was not associated with adolescent blood pressure. No association with prehypertension was found. In an economically developed non-Western setting, both maternal and paternal, but not grandparental, education was associated with adolescent blood pressure. Blood pressure may be responsive to contemporary family socioeconomic conditions that may be scrutinized for suitable interventions. Copyright © 2016. Published by Elsevier Inc.

NADPH oxidase: an enzyme for multicellularity?

PubMed

Lalucque, Hervé; Silar, Philippe

2003-01-01

Multicellularity has evolved several times during the evolution of eukaryotes. One evolutionary pressure that permits multicellularity relates to the division of work, where one group of cells functions as nutrient providers and the other in specialized roles such as defence or reproduction. This requires signalling systems to ensure harmonious development of multicellular structures. Here, we show that NADPH oxidases are specifically present in organisms that differentiate multicellular structures during their life cycle and are absent from unicellular life forms. The biochemical properties of these enzymes make them ideal candidates for a role in intercellular signalling.

Hypertension and obstructive sleep apnea

PubMed Central

Phillips, Craig L; O’Driscoll, Denise M

2013-01-01

Obstructive sleep apnea (OSA) is increasingly being recognized as a major health burden with strong focus on the associated cardiovascular risk. Studies from the last two decades have provided strong evidence for a causal role of OSA in the development of systemic hypertension. The acute physiological changes that occur during apnea promote nocturnal hypertension and may lead to the development of sustained daytime hypertension via the pathways of sympathetic activation, inflammation, oxidative stress, and endothelial dysfunction. This review will focus on the acute hemodynamic disturbances and associated intermittent hypoxia that characterize OSA and the potential pathophysiological mechanisms responsible for the development of hypertension in OSA. In addition the epidemiology of OSA and hypertension, as well as the role of treatment of OSA, in improving blood pressure control will be examined. PMID:23750107

Intracranial Pressure and Its Relationship to Glaucoma: Current Understanding and Future Directions

PubMed Central

ROY CHOWDHURY, Uttio; FAUTSCH, Michael P.

2015-01-01

Retrospective and prospective studies looking at the role of cerebrospinal fluid pressure (CSFP)/intracranial pressure (ICP) have stimulated new theories and hypotheses regarding the underlying causal events for glaucoma. Most recently, studies supporting a low CSFP/ICP as a risk factor for glaucoma have been published. This review summarizes the current understanding of CSFP/ICP and its potential role in the pathogenicity of the disease. PMID:27350948

Peer influence on gender identity development in adolescence.

PubMed

Kornienko, Olga; Santos, Carlos E; Martin, Carol Lynn; Granger, Kristen L

2016-10-01

During adolescence, gender identity (GI) develops through a dialectic process of personal reflection and with input from the social environment. Peers play an important role in the socialization of gendered behavior, but no studies to-date have assessed peer influences on GI. Thus, the goal of the present study was to examine peer influences on four aspects of adolescents' GI in racially and ethnically diverse 7th- and 8th-grade students (N = 670; 49.5% boys, M age = 12.64) using a longitudinal social network modeling approach. We hypothesized stronger peer influence effects on between-gender dimensions of GI (intergroup bias and felt pressure for gender conformity) than on within-gender dimensions of GI (typicality and contentedness). Consistent with expectations, we found significant peer influence on between-gender components of GI-intergroup bias among 7th and 8th graders as well as felt pressure for gender conformity among 8th graders. In contrast, within-gender components of GI showed no evidence of peer influence. Importantly, these peer socialization effects were evident even when controlling for tendencies to select friends who were similar on gender, gender typicality, and contentedness (8th graders only). Employing longitudinal social network analyses provides insights into and clarity about the roles of peers in gender development. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Antioxidant enzyme activity is associated with blood pressure and carotid intima media thickness in black men and women: The SABPA study.

PubMed

van Zyl, Caitlynd; Huisman, Hugo W; Mels, Catharina M C

2016-05-01

In the urbanized black population of South Africa, oxidative stress may play a crucial role in the development of hypertension. Since oxidative stress may result from impaired antioxidant capacity we aimed to investigate antioxidant enzyme activity as well as its associations with vascular function and structure in a bi-ethnic population. Participants included 409 subjects almost equally stratified by ethnicity and sex. Blood pressure and carotid intima media thickness (cIMT) were measured and glutathione peroxidase (GPx), glutathione reductase (GR), superoxide dismutase (SOD) and catalase (CAT) enzyme activities were determined. GR activity was significantly higher in black men (7.71 nmol/min/ml vs 2.23 nmol/min/ml) and women (6.46 nmol/min/ml vs 2.86 nmol/min/ml) (p < 0.001) when compared to their white counterparts. In black women, GPx activity was significantly lower (p < 0.001) when compared to white women (31.9 nmol/min/ml vs 37.1 nmol/min/ml). In black men, cIMT was positively and independently associated with GR activity (R(2) = 0.30; β = 0.18; p = 0.048). In black women, systolic blood pressure (R(2) = 0.21; β = -0.24; p = 0.014), diastolic blood pressure (R(2) = 0.11; β = -0.20; p = 0.044) and mean arterial pressure (R(2) = 0.20; β = -0.31; p = 0.002) were inversely associated with GPx activity. No associations were found in the white groups. The positive association between GR activity and cIMT in black men may be the result of a compensatory response to prevent arterial remodelling. The inverse association between GPx activity and blood pressure in black women may indicate a role for decreased GPx activity in hypertension development in this population. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

The O+ contribution and role on the ring current pressure development for CMEs and CIRs using Van Allen Probes observations

NASA Astrophysics Data System (ADS)

Mouikis, C.; Bingham, S.; Kistler, L. M.; Farrugia, C. J.; Spence, H. E.; Gkioulidou, M.

2016-12-01

The ring current responds differently to the different solar and interplanetary storm drivers such as coronal mass injections, (CME's), co-rotating interaction regions (CIR's), high-speed streamers and other structures. The resulting changes in the ring current particle pressure change the global magnetic field, which affects the transport of the radiation belts. In order to determine the field changes during a storm, it is necessary to understand the transport, sources and losses of the particles that contribute to the ring current. The source population of the storm time ring current is the night side plasma sheet. We use Van Allen Probes observations to determine the ring current pressure contribution of the convecting plasma sheet H+ and O+ particles in the storm time development of the ring current. We compare storms that are related to different interplanetary drivers, CMEs and CIRs, as observed at different local times. We find that during the storm main phase most of the ring current pressure in the pre-midnight inner magnetosphere is contributed by particles on open drift paths that cause the development of a strong partial ring current that causes most of the main phase Dst drop. These particles can reach as deep as L 2 and their pressure compares to the local magnetic field pressure as deep as L 3. During the recovery phase, if these particles are not lost at the magnetopause, will become trapped and will contribute to the symmetric ring current. However, the largest difference between the CME and CIR ring current responses during the storm main and early recovery phases is caused by how the 15 - 60 keV O+ responds to these drivers.

Evaluating and improving pressure ulcer care: the VA experience with administrative data.

PubMed

Berlowitz, D R; Halpern, J

1997-08-01

A number of state initiatives are using databases originally developed for nursing home reimbursements to assess the quality of care. Since 1991 the Department of Veterans Affairs (VA; Washington, DC) has been using a long term care administrative database to calculate facility-specific rates of pressure ulcer development. This information is disseminated to all 140 long term care facilities as part of a quality assessment and improvement program. Assessments are performed on all long term care residents on April 1 and October 1, as well as at the time of admission or transfer to a long term care unit. Approximately 18,000 long term care residents are evaluated in each six-month period; the VA rate of pressure ulcer development is approximately 3.5%. Reports of the rates of pressure ulcer development are then disseminated to all facilities, generally within two months of the assessment date. The VA's more than five years' experience in using administrative data to assess outcomes for long term care highlights several important issues that should be considered when using outcome measures based on administrative data. These include the importance of carefully selecting the outcome measure, the need to consider the structure of the database, the role of case-mix adjustment, strategies for reporting rates to small facilities, and methods for information dissemination. Attention to these issues will help ensure that results from administrative databases lead to improvements in the quality of care.

Role of sensory C fibers in hypoxia/ reoxygenation-impaired myogenic constriction of cerebral arteries

PubMed Central

Xie, Hui; Ray, Patricio E.; Short, Billie Lou

2009-01-01

Objective Hypoxia/reoxygenation (H/R) associated with extracorporeal membrane oxygenation disrupts cerebral autoregulation. However, the underlying mechanisms remain poorly understood. The present study was designed to investigate the role of sensory C-fibers in myogenic responsiveness of cerebral arteries. Methods Arterial diameter and intraluminal pressure were simultaneously measured in vitro on rat posterior cerebral arteries. Results Cerebral arteries constricted in response to graded increase in intraluminal pressure (20–100 mmHg, in 20 mmHg increments). In vitro C-fiber desensitization with capsaicin (1 μmol/l, 20 minutes) significantly suppressed myogenic constriction by over 50%, but did not affect 5-hydroxytryptamine (0.01–10 μmol/l) and KCl (120 mmol/l)-induced constriction. Capsazepine (5 μmol/l, 30 minutes), a selective blocker of neuronal vanilloid receptor TRPV1, had similar inhibitory effect on cerebral myogenic constriction to elevated pressure. Cerebral myogenic constriction was significantly attenuated by H/R; the impairment by H/R was further enhanced after C-fiber desensitization (except at a pressure level of 100 mmHg). Discussion These findings indicate that C-fiber activity contributes to myogenic constriction of cerebral arteries under normal and H/R conditions. H/R-impaired myogenic responsiveness is exaggerated by C-fiber dysfunction. These results raise the possibility that therapeutic strategies directed toward preserving C-fiber nerve endings or supplying its constituent neuropeptides could be developed. PMID:19570322

Suppression of LRRC19 promotes cutaneous wound healing in pressure ulcers in mice.

PubMed

Sun, Jie; Wang, Zhijing; Wang, Xirui

2018-02-20

The ischemia-reperfusion (I/R) induced skin lesion has been identified as primary cause of pressure ulcer. Better understanding of the mechanism is required for new therapy development. Leucine rich repeat containing protein 19 (LRRC19) is a recently discovered transmembrane protein containing leucine-rich repeats and plays a role in immune response. To investigate the role of LRRC19 in pressure ulcers, mouse ulcer model was established with two cycles of I/R. The expression of LRRC19 was assessed during injury. siRNA mediated LRRC19 downregulation was applied to investigate the disease severity, immune cell infiltration and pro-inflammatory cytokines production. The primary skin fibroblasts were stimulated with IL-1β to dissect the molecular mechanism. LRRC19 was readily induced in I/R induced lesion site in a pattern mimicking the disease progress as measured by wound area. Knockdown of LRRC19 by siRNA significantly alleviated the disease severity and attenuated immune cell infiltration and pro-inflammatory cytokines production. In primary skin fibroblast model, siRNA knockdown of LRRC19 suppressed IL-1β mediated NFκB activation and its downstream cytokines production. LRRC19 was a novel factor for I/R-induced tissue damage by promoting NFκB dependent pro-inflammatory response. Our results supported that LRRC19 could be a potential therapeutic target for pressure ulcers.

Obstructive Sleep Apnoea/Hypopnoea Syndrome and Hypertension

PubMed Central

Al-Abri, Mohammed A; Al-Hashmi, Khamis M

2008-01-01

The obstructive sleep apnoea/hypopnoea syndrome (OSAHS) is a common disorder, affecting around 2–4% of the middle-aged population. There is a strong association between OSAHS and hypertension, based on animal, large epidemiological and interventional studies. The epidemiological studies have shown a dose-response relationship between apnoea/hypopnoea index (AHI) and the risk of developing hypertension. Different mechanisms may have a role in the process of elevated blood pressure in OSAHS. Sympathetic activity is increased in OSAHS patients during sleep and wakefulness. This increase in sympathetic activity is probably due to activation of baroreflexes and chemoreflexes by frequent arousals and hypoxaemia a result of apnoea or hypopnoea events. Continuous positive airway pressure (CPAP) has been shown to reduce sympathetic stimulation and blood pressure in OSAHS patients. Altered endothelial function may also have a role in the pathogenesis of hypertension in OSAHS subjects. Reduction of nitric oxide (NO) production and increase in the formation of free radicals may be responsible for the impairment of the vasodilatation of micro-vasculature in these subjects as a result of hypoxaemia. It has been shown that effective CPAP therapy has a reversible effect on endothelial dysfunction. PMID:21748071

Cyclic hydrostatic pressure stimulates enhanced bone development in the foetal chick femur in vitro.

PubMed

Henstock, J R; Rotherham, M; Rose, J B; El Haj, A J

2013-04-01

Mechanical loading of bone and cartilage in vivo results in the generation of cyclic hydrostatic forces as bone compression is transduced to fluid pressure in the canalicular network and the joint synovium. It has therefore been suggested that hydrostatic pressure is an important stimulus by which osteochondral cells and their progenitors sense and respond to mechanical loading in vivo. In this study, hydrostatic pressure regimes of 0-279kPa at 0.005-2Hz were applied to organotypically cultured ex vivo chick foetal femurs (e11) for 1hour per day in a custom designed bioreactor for 14days and bone formation assessed by X-ray microtomography and qualified by histology. We found that the mineralised portion of the developing femur cultured under any cyclic hydrostatic pressure regime was significantly larger and/or denser than unstimulated controls but that constant (non-cycling) hydrostatic pressure had no effect on bone growth. Further experiments showed that the increase in bone formation was directly proportional to stimulation frequency (R(2)=0.917), but independent of the magnitude of the pressure applied, whilst even very low frequencies of stimulation (0.005Hz) had significant effects on bone growth. Expression of Type-II collagen in both epiphyses and diaphysis was significantly upregulated (1.48-fold and 1.95-fold respectively), together with osteogenic genes (osteonectin and osteopontin) and the osteocyte maturation marker CD44. This work demonstrates that cyclic hydrostatic pressure promotes bone growth and mineralisation in a developmental model and supports the hypothesis that hydrostatic forces play an important role in regulating bone growth and remodelling in vivo. Copyright © 2013 Elsevier Inc. All rights reserved.

Patient and Practice Perspectives on Strategies for Controlling Blood Pressure, North Carolina, 2010–2012

PubMed Central

Vu, Maihan B.; Halladay, Jacqueline R.; Miller, Cassandra; Garcia, Beverly A.; Cummings, Doyle M.; Cene, Crystal W.; Hinderliter, Alan; Little, Edwin; Rachide, Marjorie; DeWalt, Darren

2014-01-01

Introduction Patient and practice perspectives can inform development of team-based approaches to improving blood pressure control in primary care. We used a community-based participatory research approach to assess patient and practice perceptions regarding the value of team-based strategies for controlling blood pressure in a rural North Carolina population from 2010 through 2012. Methods In-depth interviews were conducted with 41 adults with hypertension, purposely sampled to include diversity of sex, race, literacy, and blood pressure control, and with key office staff at 5 rural primary care practices in the southeastern US “stroke belt.” Interviews explored barriers to controlling blood pressure, the practice’s role in controlling blood pressure, and opinions on the use of team care delivery. Results Patients reported that provider strategies to optimize blood pressure control should include regular visits, medication adjustment, side-effect discussion, and behavioral counseling. When discussing team-based approaches to hypertension care, patients valued verbal encouragement, calls from the doctor’s office, and the opportunity to ask questions. However, they voiced concerns about the effect of having too many people involved in their care. Practice staff focused on multiple, broad methods to control blood pressure including counseling, regular office visits, media to improve awareness, and support groups. An explicit focus of delivering care as teams was a newer concept. Conclusion When developing a team approach to hypertension treatment, patients value high-quality communication and not losing their primary relationship with their provider. Practice staff members were open to a team-based approach but had limited knowledge of what such an approach would entail. PMID:24762533

Occupational role stress is associated with higher cortisol reactivity to acute stress.

PubMed

Wirtz, Petra H; Ehlert, Ulrike; Kottwitz, Maria U; La Marca, Roberto; Semmer, Norbert K

2013-04-01

We investigated whether occupational role stress is associated with differential levels of the stress hormone cortisol in response to acute psychosocial stress. Forty-three medication-free nonsmoking men aged between 22 and 65 years (mean ± SEM: 44.5 ± 2) underwent an acute standardized psychosocial stress task combining public speaking and mental arithmetic in front of an audience. We assessed occupational role stress in terms of role conflict and role ambiguity (combined into a measure of role uncertainty) as well as further work characteristics and psychological control variables including time pressure, overcommitment, perfectionism, and stress appraisal. Moreover, we repeatedly measured salivary cortisol and blood pressure levels before and after stress exposure, and several times up to 60 min thereafter. Higher role uncertainty was associated with a more pronounced cortisol stress reactivity (p = .016), even when controlling for the full set of potential confounders (p < .001). Blood pressure stress reactivity was not associated with role uncertainty. Our findings suggest that occupational role stress in terms of role uncertainty acts as a background stressor that is associated with increased HPA-axis reactivity to acute stress. This finding may represent a potential mechanism regarding how occupational role stress may precipitate adverse health outcomes.

The role of lung inflation and sodium transport in airway liquid clearance during lung aeration in newborn rabbits.

PubMed

Siew, Melissa L; Wallace, Megan J; Allison, Beth J; Kitchen, Marcus J; te Pas, Arjan B; Islam, M Sirajul; Lewis, Robert A; Fouras, Andreas; Yagi, Naoto; Uesugi, Kentaro; Hooper, Stuart B

2013-04-01

Recent phase-contrast X-ray imaging studies suggest that inspiration primarily drives lung aeration and airway liquid clearance at birth, which questions the role of adrenaline-induced activation of epithelial sodium channels (ENaCs). We hypothesized that pressures generated by inspiration have a greater role in airway liquid clearance than do ENaCs after birth. Rabbit pups (30 d of gestation) were delivered and sedated, and 0.1 ml of saline (S) or amiloride (Am; an ENaC inhibitor) was instilled into the lungs before mechanical ventilation. Two other groups (30 d of gestation) were treated similarly but were also given adrenaline (S/Ad and Am/Ad) before mechanical ventilation. Amiloride and adrenaline did not affect functional residual capacity (FRC) recruitment (P > 0.05). Amiloride increased the rate of FRC loss between inflations (Am: -5.2 ± 0.6 ml/kg/s), whereas adrenaline reduced the rate of FRC loss (S/Ad: -1.9 ± 0.3 ml/kg/s) as compared with saline-treated controls (S: -3.5 ± -0.6 ml/kg/s; P < 0.05). These data indicate that inspiration is a major determinant of airway liquid clearance and FRC development during positive pressure ventilation. Although ENaC inhibition and adrenaline administration had no detectable effect on FRC development, ENaC may help to prevent liquid from re-entering the airways during expiration.

The role of H-bond in the high-pressure chemistry of model molecules

NASA Astrophysics Data System (ADS)

Fanetti, Samuele; Citroni, Margherita; Dziubek, Kamil; Medre Nobrega, Marcelo; Bini, Roberto

2018-03-01

Pressure is an extraordinary tool to modify direction and strength of intermolecular interactions with important consequences on the chemical stability of molecular materials. The decrease of the distance among nearest neighbour molecules can give rise to reactive configurations reflecting the crystal arrangement and leading to association processes. In this context, the role of the H-bonds is very peculiar because their usual strengthening with rising pressure does not necessarily configure a decrease of the reaction activation energy but, on the contrary, can give rise to an anomalous stability of the system. In spite of this central role, the mechanisms by which a chemical reaction is favoured or prevented by H-bonding under high pressure conditions is a poorly explored field. Here we review a few studies where the chemical behaviour of simple molecular systems under static compression was related to the H-bonding evolution with pressure. These results are able to clarify a wealth of changes of the chemical and physical properties caused by the strengthening with pressure of the H-bonding network and provide additional tools to understand the mechanisms of high-pressure reactivity, a mandatory step to make these synthetic methods of potential interest for applicative purposes.

Deletion of Interleukin-6 Attenuates Pressure Overload-Induced Left Ventricular Hypertrophy and Dysfunction

PubMed Central

Afzal, Muhammad R.; Samanta, Anweshan; Xuan, Yu-Ting; Girgis, Magdy; Elias, Harold K; Zhu, Yanqing; Davani, Arash; Yang, Yanjuan; Chen, Xing; Ye, Sheng; Wang, Ou-Li; Chen, Lei; Hauptman, Jeryl; Vincent, Robert J.; Dawn, Buddhadeb

2016-01-01

Rationale The role of interleukin (IL)-6 in the pathogenesis of cardiac myocyte hypertrophy remains controversial. Objective To conclusively determine whether IL-6 signaling is essential for the development of pressure overload-induced left ventricular (LV) hypertrophy, and to elucidate the underlying molecular pathways. Methods and Results Wild-type (WT) and IL-6 knockout (IL-6−/−) mice underwent sham surgery or transverse aortic constriction (TAC) to induce pressure overload. Serial echocardiograms and terminal hemodynamic studies revealed attenuated LV hypertrophy and superior preservation of LV function in IL-6−/− mice after TAC. The extents of LV remodeling, fibrosis, and apoptosis were reduced in IL-6−/− hearts after TAC. Transcriptional and protein assays of myocardial tissue identified CaMKII and STAT3 activation as important underlying mechanisms during cardiac hypertrophy induced by TAC. The involvement of these pathways in myocyte hypertrophy was verified in isolated cardiac myocytes from WT and IL-6−/− mice exposed to pro-hypertrophy agents. Furthermore, overexpression of CaMKII in H9c2 cells increased STAT3 phosphorylation, and exposure of H9c2 cells to IL-6 resulted in STAT3 activation that was attenuated by CaMKII inhibition. Together these results identify the importance of CaMKII-dependent activation of STAT3 during cardiac myocyte hypertrophy via IL-6 signaling. Conclusions Genetic deletion of IL-6 attenuates TAC-induced LV hypertrophy and dysfunction, indicating a critical role played by IL-6 in the pathogenesis of LV hypertrophy in response to pressure overload. CaMKII plays an important role in IL-6-induced STAT3 activation and consequent cardiac myocyte hypertrophy. These findings may have significant therapeutic implications for LV hypertrophy and failure in patients with hypertension. PMID:27126808

Role of load history in intervertebral disc mechanics and intradiscal pressure generation.

PubMed

Hwang, David; Gabai, Adam S; Yu, Miao; Yew, Alvin G; Hsieh, Adam H

2012-01-01

Solid-fluid interactions play an important role in mediating viscoelastic behaviour of biological tissues. In the intervertebral disc, water content is governed by a number of factors, including age, disease and mechanical loads, leading to changes in stiffness characteristics. We hypothesized that zonal stress distributions depend on load history, or the prior stresses experienced by the disc. To investigate these effects, rat caudal motion segments were subjected to compressive creep biomechanical testing in vitro using a protocol that consisted of two phases: a Prestress Phase (varied to represent different histories of load) followed immediately by an Exertion Phase, identical across all Prestress groups. Three analytical models were used to fit the experimental data in order to evaluate load history effects on gross and zonal disc mechanics. Model results indicated that while gross transient response was insensitive to load history, there may be changes in the internal mechanics of the disc. In particular, a fluid transport model suggested that the role of the nucleus pulposus in resisting creep during Exertion depended on Prestress conditions. Separate experiments using similarly defined load history regimens were performed to verify these predictions by measuring intradiscal pressure with a fibre optic sensor. We found that the ability for intradiscal pressure generation was load history-dependent and exhibited even greater sensitivity than predicted by analytical models. A 0.5 MPa Exertion load resulted in 537.2 kPa IDP for low magnitude Prestress compared with 373.7 kPa for high magnitude Prestress. Based on these measurements, we developed a simple model that may describe the pressure-shear environment in the nucleus pulposus. These findings may have important implications on our understanding of how mechanical stress contributes to disc health and disease etiology.

Involvement of nitric oxide in the wound bed microcirculatory change during negative pressure wound therapy.

PubMed

Sano, Hitomi; Ichioka, Shigeru

2015-08-01

This study investigated the role of nitric oxide (NO) in the mechanism of blood flow increase in the wound bed during negative pressure wound therapy (NPWT). We developed an improved experimental model that allowed visualisation of the wound bed microcirculation under NPWT. Wounds were created on the mouse ear, taking care to preserve the subdermal vascular plexus, because the wound bed microcirculation was visualised using an intravital microscope system. We investigated whether application of a NO synthase inhibitor (N(G) -nitro-l-arginine methyl ester: L-NAME) might diminish the effect of the NPWT in increasing the wound blood flow. The experimental animals were divided into a negative pressure group (negative pressure of -125 mmHg applied to the wound for 5 minutes; n = 8), and a negative pressure plus L-NAME group (administration of L-NAME prior to application of the negative pressure; n = 8). In the negative pressure group, significant increase of blood flow was observed at 1 minute after the negative pressure application, which was sustained until 5 minutes. On the contrary, in the negative pressure plus L-NAME group, no significant changes were observed throughout the period of observation. These findings suggest that NO synthesis is involved in the wound bed microcirculatory change induced by NPWT. © 2013 The Authors. International Wound Journal © 2013 Medicalhelplines.com Inc and John Wiley & Sons Ltd.

The expanding role of aerosols in systemic drug delivery, gene therapy, and vaccination.

PubMed

Laube, Beth L

2005-09-01

Aerosolized medications have been used for centuries to treat respiratory diseases. Until recently, inhalation therapy focused primarily on the treatment of asthma and chronic obstructive pulmonary disease, and the pressurized metered-dose inhaler was the delivery device of choice. However, the role of aerosol therapy is clearly expanding beyond that initial focus. This expansion has been driven by the Montreal protocol and the need to eliminate chlorofluorocarbons (CFCs) from traditional metered-dose inhalers, by the need for delivery devices and formulations that can efficiently and reproducibly target the systemic circulation for the delivery of proteins and peptides, and by developments in medicine that have made it possible to consider curing lung diseases with aerosolized gene therapy and preventing epidemics of influenza and measles with aerosolized vaccines. Each of these drivers has contributed to a decade or more of unprecedented research and innovation that has altered how we think about aerosol delivery and has expanded the role of aerosol therapy into the fields of systemic drug delivery, gene therapy, and vaccination. During this decade of innovation, we have witnessed the coming of age of dry powder inhalers, the development of new soft mist inhalers, and improved pressurized metered-dose inhaler delivery as a result of the replacement of CFC propellants with hydrofluoroalkane. The continued expansion of the role of aerosol therapy will probably depend on demonstration of the safety of this route of administration for drugs that have their targets outside the lung and are administered long term (eg, insulin aerosol), on the development of new drugs and drug carriers that can efficiently target hard-to-reach cell populations within the lungs of patients with disease (eg, patients with cystic fibrosis or lung cancer), and on the development of devices that improve aerosol delivery to infants, so that early intervention in disease processes with aerosol therapy has a high probability of success.

Role of the autonomic nervous system in the control of heart rate and blood pressure in the defence reaction in conscious dogs.

PubMed

Federici, A; Rizzo, A; Cevese, A

1985-04-01

The present study was performed on conscious, chronically instrumented dogs, which underwent selective blockade of sympathetic adrenergic and vagal outflows. Excitements were performed on these animals in normal states (N), after chronic treatment with guanethidine, for sympathetic blockade (SB), after cold vagal blockade (VB), and after combined sympathetic and vagal blockade (SB + VB). Heart rate and arterial blood pressure were monitored in all the experiments, while a group of dogs was also tested with an electromagnetic flowmeter on the superior mesenteric artery. The role of the sympathetic and parasympathetic controls in the defence reaction was assumed from comparison of experiments performed in the presence or in the absence of each (or both) autonomic component(s). In the SB + VB condition, excitement was followed by sudden hypotension, without changes in heart rate. In VB experiments, a brief and transient hypotension appeared, followed by gradually developed hypertension, while heart rate progressively rose in about 5 s; there was no sudden increase in mesenteric vascular resistance, which contrasted with the very marked reaction in N experiments. Under vagal control alone (SB), the stimulus elicited prompt tachycardia and hypertension, followed by a period of moderately reduced blood pressure. We conclude that, while the defence reaction leads to a sudden fall of arterial blood pressure, in the absence of compensatory mechanisms, both branches of the autonomic nervous system play a protective role against hypotension. In addition, the modulation of the vagal outflow, leading to sudden changes in the heart performance, seems to be responsible for the initiation of the overall haemodynamic adjustments following excitements. The possibility that withdrawal of the parasympathetic outflow to the heart may raise arterial blood pressure was verified in a special experiment in which artificial vagal stimulation in a conscious (vagal blocked) dog, was turned off for brief periods, before and after guanethidine. This led to changes in blood pressure and heart rate very similar to those seen at the onset of the defence reaction, both in N and SB conditions.

Population-wide sodium reduction: The bumpy road from evidence to policy

PubMed Central

Appel, Lawrence J; Angell, Sonia Y; Cobb, Laura K; Limper, Heather; Nelson, David E.; Samet, Jonathan M; Brownson, Ross C.

2016-01-01

Elevated blood pressure is a highly prevalent condition that is etiologically related to coronary heart disease and stroke, two of the leading causes of morbidity and mortality throughout the world. Excess salta (sodium chloride) intake is a major determinant of elevated blood pressure. In this paper we discuss the scientific rationale for population-wide salt reduction, the types and strength of available evidence, policy-making on dietary salt in the United States and other countries, and the role and impact of key stakeholders. We highlight a number of lessons learned, many of which are germane to policy development in other domains. PMID:22626000

Socio spatial adaptation as a resilience form of native unplanned settlement in confrontation with new planned settlement development pressure (case study: enclave native settlement in Serpong, Tangerang)

NASA Astrophysics Data System (ADS)

Ischak, Mohammad; Setioko, Bambang; Nurgandarum, Dedes

2017-12-01

Urban growth refers to expansion of a metropolitan into sub urban areas as the surrounding environment, with no exception of Jakarta city due to limited availability and high price of land within the city. The city of Jakarta, as a metropolitan, carries of expansion in its surrounding environment including Tangerang. Privat developers may an important role in this urban growth through their large scale of new settlement development project. The formation of establishment of enclave native unplanned sub urban settlement scattered within planned new settlement in Tangerang is to be an consequence of Jakarta urban growth. This fenomena could be comprehended as a form of resilience native settlement in confrontation with the new planned settlement pressure. The aim of this research, presented in this paper is to understand the socio-spatial concept of those enclave native settlement as an adaptation form to the new planned settlement pressure. Through descriptive qualitative research method, with indepth interview as a main research instrument, this research could depict or uncover the facts that there are various form of socio-spatial adaptation as the main theme of resilience native suburban settlement formation.

Numerical analysis of pressure and porosity evolution in lava domes during periodic degassing conditions

NASA Astrophysics Data System (ADS)

Hyman, D.; Bursik, M. I.; Pitman, E. B.

2017-12-01

The collapse or explosive breakup of growing and degassing lava domes presents a significant hazard due to the generation of dense, mobile pyroclastic flows as well as the wide dispersal of dense ballistic blocks. Lava dome stability is in large part governed by the balance of transport and storage of gas within the pore space. Because pore pressurization reduces the effective stress within a dome, the transient distribution of elevated gas pressure is critically important to understanding dome break up. We combine mathematical and numerical analyses to gain a better understanding of the temporal variation in gas flow and storage within the dome system. In doing so, we develop and analyze new governing equations describing nonlinear gas pressure diffusion in a deforming dome with an evolving porosity field. By relating porosity, permeability, and pressure, we show that the flux of gas through a dome is highly sensitive to the porosity distribution and viscosity of the lava, as well as the timescale and magnitude of the gas supply. The numerical results suggest that the diffusion of pressure and porosity variations play an integral role in the cyclic growth and destruction of small domes.The nearly continuous cycles of lava dome growth, pressurization, and failure that have characterized the last two decades of eruptive history at Volcán Popocatépetl, Mexico provide excellent natural data with which to compare new models of transient dome pressurization. At Popocatépetl, periodic pressure increases brought on by changes in gas supply into the base of the dome may play a role in its cyclic growth and destruction behavior. We compare our model of cyclic pressurization with lava dome survival data from Popocatépetl. We show that transient changes in pore pressure explain how small lava domes evolve to a state of criticality before explosion or collapse. Additionally, numerical analyses presented here suggest that short-term oscillations cannot arise within the dome, and must be the result of an oscillating supply of gas into the dome. The oscillating gas supply may result from alternating gas-rich and gas-poor regions of rising magma, so-called "porosity waves" within the conduit. These internal pressure fluctuations lead to periodic reductions in the stress required to fracture the dome and induce explosion.

MESOSCALE MODELING OF DEFLAGRATION-INDUCED DECONSOLIDATION IN POLYMER-BONDED EXPLOSIVES

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

Springer, H K; Glascoe, E A; Reaugh, J E

Initially undamaged polymer-bonded explosives can transition from conductive burning to more violent convective burning via rapid deconsolidation at higher pressures. The pressure-dependent infiltration of cracks and pores, i.e., damage, by product gases at the burn-front is a key step in the transition to convective burning. However, the relative influence of pre-existing damage and the evolution of deflagration-induced damage during the transition to convective burning is not well understood. The objective of this study is to investigate the role of microstructure and initial pressurization on deconsolidation. We performed simulations using the multi-physics hydrocode, ALE3D. HMX-Viton A served as our model explosive.more » A Prout-Tompkins chemical kinetic model, Vielle's Law pressure-dependent burning, Gruneisen equation-of-state, and simplified strength model were used for the HMX. The propensity for deconsolidation increased with increasing defect size and decreasing initial pressurization, as measured by the increase in burning surface area. These studies are important because they enable the development of continuum-scale damage models and the design of inherently safer explosives.« less

Microelectromechanical system pressure sensor integrated onto optical fiber by anodic bonding.

PubMed

Saran, Anish; Abeysinghe, Don C; Boyd, Joseph T

2006-03-10

Optical microelectromechanical system pressure sensors based on the principle of Fabry-Perot interferometry have been developed and fabricated using the technique of silicon-to-silicon anodic bonding. The pressure sensor is then integrated onto an optical fiber by a novel technique of anodic bonding without use of any adhesives. In this anodic bonding technique we use ultrathin silicon of thickness 10 microm to bond the optical fiber to the sensor head. The ultrathin silicon plays the role of a stress-reducing layer, which helps the bonding of an optical fiber to silicon having conventional wafer thickness. The pressure-sensing membrane is formed by 8 microm thick ultrathin silicon acting as a membrane, thus eliminating the need for bulk silicon etching. The pressure sensor integrated onto an optical fiber is tested for static response, and experimental results indicate degradation in the fringe visibility of the Fabry-Perot interferometer. This effect was mainly due to divergent light rays from the fiber degrading the fringe visibility. This effect is demonstrated in brief by an analytical model.

Patient participation in pressure injury prevention: giving patient's a voice.

PubMed

Latimer, Sharon; Chaboyer, Wendy; Gillespie, Brigid

2014-12-01

Pressure injuries burden patients and healthcare organisations, with some preventative practices having little impact on prevalence reduction. Patient participation in care may be an effective pressure injury prevention strategy, yet patient preferences are unknown. The aim of this interpretive study was to describe patients' perceptions of their current and future role in pressure injury prevention. Semi-structured interviews were conducted with 20 adult inpatients recruited from four medical units, at two Australian metropolitan hospitals. Interview data were analysed using content analysis, with three categories emerging: 'experiencing pressure injuries'; 'participating in pressure injury prevention'; and 'resourcing pressure injury prevention and treatment'. These categories reflect the complex nature of participants' pressure injury experience. The findings suggest participants gather pressure injury knowledge from first-hand and vicarious experience; knowledge they bring to hospital. Most participants preferred a proactive pressure injury prevention role. Many identified barriers in the healthcare environment that impeded their participation and affected their experience of pressure injuries and pressure injury prevention. If patient participation as a pressure injury prevention strategy is to be considered, nurses and organisations need to view patients as partners. © 2013 Nordic College of Caring Science.

Attenuated hypertrophic response to pressure overload in a lamin A/C haploinsufficiency mouse.

PubMed

Cupesi, Mihaela; Yoshioka, Jun; Gannon, Joseph; Kudinova, Anastacia; Stewart, Colin L; Lammerding, Jan

2010-06-01

Inherited mutations cause approximately 30% of all dilated cardiomyopathy cases, with autosomal dominant mutations in the LMNA gene accounting for more than one third of these. The LMNA gene encodes the nuclear envelope proteins lamins A and C, which provide structural support to the nucleus and also play critical roles in transcriptional regulation. Functional deletion of a single allele is sufficient to trigger dilated cardiomyopathy in humans and mice. However, whereas Lmna(-/-) mice develop severe muscular dystrophy and dilated cardiomyopathy and die by 8 weeks of age, heterozygous Lmna(+/-) mice have a much milder phenotype, with changes in ventricular function and morphology only becoming apparent at 1 year of age. Here, we studied 8- to 20-week-old Lmna(+/-) mice and wild-type littermates in a pressure overload model to examine whether increased mechanical load can accelerate or exacerbate myocardial dysfunction in the heterozygotes. While overall survival was similar between genotypes, Lmna(+/-) animals had a significantly attenuated hypertrophic response to pressure overload as evidenced by reduced ventricular mass and myocyte size. Analysis of pressure overload-induced transcriptional changes suggested that the reduced hypertrophy in the Lmna(+/-) mice was accompanied by impaired activation of the mechanosensitive gene Egr-1. In conclusion, our findings provide further support for a critical role of lamins A and C in regulating the cellular response to mechanical stress in cardiomyocytes and demonstrate that haploinsufficiency of lamins A and C alone is sufficient to alter hypertrophic responses and cardiac function in the face of pressure overload in the heart. (c) 2009 Elsevier Ltd. All rights reserved.

Attenuated hypertrophic response to pressure overload in a lamin A/C haploinsufficiency mouse

PubMed Central

Cupesi, Mihaela; Yoshioka, Jun; Gannon, Joseph; Kudinova, Anastacia; Stewart, Colin L.; Lammerding, Jan

2009-01-01

Inherited mutations cause approximately 30% of all dilated cardiomyopathy cases, with autosomal dominant mutations in the LMNA gene accounting for more than one third of these. The LMNA gene encodes the nuclear envelope proteins lamins A and C, which provide structural support to the nucleus and also play critical roles in transcriptional regulation. Functional deletion of a single allele is sufficient to trigger dilated cardiomyopathy in humans and mice. However, whereas Lmna−/− mice develop severe muscular dystrophy and dilated cardiomyopathy and die by 8 weeks of age, heterozygous Lmna+/− mice have a much milder phenotype, with changes in ventricular function and morphology only becoming apparent at one year of age. Here, we studied 8 to 20 week old Lmna+/− mice and wild-type littermates in a pressure overload model to examine whether increased mechanical load can accelerate or exacerbate myocardial dysfunction in the heterozygotes. While overall survival was similar between genotypes, Lmna+/− animals had a significantly attenuated hypertrophic response to pressure overload as evidenced by reduced ventricular mass and myocyte size. Analysis of pressure-overload induced transcriptional changes suggested that the reduced hypertrophy in the Lmna+/− mice was accompanied by impaired activation of the mechanosensitive gene Egr-1. In conclusion, our findings provide further support for a critical role of lamins A and C in regulating the cellular response to mechanical stress in cardiomyocytes and demonstrate that haploinsufficiency of lamins A and C alone is sufficient to alter hypertrophic responses and cardiac function in the face of pressure overload in the heart. PMID:19913544

Role of central command in carotid baroreflex resetting in humans during static exercise

NASA Technical Reports Server (NTRS)

Ogoh, S.; Wasmund, W. L.; Keller, D. M.; O-Yurvati, A.; Gallagher, K. M.; Mitchell, J. H.; Raven, P. B.

2002-01-01

The purpose of the experiments was to examine the role of central command in the exercise-induced resetting of the carotid baroreflex. Eight subjects performed 30 % maximal voluntary contraction (MVC) static knee extension and flexion with manipulation of central command (CC) by patellar tendon vibration (PTV). The same subjects also performed static knee extension and flexion exercise without PTV at a force development that elicited the same ratings of perceived exertion (RPE) as those observed during exercise with PTV in order to assess involvement of the exercise pressor reflex. Carotid baroreflex (CBR) function curves were modelled from the heart rate (HR) and mean arterial pressure (MAP) responses to rapid changes in neck pressure and suction during steady state static exercise. Knee extension exercise with PTV (decreased CC activation) reset the CBR-HR and CBR-MAP to a lower operating pressure (P < 0.05) and knee flexion exercise with PTV (increased CC activation) reset the CBR-HR and CBR-MAP to a higher operating pressure (P < 0.05). Comparison between knee extension and flexion exercise at the same RPE with and without PTV found no difference in the resetting of the CBR-HR function curves (P > 0.05) suggesting the response was determined primarily by CC activation. However, the CBR-MAP function curves were reset to operating pressures determined by both exercise pressor reflex (EPR) and central command activation. Thus the physiological response to exercise requires CC activation to reset the carotid-cardiac reflex but requires either CC or EPR to reset the carotid-vasomotor reflex.

Gender, family structure and cardiovascular activity during the working day and evening.

PubMed

Steptoe, A; Lundwall, K; Cropley, M

2000-02-01

This study applied psychophysiological methods to the investigation of social roles and well-being, using cardiovascular function over a working day and evening as an index of physiological activation. One hundred and sixty-two full-time school teachers (102 women and 60 men) were assessed using automated ambulatory blood pressure monitoring apparatus, with readings every 20 min through the working day (9.00 am-5.40 pm), and every 30 min in the evening (6.00-10.30 pm). The influence of gender, marital status and parenthood (defined as having at least one child living at home) on blood pressure during the working day and on day-evening differences was examined. There were no differences in blood pressure and heart rate across the working day in relation to marital roles or family structure. However, the decrease in blood pressure between working day and evening was greatest in parents, intermediate in married non-parents, and smallest in single participants without children. Differences in systolic pressure adjusted for age and body mass index averaged -4.46, -1.76 and +0.22 mmHg in the three groups, respectively. A similar pattern was observed for diastolic pressure but not heart rate. We also found that the day-evening fall in systolic pressure was moderated by social support, with the greatest change (mean adjusted difference -6.76 mmHg) in parents who reported high levels of social support. These blood pressure responses did not differ between men and women, and there was no indication of multiple role strain for full-time working mothers. The results were independent of concomitant physical activity, location during measurement, or reported job strain. We argue that findings are consistent with an enhancement model of multiple social roles, and with lower allostatic load on individuals who are working, married and parents. Psychophysiological studies of daily life can complement epidemiological and sociological investigations of social roles and health.

Genomic data as the 'hitchhiker's guide' to cattle adaptation: time to track the milestones of past selection in the bovine genome

USDA-ARS?s Scientific Manuscript database

The bovine species have witnessed and played a major role in the drastic socio-economical changes that shaped our culture over the last 10,000 years. During this journey, cattle “hitchhiked” on human development and colonized the world, facing strong selective pressures such as dramatic environmenta...

Applicability of implantable telemetry systems in cardiovascular research.

NASA Technical Reports Server (NTRS)

Krutz, R. W.; Rader, R. D.; Meehan, J. P.; Henry, J. P.

1971-01-01

This paper briefly describes the results of an experimental program undertaken to develop and apply implanted telemetry to cardiovascular research. Because of the role the kidney may play in essential hypertension, emphasis is placed on telemetry's applicability in the study of renal physiology. Consequently, the relationship between pressure, flow, and hydraulic impedance are stressed. Results of an exercise study are given.

Role of construction debris in release of copper, chromium, and arsenic from treated wood structures

Treesearch

Stan T. Lebow; Steven A. Halverson; Jeffrey J. Morrell; John Simonsen

Recent research on the release of wood preservatives from treated wood used in sensitive environments has not considered the potential contribution from construction residues. This study sought to develop leaching rate data for small construction debris and compare those to the release rate from treated wood itself. Western hemlock boards were pressure treated with...

Teaching Renewal for Midcareer Faculty: Attending to the Whole Person

ERIC Educational Resources Information Center

Ross, Catherine

2015-01-01

In light of the research on the distinct needs of midcareer faculty and the pressures faced by this group in the academy, we offer here an example of an educational development effort that looks at the renewal of teaching through the lens of renewing the whole person in his/her academic roles. Opportunities for midcareer faculty to focus on…

The Role of Glaciation in Slope Instability of Arctic Trough Mouth Fans: An Example of the NW Barents Sea

NASA Astrophysics Data System (ADS)

Urgeles, R.; Llopart, J.; Lucchi, R.; Rebesco, M.; Brückner, N. W.; Rüther, D. C.; Lantzsch, H.

2017-12-01

Submarine slope instability plays a major role in the development of Arctic Trough Mouth Fans (TMFs). TMFs consist of an alternation of rapidly deposited glacigenic debris flows and a sequence of well-layered plumites and hemipelagic sediments. In this sedimentary context, shallow geophysical data and core samples indicate that there is a specific timing (i.e. shortly after the deglaciation phase) for the occurrence of slope failures. High mean sedimentation rates during glacial maxima of up to 18 kg m-2 yr-1 likely allow excess pore pressure to develop in the water rich plumites and hemipelagic sediments deposited in the previous deglacial period, particularly where such plumites attain a significant thickness. Basin numerical models considering the effect of (1) sediment physical properties, (2) polar margin architecture and (3) ice stream sediment dispersal patterns on resulting stresses, fluid flow and slope failure initiation of the Storfjorden Trough Mouth Fan, NW Barents Sea, show that during glacial maxima, ice streams and rapid accumulation of glacigenic debris flows on the slope induce pore pressure build-up in continental shelf/upper slope sediments. The overpressure developed during glacial maxima remains during the deglacial phase. This overpressure combined with downslope stratification of high water content and low shear strength deglacial/interglacial sediments results in a significant decrease in the factor of safety of the upper slope sediments. The position of the submarine landslides in the stratigraphic record suggest, however, that such excess pore pressure is not enough to trigger the slope failures and indicate that earthquakes related to isostatic rebound are likely involved in the final activation.

Drp1-Dependent Mitochondrial Autophagy Plays a Protective Role Against Pressure Overload-Induced Mitochondrial Dysfunction and Heart Failure.

PubMed

Shirakabe, Akihiro; Zhai, Peiyong; Ikeda, Yoshiyuki; Saito, Toshiro; Maejima, Yasuhiro; Hsu, Chiao-Po; Nomura, Masatoshi; Egashira, Kensuke; Levine, Beth; Sadoshima, Junichi

2016-03-29

Mitochondrial autophagy is an important mediator of mitochondrial quality control in cardiomyocytes. The occurrence of mitochondrial autophagy and its significance during cardiac hypertrophy are not well understood. Mice were subjected to transverse aortic constriction (TAC) and observed at multiple time points up to 30 days. Cardiac hypertrophy developed after 5 days, the ejection fraction was reduced after 14 days, and heart failure was observed 30 days after TAC. General autophagy was upregulated between 1 and 12 hours after TAC but was downregulated below physiological levels 5 days after TAC. Mitochondrial autophagy, evaluated by electron microscopy, mitochondrial content, and Keima with mitochondrial localization signal, was transiently activated at ≈3 to 7 days post-TAC, coinciding with mitochondrial translocation of Drp1. However, it was downregulated thereafter, followed by mitochondrial dysfunction. Haploinsufficiency of Drp1 abolished mitochondrial autophagy and exacerbated the development of both mitochondrial dysfunction and heart failure after TAC. Injection of Tat-Beclin 1, a potent inducer of autophagy, but not control peptide, on day 7 after TAC, partially rescued mitochondrial autophagy and attenuated mitochondrial dysfunction and heart failure induced by overload. Haploinsufficiency of either drp1 or beclin 1 prevented the rescue by Tat-Beclin 1, suggesting that its effect is mediated in part through autophagy, including mitochondrial autophagy. Mitochondrial autophagy is transiently activated and then downregulated in the mouse heart in response to pressure overload. Downregulation of mitochondrial autophagy plays an important role in mediating the development of mitochondrial dysfunction and heart failure, whereas restoration of mitochondrial autophagy attenuates dysfunction in the heart during pressure overload. © 2016 American Heart Association, Inc.

Language at Three Timescales: The Role of Real-Time Processes in Language Development and Evolution.

PubMed

McMurray, Bob

2016-04-01

Evolutionary developmental systems (evo-devo) theory stresses that selection pressures operate on entire developmental systems rather than just genes. This study extends this approach to language evolution, arguing that selection pressure may operate on two quasi-independent timescales. First, children clearly must acquire language successfully (as acknowledged in traditional evo-devo accounts) and evolution must equip them with the tools to do so. Second, while this is developing, they must also communicate with others in the moment using partially developed knowledge. These pressures may require different solutions, and their combination may underlie the evolution of complex mechanisms for language development and processing. I present two case studies to illustrate how the demands of both real-time communication and language acquisition may be subtly different (and interact). The first case study examines infant-directed speech (IDS). A recent view is that IDS underwent cultural to statistical learning mechanisms that infants use to acquire the speech categories of their language. However, recent data suggest is it may not have evolved to enhance development, but rather to serve a more real-time communicative function. The second case study examines the argument for seemingly specialized mechanisms for learning word meanings (e.g., fast-mapping). Both behavioral and computational work suggest that learning may be much slower and served by general-purpose mechanisms like associative learning. Fast-mapping, then, may be a real-time process meant to serve immediate communication, not learning, by augmenting incomplete vocabulary knowledge with constraints from the current context. Together, these studies suggest that evolutionary accounts consider selection pressure arising from both real-time communicative demands and from the need for accurate language development. Copyright © 2016 Cognitive Science Society, Inc.

Roles of air stored in burrows of the mudskipper Boleophthalmus pectinirostris for adult respiration and embryonic development.

PubMed

Toba, A; Ishimatsu, A

2014-03-01

Air was stored in 90% of Boleophthalmus pectinirostris burrows in summer breeding months when fish were active on the mudflat surface during low tide but only in 50% of burrows in overwintering months when the fish confined themselves to burrows. The volume of gas recovered from the burrows ranged from 30 to > 400 ml. The partial pressure of oxygen (PO₂) of the gas varied from 5 to 20 kPa and was inversely related to the partial pressure of carbon dioxide (PCO₂) in all but the wintering periods. Sampling in July demonstrated that gas was stored in both male and female burrows with no difference in volume, PO₂ or PCO₂ between them. Adult fish were able to survive total submersion in hypoxic (PO₂ = 1.96 kPa) water for 8 h, but no embryos survived to hatch in the hypoxic aquatic environment. Thus, the deposited air appears to be a crucial source of oxygen for the embryos developing in the egg chamber of the burrow, but may play only a subsidiary role for adult respiration during presumed high-tide confinement. © 2014 The Fisheries Society of the British Isles.

Short review of high-pressure crystal growth and magnetic and electrical properties of solid-state osmium oxides

NASA Astrophysics Data System (ADS)

Yamaura, Kazunari

2016-04-01

High-pressure crystal growth and synthesis of selected solid-state osmium oxides, many of which are perovskite-related types, are briefly reviewed, and their magnetic and electrical properties are introduced. Crystals of the osmium oxides, including NaOsO3, LiOsO3, and Na2OsO4, were successfully grown under high-pressure and high-temperature conditions at 6 GPa in the presence of an appropriate amount of flux in a belt-type apparatus. The unexpected discovery of a magnetic metal-insulator transition in NaOsO3, a ferroelectric-like transition in LiOsO3, and high-temperature ferrimagnetism driven by a local structural distortion in Ca2FeOsO6 may represent unique features of the osmium oxides. The high-pressure and high-temperature synthesis and crystal growth has played a central role in the development of solid-state osmium oxides and the elucidation of their magnetic and electronic properties toward possible use in multifunctional devices.

Are Medications Involved in Vision and intracranial Pressure Changes Seen in Spaceflight?

NASA Technical Reports Server (NTRS)

Wotring, V. E.

2016-01-01

Some crewmembers have experienced changes in their vision after long-duration spaceflight on the ISS. These impairments include visual performance decrements, development of cotton-wool spots or choroidal folds, optic-disc edema, optic nerve sheath distention, and/or posterior globe flattening with varying degrees of severity and permanence. These changes are now used to define the visual impairment/intracranial pressure (VIIP) syndrome. The reasons for these potentially debilitating medical issues are currently unknown. The potential role of administered medications has not yet been examined, but it is known that many medications can have side effects that are similar to VIIP symptoms. Some medications raise blood pressure, which can affect intracranial pressure. Many medications that act in the central nervous system can affect intracranial pressures and/or vision. About 40% of the medications in the ISS kit are known to cause side effects involving changes in blood pressure, intracranial pressure and/or vision. For this reason, we proposed an investigation of the potential relationship between ISS medications and their risk of causing or exacerbating VIIP-like symptoms. The purpose of this study was to use medication usage records for affected and unaffected crew to determine if use of particular medications seemed to correlate with VIIP occurrence or severity.

Super-atmospheric pressure ionization mass spectrometry and its application to ultrafast online protein digestion analysis.

PubMed

Chen, Lee Chuin; Ninomiya, Satoshi; Hiraoka, Kenzo

2016-06-01

Ion source pressure plays a significant role in the process of ionization and the subsequent ion transmission inside a mass spectrometer. Pressurizing the ion source to a gas pressure greater than atmospheric pressure is a relatively new approach that aims to further improve the performance of atmospheric pressure ionization sources. For example, under a super-atmospheric pressure environment, a stable electrospray can be sustained for liquid with high surface tension such as pure water, because of the suppression of electric discharge. Even for nano-electrospray ionization (nano-ESI), which is known to work with aqueous solution, its stability and sensitivity can also be enhanced, particularly in the negative mode when the ion source is pressurized. A brief review on the development of super-atmospheric pressure ion sources, including high-pressure electrospray, field desorption and superheated ESI, and the strategies to interface these ion sources to a mass spectrometer will be given. Using a recent ESI prototype with an operating temperature at 220 °C under 27 atm, we also demonstrate that it is possible to achieve an online Asp-specific protein digestion analysis in which the whole processes of digestion, ionization and MS acquisition could be completed on the order of a few seconds. This method is fast, and the reaction can even be monitored on a near-real-time basis. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Measurement of upper airway pressures in exercising horses with dorsal displacement of the soft palate.

PubMed

Rehder, R S; Ducharme, N G; Hackett, R P; Nielan, G J

1995-03-01

To determine whether abnormal airway pressures have a role in development of dorsal displacement of the soft palate (DDSP), measurements of tracheal and pharyngeal pressures were correlated with nasopharyngeal morphology in exercising horses. Exercising videoendoscopy and measurement of tracheal and pharyngeal pressures were used in 14 clinically normal horses and 19 horses with intermittent DDSP. The pressure signals were superimposed on the videoendoscope image, and both images were saved simultaneously on a videocassette for slow motion analysis to determine the instant displacement occurred in the respiratory cycle. Horses were submitted to an escalating 8-minute high-speed test with a maximal speed of 14 m/s. Compared with clinically normal horses, horses with intermittent DDSP did not have excessively negative inspiratory pressures during exercise. Eight horses displaced the soft palate during inspiration, 4 horses displaced it during expiration, and 7 displaced it by swallowing. Some horses displaced the soft palate at the beginning of the exercise trial, before reaching maximal speed, some horses displaced it at the peak speed, and some horses displaced it when slowing down. Epiglottic size in horses with DDSP was within normal limits, ruling out epiglottic hypoplasia as a cause of DDSP during exercise. Airway pressures were significantly (P < 0.002) altered after DDSP. Pharyngeal and tracheal inspiratory pressures were less negative, whereas pharyngeal expiratory pressure became less positive and tracheal expiratory pressure became more positive after displacement, suggesting a decrease in airflow and an increase in expiratory resistance in the upper airway.

Primary hypertension and special aspects of hypertension in older children and adolescents

PubMed Central

Ellis, Demetrius; Miyashita, Yosuke

2011-01-01

The prevalence of hypertension has increased at an accelerated rate in older children and adolescents. This has raised great concern about premature development of cardiovascular disease, which has major long-term health and financial implications. While obesity and sedentary habits largely explain this phenomenon, there are other social and cultural influences that may unmask genetic susceptibility to hypertension in the pediatric population. While it is essential to exclude numerous causes of secondary hypertension in every child, these disorders are not discussed in this review. Rather, the aim of this review is to familiarize pediatricians with casual and ambulatory blood pressure measurement, epidemiology, pathophysiology, and management of several common conditions that play a role in the development of hypertension in children and adolescents. Besides primary hypertension and obesity-related hypertension, emphasis is given to epidemiology, measurement of blood pressure, including ambulatory blood pressure monitoring, hypertension associated with drug use, teenage pregnancy, and video and computer games. Lastly, because pediatricians are increasingly confronted with special issues concerning the management of the hypertensive athlete, this topic is also addressed. PMID:24600275

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.

Quantitative analysis of a frequency-domain nonlinearity indicator.

PubMed

Reichman, Brent O; Gee, Kent L; Neilsen, Tracianne B; Miller, Kyle G

2016-05-01

In this paper, quantitative understanding of a frequency-domain nonlinearity indicator is developed. The indicator is derived from an ensemble-averaged, frequency-domain version of the generalized Burgers equation, which can be rearranged in order to directly compare the effects of nonlinearity, absorption, and geometric spreading on the pressure spectrum level with frequency and distance. The nonlinear effect is calculated using pressure-squared-pressure quadspectrum. Further theoretical development has given an expression for the role of the normalized quadspectrum, referred to as Q/S by Morfey and Howell [AIAA J. 19, 986-992 (1981)], in the spatial rate of change of the pressure spectrum level. To explore this finding, an investigation of the change in level for initial sinusoids propagating as plane waves through inviscid and thermoviscous media has been conducted. The decibel change with distance, calculated through Q/S, captures the growth and decay of the harmonics and indicates that the most significant changes in level occur prior to sawtooth formation. At large distances, the inviscid case results in a spatial rate of change that is uniform across all harmonics. For thermoviscous media, large positive nonlinear gains are observed but offset by absorption, which leads to a greater overall negative spatial rate of change for higher harmonics.

Chiari malformation may increase perivascular cerebrospinal fluid flow into the spinal cord: A subject-specific computational modelling study.

PubMed

Lloyd, Robert A; Fletcher, David F; Clarke, Elizabeth C; Bilston, Lynne E

2017-12-08

Syringomyelia is associated with Chiari I malformation, although the mechanistic link is unclear. Studies have suggested that cerebrospinal fluid enters the spinal cord via the perivascular spaces, and that changes in the timing of the subarachnoid pressures may increase flow into the spinal cord. This study aims to determine how Chiari malformation and syringomyelia alter the subarachnoid space pressures and hence perivascular flow. Subject-specific models of healthy controls (N = 9), Chiari patients with (N = 7) and without (N = 8) syringomyelia, were developed from magnetic resonance imaging (MRI), to simulate the subarachnoid pressures. These pressures were input to an idealised model of the perivascular space to evaluate potential differences in perivascular flow. Peak pressures in Chiari patients without a syrinx were higher than in controls (46% increase; p = .029) and arrived earlier in the cardiac cycle than both controls (2.58% earlier; p = .045) and syrinx patients (2.85% earlier; p = .045). The perivascular model predicted Chiari patients without a syrinx would have the greatest flow into the cord (p < .05) if the arterial pulse delay was between 4 and 10% of the cardiac cycle. Using phase-contrast MRI the mean arterial delay for all subjects was similar, and was estimated as 4.7 ± 0.2%. The perivascular pumping rate showed a strong positive correlation (R Adj 2 =0.85; p < .0001) with extended periods of high pressure that arrived earlier in the cardiac cycle, suggesting these pressure characteristics may play a role in syrinx development. Copyright © 2017 Elsevier Ltd. All rights reserved.

Blood borne hormones in a cross-talk between peripheral and brain mechanisms regulating blood pressure, the role of circumventricular organs.

PubMed

Ufnal, Marcin; Skrzypecki, Janusz

2014-04-01

Accumulating evidence suggests that blood borne hormones modulate brain mechanisms regulating blood pressure. This appears to be mediated by the circumventricular organs which are located in the walls of the brain ventricular system and lack the blood-brain barrier. Recent evidence shows that neurons of the circumventricular organs express receptors for the majority of cardiovascular hormones. Intracerebroventricular infusions of hormones and their antagonists is one approach to evaluate the influence of blood borne hormones on the neural mechanisms regulating arterial blood pressure. Interestingly, there is no clear correlation between peripheral and central effects of cardiovascular hormones. For example, angiotensin II increases blood pressure acting peripherally and centrally, whereas peripherally acting pressor catecholamines decrease blood pressure when infused intracerebroventricularly. The physiological role of such dual hemodynamic responses has not yet been clarified. In the paper we review studies on hemodynamic effects of catecholamines, neuropeptide Y, angiotensin II, aldosterone, natriuretic peptides, endothelins, histamine and bradykinin in the context of their role in a cross-talk between peripheral and brain mechanisms involved in the regulation of arterial blood pressure. Copyright © 2014 Elsevier Ltd. All rights reserved.

Computational analysis of aircraft pressure relief doors

NASA Astrophysics Data System (ADS)

Schott, Tyler

Modern trends in commercial aircraft design have sought to improve fuel efficiency while reducing emissions by operating at higher pressures and temperatures than ever before. Consequently, greater demands are placed on the auxiliary bleed air systems used for a multitude of aircraft operations. The increased role of bleed air systems poses significant challenges for the pressure relief system to ensure the safe and reliable operation of the aircraft. The core compartment pressure relief door (PRD) is an essential component of the pressure relief system which functions to relieve internal pressure in the core casing of a high-bypass turbofan engine during a burst duct over-pressurization event. The successful modeling and analysis of a burst duct event are imperative to the design and development of PRD's to ensure that they will meet the increased demands placed on the pressure relief system. Leveraging high-performance computing coupled with advances in computational analysis, this thesis focuses on a comprehensive computational fluid dynamics (CFD) study to characterize turbulent flow dynamics and quantify the performance of a core compartment PRD across a range of operating conditions and geometric configurations. The CFD analysis was based on a compressible, steady-state, three-dimensional, Reynolds-averaged Navier-Stokes approach. Simulations were analyzed, and results show that variations in freestream conditions, plenum environment, and geometric configurations have a non-linear impact on the discharge, moment, thrust, and surface temperature characteristics. The CFD study revealed that the underlying physics for this behavior is explained by the interaction of vortices, jets, and shockwaves. This thesis research is innovative and provides a comprehensive and detailed analysis of existing and novel PRD geometries over a range of realistic operating conditions representative of a burst duct over-pressurization event. Further, the study provides aircraft manufacturers with valuable insight into the impact that operating conditions and geometric configurations have on PRD performance and how the information can be used to assist future research and development of PRD design.

The critical role of the central nervous system (pro)renin receptor in regulating systemic blood pressure

PubMed Central

Xu, Quanbin; Jensen, Dane D.; Peng, Hua; Feng, Yumei

2016-01-01

The systemic renin–angiotensin system (RAS) has long been recognized as a critically important system in blood pressure (BP) regulation. However, extensive evidence has shown that a majority of RAS components are also present in many tissues and play indispensable roles in BP regulation. Here, we review evidence that RAS components, notably including the newly identified (pro)renin receptor (PRR), are present in the brain and are essential for the central regulation of BP. Binding of the PRR to its ligand, prorenin or renin, increases BP and promotes progression of cardiovascular diseases in an angiotensin II-dependent and -independent manner, establishing the PRR a promising antihypertensive drug target. We also review the existing PRR blockers, including handle region peptide and PRO20, and propose a rationale for blocking prorenin/PRR activation as a therapeutic approach that does not affect the actions of the PRR in vacuolar H+-ATPase and development. Finally, we summarize categories of currently available antihypertensive drugs and consider future perspectives. PMID:27113409

Ultrafiltration membrane for effective removal of chromium ions from potable water

NASA Astrophysics Data System (ADS)

Muthumareeswaran, M. R.; Alhoshan, Mansour; Agarwal, Gopal Prasad

2017-01-01

The objective of the present work was to investigate the efficacy of indigenously developed polyacrylonitrile (PAN) based ultrafiltration (UF) membrane for chromium ions removal from potable water. The hydrolyzed PAN membranes effectively rejected chromium anions in the feed ranging from 250 ppb to 400 ppm and a rejection of ≥90% was achieved for pH ≥ 7 at low chromate concentration (≤25 ppm) in feed. The rejection mechanism of chromium ions was strongly dependent on Donnan exclusion principle, while size exclusion principle for UF did not play a major role on ions rejection. Feed pH played a vital role in changing porosity of membrane, which influenced the retention behavior of chromate ions. Cross-flow velocity, pressure did not play significant role for ions rejection at low feed concentration. However, at higher feed concentration (≥400 ppm), concentration polarization became important and it reduced the chromate rejection to 32% at low cross flow and high pressure. Donnan steric-partitioning pore and dielectric exclusion model (DSPM-DE) was applied to evaluate the chromate ions transport through PAN UF membrane as a function of flux by using optimized model parameters and the simulated data matched well with experimental results.

NADPH Phagocyte Oxidase Knockout Mice Control Trypanosoma cruzi Proliferation, but Develop Circulatory Collapse and Succumb to Infection

PubMed Central

Macedo, Juan P.; Utsch, Lara; Tafuri, Wagner L.; Campagnole-Santos, Maria José; Alves, Rosana O.; Alves-Filho, José C. F.; Romanha, Alvaro J.; Cunha, Fernando Queiroz; Teixeira, Mauro M.; Radi, Rafael; Vieira, Leda Q.

2012-01-01

•NO is considered to be a key macrophage-derived cytotoxic effector during Trypanosoma cruzi infection. On the other hand, the microbicidal properties of reactive oxygen species (ROS) are well recognized, but little importance has been attributed to them during in vivo infection with T. cruzi. In order to investigate the role of ROS in T. cruzi infection, mice deficient in NADPH phagocyte oxidase (gp91phox −/− or phox KO) were infected with Y strain of T. cruzi and the course of infection was followed. phox KO mice had similar parasitemia, similar tissue parasitism and similar levels of IFN-γ and TNF in serum and spleen cell culture supernatants, when compared to wild-type controls. However, all phox KO mice succumbed to infection between day 15 and 21 after inoculation with the parasite, while 60% of wild-type mice were alive 50 days after infection. Further investigation demonstrated increased serum levels of nitrite and nitrate (NOx) at day 15 of infection in phox KO animals, associated with a drop in blood pressure. Treatment with a NOS2 inhibitor corrected the blood pressure, implicating NOS2 in this phenomenon. We postulate that superoxide reacts with •NO in vivo, preventing blood pressure drops in wild type mice. Hence, whilst superoxide from phagocytes did not play a critical role in parasite control in the phox KO animals, its production would have an important protective effect against blood pressure decline during infection with T. cruzi. PMID:22348160

Quantitative Evaluation of CART-Containing Cells in Urinary Bladder of Rats with Renovascular Hypertension

PubMed Central

Janiuk, I.; Kasacka, I.

2015-01-01

Recent biological advances make it possible to discover new peptides associated with hypertension. The cocaine- and amphetamine-regulated transcript (CART) is a known factor in appetite and feeding behaviour. Various lines of evidence suggest that this peptide participates not only in control of feeding behaviour but also in the regulation of the cardiovascular and sympathetic systems and blood pressure. The role of CART in blood pressure regulation led us to undertake a study aimed at analysing quantitative changes in CART-containing cells in urinary bladders (UB) of rats with renovascular hypertension. We used the Goldblatt model of arterial hypertension (two-kidney, one clip) to evaluate quantitative changes. This model provides researchers with a commonly used tool to analyse the renin-angiotensin system of blood pressure control and, eventually, to develop drugs for the treatment of chronic hypertension. The study was performed on sections of urinary bladders of rats after 3-, 14-, 28-, 42 and 91 days from hypertension induction. Immunohistochemical identification of CART cells was performed on paraffin for the UBs of all the study animals. CART was detected in the endocrine cells, especially numerous in the submucosa and muscularis layers, with a few found in the transitional epithelium and only occasionally in serosa. Hypertension significantly increased the number of CART-positive cells in the rat UBs. After 3 and 42 days following the procedure, statistically significantly higher numbers of CART-positive cells were identified in comparison with the control animals. The differences between the hypertensive rats and the control animals concerned not only the number density of CART-immunoreactive cells but also their localization. After a 6-week period, each of the rats subjected to the renal artery clipping procedure developed stable hypertension. CART appeared in numerous transitional epithelium cells. As this study provides novel findings, the question appears about the type of connection between hypertension and the functioning and activity of CART in the urinary tract (UT). The study gives rise to the assumption that high blood pressure can be a factor that intensifies CART secretion. In conclusion, the endocrine system of the urinary tract is modified by renovascular hypertension. This may affect the production of hormones and biologically active substances and contribute to the development of possible hypertension complications. In order to fully comprehend the role of the CART peptide in blood pressure regulation, further analyses are necessary. PMID:26150151

Quantitative evaluation of CART-containing cells in urinary bladder of rats with renovascular hypertension.

PubMed

Janiuk, I; Kasacka, I

2015-04-13

Recent biological advances make it possible to discover new peptides associated with hypertension. The cocaine- and amphetamine-regulated transcript (CART) is a known factor in appetite and feeding behaviour. Various lines of evidence suggest that this peptide participates not only in control of feeding behaviour but also in the regulation of the cardiovascular and sympathetic systems and blood pressure. The role of CART in blood pressure regulation led us to undertake a study aimed at analysing quantitative changes in CART-containing cells in urinary bladders (UB) of rats with renovascular hypertension. We used the Goldblatt model of arterial hypertension (two-kidney, one clip) to evaluate quantitative changes. This model provides researchers with a commonly used tool to analyse the renin-angiotensin system of blood pressure control and, eventually, to develop drugs for the treatment of chronic hypertension. The study was performed on sections of urinary bladders of rats after 3-, 14-, 28-, 42 and 91 days from hypertension induction. Immunohistochemical identification of CART cells was performed on paraffin for the UBs of all the study animals. CART was detected in the endocrine cells, especially numerous in the submucosa and muscularis layers, with a few found in the transitional epithelium and only occasionally in serosa. Hypertension significantly increased the number of CART-positive cells in the rat UBs. After 3 and 42 days following the procedure, statistically significantly higher numbers of CART-positive cells were identified in comparison with the control animals. The differences between the hypertensive rats and the control animals concerned not only the number density of CART-immunoreactive cells but also their localization. After a 6-week period, each of the rats subjected to the renal artery clipping procedure developed stable hypertension. CART appeared in numerous transitional epithelium cells. As this study provides novel findings, the question appears about the type of connection between hypertension and the functioning and activity of CART in the urinary tract (UT). The study gives rise to the assumption that high blood pressure can be a factor that intensifies CART secretion. In conclusion, the endocrine system of the urinary tract is modified by renovascular hypertension. This may affect the production of hormones and biologically active substances and contribute to the development of possible hypertension complications. In order to fully comprehend the role of the CART peptide in blood pressure regulation, further analyses are necessary.

Improving health related quality of life among rural hypertensive patients through the integrative strategy of health services delivery: a quasi-experimental trial from Chongqing, China.

PubMed

Miao, Yudong; Zhang, Liang; Sparring, Vibeke; Sandeep, Sandeep; Tang, Wenxi; Sun, Xiaowei; Feng, Da; Ye, Ting

2016-08-23

Integrative strategy of health services delivery has been proven to be effective in economically developed countries, where the healthcare systems have enough qualified primary care providers. However rural China lacks such providers to act as gatekeeper, besides, Chinese rural hypertensive patients are usually of old age, more likely to be exposed to health risk factors and they experience a greater socio-economic burden. All these Chinese rural setting specific features make the effectiveness of integrative strategy of health services in improving health related quality of life among Chinese rural hypertensive patients uncertain. In order to assess the impact of integrative strategy of health services delivery on health related quality of life among Chinese rural hypertensive patients, a two-year quasi-experimental trial was conducted in Chongqing, China. At baseline the sample enrolled 1006 hypertensive patients into intervention group and 420 hypertensive patients into control group. Physicians from village clinics, town hospitals and county hospitals worked collaboratively to deliver multidisciplinary health services for the intervention group, while physicians in the control group provided services without cooperation. The quality of life was studied by SF-36 Scale. Blood pressures were reported by town hospitals. The Difference-in-Differences model was used to estimate the differences in SF-36 score and blood pressure of both groups to assess the impact. The study showed that at baseline there was no statistical difference in SF-36 scores between both groups. While at follow-up the intervention group scored higher in overall SF-36, Role Physical, Body Pain, Social Functioning and Role Emotional than the control group. The Difference-in-Differences result demonstrated that there were statistical differences in SF-36 total score (p = 0.011), Role Physical (p = 0.027), Social Functioning (p = 0.000), Role Emotional (p = 0.002) between both groups. Integrative services delivery improved the score of SF-36 by 4.591 ± 1.794, and also improved the score in domains of Role Physical, Social Functioning and Role Emotional by 8.289 ± 3.753, 9.762 ± 2.019 and 12.534 ± 4.083, respectively. Patients in the intervention group obtained lower systolic blood pressure and diastolic blood pressure. Integrative strategy of health services delivery improved health related quality of life and blood pressure control among rural Chinese hypertensive patients. The Ethics Committee of Tongji Medical College, Huazhong University of Science and Technology, ChiCTR-OOR-14005563, Registered on 7 June 2011.

[Role of cerebral hemodynamics in the mechanism of development of acquired myopia in schoolchildren].

PubMed

Iastrebtseva, T A; Demidova, T E; Polikarpova, V E

2008-01-01

Rheoencephalography was used to study cerebral venous circulation in 199 schoolchildren aged 12-15 years who had emmetropia, pseudomyopia, and myopia. Tonometry was carried out in 39 persons. Cerebral venous hemodynamic dysfunction was more frequently encountered in schoolchildren with myopia than in those with emmetropia. Intraocular pressure was significantly higher only in schoolchildren with high myopia than in the controls.

Predicting Gang Fight Participation in a General Youth Sample via the HEW Youth Development Model's Community Program Impact Scales, Age, and Sex.

ERIC Educational Resources Information Center

Truckenmiller, James L.

The accurate prediction of violence has been in the spotlight of critical concern in recent years. To investigate the relative predictive power of peer pressure, youth perceived negative labeling, youth perceived access to educational and occupational roles, social alienation, self-esteem, sex, and age with regard to gang fight participation…

The Development of Conformity and Independence. Report from the Project on Role Theory Analysis of Peer-Teaching Techniques.

ERIC Educational Resources Information Center

Allen, Vernon L.; Newtson, Darren

Age trends in conformity and independence, using a sample of 366 children from the 1st, 4th, 7th, and 10th grades were investigated. Three types of stimuli were used: (1) visual judgments; (2) opinion statements; and (3) delay of gratification preferences. Age-trends were observed for unanimous peer pressure, adult influence, and peer pressure…

Accelerating rate calorimetry: A new technique for safety studies in lithium systems

NASA Technical Reports Server (NTRS)

Ebner, W. B.

1982-01-01

The role of exothermic reactions in battery test modes is discussed. The exothermic reactions are characterized with respect to their time-temperature and time-pressure behavior. Reactions occuring for any major exotherm were examined. The accelerating rate calorimetry methods was developed to study lithium cells susceptibility to thermal runaway reactions following certain abuse modes such as forced discharge into reversal and charging.

Carbon Dioxide Effects under Conditions of Raised Environmental Pressure

DTIC Science & Technology

1974-12-26

mechanics of respiration and in particular, the behavior of the respiratory gases. Carbon dioxide plays a major role in the physiology of the...of respiratory limitations and associated COg retention when divers are performing heavy, exhaustive work. In shallow habitat air diving using...combinations of air and normoxic nitrogen-oxygen breathing mixtures, evidence for the development of slight respiratory acidosis and CO2 retention has

The Role of Aldosterone in Obesity-Related Hypertension

PubMed Central

Kawarazaki, Wakako

2016-01-01

Obese subjects often have hypertension and related cardiovascular and renal diseases, and this has become a serious worldwide health problem. In obese subjects, impaired renal-pressure natriuresis causes sodium retention, leading to the development of salt-sensitive hypertension. Physical compression of the kidneys by visceral fat and activation of the sympathetic nervous system, renin–angiotensin systems (RAS), and aldosterone/mineralocorticoid receptor (MR) system are involved in this mechanism. Obese subjects often exhibit hyperaldosteronism, with increased salt sensitivity of blood pressure (BP). Adipose tissue excretes aldosterone-releasing factors, thereby stimulating aldosterone secretion independently of the systemic RAS, and aldosterone/MR activation plays a key role in the development of hypertension and organ damage in obesity. In obese subjects, both salt sensitivity of BP, enhanced by obesity-related metabolic disorders including aldosterone excess, and increased dietary sodium intake are closely related to the incidence of hypertension. Some salt sensitivity-related gene variants affect the risk of obesity, and together with salt intake, its combination is possibly associated with the development of hypertension in obese subjects. With high salt levels common in modern diets, salt restriction and weight control are undoubtedly important. However, not only MR blockade but also new diagnostic modalities and therapies targeting and modifying genes that are related to salt sensitivity, obesity, or RAS regulation are expected to prevent obesity and obesity-related hypertension. PMID:26927805

A note on the velocity derivative flatness factor in decaying HIT

NASA Astrophysics Data System (ADS)

Djenidi, L.; Danaila, L.; Antonia, R. A.; Tang, S.

2017-05-01

We develop an analytical expression for the velocity derivative flatness factor, F, in decaying homogenous and isotropic turbulence (HIT) starting with the transport equation of the third-order moment of the velocity increment and assuming self-preservation. This expression, fully consistent with the Navier-Stokes equations, relates F to the product between the second-order pressure derivative (∂2p /∂x2) and second-order moment of the longitudinal velocity derivative ((∂u/∂x ) 2), highlighting the role the pressure plays in the scaling of the fourth-order moment of the longitudinal velocity derivative. It is also shown that F has an upper bound which follows the integral of k*4Ep*(k* ) where Ep and k are the pressure spectrum and the wavenumber, respectively (the symbol * represents the Kolmogorov normalization). Direct numerical simulations of forced HIT suggest that this integral converges toward a constant as the Reynolds number increases.

Enhanced acoustic sensing through wave compression and pressure amplification in anisotropic metamaterials.

PubMed

Chen, Yongyao; Liu, Haijun; Reilly, Michael; Bae, Hyungdae; Yu, Miao

2014-10-15

Acoustic sensors play an important role in many areas, such as homeland security, navigation, communication, health care and industry. However, the fundamental pressure detection limit hinders the performance of current acoustic sensing technologies. Here, through analytical, numerical and experimental studies, we show that anisotropic acoustic metamaterials can be designed to have strong wave compression effect that renders direct amplification of pressure fields in metamaterials. This enables a sensing mechanism that can help overcome the detection limit of conventional acoustic sensing systems. We further demonstrate a metamaterial-enhanced acoustic sensing system that achieves more than 20 dB signal-to-noise enhancement (over an order of magnitude enhancement in detection limit). With this system, weak acoustic pulse signals overwhelmed by the noise are successfully recovered. This work opens up new vistas for the development of metamaterial-based acoustic sensors with improved performance and functionalities that are highly desirable for many applications.

The Pressure induced by salt crystallization in confinement.

PubMed

Desarnaud, J; Bonn, D; Shahidzadeh, N

2016-08-05

Salt crystallization is a major cause of weathering of rocks, artworks and monuments. Damage can only occur if crystals continue to grow in confinement, i.e. within the pore space of these materials, thus generating mechanical stress. We report the direct measurement, at the microscale, of the force exerted by growing alkali halide salt crystals while visualizing their spontaneous nucleation and growth. The experiments reveal the crucial role of the wetting films between the growing crystal and the confining walls for the development of the pressure. Our results suggest that the measured force originates from repulsion between the similarly charged confining wall and the salt crystal separated by a ~1.5 nm liquid film. Indeed, if the walls are made hydrophobic, no film is observed and no repulsive forces are detected. We also show that the magnitude of the induced pressure is system specific explaining why different salts lead to different amounts of damage to porous materials.

Hypertensive crisis in children.

PubMed

Chandar, Jayanthi; Zilleruelo, Gastón

2012-05-01

Hypertensive crisis is rare in children and is usually secondary to an underlying disease. There is strong evidence that the renin-angiotensin system plays an important role in the genesis of hypertensive crisis. An important principle in the management of children with hypertensive crisis is to determine if severe hypertension is chronic, acute, or acute-on-chronic. When it is associated with signs of end-organ damage such as encephalopathy, congestive cardiac failure or renal failure, there is an emergent need to lower blood pressures to 25-30% of the original value and then accomplish a gradual reduction in blood pressure. Precipitous drops in blood pressure can result in impairment of perfusion of vital organs. Medications commonly used to treat hypertensive crisis in children are nicardipine, labetalol and sodium nitroprusside. In this review, we discuss the pathophysiology, differential diagnosis and recent developments in management of hypertensive crisis in children.

Matching the needs of a nation: The strategic roles of indicators for decisionmaking

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

Peterson, P.J.

Indicators are important tools for communicating and making accessible scientific and technical information to policymakers and the general public. They therefore play an important role in transforming information into action. Worldwide, many initiatives are underway to construct indicators for a variety of purposes, including those for reporting on sustainable development. This paper briefly describes the attempts made so far, but stresses that the users of the indicators should play a greater role in indicator construction. In developing countries, a substantial lack of data has meant that specific policy formulation may develop without adequate technical input. In developed countries also, datamore » gaps may hinder policy formulation, implementation, and evaluation. However, the development of indicators as tools to assist in the management of hazardous wastes and toxic chemicals is still in the early stages of formulation. A more imaginative program of indicators and indices is required, where targets are well defined and the users clearly identified to assist in decision making, especially at the local and national levels. A broader range of pressure indicators, beyond hazardous wastes, is proposed to integrate toxic chemicals, emissions, and environmental and human health impacts. 39 refs., 3 figs.« less

Catheter-based renal denervation for treatment of resistant hypertension

PubMed Central

Hatipoglu, Emine; Ferro, Albert

2013-01-01

Hypertension is a common disease associated with important cardiovascular complications. Persistent blood pressure of 140/90 or higher despite combined use of a reninangiotensin system blocker, calcium channel blocker and a diuretic at highest tolerated doses constitutes resistant hypertension. Excess sympathetic activity plays an important pathogenic role in resistant hypertension in addition to contributing to the development of metabolic problems, in particular diabetes. Reduction of renal sympathetic activity by percutaneous catheter-based radiofrequency ablation via the renal arteries has been shown in several studies to decrease blood pressure in patients with resistant hypertension, and importantly is largely free of significant complications. However, longer term follow-up is required to confirm both long-term safety and efficacy. PMID:24175081

Hypertension in Developing Countries: A Major Challenge for the Future.

PubMed

Mohsen Ibrahim, M

2018-05-01

Outline recent epidemiologic data regarding hypertension in developing countries, distinguish differences from developed countries, and identify challenges in management and future perspectives. Increased sugar intake, air and noise pollution, and low birth weight are emerging hypertension risk factors. The major challenges in management are difficulties in accurate diagnosis of hypertension and adequate blood pressure control. In contrast to developed countries, hypertension prevalence rates are on the rise in developing countries with no improvement in awareness or control rates. The increasing burden of hypertension is largely attributable to behavioral factors, urbanization, unhealthy diet, obesity, social stress, and inactivity. Health authorities, medical societies, and drug industry can collaborate to improve hypertension control through education programs, public awareness campaigns, legislation to limit salt intake, encourage generic drugs, development and dissemination of national guidelines, and involving nurses and pharmacists in hypertension management. More epidemiologic data are needed in the future to identify reasons behind increased prevalence and poor blood pressure control and examine trends in prevalence, awareness, treatment, and control. National programs for better hypertension control based on local culture, economic characteristics, and available resources in the population are needed. The role of new tools for hypertension management should be tested in developing world.

[How does salt intake influence blood pressure? Associated aetiopathogenic mechanisms].

PubMed

Fernández-Llama, P; Calero, F

2017-12-15

Abundant evidence from epidemiological and experimental studies has established a link between salt and blood pressure. However, there is heterogeneity in the blood pressure responses of humans to changes in sodium intake. Those individuals in whom a severe, abrupt change in salt intake causes the least change in arterial pressure and are termed salt-resistant, whereas in those in whom this leads to large changes in blood pressure, are called salt sensitive. Classically, Guyton's theory of the pressure-natriuresis phenomenon has been accepted to explain the pressor effect of salt, as well as the fundamental role played by the different protein sodium transporters of the renal tubules. In recent years, new theories have emerged pointing to the possible role of the immune system and the existence of a third sodium store in the body as aetiopathogenic factors. Copyright © 2017 SEH-LELHA. Publicado por Elsevier España, S.L.U. All rights reserved.

Self-disclosure in eating disorders.

PubMed

Basile, B

2004-09-01

Secrecy and concealment are typical behaviours in individuals with eating problems. This study explored the relationship between eating-related problems and self-disclosure. It examined whether women with greater eating related problems were less willing to disclose. Different types of self-disclosure were calculated, considering disclosure related to body appearance and to restrained eating. The role of risk factors which concur to the development and maintenance of eating symptomatology was also explored. The Eating Symptoms Inventory was used to investigate the existence of an eventual eating symptomatology, self-disclosure was calculated through the Self-Disclosure Index, while a new scale was validated to assess a self-disclosure related to body image and eating attitudes. Other scales measured the influence of different risk factors, as body dissatisfaction, social pressure to be thin, and restrained eating. A significant inverse relationship was found between general self-disclosure and psychological aspects related to the practice of wrong weight control behaviours and risk factors as dieting, body dissatisfaction, and social pressure to be thin. The significant role of risk factors was confirmed in the development and maintenance of eating disturbances. Interesting results were found using the different self-disclosure indexes as mediators and moderators. Relevant differences were found between Dutch and Italians concerning to their eating attitudes and to the role of different risk factors. Some limits are the impossibility to generalize these findings and the use of a non clinical sample. Some new longitudinal studies should be done in this direction to deepen the relationship between self-disclosure and eating disorders.

Review of Full-Scale Docking Seal Testing Capabilities

NASA Technical Reports Server (NTRS)

Dunlap, Patrick H., Jr.; Penney, Nicholas; Wasowski, Janice L.; Daniels, Christopher C.; Steinetz, Bruce M.

2008-01-01

NASA is developing a new docking system to support future space exploration missions to low-Earth orbit, the Moon, and Mars. This mechanism, called the Low Impact Docking System (LIDS), is designed to connect pressurized space vehicles and structures including the Crew Exploration Vehicle, International Space Station, and lunar lander. NASA Glenn Research Center (GRC) is playing a key role in developing the main interface seal for this new docking system. These seals will be approximately 147 cm (58 in.) in diameter. To evaluate the performance of the seals under simulated operating conditions, NASA GRC is developing two new test rigs: a non-actuated version that will be used to measure seal leak rates and an actuated test rig that will be able to measure both seal leak rates and loads. Both test rigs will be able to evaluate the seals under seal-on-seal or seal-on-plate configurations at temperatures from -50 to 50 C (-58 to 122 F) under operational and pre-flight checkout pressure gradients in both aligned and misaligned conditions.

βENaC acts as a mechanosensor in renal vascular smooth muscle cells that contributes to renal myogenic blood flow regulation, protection from renal injury and hypertension.

PubMed

Drummond, Heather A; Stec, David E

2015-06-01

Pressure-induced constriction (also known as the "myogenic response") is an important mechanodependent response in small renal arteries and arterioles. The response is initiated by vascular smooth muscle cell (VSMC) stretch due to an increase in intraluminal pressure and leads to vasoconstriction. The myogenic response has two important roles as a mechanism of local blood flow autoregulation and protection against systemic blood pressure-induced microvascular damage. However, the molecular mechanisms underlying initiation of myogenic response are unresolved. Although several molecules have been considered initiators of the response, our laboratory has focused on the role of degenerin proteins because of their strong evolutionary link to mechanosensing in the nematode. Our laboratory has addressed the hypothesis that certain degenerin proteins act as mechanosensors in VSMCs. This article discusses the importance of a specific degenerin protein, β Epithelial Na + Channel (βENaC), in pressure-induced vasoconstriction, renal blood flow and susceptibility to renal injury. We propose that loss of the renal myogenic constrictor response delays the correction of renal blood flow that occurs with fluctuations in systemic pressure, which allows pressure swings to be transmitted to the microvasculature, thus increasing the susceptibility to renal injury and hypertension. The role of βENaC in myogenic regulation is independent of tubular βENaC and thus represents a non-tubular role for βENaC in renal-cardiovascular homeostasis.

Tenascin-C promotes chronic pressure overload-induced cardiac dysfunction, hypertrophy and myocardial fibrosis.

PubMed

Podesser, Bruno K; Kreibich, Maximilian; Dzilic, Elda; Santer, David; Förster, Lorenz; Trojanek, Sandra; Abraham, Dietmar; Krššák, Martin; Klein, Klaus U; Tretter, Eva V; Kaun, Christoph; Wojta, Johann; Kapeller, Barbara; Gonçalves, Inês Fonseca; Trescher, Karola; Kiss, Attila

2018-04-01

Left ventricular (LV) hypertrophy is characterized by cardiomyocyte hypertrophy and interstitial fibrosis ultimately leading to increased myocardial stiffness and reduced contractility. There is substantial evidence that the altered expression of matrix metalloproteinases (MMP) and Tenascin-C (TN-C) are associated with the progression of adverse LV remodeling. However, the role of TN-C in the development of LV hypertrophy because of chronic pressure overload as well as the regulatory role of TN-C on MMPs remains unknown. In a knockout mouse model of TN-C, we investigated the effect of 10 weeks of pressure overload using transverse aortic constriction (TAC). Cardiac function was determined by magnetic resonance imaging. The expression of MMP-2 and MMP-9, CD147 as well as myocardial fibrosis were assessed by immunohistochemistry. The expression of TN-C was assessed by RT-qPCR and ELISA. TN-C knockout mice showed marked reduction in fibrosis (P < 0.001) and individual cardiomyocytes size (P < 0.01), in expression of MMP-2 (P < 0.05) and MMP-9 (P < 0.001) as well as preserved cardiac function (P < 0.01) in comparison with wild-type mice after 10 weeks of TAC. In addition, CD147 expression was markedly increased under pressure overload (P < 0.01), irrespectively of genotype. TN-C significantly increased the expression of the markers of hypertrophy such as ANP and BNP as well as MMP-2 in H9c2 cells (P < 0.05, respectively). Our results are pointed toward a novel signaling mechanism that contributes to LV remodeling via MMPs upregulation, cardiomyocyte hypertrophy as well as myocardial fibrosis by TN-C under chronic pressure overload.

Modeling pressure-driven assembly of polymer coated nanoparticles

NASA Astrophysics Data System (ADS)

Lane, J. Matthew D.; Salerno, K. Michael; Grest, Gary S.; Fan, Hongyou

2017-06-01

High-pressure experiments have successfully produced a variety of gold nanostructures by compressing polymer coated spherical nanoparticles. We apply atomistic simulation to understand the role of the soft polymer response in determining the pressure-driven assembly of gold nanostructures. Quasi-isentropic experiments have shown that 1D, 2D and 3D nanostructures can be formed and recovered from dynamic compression of fcc superlattices of alkanethiol-coated gold nanocrystals on Sandia's Veloce pulsed power accelerator. Molecular modeling has shown that the dimensionality of the final structures depends on the orientation of the superlattice and the uniaxial loading. We describe the role of coating ligand length and grafting density, on ligand migration and deformation processes during pressure-driven coalescence of the cores into permanent nanowires, nanosheets and 3D structures. The role of uniaxial vs isotropic pressure and the effects of compression along various superlattice orientations will be discussed. Sandia National Laboratories is a multi-mission laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

The role of cerebrospinal fluid pressure in glaucoma and other ophthalmic diseases: A review

PubMed Central

Fleischman, David; Allingham, R. Rand

2013-01-01

Glaucoma is one of the most common causes of blindness in the world. Well-known risk factors include age, race, a positive family history and elevated intraocular pressures. A newly proposed risk factor is decreased cerebrospinal fluid pressure (CSFP). This concept is based on the notion that a pressure differential exists across the lamina cribrosa, which separates the intraocular space from the subarachnoid fluid space. In this construct, an increased translaminar pressure difference will occur with a relative increase in elevated intraocular pressure or a reduction in CSFP. This net change in pressure is proposed to act on the tissues within the optic nerve head, potentially contributing to glaucomatous optic neuropathy. Similarly, patients with ocular hypertension who have elevated CSFPs, would enjoy a relatively protective effect from glaucomatous damage. This review will focus on the current literature pertaining to the role of CSFP in glaucoma. Additionally, the authors examine the relationship between glaucoma and other known CSFP-related ophthalmic disorders. PMID:24227969

Pressure-Velocity Correlations in the Cove of a Leading Edge Slat

NASA Astrophysics Data System (ADS)

Wilkins, Stephen; Richard, Patrick; Hall, Joseph

2015-11-01

One of the major sources of aircraft airframe noise is related to the deployment of high-lift devices, such as leading-edge slats, particularly when the aircraft is preparing to land. As the engines are throttled back, the noise produced by the airframe itself is of great concern, as the aircraft is low enough for the noise to impact civilian populations. In order to reduce the aeroacoustic noise sources associated with these high lift devices for the next generation of aircraft an experimental investigation of the correlation between multi-point surface-mounted fluctuating pressures measured via flush-mounted microphones and the simultaneously measured two-component velocity field measured via Particle Image Velocimetry (PIV) is studied. The development of the resulting shear-layer within the slat cove is studied for Re =80,000, based on the wing chord. For low Mach number flows in air, the major acoustic source is a dipole acoustic source tied to fluctuating surface pressures on solid boundaries, such as the underside of the slat itself. Regions of high correlations between the pressure and velocity field near the surface will likely indicate a strong acoustic dipole source. In order to study the underlying physical mechanisms and understand their role in the development of aeroacoustic noise, Proper Orthogonal Decomposition (POD) by the method of snapshots is employed on the velocity field. The correlation between low-order reconstructions and the surface-pressure measurements are also studied.

The Role of Neural Reflexes in Control of the Cardiovascular System during Stress.

DTIC Science & Technology

1984-02-01

cold block increase arterial pressure but did not alter plasma renin activity or renin secretory rate in dogs with normal or high sodium diet...also found that these afferents may play a keen role in the regulation of renin scretoary rate during conditions which may alter cardiopulmonary blood ...important hormone in -. the regulation of arterial pressure . However, the role of the nervous system in controlling the release of vasopressin has not been

Blood pressure and cerebral white matter share common genetic factors in Mexican Americans.

PubMed

Kochunov, Peter; Glahn, David C; Lancaster, Jack; Winkler, Anderson; Karlsgodt, Kathrin; Olvera, Rene L; Curran, Joanna E; Carless, Melanie A; Dyer, Thomas D; Almasy, Laura; Duggirala, Ravi; Fox, Peter T; Blangero, John

2011-02-01

Elevated arterial pulse pressure and blood pressure (BP) can lead to atrophy of cerebral white matter (WM), potentially attributable to shared genetic factors. We calculated the magnitude of shared genetic variance between BP and fractional anisotropy of water diffusion, a sensitive measurement of WM integrity in a well-characterized population of Mexican Americans. The patterns of whole-brain and regional genetic overlap between BP and fractional anisotropy were interpreted in the context the pulse-wave encephalopathy theory. We also tested whether regional pattern in genetic pleiotropy is modulated by the phylogeny of WM development. BP and high-resolution (1.7 × 1.7 × 3 mm; 55 directions) diffusion tensor imaging data were analyzed for 332 (202 females; mean age 47.9 ± 13.3 years) members of the San Antonio Family Heart Study. Bivariate genetic correlation analysis was used to calculate the genetic overlap between several BP measurements (pulse pressure, systolic BP, and diastolic BP) and fractional anisotropy (whole-brain and regional values). Intersubject variance in pulse pressure and systolic BP exhibited a significant genetic overlap with variance in whole-brain fractional anisotropy values, sharing 36% and 22% of genetic variance, respectively. Regionally, shared genetic variance was significantly influenced by rates of WM development (r=-0.75; P=0.01). The pattern of genetic overlap between BP and WM integrity was generally in agreement with the pulse-wave encephalopathy theory. Our study provides evidence that a set of pleiotropically acting genetic factors jointly influence phenotypic variation in BP and WM integrity. The magnitude of this overlap appears to be influenced by phylogeny of WM development, suggesting a possible role for genotype-by-age interactions.

Cycle development and design for CO{sub 2} capture from flue gas by vacuum swing adsorption

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

Jun Zhang; Paul A. Webley

CO{sub 2} capture and storage is an important component in the development of clean power generation processes. One CO{sub 2} capture technology is gas-phase adsorption, specifically pressure (or vacuum) swing adsorption. The complexity of these processes makes evaluation and assessment of new adsorbents difficult and time-consuming. In this study, we have developed a simple model specifically targeted at CO{sub 2} capture by pressure swing adsorption and validated our model by comparison with data from a fully instrumented pilot-scale pressure swing adsorption process. The model captures non-isothermal effects as well as nonlinear adsorption and nitrogen coadsorption. Using the model and ourmore » apparatus, we have designed and studied a large number of cycles for CO{sub 2} capture. We demonstrate that by careful management of adsorption fronts and assembly of cycles based on understanding of the roles of individual steps, we are able to quickly assess the effect of adsorbents and process parameters on capture performance and identify optimal operating regimes and cycles. We recommend this approach in contrast to exhaustive parametric studies which tend to depend on specifics of the chosen cycle and adsorbent. We show that appropriate combinations of process steps can yield excellent process performance and demonstrate how the pressure drop, and heat loss, etc. affect process performance through their effect on adsorption fronts and profiles. Finally, cyclic temperature profiles along the adsorption column can be readily used to infer concentration profiles - this has proved to be a very useful tool in cyclic function definition. Our research reveals excellent promise for the application of pressure/vacuum swing adsorption technology in the arena of CO{sub 2} capture from flue gases. 20 refs., 6 figs., 2 tabs.« less

Validation of a 3D computational fluid-structure interaction model simulating flow through an elastic aperture.

PubMed

Quaini, A; Canic, S; Glowinski, R; Igo, S; Hartley, C J; Zoghbi, W; Little, S

2012-01-10

This work presents a validation of a fluid-structure interaction computational model simulating the flow conditions in an in vitro mock heart chamber modeling mitral valve regurgitation during the ejection phase during which the trans-valvular pressure drop and valve displacement are not as large. The mock heart chamber was developed to study the use of 2D and 3D color Doppler techniques in imaging the clinically relevant complex intra-cardiac flow events associated with mitral regurgitation. Computational models are expected to play an important role in supporting, refining, and reinforcing the emerging 3D echocardiographic applications. We have developed a 3D computational fluid-structure interaction algorithm based on a semi-implicit, monolithic method, combined with an arbitrary Lagrangian-Eulerian approach to capture the fluid domain motion. The mock regurgitant mitral valve corresponding to an elastic plate with a geometric orifice, was modeled using 3D elasticity, while the blood flow was modeled using the 3D Navier-Stokes equations for an incompressible, viscous fluid. The two are coupled via the kinematic and dynamic conditions describing the two-way coupling. The pressure, the flow rate, and orifice plate displacement were measured and compared with numerical simulation results. In-line flow meter was used to measure the flow, pressure transducers were used to measure the pressure, and a Doppler method developed by one of the authors was used to measure the axial displacement of the orifice plate. The maximum recorded difference between experiment and numerical simulation for the flow rate was 4%, the pressure 3.6%, and for the orifice displacement 15%, showing excellent agreement between the two. Copyright © 2011 Elsevier Ltd. All rights reserved.

Cycle development and design for CO2 capture from flue gas by vacuum swing adsorption.

PubMed

Zhang, Jun; Webley, Paul A

2008-01-15

CO2 capture and storage is an important component in the development of clean power generation processes. One CO2 capture technology is gas-phase adsorption, specifically pressure (or vacuum) swing adsorption. The complexity of these processes makes evaluation and assessment of new adsorbents difficult and time-consuming. In this study, we have developed a simple model specifically targeted at CO2 capture by pressure swing adsorption and validated our model by comparison with data from a fully instrumented pilot-scale pressure swing adsorption process. The model captures nonisothermal effects as well as nonlinear adsorption and nitrogen coadsorption. Using the model and our apparatus, we have designed and studied a large number of cycles for CO2 capture. We demonstrate that by careful management of adsorption fronts and assembly of cycles based on understanding of the roles of individual steps, we are able to quickly assess the effect of adsorbents and process parameters on capture performance and identify optimal operating regimes and cycles. We recommend this approach in contrast to exhaustive parametric studies which tend to depend on specifics of the chosen cycle and adsorbent. We show that appropriate combinations of process steps can yield excellent process performance and demonstrate how the pressure drop, and heat loss, etc. affect process performance through their effect on adsorption fronts and profiles. Finally, cyclic temperature profiles along the adsorption column can be readily used to infer concentration profiles-this has proved to be a very useful tool in cyclic function definition. Our research reveals excellent promise for the application of pressure/vacuum swing adsorption technology in the arena of CO2 capture from flue gases.

Functional analysis of a regulator of G-protein signaling CgRGS1 in the rubber tree anthracnose fungus Colletotrichum gloeosporioides.

PubMed

Liu, Zhi-Qiang; Wu, Man-Li; Ke, Zhi-Jian; Liu, Wen-Bo; Li, Xiao-Yu

2018-04-01

Colletotrichum gloeosporioides is the causal agent of rubber anthracnose, which is also one of the important biological factors threatening the development of natural rubber industry in the world. Regulators of G-protein signaling (RGS) are key negative regulators of G-proteins, which play important roles in growth, development and pathogenic processes of plant pathogens. In this study, a RGS gene CgRGS1 was functionally characterized in C. gloeosporioides. Compared to the wild type, the CgRGS1 deletion mutant had slow vegetative growth, reduced conidia with multi-end germination, low appressorium formation rate, high resistance to oxidative stress and SDS. Moreover, the mutant was sensitive to osmotic pressure and showed decreased virulence. In conclusion, CgRGS1 is involved in regulation of vegetative growth, conidiation, germination, appressorium formation, oxidative stress, osmotic pressure response and pathogenicity in C. gloeosporioides.

An Experimental Investigation of the Risk of Triggering Geological Disasters by Injection under Shear Stress

PubMed Central

Liu, Yixin; Xu, Jiang; Peng, Shoujian

2016-01-01

Fluid injection has been applied in many fields, such as hazardous waste deep well injection, forced circulation in geothermal fields, hydraulic fracturing, and CO2 geological storage. However, current research mainly focuses on geological data statistics and the dominating effects of pore pressure. There are only a few laboratory-conditioned studies on the role of drilling boreholes and the effect of injection pressure on the borehole wall. Through experimental phenomenology, this study examines the risk of triggering geological disasters by fluid injection under shear stress. We developed a new direct shear test apparatus, coupled Hydro-Mechanical (HM), to investigate mechanical property variations when an intact rock experienced step drilling borehole, fluid injection, and fluid pressure acting on the borehole and fracture wall. We tested the peak shear stress of sandstone under different experimental conditions, which showed that drilling borehole, water injection, and increased pore pressure led to the decrease in peak shear stress. Furthermore, as pore pressure increased, peak shear stress dispersion increased due to crack propagation irregularity. Because the peak shear stress changed during the fluid injection steps, we suggest that the risk of triggering geological disaster with injection under shear stress, pore, borehole, and fluid pressure should be considered. PMID:27929142

An Experimental Investigation of the Risk of Triggering Geological Disasters by Injection under Shear Stress.

PubMed

Liu, Yixin; Xu, Jiang; Peng, Shoujian

2016-12-08

Fluid injection has been applied in many fields, such as hazardous waste deep well injection, forced circulation in geothermal fields, hydraulic fracturing, and CO 2 geological storage. However, current research mainly focuses on geological data statistics and the dominating effects of pore pressure. There are only a few laboratory-conditioned studies on the role of drilling boreholes and the effect of injection pressure on the borehole wall. Through experimental phenomenology, this study examines the risk of triggering geological disasters by fluid injection under shear stress. We developed a new direct shear test apparatus, coupled Hydro-Mechanical (HM), to investigate mechanical property variations when an intact rock experienced step drilling borehole, fluid injection, and fluid pressure acting on the borehole and fracture wall. We tested the peak shear stress of sandstone under different experimental conditions, which showed that drilling borehole, water injection, and increased pore pressure led to the decrease in peak shear stress. Furthermore, as pore pressure increased, peak shear stress dispersion increased due to crack propagation irregularity. Because the peak shear stress changed during the fluid injection steps, we suggest that the risk of triggering geological disaster with injection under shear stress, pore, borehole, and fluid pressure should be considered.

The insertion-deletion polymorphism of the ACE gene is associated with increased blood pressure in women at the end of pregnancy.

PubMed

Reshetnikov, Evgeny A; Akulova, Ludmila Y; Dobrodomova, Irina S; Dvornyk, Volodymyr Y; Polonikov, Alexey V; Churnosov, Mikhail I

2015-09-01

Malfunctioning of the cardiovascular system during pregnancy may be responsible for adverse effects on the 'mother-fetus' system. The cardiovascular system of a pregnant woman develops adaptation to the increased load. Angiotensin-converting enzyme (ACE) is known to play an important role in the adaptation. The present study was designed to investigate whether the insertion-deletion (I/D) polymorphism of the ACE gene is associated with the level of arterial blood pressure in women before and during pregnancy. The level of blood pressure was measured in 591 Russian women (Central Russia) before and during (37-40 weeks term) pregnancy. The women were divided into three groups which were hypertensive, hypotensive, and normotensive according to blood pressure level. Genotyping of the ACE I/D polymorphism was performed using polymerase chain reaction (PCR) and amplified fragment length polymorphism assay. Women with genotype DD showed the highest blood pressure level both during and at the end of pregnancy (p<0.05). The highest frequencies of allele D and genotype DD were found in pregnant women in the hypertensive group. The deletion variant of the ACE gene is associated with high blood pressure level at the end of pregnancy. © The Author(s) 2013.

The role of ontogeny in physiological tolerance: decreasing hydrostatic pressure tolerance with development in the northern stone crab Lithodes maja

PubMed Central

Munro, Catriona; Morris, James P.; Brown, Alastair; Hauton, Chris; Thatje, Sven

2015-01-01

Extant deep-sea invertebrate fauna represent both ancient and recent invasions from shallow-water habitats. Hydrostatic pressure may present a significant physiological challenge to organisms seeking to colonize deeper waters or migrate ontogenetically. Pressure may be a key factor contributing to bottlenecks in the radiation of taxa and potentially drive speciation. Here, we assess shifts in the tolerance of hydrostatic pressure through early ontogeny of the northern stone crab Lithodes maja, which occupies a depth range of 4–790 m in the North Atlantic. The zoea I, megalopa and crab I stages were exposed to hydrostatic pressures up to 30.0 MPa (equivalent of 3000 m depth), and the relative fold change of genes putatively coding for the N-methyl-d-aspartate receptor-regulated protein 1 (narg gene), two heat-shock protein 70 kDa (HSP70) isoforms and mitochondrial Citrate Synthase (CS gene) were measured. This study finds a significant increase in the relative expression of the CS and hsp70a genes with increased hydrostatic pressure in the zoea I stage, and an increase in the relative expression of all genes with increased hydrostatic pressure in the megalopa and crab I stages. Transcriptional responses are corroborated by patterns in respiratory rates in response to hydrostatic pressure in all stages. These results suggest a decrease in the acute high-pressure tolerance limit as ontogeny advances, as reflected by a shift in the hydrostatic pressure at which significant differences are observed. PMID:26041343

The role of ontogeny in physiological tolerance: decreasing hydrostatic pressure tolerance with development in the northern stone crab Lithodes maja.

PubMed

Munro, Catriona; Morris, James P; Brown, Alastair; Hauton, Chris; Thatje, Sven

2015-06-22

Extant deep-sea invertebrate fauna represent both ancient and recent invasions from shallow-water habitats. Hydrostatic pressure may present a significant physiological challenge to organisms seeking to colonize deeper waters or migrate ontogenetically. Pressure may be a key factor contributing to bottlenecks in the radiation of taxa and potentially drive speciation. Here, we assess shifts in the tolerance of hydrostatic pressure through early ontogeny of the northern stone crab Lithodes maja, which occupies a depth range of 4-790 m in the North Atlantic. The zoea I, megalopa and crab I stages were exposed to hydrostatic pressures up to 30.0 MPa (equivalent of 3000 m depth), and the relative fold change of genes putatively coding for the N-methyl-D-aspartate receptor-regulated protein 1 (narg gene), two heat-shock protein 70 kDa (HSP70) isoforms and mitochondrial Citrate Synthase (CS gene) were measured. This study finds a significant increase in the relative expression of the CS and hsp70a genes with increased hydrostatic pressure in the zoea I stage, and an increase in the relative expression of all genes with increased hydrostatic pressure in the megalopa and crab I stages. Transcriptional responses are corroborated by patterns in respiratory rates in response to hydrostatic pressure in all stages. These results suggest a decrease in the acute high-pressure tolerance limit as ontogeny advances, as reflected by a shift in the hydrostatic pressure at which significant differences are observed. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Gender differences in pressure-natriuresis and renal autoregulation: role of the Angiotensin type 2 receptor.

PubMed

Hilliard, Lucinda M; Nematbakhsh, Mehdi; Kett, Michelle M; Teichman, Elleesha; Sampson, Amanda K; Widdop, Robert E; Evans, Roger G; Denton, Kate M

2011-02-01

Sexual dimorphism in arterial pressure regulation has been observed in humans and animal models. The mechanisms underlying this gender difference are not fully known. Previous studies in rats have shown that females excrete more salt than males at a similar arterial pressure. The renin-angiotensin system is a powerful regulator of arterial pressure and body fluid volume. This study examined the role of the angiotensin type 2 receptor (AT₂R) in pressure-natriuresis in male and female rats because AT₂R expression has been reported to be enhanced in females. Renal function was examined at renal perfusion pressures of 120, 100, and 80 mm Hg in vehicle-treated and AT₂R antagonist-treated (PD123319; 1 mg/kg/h) groups. The pressure-natriuresis relationship was gender-dependent such that it was shifted upward in female vs male rats (P < 0.001). AT₂R blockade modulated the pressure-natriuresis relationship, shifting the curve downward in male (P < 0.01) and female (P < 0.01) rats to a similar extent. In females, AT₂R blockade also reduced the lower end of the autoregulatory range of renal blood flow (P < 0.05) and glomerular filtration rate (P < 0.01). Subsequently, the renal blood flow response to graded angiotensin II infusion was also measured with and without AT₂R blockade. We found that AT₂R blockade enhanced the renal vasoconstrictor response to angiotensin II in females but not in males (P < 0.05). In conclusion, the AT₂R modulates pressure-natriuresis, allowing the same level of sodium to be excreted at a lower pressure in both genders. However, a gender-specific role for the AT₂R in renal autoregulation was evident in females, which may be a direct vascular AT₂R effect.

Carbon dioxide/brine wettability of porous sandstone versus solid quartz: An experimental and theoretical investigation.

PubMed

Alnili, Firas; Al-Yaseri, Ahmed; Roshan, Hamid; Rahman, Taufiq; Verall, Michael; Lebedev, Maxim; Sarmadivaleh, Mohammad; Iglauer, Stefan; Barifcani, Ahmed

2018-08-15

Wettability plays an important role in underground geological storage of carbon dioxide because the fluid flow and distribution mechanism within porous media is controlled by this phenomenon. CO 2 pressure, temperature, brine composition, and mineral type have significant effects on wettability. Despite past research on this subject, the factors that control the wettability variation for CO 2 /water/minerals, particularly the effects of pores in the porous substrate on the contact angle at different pressures, temperatures, and salinities, as well as the physical processes involved are not fully understood. We measured the contact angle of deionised water and brine/CO 2 /porous sandstone samples at different pressures, temperatures, and salinities. Then, we compared the results with those of pure quartz. Finally, we developed a physical model to explain the observed phenomena. The measured contact angle of sandstone was systematically greater than that of pure quartz because of the pores present in sandstone. Moreover, the effect of pressure and temperature on the contact angle of sandstone was similar to that of pure quartz. The results showed that the contact angle increases with increase in temperature and pressure and decreases with increase in salinity. Copyright © 2018 Elsevier Inc. All rights reserved.

Identification of canine coronary resistance and intramyocardial compliance on the basis of the waterfall model.

PubMed

Burattini, R; Sipkema, P; van Huis, G A; Westerhof, N

1985-01-01

This study was performed to elucidate the effects of cardiac contraction on coronary pressure-flow relations. On the basis of the waterfall mechanism, a lumped model of the coronary arterial system is presented consisting of a proximal (epicardial) compliance, a coronary resistance, and an intramyocardial compliance. A "back"-pressure, assumed to be proportional (constant k) to left ventricular pressure, impedes flow. From steady-state measurements of circumflex coronary artery flow and inflow pressure, together with left ventricular pressure, the values of the three model parameters and the constant k have been estimated. In the control condition proximal compliance is found to be 1.7 X 10(-12) m4s2kg-1, intramyocardial compliance 110 X 10(-12)m4s2kg-1, and resistance 7.5 X 10(9) kgm-4s-1. The proportionality constant k is close to unity. Effects of changes in left ventricular pressure and inflow pressure and the effect of vasoactive drugs on the parameters are also investigated. Changes in coronary resistance are always opposite to changes in intramyocardial compliance. Sensitivity analysis showed that epicardial compliance plays its major role during isovolumic contraction and relaxation; resistance plays a role throughout the cardiac cycle but is more important in diastole than in systole, whereas intramyocardial compliance plays a role in systole and in early diastole.

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

Gravitropism in Higher Plant Shoots 1

PubMed Central

Mueller, Wesley J.; Salisbury, Frank B.; Blotter, P. Thomas

1984-01-01

Dimensional changes during gravitropic bending of cocklebur (Xanthium strumarium L.) dicot stems were measured using techniques of stereo photogrammetry. The differential growth is from an increased growth rate on the bottom of the stem and a stopping or contraction of the top. Contraction of the top was especially evident upon release and immediate bending of horizontal stems that had been restrained between stiff wires for 36 hours. The energy for this could have been stored in both the top and bottom, since the bottom elongated, and the top contracted. Forces developed during bending were measured by fastening a stem tip to the end of a bar with attached strain gauges and recording electrical output from the strain gauges. Restrained mature cocklebur stems continued to accumulate potential energy for bending for about 120 hours, after which the recorded force reached a maximum. Pressures within castor bean (Ricinus communis L.) stems were also measured with 3.5-millimeter diameter pressure transducers. As expected, the pressure on the bottom of the restrained plants increased with time; pressures decreased in vertical controls, tops of restrained stems, and bottoms of free-bending stems. Pressures increased in tops of free-bending stems. When restrained plants were released, pressure on the bottom decreased and pressure on the top increased. Results suggest a possible role for cell contraction in the top of stems bending upward in response to gravity. Images Fig. 5 Fig. 11 PMID:16663987

Mechanical regulation of chondrogenesis

PubMed Central

2013-01-01

Mechanical factors play a crucial role in the development of articular cartilage in vivo. In this regard, tissue engineers have sought to leverage native mechanotransduction pathways to enhance in vitro stem cell-based cartilage repair strategies. However, a thorough understanding of how individual mechanical factors influence stem cell fate is needed to predictably and effectively utilize this strategy of mechanically-induced chondrogenesis. This article summarizes some of the latest findings on mechanically stimulated chondrogenesis, highlighting several new areas of interest, such as the effects of mechanical stimulation on matrix maintenance and terminal differentiation, as well as the use of multifactorial bioreactors. Additionally, the roles of individual biophysical factors, such as hydrostatic or osmotic pressure, are examined in light of their potential to induce mesenchymal stem cell chondrogenesis. An improved understanding of biomechanically-driven tissue development and maturation of stem cell-based cartilage replacements will hopefully lead to the development of cell-based therapies for cartilage degeneration and disease. PMID:23809493

Education and Work-Family Conflict: Explanations, Contingencies and Mental Health Consequences

ERIC Educational Resources Information Center

Schieman, Scott; Glavin, Paul

2011-01-01

Using data from a representative sample of American workers, we examine the association between education and work-to-family conflict--a form of inter-role conflict in which role pressures from each domain are incompatible in some way. The well-educated tend to occupy professional jobs with more income and pressures, and experience more…

A Procedure to Discriminate Between Successful and Unsuccessful Pressure Groups Which Have an Interest in Education. Final Report.

ERIC Educational Resources Information Center

Gustafson, Thomas John

A pilot study was designed to explore the nature of pressure groups interested in education and to determine characteristics common to those groups. Background material is presented covering the history of pressure groups in the U.S., the social structure in which pressure groups must operate, and the role of pressure groups in the decision-making…

Advances in Probes and Methods for Clinical EPR Oximetry

PubMed Central

Hou, Huagang; Khan, Nadeem; Jarvis, Lesley A.; Chen, Eunice Y.; Williams, Benjamin B.; Kuppusamy, Periannan

2015-01-01

EPR oximetry, which enables reliable, accurate, and repeated measurements of the partial pressure of oxygen in tissues, provides a unique opportunity to investigate the role of oxygen in the pathogenesis and treatment of several diseases including cancer, stroke, and heart failure. Building on significant advances in the in vivo application of EPR oximetry for small animal models of disease, we are developing suitable probes and instrumentation required for use in human subjects. Our laboratory has established the feasibility of clinical EPR oximetry in cancer patients using India ink, the only material presently approved for clinical use. We now are developing the next generation of probes, which are both superior in terms of oxygen sensitivity and biocompatibility including an excellent safety profile for use in humans. Further advances include the development of implantable oxygen sensors linked to an external coupling loop for measurements of deep-tissue oxygenations at any depth, overcoming the current limitation of 10 mm. This paper presents an overview of recent developments in our ability to make meaningful measurements of oxygen partial pressures in human subjects under clinical settings. PMID:24729217

Does leptin cause an increase in blood pressure in animals and humans?

PubMed

Simonds, Stephanie E; Pryor, Jack T; Cowley, Michael A

2017-01-01

Cardiovascular diseases (CVDs) are the number one cause of death globally. The risk for the development of CVDs is significantly increased in obesity. Leptin, the product of white adipose tissue, appears to contribute to the development of CVDs in obesity. Here, we discuss the premise that leptin engages the sympathetic nervous system and contributes to elevated blood pressure (BP) developing in obesity. The long-term regulation of BP is dependent on the activity of the autonomic nervous system and specifically the sympathetic nervous system. Sympathetic nerve activity is significantly increased in obese rodents and humans. Leptin increases sympathetic nerve activity in rodents and humans; however, leptin only consistently increases BP chronically in rodents. The ability of leptin to increase BP in rodents is via both hypothalamic and extrahypothalamic regions. In leptin-deficient and leptin receptor-deficient humans, leptin appears to be the key reason for decreased systolic BP. However, in other research conducted in humans, chronic administration of leptin does not elevate BP. Further research into the role of leptin in the development of CVDs, especially in humans, needs to be conducted.

A prospective study of gait related risk factors for exercise-related lower leg pain.

PubMed

Willems, T M; De Clercq, D; Delbaere, K; Vanderstraeten, G; De Cock, A; Witvrouw, E

2006-01-01

The purpose of this study was to determine prospectively gait related risk factors for exercise-related lower leg pain (ERLLP) in 400 physical education students. Static lower leg alignment was determined, and 3D gait kinematics combined with plantar pressure profiles were collected. After this evaluation, all sports injuries were registered by the same sports physician during the duration of the study. Forty six subjects developed ERLLP and 29 of them developed bilateral symptoms thus giving 75 symptomatic lower legs. Bilateral lower legs of 167 subjects who developed no injuries in the lower extremities served as controls. Cox regression analysis revealed that subjects who developed ERLLP had an altered running pattern before the injury compared to the controls and included (1) a significantly more central heel-strike, (2) a significantly increased pronation, accompanied with more pressure underneath the medial side of the foot, and (3) a significantly more lateral roll-off. These findings suggest that altered biomechanics play a role in the genesis of ERLLP and thus should be considered in prevention and rehabilitation.

Bounding the Spacecraft Atmosphere Design Space for Future Exploration Missions

NASA Technical Reports Server (NTRS)

Lange, Kevin E.; Perka, Alan T.; Duffield, Bruce E.; Jeng, Frank F.

2005-01-01

The selection of spacecraft and space suit atmospheres for future human space exploration missions will play an important, if not critical, role in the ultimate safety, productivity, and cost of such missions. Internal atmosphere pressure and composition (particularly oxygen concentration) influence many aspects of spacecraft and space suit design, operation, and technology development. Optimal atmosphere solutions must be determined by iterative process involving research, design, development, testing, and systems analysis. A necessary first step in this process is the establishment of working bounds on the atmosphere design space.

Nosocomial infections—a new approach towards preventive medicine using plasmas

NASA Astrophysics Data System (ADS)

Morfill, G. E.; Shimizu, T.; Steffes, B.; Schmidt, H.-U.

2009-11-01

A new, very efficient, large area scalable and robust electrode design for plasma production in air at atmosphere pressures has been developed and tested. This has made the development of a 'plasma dispenser' for hospital disinfection possible, which has certain advantages over current fluid disinfection systems. The properties of this device are presented, in particular the bactericidal and fungicidal efficiency, and the advantages are described. Such plasma dispensers could play an important role in the future fight against the alarming and growing threat posed by nosocomial (=hospital and community associated) bacterial infections.

The relation of blood pressure and carotid intima-media thickness with the glutathione cycle in a young bi-ethnic population: the African-PREDICT study.

PubMed

Myburgh, Caitlynd; Huisman, Hugo W; Mels, Catharina M C

2018-04-01

Oxidative stress has been implicated in the development of hypertension, arterial stiffness and atherosclerosis. Optimal functioning of the enzymatic antioxidant system is central to prevent increased oxidative stress and its consequences. We aimed to investigate the relationships of ambulatory blood pressure and carotid intima-media thickness with enzyme activities of the glutathione cycle in 396 young, black and white South Africans of the African-PREDICT study. Ambulatory blood pressure and carotid intima-media thickness were measured and glutathione peroxidase and glutathione reductase activities were analyzed. Black participants had higher reactive oxygen species (men: p = 0.019; women: borderline p = 0.064) and total glutathione (both p < 0.001), but lower glutathione peroxidase activity and total antioxidant status (all p < 0.001). In black men, ambulatory pulse pressure was negatively associated with glutathione peroxidase activity (R 2  = 0.19; β = -0.25; p = 0.06). Black and white women displayed positive associations of ambulatory systolic blood pressure (black: R 2  = 0.25; β = 0.21; p = 0.048; white: R 2  = 0.44; β = 0.18; p = 0.016) with glutathione reductase activity, whereas white men displayed a positive association of ambulatory pulse pressure with glutathione reductase activity (R 2  = 0.25; β = 0.29; p = 0.01). The lower glutathione peroxidase activity and total antioxidant status, the higher reactive oxygen species, as well as the negative association between ambulatory pulse pressure and glutathione peroxidase activity in the black men suggest that oxidative stress may be associated with early vascular changes in this group. In the other three groups, the positive associations of blood pressure with glutathione reductase activity suggest a possible role for adequate glutathione reductase activity in preventing or delaying the development of hypertension.

Expansion of a compressible gas bubble in Stokes flow

NASA Astrophysics Data System (ADS)

Pozrikidis, C.

2001-09-01

The flow-induced deformation of an inviscid bubble occupied by a compressible gas and suspended in an ambient viscous liquid is considered at low Reynolds numbers with particular reference to the pressure developing inside the bubble. Ambient fluid motion alters the bubble pressure with respect to that established in the quiescent state, and requires the bubble to expand or contract according to an assumed equation of state. When changes in the bubble volume are prohibited by a global constraint on the total volume of the flow, the ambient pressure is modified while the bubble pressure remains constant during the deformation. A numerical method is developed for evaluating the pressure inside a two-dimensional bubble in an ambient Stokes flow on the basis of the normal component of the interfacial force balance involving the capillary pressure, the normal viscous stress, and the pressure at the free surface on the side of the liquid; the last is computed by evaluating a strongly singular integral. Dynamical simulations of bubble deformation are performed using the boundary integral method properly implemented to remove the multiplicity of solutions due to the a priori unknown rate of expansion, and three particular problems are discussed in detail: the shrinkage of a bubble at a specified rate, the deformation of a bubble subject to simple shear flow, and the deformation of a bubble subject to a purely elongational flow. In the case of shrinkage, it is found that the surface tension plays a critical role in determining the behaviour of the bubble pressure near the critical time when the bubble disappears. In the case of shear or elongational flow, it is found that the bubble contracts during an initial period of deformation from the circular shape, and then it expands to obtain a stationary shape whose area is higher than that assumed in the quiescent state. Expansion may destabilize the bubble by raising the capillary number above the critical threshold under which stationary shapes can be found.

Using AFM to probe the complexation of DNA with anionic lipids mediated by Ca(2+): the role of surface pressure.

PubMed

Luque-Caballero, Germán; Martín-Molina, Alberto; Sánchez-Treviño, Alda Yadira; Rodríguez-Valverde, Miguel A; Cabrerizo-Vílchez, Miguel A; Maldonado-Valderrama, Julia

2014-04-28

Complexation of DNA with lipids is currently being developed as an alternative to classical vectors based on viruses. Most of the research to date focuses on cationic lipids owing to their spontaneous complexation with DNA. Nonetheless, recent investigations have revealed that cationic lipids induce a large number of adverse effects on DNA delivery. Precisely, the lower cytotoxicity of anionic lipids accounts for their use as a promising alternative. However, the complexation of DNA with anionic lipids (mediated by cations) is still in early stages and is not yet well understood. In order to explore the molecular mechanisms underlying the complexation of anionic lipids and DNA we proposed a combined methodology based on the surface pressure-area isotherms, Gibbs elasticity and Atomic Force Microscopy (AFM). These techniques allow elucidation of the role of the surface pressure in the complexation and visualization of the interfacial aggregates for the first time. We demonstrate that the DNA complexes with negatively charged model monolayers (DPPC/DPPS 4 : 1) only in the presence of Ca(2+), but is expelled at very high surface pressures. Also, according to the Gibbs elasticity plot, the complexation of lipids and DNA implies a whole fluidisation of the monolayer and a completely different phase transition map in the presence of DNA and Ca(2+). AFM imaging allows identification for the first time of specific morphologies associated with different packing densities. At low surface coverage, a branched net like structure is observed whereas at high surface pressure fibers formed of interfacial aggregates appear. In summary, Ca(2+) mediates the interaction between DNA and negatively charged lipids and also the conformation of the ternary system depends on the surface pressure. Such observations are important new generic features of the interaction between DNA and anionic lipids.

Elevated blood pressure in the developing world: a role for clinical pharmacists.

PubMed

Smith, Michael T; Monahan, Megan P; Nelson, Paige; Moruzzi, Matthew; DeLucenay, Alexander J; Birnie, Christine R

2017-09-19

The objective of this study was to evaluate the prevalence and patient knowledge of elevated blood pressure amongst a cross-section of patients in underserved communities in three selected low-income countries worldwide: El Salvador, India and Kenya. Mobile medical clinics were established as part of medical mission trips in El Salvador, India and Kenya. Willing male and female patients, at least 25 years of age, who presented at each clinic were screened for elevated blood pressure, including 332 patients in El Salvador, 847 patients in India and 160 patients in Kenya. Patients were classified into Stage I or II elevated blood pressure based on modified JNCVII guidelines. A questionnaire was completed regarding their knowledge about the existence and management of their disease state. Of the 1339 patients screened, 368 presented with elevated blood pressure (27%). Of these patients, 147 had been previously informed of hypertension or an elevated blood pressure (39.9%), 28 reported receiving antihypertensive medication (7.6%) and 24 reported awareness of non-pharmaceutical treatment options (6.5%). In Kenya, 81 patients were screened in a rural setting and 79 in an urban setting. Patients demonstrating controlled blood pressure were 63 (78%) and 38 (48%), respectively, demonstrating a significant difference between the rural versus urban settings (P = 0.00359). All regions demonstrated similar trends in the prevalence of elevated blood pressure, highlighting the need for increased disease state education in these regions. © 2017 Royal Pharmaceutical Society.

Possible role of thromboxane A2 in remote hind limb preconditioning-induced cardioprotection.

PubMed

Sharma, Roohani; Randhawa, Puneet Kaur; Singh, Nirmal; Jaggi, Amteshwar Singh

2016-01-01

Remote hind limb preconditioning (RIPC) is a protective strategy in which short episodes of ischemia and reperfusion in a remote organ (hind limb) protects the target organ (heart) against sustained ischemic reperfusion injury. The present study was designed to investigate the possible role of thromboxane A2 in RIPC-induced cardioprotection in rats. Remote hind limb preconditioning was performed by four episodes of 5 min of inflation and 5 min of deflation of pressure cuff. Occlusion of the hind limb with blood pressure cuff is most feasible, non-invasive, clinically relevant, and safe method for inducing RIPC. Isolated rat hearts were perfused on Langendorff apparatus and were subjected to global ischemia for 30 min followed by 120-min reperfusion. The levels of lactate dehydrogenase (LDH) and creatine kinase (CK) were measured in coronary effluent to assess the degree of myocardial injury. The extent of myocardial infarct size along with the functional parameters including left ventricular developed pressure (LVDP), dp/dtmax, and dp/dtmin were also measured. Ozagrel (thromboxane synthase inhibitor) and seratrodast (thromboxane A2 receptor antagonist) were employed as pharmacological modulators of thromboxane A2. Remote hind limb preconditioning significantly attenuated ischemia/reperfusion-induced myocardial injury and produced cardioprotective effects. However, administration of ozagrel and seratrodast completely abolished the cardioprotective effects of RIPC suggesting the key role of thromboxane A2 in RIPC-induced cardioprotection. It may be concluded that brief episodes of preconditioning ischemia and reperfusion activates the thromboxane synthase enzyme that produces thromboxane A2, which may elicit cardioprotection either involving humoral or neurogenic pathway.

Reactive oxygen species, vascular Noxs, and hypertension: focus on translational and clinical research.

PubMed

Montezano, Augusto C; Touyz, Rhian M

2014-01-01

Reactive oxygen species (ROS) are signaling molecules that are important in physiological processes, including host defense, aging, and cellular homeostasis. Increased ROS bioavailability and altered redox signaling (oxidative stress) have been implicated in the onset and/or progression of chronic diseases, including hypertension. Although oxidative stress may not be the only cause of hypertension, it amplifies blood pressure elevation in the presence of other pro-hypertensive factors, such as salt loading, activation of the renin-angiotensin-aldosterone system, and sympathetic hyperactivity, at least in experimental models. A major source for ROS in the cardiovascular-renal system is a family of nicotinamide adenine dinucleotide phosphate oxidases (Noxs), including the prototypic Nox2-based Nox, and Nox family members: Nox1, Nox4, and Nox5. Although extensive experimental data support a role for increased ROS levels and altered redox signaling in the pathogenesis of hypertension, the role in clinical hypertension is unclear, as a direct causative role of ROS in blood pressure elevation has yet to be demonstrated in humans. Nevertheless, what is becoming increasingly evident is that abnormal ROS regulation and aberrant signaling through redox-sensitive pathways are important in the pathophysiological processes which is associated with vascular injury and target-organ damage in hypertension. There is a paucity of clinical information related to the mechanisms of oxidative stress and blood pressure elevation, and a few assays accurately measure ROS directly in patients. Such further ROS research is needed in humans and in the development of adequately validated analytical methods to accurately assess oxidative stress in the clinic.

Loss of Notch3 Signaling in Vascular Smooth Muscle Cells Promotes Severe Heart Failure Upon Hypertension.

PubMed

Ragot, Hélène; Monfort, Astrid; Baudet, Mathilde; Azibani, Fériel; Fazal, Loubina; Merval, Régine; Polidano, Evelyne; Cohen-Solal, Alain; Delcayre, Claude; Vodovar, Nicolas; Chatziantoniou, Christos; Samuel, Jane-Lise

2016-08-01

Hypertension, which is a risk factor of heart failure, provokes adaptive changes at the vasculature and cardiac levels. Notch3 signaling plays an important role in resistance arteries by controlling the maturation of vascular smooth muscle cells. Notch3 deletion is protective in pulmonary hypertension while deleterious in arterial hypertension. Although this latter phenotype was attributed to renal and cardiac alterations, the underlying mechanisms remained unknown. To investigate the role of Notch3 signaling in the cardiac adaptation to hypertension, we used mice with either constitutive Notch3 or smooth muscle cell-specific conditional RBPJκ knockout. At baseline, both genotypes exhibited a cardiac arteriolar rarefaction associated with oxidative stress. In response to angiotensin II-induced hypertension, the heart of Notch3 knockout and SM-RBPJκ knockout mice did not adapt to pressure overload and developed heart failure, which could lead to an early and fatal acute decompensation of heart failure. This cardiac maladaptation was characterized by an absence of media hypertrophy of the media arteries, the transition of smooth muscle cells toward a synthetic phenotype, and an alteration of angiogenic pathways. A subset of mice exhibited an early fatal acute decompensated heart failure, in which the same alterations were observed, although in a more rapid timeframe. Altogether, these observations indicate that Notch3 plays a major role in coronary adaptation to pressure overload. These data also show that the hypertrophy of coronary arterial media on pressure overload is mandatory to initially maintain a normal cardiac function and is regulated by the Notch3/RBPJκ pathway. © 2016 American Heart Association, Inc.

Multisensor System for Isotemporal Measurements to Assess Indoor Climatic Conditions in Poultry Farms

PubMed Central

Bustamante, Eliseo; Guijarro, Enrique; García-Diego, Fernando-Juan; Balasch, Sebastián; Hospitaler, Antonio; Torres, Antonio G.

2012-01-01

The rearing of poultry for meat production (broilers) is an agricultural food industry with high relevance to the economy and development of some countries. Periodic episodes of extreme climatic conditions during the summer season can cause high mortality among birds, resulting in economic losses. In this context, ventilation systems within poultry houses play a critical role to ensure appropriate indoor climatic conditions. The objective of this study was to develop a multisensor system to evaluate the design of the ventilation system in broiler houses. A measurement system equipped with three types of sensors: air velocity, temperature and differential pressure was designed and built. The system consisted in a laptop, a data acquisition card, a multiplexor module and a set of 24 air temperature, 24 air velocity and two differential pressure sensors. The system was able to acquire up to a maximum of 128 signals simultaneously at 5 second intervals. The multisensor system was calibrated under laboratory conditions and it was then tested in field tests. Field tests were conducted in a commercial broiler farm under four different pressure and ventilation scenarios in two sections within the building. The calibration curves obtained under laboratory conditions showed similar regression coefficients among temperature, air velocity and pressure sensors and a high goodness fit (R2 = 0.99) with the reference. Under field test conditions, the multisensor system showed a high number of input signals from different locations with minimum internal delay in acquiring signals. The variation among air velocity sensors was not significant. The developed multisensor system was able to integrate calibrated sensors of temperature, air velocity and differential pressure and operated succesfully under different conditions in a mechanically-ventilated broiler farm. This system can be used to obtain quasi-instantaneous fields of the air velocity and temperature, as well as differential pressure maps to assess the design and functioning of ventilation system and as a verification and validation (V&V) system of Computational Fluid Dynamics (CFD) simulations in poultry farms. PMID:22778611

Adaptability in Crisis Management: The Role of Organizational Structure

DTIC Science & Technology

2013-06-01

individuals to make optimal decisions under constraints of high risk, uncertainty, high workload, and time pressure (see, e.g., Brehmer, 2007 ). There is...et al., 2003; Hallam & Stammers , 1981). For instance, Hallam and Stammers (1981) showed that the impact of variations in task complexity on team...each team member. FIRESCOPE, a commonly used crisis intervention plan developed in California (Office of Emergency Services, 2007 ) is a good

Male hypogonadism and metabolic syndrome.

PubMed

Naifar, M; Rekik, N; Messedi, M; Chaabouni, K; Lahiani, A; Turki, M; Abid, M; Ayedi, F; Jamoussi, K

2015-06-01

The role of androgens in cardiovascular disease is still controversial in men. In this study, we investigated metabolic disorders in Tunisian hypogonadal men compared with healthy controls. Forty hypogonadal men and 80 control subjects were enrolled. Patients with a history of pre-existing panhypopituitarism, thyroid dysfunction or inflammatory disease were excluded. Glycaemia, glycated haemoglobin (HbA1c), high-sensitive C-reactive protein (hsCRP), lipid profile, insulin, testosterone and gonadotrophins were measured. Insulin resistance was assessed by homoeostasis model assessment of insulin resistance (Homa IR). Waist circumference, body mass index and blood pressure were significantly higher in patients compared with controls. Glycemia, HbA1c, fasting serum insulin and Homa IR were significantly increased among hypogonadal men. In univariate analysis, testosterone levels were inversely correlated with body mass index, waist circumference, blood pressure, glycaemia, HbA1C, insulin, Homa IR and hsCRP. In multivariate analysis including all significant variables, initial testosterone level was the only independent risk factor for developing dyslipidaemia. With logistic regression, male hypogonadism was an independent risk factor for MS (P < 0.001). We conclude that low testosterone level plays a central role in the development of metabolic syndrome. Further prospective data are required to establish the causative link. © 2014 Blackwell Verlag GmbH.

Phase transformations in nanograin materials under high pressure and plastic shear: nanoscale mechanisms.

PubMed

Levitas, Valery I; Javanbakht, Mahdi

2014-01-07

There are two main challenges in the discovery of new high pressure phases (HPPs) and transforming this discovery into technologies: finding conditions to synthesize new HPPs and finding ways to reduce the phase transformation (PT) pressure to an economically reasonable level. Based on the results of pressure-shear experiments in the rotational diamond anvil cell (RDAC), superposition of plastic shear on high pressure is a promising way to resolve these problems. However, physical mechanisms behind these phenomena are not yet understood. Here, we elucidate generic mechanisms of coupled nucleation and evolution of dislocation and HPP structures in the nanograin material under pressure and shear utilizing the developed advanced phase field approach (PFA). Dislocations are generated at the grain boundaries and are densely piled up near them, creating a strong concentrator of the stress tensor. Averaged shear stress is essentially larger in the nanograin material due to grain boundary strengthening. This leads to the increase in the local thermodynamic driving force for PT, which allows one to significantly reduce the applied pressure. For all cases, the applied pressure is 3-20 times lower than the PT pressure and 2-12.5 times smaller than the phase equilibrium pressure. Interaction between nuclei leads sometimes to their coalescence and growth of the HPP away from stress concentrators. Plasticity plays a dual role: in addition to creating stress concentrators, it may relax stresses at other concentrators, thus competing with PT. Some ways to optimize the loading parameters have been found that lead to methods for controlling PT. Since such a local stress tensor with high shear stress component cannot be created without plastic deformations, this may lead to new transformation paths and phases, which are hidden during pressure induced PTs.

Quantifying Dynamic Changes in Plantar Pressure Gradient in Diabetics with Peripheral Neuropathy.

PubMed

Lung, Chi-Wen; Hsiao-Wecksler, Elizabeth T; Burns, Stephanie; Lin, Fang; Jan, Yih-Kuen

2016-01-01

Diabetic foot ulcers remain one of the most serious complications of diabetes. Peak plantar pressure (PPP) and peak pressure gradient (PPG) during walking have been shown to be associated with the development of diabetic foot ulcers. To gain further insight into the mechanical etiology of diabetic foot ulcers, examination of the pressure gradient angle (PGA) has been recently proposed. The PGA quantifies directional variation or orientation of the pressure gradient during walking and provides a measure of whether pressure gradient patterns are concentrated or dispersed along the plantar surface. We hypothesized that diabetics at risk of foot ulceration would have smaller PGA in key plantar regions, suggesting less movement of the pressure gradient over time. A total of 27 participants were studied, including 19 diabetics with peripheral neuropathy and 8 non-diabetic control subjects. A foot pressure measurement system was used to measure plantar pressures during walking. PPP, PPG, and PGA were calculated for four foot regions - first toe (T1), first metatarsal head (M1), second metatarsal head (M2), and heel (HL). Consistent with prior studies, PPP and PPG were significantly larger in the diabetic group compared with non-diabetic controls in the T1 and M1 regions, but not M2 or HL. For example, PPP was 165% (P = 0.02) and PPG was 214% (P < 0.001) larger in T1. PGA was found to be significantly smaller in the diabetic group in T1 (46%, P = 0.04), suggesting a more concentrated pressure gradient pattern under the toe. The proposed PGA may improve our understanding of the role of pressure gradient on the risk of diabetic foot ulcers.

Influence of xanthan gum on the structural characteristics of myofibrillar proteins treated by high pressure.

PubMed

Villamonte, Gina; Jury, Vanessa; Jung, Stéphanie; de Lamballerie, Marie

2015-03-01

The effects of xanthan gum on the structural modifications of myofibrillar proteins (0.3 M NaCl, pH 6) induced by high pressure (200, 400, and 600 MPa, 6 min) were investigated. The changes in the secondary and tertiary structures of myofibrillar proteins were analyzed by circular dichroism. The protein denaturation was also evaluated by differential scanning calorimetry. Likewise, the protein surface hydrophobicity and the solubility of myofibrillar proteins were measured. High pressure (600 MPa) induced the loss of α-helix structures and an increase of β-sheet structures. However, the presence of xanthan gum hindered the former mechanism of protein denaturation by high pressure. In fact, changes in the secondary (600 MPa) and the tertiary structure fingerprint of high-pressure-treated myofibrillar proteins (400 to 600 MPa) were observed in the presence of xanthan gum. These modifications were confirmed by the thermal analysis, the thermal transitions of high-pressure (400 to 600 MPa)-treated myofibrillar proteins were modified in systems containing xanthan gum. As consequence, the high-pressure-treated myofibrillar proteins with xanthan gum showed increased solubility from 400 MPa, in contrast to high-pressure treatment (600 MPa) without xanthan gum. Moreover, the surface hydrophobicity of high-pressure-treated myofibrillar proteins was enhanced in the presence of xanthan gum. These effects could be due to the unfolding of myofibrillar proteins at high-pressure levels, which exposed sites that most likely interacted with the anionic polysaccharide. This study suggests that the role of food additives could be considered for the development of meat products produced by high-pressure processing. © 2015 Institute of Food Technologists®

What support do health visitor mentors need?

PubMed

Morton, Sarah

2013-08-01

This paper seeks to explore and understand the role of health visitor mentors undertaking a mentoring responsibility for specialist community public health nurses. During the unprecedented round of health visitor training, responsibility for the direct management of this role has been devolved from practice teachers to mentors. A qualitative approach using a purposive sample of eight participants and a semi-structured interview was the chosen method. Simple qualitative analysis was undertaken allowing data to be compared and themes identified. The overarching theme within this study was 'powerlessness'; mentors felt they had no say in adopting this role which was imposed upon them. Sub-themes included 'preparedness' relating to their perceived lack of appropriate training, and 'emotional support', which identified inadequate support from managers, while good levels of support were experienced by most mentors from their colleagues. Finally, 'compromising' related to difficulties associated with managing client care, student education and family responsibilities, achieved through prioritising and working overtime. In conclusion, the paper suggests that mentors need further support that acknowledges the pressure of the dual role, and standards for professional development of mentors need to be developed.

Effects Of Bedrock Shape And Hillslope Gradient On The Pore-Water Pressure Development: Implication For Slope Stability

NASA Astrophysics Data System (ADS)

Lanni, Cristiano; McDonnell, Jeff

2010-05-01

Shallow Landslides are one of the most important causes of loss of human life and socio-economic damage related to the hydro-geological risk issues. The danger of these phenomena is related to their speed of development, the diffculty of foreseeing their location, and the high density of individual phenomena, whose downhill trajectories have a relevant probability of interfering with urbanized areas. Research activity on precipitation-induced landslides has focused mainly on developing predictive understanding of where and when landslides are likely to occur. Nevertheless, some major aspects that may be related to activation of landslides have been poorly investigated. For instance, landslide susceptibility zones are generally predicted assuming constant thickness of soil over an impervious bedrock layer. Nevertheless, recent studies showed subsurface topography could be a first order control for subsurface water-flow dynamics, because of the effects of its own irregular shape. Tromp-van Meerveld and McDonnell (2006) argued that connectivity of patches of transient saturation were a necessary prerequisite for exceeding the rainfall threshold necessary to drive lateral flow. Connectivity - "how the hillslope architecture controls the filling and spilling of isolated patches of saturation" (Hopp and McDonnell, 2009) - appears to be a possible unifying concept and theoretical platform for moving hillslope and watershed hydrology forward. Connectivity could also have important implications on triggering of shallow landslides, because the particular shape of bedrock may limit the water-flow downhill. Here we present a number of virtual numerical experiments performed to investigate the role of bedrock shape and hillslope gradient on pore-water pressure development. On this purpose, our test is represented by the subsurface topography of the Panola Experiment Hillslope (PEH). That is because scientific literature on PEH provides substantial documentation about the role of bedrock layer on subsurface water-flow dynamics. We also exploit the concept of Downslope Index (DWI) (Hjerdt et al., 2004) and Upslope Contributing Area (UCA) as indicators of the areas more susceptible to landslide. The results indicate that bedrock shape influences the max pore-water pressure, even with different hillslope gradients; meanwhile, hillslope gradient affects the persistence-time of the max pore-water pressure. Moreover, results suggest DWI as an useful index to improve the capability of the very-used SHALSTAB model to assess for landslide susceptibility areas.

Hypertension, Diabetes Type II, and Their Association: Role of Arterial Stiffness.

PubMed

Smulyan, Harold; Lieber, Ari; Safar, Michel E

2016-01-01

In patients with both hypertension and type II diabetes, the systolic blood pressure (SBP) increases linearly with age, while that of diastolic blood pressure (DBP) declines curvilinearly as early as age 45, all suggesting the development of increased arterial stiffness. Increased stiffness is an important, independent, and significant risk predictor in subjects with hypertension and diabetes. In patients with both diseases, stiffness assessed at the same mean arterial pressure (MAP) was significantly higher in diabetic patients. Arterial stiffness is related to age, heart rate (HR), and MAP, but in diabetic patients, it also related to diabetes duration and insulin treatment (IT). In the metabolic syndrome (MetSyn), diabetes also acts on the small arteries through capillary rarefaction to reduce the effective length of the arterial tree, increases the reflected pulse wave and thus the pulse pressure (PP). These studies indicate that diabetes and hypertension additively contribute to increased pulsatility and suggest that any means to reduce stiffness would be beneficial in these conditions. © American Journal of Hypertension, Ltd 2015. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Intra-articular pressures and joint mechanics: should we pay attention to effusion in knee osteoarthritis?

PubMed

Rutherford, Derek James

2014-09-01

What factors play a role to ensure a knee joint does what it should given the demands of moving through the physical environment? This paper aims to probe the hypothesis that intra-articular joint pressures, once a topic of interest, have been left aside in contemporary frameworks in which we now view knee joint function. The focus on ligamentous deficiencies and the chondrocentric view of osteoarthritis, while important, have left little attention to the consideration of other factors that can impair joint function across the lifespan. Dynamic knee stability is required during every step we take. While there is much known about the role that passive structures and muscular activation play in maintaining a healthy knee joint, this framework does not account for the role that intra-articular joint pressures may have in providing joint stability during motion and how these factors interact. Joint injuries invariably result in some form of intra-articular fluid accumulation. Ultimately, it may be how the knee mechanically responds to this fluid, of which pressure plays a significant role that provides the mechanisms for continued function. Do joint pressures provide an important foundation for maintaining knee function? This hypothesis is unique and argues that we are missing an important piece of the puzzle when attempting to understand implications that joint injury and disease have for joint function. Copyright © 2014 Elsevier Ltd. All rights reserved.

Protective Roles of Interferon-γ in Cardiac Hypertrophy Induced by Sustained Pressure Overload.

PubMed

Kimura, Akihiko; Ishida, Yuko; Furuta, Machi; Nosaka, Mizuho; Kuninaka, Yumi; Taruya, Akira; Mukaida, Naofumi; Kondo, Toshikazu

2018-03-19

A clear understanding of the molecular mechanisms underlying hemodynamic stress-initiated cardiac hypertrophy is important for preventing heart failure. Interferon-γ (IFN-γ) has been suggested to play crucial roles in various diseases other than immunological disorders by modulating the expression of myriad genes. However, the involvement of IFN-γ in the pathogenesis of cardiac hypertrophy still remains unclear. In order to elucidate the roles of IFN-γ in pressure overload-induced cardiac pathology, we subjected Balb/c wild-type (WT) or IFN-γ-deficient ( Ifng -/- ) mice to transverse aortic constriction (TAC). Three weeks after TAC, Ifng -/- mice developed more severe cardiac hypertrophy, fibrosis, and dysfunction than WT mice. Bone marrow-derived immune cells including macrophages were a source of IFN-γ in hearts after TAC. The activation of PI3K/Akt signaling, a key signaling pathway in compensatory hypertrophy, was detected 3 days after TAC in the left ventricles of WT mice and was markedly attenuated in Ifng -/- mice. The administration of a neutralizing anti-IFN-γ antibody abrogated PI3K/Akt signal activation in WT mice during compensatory hypertrophy, while that of IFN-γ activated PI3K/Akt signaling in Ifng -/- mice. TAC also induced the phosphorylation of Stat5, but not Stat1 in the left ventricles of WT mice 3 days after TAC. Furthermore, IFN-γ induced Stat5 and Akt phosphorylation in rat cardiomyocytes cultured under stretch conditions. A Stat5 inhibitor significantly suppressed PI3K/Akt signaling activation in the left ventricles of WT mice, and aggravated pressure overload-induced cardiac hypertrophy. The IFN-γ/Stat5 axis may be protective against persistent pressure overload-induced cardiac hypertrophy by activating the PI3K/Akt pathway. © 2018 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.

Preferences for a patient-centered role orientation: association with patient-information-seeking behavior and clinical markers of health.

PubMed

Baldwin, Austin S; Cvengros, Jamie A; Christensen, Alan J; Ishani, Areef; Kaboli, Peter J

2008-02-01

Few data exist examining how patients' preferred role orientation (patient-centered or provider-centered) is associated with "patient-centered" behavior and clinical markers of health. The purpose of the study is to investigate how patients' preferred role orientation is associated with information-seeking behavior and clinical markers of health in a chronically ill population. Participants were 189 hypertensive patients, at two VA Medical Centers and four community-based clinics, who completed measures of preferred role orientation and medication information seeking. Lab values of patients' blood pressure, LDL cholesterol, and glycosylated hemoglobin A1c were used as clinical markers. Preference for a patient-centered role was associated with seeking medication information from various sources (e.g., the internet [OR = 1.14, 95% CI = 1.05-1.23]) and with the number of sources from which patients obtained information (beta = .21, p = 0.005). However, patient-centered preferences were also associated with higher systolic blood pressure (beta = 0.16, p = 0.04), higher diastolic blood pressure (beta = .15, p = 0.04), and higher LDL cholesterol (beta = 0.17, p = 0.04). There was no association with glycosylated hemoglobin A1c (beta = -0.10, p = 0.36). Patients who preferred a patient-centered role engaged in behavior consistent with their preferences, but had higher blood pressure and less favorable lipid levels. These findings are discussed in terms of the nature and treatment of certain chronic conditions that may explain why a patient-centered role orientation is associated with a less favorable clinical profile in some contexts.

Attitudes of surgical nurses towards pressure ulcer prevention.

PubMed

Ünver, Seher; Fındık, Ümmü Yıldız; Özkan, Zeynep Kızılcık; Sürücü, Çağla

2017-11-01

Nurses play the key role in prevention of pressure ulcers, and negative attitudes of them may affect preventive care strategies. This research aimed to identify surgical nurses' attitudes towards pressure ulcer prevention. A descriptive and cross-sectional study design was used to collect data between March 31-May 16, 2016 on 101 voluntary nurses (66.01% of all nurses) working in surgical units of a university hospital in Turkey. "Attitude towards Pressure Ulcer Prevention Instrument" and "Nurse Information Form" were used to investigate nurses' attitude toward preventing pressure ulcer. Descriptive statistics, Mann-Whitney U test, independent samples t-test, Pearson's chi-squared, and correlation tests were used to analyse the data. The mean age of nurses' was 32.0 ± 6.3 years and, the average duration of clinical experience was 72.3 ± 61 months. A total of 54.5% were working in surgical wards and, 40.6% gained additional education about pressure ulcer care. The mean total attitude score was found to be 80.5% (41.8 ± 4.8). Previous education significantly affected the total attitude score of nurses (p < 0.05). The total scale score showed that surgical nurses had a positive attitude towards pressure ulcer prevention and nurses who had previous education about pressure ulcer care has higher attitude score than who had not. It is recommended that effective in-service education programs be developed at hospitals or that nurses be required to attend courses to help them to improve their pressure ulcer care. Copyright © 2017. Published by Elsevier Ltd.

Circular dichroism and site-directed spin labeling reveal structural and dynamical features of high-pressure states of myoglobin

PubMed Central

Lerch, Michael T.; Horwitz, Joseph; McCoy, John; Hubbell, Wayne L.

2013-01-01

Excited states of proteins may play important roles in function, yet are difficult to study spectroscopically because of their sparse population. High hydrostatic pressure increases the equilibrium population of excited states, enabling their characterization [Akasaka K (2003) Biochemistry 42:10875–85]. High-pressure site-directed spin-labeling EPR (SDSL-EPR) was developed recently to map the site-specific structure and dynamics of excited states populated by pressure. To monitor global secondary structure content by circular dichroism (CD) at high pressure, a modified optical cell using a custom MgF2 window with a reduced aperture is introduced. Here, a combination of SDSL-EPR and CD is used to map reversible structural transitions in holomyoglobin and apomyoglobin (apoMb) as a function of applied pressure up to 2 kbar. CD shows that the high-pressure excited state of apoMb at pH 6 has helical content identical to that of native apoMb, but reversible changes reflecting the appearance of a conformational ensemble are observed by SDSL-EPR, suggesting a helical topology that fluctuates slowly on the EPR time scale. Although the high-pressure state of apoMb at pH 6 has been referred to as a molten globule, the data presented here reveal significant differences from the well-characterized pH 4.1 molten globule of apoMb. Pressure-populated states of both holomyoglobin and apoMb at pH 4.1 have significantly less helical structure, and for the latter, that may correspond to a transient folding intermediate. PMID:24248390

Active Defending and Passive Bystanding Behavior in Bullying: The Role of Personal Characteristics and Perceived Peer Pressure

ERIC Educational Resources Information Center

Pozzoli, Tiziana; Gini, Gianluca

2010-01-01

This study examined the role of pro-victim attitudes, personal responsibility, coping responses to observations of bullying, and perceived peer normative pressure in explaining defending the victim and passive bystanding behavior in bullying. A total of 462 Italian early adolescents (mean age = 13.4 years, SD = 9 months) participated in the study.…

How Work Affects Divorce: The Mediating Role of Financial and Time Pressures

ERIC Educational Resources Information Center

Poortman, Anne-Rigt

2005-01-01

This study examines whether the financial and time pressures associated with spouses' working lives play a role in the relation between work and divorce during the first years of marriage. Using retrospective data from the Netherlands, the results show that divorce is more likely when the husband works on average fewer hours and the wife more…

The role of adenosine in preconditioning by brief pressure overload in rats.

PubMed

Huang, Cheng-Hsiung; Tsai, Shen-Kou; Chiang, Shu-Chiung; Lai, Chang-Chi; Weng, Zen-Chung

2015-08-01

Brief pressure overload of the left ventricle reduced myocardial infarct (MI) size in rabbits has been previously reported. Its effects in other species are not known. This study investigates effects of pressure overload and the role of adenosine in rats in this study. MI was induced by 40-minute occlusion of the left anterior descending coronary artery followed by 3-hour reperfusion. MI size was determined by triphenyl tetrazolium chloride staining. Brief pressure overload was induced by two 10-minute episodes of partial snaring of the ascending aorta. Systolic left ventricular pressure was raised 50% above the baseline value. Ischemic preconditioning was elicited by two 10-minute coronary artery occlusions. The MI size (mean ± standard deviation), expressed as percentage of area at risk, was significantly reduced in the pressure overload group as well as in the ischemic preconditioning group (17.4 ± 3.0% and 18.2 ± 1.5% vs. 26.6 ± 2.4% in the control group, p < 0.001). Pretreatment with 8-(p-sulfophenyl)-theophylline (SPT), an inhibitor of adenosine receptors, did not significantly limit the protection by pressure overload and ischemic preconditioning (18.3 ± 1.5% and 18.2 ± 2.0%, respectively, p < 0.001). SPT itself did not affect the extent of infarct (25.4 ± 2.0%). The hemodynamics, area at risk and mortality were not significantly different among all groups of animals. Brief pressure overload of the left ventricle preconditioned rat myocardium against infarction. Because SPT did not significantly alter MI size reduction, our results did not support a role of adenosine in preconditioning by pressure overload in rats. Copyright © 2013. Published by Elsevier B.V.

A linear acoustic model for intake wave dynamics in IC engines

NASA Astrophysics Data System (ADS)

Harrison, M. F.; Stanev, P. T.

2004-01-01

In this paper, a linear acoustic model is described that has proven useful in obtaining a better understanding of the nature of acoustic wave dynamics in the intake system of an internal combustion (IC) engine. The model described has been developed alongside a set of measurements made on a Ricardo E6 single cylinder research engine. The simplified linear acoustic model reported here produces a calculation of the pressure time-history in the port of an IC engine that agrees fairly well with measured data obtained on the engine fitted with a simple intake system. The model has proved useful in identifying the role of pipe resonance in the intake process and has led to the development of a simple hypothesis to explain the structure of the intake pressure time history: the early stages of the intake process are governed by the instantaneous values of the piston velocity and the open area under the valve. Thereafter, resonant wave action dominates the process. The depth of the early depression caused by the moving piston governs the intensity of the wave action that follows. A pressure ratio across the valve that is favourable to inflow is maintained and maximized when the open period of the valve is such to allow at least, but no more than, one complete oscillation of the pressure at its resonant frequency to occur while the valve is open.

An electrothermal plasma model considering polyethylene and copper ablation based on ignition experiment

NASA Astrophysics Data System (ADS)

Zhang, Jiangbo; Li, Xingwen; Hang, Yuhua; Yang, Weihong

2018-06-01

In order to study the characteristics of electrothermal plasma interaction with energetic materials, especially the ignition ability, a novel model considering polyethylene and copper ablation is developed, and an ignition experiment system is set up. The parameters of the plasma and the surface conditions of the energetic materials are measured in the testing. The results show the measured first peak pressure to be ~2.2 MPa, the second peak pressure to be ~3.9 MPa, and the visible flame velocity to be ~2000 m s‑1. Circular pits of the order of microns and nanometers in size are observed on the surface of the energetic materials. Further, the parameters of the plasma, including static pressure, total pressure, density, temperature, velocity, copper concentration and PE concentration, are calculated and analyzed by the established model, under discharge currents of 9 kA. The simulation is similar to those of experimental results. A shock wave is observed in the experiment and is presented in the calculations; it plays an important role in the performance of the plasma in the nozzle region, where the parameters of the plasma variation trends are very complex. With the aim of obtaining the overall performance of the plasma, the coupling characteristics of multiple parameters must be taken into account, in accordance with the developed electrothermal plasma model.

Distinct Roles of Velvet Complex in the Development, Stress Tolerance, and Secondary Metabolism in Pestalotiopsis microspora, a Taxol Producer

PubMed Central

Akhberdi, Oren; Zhang, Qian; Wang, Dan; Wang, Haichuan; Hao, Xiaoran; Liu, Yanjie; Wei, Dongsheng; Zhu, Xudong

2018-01-01

The velvet family proteins have been shown to play critical roles in fungal secondary metabolism and development. However, variations of the roles have been observed in different fungi. We report here the observation on the role of three velvet complex components VeA, VelB, and LaeA in Pestalotiopsis microspora, a formerly reported taxol-producing fungus. Deletion of individual members led to the retardation of vegetative growth and sporulation and pigmentation, suggesting critical roles in these processes. The mutant strain △velB appeared hypersensitive to osmotic stress and the dye Congo red, whereas △veA and △laeA were little affected by the pressures, suggesting only velB was required for the integrity of the cell wall. Importantly, we found that the genes played distinct roles in the biosynthesis of secondary metabolites in P. microspora. For instance, the production of pestalotiollide B, a previously characterized polyketide, required velB and laeA. In contrast, the veA gene appeared to inhibit the pestalotiollide B (PB) role in its biosynthesis. This study suggests that the three components of the velvet complex are important global regulators, but with distinct roles in hyphal growth, asexual production, and secondary metabolism in P. microspora. This work provides information for further understanding the biosynthesis of secondary metabolism in the fungus. PMID:29538316

Distinct Roles of Velvet Complex in the Development, Stress Tolerance, and Secondary Metabolism in Pestalotiopsis microspora, a Taxol Producer.

PubMed

Akhberdi, Oren; Zhang, Qian; Wang, Dan; Wang, Haichuan; Hao, Xiaoran; Liu, Yanjie; Wei, Dongsheng; Zhu, Xudong

2018-03-14

The velvet family proteins have been shown to play critical roles in fungal secondary metabolism and development. However, variations of the roles have been observed in different fungi. We report here the observation on the role of three velvet complex components VeA, VelB, and LaeA in Pestalotiopsis microspora , a formerly reported taxol-producing fungus. Deletion of individual members led to the retardation of vegetative growth and sporulation and pigmentation, suggesting critical roles in these processes. The mutant strain △velB appeared hypersensitive to osmotic stress and the dye Congo red, whereas △veA and △laeA were little affected by the pressures, suggesting only velB was required for the integrity of the cell wall. Importantly, we found that the genes played distinct roles in the biosynthesis of secondary metabolites in P. microspora . For instance, the production of pestalotiollide B, a previously characterized polyketide, required velB and laeA . In contrast, the veA gene appeared to inhibit the pestalotiollide B (PB) role in its biosynthesis. This study suggests that the three components of the velvet complex are important global regulators, but with distinct roles in hyphal growth, asexual production, and secondary metabolism in P. microspora . This work provides information for further understanding the biosynthesis of secondary metabolism in the fungus.

A controlled variation scheme for convection treatment in pressure-based algorithm

NASA Technical Reports Server (NTRS)

Shyy, Wei; Thakur, Siddharth; Tucker, Kevin

1993-01-01

Convection effect and source terms are two primary sources of difficulties in computing turbulent reacting flows typically encountered in propulsion devices. The present work intends to elucidate the individual as well as the collective roles of convection and source terms in the fluid flow equations, and to devise appropriate treatments and implementations to improve our current capability of predicting such flows. A controlled variation scheme (CVS) has been under development in the context of a pressure-based algorithm, which has the characteristics of adaptively regulating the amount of numerical diffusivity, relative to central difference scheme, according to the variation in local flow field. Both the basic concepts and a pragmatic assessment will be presented to highlight the status of this work.

Inclusion of pressure and flow in a new 3D MHD equilibrium code

NASA Astrophysics Data System (ADS)

Raburn, Daniel; Fukuyama, Atsushi

2012-10-01

Flow and nonsymmetric effects can play a large role in plasma equilibria and energy confinement. A concept for such a 3D equilibrium code was developed and presented in 2011. The code is called the Kyoto ITerative Equilibrium Solver (KITES) [1], and the concept is based largely on the PIES code [2]. More recently, the work-in-progress KITES code was used to calculate force-free equilibria. Here, progress and results on the inclusion of pressure and flow in the code are presented. [4pt] [1] Daniel Raburn and Atsushi Fukuyama, Plasma and Fusion Research: Regular Articles, 7:240381 (2012).[0pt] [2] H. S. Greenside, A. H. Reiman, and A. Salas, J. Comput. Phys, 81(1):102-136 (1989).

Lowering of blood pressure by chronic suppression of central sympathetic outflow: insight from prolonged baroreflex activation

PubMed Central

Iliescu, Radu

2012-01-01

Device-based therapy for resistant hypertension by electrical activation of the carotid baroreflex is currently undergoing active clinical investigation, and initial findings from clinical trials have been published. The purpose of this mini-review is to summarize the experimental studies that have provided a conceptual understanding of the mechanisms that account for the long-term lowering of arterial pressure with baroreflex activation. The well established mechanisms mediating the role of the baroreflex in short-term regulation of arterial pressure by rapid changes in peripheral resistance and cardiac function are often extended to long-term pressure control, and the more sluggish actions of the baroreflex on renal excretory function are often not taken into consideration. However, because clinical, experimental, and theoretical evidence indicates that the kidneys play a dominant role in long-term control of arterial pressure, this review focuses on the mechanisms that link baroreflex-mediated reductions in central sympathetic outflow with increases in renal excretory function that lead to sustained reductions in arterial pressure. PMID:22797307

Protein quality control in protection against systolic overload cardiomyopathy: the long term role of small heat shock proteins

PubMed Central

Kumarapeli, Asangi R K; Horak, Kathleen; Wang, Xuejun

2010-01-01

Molecular chaperones represent the first line of defense of intracellular protein quality control. As a major constituent of molecular chaperones, heat shock proteins (HSP) are known to confer cardiomyocyte short-term protection against various insults and injuries. Previously, we reported that the small HSP αB-crystallin (CryAB) attenuates cardiac hypertrophic response in mice subjected to 2 weeks of severe pressure overload. However, the long-term role of small HSPs in cardiac hypertrophy and failure has rarely been studied. The present study investigates the cardiac responses to chronic severe pressure overload in CryAB/HSPB2 germ line ablated (KO) and cardiac-specific CryAB overexpressingtransgenic (TG) mice. Pressure overload was induced by transverse aortic constriction in KO, TG, and non-transgenic wild type (NTG) control mice and 10 weeks later molecular, cellular, and whole organ level hypertrophic responses were analyzed. As we previously described, CryAB/HSPB2 KO mice showed abnormal baseline cardiac physiology that worsened into a restrictive cardiomyopathic phenotype with aging. Severe pressure overload in these mice led to rapid deterioration of heart function and development of congestive cardiac failure. Contrary to their short term protective phenotype, CryAB TG mice showed no significant effects on cardiac hypertrophic responses and very modest improvement of hemodynamics during chronic systolic overload. These findings indicate that small HSPs CryAB and/or HSPB2 are essential to maintain cardiac structure and function but overex-pression of CryAB is not sufficient to confer a sustained protection against chronic systolic overload. PMID:20733949

Protein quality control in protection against systolic overload cardiomyopathy: the long term role of small heat shock proteins.

PubMed

Kumarapeli, Asangi R K; Horak, Kathleen; Wang, Xuejun

2010-07-21

Molecular chaperones represent the first line of defense of intracellular protein quality control. As a major constituent of molecular chaperones, heat shock proteins (HSP) are known to confer cardiomyocyte short-term protection against various insults and injuries. Previously, we reported that the small HSP alphaB-crystallin (CryAB) attenuates cardiac hypertrophic response in mice subjected to 2 weeks of severe pressure overload. However, the long-term role of small HSPs in cardiac hypertrophy and failure has rarely been studied. The present study investigates the cardiac responses to chronic severe pressure overload in CryAB/HSPB2 germ line ablated (KO) and cardiac-specific CryAB overexpressingtransgenic (TG) mice. Pressure overload was induced by transverse aortic constriction in KO, TG, and non-transgenic wild type (NTG) control mice and 10 weeks later molecular, cellular, and whole organ level hypertrophic responses were analyzed. As we previously described, CryAB/HSPB2 KO mice showed abnormal baseline cardiac physiology that worsened into a restrictive cardiomyopathic phenotype with aging. Severe pressure overload in these mice led to rapid deterioration of heart function and development of congestive cardiac failure. Contrary to their short term protective phenotype, CryAB TG mice showed no significant effects on cardiac hypertrophic responses and very modest improvement of hemodynamics during chronic systolic overload. These findings indicate that small HSPs CryAB and/or HSPB2 are essential to maintain cardiac structure and function but overex-pression of CryAB is not sufficient to confer a sustained protection against chronic systolic overload.

Double-Sided Laser Heating in Radial Diffraction Geometry for Diamond Anvil Cell Deformation Experiments at Simultaneous High Pressures and Temperatures

NASA Astrophysics Data System (ADS)

Miyagi, L. M.; Kunz, M.; Couper, S.; Lin, F.; Yan, J.; Doran, A.; MacDowell, A. A.

2017-12-01

The rheology of rocks and minerals in the Earth's deep interior plays a primary role in controlling large scale geodynamic processes such as mantle convection and slab subduction. Plastic deformation resulting from these processes can lead to texture development and associated seismic anisotropy. If a detailed understanding of the link between deformation and seismic anisotropy is established, observations of seismic anisotropy can be used to understand the dynamic state in the deep Earth. However, performing deformation experiments at lower mantle pressure and temperature conditions are extremely challenging. Thus most deformation studies have been performed either at room temperature and high pressure or at reduced pressures and high temperature. Only a few extraordinary efforts have attained pressures and temperatures relevant to lower mantle. Therefore our ability to interpret observations of lower mantle seismic anisotropy in terms of mantle flow models remains limited. In order to expand the pressure and temperature range available for deformation of deep Earth relevant mineral phases, we have developed a laser heating system for in-situ double-sided heating in radial diffraction geometry at beamline 12.2.2 of the Advanced Light Source of Lawrence Berkeley National Laboratory. This allows texture and lattice strain measurements to be recorded at simultaneous high pressures and temperatures in the diamond anvil cell. This new system is integrated into the newly built axial laser heating system to allow for rapid and reliable transitioning between double-sided laser heating in axial and radial geometries. Transitioning to radial geometry is accomplished by redirecting the laser and imaging paths from 0° and 180° to 90° and 270°. To redirect the 90° path, a motorized periscope mirror pair with an objective lens can be inserted into the downstream axial beam path. The 270° redirection is accomplished by removing the upstream axial objective lens and manually installing a small assembly carrying 2 infrared mirrors and an objective lens. Using this system we have performed two pilot studies recording texture and lattice strain development during deformation of FeO up to 1300 K and 45 GPa and bridgmanite up to 1600 K and 80 GPa.

The mechanics of locomotion in the squid Loligo pealei: locomotory function and unsteady hydrodynamics of the jet and intramantle pressure.

PubMed

Anderson, E J; DeMont, M E

2000-09-01

High-speed, high-resolution digital video recordings of swimming squid (Loligo pealei) were acquired. These recordings were used to determine very accurate swimming kinematics, body deformations and mantle cavity volume. The time-varying squid profile was digitized automatically from the acquired swimming sequences. Mantle cavity volume flow rates were determined under the assumption of axisymmetry and the condition of incompressibility. The data were then used to calculate jet velocity, jet thrust and intramantle pressure, including unsteady effects. Because of the accurate measurements of volume flow rate, the standard use of estimated discharge coefficients was avoided. Equations for jet and whole-cycle propulsive efficiency were developed, including a general equation incorporating unsteady effects. Squid were observed to eject up to 94 % of their intramantle working fluid at relatively high swimming speeds. As a result, the standard use of the so-called large-reservoir approximation in the determination of intramantle pressure by the Bernoulli equation leads to significant errors in calculating intramantle pressure from jet velocity and vice versa. The failure of this approximation in squid locomotion also implies that pressure variation throughout the mantle cannot be ignored. In addition, the unsteady terms of the Bernoulli equation and the momentum equation proved to be significant to the determination of intramantle pressure and jet thrust. Equations of propulsive efficiency derived for squid did not resemble Froude efficiency. Instead, they resembled the equation of rocket motor propulsive efficiency. The Froude equation was found to underestimate the propulsive efficiency of the jet period of the squid locomotory cycle and to overestimate whole-cycle propulsive efficiency when compared with efficiencies calculated from equations derived with the squid locomotory apparatus in mind. The equations for squid propulsive efficiency reveal that the refill period of squid plays a greater role, and the jet period a lesser role, in the low whole-cycle efficiencies predicted in squid and similar jet-propelled organisms. These findings offer new perspectives on locomotory hydrodynamics, intramantle pressure measurements and functional morphology with regard to squid and other jet-propelled organisms.

ROHO Dry floatation technology: implications for clinical practice.

PubMed

Stephen-Haynes, Jackie

2009-09-01

This article discusses the aetiology of pressure ulcers, the clinical and financial cost of pressure ulcer prevention and the need for pressure reducing equipment. The role of Dry floatation in pressure ulcer prevention and management is explored. How Dry floatation technology works is discussed and its use within clinical practice is highlighted. The evidence to support Dry floatation is presented.

Postnatal Ablation of Foxm1 from Cardiomyocytes Causes Late Onset Cardiac Hypertrophy and Fibrosis without Exacerbating Pressure Overload-Induced Cardiac Remodeling

PubMed Central

Bolte, Craig; Zhang, Yufang; York, Allen; Kalin, Tanya V.; Schultz, Jo El J.; Molkentin, Jeffery D.; Kalinichenko, Vladimir V.

2012-01-01

Heart disease remains a leading cause of morbidity and mortality in the industrialized world. Hypertrophic cardiomyopathy is the most common genetic cardiovascular disorder and the most common cause of sudden cardiac death. Foxm1 transcription factor (also known as HFH-11B, Trident, Win or MPP2) plays an important role in the pathogenesis of various cancers and is a critical mediator of post-injury repair in multiple organs. Foxm1 has been previously shown to be essential for heart development and proliferation of embryonic cardiomyocytes. However, the role of Foxm1 in postnatal heart development and in cardiac injury has not been evaluated. To delete Foxm1 in postnatal cardiomyocytes, αMHC-Cre/Foxm1fl/fl mice were generated. Surprisingly, αMHC-Cre/Foxm1fl/fl mice exhibited normal cardiomyocyte proliferation at postnatal day seven and had no defects in cardiac structure or function but developed cardiac hypertrophy and fibrosis late in life. The development of cardiomyocyte hypertrophy and cardiac fibrosis in aged Foxm1-deficient mice was associated with reduced expression of Hey2, an important regulator of cardiac homeostasis, and increased expression of genes critical for cardiac remodeling, including MMP9, αSMA, fibronectin and vimentin. We also found that following aortic constriction Foxm1 mRNA and protein were induced in cardiomyocytes. However, Foxm1 deletion did not exacerbate cardiac hypertrophy or fibrosis following chronic pressure overload. Our results demonstrate that Foxm1 regulates genes critical for age-induced cardiomyocyte hypertrophy and cardiac fibrosis. PMID:23144938

Gender-specific association of the plasminogen activator inhibitor-1 4G/5G polymorphism with central arterial blood pressure.

PubMed

Björck, Hanna M; Eriksson, Per; Alehagen, Urban; De Basso, Rachel; Ljungberg, Liza U; Persson, Karin; Dahlström, Ulf; Länne, Toste

2011-07-01

The functional plasminogen activator inhibitor-1 (PAI-1) 4G/5G polymorphism has previously been associated with hypertension. In recent years, central blood pressure, rather than brachial has been argued a better measure of cardiovascular damage and clinical outcome. The aim of this study was to investigate the possible influence of the 4G/5G polymorphism on central arterial blood pressure in a cohort of elderly individuals. We studied 410 individuals, 216 men and 194 women, aged 70-88. Central pressures and pulse waveforms were calculated from the radial artery pressure waveform by the use of the SphygmoCor system and a generalized transfer function. Brachial pressure was recorded using oscillometric technique (Dinamap, Critikon, Tampa, FL). PAI-1 antigen was determined in plasma. The results showed that central pressures were higher in women carrying the PAI-1 4G/4G genotype compared to female carriers of the 5G/5G genotype, (P = 0.025, P = 0.002, and P = 0.002 for central systolic-, diastolic-, and mean arterial pressure, respectively). The association remained after adjustment for potentially confounding factors related to hypertension. No association of the PAI-1 genotype with blood pressure was found in men. Multiple regression analysis revealed an association between PAI-1 genotype and plasma PAI-1 levels (P = 0.048). Our findings show a gender-specific association of the PAI-1 4G/5G polymorphism with central arterial blood pressure. The genotype effect was independent of other risk factors related to hypertension, suggesting that impaired fibrinolytic potential may play an important role in the development of central hypertension in women.

The Role of the Melanocortin System in Metabolic Disease: New Developments and Advances.

PubMed

Hill, Jennifer W; Faulkner, Latrice D

2017-01-01

Obesity is increasing in prevalence across all sectors of society, and with it a constellation of associated ailments including hypertension, type 2 diabetes, and eating disorders. The melanocortin system is a critical neural system underlying the control of body weight and other functions. Deficits in the melanocortin system may promote or exacerbate the comorbidities of obesity. This system has therefore generated great interest as a potential target for treatment of obesity. However, drugs targeting melanocortin receptors are plagued by problematic side effects, including undesirable increases in sympathetic nervous system activity, heart rate, and blood pressure. Circumnavigating this roadblock will require a clearer picture of the precise neural circuits that mediate the functions of melanocortins. Recent, novel experimental approaches have significantly advanced our understanding of these pathways. We here review the latest advances in our understanding of the role of melanocortins in food intake, reward pathways, blood pressure, glucose control, and energy expenditure. The evidence suggests that downstream melanocortin-responsive circuits responsible for different physiological actions do diverge. Ultimately, a more complete understanding of melanocortin pathways and their myriad roles should allow treatments tailored to the mix of metabolic disorders in the individual patient. © 2016 The Author(s) Published by S. Karger AG, Basel.

Theory to predict particle migration and margination in the pressure-driven channel flow of blood

NASA Astrophysics Data System (ADS)

Qi, Qin M.; Shaqfeh, Eric S. G.

2017-09-01

The inhomogeneous concentration distribution of erythrocytes and platelets in microchannel flows particularly in directions normal to the mean flow plays a significant role in hemostasis, drug delivery, and microfluidic applications. In this paper, we develop a coarse-grained theory to predict these distributions in pressure-driven channel flow at zero Reynolds number and compare them to experiments and simulations. We demonstrate that the balance between the deformability-induced lift force and the shear-induced diffusion created by hydrodynamic interactions in the suspension results in both a peak concentration of red blood cells at the channel center and a cell-free or Fahraeus-Lindqvist layer near the walls. On the other hand, the absence of a lift force and the strong red blood cell-platelet interactions result in an excess concentration of platelets in the cell-free layer. We demonstrate a strong role of hematocrit (i.e., erythrocyte volume fraction) in determining the cell-free layer thickness and the degree of platelet margination. We also demonstrate that the capillary number of the erythrocytes, based on the membrane shear modulus, plays a relatively insignificant role in the regimes that we have studied. Our theory serves as a good and simple alternative to large-scale computer simulations of the cross-stream transport processes in these mixtures.

Notch signalling in T cell lymphoblastic leukaemia/lymphoma and other haematological malignancies

PubMed Central

Aster, Jon C.; Blacklow, Stephen C.; Pear, Warren S.

2010-01-01

Notch receptors participate in a highly conserved signalling pathway that regulates normal development and tissue homeostasis in a context- and dose-dependent manner. Deregulated Notch signalling has been implicated in many diseases, but the clearest example of a pathogenic role is found in T cell lymphoblastic leukaemia/lymphoma (T-LL), in which the majority of human and murine tumours have acquired mutations that lead to aberrant increases in Notch1 signalling. Remarkably, it appears that the selective pressure for Notch mutations is virtually unique among cancers to T-LL, presumably reflecting a special context-dependent role for Notch in normal T cell progenitors. Nevertheless, there are some recent reports suggesting that Notch signalling has subtle yet important roles in other forms of hematologic malignancy as well. Here, we review the role of Notch signalling in various blood cancers, focusing on T-LL with an eye toward targeted therapeutics. PMID:20967796

The C-terminus of the long AKAP13 isoform (AKAP-Lbc) is critical for development of compensatory cardiac hypertrophy

PubMed Central

Taglieri, Domenico M.; Johnson, Keven R.; Burmeister, Brian T.; Monasky, Michelle M.; Spindler, Matthew J.; DeSantiago, Jaime; Banach, Kathrin; Conklin, Bruce R.; Carnegie, Graeme K.

2014-01-01

The objective of this study was to determine the role of A-Kinase Anchoring Protein (AKAP)-Lbc in the development of heart failure, by investigating AKAP-Lbc-protein kinase D1 (PKD1) signaling in vivo in cardiac hypertrophy. Using a gene-trap mouse expressing a truncated version of AKAP-Lbc (due to disruption of the endogenous AKAP-Lbc gene), that abolishes PKD1 interaction with AKAP-Lbc (AKAPLbc-ΔPKD), we studied two mouse models of pathological hypertrophy: i) angiotensin (AT-II) and phenylephrine (PE) infusion and ii) transverse aortic constriction (TAC)-induced pressure overload. Our results indicate that AKAP-Lbc-ΔPKD mice exhibit an accelerated progression to cardiac dysfunction in response to AT-II/PE treatment and TAC. AKAP-Lbc-ΔPKD mice display attenuated compensatory cardiac hypertrophy, increased collagen deposition and apoptosis, compared to wild-type (WT) control littermates. Mechanistically, reduced levels of PKD1 activation are observed in AKAP-Lbc-ΔPKD mice compared to WT mice, resulting in diminished phosphorylation of histone deacetylase 5 (HDAC5) and decreased hypertrophic gene expression. This is consistent with a reduced compensatory hypertrophy phenotype leading to progression of heart failure in AKAP-Lbc-ΔPKD mice. Overall, our data demonstrates a critical in vivo role for AKAP-Lbc-PKD1 signaling in the development of compensatory hypertrophy to enhance cardiac performance in response to TAC-induced pressure overload and neurohumoral stimulation by AT-II/PE treatment. PMID:24161911

The C-terminus of the long AKAP13 isoform (AKAP-Lbc) is critical for development of compensatory cardiac hypertrophy.

PubMed

Taglieri, Domenico M; Johnson, Keven R; Burmeister, Brian T; Monasky, Michelle M; Spindler, Matthew J; DeSantiago, Jaime; Banach, Kathrin; Conklin, Bruce R; Carnegie, Graeme K

2014-01-01

The objective of this study was to determine the role of A-Kinase Anchoring Protein (AKAP)-Lbc in the development of heart failure, by investigating AKAP-Lbc-protein kinase D1 (PKD1) signaling in vivo in cardiac hypertrophy. Using a gene-trap mouse expressing a truncated version of AKAP-Lbc (due to disruption of the endogenous AKAP-Lbc gene), that abolishes PKD1 interaction with AKAP-Lbc (AKAP-Lbc-ΔPKD), we studied two mouse models of pathological hypertrophy: i) angiotensin (AT-II) and phenylephrine (PE) infusion and ii) transverse aortic constriction (TAC)-induced pressure overload. Our results indicate that AKAP-Lbc-ΔPKD mice exhibit an accelerated progression to cardiac dysfunction in response to AT-II/PE treatment and TAC. AKAP-Lbc-ΔPKD mice display attenuated compensatory cardiac hypertrophy, increased collagen deposition and apoptosis, compared to wild-type (WT) control littermates. Mechanistically, reduced levels of PKD1 activation are observed in AKAP-Lbc-ΔPKD mice compared to WT mice, resulting in diminished phosphorylation of histone deacetylase 5 (HDAC5) and decreased hypertrophic gene expression. This is consistent with a reduced compensatory hypertrophy phenotype leading to progression of heart failure in AKAP-Lbc-ΔPKD mice. Overall, our data demonstrates a critical in vivo role for AKAP-Lbc-PKD1 signaling in the development of compensatory hypertrophy to enhance cardiac performance in response to TAC-induced pressure overload and neurohumoral stimulation by AT-II/PE treatment. © 2013.

Contribution of ALDH2 polymorphism to alcoholism-associated hypertension.

PubMed

Hu, Nan; Zhang, Yingmei; Nair, Sreejayan; Culver, Bruce W; Ren, Jun

2014-01-01

Chronic alcohol intake is considered as an independent lifestyle factor that may influence the risk of a number of cardiovascular anomalies including hypertension. In healthy adults, binge drinking and chronic alcohol ingestion lead to the onset and development of hypertension although the precise mechanism(s) remains obscure. Although oxidative stress and endothelial injury have been postulated to play a major contributing role to alcoholism-induced hypertension, recent evidence depicted a rather unique role for the genotype of the acetaldehyde-metabolizing enzyme mitochondrial aldehyde dehydrogenase (ALDH2), which is mainly responsible for detoxifying ethanol consumed, in alcoholism-induced elevation of blood pressure. Genetic polymorphism of ALDH2 in human results in altered ethanol pharmacokinetic properties and ethanol metabolism, leading to accumulation of the ethanol metabolite acetaldehyde following alcohol intake. The unfavorable consequence of the ALDH2 variants is believed to be governed by the accumulation of the ethanol metabolite acetaldehyde. Presence of the mutant or inactive ALDH2*2 gene often results in an increased risk of hypertension in human. Such association between blood pressure and ALDH2 enzymatic activity may be affected by the interplay between gene and environment, such as life style and ethnicity. The aim of this mini-review is to summarize the possible contribution of ALDH2 genetic polymorphism in the onset and development of alcoholism-related development of hypertension. Furthermore, the double-edged sword of ALDH2 gene and genetic polymorphism in alcoholism and alcoholic tissue damage and relevant patents will be discussed.

From socially prescribed perfectionism to problematic use of internet communicative services: the mediating roles of perceived social support and the fear of negative evaluation.

PubMed

Casale, Silvia; Fioravanti, Giulia; Flett, Gordon L; Hewitt, Paul L

2014-12-01

The present study developed and tested a model that explains how people who believe that others have unrealistically high standards and exert pressure on them to be perfect (that is, people high in socially prescribed perfectionism) develop a problematic use of internet communicative services (GPIU). Following the perfectionism social disconnection model and previous evidence about the role that the online environment might play in the development of problematic internet use, low reported social support and the fear of negative evaluations in face to face interactions were hypothesized to mediate the association between socially prescribed perfectionism and GPIU. A sample of 465 undergraduate students was recruited (240 F; mean age 21.91+2.23years), and the hypotheses were tested through structural equation modeling separately for men and women. Among men, the association between SPP and GPIU was fully mediated by the fear of being negatively evaluated and the perception of low social support. For women, we found a partially mediated model in which SPP affected GPIU indirectly through the fear of negative evaluations. The presence of a direct effect of SPP on GPIU was also found. Moreover, perceived social support was not found to be a significant mediator among women. The findings suggest that problematic use of internet communicative services might be, at least in part, a defensive response to extreme social evaluation pressures. Copyright © 2014 Elsevier Ltd. All rights reserved.

Protease-activated receptor 2-mediated protection of myocardial ischemia-reperfusion injury: role of transient receptor potential vanilloid receptors

PubMed Central

Zhong, Beihua

2009-01-01

Activation of the protease-activated receptor 2 (PAR2) or the transient receptor potential vanilloid type 1 (TRPV1) channels expressed in cardiac sensory afferents containing calcitonin gene-related peptide (CGRP) and/or substance P (SP) has been proposed to play a protective role in myocardial ischemia-reperfusion (I/R) injury. However, the interaction between PAR2 and TRPV1 is largely unknown. Using gene-targeted TRPV1-null mutant (TRPV1−/−) or wild-type (WT) mice, we test the hypothesis that TRPV1 contributes to PAR2-mediated cardiac protection via increasing the release of CGRP and SP. Immunofluorescence labeling showed that TRPV1 coexpressed with PAR2, PKC-ε, or PKAc in cardiomyocytes, cardiac blood vessels, and perivascular nerves in WT but not TRPV1−/− hearts. WT or TRPV1−/− hearts were Langendorff perfused with the selective PAR2 agonist, SLIGRL, in the presence or absence of various antagonists, followed by 35 min of global ischemia and 40 min of reperfusion (I/R). The recovery rate of coronary flow, the maximum rate of left ventricular pressure development, left ventricular end-diastolic pressure, and left ventricular developed pressure were evaluated after I/R. SLIGRL improved the recovery of hemodynamic parameters, decreased lactate dehydrogenase release, and reduced the infarct size in both WT and TRPV1−/− hearts (P < 0.05). The protection of SLIGRL was significantly surpassed for WT compared with TRPV1−/− hearts (P < 0.05). CGRP8–37, a selective CGRP receptor antagonist, RP67580, a selective neurokinin-1 receptor antagonist, PKC-ε V1–2, a selective PKC-ε inhibitor, or H-89, a selective PKA inhibitor, abolished SLIGRL protection by inhibiting the recovery of the rate of coronary flow, maximum rate of left ventricular pressure development, and left ventricular developed pressure, and increasing left ventricular end-diastolic pressure in WT but not TRPV1−/− hearts. Radioimmunoassay showed that SLIGRL increased the release of CGRP and SP in WT but not TRPV1−/− hearts (P < 0.05), which were prevented by PKC-ε V1–2 and H-89. Thus our data show that PAR2 activation improves cardiac recovery after I/R injury in WT and TRPV1−/− hearts, with a greater effect in the former, suggesting that PAR2-mediated protection is TRPV1 dependent and independent, and that dysfunctional TRPV1 impairs PAR2 action. PAR2 activation of the PKC-ε or PKA pathway stimulates or sensitizes TRPV1 in WT hearts, leading to the release of CGRP and SP that contribute, at least in part, to PAR2-induced cardiac protection against I/R injury. PMID:19812353

Commentary on Skene and Parker: the role of the church in developing the law.

PubMed

Gormally, L

2002-08-01

Skene and Parker are demonstrably mistaken in suggesting that the amicus role of Catholic bishops in three cases has been concerned with "developing" the law. In contrast with Skene and Parker's freestanding conception of legal principle, the Catholic understanding of law's rational moral foundations has permitted Catholic bishops to defend longstanding legal principle as well as defending the integrity of the church's health care and welfare services. It is shown that in the three cases under discussion Catholic bishops were providing needed argument otherwise unavailable to the courts in defence of existing statute. In face of the attempts by pressure groups to bypass the legislature and use the courts to subvert fundamental legal principles, the church is perhaps uniquely capable of continuing to provide to the courts rational defences of those principles.

[Immune system and tumors].

PubMed

Terme, Magali; Tanchot, Corinne

2017-02-01

Despite having been much debated, it is now well established that the immune system plays an essential role in the fight against cancer. In this article, we will highlight the implication of the immune system in the control of tumor growth and describe the major components of the immune system involved in the antitumoral immune response. The immune system, while exerting pressure on tumor cells, also will play a pro-tumoral role by sculpting the immunogenicity of tumors cells as they develop. Finally, we will illustrate the numerous mechanisms of immune suppression that take place within the tumoral microenvironment which allow tumor cells to escape control from the immune system. The increasingly precise knowledge of the brakes to an effective antitumor immune response allows the development of immunotherapy strategies more and more innovating and promising of hope. Copyright © 2016. Published by Elsevier Masson SAS.

The Effectiveness of the Life Skills Program IPSY for the Prevention of Adolescent Tobacco Use: The Mediating Role of Yielding to Peer Pressure

ERIC Educational Resources Information Center

Weichold, Karina; Tomasik, Martin J.; Silbereisen, Rainer K.; Spaeth, Michael

2016-01-01

In this study, the effectiveness of a life skills program to impede tobacco use in early adolescence was scrutinized. The focus was on the mediating role of yielding to peer pressure. The universal school-based life skills program IPSY (Information + Psychosocial Competence = Protection) against adolescent substance use was implemented over 3…

Wetting-dewetting films: the role of structural forces.

PubMed

Nikolov, Alex; Wasan, Darsh

2014-04-01

The liquid wetting and dewetting of solids are ubiquitous phenomena that occur in everyday life. Understanding the nature of these phenomena is beneficial for research and technological applications. However, despite their importance, the phenomena are still not well understood because of the nature of the substrate's surface energy non-ideality and dynamics. This paper illustrates the mechanisms and applications of liquid wetting and dewetting on hydrophilic and hydrophobic substrates. We discuss the classical understanding and application of wetting and film stability criteria based on the Frumkin-Derjaguin disjoining pressure model. The roles of the film critical thickness and capillary pressure on the film instability based on the disjoining pressure isotherm are elucidated, as are the criteria for stable and unstable wet films. We consider the film area in the model for the film stability and the applicable experiments. This paper also addresses the two classic film instability mechanisms for suspended liquid films based on the conditions of the free energy criteria originally proposed by de Vries (nucleation hole formation) and Vrij-Scheludko (capillary waves vs. van der Waals forces) that were later adapted to explain dewetting. We include a discussion of the mechanisms of nanofilm wetting and dewetting on a solid substrate based on nanoparticles' tendency to form a 2D layer and 2D inlayer in the film under the wetting film's surface confinement. We also present our view on the future of wetting-dewetting modeling and its applications in developing emerging technologies. We believe the review and analysis presented here will benefit the current and future understanding of the wetting-dewetting phenomena, as well as aid in the development of novel products and technologies. © 2013.

Modeling the Transition From Predominantly Gas- to Predominantly Aerosol-Phase Products From OH Reactions With the Homologous Series of C10 to C15 n- Alkanes

NASA Astrophysics Data System (ADS)

Jordan, C. E.; Ziemann, P. J.; Griffin, R. J.; Lim, Y. B.; Atkinson, R.; Arey, J.

2006-12-01

Recent laboratory studies have shown significant formation of secondary organic aerosol (SOA) from OH reactions with a homologous series of n-alkanes. SOA mass yields of 56% were observed for pentadecane (C15), while only 0.5% yield was observed from octane (C8, the smallest alkane in the series). A rapid transition in SOA yield is observed from C10 to C13, with SOA yields increasing from 4% to 49%. In standard gas-aerosol partitioning theory, the vapor pressure controls the amount of material that can condense into the particle phase. However, the rapid transition observed here suggests there may also be a shift in the predominant reaction pathways for longer chain alkanes, leading to greater production of lower vapor pressure products. Here we present an investigation of the role of vapor pressure versus the role of shifting branching ratios to test the influence of each of these on SOA mass yields. We have added each of the alkanes in this series to the Caltech Atmospheric Chemistry Mechanism (CACM). This mechanism was developed in part to predict explicitly concentrations of secondary and tertiary semivolatile oxidation products that potentially form SOA. Although it is has been developed to lump similar compounds together for computational efficiency, it is nonetheless easily adapted and ideally suited for a detailed zero-dimensional modeling study of this kind. This gas-phase mechanism is linked to the aerosol partitioning module MPMPO (Model to Predict the Multi- phase Partitioning of Organics). MPMPO is a fully coupled module that allows the simultaneous partitioning of semi-volatile species to both an aqueous and an organic aerosol phase.

Seventh workshop on the role of impurities and defects in silicon device processing

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

NONE

1997-08-01

This workshop is the latest in a series which has looked at technological issues related to the commercial development and success of silicon based photovoltaic (PV) modules. PV modules based on silicon are the most common at present, but face pressure from other technologies in terms of cell performance and cell cost. This workshop addresses a problem which is a factor in the production costs of silicon based PV modules.

Advice from SOF on the Use of SOF for the Next Administration

DTIC Science & Technology

2016-10-01

diversity of the force via greater recruitment of minorities and women , and place an emphasis on their development, mentorship, and retention . Also...expected to have.” Others 5 pointed out that SOF are experts at marrying the lowest and highest levels of technology to produce unique...National Mission Force. Attendees understood the decision to open all SOF roles to women , but were sensitive to potential pressures to lower

F-15A in flight closeup of 10 degree cone experiment

NASA Image and Video Library

1976-02-04

The number two F-15A (Serial #71-0281) was obtained by NASA from the U.S. Air Force in 1976 and was used for more than 25 advanced research projects involving aerodynamics, performance, propulsion control, control integration, instrumentation development, human factors, and flight test techniques. Included in these projects was its role as a testbed to evaluate aerodynamic pressures on Space Shuttle thermal protection tiles at specific altitudes and speeds.

Hydrostatic pressure enhances chondrogenic differentiation of human bone marrow stromal cells in osteochondrogenic medium.

PubMed

Wagner, Diane R; Lindsey, Derek P; Li, Kelvin W; Tummala, Padmaja; Chandran, Sheena E; Smith, R Lane; Longaker, Michael T; Carter, Dennis R; Beaupre, Gary S

2008-05-01

This study demonstrated the chondrogenic effect of hydrostatic pressure on human bone marrow stromal cells (MSCs) cultured in a mixed medium containing osteogenic and chondrogenic factors. MSCs seeded in type I collagen sponges were exposed to 1 MPa of intermittent hydrostatic pressure at a frequency of 1 Hz for 4 h per day for 10 days, or remained in identical culture conditions but without exposure to pressure. Afterwards, we compared the proteoglycan content of loaded and control cell/scaffold constructs with Alcian blue staining. We also used real-time PCR to evaluate the change in mRNA expression of selected genes associated with chondrogenic and osteogenic differentiation (aggrecan, type I collagen, type II collagen, Runx2 (Cbfa-1), Sox9, and TGF-beta1). With the hydrostatic pressure loading regime, proteoglycan staining increased markedly. Correspondingly, the mRNA expression of chondrogenic genes such as aggrecan, type II collagen, and Sox9 increased significantly. We also saw a significant increase in the mRNA expression of type I collagen, but no change in the expression of Runx2 or TGF-beta1 mRNA. This study demonstrated that hydrostatic pressure enhanced differentiation of MSCs in the presence of multipotent differentiation factors in vitro, and suggests the critical role that this loading regime may play during cartilage development and regeneration in vivo.

The role of shoe design on the prediction of free torque at the shoe-surface interface using pressure insole technology.

PubMed

Weaver, Brian Thomas; Fitzsimons, Kathleen; Braman, Jerrod; Haut, Roger

2016-09-01

The goal of the current study was to expand on previous work to validate the use of pressure insole technology in conjunction with linear regression models to predict the free torque at the shoe-surface interface that is generated while wearing different athletic shoes. Three distinctly different shoe designs were utilised. The stiffness of each shoe was determined with a material's testing machine. Six participants wore each shoe that was fitted with an insole pressure measurement device and performed rotation trials on an embedded force plate. A pressure sensor mask was constructed from those sensors having a high linear correlation with free torque values. Linear regression models were developed to predict free torques from these pressure sensor data. The models were able to accurately predict their own free torque well (RMS error 3.72 ± 0.74 Nm), but not that of the other shoes (RMS error 10.43 ± 3.79 Nm). Models performing self-prediction were also able to measure differences in shoe stiffness. The results of the current study showed the need for participant-shoe specific linear regression models to insure high prediction accuracy of free torques from pressure sensor data during isolated internal and external rotations of the body with respect to a planted foot.

The Critical Role of Pulmonary Arterial Compliance in Pulmonary Hypertension

PubMed Central

Prins, Kurt W.; Pritzker, Marc R.; Scandurra, John; Volmers, Karl; Weir, E. Kenneth

2016-01-01

The normal pulmonary circulation is a low-pressure, high-compliance system. Pulmonary arterial compliance decreases in the presence of pulmonary hypertension because of increased extracellular matrix/collagen deposition in the pulmonary arteries. Loss of pulmonary arterial compliance has been consistently shown to be a predictor of increased mortality in patients with pulmonary hypertension, even more so than pulmonary vascular resistance in some studies. Decreased pulmonary arterial compliance causes premature reflection of waves from the distal pulmonary vasculature, leading to increased pulsatile right ventricular afterload and eventually right ventricular failure. Evidence suggests that decreased pulmonary arterial compliance is a cause rather than a consequence of distal small vessel proliferative vasculopathy. Pulmonary arterial compliance decreases early in the disease process even when pulmonary artery pressure and pulmonary vascular resistance are normal, potentially enabling early diagnosis of pulmonary vascular disease, especially in high-risk populations. With the recognition of the prognostic importance of pulmonary arterial compliance, its impact on right ventricular function, and its contributory role in the development and progression of distal small-vessel proliferative vasculopathy, pulmonary arterial compliance is an attractive target for the treatment of pulmonary hypertension. PMID:26848601

The role of telemedicine in obstructive sleep apnea management.

PubMed

Lugo, Vera; Villanueva, Jair Asir; Garmendia, Onintza; Montserrat, Josep M

2017-09-01

Obstructive sleep apnea (OSA) is a common disease that leads in notorious symptoms and comorbidities. Although general measures are important, continuous positive airway pressure (CPAP) is the best treatment option. However, compliance can be suboptimal and telemedicine may play a role to improve it. Areas covered: Review authors searched EMBASE, PubMed and Cochrane data bases using the following keywords: continuous positive airway pressure, Obstructive sleep apnea, telemedicine, respiratory telemedicine, information and communication technology. Papers published between 2000 and 2016 in English language were considered. Expert commentary: To improve OSA management, there is a pressing need to develop new cost-effective strategies, particularly those related to OSA treatment, from measures such as lifestyle changes to CPAP use. Two broad strategies should be implemented: 1) adequate pre-, peri-, and post-titration measures to ensure correct diagnosis, adequate training, and appropriate support during follow up; and 2) the use of technological advances including both the optimization of CPAP devices and the use of telemedicine, specially focused on the first days or weeks of treatment. Telemedicine can help with these processes, especially when it is personalized to the needs of each patient group.

[Pressure sores in geriatric medicine: the role of nutrition].

PubMed

Fontaine, Juliette; Raynaud-Simon, Agathe

2008-01-01

Malnutrition is frequent in geriatric patients: it affects 30 to 60% of elderly residents of institutions and 30 to 70% of patients admitted for short-term hospitalization. Malnutrition is a risk factor for developing pressure sores, and patients with them are more often and more severely malnourished than patients without them. In elderly subjects, multiple and interlinked factors may trigger or aggravate malnutrition; they may be physical, psychological or social and may be worsened by drugs and some diets. Malnutrition has been recognized as a risk factor for the onset and perpetuation of pressure sores. Of the dietary factors, protein intake seems most important. A low body mass index (BMI), low serum albumin, and weight loss are associated with an increased risk of pressure sores. A physician observing pressure sores must conduct a nutritional assessment, using clinical and laboratory screening tools. The criteria for malnutrition in elderly subjects are weight loss > or =5% in 3 months or > or =10% in 6 months, BMI<21 kg/m(2), serum albumin<35 g/L or a MNA (Mini Nutritional Assessment) score<17. Any one of these criteria is a sufficient basis for a diagnosis of malnutrition. Nutritional management is part of the prevention and treatment of pressure sores in geriatric medicine. It must be adapted for each patient. The recommended calorie intake in malnourished patients at risk of or with pressure sores is 30-40 kcal/kg/d, with 1.2-1.5 g of proteins/kg/d.

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 patients at risk. © 2016 John Wiley & Sons Ltd.

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.

Delayed extubation to nasal continuous positive airway pressure in the immature baboon model of bronchopulmonary dysplasia: lung clinical and pathological findings.

PubMed

Thomson, Merran A; Yoder, Bradley A; Winter, Vicki T; Giavedoni, Luis; Chang, Ling Yi; Coalson, Jacqueline J

2006-11-01

Using the 125-day baboon model of bronchopulmonary dysplasia treated with prenatal steroid and exogenous surfactant, we hypothesized that a delay of extubation from low tidal volume positive pressure ventilation to nasal continuous positive airway pressure at 5 days (delayed nasal continuous positive airway pressure group) would not induce more lung injury when compared with baboons aggressively weaned to nasal continuous positive airway pressure at 24 hours (early nasal continuous positive airway pressure group), because both received positive pressure ventilation. After delivery by cesarean section at 125 days (term: 185 days), infants received 2 doses of Curosurf (Chiesi Farmaceutica S.p.A., Parma, Italy) and daily caffeine citrate. The delay in extubation to 5 days resulted in baboons in the delayed nasal continuous positive airway pressure group having a lower arterial to alveolar oxygen ratio, high PaCO2, and worse respiratory function. The animals in the delayed nasal continuous positive airway pressure group exhibited a poor respiratory drive that contributed to more reintubations and time on mechanical ventilation. A few animals in both groups developed necrotizing enterocolitis and/or sepsis, but infectious pneumonias were not documented. Cellular bronchiolitis and peribronchiolar alveolar wall thickening were more frequently seen in the delayed nasal continuous positive airway pressure group. Bronchoalveolar lavage levels of interleukin-6, interleukin-8, monocyte chemotactic protein-1, macrophage inflammatory protein-1 alpha, and growth-regulated oncogene-alpha were significantly increased in the delayed nasal continuous positive airway pressure group. Standard and digital morphometric analyses showed no significant differences in internal surface area and nodal measurements between the groups. Platelet endothelial cell adhesion molecule vascular staining was not significantly different between the 2 nasal continuous positive airway pressure groups. Volutrauma and/or low-grade colonization of airways secondary to increased reintubations and ventilation times are speculated to play causative roles in the delayed nasal continuous positive airway pressure group findings.

Trauma Hemostasis and Oxygenation Research Network position paper on the role of hypotensive resuscitation as part of remote damage control resuscitation.

PubMed

Woolley, Thomas; Thompson, Patrick; Kirkman, Emrys; Reed, Richard; Ausset, Sylvain; Beckett, Andrew; Bjerkvig, Christopher; Cap, Andrew P; Coats, Tim; Cohen, Mitchell; Despasquale, Marc; Dorlac, Warren; Doughty, Heidi; Dutton, Richard; Eastridge, Brian; Glassberg, Elon; Hudson, Anthony; Jenkins, Donald; Keenan, Sean; Martinaud, Christophe; Miles, Ethan; Moore, Ernest; Nordmann, Giles; Prat, Nicolas; Rappold, Joseph; Reade, Michael C; Rees, Paul; Rickard, Rory; Schreiber, Martin; Shackelford, Stacy; Skogran Eliassen, Håkon; Smith, Jason; Smith, Mike; Spinella, Philip; Strandenes, Geir; Ward, Kevin; Watts, Sarah; White, Nathan; Williams, Steve

2018-06-01

The Trauma Hemostasis and Oxygenation Research (THOR) Network has developed a consensus statement on the role of permissive hypotension in remote damage control resuscitation (RDCR). A summary of the evidence on permissive hypotension follows the THOR Network position on the topic. In RDCR, the burden of time in the care of the patients suffering from noncompressible hemorrhage affects outcomes. Despite the lack of published evidence, and based on clinical experience and expertise, it is the THOR Network's opinion that the increase in prehospital time leads to an increased burden of shock, which poses a greater risk to the patient than the risk of rebleeding due to slightly increased blood pressure, especially when blood products are available as part of prehospital resuscitation.The THOR Network's consensus statement is, "In a casualty with life-threatening hemorrhage, shock should be reversed as soon as possible using a blood-based HR fluid. Whole blood is preferred to blood components. As a part of this HR, the initial systolic blood pressure target should be 100 mm Hg. In RDCR, it is vital for higher echelon care providers to receive a casualty with sufficient physiologic reserve to survive definitive surgical hemostasis and aggressive resuscitation. The combined use of blood-based resuscitation and limiting systolic blood pressure is believed to be effective in promoting hemostasis and reversing shock".

Experimental and Numerical Study of the Evaporation of Water at Low Pressures.

PubMed

Kazemi, Mohammad Amin; Nobes, David S; Elliott, Janet A W

2017-05-09

Although evaporation is considered to be a surface phenomenon, the rate of molecular transport across a liquid-vapor boundary is strongly dependent on the coupled fluid dynamics and heat transfer in the bulk fluids. Recent experimental thermocouple measurements of the temperature field near the interface of evaporating water into its vapor have begun to show the role of heat transfer in evaporation. However, the role of fluid dynamics has not been explored sufficiently. Here, we have developed a mathematical model to describe the coupling of the heat, mass, and momentum transfer in the fluids with the transport phenomena at the interface. The model was used to understand the experimentally obtained velocity field in the liquid and temperature profiles in the liquid and vapor, in evaporation from a concave meniscus for various vacuum pressures. By using the model, we have shown that an opposing buoyancy flow suppressed the thermocapillary flow in the liquid during evaporation at low pressures in our experiments. As such, in the absence of thermocapillary convection, the evaporation is controlled by heat transfer to the interface, and the predicted behavior of the system is independent of choosing between the existing theoretical expressions for evaporation flux. Furthermore, we investigated the temperature discontinuity at the interface and confirmed that the discontinuity strongly depends on the heat flux from the vapor side, which depends on the geometrical shape of the interface.

High Salt Intake Increases Blood Pressure in Normal Rats: Putative Role of 20-HETE and No Evidence on Changes in Renal Vascular Reactivity

PubMed Central

Walkowska, A.; Kuczeriszka, M.; Sadowski, J.; Olszyński, K.H.; Dobrowolski, L.; Červenka, L.; Hammock, B.D.; Kompanowska-Jezierska, E.

2015-01-01

Background/Aims High salt (HS) intake may elevate blood pressure (BP), also in animals without genetic salt sensitivity. The development of salt-dependent hypertension could be mediated by endogenous vasoactive agents; here we examined the role of vasodilator epoxyeicosatrienoic acids (EETs) and vasoconstrictor 20-hydroxyeicosatetraenoic acid (20-HETE). Methods In conscious Wistar rats on HS diet systolic BP (SBP) was examined after chronic elevation of EETs using 4-[4-(3-adamantan-1-yl-ureido)-cyclohexyloxy]-benzoic acid (c-AUCB), a blocker of soluble epoxide hydrolase, or after inhibition of 20-HETE with 1-aminobenzotriazole (ABT). Thereafter, in acute experiments the responses of renal artery blood flow (Transonic probe) and renal regional perfusion (laser-Doppler) to intrarenal acetylcholine (ACh) or norepinephrine were determined. Results HS diet increased urinary 20-HETE excretion. The SBP increase was not reduced by c-AUCB but prevented by ABT until day 5 of HS exposure. Renal vasomotor responses to ACh or norepinephrine were similar on standard and HS diet. ABT but not c-AUCB abolished the responses to ACh. Conclusions 20-HETE seems to mediate the early-phase HS diet-induced BP increase while EETs are not engaged in the process. Since HS exposure did not alter renal vasodilator responses to Ach, endothelial dysfunction is not a critical factor in the mechanism of salt-induced blood pressure elevation. PMID:26067851

Predictors of obesity and overweight in preschoolers: The role of parenting styles and feeding practices.

PubMed

Melis Yavuz, H; Selcuk, Bilge

2018-01-01

Childhood obesity/overweight (OB/OW) displayed a rapid increase and high prevalence in the last few decades in preschool-aged children, which raised health concerns across the world and motivated researchers to investigate the factors that underlie childhood obesity. The current study examined parenting styles and child-feeding practices as potential predictors for OB/OW in preschool children, controlling for child's temperament, which has been shown to be linked with OB/OW. The sample included 61 normal weight (NW) and 61 obese/overweight (OB/OW) Turkish pre-schoolers (M age = 62.2 months; SD = 7.64, range = 45-80 months). Parenting styles (authoritarian, authoritative), child-feeding practices (restriction, pressure to eat, monitoring), and child's temperament (negative affectivity) were measured with mothers' reports. Results showed that authoritarian parenting and maternal pressure to eat were the two parenting variables that significantly predicted child's weight status; the odds of being OB/OW was 4.71 times higher in children whose mothers used higher authoritarian parenting style, and was 0.44 times lower when mothers pressured their child to eat. These findings suggest that understanding the unique role of different aspects of parenting in the risk of early OB/OW status of children would be important in developing more effective interventions from early years in life. Copyright © 2017 Elsevier Ltd. All rights reserved.

Exploring emergency nurse practitioners' perceptions of their role.

PubMed

Bagley, Sue

2018-02-21

Since the 1980s, the emergency nurse practitioner (ENP) role has evolved as increasing socioeconomic pressures and changing government policy have led to new working practices in emergency departments. Similarly, a lack of consensus regarding educational support for ENPs and the regulation of ENP training, mean that variations remain in the scope of practice, role description and academic requirements for ENPs. To explore ENPs' perceptions of their changing role, including their educational requirements and whether their training needs are being met. This qualitative phenomenological study examined the views of six ENPs using semi-structured interviews. The study identified four themes: inadequate protected time for continuing professional development (CPD); importance of senior medical support in role expansion and CPD; inconsistent educational preparation for expanded roles; and the ENPs' perceived reasons for role expansion. Although all the participants stated that it was challenging to find time for CPD when working in busy clinical environments, this was regarded as less important than the positive effect of senior medical support for advanced roles. Over the past three decades, the ENP role has become well established, which has led to increased confidence, and the development of collaborative ways of working, among ENPs and their colleagues. However, while ENPs have embraced the challenges of their changing role, educational support has not been consistent. There are still disparities in ENPs' scope of practice, expectations of the role between services, and the educational preparation required to undertake the role. ©2018 RCN Publishing Company Ltd. All rights reserved. Not to be copied, transmitted or recorded in any way, in whole or part, without prior permission of the publishers.

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

Ahmad Ghassemi

Geothermal energy is recovered by circulating water through heat exchange areas within a hot rock mass. Geothermal reservoir rock masses generally consist of igneous and metamorphic rocks that have low matrix permeability. Therefore, cracks and fractures play a significant role in extraction of geothermal energy by providing the major pathways for fluid flow and heat exchange. Therefore, knowledge of the conditions leading to formation of fractures and fracture networks is of paramount importance. Furthermore, in the absence of natural fractures or adequate connectivity, artificial fractures are created in the reservoir using hydraulic fracturing. Multiple fractures are preferred because of themore » large size necessary when using only a single fracture. Although the basic idea is rather simple, hydraulic fracturing is a complex process involving interactions of high pressure fluid injections with a stressed hot rock mass, mechanical interaction of induced fractures with existing natural fractures, and the spatial and temporal variations of in-situ stress. As a result, it is necessary to develop tools that can be used to study these interactions as an integral part of a comprehensive approach to geothermal reservoir development, particularly enhanced geothermal systems. In response to this need we have developed advanced poro-thermo-chemo-mechanical fracture models for rock fracture research in support of EGS design. The fracture propagation models are based on a regular displacement discontinuity formulation. The fracture propagation studies include modeling interaction of induced fractures. In addition to the fracture propagation studies, two-dimensional solution algorithms have been developed and used to estimate the impact of pro-thermo-chemical processes on fracture permeability and reservoir pressure. Fracture permeability variation is studied using a coupled thermo-chemical model with quartz reaction kinetics. The model is applied to study quartz precipitation/dissolution, as well as the variation in fracture aperture and pressure. Also, a three-dimensional model of injection/extraction has been developed to consider the impact poro- and thermoelastic stresses on fracture slip and injection pressure. These investigations shed light on the processes involved in the observed phenomenon of injection pressure variation (e.g., in Coso), and allow the assessment of the potential of thermal and chemical stimulation strategies.« less

Salt-Sensitive Hypertension: Perspectives on Intrarenal Mechanisms

PubMed Central

Majid, Dewan S.A.; Prieto, Minolfa C.; Navar, L Gabriel

2015-01-01

Salt sensitive hypertension is characterized by increases in blood pressure in response to increases in dietary salt intake and is associated with an enhanced risk of cardiovascular and renal morbidity. Although researchers have sought for decades to understand how salt sensitivity develops in humans, the mechanisms responsible for the increases in blood pressure in response to high salt intake are complex and only partially understood. Until now, scientists have been unable to explain why some individuals are salt sensitive and others are salt resistant. Although a central role for the kidneys in the development of salt sensitivity and hypertension has been generally accepted, it is also recognized that hypertension is of multifactorial origin and a variety of factors can induce, or prevent, blood pressure responsiveness to the manipulation of salt intake. Excess salt intake in susceptible persons may also induce inappropriate central and sympathetic nervous system responses and increase the production of intrarenal angiotensin II, catecholamines and other factors such as oxidative stress and inflammatory cytokines. One key factor is the concomitant inappropriate or paradoxical activation of the intrarenal renin-angiotensin system, by high salt intake. This is reflected by the increases in urinary angiotensinogen during high salt intake in salt sensitive models. A complex interaction between neuroendocrine factors and the kidney may underlie the propensity for some individuals to retain salt and develop salt-dependent hypertension. In this review, we focus mainly on the renal contributions that provide the mechanistic link between chronic salt intake and the development of hypertension. PMID:26028244

Profile and predictor of health-related quality of life among hypertensive patients in south-western Nigeria.

PubMed

Ogunlana, Michael O; Adedokun, Babatunde; Dairo, Magbagbeola D; Odunaiya, Nse A

2009-06-17

The health-related quality of life (HRQOL) of hypertensives may be influenced by blood pressure, adverse effects of drugs used to treat hypertension, or other factors, such as the labelling effect, or beliefs and attitudes about illness and treatment. There is paucity of information on the determinants of HRQOL among black hypertensives especially in the developing countries such as Nigeria. This study describes the HRQOL and its determinants among black patients diagnosed and treated for Hypertension in Nigeria. The study was a cross sectional in design that involved 265 hypertensive patients receiving treatment at the medical outpatient unit of the Federal Medical Centre Abeokuta, Nigeria. They were all consecutive patients that presented at the hospital during the period of the study who meet the inclusion criteria and consented to participate in the study. Demographic data, disease characteristics such as symptoms and signs and recent drug history were obtained from the patients and their hospital records as documented by the physician. The SF-36 questionnaire was administered once by interview to the participants to measure their HRQOL. Descriptive statistics was used in summarizing the demographic data and hypertension related histories of the participants. Multiple linear regression was used to model for the influence of socio demographic and clinical variables of the hypertensives on their HRQOL. Physical functioning domain mean score was far below average (33.53 +/- 29.65). Role physical and role emotional domains were a little above average (54.7 +/- 40.4, 51.1 +/- 40.6 respectively). Role Physical (p = 0.043), Role Emotional (p = 0.003), Vitality (p = 0.014) and Mental Health (p = 0.034) domain mean scores for patients with controlled BP were significantly higher than patients with uncontrolled BP. The overall HRQOL was significantly better in the group of hypertensives with controlled blood pressure (p = 0.014). Increasing blood pressure (p = 0.005) and symptom count (p < 0.001), the presence of stroke (p = 0.008) and visual impairment (p = 0.015) were significant negative predictors of the overall HRQOL. This study provides evidence for a model that links patients' status with regard to biology (blood pressure), symptoms, and functionality (HRQOL) and may prove useful in guiding follow-up of patients who receive treatment for hypertension. Identification of patient's symptoms, blood pressure, complication/comorbidity and changes in functioning may help clinicians increase their effectiveness in helping patients maintain adherent behaviour with drug and non drug interventions in chronic diseases such as hypertension.

Experimental Thermodynamics of [Na-Mg-Cl-SO4] Aqueous Solutions at GPa Pressure With Application to Icy Worlds.

NASA Astrophysics Data System (ADS)

Brown, J. M.; Bollengier, O.; Vance, S.

2017-12-01

Water competes with silicates as the main constituent of solid bodies in the outer solar system. Ganymede and Titan, the Mercury-sized satellites of Jupiter and Saturn, are made up half of water present as massive hydrospheres where pressure can reach up to 1.5 GPa. Geophysical data and planetary models unequivocally support the existence of global aqueous oceans trapped in these hydrospheres. However, the extent of these oceans and their role in the processes governing the internal structure of these moons remain unresolved. At issue is the poor to non-existent characterization, at the relevant pressures, of the properties of the aqueous fluids of significance to the outer solar system (with notably the Na-Mg-Cl-SO4 salts found in primitive chondrites), forcing current models to rely on pure water only. Our team at the University of Washington has developed an experimental apparatus to acquire the speed of sound of aqueous solutions in the 0 - 0.7 GPa and 250 - 350 K pressure and temperature ranges covering most of the conditions of existence of these extra-terrestrial oceans. Speeds of sound measured over a grid of pressures and temperatures allow calculation of the thermodynamic quantities (G, ρ, μ...) required for planetary science. Early analysis of pure water samples indicates our experimental results are on par with (at lower pressures), or better than, the IAPWS water laboratory standard, with sound speeds determined to 0.02% over our entire pressure range. For the first time at the high pressures of interest for large icy moons, we achieved the exploration of H2O-NaCl, H2O-MgSO4, H2O-Na2SO4 and H2O-MgCl2 solutions, from dilute concentrations to saturation. We are now in the process of acquiring the first data for H2O-NaCl-MgSO4 mixtures. We will briefly present our experimental setup and the underlying sound speed theory, and will then compare our results for the four endmembers, with an emphasis on their different association behavior under pressure as revealed by the sound speed data. We also aim to provide the first insights into the mixing behavior of these ions in solution at high pressure, to be compared with common mixing rules. Finally, we will present an application of the thermodynamics of aqueous solutions to calculate liquid-ice equilibria and assess the role of brine densities in the evolution of icy mantles.

Toward an improved model of maple sap exudation: the location and role of osmotic barriers in sugar maple, butternut and white birch.

PubMed

Cirelli, Damián; Jagels, Richard; Tyree, Melvin T

2008-08-01

Two theories have been proposed to explain how high positive pressures are developed in sugar maple stems when temperatures fluctuate around freezing. The Milburn-O'Malley theory proposes that pressure development is purely physical and does not require living cells or sucrose. The osmotic theory invokes the involvement of living cells and sucrose to generate an osmotic pressure difference between fibers and vessels, which are assumed to be separated by an osmotic barrier. We analyzed wood of Acer saccharum Marsh., Juglans cinerea L. and Betula papyrifera Marsh. (all generate positive pressures) examining three critical components of the osmotic model: pits in cell walls, selectivity of the osmotic barrier and stability of air bubbles under positive xylem pressure. We examined the distribution and type of pits directly by light and scanning electron microscopy (SEM), and indirectly by perfusion of branch segments with fluorescent dyes with molecular masses similar to sucrose. The latter approach allowed us to use osmotic surrogates for sucrose that could be tracked by epifluorescence. Infusion experiments were used to assess the compartmentalization of sucrose and to determine the behavior of gas bubbles as predicted by Fick's and Henry's laws. The SEM images of sugar maple revealed a lack of pitting between fibers and vessels but connections between fiber-tracheids and vessels were present. Fluorescein-perfusion experiments demonstrated that large molecules do not diffuse into libriform fibers but are confined within the domain of vessels, parenchyma and fiber-tracheids. Results of the infusion experiments were in agreement with those of the fluorescein perfusions and further indicated the necessity of a compartmentalized osmolyte to drive stem pressure, as well as the inability of air bubbles to maintain such pressure because of instability. These results support the osmotic model and demonstrate that the secondary cell wall is an effective osmotic barrier for molecules larger than 300 g mol(-1).

Relationship between parental socio-economic status and casual blood pressure in coastal Nigerian adolescents.

PubMed

Ansa, V O; Anah, M U; Odey, F A; Mbu, P N; Agbor, E I

2010-01-01

Emerging data suggest that essential or primary hypertension occurs in the young. Parental socioeconomic status may play a role but the exact mechanisms still remain unclear. This study was aimed at determining the relationship between parental socioeconomic status and casual blood pressure in adolescents. One thousand and eight adolescents attending two secondary schools in Calabar, Nigeria were selected by stratified random sampling. Their blood pressure, weights and heights were taken using standard methods and sociodemographic data were obtained using a pretested semistructured questionnaire. Blood pressure was increased with age with males having higher values. The other major determinants of blood pressure were weight, height, body mass index, level of physical activity and parental socioeconomic status (p <0.05). No relationship was established between these determinants as well as dietary habits with parental socioeconomic status (p > 0.05). Female adolescents with parents in the lower socioeconomic classes had significantly higher systolic and diastolic blood pressure (p < 0.05). In contrast, parental socioeconomic status showed no significant relationship with systolic blood pressure and diastolic blood pressure in males (p >0.05).The prevalence of elevated blood pressure was higher in females than in males. Low parental socioeconomic status appear to be associated with higher casual blood pressure especially in female coastal Nigerian adolescents. Traditional determinants did not appear to play a significant role. Psychological stress arising from environmental and economic stressors may be responsible.

Probabilistic Fracture Mechanics of Reactor Pressure Vessels with Populations of Flaws

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

Spencer, Benjamin; Backman, Marie; Williams, Paul

This report documents recent progress in developing a tool that uses the Grizzly and RAVEN codes to perform probabilistic fracture mechanics analyses of reactor pressure vessels in light water reactor nuclear power plants. The Grizzly code is being developed with the goal of creating a general tool that can be applied to study a variety of degradation mechanisms in nuclear power plant components. Because of the central role of the reactor pressure vessel (RPV) in a nuclear power plant, particular emphasis is being placed on developing capabilities to model fracture in embrittled RPVs to aid in the process surrounding decisionmore » making relating to life extension of existing plants. A typical RPV contains a large population of pre-existing flaws introduced during the manufacturing process. The use of probabilistic techniques is necessary to assess the likelihood of crack initiation at one or more of these flaws during a transient event. This report documents development and initial testing of a capability to perform probabilistic fracture mechanics of large populations of flaws in RPVs using reduced order models to compute fracture parameters. The work documented here builds on prior efforts to perform probabilistic analyses of a single flaw with uncertain parameters, as well as earlier work to develop deterministic capabilities to model the thermo-mechanical response of the RPV under transient events, and compute fracture mechanics parameters at locations of pre-defined flaws. The capabilities developed as part of this work provide a foundation for future work, which will develop a platform that provides the flexibility needed to consider scenarios that cannot be addressed with the tools used in current practice.« less

Reversible Morphological Control of Tubulin-Encapsulating Giant Liposomes by Hydrostatic Pressure.

PubMed

Hayashi, Masahito; Nishiyama, Masayoshi; Kazayama, Yuki; Toyota, Taro; Harada, Yoshie; Takiguchi, Kingo

2016-04-19

Liposomes encapsulating cytoskeletons have drawn much recent attention to develop an artificial cell-like chemical-machinery; however, as far as we know, there has been no report showing isothermally reversible morphological changes of liposomes containing cytoskeletons because the sets of various regulatory factors, that is, their interacting proteins, are required to control the state of every reaction system of cytoskeletons. Here we focused on hydrostatic pressure to control the polymerization state of microtubules (MTs) within cell-sized giant liposomes (diameters ∼10 μm). MT is the cytoskeleton formed by the polymerization of tubulin, and cytoskeletal systems consisting of MTs are very dynamic and play many important roles in living cells, such as the morphogenesis of nerve cells and formation of the spindle apparatus during mitosis. Using real-time imaging with a high-pressure microscope, we examined the effects of hydrostatic pressure on the morphology of tubulin-encapsulating giant liposomes. At ambient pressure (0.1 MPa), many liposomes formed protrusions due to tubulin polymerization within them. When high pressure (60 MPa) was applied, the protrusions shrank within several tens of seconds. This process was repeatedly inducible (around three times), and after the pressure was released, the protrusions regenerated within several minutes. These deformation rates of the liposomes are close to the velocities of migrating or shape-changing living cells rather than the shortening and elongation rates of the single MTs, which have been previously measured. These results demonstrate that the elongation and shortening of protrusions of giant liposomes is repeatedly controllable by regulating the polymerization state of MTs within them by applying and releasing hydrostatic pressure.

High-frequency pressure variations in the vicinity of a surface CO2 flux chamber

Treesearch

Eugene S. Takle; James R. Brandle; R. A. Schmidt; Rick Garcia; Irina V. Litvina; William J. Massman; Xinhua Zhou; Geoffrey Doyle; Charles W. Rice

2003-01-01

We report measurements of 2Hz pressure fluctuations at and below the soil surface in the vicinity of a surface-based CO2 flux chamber. These measurements were part of a field experiment to examine the possible role of pressure pumping due to atmospheric pressure fluctuations on measurements of surface fluxes of CO2. Under the moderate wind speeds, warm temperatures,...

Real-Time Optical Monitoring of Flow Kinetics and Gas Phase Reactions Under High-Pressure OMCVD Conditions

NASA Technical Reports Server (NTRS)

Dietz, N.; McCall, S.; Bachmann, K. J.

2001-01-01

This contribution addresses the real-time optical characterization of gas flow and gas phase reactions as they play a crucial role for chemical vapor phase depositions utilizing elevated and high pressure chemical vapor deposition (HPCVD) conditions. The objectives of these experiments are to validate on the basis of results on real-time optical diagnostics process models simulation codes, and provide input parameter sets needed for analysis and control of chemical vapor deposition at elevated pressures. Access to microgravity is required to retain high pressure conditions of laminar flow, which is essential for successful acquisition and interpretation of the optical data. In this contribution, we describe the design and construction of the HPCVD system, which include access ports for various optical methods of real-time process monitoring and to analyze the initial stages of heteroepitaxy and steady-state growth in the different pressure ranges. To analyze the onset of turbulence, provisions are made for implementation of experimental methods for in-situ characterization of the nature of flow. This knowledge will be the basis for the design definition of experiments under microgravity, where gas flow conditions, gas phase and surface chemistry, might be analyzed by remote controlled real-time diagnostics tools, developed in this research project.

Positional circulatory control in the sleeping infant and toddler: role of the inner ear and arterial pulse pressure.

PubMed

Cohen, Gary; Vella, Silvano; Jeffery, Heather; Lagercrantz, Hugo; Katz-Salamon, Miriam

2012-08-01

Heart rate (HR) and arterial blood pressure (BP) are rapidly and reflexively adjusted as body position and the force/direction of gravity alters. Anomalies in these mechanisms may predispose to circulatory failure during sleep. We analysed the development of two key reflexes involved by undertaking a longitudinal (birth–1 year) comparison of instantaneous HR and BP changes evoked by abrupt upright, sideways or horizontal repositioning. Each manoeuvre triggered an identical rise in HR (tachycardia) followed by a slower rise in diastolic blood pressure (DBP)/systolic blood pressure (SBP) and variable pulse pressure (PP) change. We show that tachycardia is triggered by acceleration (vestibular) sensors located in the inner ear and slight changes in the pulsatile component of BP then signal to the arterial baroreceptors to reinforce or oppose these actions as needed. We also identified a PP anomaly in sleeping 1-year-olds of smokers that prematurely slows HR and is associated with mild positional hypotension. We conclude that positional circulatory compensation is initiated pre-emptively in a feed-forward manner and that feedback changes in vago-sympathetic drive to the heart (and perhaps blood vessels) by PP exert a slower but powerful modulating effect. An anomaly in either or both mechanisms may weaken positional compensation in some sleeping infants.

Role of low O 2 pressure and growth temperature on electrical transport of PLD grown ZnO thin films on Si substrates

NASA Astrophysics Data System (ADS)

Pandis, Ch.; Brilis, N.; Tsamakis, D.; Ali, H. A.; Krishnamoorthy, S.; Iliadis, A. A.

2006-06-01

Undoped ZnO thin films have been grown on (100) Si substrates by pulsed laser deposition. The effect of growth parameters such as temperature, O 2 partial pressure and laser fluence on the structural and electrical properties of the films has been investigated. It is shown that the well-known native n-type conductivity, attributed to the activation of hydrogenic donor states, exhibits a conversion from n-type to p-type when the O 2 partial pressure is reduced from 10 -4 to 10 -7 Torr at growth temperatures lower than 400 °C. The p-type conductivity could be attributed to the dominant role of the acceptor Zn vacancies for ZnO films grown at very low O 2 pressures.

Personality and gender differences in global perspective.

PubMed

Schmitt, David P; Long, Audrey E; McPhearson, Allante; O'Brien, Kirby; Remmert, Brooke; Shah, Seema H

2017-12-01

Men's and women's personalities appear to differ in several respects. Social role theories of development assume gender differences result primarily from perceived gender roles, gender socialization and sociostructural power differentials. As a consequence, social role theorists expect gender differences in personality to be smaller in cultures with more gender egalitarianism. Several large cross-cultural studies have generated sufficient data for evaluating these global personality predictions. Empirically, evidence suggests gender differences in most aspects of personality-Big Five traits, Dark Triad traits, self-esteem, subjective well-being, depression and values-are conspicuously larger in cultures with more egalitarian gender roles, gender socialization and sociopolitical gender equity. Similar patterns are evident when examining objectively measured attributes such as tested cognitive abilities and physical traits such as height and blood pressure. Social role theory appears inadequate for explaining some of the observed cultural variations in men's and women's personalities. Evolutionary theories regarding ecologically-evoked gender differences are described that may prove more useful in explaining global variation in human personality. © 2016 International Union of Psychological Science.

The Mars Development of a Micro-Isolation Valve

NASA Technical Reports Server (NTRS)

Mueller, Juergen; Vargo, Steven; Forgrave, John; Bame, David; Chakraborty, Indrani; Tang, William

1999-01-01

A feasibility investigation for a newly proposed microfabricated, normally-closed isolation valve was initiated. The micro-isolation valve is silicon based and relies on the principle of melting a silicon plug, opening an otherwise sealed flow passage. This valve may thus serve a similar role as a conventional pyrovalve and is intended for use in micropropulsion systems onboard future microspacecraft, having wet masses of no more than 10-20 kg, as well as in larger scale propulsion systems having only low flow rate requirements, such as ion propulsion or Hall thruster systems. Two key feasibility issues - melting of the plug and pressure handling capability - were addressed. Thermal finite element modeling showed that valves with plugs having widths between 10 and 50 gm have power requirements of only 10 . 30 Watts to open over a duration of 0.5 ms or less. Valve chips featuring 5 0 micron plugs were burst pressure tested and reached maximum pressure values o f 2900 psig (19.7 Mpa).

Accessing the Asymmetric Collisionless Reconnection Regime in the Terrestrial Reconnection Experiment (TREX)

NASA Astrophysics Data System (ADS)

Greess, S.; Egedal, J.; Olson, J.; Millet-Ayala, A.; Myers, R.; Wallace, J.; Clark, M.; Forest, C.

2017-12-01

Kinetic effects are expected to dominate the collisionless reconnection regime, where the mean free path is large enough that the anisotropic electron pressure can develop without being damped away by collisional pitch angle scattering. In simulations, the anisotropic pressure drives the formation of outflow jets [1]. These jets are expected to play a role in the reconnection layer at the Earth's magnetopause, which is currently being explored by Magnetospheric Multiscale Mission (MMS) [2]. Until recently, this regime of anisotropic pressure was inaccessible by laboratory experiments, but new data from the Terrestrial Reconnection Experiment (TREX) shows that fully collisionless reconnection can now be achieved in the laboratory. Future runs at TREX will delve deeper into this collisionless regime in both the antiparallel and guide-field cases. [1] Le, A. et al. JPP, 81(1). doi: 10.1017/S0022377814000907. [2] Burch, J. L. et al. Space Sci. Rev. 199,5. doi: 10.1007/s11214-015-0164-9 Supported in part by NSF/DOE award DE-SC0013032.

X-Ray Crystallography as a Tool to Determine Three-Dimensional Structures of Commercial Enzymes Subjected to Treatment in Pressurized Fluids.

PubMed

Feiten, Mirian Cristina; Di Luccio, Marco; Santos, Karine F; de Oliveira, Débora; Oliveira, J Vladimir

2017-06-01

The study of enzyme function often involves a multi-disciplinary approach. Several techniques are documented in the literature towards determining secondary and tertiary structures of enzymes, and X-ray crystallography is the most explored technique for obtaining three-dimensional structures of proteins. Knowledge of three-dimensional structures is essential to understand reaction mechanisms at the atomic level. Additionally, structures can be used to modulate or improve functional activity of enzymes by the production of small molecules that act as substrates/cofactors or by engineering selected mutants with enhanced biological activity. This paper presentes a short overview on how to streamline sample preparation for crystallographic studies of treated enzymes. We additionally revise recent developments on the effects of pressurized fluid treatment on activity and stability of commercial enzymes. Future directions and perspectives on the the role of crystallography as a tool to access the molecular mechanisms underlying enzymatic activity modulation upon treatment in pressurized fluids are also addressed.

Pain thresholds and tenderness in neck and head following acute whiplash injury: a prospective study.

PubMed

Kasch, H; Stengaard-Pedersen, K; Arendt-Nielsen, L; Staehelin Jensen, T

2001-04-01

OBJECTIVE OF THE INVESTIGATION: In a 6-month prospective study of 141 consecutive acute whiplash-injured participants, and 40 acute, ankle-injured controls, pain and tenderness in the neck/head, and at a distant control site, were measured. Muscle palpation and pressure algometry in five head/neck muscle-pairs were performed after 1 week and 1, 3 and 6 months after injury. Algometry was performed at a distant control site. Whiplash-injured patients had lowered pressure-pain-detection thresholds and higher palpation-score initially in the neck/head, but the groups were similar after 6 months, and the control site was not sensitized. Focal, but not generalized, sensitization to musculoskeletal structure is present until 3 months, but not 6 months, after whiplash injury, and probably does not play a major role in the development of late whiplash syndrome. Pressure algometry and palpation are useful clinical tools in the evaluation of neck and jaw pain in acute whiplash injury.

Portal hypertension: a review of portosystemic collateral pathways and endovascular interventions.

PubMed

Pillai, A K; Andring, B; Patel, A; Trimmer, C; Kalva, S P

2015-10-01

The portal vein is formed at the confluence of the splenic and superior mesenteric vein behind the head of the pancreas. Normal blood pressure within the portal system varies between 5 and 10 mmHg. Portal hypertension is defined when the gradient between the portal and systemic venous blood pressure exceeds 5 mmHg. The most common cause of portal hypertension is cirrhosis. In cirrhosis, portal hypertension develops due to extensive fibrosis within the liver parenchyma causing increased vascular resistance. In addition, the inability of the liver to metabolise certain vasodilators leads to hyperdynamic splanchnic circulation resulting in increased portal blood flow. Decompression of the portal pressure is achieved by formation of portosystemic collaterals. In this review, we will discuss the pathophysiology, anatomy, and imaging findings of spontaneous portosystemic collaterals and clinical manifestations of portal hypertension with emphasis on the role of interventional radiology in the management of complications related to portal hypertension. Copyright © 2015 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

Three-dimensional numerical simulation for plastic injection-compression molding

NASA Astrophysics Data System (ADS)

Zhang, Yun; Yu, Wenjie; Liang, Junjie; Lang, Jianlin; Li, Dequn

2018-03-01

Compared with conventional injection molding, injection-compression molding can mold optical parts with higher precision and lower flow residual stress. However, the melt flow process in a closed cavity becomes more complex because of the moving cavity boundary during compression and the nonlinear problems caused by non-Newtonian polymer melt. In this study, a 3D simulation method was developed for injection-compression molding. In this method, arbitrary Lagrangian- Eulerian was introduced to model the moving-boundary flow problem in the compression stage. The non-Newtonian characteristics and compressibility of the polymer melt were considered. The melt flow and pressure distribution in the cavity were investigated by using the proposed simulation method and compared with those of injection molding. Results reveal that the fountain flow effect becomes significant when the cavity thickness increases during compression. The back flow also plays an important role in the flow pattern and redistribution of cavity pressure. The discrepancy in pressures at different points along the flow path is complicated rather than monotonically decreased in injection molding.

Pressure Decay Testing Methodology for Quantifying Leak Rates of Full-Scale Docking System Seals

NASA Technical Reports Server (NTRS)

Dunlap, Patrick H., Jr.; Daniels, Christopher C.; Wasowski, Janice L.; Garafolo, Nicholas G.; Penney, Nicholas; Steinetz, Bruce M.

2010-01-01

NASA is developing a new docking system to support future space exploration missions to low-Earth orbit and the Moon. This system, called the Low Impact Docking System, is a mechanism designed to connect the Orion Crew Exploration Vehicle to the International Space Station, the lunar lander (Altair), and other future Constellation Project vehicles. NASA Glenn Research Center is playing a key role in developing the main interface seal for this docking system. This seal will be relatively large with an outside diameter in the range of 54 to 58 in. (137 to 147 cm). As part of this effort, a new test apparatus has been designed, fabricated, and installed to measure leak rates of candidate full-scale seals under simulated thermal, vacuum, and engagement conditions. Using this test apparatus, a pressure decay testing and data processing methodology has been developed to quantify full-scale seal leak rates. Tests performed on untreated 54 in. diameter seals at room temperature in a fully compressed state resulted in leak rates lower than the requirement of less than 0.0025 lbm, air per day (0.0011 kg/day).

Bluetooth Low Energy Peripheral Android Health App for Educational and Interoperability Testing Purposes.

PubMed

Frohner, Matthias; Urbauer, Philipp; Sauermann, Stefan

2017-01-01

Based on recent telemonitoring activities in Austria for enabling integrated health care, the communication interfaces between personal health devices (e.g. blood pressure monitor) and personal health gateway devices (e.g. smartphone, routing received information to wide area networks) play an important role. In order to ease testing of the Bluetooth Low Energy interface functionality of the personal health gateway devices, a personal health device simulator was developed. Based on specifications from the Bluetooth SIG a XML software test configuration file structure is defined that declares the specific features of the personal health devices simulated. Using this configuration file, different scenarios are defined, e.g. send a single measurement result from a blood pressure reading or sending multiple (historic) weight scale readings. The simulator is intended to be used for educational purposes in lectures, where the number of physical personal health devices can be reduced and learning can be improved. It could be shown that this simulator assists the development process of mHealth applications by reducing the time needed for development and testing.

Exploring the role of pain as an early predictor of category 2 pressure ulcers: a prospective cohort study.

PubMed

Smith, Isabelle L; Brown, Sarah; McGinnis, Elizabeth; Briggs, Michelle; Coleman, Susanne; Dealey, Carol; Muir, Delia; Nelson, E Andrea; Stevenson, Rebecca; Stubbs, Nikki; Wilson, Lyn; Brown, Julia M; Nixon, Jane

2017-01-20

To explore pressure area related pain as a predictor of category ≥2 pressure ulcer (PU) development. Multicentre prospective cohort study. UK hospital and community settings. Consenting acutely ill patients aged ≥18 years, defined as high risk (Braden bedfast/chairfast AND completely immobile/very limited mobility; pressure area related pain or; category 1 PU). Patients too unwell, unable to report pain, 2 or more category ≥2 PUs. Twice weekly for 30 days. Development and time to development of one or more category ≥2 PUs. Of 3819 screened, 1266 were eligible, 634 patients were recruited, 32 lost to follow-up, providing a 602 analysis population. 152 (25.2%) developed one or more category ≥2 PUs. 464 (77.1%) patients reported pressure area related pain on a healthy, altered or category 1 skin site of whom 130 (28.0%) developed a category ≥2 PU compared with 22 (15.9%) of those without pain. Full stepwise variable selection was used throughout the analyses. (1) Multivariable logistic regression model to assess 9 a priori factors: presence of category 1 PU (OR=3.25, 95% CI (2.17 to 4.86), p<0.0001), alterations to intact skin (OR=1.98, 95% CI (1.30 to 3.00), p=0.0014), pressure area related pain (OR=1.56, 95% CI (0.93 to 2.63), p=0.0931). (2) Multivariable logistic regression model to account for overdispersion: presence of category 1 PU (OR=3.20, 95% CI (2.11 to 4.85), p<0.0001), alterations to intact skin (OR=1.90, 95% CI (1.24 to 2.91), p=0.0032), pressure area related pain (OR=1.85, 95% CI (1.07 to 3.20), p=0.0271), pre-existing category 2 PU (OR=2.09, 95% CI (1.35 to 3.23), p=0.0009), presence of chronic wound (OR=1.66, 95% CI (1.06 to 2.62), p=0.0277), Braden activity (p=0.0476). (3) Accelerated failure time model: presence of category 1 PU (AF=2.32, 95% CI (1.73 to 3.12), p<0.0001), pressure area related pain (AF=2.28, 95% CI (1.59 to 3.27), p<0.0001). (4) 2-level random-intercept logistic regression model: skin status which comprised 2 levels (versus healthy skin); alterations to intact skin (OR=4.65, 95% CI (3.01 to 7.18), p<0.0001), presence of category 1 PU (OR=17.30, 95% CI (11.09 to 27.00), p<0.0001) and pressure area related pain (OR=2.25, 95% CI (1.53 to 3.29), p<0.0001). This is the first study to assess pain as a predictor of category ≥2 PU development. In all 4 models, pain emerged as a risk factor associated with an increased probability of category ≥2 PU development. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

The curvilinear relationship between work pressure and momentary task performance: the role of state and trait core self-evaluations.

PubMed

Hofmans, Joeri; Debusscher, Jonas; Dóci, Edina; Spanouli, Andromachi; De Fruyt, Filip

2015-01-01

Whereas several studies have demonstrated that core self-evaluations (CSE)-or one's appraisals about one's own self-worth, capabilities, and competences-relate to job outcomes, less is known about the mechanisms underlying these relationships. In the present study, we address this issue by examining the role of within- and between-person variation in CSE in the relationship between work pressure and task performance. We hypothesized that (a) work pressure relates to task performance in a curvilinear way, (b) state CSE mediates the curvilinear relationship between work pressure and task performance, and (c) the relationship between work pressure and state CSE is moderated by trait CSE. Our hypotheses were tested via a 10-day daily diary study with 55 employees in which trait CSE was measured at baseline, while work pressure, task performance, and state CSE were assessed on a daily basis. Bayesian multilevel path analysis showed that work pressure affects task performance via state CSE, with state CSE increasing as long as the employee feels that (s)he is able to handle the work pressure, while it decreases when the level of work pressure exceeds the employees' coping abilities. Moreover, we found that for people low on trait CSE, the depleting effect of work pressure via state CSE happens for low levels of work pressure, while for people high in trait CSE the depleting effect is located at high levels of work pressure. Together, our findings suggest that the impact of work pressure on task performance is driven by a complex interplay of between- and within-person differences in CSE.

Coping with increasing water and land resources limitation for meeting world's food needs: the role of virtual water and virtual land trade

NASA Astrophysics Data System (ADS)

Soriano, Barbara; Garrido, Alberto; Novo, Paula

2013-04-01

Increasing pressure to expand agriculture production is giving rise to renewed interest to obtain access to land and water resources in the world. Water footprint evaluations show the importance of green water in global food trade and production. Green water and land are almost inseparable resources. In this work we analyse the role of foreign direct investment and cooperation programmes from developed countries in developing counties, focusing on virtual water trade and associated resources. We develop econometric models with the aim to explain observed trends in virtual water exports from developing countries as explained by the inverse flow of investments and cooperation programmes. We analyse the main 19 emerging food exporters, from Africa, Asia and America, using 15 years of data. Results show that land per capita availability and foreign direct investments explain observed flows of virtual water exports. However, there is no causality with these and flows cooperation investments. Our analysis sheds light on the underlying forces explaining the phenomenon of land grab, which is the appropriation of land access in developing countries by food-importers.

Injectable hydrogels with high fixed charge density and swelling pressure for nucleus pulposus repair: biomimetic glycosaminoglycan analogues.

PubMed

Sivan, S S; Roberts, S; Urban, J P G; Menage, J; Bramhill, J; Campbell, D; Franklin, V J; Lydon, F; Merkher, Y; Maroudas, A; Tighe, B J

2014-03-01

The load-bearing biomechanical role of the intervertebral disc is governed by the composition and organization of its major macromolecular components, collagen and aggrecan. The major function of aggrecan is to maintain tissue hydration, and hence disc height, under the high loads imposed by muscle activity and body weight. Key to this role is the high negative fixed charge of its glycosaminoglycan side chains, which impart a high osmotic pressure to the tissue, thus regulating and maintaining tissue hydration and hence disc height under load. In degenerate discs, aggrecan degrades and is lost from the disc, particularly centrally from the nucleus pulposus. This loss of fixed charge results in reduced hydration and loss of disc height; such changes are closely associated with low back pain. The present authors developed biomimetic glycosaminoglycan analogues based on sulphonate-containing polymers. These biomimetics are deliverable via injection into the disc where they polymerize in situ, forming a non-degradable, nuclear "implant" aimed at restoring disc height to degenerate discs, thereby relieving back pain. In vitro, these glycosaminoglycan analogues possess appropriate fixed charge density, hydration and osmotic responsiveness, thereby displaying the capacity to restore disc height and function. Preliminary biomechanical tests using a degenerate explant model showed that the implant adapts to the space into which it is injected and restores stiffness. These hydrogels mimic the role taken by glycosaminoglycans in vivo and, unlike other hydrogels, provide an intrinsic swelling pressure, which can maintain disc hydration and height under the high and variable compressive loads encountered in vivo. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

PC-PLC/sphingomyelin synthase activity plays a central role in the development of myogenic tone in murine resistance arteries

PubMed Central

Zacharia, Joseph; Fairfax, Seth; Wier, Withrow Gil

2015-01-01

Myogenic tone is an intrinsic property of the vasculature that contributes to blood pressure control and tissue perfusion. Earlier investigations assigned a key role in myogenic tone to phospholipase C (PLC) and its products, inositol 1,4,5-trisphosphate (IP3) and diacylglycerol (DAG). Here, we used the PLC inhibitor, U-73122, and two other, specific inhibitors of PLC subtypes (PI-PLC and PC-PLC) to delineate the role of PLC in myogenic tone of pressurized murine mesenteric arteries. U-73122 inhibited depolarization-induced contractions (high external K+ concentration), thus confirming reports of nonspecific actions of U-73122 and its limited utility for studies of myogenic tone. Edelfosine, a specific inhibitor of PI-PLC, did not affect depolarization-induced contractions but modulated myogenic tone. Because PI-PLC produces IP3, we investigated the effect of blocking IP3 receptor-mediated Ca2+ release on myogenic tone. Incubation of arteries with xestospongin C did not affect tone, consistent with the virtual absence of Ca2+ waves in arteries with myogenic tone. D-609, an inhibitor of PC-PLC and sphingomyelin synthase, strongly inhibited myogenic tone and had no effect on depolarization-induced contraction. D-609 appeared to act by lowering cytoplasmic Ca2+ concentration to levels below those that activate contraction. Importantly, incubation of pressurized arteries with a membrane-permeable analog of DAG induced vasoconstriction. The results therefore mandate a reexamination of the signaling pathways activated by the Bayliss mechanism. Our results suggest that PI-PLC and IP3 are not required in maintaining myogenic tone, but DAG, produced by PC-PLC and/or SM synthase, is likely through multiple mechanisms to increase Ca2+ entry and promote vasoconstriction. PMID:25888510

Reactive Oxygen Species, Vascular Noxs, and Hypertension: Focus on Translational and Clinical Research

PubMed Central

Montezano, Augusto C.

2014-01-01

Abstract Significance: Reactive oxygen species (ROS) are signaling molecules that are important in physiological processes, including host defense, aging, and cellular homeostasis. Increased ROS bioavailability and altered redox signaling (oxidative stress) have been implicated in the onset and/or progression of chronic diseases, including hypertension. Recent Advances: Although oxidative stress may not be the only cause of hypertension, it amplifies blood pressure elevation in the presence of other pro-hypertensive factors, such as salt loading, activation of the renin-angiotensin-aldosterone system, and sympathetic hyperactivity, at least in experimental models. A major source for ROS in the cardiovascular-renal system is a family of nicotinamide adenine dinucleotide phosphate oxidases (Noxs), including the prototypic Nox2-based Nox, and Nox family members: Nox1, Nox4, and Nox5. Critical Issues: Although extensive experimental data support a role for increased ROS levels and altered redox signaling in the pathogenesis of hypertension, the role in clinical hypertension is unclear, as a direct causative role of ROS in blood pressure elevation has yet to be demonstrated in humans. Nevertheless, what is becoming increasingly evident is that abnormal ROS regulation and aberrant signaling through redox-sensitive pathways are important in the pathophysiological processes which is associated with vascular injury and target-organ damage in hypertension. Future Directions: There is a paucity of clinical information related to the mechanisms of oxidative stress and blood pressure elevation, and a few assays accurately measure ROS directly in patients. Such further ROS research is needed in humans and in the development of adequately validated analytical methods to accurately assess oxidative stress in the clinic. Antioxid. Redox Signal. 20, 164–182. PMID:23600794

Consumption of Green Coffee Reduces Blood Pressure and Body Composition by Influencing 11β-HSD1 Enzyme Activity in Healthy Individuals: A Pilot Crossover Study Using Green and Black Coffee

PubMed Central

Revuelta-Iniesta, R.; Al-Dujaili, E. A. S.

2014-01-01

Dietary polyphenols may have a protective role against the development of CVD. Thus, we aimed to investigate the effects of green coffee (GC), rich in chlorogenic acid, and black coffee (BC) on cardiovascular markers. A randomised pilot crossover study was performed on healthy subjects who consumed both coffees for 2 weeks. We measured anthropometry, blood pressure, and arterial elasticity after each intervention and collected urine samples to monitor antioxidant capacity. Free cortisol and cortisone levels were obtained from urine and analysed by specific ELISA methods. Systolic blood pressure (P = 0.018) and arterial elasticity (P = 0.001) were significantly reduced after GC. BMI (P = 0.04 for BC; P = 0.01 for GC) and abdominal fat (P = 0.01 for BC; P = 0.009 for GC) were also significantly reduced with no changes in energy intake. Urinary free cortisol was significantly reduced from 125.6 ± 85.9 nmol/day to 76.0 ± 54.9 nmol/day following GC and increased to 132.1 ± 89.1 nmol/day after BC. Urinary free cortisone increased by 18% following BC and 9% following GC (nonsignificant). Cortisol/cortisone ratio (indicating 11β-HSD1 activity) was reduced after GC (from 3.5 ± 1.9 to 1.7 ± 1.04, P = 0.002). This suggests that GC can play a role in reducing cardiovascular risk factors. Further research including hypertensive and overweight individuals will now be justified to clarify whether GC could have a therapeutic role in CVD. PMID:25133164

Ignition of PTFE-lined flexible hoses by rapid pressurization with oxygen

NASA Technical Reports Server (NTRS)

Janoff, Dwight; Bamford, Larry J.; Newton, Barry E.; Bryan, Coleman J.

1989-01-01

A high-volume pneumatic-impact system has been used to test PTFE-lined stainless steel braided hoses, in order to characterize the roles played in the mechanism of oxygen-induced ignition by impact pressure, pressurization rate, and upstream and downstream volumes of the hose. Ignitions are noted to have occurred at impact pressures well below the working pressure of the hoses, as well as at pressurization rates easily obtainable through manual operation of valves. The use of stainless steel hardlines downstream of the hose prevented ignitions at all pressures and pressurization rates; internal observations have shown evidence of shock ionization in the oxygen prior to ignition.

Ignition of PTFE-lined flexible hoses by rapid pressurization with oxygen

NASA Astrophysics Data System (ADS)

Janoff, Dwight; Bamford, Larry J.; Newton, Barry E.; Bryan, Coleman J.

A high-volume pneumatic-impact system has been used to test PTFE-lined stainless steel braided hoses, in order to characterize the roles played in the mechanism of oxygen-induced ignition by impact pressure, pressurization rate, and upstream and downstream volumes of the hose. Ignitions are noted to have occurred at impact pressures well below the working pressure of the hoses, as well as at pressurization rates easily obtainable through manual operation of valves. The use of stainless steel hardlines downstream of the hose prevented ignitions at all pressures and pressurization rates; internal observations have shown evidence of shock ionization in the oxygen prior to ignition.

Propagule pressure and stream characteristics influence introgression: Cutthroat and rainbow trout in British Columbia

USGS Publications Warehouse

Bennett, S.N.; Olson, J.R.; Kershner, J.L.; Corbett, P.

2010-01-01

Hybridization and introgression between introduced and native salmonids threaten the continued persistence of many inland cutthroat trout species. Environmental models have been developed to predict the spread of introgression, but few studies have assessed the role of propagule pressure. We used an extensive set of fish stocking records and geographic information system (GIS) data to produce a spatially explicit index of potential propagule pressure exerted by introduced rainbow trout in the Upper Kootenay River, British Columbia, Canada. We then used logistic regression and the information-theoretic approach to test the ability of a set of environmental and spatial variables to predict the level of introgression between native westslope cutthroat trout and introduced rainbow trout. Introgression was assessed using between four and seven co-dominant, diagnostic nuclear markers at 45 sites in 31 different streams. The best model for predicting introgression included our GIS propagule pressure index and an environmental variable that accounted for the biogeoclimatic zone of the site (r2 = 0.62). This model was 1.4 times more likely to explain introgression than the next-best model, which consisted of only the propagule pressure index variable. We created a composite model based on the model-averaged results of the seven top models that included environmental, spatial, and propagule pressure variables. The propagule pressure index had the highest importance weight (0.995) of all variables tested and was negatively related to sites with no introgression. This study used an index of propagule pressure and demonstrated that propagule pressure had the greatest influence on the level of introgression between a native and introduced trout in a human-induced hybrid zone. ?? 2010 by the Ecological Society of America.

Desoxycorticosterone pivalate-salt treatment leads to non-dipping hypertension in Per1 knockout mice.

PubMed

Solocinski, K; Holzworth, M; Wen, X; Cheng, K-Y; Lynch, I J; Cain, B D; Wingo, C S; Gumz, M L

2017-05-01

Increasing evidence demonstrates that circadian clock proteins are important regulators of physiological functions including blood pressure. An established risk factor for developing cardiovascular disease is the absence of a blood pressure dip during the inactive period. The goal of the present study was to determine the effects of a high salt diet plus mineralocorticoid on PER1-mediated blood pressure regulation in a salt-resistant, normotensive mouse model, C57BL/6J. Blood pressure was measured using radiotelemetry. After control diet, wild-type (WT) and Per1 (KO) knockout mice were given a high salt diet (4% NaCl) and the long-acting mineralocorticoid deoxycorticosterone pivalate. Blood pressure and activity rhythms were analysed to evaluate changes over time. Blood pressure in WT mice was not affected by a high salt diet plus mineralocorticoid. In contrast, Per1 KO mice exhibited significantly increased mean arterial pressure (MAP) in response to a high salt diet plus mineralocorticoid. The inactive/active phase ratio of MAP in WT mice was unchanged by high salt plus mineralocorticoid treatment. Importantly, this treatment caused Per1 KO mice to lose the expected decrease or 'dip' in blood pressure during the inactive compared to the active phase. Loss of PER1 increased sensitivity to the high salt plus mineralocorticoid treatment. It also resulted in a non-dipper phenotype in this model of salt-sensitive hypertension and provides a unique model of non-dipping. Together, these data support an important role for the circadian clock protein PER1 in the modulation of blood pressure in a high salt/mineralocorticoid model of hypertension. © 2016 Scandinavian Physiological Society. Published by John Wiley & Sons Ltd.

Analysing the socioeconomic determinants of hypertension in South Africa: a structural equation modelling approach

PubMed Central

2014-01-01

Background Epidemiological research has long observed a varying prevalence of hypertension across socioeconomic strata. However, patterns of association and underlying causal mechanisms are poorly understood in sub-Saharan Africa. Using education and income as indicators, we investigated the extent to which socioeconomic status is linked to blood pressure in the first wave of the National Income Dynamics Study — a South African longitudinal study of more than 15000 adults – and whether bio-behavioural risk factors mediate the association. Methods In a cross-sectional analysis, structural equation modelling was employed to estimate the effect of socioeconomic status on systolic and diastolic blood pressure and to assess the role of a set of bio-behavioural risk factors in explaining the observed relationships. Results After adjustment for age, race and antihypertensive treatment, higher education and income were independently associated with higher diastolic blood pressure in men. In women higher education predicted lower values of both diastolic and systolic blood pressure while higher income predicted lower systolic blood pressure. In both genders, body mass index was a strong mediator of an adverse indirect effect of socioeconomic status on blood pressure. Together with physical exercise, alcohol use, smoking and resting heart rate, body mass index therefore contributed substantially to mediation of the observed relationships in men. By contrast, in women unmeasured factors played a greater role. Conclusion In countries undergoing epidemiological transition, effects of socioeconomic status on blood pressure may vary by gender. In women, factors other than those listed above may have substantial role in mediating the association and merit investigation. PMID:24885860

The role of modifier cation field strength, oxygen speciation and network cation interaction in pressure-induced structural changes of silicate melts and glasses: 27Al, and 11B MAS NMR studies

NASA Astrophysics Data System (ADS)

Bista, S.; Stebbins, J. F.

2017-12-01

In aluminosilicate melts and glasses, both non-bridging oxygen content (NBO) and modifier cation field strength (Mg>Ca>Na>K) are known to facilitate network cation (e.g. Al, B) coordination increase with pressure. However, the role of these two compositional parameters in pressure-induced structural changes is derived from data for a limited set of compositions, where effects of the interaction between these parameters is less understood. For example, the effects of NBO are largely based on studies of Na and K aluminosilicate glasses, but effects of geologically important, higher field strength modifier cations such as Mg2+ and Fe2+ could well be significantly different. In this study, we look at a wide compositional range of Na, Ca and Mg aluminosilicate glasses (quenched from high pressure melts near to the glass transition temperature) to understand the roles of NBO and modifier cation field strength that can extend our view of processes important for silicate melts common in nature. Our results show that the role of NBO in pressure-induced structural changes varies systematically with increasing field strength of the modifier cation. In Na aluminosilicate glasses recovered from 1.5 to 3 GPa, large increases in average aluminum coordination are observed in glasses with high NBO content, while no detectable increases are seen for low nominal NBO (jadeite). In contrast, Mg aluminosilicate glasses with both high and low NBO show similar, large increases in average aluminum coordination with increasing pressure. The behaviors of Ca aluminosilicates fall between those of Na and Mg-rich glasses. We have also looked at interactions between different network forming cations in pressure-induced structural changes in low NBO Ca-aluminoborosilicate glasses with varying B/Si. Both aluminum and boron increase dramatically in coordination in these compositions 1.5 to 3 GPa. Increases in both average aluminum coordination and densification are larger in compositions containing higher boron concentrations, suggesting an interaction between boron and aluminum network cations in pressure-induced structural changes.

Amino Acids That Centrally Influence Blood Pressure and Regional Blood Flow in Conscious Rats

PubMed Central

Takemoto, Yumi

2012-01-01

Functional roles of amino acids have increasingly become the focus of research. This paper summarizes amino acids that influence cardiovascular system via the brain of conscious rats. This paper firstly describes why amino acids are selected and outlines how the brain regulates blood pressure and regional blood flow. This section includes a concise history of amino acid neurotransmitters in cardiovascular research and summarizes brain areas where chemical stimulations produce blood pressure changes mainly in anesthetized animals. This is followed by comments about findings regarding several newly examined amino acids with intracisternal stimulation in conscious rats that produce changes in blood pressure. The same pressor or depressor response to central amino acid stimulations can be produced by distinct mechanisms at central and peripheral levels, which will be briefly explained. Thereafter, cardiovascular actions of some of amino acids at the mechanism level will be discussed based upon findings of pharmacological and regional blood flow measurements. Several examined amino acids in addition to the established neurotransmitter amino acids appear to differentially activate brain structures to produce changes in blood pressure and regional blood flows. They may have physiological roles in the healthy brain, but pathological roles in the brain with cerebral vascular diseases such as stroke where the blood-brain barrier is broken. PMID:22690328

Frontostriatal development and probabilistic reinforcement learning during adolescence.

PubMed

DePasque, Samantha; Galván, Adriana

2017-09-01

Adolescence has traditionally been viewed as a period of vulnerability to increased risk-taking and adverse outcomes, which have been linked to neurobiological maturation of the frontostriatal reward system. However, growing research on the role of developmental changes in the adolescent frontostriatal system in facilitating learning will provide a more nuanced view of adolescence. In this review, we discuss the implications of existing research on this topic for learning during adolescence, and suggest that the very neural changes that render adolescents vulnerable to social pressure and risky decision making may also stand to play a role in scaffolding the ability to learn from rewards and from performance-related feedback. Copyright © 2017 Elsevier Inc. All rights reserved.

Regulatory mechanisms in arterial hypertension: role of microRNA in pathophysiology and therapy.

PubMed

Klimczak, Dominika; Jazdzewski, Krystian; Kuch, Marek

2017-02-01

Multiple factors underlie the pathophysiology of hypertension, involving endothelial dysregulation, vascular smooth muscle dysfunction, increased oxidative stress, sympathetic nervous system activation and altered renin -angiotensin -aldosterone regulatory activity. A class of non-coding RNA called microRNA, consisting of 17-25 nucleotides, exert regulatory function over these processes. This paper summarizes the currently available data from preclinical and clinical studies on miRNA in the development of hypertension as well as the impact of anti-hypertensive treatment on their plasma expression. We present microRNAs' characteristics, their biogenesis and role in the regulation of blood pressure together with their potential diagnostic and therapeutic application in clinical practice.

Translational medicine: the antihypertensive effect of renal denervation.

PubMed

DiBona, Gerald F; Esler, Murray

2010-02-01

Translational medicine is concerned with the translation of research discoveries into clinical applications for the prevention, diagnosis, and treatment of human diseases. Here we briefly review the research concerning the role of the renal sympathetic nerves (efferent and afferent) in the control of renal function, with particular reference to hypertension. The accumulated evidence is compelling for a primary role of the renal innervation in the pathogenesis of hypertension. These research discoveries led to the development of a catheter-based procedure for renal denervation in human subjects. A proof-of-principle study in patients with hypertension resistant to conventional therapy has demonstrated that the procedure is safe and produces renal denervation with sustained lowering of arterial pressure.

[Pathophysiological role of tissue renin-angiotensin-aldosterone system (RAAS) in human atherosclerosis].

PubMed

Fukui, Kensuke; Yamada, Hiroyuki; Matsubara, Hiroaki

2012-09-01

Renin-angiotensin-aldosterone system (RAAS) has been demonstrated to play an important role in the pathogenesis of atherosclerosis development both in animal experiments and in clinical studies. Numerous clinical studies have shown that blockade of RAAS exerts beneficial effects to restore the impaired endothelial function and to reduce the mortality and morbidity of cardiovascular diseases beyond their blood pressure lowering effect. However, the underlying mechanisms of stabilizing vulnerable plaque and inhibiting plaque rupture associated with acute coronary syndrome have not yet been fully elucidated. Here, we summarized the characteristics of tissue RAAS expressions in human atherosclerotic lesions and assessed their therapeutic relevance in the prevention of atherosclerotic cardiovascular diseases.

Targeted chemotherapy, the medical ecosystem, and the future of American health care.

PubMed

Gillick, Muriel R

2014-01-01

In light of the difficulties experienced by the pharmaceutical industry in developing important new drugs, the rapid design and introduction of the targeted chemotherapeutic agent, crizotinib, is a significant achievement. Understanding the roles of the patient, the physician, the regulator (FDA), health insurance companies, and the manufacturer (Pfizer) in the development of this drug can shed light on the prospects for future drugs and on the workings of the complicated health-care ecosystem. Patients were eager for an effective drug against lung cancer with minimal toxicity but were reluctant to enroll in clinical trials. Oncologists were enthusiastic about the new drug but have a financial incentive favoring intravenous medicines over oral agents. The FDA was under pressure to approve new drugs quickly. The drug manufacturer modified its corporate structure and developed collaborations with academics and international partners, but was pressured by stockholders to maximize short-term profitability. Insurance companies balked at the price of the drug and used tiered pricing to limit their costs. The successful design, development, and diffusion of crizotinib may signal a new departure for the pharmaceutical industry, but whether such successes are replicated in the future will depend on the delicately balanced ecosystem that constitutes American health care.

Wild Blueberries (Vaccinium myrtillus) Alleviate Inflammation and Hypertension Associated with Developing Obesity in Mice Fed with a High-Fat Diet

PubMed Central

Mykkänen, Otto T.; Huotari, Anne; Herzig, Karl-Heinz; Dunlop, Thomas W.; Mykkänen, Hannu; Kirjavainen, Pirkka V.

2014-01-01

Background Low-grade metabolic inflammation and hypertension are primary mechanisms involved in obesity-associated adverse health effects. Berries, especially Nordic wild blueberries (hereafter referred to as bilberries), represent an important source of dietary anthocyanins, a group of polyphenols with potential beneficial effects to combat obesity-associated metabolic disturbances. Methods The effects of 5% or 10% (w/w) of whole bilberries (BB) were studied on the development of obesity and its metabolic disturbances in C57BL mice fed with a high-fat diet (HFD) for three months. Cytokines, inflammatory cells, systolic blood pressure, glucose tolerance, insulin sensitivity, weight gain, body fat, food consumption and energy metabolism were assessed. Results Bilberries ameliorated type 1 pro-inflammatory responsiveness induced by HFD. This was indicated by the altered cytokine profile and the reduced prevalence of interferon gamma -producing T-cells, in particular T helper type 1 cells. Bilberries also prevented the progression of obesity associated long term increase in systolic blood pressure in mice. Conclusions Bilberries reduce the development of systemic inflammation and prevent the progression of chronic hypertension, thus supporting their potential role in alleviating the adverse health effects associated with developing obesity. PMID:25501421

Influence of high-frequency ambient pressure pumping on carbon dioxide efflux from soil

Treesearch

Eugene S. Takle; William J. Massman; James R. Brandle; R. A. Schmidt; Xinhua Zhou; Irina V. Litvina; Rick Garcia; Geoffrey Doyle; Charles W. Rice

2004-01-01

We report measurements at 2Hz of pressure fluctuations at and beneath the soil in an agricultural field with dry soil and no vegetation. The objective of our study was to examine the possible role of pressure fluctuations produced by fluctuations in ambient wind on the efflux of CO2 at the soil surface.We observed that pressure fluctuations penetrate to 50 cm in the...

Effects of high NaCl diet on arterial pressure in Sprague-Dawley rats with hepatic and sinoaortic denervation.

PubMed

Gao, Shuang; Tanaka, Kunihiko; Gotoh, Taro M; Morita, Hironobu

2005-08-01

The Na(+) receptor that exists in the hepatoportal region plays an important role in postprandial natriuresis and the regulation of Na(+) balance during NaCl load. Thus it would be considered that a dysfunction of the hepatic Na(+) receptor might result in the elevation of arterial pressure under a condition of high NaCl diet. To elucidate this hypothesis, arterial pressure was continuously measured during three weeks of high NaCl diet (8% NaCl) in four groups of rats: (i) intact rats, (ii) rats with hepatic denervation (HD), (iii) rats with sinoaortic denervation (SAD), and (iv) rats with SAD+HD. During a 1-week normal NaCl diet period, there was no difference in arterial pressure among the four groups. A high NaCl diet had no influence on arterial pressure in intact or HD rats; however, it significantly increased by 11 +/- 3 mmHg in SAD rats. The addition of HD to SAD had no synergistic effect on arterial pressure; i.e., in SAD+HD rats, mean arterial pressure increased by 13 +/- 1 mmHg. In conclusion, sinoaortic baroreceptor, but not hepatic Na(+) receptor, has a significant role in the long-term regulation of arterial pressure on a high NaCl diet.

Susceptibility to social pressure following ventromedial prefrontal cortex damage

PubMed Central

Rusch, Michelle L.; Dawson, Jeffrey D.; Rizzo, Matthew; Anderson, Steven W.

2015-01-01

Social pressure influences human behavior including risk taking, but the psychological and neural underpinnings of this process are not well understood. We used the human lesion method to probe the role of ventromedial prefrontal cortex (vmPFC) in resisting adverse social pressure in the presence of risk. Thirty-seven participants (11 with vmPFC damage, 12 with brain damage outside the vmPFC and 14 without brain damage) were tested in driving simulator scenarios requiring left-turn decisions across oncoming traffic with varying time gaps between the oncoming vehicles. Social pressure was applied by a virtual driver who honked aggressively from behind. Participants with vmPFC damage were more likely to select smaller and potentially unsafe gaps under social pressure, while gap selection by the comparison groups did not change under social pressure. Participants with vmPFC damage also showed prolonged elevated skin conductance responses (SCR) under social pressure. Comparison groups showed similar initial elevated SCR, which then declined prior to making left-turn decisions. The findings suggest that the vmPFC plays an important role in resisting explicit and immediately present social pressure with potentially negative consequences. The vmPFC appears to contribute to the regulation of emotional responses and the modulation of decision making to optimize long-term outcomes. PMID:25816815

Electrical conductivity measurement of granulite under mid- to lower crustal pressure-temperature conditions

NASA Astrophysics Data System (ADS)

Fuji-ta, K.; Katsura, T.; Tainosho, Y.

2004-04-01

We have developed a technique to measure electrical conductivity of crustal rocks with relatively low conductivity and complicated mineral components in order to compare with results given by magneto-telluric (MT) measurements. A granulite from Hidaka metamorphic belt (HMB) in Hokkaido, Japan at high temperature and pressure conditions was obtained. The granulite sample was ground and sintered under the conditions similar to those of mid- to lower crust. We have observed smooth and reversible change of conductivity with temperature up to about 900 K at 1 GPa. The results were consistent with the electrical conductivity structures suggested by the MT data analysis. Considering pore fluid conduction mechanism or the role of accessory minerals in the rock, the mechanisms of electrical conductivity paths in dry or basic rocks should be reconsidered.

Monitoring Progress and Adherence with Positive Airway Pressure Therapy for Obstructive Sleep Apnea: The Roles of Telemedicine and Mobile Health Applications.

PubMed

Hwang, Dennis

2016-06-01

Technology is changing the way health care is delivered and how patients are approaching their own health. Given the challenge within sleep medicine of optimizing adherence to continuous positive airway pressure (CPAP) therapy in patients with obstructive sleep apnea (OSA), implementation of telemedicine-based mechanisms is a critical component toward developing a comprehensive and cost-effective solution for OSA management. Key elements include the use of electronic messaging, remote monitoring, automated care mechanisms, and patient self-management platforms. Current practical sleep-related telemedicine platforms include Web-based educational programs, automated CPAP follow-up platforms that promote self-management, and peer-based patient-driven Internet support forums. Copyright © 2016 Elsevier Inc. All rights reserved.

Effect of cold atmospheric pressure He-plasma jet on DNA change and mutation

NASA Astrophysics Data System (ADS)

Yaopromsiri, C.; Yu, L. D.; Sarapirom, S.; Thopan, P.; Boonyawan, D.

2015-12-01

Cold atmospheric pressure plasma jet (CAPPJ) effect on DNA change was studied for assessment of its safety. The experiment utilized a home-developed CAPPJ using 100% helium to directly treat naked DNA plasmid pGFP (plasmid green fluorescent protein). A traversal electric field was applied to separate the plasma components and both dry and wet sample conditions were adopted to investigate various factor roles in changing DNA. Plasma species were measured by using optical emission spectroscopy. DNA topological form change was analyzed by gel electrophoresis. The plasma jet treated DNA was transferred into bacterial Escherichia coli cells for observing mutation. The results show that the He-CAPPJ could break DNA strands due to actions from charge, radicals and neutrals and potentially cause genetic modification of living cells.

Acceleration and heating of two-fluid solar wind by Alfven waves

NASA Technical Reports Server (NTRS)

Sandbaek, Ornulf; Leer, Egil

1994-01-01

Earlier model studies of solar wind driven by thermal pressure and Alfven waves have shown that wave amplitudes of 20-30 km/s at the coronal base are sufficient to accelerate the flow to the high speeds observed in quasi-steady streams emanating from large coronal holes. We focus on the energy balance in the proton gas and show that heat conduction from the region where the waves are dissipated may play an important role in determining the proton temperature at the orbit of Earth. In models with 'classical' heat conduction we find a correlation between high flow speed, high proton temperature, and low electron temperature at 1 AU. The effect of wave heating on the development of anisotropies in the solar wind proton gas pressure is also investigated in this study.

Advances in understanding the renin-angiotensin-aldosterone system (RAAS) in blood pressure control and recent pivotal trials of RAAS blockade in heart failure and diabetic nephropathy

PubMed Central

Ghazi, Lama; Drawz, Paul

2017-01-01

The renin-angiotensin-aldosterone system (RAAS) plays a fundamental role in the physiology of blood pressure control and the pathophysiology of hypertension (HTN) with effects on vascular tone, sodium retention, oxidative stress, fibrosis, sympathetic tone, and inflammation. Fortunately, RAAS blocking agents have been available to treat HTN since the 1970s and newer medications are being developed. In this review, we will (1) examine new anti-hypertensive medications affecting the RAAS, (2) evaluate recent studies that help provide a better understanding of which patients may be more likely to benefit from RAAS blockade, and (3) review three recent pivotal randomized trials that involve newer RAAS blocking agents and inform clinical practice. PMID:28413612

Advances in understanding the renin-angiotensin-aldosterone system (RAAS) in blood pressure control and recent pivotal trials of RAAS blockade in heart failure and diabetic nephropathy.

PubMed

Ghazi, Lama; Drawz, Paul

2017-01-01

The renin-angiotensin-aldosterone system (RAAS) plays a fundamental role in the physiology of blood pressure control and the pathophysiology of hypertension (HTN) with effects on vascular tone, sodium retention, oxidative stress, fibrosis, sympathetic tone, and inflammation. Fortunately, RAAS blocking agents have been available to treat HTN since the 1970s and newer medications are being developed. In this review, we will (1) examine new anti-hypertensive medications affecting the RAAS, (2) evaluate recent studies that help provide a better understanding of which patients may be more likely to benefit from RAAS blockade, and (3) review three recent pivotal randomized trials that involve newer RAAS blocking agents and inform clinical practice.

Early Implementation of Continuous Renal Replacement Therapy Optimizes Casualty Evacuation for Combat-Related Acute Kidney Injury

DTIC Science & Technology

2013-08-01

were Acute Kidney Injury Network (AKIN) 3 and all developed critical hyperkalemia (mean [SD], peak K+ 6.4 [0.4]). The peak plasma creatinine ranged...related acid-base disorders, severe hyperkalemia , and metabolic disorders became apparent. Based on the mounting pressure and internal performance im...with severe hyperkalemia was the most common indication for renal replacement. Validation for critical care evacuation to the Role IV facility mandated a

Palpation Simulator of Beating Aorta for Cardiovascular Surgery Training

NASA Astrophysics Data System (ADS)

Yamamoto, Yasuhiro; Nakao, Megumi; Kuroda, Tomohiro; Oyama, Hiroshi; Komori, Masaru; Matsuda, Tetsuya; Sakaguchi, Genichi; Komeda, Masashi; Takahashi, Takashi

In field of cardiovascular surgeries, palpation of aorta plays important roles in decision of surgical site.This paper develops palpation simulator of aorta based on a finite element based physical model.The proposed model calculates soft tissue deformation according to the affection of inner pressure and the operation of a surgeon.The proposed method is implemented on a prototype with dual PHANToM device.Experimental results confirmed our model achieves real time simulation of the surgical palpation.

The role of the "Healthy Weight" discourse in body image and eating concerns: An extension of sociocultural theory.

PubMed

Rodgers, Rachel F

2016-08-01

Sociocultural models of body image and eating concerns have highlighted the role of the social discourse in promoting the pursuit of the thin-ideal. Recently, another weight-focused social discourse has gained ground, focused on the goal of maintaining body weight within the boundaries of a weight-range defined as "Healthy." This discourse is somewhat different to the promotion of the thin-ideal; however, it might also be implicated in the development of body image and eating concerns. The present study aimed to extend sociocultural theories of the development of body image and eating concerns by (1) proposing a theoretical model accounting for pressure to maintain a "Healthy Weight", and (2) reviewing the existing evidence for the pathways included in this model. In the proposed model, pressure to maintain a Healthy Weight leads to the internalization of anti-fat attitudes and the need to control weight as well as beliefs in the controllability of weight through diet and exercise. These beliefs may then lead to body preoccupation and disordered eating. The extant literature provides initial support for these relationships; however, empirical testing of this model is necessary to determine its usefulness as an explanatory model and in providing intervention targets for future prevention and intervention efforts. Copyright © 2016 Elsevier Ltd. All rights reserved.

Separating the roles of nitrogen and oxygen in high pressure-induced blood-borne microparticle elevations, neutrophil activation, and vascular injury in mice.

PubMed

Yang, Ming; Bhopale, Veena M; Thom, Stephen R

2015-08-01

An elevation in levels of circulating microparticles (MPs) due to high air pressure exposure and the associated inflammatory changes and vascular injury that occur with it may be due to oxidative stress. We hypothesized that these responses arise due to elevated partial pressures of N2 and not because of high-pressure O2. A comparison was made among high-pressure air, normoxic high-pressure N2, and high-pressure O2 in causing an elevation in circulating annexin V-positive MPs, neutrophil activation, and vascular injury by assessing the leakage of high-molecular-weight dextran in a murine model. After mice were exposed for 2 h to 790 kPa air, there were over 3-fold elevations in total circulating MPs as well as subgroups bearing Ly6G, CD41, Ter119, CD31, and CD142 surface proteins-evidence of neutrophil activation; platelet-neutrophil interaction; and vascular injury to brain, omentum, psoas, and skeletal muscles. Similar changes were found in mice exposed to high-pressure N2 using a gas mixture so that O2 partial pressure was the same as that of ambient air, whereas none of these changes occurred after exposures to 166 kPa O2, the same partial pressure that occurs during high-pressure air exposures. We conclude that N2 plays a central role in intra- and perivascular changes associated with exposure to high air pressure and that these responses appear to be a novel form of oxidative stress. Copyright © 2015 the American Physiological Society.

Modelling C₃ photosynthesis from the chloroplast to the ecosystem.

PubMed

Bernacchi, Carl J; Bagley, Justin E; Serbin, Shawn P; Ruiz-Vera, Ursula M; Rosenthal, David M; Vanloocke, Andy

2013-09-01

Globally, photosynthesis accounts for the largest flux of CO₂ from the atmosphere into ecosystems and is the driving process for terrestrial ecosystem function. The importance of accurate predictions of photosynthesis over a range of plant growth conditions led to the development of a C₃ photosynthesis model by Farquhar, von Caemmerer & Berry that has become increasingly important as society places greater pressures on vegetation. The photosynthesis model has played a major role in defining the path towards scientific understanding of photosynthetic carbon uptake and the role of photosynthesis on regulating the earth's climate and biogeochemical systems. In this review, we summarize the photosynthesis model, including its continued development and applications. We also review the implications these developments have on quantifying photosynthesis at a wide range of spatial and temporal scales, and discuss the model's role in determining photosynthetic responses to changes in environmental conditions. Finally, the review includes a discussion of the larger-scale modelling and remote-sensing applications that rely on the leaf photosynthesis model and are likely to open new scientific avenues to address the increasing challenges to plant productivity over the next century. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.

The ischemic liver cirrhosis theory and its clinical implications.

PubMed

Mancuso, Andrea

2016-09-01

The canonical pathway theory of cirrhosis addresses inflammation as the main driver of hepatic fibrogenesis in hepatitis, so needing a further hypothesis for etiologies missing inflammation, for which parenchymal extinction is postulated. The present paper reports an alternative hypothesis suggesting a central role of micro-vascular ischemia in fibrogenesis and cirrhosis development, whatever is the aetiology of liver chronic injury. In fact, since chronic liver injury could finally result in endothelial damage and micro-vascular thrombosis, leading to a trigger of inappropriate hepatocyte proliferation and fibrosis, finally cirrhosis development could arise from chronic micro-vascular ischemia. Recently, some important confirmation of this hypothesis has been reported. In fact, in a murine experimental model of congestive hepatopathy, it was found that chronic hepatic congestion leads to sinusoidal thrombosis and strain, which in turn promote hepatic fibrosis. Furthermore, a study on a murine model of cirrhosis reported enoxaparin to reduce hepatic vascular resistance and portal pressure by having a protective role against fibrogenesis. In conclusion, the hypothesis giving a central role of micro-vascular ischemia in fibrogenesis and cirrhosis development could change the clinical scenario of chronic liver disease and have several main implications on management of various liver disease. Copyright © 2016 Elsevier Ltd. All rights reserved.

The Small GTPase MoSec4 Is Involved in Vegetative Development and Pathogenicity by Regulating the Extracellular Protein Secretion in Magnaporthe oryzae

PubMed Central

Zheng, Huakun; Chen, Simiao; Chen, Xiaofeng; Liu, Shuyan; Dang, Xie; Yang, Chengdong; Giraldo, Martha C.; Oliveira-Garcia, Ely; Zhou, Jie; Wang, Zonghua; Valent, Barbara

2016-01-01

The Rab GTPase proteins play important roles in the membrane trafficking, and consequently protein secretion and development of eukaryotic organisms. However, little is known about the function of Rab GTPases in Magnaporthe oryzae. To further explore the function of Rab GTPases, we deleted the ortholog of the yeast Sec4p protein in M. oryzae, namely MoSEC4. The ΔMosec4 mutant is defective in polarized growth and conidiation, and it displays decreased appressorium turgor pressure and attenuated pathogenicity. Notably, the biotrophic invasive hyphae produced in rice cells are more bulbous and compressed in the ΔMosec4 mutant. Further studies showed that deletion of the MoSEC4 gene resulted in decreased secretion of extracellular enzymes and mislocalization of the cytoplasmic effector PWL2-mCherry-NLS. In accordance with a role in secretion, the GFP-MoSec4 fusion protein mainly accumulates at tips of growing vegetative hyphae. Our results suggest that the MoSec4 protein plays important roles in the secretion of extracellular proteins and consequently hyphal development and pathogenicity in the rice blast fungus. PMID:27729922

Human Factors Considerations for Safe Recovery from Faults In Flight Control Systems

NASA Technical Reports Server (NTRS)

Pritchett, Amy; Belcastro, C. M. (Technical Monitor)

2003-01-01

It is now possible - and important - to develop systems to help resolve Flight Control System (FCS) faults. From a human factors viewpoint, it is imperative that these systems take on roles, and provide functions, that are the most supportive to the pilot, given the stress, time pressure and workload they may experience following a FCS fault. FCS fault recovery systems may provide several different functions, including alerting, control assistance, and decision aiding. The biggest human factors questions are in the role suitable for the technology, and its specific functioning to achieve that role. Specifically, for these systems to be effective, they must meet the fundamental requirements that (1) they alert pilots to problems early enough that the pilot can reasonably resolve the fault and regain control of the aircraft and that (2) if the aircraft s handling qualities are severely degraded the HMS provide the appropriate stability augmentation to help the pilot stabilize and control the aircraft. This project undertook several research steps to develop such systems, focusing on the capabilities of pilots and on realistically attainable technologies. The ability to estimate which functions are the most valuable will help steer system development in the directions that can establish the highest safety levels.

In-situ Raman spectroscopy and high-speed photography of a shocked triaminotrinitrobenzene based explosive

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

Saint-Amans, C.; Hébert, P., E-mail: philippe.hebert@cea.fr; Doucet, M.

2015-01-14

We have developed a single-shot Raman spectroscopy experiment to study at the molecular level the initiation mechanisms that can lead to sustained detonation of a triaminotrinitrobenzene-based explosive. Shocks up to 30 GPa were generated using a two-stage laser-driven flyer plate generator. The samples were confined by an optical window and shock pressure was maintained for at least 30 ns. Photon Doppler Velocimetry measurements were performed at the explosive/window interface to determine the shock pressure profile. Raman spectra were recorded as a function of shock pressure and the shifts of the principal modes were compared to static high-pressure measurements performed in a diamondmore » anvil cell. Our shock data indicate the role of temperature effects. Our Raman spectra also show a progressive extinction of the signal which disappears around 9 GPa. High-speed photography images reveal a simultaneous progressive darkening of the sample surface up to total opacity at 9 GPa. Reflectivity measurements under shock compression show that this opacity is due to a broadening of the absorption spectrum over the entire visible region.« less

Eating Behaviours of Preadolescent Children over Time: Stability, Continuity and the Moderating Role of Perceived Parental Feeding Practices

PubMed Central

Houldcroft, Laura; Farrow, Claire; Haycraft, Emma

2016-01-01

The links between childhood eating behaviours and parental feeding practices are well-established in younger children, but there is a lack of research examining these variables in a preadolescent age group, particularly from the child’s perspective, and longitudinally. This study firstly aimed to examine the continuity and stability of preadolescent perceptions of their parents’ controlling feeding practices (pressure to eat and restriction) over a 12 month period. The second aim was to explore if perceptions of parental feeding practices moderated the relationship between preadolescents’ eating behaviours longitudinally. Two hundred and twenty nine preadolescents (mean age at recruitment 8.73 years) completed questionnaires assessing their eating behaviours and their perceptions of parental feeding practices at two time points, 12 months apart (T1 and T2). Preadolescents’ perceptions of their parental feeding practices remained stable. Perceptions of restriction and pressure to eat were continuous. Perceptions of parental pressure to eat and restriction significantly moderated the relationships between eating behaviours at T1 and T2. The findings from this study suggest that in a preadolescent population, perceptions of parental pressure to eat and restriction of food may exacerbate the development of problematic eating behaviours. PMID:27104552

Eating Behaviours of Preadolescent Children over Time: Stability, Continuity and the Moderating Role of Perceived Parental Feeding Practices.

PubMed

Houldcroft, Laura; Farrow, Claire; Haycraft, Emma

2016-04-20

The links between childhood eating behaviours and parental feeding practices are well-established in younger children, but there is a lack of research examining these variables in a preadolescent age group, particularly from the child's perspective, and longitudinally. This study firstly aimed to examine the continuity and stability of preadolescent perceptions of their parents' controlling feeding practices (pressure to eat and restriction) over a 12 month period. The second aim was to explore if perceptions of parental feeding practices moderated the relationship between preadolescents' eating behaviours longitudinally. Two hundred and twenty nine preadolescents (mean age at recruitment 8.73 years) completed questionnaires assessing their eating behaviours and their perceptions of parental feeding practices at two time points, 12 months apart (T1 and T2). Preadolescents' perceptions of their parental feeding practices remained stable. Perceptions of restriction and pressure to eat were continuous. Perceptions of parental pressure to eat and restriction significantly moderated the relationships between eating behaviours at T1 and T2. The findings from this study suggest that in a preadolescent population, perceptions of parental pressure to eat and restriction of food may exacerbate the development of problematic eating behaviours.

The role of the reactor wall in hydrothermal biomass conversions.

PubMed

Fábos, Viktória; Yuen, Alexander K L; Masters, Anthony F; Maschmeyer, Thomas

2012-11-01

The processing of renewable feedstocks to platform chemicals and, to a lesser degree, fuels is a key part of sustainable development. In particular, the combination of lignocellulosic biomass with hydrothermal upgrading (HTU), using high temperature and pressure water (HTPW), is experiencing a renaissance. One of the many steps in this complicated process is the in-situ hydrogenation of intermediate compounds. As formic acid and related low-molecular-weight oxygenates are among the species generated, it is conceivable that they act as a hydrogen source. Such hydrogenations have been suggested to be catalyzed by water, by bases like NaOH, and/or to involve "reactive/nascent hydrogen". To achieve the temperatures and pressures required for HTU, it is necessary to conduct the reactions in high-pressure vessels. Metals are typical components of their walls and/or internal fittings. Here, using cyclohexanone as a model compound for more complex biomass-derived molecules, iron in the wall of high-pressure stainless steel reactors is shown to be responsible for the hydrogenation of ketones with low-molecular-weight oxygenates acting as a hydrogen source in combination with water. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The control of microvascular permeability and blood pressure by neutral endopeptidase.

PubMed

Lu, B; Figini, M; Emanueli, C; Geppetti, P; Grady, E F; Gerard, N P; Ansell, J; Payan, D G; Gerard, C; Bunnett, N

1997-08-01

Plasma extravasation from postcapillary venules is one of the earliest steps of inflammation. Substance P (SP) and bradykinin (BK) mediate extravasation and cause hypotension. The cell-surface enzyme neutral endopeptidase (NEP) inactivates both peptides. Thus, absence of NEP may predispose development of inflammation and hypotension. We examined these possibilities in mice in which the NEP gene was deleted by homologous recombination. There was widespread basal plasma extravasation in postcapillary venular endothelia in NEP-/- mice, which was reversed by recombinant NEP and antagonists of SP (NK1) and BK (B2) receptors. Mean arterial blood pressure was 20% lower in NEP-/- animals, but this was unaffected by reintroduction of recombinant NEP and the kinin receptor antagonists. The hypotension was also independent of nitric oxide (NO), because NEP-/- mice treated with a NO synthase inhibitor remained hypotensive relative to the wild type. Thus, NEP has important roles in regulating basal microvascular permeability by degrading SP and BK, and may regulate blood pressure set point through a mechanism that is independent of SP, BK and NO. The use of NEP antagonists as candidate drugs in cardiovascular disease is suggested by the blood pressure data reported herein.

Cardiac-specific overexpression of aldehyde dehydrogenase 2 exacerbates cardiac remodeling in response to pressure overload.

PubMed

Dassanayaka, Sujith; Zheng, Yuting; Gibb, Andrew A; Cummins, Timothy D; McNally, Lindsey A; Brittian, Kenneth R; Jagatheesan, Ganapathy; Audam, Timothy N; Long, Bethany W; Brainard, Robert E; Jones, Steven P; Hill, Bradford G

2018-06-01

Pathological cardiac remodeling during heart failure is associated with higher levels of lipid peroxidation products and lower abundance of several aldehyde detoxification enzymes, including aldehyde dehydrogenase 2 (ALDH2). An emerging idea that could explain these findings concerns the role of electrophilic species in redox signaling, which may be important for adaptive responses to stress or injury. The purpose of this study was to determine whether genetically increasing ALDH2 activity affects pressure overload-induced cardiac dysfunction. Mice subjected to transverse aortic constriction (TAC) for 12 weeks developed myocardial hypertrophy and cardiac dysfunction, which were associated with diminished ALDH2 expression and activity. Cardiac-specific expression of the human ALDH2 gene in mice augmented myocardial ALDH2 activity but did not improve cardiac function in response to pressure overload. After 12 weeks of TAC, ALDH2 transgenic mice had larger hearts than their wild-type littermates and lower capillary density. These findings show that overexpression of ALDH2 augments the hypertrophic response to pressure overload and imply that downregulation of ALDH2 may be an adaptive response to certain forms of cardiac pathology. Copyright © 2018. Published by Elsevier B.V.

Magnolol Administration in Normotensive Young Spontaneously Hypertensive Rats Postpones the Development of Hypertension: Role of Increased PPAR Gamma, Reduced TRB3 and Resultant Alleviative Vascular Insulin Resistance

PubMed Central

Fu, Feng; Zhang, Wei; Su, Feifei; Liu, Fange; Ji, Lele; Gao, Feng; Su, Hui; Sun, Xin; Zhang, Haifeng

2015-01-01

Patients with prehypertension are more likely to progress to manifest hypertension than those with optimal or normal blood pressure. However, the mechanisms underlying the development from prehypertension to hypertension still remain largely elusive and the drugs for antihypertensive treatment in prehypertension are absent. Here we determined the effects of magnolol (MAG) on blood pressure and aortic vasodilatation to insulin, and investigated the underlying mechanisms. Four-week-old male spontaneous hypertensive rats (SHR) and age-matched normotensive Wistar-Kyoto (WKY) control rats were used. Our results shown that treatment of young SHRs with MAG (100 mg/kg/day, o.g.) for 3 weeks decreased blood pressure, improved insulin-induced aorta vasodilation, restored Akt and eNOS activation stimulated by insulin, and increased PPARγ and decreased TRB3 expressions. In cultured human umbilical vein endothelial cells (HUVECs), MAG incubation increased PPARγ, decreased TRB3 expressions, and restored insulin-induced phosphorylated Akt and eNOS levels and NO production, which was blocked by both PPARγ antagonist and siRNA targeting PPARγ. Improved insulin signaling in HUVECs by MAG was abolished by upregulating TRB3 expression. In conclusion, treatment of young SHRs with MAG beginning at the prehypertensive stage decreases blood pressure via improving vascular insulin resistance that is at least partly attributable to upregulated PPARγ, downregulated TRB3 and consequently increased Akt and eNOS activations in blood vessels in SHRs. PMID:25793876

UKPDS 59: hyperglycemia and other potentially modifiable risk factors for peripheral vascular disease in type 2 diabetes.

PubMed

Adler, Amanda I; Stevens, Richard J; Neil, Andrew; Stratton, Irene M; Boulton, Andrew J M; Holman, Rury R

2002-05-01

To determine the role of hyperglycemia in prospective analyses of peripheral vascular disease (PVD) in type 2 diabetes, taking into account other potential risk factors. Potential risk factors for the development of PVD were examined in 3,834 of 5,102 individuals enrolled in the U.K. Prospective Diabetes Study (UKPDS) without PVD at diagnosis of diabetes, followed for 6 years, and for whom relevant data were available. PVD was defined as two of the following: ankle-arm blood pressure index < 0.8, absence of both dorsalis pedis and posterior tibial pulses to palpation in one or both legs, and intermittent claudication. Logistic regression was used to estimate the association between potential risk factors measured 3-4 months after diagnosis of diabetes and incident PVD. The prevalence of PVD at 3-year intervals to 18 years was determined. Hyperglycemia, assessed as HbA(1c), was associated with an increased risk for incident PVD, independent of other risk factors including age, increased systolic blood pressure, reduced HDL cholesterol, smoking, prior cardiovascular disease, peripheral sensory neuropathy, and retinopathy. Each 1% increase in HbA(1c) was associated with a 28% increased risk of PVD (95% CI 12-46), and each 10-mmHg increase in systolic blood pressure with a 25% increase in risk (95% CI 10-43). Hyperglycemia, as well as smoking, dyslipidemia, and blood pressure are potentially modifiable risk factors for the development of PVD.

Experimental Analysis of the Role of Fluid Transport Properties in Fluid-Induced Fracture Initiation and Propagation

NASA Astrophysics Data System (ADS)

Boutt, D.; McPherson, B. J.; Cook, B. K.; Goodwin, L. B.; Williams, J. R.; Lee, M. Y.; Patteson, R.

2003-12-01

It is well known that pore fluid pressure fundamentally influences a rock's mechanical response to stress. However, most measures of the mechanical behavior of rock (e.g. shear strength, Young's modulus) do not incorporate, either explicitly or implicitly, pore fluid pressure or transport properties of rock. Current empirical and theoretical criteria that define the amount of stress a given body of rock can support before fracturing also lack a direct connection between fluid transport and mechanical properties. Our research goal is to use laboratory experimental results to elucidate correlations between rock transport properties and fracture behavior under idealized loading conditions. In strongly coupled fluid-solid systems the evolution of the solid framework is influenced by the fluid and vice versa. These couplings often result in changes of the bulk material properties (i.e. permeability and failure strength) with respect to the fluid's ability to move through the solid and the solids ability to transmit momentum. Feedbacks between fluid and solid framework ultimately play key roles in understanding the spatial and temporal evolution of the coupled fluid-solid system. Discretely coupled models of fluid and solid mechanics were developed a priori to design an experimental approach for testing the role of fluid transport parameters in rock fracture. The experimental approach consists of first loading a fluid saturated cylindrical rock specimen under hydrostatic conditions and then applying a differential stress such that the maximum stress is perpendicular to the cylinder long axis. At the beginning of the test the minimum stress and the fluid pressure are dropped at the same time such that the resulting difference in the initial fluid pressure and the final fluid pressure is greater than the final minimum stress. These loading conditions should produce a fluid driven tensile fracture that is perpendicular to the cylinder long axis. Initial analyses using numerical simulations with similar boundary conditions suggest that resulting fracture propagation rates and fracture spacing are controlled by the rocks hydraulic diffusivity. Modeled rocks with higher permeability had fractures with larger apertures, more localized deformation, and greater fracture spacing. Intuitively, these results are consistent with permeability controlling the time required for pressure to come to equilibrium with the new boundary conditions. Finally, more general goals of this research include using these core-scale experimental data and discrete simulation results to calibrate larger-scale, more traditional continuum models of geologic deformation.

CXCR6 deficiency attenuates pressure overload-induced monocytes migration and cardiac fibrosis through downregulating TNF-α-dependent MMP9 pathway

PubMed Central

Wang, Jia-Hong; Su, Feng; Wang, Shijun; Lu, Xian-Cheng; Zhang, Shao-Heng; Chen, De; Chen, Nan-Nan; Zhong, Jing-Quan

2014-01-01

An immerging role of TNF-α in collagen synthesis and cardiac fibrosis implies the significance of TNF-α production in the development of myocardial remodeling. Our previous study showed a reduction of TNF-α and attenuated cardiac remodeling in CXCR6 knockout (KO) mice after ischemia/reperfusion injury. However, the potential mechanism of TNF-α-mediated cardiac fibrosis with pressure overload has not been well elucidated. In the present study, we aim to investigate the role of CXCR6 in TNF-α release and myocardial remodeling in response to pressure overload. Pressure overload was performed by constriction of transverse aorta (TAC) surgery on CXCR6 KO mice and C57 wild-type (WT) counterparts. At 6 weeks after TAC, cardiac remodeling was assessed by echocardiography, cardiac TNF-α release and its type I receptor (TNFRI), were detected by ELISA and western blot, collagen genes Col1a1 (type I) and Col3a1 (type III) were examined by real-time PCR. Compared with CXCR6 WT mice, CXCR6 KO mice exhibited less cardiac dysfunction, reduced expression of TNFRI, Col1a1 and Col3a. In vitro, we confirmed that CXCR6 deficiency led to reduced homing and infiltration of CD11b+ monocytes, which contributed to attenuated TNF-α release in myocardium. Furthermore, TNFRI antagonist pretreatment blocked AT1 receptor signaling and NOX4 expression, reduced collagen synthesis, and blunted the activity of MMP9 in CXCR6 WT mice after TAC, but these were not observed in CXCR6 KO mice. In the present work, we propose a mechanism that CXCR6 is essential for pressure overload-mediated myocardial recruitment of monocytes, which contributes to cardiac fibrosis through TNF-α-dependent MMP9 activation and collagen synthesis. PMID:25400729

CXCR6 deficiency attenuates pressure overload-induced monocytes migration and cardiac fibrosis through downregulating TNF-α-dependent MMP9 pathway.

PubMed

Wang, Jia-Hong; Su, Feng; Wang, Shijun; Lu, Xian-Cheng; Zhang, Shao-Heng; Chen, De; Chen, Nan-Nan; Zhong, Jing-Quan

2014-01-01

An immerging role of TNF-α in collagen synthesis and cardiac fibrosis implies the significance of TNF-α production in the development of myocardial remodeling. Our previous study showed a reduction of TNF-α and attenuated cardiac remodeling in CXCR6 knockout (KO) mice after ischemia/reperfusion injury. However, the potential mechanism of TNF-α-mediated cardiac fibrosis with pressure overload has not been well elucidated. In the present study, we aim to investigate the role of CXCR6 in TNF-α release and myocardial remodeling in response to pressure overload. Pressure overload was performed by constriction of transverse aorta (TAC) surgery on CXCR6 KO mice and C57 wild-type (WT) counterparts. At 6 weeks after TAC, cardiac remodeling was assessed by echocardiography, cardiac TNF-α release and its type I receptor (TNFRI), were detected by ELISA and western blot, collagen genes Col1a1 (type I) and Col3a1 (type III) were examined by real-time PCR. Compared with CXCR6 WT mice, CXCR6 KO mice exhibited less cardiac dysfunction, reduced expression of TNFRI, Col1a1 and Col3a. In vitro, we confirmed that CXCR6 deficiency led to reduced homing and infiltration of CD11b(+) monocytes, which contributed to attenuated TNF-α release in myocardium. Furthermore, TNFRI antagonist pretreatment blocked AT1 receptor signaling and NOX4 expression, reduced collagen synthesis, and blunted the activity of MMP9 in CXCR6 WT mice after TAC, but these were not observed in CXCR6 KO mice. In the present work, we propose a mechanism that CXCR6 is essential for pressure overload-mediated myocardial recruitment of monocytes, which contributes to cardiac fibrosis through TNF-α-dependent MMP9 activation and collagen synthesis.

Skin friction under pressure. The role of micromechanics

NASA Astrophysics Data System (ADS)

Leyva-Mendivil, Maria F.; Lengiewicz, Jakub; Limbert, Georges

2018-03-01

The role of contact pressure on skin friction has been documented in multiple experimental studies. Skin friction significantly raises in the low-pressure regime as load increases while, after a critical pressure value is reached, the coefficient of friction of skin against an external surface becomes mostly insensitive to contact pressure. However, up to now, no study has elucidated the qualitative and quantitative nature of the interplay between contact pressure, the material and microstructural properties of the skin, the size of an indenting slider and the resulting measured macroscopic coefficient of friction. A mechanistic understanding of these aspects is essential for guiding the rational design of products intended to interact with the skin through optimally-tuned surface and/or microstructural properties. Here, an anatomically-realistic 2D multi-layer finite element model of the skin was embedded within a computational contact homogenisation procedure. The main objective was to investigate the sensitivity of macroscopic skin friction to the parameters discussed above, in addition to the local (i.e. microscopic) coefficient of friction defined at skin asperity level. This was accomplished via the design of a large-scale computational experiment featuring 312 analyses. Results confirmed the potentially major role of finite deformations of skin asperities on the resulting macroscopic friction. This effect was shown to be modulated by the level of contact pressure and relative size of skin surface asperities compared to those of a rigid slider. The numerical study also corroborated experimental observations concerning the existence of two contact pressure regimes where macroscopic friction steeply and non-linearly increases up to a critical value, and then remains approximately constant as pressure increases further. The proposed computational modelling platform offers attractive features which are beyond the reach of current analytical models of skin friction, namely, the ability to accommodate arbitrary kinematics, non-linear constitutive properties and the complex skin microstructure.

Intermittent cardiac overload results in adaptive hypertrophy and provides protection against left ventricular acute pressure overload insult.

PubMed

Moreira-Gonçalves, Daniel; Henriques-Coelho, Tiago; Fonseca, Hélder; Ferreira, Rita; Padrão, Ana Isabel; Santa, Cátia; Vieira, Sara; Silva, Ana Filipa; Amado, Francisco; Leite-Moreira, Adelino; Duarte, José Alberto

2015-09-01

The present study aimed to test whether a chronic intermittent workload could induce an adaptive cardiac phenotype Chronic intermittent workload induced features of adaptive hypertrophy This was paralleled by protection against acute pressure overload insult The heart may adapt favourably to balanced demands, regardless of the nature of the stimuli. The present study aimed to test whether submitting the healthy heart to intermittent and tolerable amounts of workload, independently of its nature, could result in an adaptive cardiac phenotype. Male Wistar rats were subjected to treadmill running (Ex) (n = 20), intermittent cardiac overload with dobutamine (ITO) (2 mg kg(-1) , s.c.; n = 20) or placebo administration (Cont) (n = 20) for 5 days week(-1) for 8 weeks. Animals were then killed for histological and biochemical analysis or subjected to left ventricular haemodynamic evaluation under baseline conditions, in response to isovolumetric contractions and to sustained LV acute pressure overload (35% increase in peak systolic pressure maintained for 2 h). Baseline cardiac function was enhanced only in Ex, whereas the response to isovolumetric heartbeats was improved in both ITO and Ex. By contrast to the Cont group, in which rats developed diastolic dysfunction with sustained acute pressure overload, ITO and Ex showed increased tolerance to this stress test. Both ITO and Ex developed cardiomyocyte hypertrophy without fibrosis, no overexpression of osteopontin-1 or β-myosin heavy chain, and increased expression of sarcoplasmic reticulum Ca(2+) protein. Regarding hypertrophic pathways, ITO and Ex showed activation of the protein kinase B/mammalian target of rapamycin pathway but not calcineurin. Mitochondrial complex IV and V activities were also increased in ITO and Ex. Chronic submission to controlled intermittent cardiac overload, independently of its nature, results in an adaptive cardiac phenotype. Features of the cardiac overload, such as the duration and magnitude of the stimuli, may play a role in the development of an adaptive or maladaptive phenotype. © 2015 The Authors. The Journal of Physiology © 2015 The Physiological Society.

Role of Left Ventricular Diastolic Dysfunction in Predicting Atrial Fibrillation Recurrence after Successful Electrical Cardioversion

PubMed Central

Melduni, Rowlens M.; Cullen, Michael W.

2013-01-01

The role of left ventricular (LV) diastolic dysfunction in predicting atrial fibrillation (AF) recurrence after successful electrical cardioversion is largely unknown. Studies suggest that there may be a link between abnormal LV compliance and the initial development, and recurrence of AF after electrical cardioversion. Although direct-current cardioversion (DCCV) is a well-established and highly effective method to convert AF to sinus rhythm, it offers little else beyond immediate rate control because it does not address the underlying cause of AF. Preservation of sinus rhythm after successful cardioversion still remains a challenge for clinicians. Despite the use of antiarrhythmic drugs and serial cardioversions, the rate of AF recurrence remains high in the first year. Current evidence suggests that diastolic dysfunction, which is associated with atrial volume and pressure overload, may be a mechanism underlying the perpetuating cycle of AF recurrence following successful electrical cardioversion. Diastolic dysfunction is considered to be a defect in the ability of the myofibrils, which have shortened against a load in systole to eject blood into the high-pressure aorta, to rapidly or completely return to their resting length. Consequently, LV filling is impaired and the non-compliant left ventricle is unable to fill at low pressures. As a result, left atrial and pulmonary vein pressure rises, and electrical and structural remodeling of the atrial myocardium ensues, creating a vulnerable substrate for AF. In this article, we review the current evidence highlighting the association of LV diastolic dysfunction with AF recurrence after successful electrical cardioversion and provide an approach to the management of LV diastolic dysfunction to prevent AF recurrence. PMID:23525127

Exploring the boundary between a siphon and barometer in a hypobaric chamber

PubMed Central

Hughes, Stephen; Gurung, Som

2014-01-01

Siphons have been used since ancient times, but exactly how they work is still a matter of debate. In order to elucidate the modus operandi of a siphon, a 1.5 m high siphon was set up in a hypobaric chamber to explore siphon behaviour in a low-pressure environment. When the pressure in the chamber was reduced to about 0.18 atmospheres, a curious waterfall-like feature appeared downstream from the apex of the siphon. A hypothesis is presented to explain the waterfall phenomenon. When the pressure was reduced further the siphon broke into two columns - in effect becoming two back-to-back barometers. This experiment demonstrates the role of atmospheric pressure in explaining the hydrostatic characteristics of a siphon and the role of molecular cohesion in explaining the hydrodynamic aspects. PMID:24751967

Dynamics of an experimental microbial invasion

PubMed Central

Acosta, Francisco; Zamor, Richard M.; Najar, Fares Z.; Roe, Bruce A.; Hambright, K. David

2015-01-01

The ecological dynamics underlying species invasions have been a major focus of research in macroorganisms for the last five decades. However, we still know little about the processes behind invasion by unicellular organisms. To expand our knowledge of microbial invasions, we studied the roles of propagule pressure, nutrient supply, and biotic resistance in the invasion success of a freshwater invasive alga, Prymnesium parvum, using microcosms containing natural freshwater microbial assemblages. Microcosms were subjected to a factorial design with two levels of nutrient-induced diversity and three levels of propagule pressure, and incubated for 7 d, during which P. parvum densities and microbial community composition were tracked. Successful invasion occurred in microcosms receiving high propagule pressure whereas nutrients or community diversity played no role in invasion success. Invaded communities experienced distinctive changes in composition compared with communities where the invasion was unsuccessful. Successfully invaded microbial communities had an increased abundance of fungi and ciliates, and decreased abundances of diatoms and cercozoans. Many of these changes mirrored the microbial community changes detected during a natural P. parvum bloom in the source system. This role of propagule pressure is particularly relevant for P. parvum in the reservoir-dominated southern United States because this species can form large, sustained blooms that can generate intense propagule pressures for downstream sites. Human impact and global climate change are currently causing widespread environmental changes in most southern US freshwater systems that may facilitate P. parvum establishment and, when coupled with strong propagule pressure, could put many more systems at risk for invasion. PMID:26324928

Transient receptor potential vanilloid-3 (TRPV3) activation plays a central role in cardiac fibrosis induced by pressure overload in rats via TGF-β1 pathway.

PubMed

Liu, Yan; Qi, Hanping; E, Mingyao; Shi, Pilong; Zhang, Qianhui; Li, Shuzhi; Wang, Ye; Cao, Yonggang; Chen, Yunping; Ba, Lina; Gao, Jingquan; Huang, Wei; Sun, Hongli

2018-02-01

Cardiac fibrosis is a common pathologic change along with pressure overload. Recent studies indicated that transient receptor potential (TRP) channels played multiple roles in heart. However, the functional role of transient receptor potential vanilloid-3 (TRPV3) in cardiac fibrosis remained unclear. The present study was designed to investigate the relationship between TRPV3 activation and pressure overload-induced cardiac fibrosis. Pressure overload rats were successfully established by abdominal aortic constriction (AAC), and cardiac fibrosis was simulated by 100 nM angiotensin II (Ang II) in neonatal cardiac fibroblasts. Echocardiographic parameters, cardiac fibroblast proliferation, cell cycle, intracellular calcium concentration ([Ca 2+ ] i ), and the protein expressions of collagen I, collagen III, transforming growth factor beta 1 (TGF-β 1 ), cyclin E, and cyclin-dependent kinase 2 (CDK2) were measured. Echocardiographic and histological measurements suggested that the activation of TRPV3 exacerbated the cardiac dysfunction and increased interstitial fibrosis in pressure overload rats. Further results showed that TRPV3 activation upregulated the expressions of collagen I, collagen III, TGF-β 1 , cyclin E, and CDK2 in vivo and in vitro. At the same time, blocking TGF-β 1 pathway could partially reverse the effect of TRPV3 activation. These results suggested that TRPV3 activation exacerbated cardiac fibrosis by promoting cardiac fibroblast proliferation through TGF-β 1 /CDK2/cyclin E pathway in the pressure-overloaded rat hearts.

Modeling Ultra-fast assembly and sintering of gold nanostructures

NASA Astrophysics Data System (ADS)

Lane, J. Matthew D.; Salerno, K. Michael; Grest, Gary S.; Fan, Hongyou

We use fully atomistic simulations to understand the role of extreme pressure in the assembly and sintering of fcc superlattices of alkanethiol-coated gold nanocrystals into larger nanostructures. Recent quasi-isentropic experiments have shown that 1D, 2D and 3D nanostructures can be formed and recovered from dynamic compression experiments on Sandia's Veloce pulsed power accelerator. Here, we describe the role of coating properties, such as ligand length and grafting density, on ligand migration and deformation processes during pressure-driven coalescence of metal nano cores into permanent nanowires, nanosheets and 3D structures. The role of uniaxial vs isotropic pressure and the effects of compression along various superlattice orientations will be discussed. Sandia National Laboratories is a multi-mission laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Improving and assessing vapour pressure estimation methods for organic compounds of atmospheric relevance using a Knudsen Effusion Mass Spectrometer (KEMS)

NASA Astrophysics Data System (ADS)

Booth, A. M.; Topping, D. O.; McFiggans, G. B.; Garforth, A.; Percival, C. J.

2009-12-01

Aerosol particles influence climate directly through the scattering and absorbing radiation and indirectly through their role as cloud condensation nuclei (CCN). Traditionally, models aiming to capture the behaviour of aerosols in the atmosphere have concentrated on the role of inorganic compounds. However, organic components, covering a huge range of chemical and physical properties (Jacobson et.al., 2000), may constitute a significant fraction depending on location (Houghton et.al., 2001). Knowledge of pure component vapour pressures is essential for calculations of gas/particle partitioning. There are many methods of estimating vapour pressures but most of the experimental data collected to date has been for intermediate or high pressure compounds (and often measured at temperatures considerably above ambient) and the proportion of experimental data for low (less than 100Pa) vapour pressure compounds has been very small. Hence the datasets used for developing the estimation methods have reflected this bias in addition to the fact that components studied tend to have one or two functional groups at the most. Thus it is unsurprising that some of the estimation methods can give errors in vapour pressure of several orders of magnitude for multifunctional compounds at ambient temperatures. Knudsen Effusion Mass Spectrometer (KEMS) has been used to measure solid state vapour pressures for multifunctional organic compounds based on dicarboxylic acids (Booth et al 2009). In the atmosphere these compounds are likely to exist in the sub-cooled state so Differential Scanning Calorimetry (DSC) was used to obtain thermochemical data to effect a correction between solid and sub-cooled vapour pressures. The group contribution method of Nanoolal and co-workers (Nanoolal et al., 2008) is one of the best predictive methods in terms of reproducing available low volatility vapour pressure data (barley et al., 2009). The Nanoolal method relies on the use of primary and secondary functional groups and interaction parameters, derived from experimental data, to reliably predict boiling points and vapour pressures. A sensitivity study was undertaken to establish the impact of the new experimentally determined vapour pressures on partitioning models. Jacobson, M.C., et al. Rev Geophys, 38 (2), 267-294, 2000. Houghton et al. Climate Change 2001: The Scientific Basis. Contribution of Working Group 1 to the Third Assessment Report of the IPCC., 881 pp., Cambridge University Press, 2001. Johnson, D. , et al. Atmo. Chem. Phys., Vol. 6, 419-431, 2006 Yu, J. Z., et al. J Atmos Chem. 34, 207-258, 1999 Booth, A.M. et al Atmos. Meas. Tech.,2,355-361, 2009 Nanoolal, Y. et al Fluid Phase Equilibria, 269,117-133., 2008. Barley, M. et al Atmos. Chem. Phys., -,to be submitted.

Role of air on local water retention behavior in the shallow heterogeneous vadose zone

NASA Astrophysics Data System (ADS)

Sakaki, T.; Limsuwat, A.; Illangasekare, T. H.

2009-12-01

In the presence of a subsurface source, air flowing through the unsaturated soil can transport toxic vapor into subsurface structures due to pressure gradients created by, e.g., a pressure drop within the building. Development of dynamic air pathways in the subsurface are largely controlled by the geological heterogeneity and the spatial and temporal distribution of soil moisture. To better understand how these air pathways are developed, it is crucial to know how water is retained in heterogeneous medium at spatial resolutions that are finer than those adopted in typical hydrologic and soil physics applications. Although methods for soil water pressure measurement can be readily found in literature, a technique for measuring “air pressure” in wet soil is not well-established or documented. Hydrophobic porous ceramic cups have been used to measure non-wetting NAPL phase pressure in two-phase systems. However, our preliminary tests using the hydrophobic ceramic cups installed in highly wet soil showed that under conditions of fast drainage of the wetting fluid that is replaced by air, it typically took some time before the cups responded to register the air pressure. Therefore, an attempt was made to develop a more robust method where the time lag is minimized. The tested materials were; 1) ceramic porous cups, 2) sintered stainless steel cups, 3) porous glass discs, and 4) non-woven PTFE fabric. The ceramic cups, sintered stainless steel cups and sintered porous glass discs required hydrophobic treatment, whereas the non-woven PTFE fabric is hydrophobic by itself. To treat the ceramic porous cups, the method proposed by Parker and Lenhard [1988] was adopted. The sintered porous stainless steel cups and porous glass discs were treated by a commercially available water repellant compound. For those four materials, contact angle, water entry pressure, and time lag to respond to an imposed pressure were measured. The best performing material was then tested in a simple heterogeneous column. The column was packed using two sands to form three layers where the coarser sand was sandwitched by two layers of a finer sand. In each layer, soil moisture, water pressure and air pressure were monitored. The soil was initially saturated and suction at the bottom was gradually increased to induce wetting fluid drainage, and followed by a wetting cycle. In the drainage cycle, the coarse middle layer did not drain until air front reached the bottom of the top fine layer. Once the air front reached the fine-coarse interface, air was quickly pulled into the coarse layer. The results showed that the newly developed hydrophobic material showed very small time lag and captured the abrupt air pressure change in the wet soil. In the wetting cycle, we observed positive air pressure which indicated entrapment of air and its compression as wetting proceeded. This behavior cannot be evaluated properly without the rapid measurement of air pressure. The method is currently being applied in a large 2D vertical aquifer with a structured heterogeneity to investigate how air pathways are formed under various flux/temperature conditions at the soil surface.

Intracranial and Intraocular Pressure at the Lamina Cribrosa: Gradient Effects.

PubMed

Jóhannesson, Gauti; Eklund, Anders; Lindén, Christina

2018-04-12

A pressure difference between the intraocular and intracranial compartments at the site of the lamina cribrosa has been hypothesized to have a pathophysiological role in several optic nerve head diseases. This paper reviews the current literature on the translamina cribrosa pressure difference (TLCPD), the associated pressure gradient, and its potential pathophysiological role, as well as the methodology to assess TLCPD. For normal-tension glaucoma (NTG), initial studies indicated low intracranial pressure (ICP) while recent findings indicate that a reduced ICP is not mandatory. Data from studies on the elevated TLCPD as a pathophysiological factor of NTG are equivocal. From the identification of potential postural effects on the cerebrospinal fluid (CSF) communication between the intracranial and retrolaminar space, we hypothesize that the missing link could be a dysfunction of an occlusion mechanism of the optic nerve sheath around the optic nerve. In upright posture, this could cause an elevated TLCPD even with normal ICP and we suggest that this should be investigated as a pathophysiological component in NTG patients.

Overcoming the four toughest management challenges. Increase your effectiveness by using situational leadership.

PubMed

Ketchum, S M

1991-01-01

The high-pressure work environment of the clinical laboratory presents significant challenges for managers. Often thrust into supervisory roles without formal management training, laboratory managers must find ways to delegate tasks, mediate conflict, minimize office politics, and build effective teams out of employees who may be quite diverse in their experience levels, motivation levels, and cultural backgrounds. This article explores the concept of situational leadership, which was developed by Ken Blanchard and Paul Hersey, and its applicability within the clinical laboratory. This practical paradigm involves matching one of four distinct management styles to the four development levels of employees. Each leadership style is explained, along with guidelines for giving performance feedback to employees, so that managers can evaluate their own supervisory styles. Finally, step-by-step recommendations for coping with the four management roles of delegator, referee, influencer, and team builder are presented.

Barriers and facilitators to preventing pressure ulcers in nursing home residents: A qualitative analysis informed by the Theoretical Domains Framework.

PubMed

Lavallée, Jacqueline F; Gray, Trish A; Dumville, Jo; Cullum, Nicky

2018-06-01

Pressure ulcers are areas of localised damage to the skin and underlying tissue; and can cause pain, immobility, and delay recovery, impacting on health-related quality of life. The individuals who are most at risk of developing a pressure ulcer are those who are seriously ill, elderly, have impaired mobility and/or poor nutrition; thus, many nursing home residents are at risk. To understand the context of pressure ulcer prevention in nursing homes and to explore the potential barriers and facilitators to evidence-informed practices. Semi-structured interviews were conducted with nursing home nurses, healthcare assistants and managers, National Health Service community-based wound specialist nurses (known in the UK as tissue viability nurses) and a nurse manager in the North West of England. The interview guide was developed using the Theoretical Domains Framework to explore the barriers and facilitators to pressure ulcer prevention in nursing home residents. Data were analysed using a framework analysis and domains were identified as salient based on their frequency and the potential strength of their impact. 25 participants (nursing home: 2 managers, 7 healthcare assistants, 11 qualified nurses; National Health Service community services: 4 tissue viability nurses, 1 manager) were interviewed. Depending upon the behaviours reported and the context, the same domain could be classified as both a barrier and a facilitator. We identified seven domains as relevant in the prevention of pressure ulcers in nursing home residents mapping to four "barrier" domains and six "facilitator" domains. The four "barrier" domains were knowledge, physical skills, social influences and environmental context and resources and the six "facilitator" domains were interpersonal skills, environmental context and resources, social influences, beliefs about capabilities, beliefs about consequences and social/professional role and identity). Knowledge and insight into these barriers and facilitators provide a theoretical understanding of the complexities in preventing pressure ulcers with reference to the staff capabilities, opportunities and motivation related to pressure ulcer prevention. Pressure ulcer prevention in nursing home residents is complex and is influenced by several factors. The findings will inform a theory and evidence-based intervention to aid the prevention of pressure ulcers in nursing home settings. Copyright © 2018 The Author(s). Published by Elsevier Ltd.. All rights reserved.

Hydrostatic pulpal pressure effect upon microleakage.

PubMed

Roberts, Howard W; Pashley, David H

2012-02-01

To evaluate if hydrostatic pulpal pressure plays a role in reducing microleakage. Uniform Class 5 preparations were accomplished on human molars with one margin on root dentin. Prepared teeth were randomly placed in one of three groups: (1) Hydrostatic pressure simulation at 20 cm pulpal pressure; (2) Hydrostatic pressure simulation but no pressure applied (positive control); and (3) Conventional microleakage method. Specimens were subjected to 24 hours methylene blue dye, sectioned, and microleakage assessed as a function of microleakage length versus entire preparation wall length using a traveling microscope. Hydrostatic pressure specimens demonstrated less gingival wall microleakage than the control groups while no difference was found between occlusal preparation walls.

Mesh materials and hernia repair

PubMed Central

Elango, Santhini; Perumalsamy, Sakthivel; Ramachandran, Krishnakumar; Vadodaria, Ketankumar

2017-01-01

Hernia incidence has been observed since ancient time. Advancement in the medical textile industry came up with the variety of mesh materials to repair hernia, but none of them are without complications including recurrence of hernia. Therefore individuals once developed with the hernia could not lead a healthy and comfortable life. This drawn attention of surgeons, patients, researchers and industry to know the exact mechanism behind its development, complications and recurrence. Recent investigations highlighted the role of genetic factors and connective tissue disorders being the reason for the development of hernia apart from the abnormal pressure that is known to develop during other disease conditions. This review discusses different mesh materials, their advantages and disadvantages and their biological response after its implantation. PMID:28840830

Beyond the Entrepreneurial University: The Potential Role of South Africa's Historically Disadvantaged Institutions in Reconstruction and Development

NASA Astrophysics Data System (ADS)

Subotzky, George

1999-11-01

The author identifies two tendencies affecting higher education. On the one hand, universities and colleges are under pressure to become more market-oriented and to respond to rapid changes in information technology and knowledge production. On the other hand, there is a growing concern that they should work for the benefit of society, promoting social equity and responding to community needs. The author argues that partnerships between the community and institutions of higher education are an effective way of contributing to community development. He describes the potential of South Africa's historically disadvantaged institutions to contribute to reconstruction and development in the aftermath of apartheid.

The curvilinear relationship between work pressure and momentary task performance: the role of state and trait core self-evaluations

PubMed Central

Hofmans, Joeri; Debusscher, Jonas; Dóci, Edina; Spanouli, Andromachi; De Fruyt, Filip

2015-01-01

Whereas several studies have demonstrated that core self-evaluations (CSE)–or one’s appraisals about one’s own self-worth, capabilities, and competences–relate to job outcomes, less is known about the mechanisms underlying these relationships. In the present study, we address this issue by examining the role of within- and between-person variation in CSE in the relationship between work pressure and task performance. We hypothesized that (a) work pressure relates to task performance in a curvilinear way, (b) state CSE mediates the curvilinear relationship between work pressure and task performance, and (c) the relationship between work pressure and state CSE is moderated by trait CSE. Our hypotheses were tested via a 10-day daily diary study with 55 employees in which trait CSE was measured at baseline, while work pressure, task performance, and state CSE were assessed on a daily basis. Bayesian multilevel path analysis showed that work pressure affects task performance via state CSE, with state CSE increasing as long as the employee feels that (s)he is able to handle the work pressure, while it decreases when the level of work pressure exceeds the employees’ coping abilities. Moreover, we found that for people low on trait CSE, the depleting effect of work pressure via state CSE happens for low levels of work pressure, while for people high in trait CSE the depleting effect is located at high levels of work pressure. Together, our findings suggest that the impact of work pressure on task performance is driven by a complex interplay of between- and within-person differences in CSE. PMID:26579053

Earthquakes, fluid pressures and rapid subduction zone metamorphism

NASA Astrophysics Data System (ADS)

Viete, D. R.

2013-12-01

High-pressure/low-temperature (HP/LT) metamorphism is commonly incomplete, meaning that large tracts of rock can remain metastable at blueschist- and eclogite-facies conditions for timescales up to millions of years [1]. When HP/LT metamorphism does take place, it can occur over extremely short durations (<<1 Myr) [1-2]. HP/LT metamorphism must be associated with processes that allow large volumes of rock to remain unaffected over long periods of time, but then suddenly undergo localized metamorphism. Existing models for HP/LT metamorphism have focussed on the role of fluids in providing heat for metamorphism [2] or catalyzing metamorphic reactions [1]. Earthquakes in subduction zone settings can occur to depths of 100s of km. Metamorphic dehydration and the associated development of elevated pore pressures in HP/LT metamorphic rocks has been identified as a cause of earthquake activity at such great depths [3-4]. The process of fracturing/faulting significantly increases rock permeability, causing channelized fluid flow and dissipation of pore pressures [3-4]. Thus, deep subduction zone earthquakes are thought to reflect an evolution in fluid pressure, involving: (1) an initial increase in pore pressure by heating-related dehydration of subduction zone rocks, and (2) rapid relief of pore pressures by faulting and channelized flow. Models for earthquakes at depth in subduction zones have focussed on the in situ effects of dehydration and then sudden escape of fluids from the rock mass following fracturing [3-4]. On the other hand, existing models for rapid and incomplete metamorphism in subduction zones have focussed only on the effects of heating and/or hydration with the arrival of external fluids [1-2]. Significant changes in pressure over very short timescales should result in rapid mineral growth and/or disequilibrium texture development in response to overstepping of mineral reaction boundaries. The repeated process of dehydration-pore pressure development-earthquake-pore pressure relief could conceivably produce a record of episodic HP/LT metamorphism driven by rapid pressure pulses. A new hypothesis is presented for the origins of HP/LT metamorphism: that HP/LT metamorphism is driven by effective pressure pulses caused by localized, earthquake-related modifications to fluid pressures in the subducted slab. In other words, HP/LT metamorphism marks abrupt changes in stress state within the subducted slab, driven by earthquake rupture and fluid flow, and involving a rapid return toward lithostatic pressure from effective pressures well below lithostatic. References: 1. Bjørnerud, MG, Austrheim, H & Lund, MG, 2002. Processes leading to eclogitization (densification) of subducted and tectonically buried crust. Journal of Geophysical Research 107, 2252. 2. Camacho, A, Lee, JKW, Hensen, BJ & Braun, J, 2005. Short-lived orogenic cycles and the eclogitization of cold crust by spasmodic hot fluids. Nature 435, 1191-1196. 3. Green, HW & Houston, H, 1995. The mechanics of deep earthquakes. Annual Reviews of Earth and Planetary Sciences 23, 169-213. 4. Hacker, BR, Peacock, SM, Abers, GA & Holloway, SD, 2003. Subduction factory 2. Are intermediate-depth earthquakes in subducting slabs linked to metamorphic dehydration reactions?. Journal of Geophysical Research 108, 2030.

Comparative Genomics Provide Insights into Evolution of Trichoderma Nutrition Style

PubMed Central

Xie, Bin-Bin; Qin, Qi-Long; Shi, Mei; Chen, Lei-Lei; Shu, Yan-Li; Luo, Yan; Wang, Xiao-Wei; Rong, Jin-Cheng; Gong, Zhi-Ting; Li, Dan; Sun, Cai-Yun; Liu, Gui-Ming; Dong, Xiao-Wei; Pang, Xiu-Hua; Huang, Feng; Liu, Weifeng; Chen, Xiu-Lan; Zhou, Bai-Cheng; Zhang, Yu-Zhong; Song, Xiao-Yan

2014-01-01

Saprotrophy on plant biomass is a recently developed nutrition strategy for Trichoderma. However, the physiology and evolution of this new nutrition strategy is still elusive. We report the deep sequencing and analysis of the genome of Trichoderma longibrachiatum, an efficient cellulase producer. The 31.7-Mb genome, smallest among the sequenced Trichoderma species, encodes fewer nutrition-related genes than saprotrophic T. reesei (Tr), including glycoside hydrolases and nonribosomal peptide synthetase–polyketide synthase. Homology and phylogenetic analyses suggest that a large number of nutrition-related genes, including GH18 chitinases, β-1,3/1,6-glucanases, cellulolytic enzymes, and hemicellulolytic enzymes, were lost in the common ancestor of T. longibrachiatum (Tl) and Tr. dN/dS (ω) calculation indicates that all the nutrition-related genes analyzed are under purifying selection. Cellulolytic enzymes, the key enzymes for saprotrophy on plant biomass, are under stronger purifying selection pressure in Tl and Tr than in mycoparasitic species, suggesting that development of the nutrition strategy of saprotrophy on plant biomass has increased the selection pressure. In addition, aspartic proteases, serine proteases, and metalloproteases are subject to stronger purifying selection pressure in Tl and Tr, suggesting that these enzymes may also play important roles in the nutrition. This study provides insights into the physiology and evolution of the nutrition strategy of Trichoderma. PMID:24482532

Pressure Mapping and Efficiency Analysis of an EPPLER 857 Hydrokinetic Turbine

NASA Astrophysics Data System (ADS)

Clark, Tristan

A conceptual energy ship is presented to provide renewable energy. The ship, driven by the wind, drags a hydrokinetic turbine through the water. The power generated is used to run electrolysis on board, taking the resultant hydrogen back to shore to be used as an energy source. The basin efficiency (Power/thrust*velocity) of the Hydrokinetic Turbine (HTK) plays a vital role in this process. In order to extract the maximum allowable power from the flow, the blades need to be optimized. The structural analysis of the blade is important, as the blade will undergo high pressure loads from the water. A procedure for analysis of a preliminary Hydrokinetic Turbine blade design is developed. The blade was designed by a non-optimized Blade Element Momentum Theory (BEMT) code. Six simulations were run, with varying mesh resolution, turbulence models, and flow region size. The procedure was developed that provides detailed explanation for the entire process, from geometry and mesh generation to post-processing analysis tools. The efficiency results from the simulations are used to study the mesh resolution, flow region size, and turbulence models. The results are compared to the BEMT model design targets. Static pressure maps are created that can be used for structural analysis of the blades.

Comparative genomics provide insights into evolution of trichoderma nutrition style.

PubMed

Xie, Bin-Bin; Qin, Qi-Long; Shi, Mei; Chen, Lei-Lei; Shu, Yan-Li; Luo, Yan; Wang, Xiao-Wei; Rong, Jin-Cheng; Gong, Zhi-Ting; Li, Dan; Sun, Cai-Yun; Liu, Gui-Ming; Dong, Xiao-Wei; Pang, Xiu-Hua; Huang, Feng; Liu, Weifeng; Chen, Xiu-Lan; Zhou, Bai-Cheng; Zhang, Yu-Zhong; Song, Xiao-Yan

2014-02-01

Saprotrophy on plant biomass is a recently developed nutrition strategy for Trichoderma. However, the physiology and evolution of this new nutrition strategy is still elusive. We report the deep sequencing and analysis of the genome of Trichoderma longibrachiatum, an efficient cellulase producer. The 31.7-Mb genome, smallest among the sequenced Trichoderma species, encodes fewer nutrition-related genes than saprotrophic T. reesei (Tr), including glycoside hydrolases and nonribosomal peptide synthetase-polyketide synthase. Homology and phylogenetic analyses suggest that a large number of nutrition-related genes, including GH18 chitinases, β-1,3/1,6-glucanases, cellulolytic enzymes, and hemicellulolytic enzymes, were lost in the common ancestor of T. longibrachiatum (Tl) and Tr. dN/dS (ω) calculation indicates that all the nutrition-related genes analyzed are under purifying selection. Cellulolytic enzymes, the key enzymes for saprotrophy on plant biomass, are under stronger purifying selection pressure in Tl and Tr than in mycoparasitic species, suggesting that development of the nutrition strategy of saprotrophy on plant biomass has increased the selection pressure. In addition, aspartic proteases, serine proteases, and metalloproteases are subject to stronger purifying selection pressure in Tl and Tr, suggesting that these enzymes may also play important roles in the nutrition. This study provides insights into the physiology and evolution of the nutrition strategy of Trichoderma.

Mechanical Behavior of Low Porosity Carbonate Rock: From Brittle Creep to Ductile Creep.

NASA Astrophysics Data System (ADS)

Nicolas, A.; Fortin, J.; Gueguen, Y.

2014-12-01

Mechanical compaction and associated porosity reduction play an important role in the diagenesis of porous rocks. They may also affect reservoir rocks during hydrocarbon production, as the pore pressure field is modified. This inelastic compaction can lead to subsidence, cause casing failure, trigger earthquake, or change the fluid transport properties. In addition, inelastic deformation can be time - dependent. In particular, brittle creep phenomena have been deeply investigated since the 90s, especially in sandstones. However knowledge of carbonates behavior is still insufficient. In this study, we focus on the mechanical behavior of a 14.7% porosity white Tavel (France) carbonate rock (>98% calcite). The samples were deformed in a triaxial cell at effective confining pressures ranging from 0 MPa to 85 MPa at room temperature and 70°C. Experiments were carried under dry and water saturated conditions in order to explore the role played by the pore fluids. Two types of experiments have been carried out: (1) a first series in order to investigate the rupture envelopes, and (2) a second series with creep experiments. During the experiments, elastic wave velocities (P and S) were measured to infer crack density evolution. Permeability was also measured during creep experiments. Our results show two different mechanical behaviors: (1) brittle behavior is observed at low confining pressures, whereas (2) ductile behavior is observed at higher confining pressures. During creep experiments, these two behaviors have a different signature in term of elastic wave velocities and permeability changes, due to two different mechanisms: development of micro-cracks at low confining pressures and competition between cracks and microplasticity at high confining pressure. The attached figure is a summary of 20 triaxial experiments performed on Tavel limestone under different conditions. Stress states C',C* and C*' and brittle strength are shown in the P-Q space: (a) 20°C and dry, (b) 20°C and water saturated samples, (c) 70°C dry and (d) summary of all the experiments. Three regimes of inelastic and failure modes are observed: brittle failure, shear-enhanced compaction and dilatant cataclastic flow.

The Role of Internalized Stereotyping, Parental Pressure, and Parental Support on Asian Americans' Choice of College Major

ERIC Educational Resources Information Center

Shen, Frances C.

2015-01-01

The author explored the relationship between internalized stereotyping, parental pressure, and parental support on major choices among 315 Asian American undergraduate and graduate students. Results indicated that parental support, but not parental pressure, toward certain majors was associated with more stereotypical major choices. In addition,…

The role of barrier protection ain pressure ulcer prevention.

PubMed

Stephen-Haynes, Jackie

This article considers the anatomy and physiology of the skin, the natural protection the skin provides in relation to barrier protection and the importance of barrier protection in pressure ulcer prevention. The current national pressure ulcer agenda including high impact actions and the SSKIN care bundle, along with their implementation within one NHS Health Care Trust are discussed.

SPAKling insight into blood pressure regulation

PubMed Central

Castañeda-Bueno, María; Gamba, Gerardo

2010-01-01

Arterial hypertension is one of the most important health problems in industrialized cities. Blood pressure levels are influenced by renal salt handling and salt reabsorption in the kidney. In this Closeup, Castañeda-Bueno and Gamba discuss the work from Alessi and coworkers on the in vivo roles of the SPAK kinase in defining blood pressure levels. PMID:20112249

Evidence for cardiovascular autonomic dysfunction in neonates with coarctation of the aorta.

PubMed

Polson, Jaimie W; McCallion, Naomi; Waki, Hidefumi; Thorne, Gareth; Tooley, Mark A; Paton, Julian F R; Wolf, Andrew R

2006-06-20

Coarctation of the aorta (CoA) is associated with hypertension and abnormalities of blood pressure control, which persist after late repair. Assumptions that neonatal repair would prevent development of blood pressure abnormalities have not been supported by recent data. We hypothesized that early pathological adjustment of autonomic cardiovascular function may already be established in the neonate with coarctation. We studied 8 otherwise well neonates with simple CoA and compared measures of spontaneous baroreflex sensitivity, heart rate variability, and blood pressure variability with 13 healthy newborn babies. Spontaneous baroreflex sensitivity was calculated with sequence methodology from an ECG, and noninvasive blood pressure was recorded with a Portapres. Heart rate variability was determined with time- and frequency-domain measures. Blood pressure variability was measured in the frequency domain. In comparison with normal controls, neonates with CoA had raised blood pressure (78.9+/-3.8 versus 67.1+/-2.1 mm Hg), depressed baroreflex sensitivity (8.7+/-1.5 versus 13.8+/-1.1 ms/mm Hg), reduced heart rate variability (total power 16.5+/-3.1 versus 31.5+/-2.2 ms2), and an increase in the high-frequency component of blood pressure variability (3.1+/-0.3 versus 2.2+/-0. 2 mm Hg2). This is not the pattern expected if neonates with CoA simply had subclinical cardiac failure. These data suggest that infants with CoA already show signs of pathological adjustment of autonomic cardiovascular homeostasis. Further longitudinal studies are required to determine whether these alterations play a role in the increased risk of late hypertension in these patients.

Experimental evaluation of the pressure and temperature dependence of ion-induced nucleation.

PubMed

Munir, Muhammad Miftahul; Suhendi, Asep; Ogi, Takashi; Iskandar, Ferry; Okuyama, Kikuo

2010-09-28

An experimental system for the study of ion-induced nucleation in a SO(2)/H(2)O/N(2) gas mixture was developed, employing a soft x-ray at different pressure and temperature levels. The difficulties associated with these experiments included the changes in physical properties of the gas mixture when temperature and pressure were varied. Changes in the relative humidity (RH) as a function of pressure and temperature also had a significant effect on the different behaviors of the mobility distributions of particles. In order to accomplish reliable measurement and minimize uncertainties, an integrated on-line control system was utilized. As the pressure decreased in a range of 500-980 hPa, the peak concentration of both ions and nanometer-sized particles decreased, which suggests that higher pressure tended to enhance the growth of particles nucleated by ion-induced nucleation. Moreover, the modal diameters of the measured particle size distributions showed a systematic shift to larger sizes with increasing pressure. However, in the temperature range of 5-20 °C, temperature increases had no significant effects on the mobility distribution of particles. The effects of residence time, RH (7%-70%), and SO(2) concentration (0.08-6.7 ppm) on ion-induced nucleation were also systematically investigated. The results show that the nucleation and growth were significantly dependent on the residence time, RH, and SO(2) concentration, which is in agreement with both a previous model and previous observations. This research will be inevitable for a better understanding of the role of ions in an atmospheric nucleation mechanism.

Tissue kallikrein deficiency, insulin resistance, and diabetes in mouse and man.

PubMed

Potier, Louis; Waeckel, Ludovic; Fumeron, Fréderic; Bodin, Sophie; Fysekidis, Marinos; Chollet, Catherine; Bellili, Naima; Bonnet, Fabrice; Gusto, Gaëlle; Velho, Gilberto; Marre, Michel; Alhenc-Gelas, François; Roussel, Ronan; Bouby, Nadine

2014-05-01

The kallikrein-kinin system has been suggested to participate in the control of glucose metabolism. Its role and the role of angiotensin-I-converting enzyme, a major kinin-inactivating enzyme, are however the subject of debate. We have evaluated the consequence of deficiency in tissue kallikrein (TK), the main kinin-forming enzyme, on the development of insulin resistance and diabetes in mice and man. Mice with inactivation of the TK gene were fed a high-fat diet (HFD) for 3 months, or crossed with obese, leptin-deficient (ob/ob) mice to generate double ob/ob-TK-deficient mutants. In man, a loss-of-function polymorphism of the TK gene (R53H) was studied in a large general population cohort tested for insulin resistance, the DESIR study (4843 participants, 9 year follow-up). Mice deficient in TK gained less weight on the HFD than their WT littermates. Fasting glucose level was increased and responses to glucose (GTT) and insulin (ITT) tolerance tests were altered at 10 and 16 weeks on the HFD compared with standard on the diet, but TK deficiency had no influence on these parameters. Likewise, ob-TK⁻/⁻ mice had similar GTT and ITT responses to those of ob-TK⁺/⁺ mice. TK deficiency had no effect on blood pressure in either model. In humans, changes over time in BMI, fasting plasma glucose, insulinemia, and blood pressure were not influenced by the defective 53H-coding TK allele. The incidence of diabetes was not influenced by this allele. These data do not support a role for the TK-kinin system, protective or deleterious, in the development of insulin resistance and diabetes.

Role of the Renin-Angiotensin System, Renal Sympathetic Nerve System, and Oxidative Stress in Chronic Foot Shock-Induced Hypertension in Rats

PubMed Central

Dong, Tao; Chen, Jing-Wei; Tian, Li-Li; Wang, Lin-Hui; Jiang, Ren-Di; Zhang, Zhe; Xu, Jian-Bing; Zhao, Xiao-Dong; Zhu, Wei; Wang, Guo-Qing; Sun, Wan-Ping; Zhang, Guo-Xing

2015-01-01

Objective: The renin-angiotensin system (RAS) and renal sympathetic nerve system (RSNS) are involved in the development of hypertension. The present study is designed to explore the possible roles of the RAS and the RSNS in foot shock-induced hypertension. Methods: Male Sprague-Dawley rats were divided into six groups: control, foot shock, RSNS denervation, denervation plus foot shock, Captopril (angiotensin I converting enzyme inhibitor, ACE inhibitor) plus foot shock, and Tempol (superoxide dismutase mimetic) plus foot shock. Rats received foot shock for 14 days. We measured the quantity of thiobarbituric acid reactive substances (TBARS), corticosterone, renin, and angiotensin II (Ang II) in plasma, the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), and renal noradrenaline content. RAS component mRNA and protein levels were quantified in the cerebral cortex and hypothalamus. Results: The two week foot shock treatment significantly increased systolic blood pressure, which was accompanied by an increase in angiotensinogen, renin, ACE1, and AT1a mRNA and protein expression in the cerebral cortex and hypothalamus, an increase of the plasma concentrations of renin, Ang II, corticosterone, and TBARS, as well as a decrease in plasma SOD and GSH-Px activities. Systolic blood pressure increase was suppressed by denervation of the RSNS or treatment with Captopril or Tempol. Interestingly, denervation or Tempol treatment both decreased main RAS components not only in the circulatory system, but also in the central nervous system. In addition, decreased antioxidant levels and increased TBARS and corticosterone levels were also partially restored by denervation or treatment with Tempol or Captopril. Conclusions: RAS, RSNS and oxidative stress reciprocally potentiate to play important roles in the development of foot shock-induced hypertension. PMID:25999788

Role of the renin-angiotensin system, renal sympathetic nerve system, and oxidative stress in chronic foot shock-induced hypertension in rats.

PubMed

Dong, Tao; Chen, Jing-Wei; Tian, Li-Li; Wang, Lin-Hui; Jiang, Ren-Di; Zhang, Zhe; Xu, Jian-Bing; Zhao, Xiao-Dong; Zhu, Wei; Wang, Guo-Qing; Sun, Wan-Ping; Zhang, Guo-Xing

2015-01-01

The renin-angiotensin system (RAS) and renal sympathetic nerve system (RSNS) are involved in the development of hypertension. The present study is designed to explore the possible roles of the RAS and the RSNS in foot shock-induced hypertension. Male Sprague-Dawley rats were divided into six groups: control, foot shock, RSNS denervation, denervation plus foot shock, Captopril (angiotensin I converting enzyme inhibitor, ACE inhibitor) plus foot shock, and Tempol (superoxide dismutase mimetic) plus foot shock. Rats received foot shock for 14 days. We measured the quantity of thiobarbituric acid reactive substances (TBARS), corticosterone, renin, and angiotensin II (Ang II) in plasma, the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), and renal noradrenaline content. RAS component mRNA and protein levels were quantified in the cerebral cortex and hypothalamus. The two week foot shock treatment significantly increased systolic blood pressure, which was accompanied by an increase in angiotensinogen, renin, ACE1, and AT1a mRNA and protein expression in the cerebral cortex and hypothalamus, an increase of the plasma concentrations of renin, Ang II, corticosterone, and TBARS, as well as a decrease in plasma SOD and GSH-Px activities. Systolic blood pressure increase was suppressed by denervation of the RSNS or treatment with Captopril or Tempol. Interestingly, denervation or Tempol treatment both decreased main RAS components not only in the circulatory system, but also in the central nervous system. In addition, decreased antioxidant levels and increased TBARS and corticosterone levels were also partially restored by denervation or treatment with Tempol or Captopril. RAS, RSNS and oxidative stress reciprocally potentiate to play important roles in the development of foot shock-induced hypertension.

The TurbEFA Field Experiment—Measuring the Influence of a Forest Clearing on the Turbulent Wind Field

NASA Astrophysics Data System (ADS)

Queck, Ronald; Bernhofer, Christian; Bienert, Anne; Schlegel, Fabian

2016-09-01

Forest ecosystems play an important role in the interaction between the land surface and the atmosphere. Measurements and modelling efforts have revealed significant uncertainties in state-of-the-art flux assessments due to spatial inhomogeneities in the airflow and land surface. Here, a field experiment is used to describe the turbulent flow across a typical Central European forest clearing. A three-dimensional model of the inhomogeneous forest stand was developed using an innovative approach based on terrestrial laser-scanner technology. The comparison of the wind statistics of two measurement campaigns (5 and 12 months long) showed the spatial and temporal representativeness of the ultrasonic anemometer measurements within the canopy. An improved method for the correction of the vertical velocity enables the distinction between the instrumental offsets and the vertical winds due to the inclination of the instrument. Despite a 13 % fraction of deciduous plants within the otherwise evergreen canopy, the effects of phenological seasons on the velocity profiles were small. The data classified according to the wind speed revealed the intermittent nature of recirculating air in the clearing. Furthermore, the development of sub-canopy wind-speed maxima is explained by considering the velocity moments and the momentum equation (including measurements of the local pressure gradient). Clearings deflect the flow downward and feed the sub-canopy flow, i.e., advective fluxes, according to wind speed and, likely, clearing size, whereas local pressure gradients play an important role in the development of sub-canopy flow. The presented dataset is freely available at the project homepage.

Structural, mechanical, electrical and wetting properties of ZrNx films deposited by Ar/N2 vacuum arc discharge: Effect of nitrogen partial pressure

NASA Astrophysics Data System (ADS)

Abdallah, B.; Naddaf, M.; A-Kharroub, M.

2013-03-01

Non-stiochiometric zirconium nitride (ZrNx) thin films have been deposited on silicon substrates by vacuum arc discharge of (N2 + Ar) gas mixtures at different N2 partial pressure ratio. The microstructure, mechanical, electrical and wetting properties of these films are studied by means of X-ray diffraction (XRD), micro-Raman spectroscopy, Rutherford back scattering (RBS) technique, conventional micro-hardness testing, electrical resistivity, atomic force microscopy (AFM) and contact angle (CA) measurements. RBS results and analysis show that the (N/Zr) ratio in the film increases with increasing the N2 partial pressure. A ZrNx film with (Zr/N) ratio in the vicinity of stoichiometric ZrN is obtained at N2 partial pressure of 10%. XRD and Raman results indicate that all deposited films have strained cubic crystal phase of ZrN, regardless of the N2 partial pressure. On increasing the N2 partial pressure, the relative intensity of (1 1 1) orientation with respect to (2 0 0) orientation is seen to decrease. The effect of N2 partial pressure on micro-hardness and the resistivity of the deposited film is revealed and correlated to the alteration of grain size, crystallographic texture, stoichiometry and residual stress developed in the film. In particular, it is found that residual stress and nitrogen incorporation in the film play crucial role in the alteration of micro-hardness and resistivity respectively. In addition, CA and AFM results demonstrate that as N2 partial pressure increases, both the surface hydrophobicity and roughness of the deposited film increase, leading to a significant decrease in the film surface free energy (SFE).

On contribution of energetic and heavy ions to the plasma pressure: Storm Sept 27 - Oct 4, 2002

NASA Astrophysics Data System (ADS)

Kronberg, E. A.; Mouikis, C.; Kistler, L. M.; Dandouras, I. S.; Daly, P. W.; Welling, D. T.; Grigorenko, E. E.

2015-12-01

Contribution of the energetic ions (>> 40 keV) and of heavy ions into the total plasma pressure is often neglected. In this study we evaluate the contribution of these components for the storm observed from September 27 to October 4 in 2002. The thermal component of the pressure for the protons, helium and oxygen at 0--40 keV/q is measured by the Cluster/CIS/CODIF sensor. The contribution of the energetic ions at energies >> 40 keV is calculated from the Cluster/RAPID/IIMS observations. The results show that before the storm has initiated, the contribution of the energetic ions in to the total pressure is indeed negligible in the tail plasma sheet, less than ˜1%. However, with the storm development contribution of the energetic part becomes significant, up to ˜30%, towards the recovery phase and cannot be neglected. Heavy ions contribute to the 27% of the total pressure and half of them are energetic. The contribution of energetic ions to the pressure of the ring current (L≃5) is significant. The heavy ions play a dominant role in the plasma pressure, about 62% during the main phase of the magnetic storm. Half of them are energetic ions. The SWMF/BATS-R-US MHD model underestimates the contribution of the energetic and heavy ions in to the ion distribution in the magnetotail plasma sheet and the ring current. The ring current plasma pressure distorts the terrestrial internal magnetic field and defines magnetic storm. Therefore, it is essential to take in to account the contribution of the energetic and heavy ions.

Pressure ulcers: implementation of evidence-based nursing practice.

PubMed

Clarke, Heather F; Bradley, Chris; Whytock, Sandra; Handfield, Shannon; van der Wal, Rena; Gundry, Sharon

2005-03-01

A 2-year project was carried out to evaluate the use of multi-component, computer-assisted strategies for implementing clinical practice guidelines. This paper describes the implementation of the project and lessons learned. The evaluation and outcomes of implementing clinical practice guidelines to prevent and treat pressure ulcers will be reported in a separate paper. The prevalence and incidence rates of pressure ulcers, coupled with the cost of treatment, constitute a substantial burden for our health care system. It is estimated that treating a pressure ulcer can increase nursing time up to 50%, and that treatment costs per ulcer can range from US$10,000 to $86,000, with median costs of $27,000. Although evidence-based guidelines for prevention and optimum treatment of pressure ulcers have been developed, there is little empirical evidence about the effectiveness of implementation strategies. The study was conducted across the continuum of care (primary, secondary and tertiary) in a Canadian urban Health Region involving seven health care organizations (acute, home and extended care). Trained surveyors (Registered Nurses) determined the prevalence and incidence of pressure ulcers among patients in these organizations. The use of a computerized decision-support system assisted staff to select optimal, evidence-based care strategies, record information and analyse individual and aggregate data. Evaluation indicated an increase in knowledge relating to pressure ulcer prevention, treatment strategies, resources required, and the role of the interdisciplinary team. Lack of visible senior nurse leadership; time required to acquire computer skills and to implement new guidelines; and difficulties with the computer system were identified as barriers. There is a need for a comprehensive, supported and sustained approach to implementation of evidence-based practice for pressure ulcer prevention and treatment, greater understanding of organization-specific barriers, and mechanisms for addressing the barriers.

Biomechanical aspects of axonal damage in glaucoma: a brief review1

PubMed Central

Stowell, Cheri; Burgoyne, Claude; Tamm, Ernst R.; Ethier, C. Ross

2017-01-01

The biomechanical environment within the optic nerve head (ONH) is complex and is likely directly involved in the loss of retinal ganglion cells (RGCs) in glaucoma. Unfortunately, our understanding of this process is poor. Here we describe factors that influence ONH biomechanics, including ONH connective tissue microarchitecture and anatomy; intraocular pressure (IOP); and cerebrospinal fluid pressure (CSFp). We note that connective tissue factors can vary significantly from one individual to the next, as well as regionally within an eye, and that the understanding of ONH biomechanics is hindered by anatomical differences between small-animal models of glaucoma (rats and mice) and humans. Other challenges of using animal models of glaucoma to study the role of biomechanics include the complexity of assessing the degree of glaucomatous progression; and inadequate tools for monitoring and consistently elevating IOP in animal models. We conclude with a consideration of important open research questions/challenges in this area, including: (i) Creating a systems biology description of the ONH; (ii) addressing the role of astrocyte connective tissue remodeling and reactivity in glaucoma; (iii) providing a better characterization of ONH astrocytes and non-astrocytic constituent cells; (iv) better understanding the role of ONH astrocyte phagocytosis, proliferation and death; (v) collecting gene expression and phenotype data on a larger, more coordinated scale; and (vi) developing an implantable IOP sensor. PMID:28223180

Hegemony in the Roma family.

PubMed

Mrhálek, Tomáš; Lidová, Lenka; Kajanová, Alena

2015-01-01

This article is intended to describe the current hegemonic masculinity within the Roma family structure in the Czech Republic, with regard to changes related to developments in the majority society and the current socioeconomic situation of the Roma. The theoretical context of this article is based on the paradigm of masculine hegemony as it exists and has existed in the Roma families. Data for the study came from semi-structured interviews with 30 Roma females and 30 Roma males living as couples, in three Czech cities. The main finding reveals a dichotomy between the traditional roles of Roma women, i.e. care for the family and the household, and the present functions, i.e. contributing to the family income through social benefits. We observed a decline in the traditional role of Roma men, who were often unemployed. We related the change in the roles of men to the "non-functionality of the men", contributing to the emerging potential for emancipation of Roma women. However, the traditional patriarchal Roma family is structured such that men are given the main decision making powers, which has slowed changes in marginalized Roma families. Additionally, social pressures against women as well as socially conditioned pressures that act to preserve hegemonic masculinity, have largely prevented the realization of the potential for emancipation of Roma women, or if a woman tries to leave her non-functioning husband.

Relationship between intra-abdominal pressure and trunk EMG.

PubMed

McGill, S M; Sharratt, M T

1990-05-01

Intra-abdominal pressure (IAP) has been proposed as an important mechanism in manual lifting and breathing mechanics. Direct (invasive) measures of IAP have required the swallowing of a radio transducer or insertion of a pressure sensor into the rectum or down the oesophagus to the stomach. The purpose of this study was to investigate the relationship between a non-invasive method (EMG) and IAP. Several tasks involving abdominal muscle activation were performed to assess whether or not IAP played a common role in these tasks. IAP and EMG from rectus abdominis, the abdominal obliques, intercostals and erector spinae were measured. Peak IAP reached 340 mmHg (valsalva) for one subject but most values were less than 100 mmHg for tasks other than valsalva. The IAP and EMG data provide some insight into the role of IAP during the performance of specific tasks. Peak IAP within 60 ms of the onset of vigorous abdominal activation indicated the importance of a very rapid pressure response to abdominal muscle activation. The correlations between various muscle EMG time histories and IAP exceeded 0·80 for only two activities (i.e. r(2) = 0·82 between the intercostals and IAP during valsalva manoeuvres). These data suggest that no unifying hypothesis exists to explain the role of IAP for a wide variety of movement tasks; rather, the role of IAP is task specific. Copyright © 1990. Published by Elsevier Ltd.

Strong Extratropical Cyclone Over the US Midwest

NASA Image and Video Library

2010-10-29

NASA image acquired October 26, 2010 The storm that swept across the center of the United States on October 26 and October 27, 2010, was memorable to those who experienced it because of its strong winds, rain, hail, and widespread tornadoes. Meteorologists get excited about the storm because it set a record for the lowest pressure (not associated with a hurricane) measured over land in the continental United States. At 5:13 p.m. CDT, the weather station in Bigfork, Minnesota recorded 955.2 millibars (28.21 inches of pressure). Pressure is one indicator of a storm’s strength, and this measurement corresponds to the pressure seen in a Category 3 hurricane. This image, taken by the GOES satellite on October 26, shows the storm system circling around the area of extreme low pressure. Such extratropical cyclones form over the United States in the spring and fall, when the temperature difference from north to south is large. Warm, high-pressure air rushes toward the cooler, low-pressure air in the north. Because the Earth is rotating, the air moving in ends up circling the area of low pressure, creating the cyclone shown in the image. The intensity of the storm is determined by the pressure difference between the center and the outer edges. Extreme low pressure in the center of the storm, therefore, is an indicator that the storm was very intense. The animation shows the storm developing starting late on October 25 and running through October 27. The cyclone formed very quickly on October 26, taking a distinctive comma shape as the day went on. The storm developed so quickly, in fact, that it is classified as a bomb, an extremely fast developing storm (dropping at least one millibar of pressure per hour for 24 hours), more common over water than land. The storm was also huge. Though the area of low pressure is centered over the Upper Midwest, the storm reached from the Gulf of Mexico into Canada, and from the Rocky Mountains to the Atlantic Ocean. Extratropical cyclones bring an array of unsettled weather, including strong wind, rain, hail, and tornadoes, and this cyclone brought all of that. On October 26–27, winds gusted up to 78 miles per hour in Michigan, with high winds throughout the Midwest. The National Weather Service reported 61 tornadoes over the two days. Heavy snow also fell in the north. NASA Earth Observatory imagery created by Jesse Allen, using imagery provided courtesy of the NASA GOES Project Science Office. Caption by Holli RIebeek. Instrument: GOES Credit: NASA Earth Observatory NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Join us on Facebook

Leadership and Presenteeism among Scientific Staff: The Role of Accumulation of Work and Time Pressure

PubMed Central

Dietz, Carolin; Scheel, Tabea

2017-01-01

The present study examines the joint roles of leadership and stressors for presenteeism of scientific staff. Leaders may have an impact on employees' health, both directly through interpersonal interactions and by shaping their working conditions. In the field of science, this impact could be special because of the mentoring relationships between the employees (e.g., PhD students) and their supervisors (e.g., professors). Based on the job demands-resources framework (JD-R), we hypothesized that the pressure to be present at the workplace induced by supervisors (supervisorial pressure) is directly related to employees' presenteeism as well as indirectly via perceptions of time pressure. The conservation of resources theory (COR) states that resource loss resulting from having to deal with job demands weakens the resource pool and therefore the capacity to deal with other job demands. Thus, we hypothesized that accumulation of work moderates the relationship between supervisorial pressure and time pressure, such that the relationship is stronger when accumulation of work is high compared to if accumulation of work is low. Cross-sectional data were obtained from 212 PhD students and postdocs of 30 scientific institutions in Germany. Analysis was performed using the SPSS macro PROCESS (Hayes, 2013). Supervisorial pressure was directly associated with higher presenteeism of employees and indirectly through increased time pressure. Moreover, supervisorial pressure and accumulation of work interacted to predict time pressure, but in an unexpected way. The positive relationship between supervisorial pressure and time pressure is stronger when accumulation is low compared to if accumulation of work is high. It seems possible that job stressors do not accumulate but substitute each other. Threshold models might explain the findings. Moreover, specific patterns of interacting job demands for scientific staff should be considered in absence management. PMID:29123497

[Role of hemodynamic factors and heart volume in the prognosis of acute cardiac insufficiency during the early postoperative period in patients with mitral valve stenosis].

PubMed

Guliamov, D S; Amanov, A A; Andres, Iu P; Bazhenova, T F

1983-07-01

Investigations performed in 172 patients have shown that the state of the myocardium (such parameters as the heart volume, degree of lung hypertension, end-diastolic pressure in the right and left ventricles) is of great importance in pathogenesis of the development of acute heart failure in the early postoperative period in patients with mitral stenosis of the IIIrd and IVth stage of the blood circulation insufficiency.

Local irrigation management institutions mediate changes driven by external policy and market pressures in Nepal and Thailand.

PubMed

Bastakoti, Ram C; Shivakoti, Ganesh P; Lebel, Louis

2010-09-01

This article assesses the role of local institutions in managing irrigation water use. Fifty irrigation systems in each country were studied in Nepal and Thailand to compare the influence of local institutions on performance of irrigation systems amid changes in external policy and market pressures. Nepal's new irrigation policy after the re-instatement of multiparty democracy in 1990 emphasized participatory irrigation management transferring the management responsibility from state authorities to water users. The water user associations of traditional farmer-managed irrigation systems were formally recognized by requiring registration with related state authorities. In Thailand also government policies encouraged people's participation in irrigation management. Today water users are directly involved in management of even some large irrigation systems at the level of tertiary canals. Traditional communal irrigation systems in northern Thailand received support for system infrastructure improvement but have faced increased interference from government. In Thailand market development supported diversification in farming practices resulting in increased areas under high water-demanding commercial crops in the dry season. In contrast, the command areas of most irrigation systems in Nepal include cereal-based subsistence farming with only one-third having commercial farming. Cropping intensities are higher in Nepal than in Thailand reflecting, in part, differences in availability of land and management. In both countries local institutions play an important role in maintaining the performance of irrigation systems as external drivers and local contexts change. Local institutions have provided alternative options for irrigation water use by mediating external pressures.

THE PRESSURE OF AGING

PubMed Central

AlGhatrif, Majd; Wang, Mingyi; Fedorova, Olga V.; Bagrov, Alexei Y.; Lakatta, Edward G.

2016-01-01

Significant hemodynamic changes ensue with aging, leading to an ever-growing epidemic of hypertension. Alterations in central arterial properties play a major role in these hemodynamic changes. These alterations are characterized by an initial decline in aortic distensibility and a rise of diastolic blood pressure, followed by a sharp increase in pulse wave velocity (PWV), and a rise in pulse pressure (PP) beyond the sixth decade. However, the trajectories of PWV and PP diverge with advancing age, more profoundly in men than women, likely reflecting the more pronounced aortic dilatation in men. There is an increased prevalence of salt-sensitive hypertension with advancing age, that is, in part, mediated by marinobufagenin, an endogenous sodium pump ligand, which is also linked to central arterial stiffness. Within the arterial wall, biomechanical and humoral changes are accompanied by significant biomolecular alterations producing a proinflammatory state, in which activation of angiotensin II signaling plays a pivotal role. This proinflammatory state is in origin a reparatory response to a damaged arterial wall under a pulsatile injury. However the same reparatory process results in fibrosis, which in turn worsens arterial stiffness and produce more pulsatile hemodynamics; this relationship between the pulsatile damage and proinflammatory state is best described as a feed-forward loop. Effective efforts to counter the surging epidemic of hypertension with the aging of our population should be aimed at revealing early, pre-clinical hemodynamic and arterial wall alterations, and develop interventions that halt these processes before they reach the stage the medical community defined as “disease”. PMID:27884238

Fetal Programming and Cardiovascular Pathology

PubMed Central

Alexander, Barbara T.; Dasinger, John Henry; Intapad, Suttira

2016-01-01

Low birth weight serves as a crude proxy for impaired growth during fetal life and indicates a failure for the fetus to achieve its full growth potential. Low birth weight can occur in response to numerous etiologies that include complications during pregnancy, poor prenatal care, parental smoking, maternal alcohol consumption or stress. Numerous epidemiological and experimental studies demonstrate that birth weight is inversely associated with blood pressure and coronary heart disease. Sex and age impact the developmental programming of hypertension. In addition, impaired growth during fetal life also programs enhanced vulnerability to a secondary insult. Macrosomia, which occurs in response to maternal obesity, diabetes and excessive weight gain during gestation, is also associated with increased cardiovascular risk. Yet, the exact mechanisms that permanently change the structure, physiology and endocrine health of an individual across their lifespan following altered growth during fetal life are not entirely clear. Transmission of increased risk from one generation to the next in the absence of an additional prenatal insult indicates an important role for epigenetic processes. Experimental studies also indicate that the sympathetic nervous system, the renin angiotensin system, increased production of oxidative stress and increased endothelin play an important role in the developmental programming of blood pressure in later life. Thus, this review will highlight how adverse influences during fetal life and early development program an increased risk for cardiovascular disease including high blood pressure and provide an overview of the underlying mechanisms that contribute to the fetal origins of cardiovascular pathology. PMID:25880521

Effect of increased venous pressure on renal hemodynamics.

DOT National Transportation Integrated Search

1962-10-01

Conflicting evidence exists in regard to the effects of increased venous pressure on renal hemodynamics. Experiments to clarify its role were carried on twenty-eight intact innervated or isolated perfused dog kidneys. Findings indicate the absence of...

Augmented endothelial l-arginine transport ameliorates pressure-overload-induced cardiac hypertrophy.

PubMed

Rajapakse, Niwanthi W; Johnston, Tamara; Kiriazis, Helen; Chin-Dusting, Jaye P; Du, Xiao-Jun; Kaye, David M

2015-07-01

What is the central question of this study? What is the potential role of endothelial NO production via overexpression of the l-arginine transporter, CAT1, as a mitigator of cardiac hypertrophy? What is the main finding and its importance? Augmentation of endothelium-specific l-arginine transport via CAT1 can attenuate pressure-overload-dependent cardiac hypertrophy and fibrosis. Our findings support the conclusion that interventions that improve endothelial l-arginine transport may provide therapeutic utility in the setting of myocardial hypertrophy. Such modifications may be introduced by exercise training or locally delivered gene therapy, but further experimental and clinical studies are required. Endothelial dysfunction has been postulated to play a central role in the development of cardiac hypertrophy, probably as a result of reduced NO bioavailability. We tested the hypothesis that increased endothelial NO production, mediated by increased l-arginine transport, could attenuate pressure-overload-induced cardiac hypertrophy. Echocardiography and blood pressure measurements were performed 15 weeks after transverse aortic constriction (TAC) in wild-type (WT) mice (n = 12) and in mice with endothelium-specific overexpression of the l-arginine transporter, CAT1 (CAT+; n = 12). Transverse aortic constriction induced greater increases in heart weight to body weight ratio in WT (by 47%) than CAT+ mice (by 25%) compared with the respective controls (P ≤ 0.05). Likewise, the increase in left ventricular wall thickness induced by TAC was significantly attenuated in CAT+ mice (P = 0.05). Cardiac collagen type I mRNA expression was greater in WT mice with TAC (by 22%; P = 0.03), but not in CAT+ mice with TAC, compared with the respective controls. Transverse aortic constriction also induced lesser increases in β-myosin heavy chain mRNA expression in CAT+ mice compared with WT (P ≤ 0.05). Left ventricular systolic pressure after TAC was 36 and 39% greater in WT and CAT+ mice, respectively, compared with the respective controls (P ≤ 0.001). Transverse aortic constriction had little effect on left ventricular end-diastolic pressure in both genotypes. Taken together, these data indicate that augmenting endothelial function by overexpression of l-arginine transport can attenuate pressure-overload-induced cardiac hypertrophy. © 2015 The Authors. Experimental Physiology © 2015 The Physiological Society.

Reynolds-Averaged Turbulence Model Assessment for a Highly Back-Pressured Isolator Flowfield

NASA Technical Reports Server (NTRS)

Baurle, Robert A.; Middleton, Troy F.; Wilson, L. G.

2012-01-01

The use of computational fluid dynamics in scramjet engine component development is widespread in the existing literature. Unfortunately, the quantification of model-form uncertainties is rarely addressed with anything other than sensitivity studies, requiring that the computational results be intimately tied to and calibrated against existing test data. This practice must be replaced with a formal uncertainty quantification process for computational fluid dynamics to play an expanded role in the system design, development, and flight certification process. Due to ground test facility limitations, this expanded role is believed to be a requirement by some in the test and evaluation community if scramjet engines are to be given serious consideration as a viable propulsion device. An effort has been initiated at the NASA Langley Research Center to validate several turbulence closure models used for Reynolds-averaged simulations of scramjet isolator flows. The turbulence models considered were the Menter BSL, Menter SST, Wilcox 1998, Wilcox 2006, and the Gatski-Speziale explicit algebraic Reynolds stress models. The simulations were carried out using the VULCAN computational fluid dynamics package developed at the NASA Langley Research Center. A procedure to quantify the numerical errors was developed to account for discretization errors in the validation process. This procedure utilized the grid convergence index defined by Roache as a bounding estimate for the numerical error. The validation data was collected from a mechanically back-pressured constant area (1 2 inch) isolator model with an isolator entrance Mach number of 2.5. As expected, the model-form uncertainty was substantial for the shock-dominated, massively separated flowfield within the isolator as evidenced by a 6 duct height variation in shock train length depending on the turbulence model employed. Generally speaking, the turbulence models that did not include an explicit stress limiter more closely matched the measured surface pressures. This observation is somewhat surprising, given that stress-limiting models have generally been developed to better predict shock-separated flows. All of the models considered also failed to properly predict the shape and extent of the separated flow region caused by the shock boundary layer interactions. However, the best performing models were able to predict the isolator shock train length (an important metric for isolator operability margin) to within 1 isolator duct height.

Congestion of mastoid mucosa and influence on middle ear pressure - Effect of retroauricular injection of adrenaline.

PubMed

Fooken Jensen, Pernille Vita; Gaihede, Michael

2016-10-01

Micro-CT scanning of temporal bones has revealed numerous retroauricular microchannels, which connect the outer bone surface directly to the underlying mastoid air cells. Their structure and dimensions have suggested a separate vascular supply to the mastoid mucosa, which may play a role in middle ear (ME) pressure regulation. This role may be accomplished by changes in the mucosa congestion resulting in volumetric changes, which ultimately affect the pressure of the enclosed ME gas pocket (Boyle's law). Further, such mucosa congestion may be susceptible to α-adrenergic stimulation similar to the mucosa of the nose. The purpose of our study was to investigate these hypotheses by recording the ME pressure in response to adrenergic stimulation administered by retroauricular injections at the surface of the microchannels. In a group of 20 healthy adults we measured the ME pressure by tympanometry initially in the sitting position, and then in the supine position over a 5 min period with 30 s intervals. In each subject, the study included 1) a control reference experiment with no intervention, 2) a control experiment with subcutaneously retroauricular injection of 1 ml isotonic NaCl solution, and 3) a test experiment with subcutaneously retroauricular injection of 1 ml NaCl-adrenaline solution. In both control experiments the ME pressure displayed an immediate increase in response to changing body position; this pressure increase remained stable for the entire period up to five minutes. In the test experiments the ME pressure also showed an initial pressure increase, but it was followed by a distinct significant pressure decrease with a maximum after 90 s. The test group was injected with both a 5 and 10% adrenaline solution, but the responses appeared similar for the two concentrations. Subcutaneous retroauricular injection of adrenaline caused a significant pressure decrease in ME pressure compared with control ears. This may be explained by the microchannels conveying the adrenaline to the underlying mastoid mucosa, where it may result in a vascular constriction and decongestion, ultimately resulting in a ME pressure decrease. These findings suggest that the microchannels contain vascular connections to the mastoid mucosa, and that the mastoid mucosa is susceptible to vasoactive mediators, which may play a role in ME pressure regulation. Further anatomical and physiological experiments should be carried out to confirm these suggestions including pharmacological interactions with the mastoid mucosa. Copyright © 2016 Elsevier B.V. All rights reserved.

The Role of Lobbyists in the Defense Budget and Procurement Process.

DTIC Science & Technology

1986-05-15

selfish or misguided methods used by pressure groups led to legislation that lined the pockets of the pressure group or imposed the group’s 2 standards on...corporations, unions, and other strong pressure group organizations. 3 It must also be remembered that this legislation primarily affects the Executive...purposes in mind. Common Cause, the most active pressure group advocating reform on this issue, argued that companies spend large sums of money to

Susceptibility to social pressure following ventromedial prefrontal cortex damage.

PubMed

Chen, Kuan-Hua; Rusch, Michelle L; Dawson, Jeffrey D; Rizzo, Matthew; Anderson, Steven W

2015-11-01

Social pressure influences human behavior including risk taking, but the psychological and neural underpinnings of this process are not well understood. We used the human lesion method to probe the role of ventromedial prefrontal cortex (vmPFC) in resisting adverse social pressure in the presence of risk. Thirty-seven participants (11 with vmPFC damage, 12 with brain damage outside the vmPFC and 14 without brain damage) were tested in driving simulator scenarios requiring left-turn decisions across oncoming traffic with varying time gaps between the oncoming vehicles. Social pressure was applied by a virtual driver who honked aggressively from behind. Participants with vmPFC damage were more likely to select smaller and potentially unsafe gaps under social pressure, while gap selection by the comparison groups did not change under social pressure. Participants with vmPFC damage also showed prolonged elevated skin conductance responses (SCR) under social pressure. Comparison groups showed similar initial elevated SCR, which then declined prior to making left-turn decisions. The findings suggest that the vmPFC plays an important role in resisting explicit and immediately present social pressure with potentially negative consequences. The vmPFC appears to contribute to the regulation of emotional responses and the modulation of decision making to optimize long-term outcomes. © The Author (2015). Published by Oxford University Press. For Permissions, please email: journals.permissions@oup.com.

Autonomic neural control of dynamic cerebral autoregulation in humans

NASA Technical Reports Server (NTRS)

Zhang, Rong; Zuckerman, Julie H.; Iwasaki, Kenichi; Wilson, Thad E.; Crandall, Craig G.; Levine, Benjamin D.

2002-01-01

BACKGROUND: The purpose of the present study was to determine the role of autonomic neural control of dynamic cerebral autoregulation in humans. METHODS AND RESULTS: We measured arterial pressure and cerebral blood flow (CBF) velocity in 12 healthy subjects (aged 29+/-6 years) before and after ganglion blockade with trimethaphan. CBF velocity was measured in the middle cerebral artery using transcranial Doppler. The magnitude of spontaneous changes in mean blood pressure and CBF velocity were quantified by spectral analysis. The transfer function gain, phase, and coherence between these variables were estimated to quantify dynamic cerebral autoregulation. After ganglion blockade, systolic and pulse pressure decreased significantly by 13% and 26%, respectively. CBF velocity decreased by 6% (P<0.05). In the very low frequency range (0.02 to 0.07 Hz), mean blood pressure variability decreased significantly (by 82%), while CBF velocity variability persisted. Thus, transfer function gain increased by 81%. In addition, the phase lead of CBF velocity to arterial pressure diminished. These changes in transfer function gain and phase persisted despite restoration of arterial pressure by infusion of phenylephrine and normalization of mean blood pressure variability by oscillatory lower body negative pressure. CONCLUSIONS: These data suggest that dynamic cerebral autoregulation is altered by ganglion blockade. We speculate that autonomic neural control of the cerebral circulation is tonically active and likely plays a significant role in the regulation of beat-to-beat CBF in humans.

Understanding motivation for substance use treatment: the role of social pressure during the transition to adulthood.

PubMed

Goodman, Ilana; Peterson-Badali, Michele; Henderson, Joanna

2011-06-01

Research has shown that social pressure is related to treatment motivation and plays an important role in treatment engagement in adults with problematic substance use. Despite the shifts in autonomy and decision-making in emerging adulthood, the factors affecting treatment motivation (e.g., readiness to comply with treatment) during this period have been largely ignored. In this cross sectional study, 134 youth (83 males and 51 females) presenting to an outpatient substance abuse program completed questionnaires regarding substance use history, mental health, social pressure to reduce use and enter treatment, and treatment motivation. Age was positively related to identification of internal reasons for seeking treatment and negatively related to external coercive social pressures as a motivator for treatment. Peer pressure accounted for significant variance in Identified (e.g., personal choice and commitment to the program) and Introjected (e.g., guilt about continued substance use) treatment motivation. Family pressure was related only to External treatment motivation when peer pressure was considered in the regression model. These results highlight the importance of emerging adult peers as motivators of youths' treatment seeking. Limitations, directions for future research and treatment implications are discussed. Crown Copyright © 2011. Published by Elsevier Ltd. All rights reserved.

Role of parietal pericardium in acute, severe mitral regurgitation in dogs.

PubMed

Freeman, G L; LeWinter, M M

1984-07-01

Mitral regurgitation (MR) resulting from acute disruption of the mitral valve apparatus leads to serious hemodynamic sequelae. The lesion produces major elevation of left atrial (LA) and pulmonary artery pressures and decreases forward cardiac output. Clinical studies have shown hemodynamic patterns in acute MR similar to those seen in constrictive pericardial disease, suggesting that the pericardium serves to importantly limit cardiac filling in this condition. This hypothesis has not been tested in an animal model in which the intrapericardial pressure can be directly measured. In the present study intrapericardial and intracardiac pressures were measured in 8 dogs before and after the production of acute MR. After production of MR, mean LA pressure increased from 8 +/- 3 to 20 +/- 7 mm Hg (p = 0.004) and the peak LA V wave averaged 31 +/- 13 mm Hg. Mean right atrial pressure increased slightly, from 4 +/- 2 to 5 +/- 1 mm Hg (p less than 0.008). Intrapericardial pressure increased in each dog, but the increment was invariably small (1 +/- 2 to 3 +/- 2 mm Hg, p = 0.001) and there was no tendency to equalization of pressure between right- and left-sided cardiac chambers. Thus, the role of the pericardium in the immediate hemodynamic response to acute, severe MR is minor.

Tissue-specific expression of transgenic secreted ACE in vasculature can restore normal kidney functions, but not blood pressure, of Ace-/- mice.

PubMed

Chattopadhyay, Saurabh; Kessler, Sean P; Colucci, Juliana Almada; Yamashita, Michifumi; Senanayake, Preenie deS; Sen, Ganes C

2014-01-01

Angiotensin-converting enzyme (ACE) regulates normal blood pressure and fluid homeostasis through its action in the renin-angiotensin-system (RAS). Ace-/- mice are smaller in size, have low blood pressure and defective kidney structure and functions. All of these defects are cured by transgenic expression of somatic ACE (sACE) in vascular endothelial cells of Ace-/- mice. sACE is expressed on the surface of vascular endothelial cells and undergoes a natural cleavage secretion process to generate a soluble form in the body fluids. Both the tissue-bound and the soluble forms of ACE are enzymatically active, and generate the vasoactive octapeptide Angiotensin II (Ang II) with equal efficiency. To assess the relative physiological roles of the secreted and the cell-bound forms of ACE, we expressed, in the vascular endothelial cells of Ace-/- mice, the ectodomain of sACE, which corresponded to only the secreted form of ACE. Our results demonstrated that the secreted form of ACE could normalize kidney functions and RAS integrity, growth and development of Ace-/- mice, but not their blood pressure. This study clearly demonstrates that the secreted form of ACE cannot replace the tissue-bound ACE for maintaining normal blood pressure; a suitable balance between the tissue-bound and the soluble forms of ACE is essential for maintaining all physiological functions of ACE.

Applying large datasets to developing a better understanding of air leakage measurement in homes

DOE PAGES

Walker, I. S.; Sherman, M. H.; Joh, J.; ...

2013-03-01

Air tightness is an important property of building envelopes. It is a key factor in determining infiltration and related wall-performance properties such as indoor air quality, maintainability and moisture balance. Air leakage in U.S. houses consumes roughly 1/3 of the HVAC energy but provides most of the ventilation used to control IAQ. There are several methods for measuring air tightness that may result in different values and sometimes quite different uncertainties. The two main approaches trade off bias and precision errors and thus result indifferent outcomes for accuracy and repeatability. To interpret results from the two approaches, various questions needmore » to be addressed, such as the need to measure the flow exponent, the need to make both pressurization and depressurization measurements and the role of wind in determining the accuracy and precision of the results. This article uses two large datasets of blower door measurements to reach the following conclusions. For most tests the pressure exponent should be measured but for wind speeds greater than 6 m/s a fixed pressure exponent reduces experimental error. The variability in reported pressure exponents is mostly due to changes in envelope leakage characteristics. Finally, it is preferable to test in both pressurization and depressurization modes due to significant differences between the results in these two modes.« less

Tissue-Specific Expression of Transgenic Secreted ACE in Vasculature Can Restore Normal Kidney Functions, but Not Blood Pressure, of Ace-/- Mice

PubMed Central

Chattopadhyay, Saurabh; Kessler, Sean P.; Colucci, Juliana Almada; Yamashita, Michifumi; Senanayake, Preenie deS; Sen, Ganes C.

2014-01-01

Angiotensin-converting enzyme (ACE) regulates normal blood pressure and fluid homeostasis through its action in the renin-angiotensin-system (RAS). Ace-/- mice are smaller in size, have low blood pressure and defective kidney structure and functions. All of these defects are cured by transgenic expression of somatic ACE (sACE) in vascular endothelial cells of Ace-/- mice. sACE is expressed on the surface of vascular endothelial cells and undergoes a natural cleavage secretion process to generate a soluble form in the body fluids. Both the tissue-bound and the soluble forms of ACE are enzymatically active, and generate the vasoactive octapeptide Angiotensin II (Ang II) with equal efficiency. To assess the relative physiological roles of the secreted and the cell-bound forms of ACE, we expressed, in the vascular endothelial cells of Ace-/- mice, the ectodomain of sACE, which corresponded to only the secreted form of ACE. Our results demonstrated that the secreted form of ACE could normalize kidney functions and RAS integrity, growth and development of Ace-/- mice, but not their blood pressure. This study clearly demonstrates that the secreted form of ACE cannot replace the tissue-bound ACE for maintaining normal blood pressure; a suitable balance between the tissue-bound and the soluble forms of ACE is essential for maintaining all physiological functions of ACE. PMID:24475296

Extracellular signal-regulated kinase (ERK) activation preserves cardiac function in pressure overload induced hypertrophy.

PubMed

Mutlak, Michael; Schlesinger-Laufer, Michal; Haas, Tali; Shofti, Rona; Ballan, Nimer; Lewis, Yair E; Zuler, Mor; Zohar, Yaniv; Caspi, Lilac H; Kehat, Izhak

2018-05-24

Chronic pressure overload and a variety of mediators induce concentric cardiac hypertrophy. When prolonged, cardiac hypertrophy culminates in decreased myocardial function and heart failure. Activation of the extracellular signal-regulated kinase (ERK) is consistently observed in animal models of hypertrophy and in human patients, but its role in the process is controversial. We generated transgenic mouse lines with cardiomyocyte restricted overexpression of intrinsically active ERK1, which similar to the observations in hypertrophy is phosphorylated on both the TEY and the Thr207 motifs and is overexpressed at pathophysiological levels. The activated ERK1 transgenic mice developed a modest adaptive hypertrophy with increased contractile function and without fibrosis. Following induction of pressure-overload, where multiple pathways are stimulated, this activation did not further increase the degree of hypertrophy but protected the heart through a decrease in the degree of fibrosis and maintenance of ventricular contractile function. The ERK pathway acts to promote a compensated hypertrophic response, with enhanced contractile function and reduced fibrosis. The activation of this pathway may be a therapeutic strategy to preserve contractile function when the pressure overload cannot be easily alleviated. The inhibition of this pathway, which is increasingly being used for cancer therapy on the other hand, should be used with caution in the presence of pressure-overload. Copyright © 2017. Published by Elsevier B.V.

Are clusters important in understanding the mechanisms in atmospheric pressure ionization? Part 1: Reagent ion generation and chemical control of ion populations.

PubMed

Klee, Sonja; Derpmann, Valerie; Wißdorf, Walter; Klopotowski, Sebastian; Kersten, Hendrik; Brockmann, Klaus J; Benter, Thorsten; Albrecht, Sascha; Bruins, Andries P; Dousty, Faezeh; Kauppila, Tiina J; Kostiainen, Risto; O'Brien, Rob; Robb, Damon B; Syage, Jack A

2014-08-01

It is well documented since the early days of the development of atmospheric pressure ionization methods, which operate in the gas phase, that cluster ions are ubiquitous. This holds true for atmospheric pressure chemical ionization, as well as for more recent techniques, such as atmospheric pressure photoionization, direct analysis in real time, and many more. In fact, it is well established that cluster ions are the primary carriers of the net charge generated. Nevertheless, cluster ion chemistry has only been sporadically included in the numerous proposed ionization mechanisms leading to charged target analytes, which are often protonated molecules. This paper series, consisting of two parts, attempts to highlight the role of cluster ion chemistry with regard to the generation of analyte ions. In addition, the impact of the changing reaction matrix and the non-thermal collisions of ions en route from the atmospheric pressure ion source to the high vacuum analyzer region are discussed. This work addresses such issues as extent of protonation versus deuteration, the extent of analyte fragmentation, as well as highly variable ionization efficiencies, among others. In Part 1, the nature of the reagent ion generation is examined, as well as the extent of thermodynamic versus kinetic control of the resulting ion population entering the analyzer region.

Cerebral Hypoperfusion Precedes Nausea During Centrifugation

NASA Technical Reports Server (NTRS)

Serrador, Jorge M.; Schlegel, Todd T.; Black, F. Owen; Wood, Scott J.

2004-01-01

Nausea and motion sickness are important operational concerns for aviators and astronauts. Understanding underlying mechanisms associated with motion sickness may lead to new treatments. The goal of this work was to determine if cerebral blood flow changes precede the development of nausea in motion sick susceptible subjects. Cerebral flow velocity in the middle cerebral artery (transcranial Doppler), blood pressure (Finapres) and end-tidal CO2 were measured while subjects were rotated on a centrifuge (250 degrees/sec). Following 5 min of rotation, subjects were translated 0.504 m off-center, creating a +lGx centripetal acceleration in the nasal-occipital plane. Ten subjects completed the protocol without symptoms while 5 developed nausea (4 while 6ff-center and 1 while rotating on-center). Prior to nausea, subjects had significant increases in blood pressure (+13plus or minus 3 mmHg, P less than 0.05) and cerebrovascular resistance (+46 plus or minus 17%, P less than 0.05) and decreases in cerebral flow velocity both in the second (-13 plus or minus 4%) and last minute (-22 plus or minus 5%) before symptoms (P less than 0.05). In comparison, controls demonstrated no change in blood pressure or cerebrovascular resistance in the last minute of off-center rotation and only a 7 plus or minus 2% decrease in cerebral flow velocity. All subjects had significant hypocapnia (-3.8 plus or minus 0.4 mmHg, P less than 0.05), however this hypocapnia could not fully explain the cerebral hypoperfusion associated with the development of nausea. These data indicate that reductions in cerebral blood flow precede the development of nausea. Further work is necessary to determine what role cerebral hypoperfusion plays in motion sickness and whether cerebral hypoperfusion can be used to predict the development of nausea in susceptible individuals.

Role of vortices in growth of microbubbles at mitral mechanical heart valve closure.

PubMed

Rambod, Edmond; Beizai, Masoud; Sahn, David J; Gharib, Morteza

2007-07-01

This study is aimed at refining our understanding of the role of vortex formation at mitral mechanical heart valve (MHV) closure and its association with the high intensity transient signals (HITS) seen in echocardiographic studies with MHV recipients. Previously reported numerical results described a twofold process leading to formation of gas-filled microbubbles in-vitro: (1) nucleation and (2) growth of micron size bubbles. The growth itself consists of two processes: (a) diffusion and (b) sudden pressure drop due to valve closure. The role of diffusion has already been shown to govern the initial growth of nuclei. Pressure drop at mitral MHV closure may be attributed to other phenomena such as squeezed flow, water hammer and primarily, vortex cavitation. Mathematical analysis of vortex formation at mitral MHV closure revealed that a closing velocity of approximately 12 m/s can induce a strong regurgitant vortex which in return can instigate a local pressure drop of about 0.9 atm. A 2D experimental model of regurgitant flows was used to substantiate the impact of vortices. At simulated flow and pressure conditions, a regurgitant vortex was observed to drastically enlarge micron size hydrogen bubbles at its core.

Development of Nanoparticle-Stabilized Foams to Improve Performance of Water-less Hydraulic Fracturing

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

Prodanovic, Masa; Johnston, Keith P.

We have successfully created ultra dry carbon-dioxide-in-water and nitrogen-in-water foams (with water content down to 2-5% range), that are remarkably stable at high temperatures (up to 120 deg, C) and pressures (up to 3000psi) and viscous enough (100-200 cP tunable range) to carry proppant. Two generations of these ultra-dry foams have been developed; they are stabilized either with a synergy of surfactants and nanoparticle, or just with viscoelastic surfactants that viscosify the aqueous phase. Not only does this reduce water utilization and disposal, but it minimizes fluid blocking of hydrocarbon production. Further, the most recent development shows successful use ofmore » environmentally friendly surfactants at high temperature and pressure. We pay special attention to the role of nanoparticles in stabilization of the foams, specifically for high salinity brines. The preliminary numerical simulation for which shows they open wider fractures with shorter half-length and require less clean-up due to minimal water use. We also tested the stability and sand carrying properties of these foams at high pressure, room temperature conditions in sapphire cell. We performed on a preliminary numerical investigation of applicability for improved oil recovery applications. The applicability was evaluated by running multiphase flow injection simulations in a case-study oil reservoir. The results of this research thus expand the options available to operators for hydraulic fracturing and can simplify the design and field implementation of foamed fracturing fluids.« less

Recurrent laryngeal nerve alterations in developing spontaneously hypertensive rats.

PubMed

da Silva, Greice Anne Rodrigues; Mendes, Vania Alice de Aguiar; Genari, Adriana Borges; Castania, Jaci Ayrton; Salgado, Hélio Cesar; Fazan, Valéria Paula Sassoli

2016-01-01

It is well known that the recurrent laryngeal nerve not only innervates the larynx but also contains baroreceptor fibers, as demonstrated by physiological studies. Because hypertension has a negative impact on both peripheral nerve morphology and the baroreflex, we investigated the recurrent laryngeal nerve morphological alterations related to the development of hypertension. We compared morphological and morphometric aspects of different segments of the recurrent laryngeal nerve in male and female spontaneously hypertensive rats in different ages: 5, 8, and 20 weeks (n = 6 per group). Blood pressure and heart rate were recorded in anesthetized animals, followed by removal of the right and left recurrent laryngeal nerves for epoxy resin embedding and light microscopy analysis. Computer software was used for morphometric analysis. The blood pressure was significantly higher in 20-week-old animals compared to those at 5 weeks. Body weight increased significantly with age, as did the nerve fascicles. For the myelinated fibers and respective axons, there was a reduction of fiber size, more evident on the axon, associated with a reduction of the small myelinated fibers percentage in animals with high blood pressure. Also, 20-week-old animals showed a significant reduction of the blood vessel percentage of occupancy compared to younger ages. No differences were observed between genders. Hypertension development impaired axon growth, affecting mainly the small myelinated fibers. Males and females were affected equally. The alterations of the endoneural blood vessels probably played an important role on the small fibers alterations. © 2015 The American Laryngological, Rhinological and Otological Society, Inc.

Prenatal exposure to angiotensin II increases blood pressure and decreases salt sensitivity in rats.

PubMed

Svitok, Pavel; Senko, Tomas; Panakova, Zuzana; Olexova, Lucia; Krskova, Lucia; Okuliarova, Monika; Zeman, Michal

2017-01-01

Renin angiotensin aldosterone system (RAAS) plays an essential role in the homeostatic control of arterial blood pressure, perfusion of tissues, and control of extracellular fluid. Its components are highly expressed in the developing kidney, general vasculature, brain, and heart. A modified intrauterine environment alters mechanisms controlling blood pressure (BP) and can lead to hypertension in the adult offspring and developmentally programmed RAAS can be involved in this process. There are very little data about the effects of increased angiotensin II (Ang II) concentrations during pregnancy on in utero development of the fetus. In our study, we administered Ang II to pregnant female rats via osmotic mini-pumps and evaluated the postnatal development and BP control in the offspring. To estimate possible developmental changes in sensitivity to salt, we exposed the offspring to a diet with increased salt content and measured plasma aldosterone levels and plasma renin activity. Increased Ang II during pregnancy raised BP in the offspring; however, salt sensitivity was decreased in comparison to controls. Relative weight of the left ventricle was decreased in the offspring prenatally exposed to Ang II, while relative kidney weight was reduced only in female offspring. Prenatal treatment led to increased aldosterone levels and decreased plasma renin activity, suggesting a complex physiological response. Our results suggest that conditions leading to upregulation of RAAS during pregnancy can influence the cardiovascular system of the fetus and have a long-term impact on the offspring's health.

Propagule pressure governs establishment of an invasive herb

NASA Astrophysics Data System (ADS)

Ramula, Satu; Jauni, Miia; van Ooik, Tapio

2015-10-01

The success of plant invasions may be limited by the availability of propagules and/or of suitable microsites, with microsite availability being affected by, for example, disturbance and interspecific competition. A mechanistic understanding of the contributions of propagule pressure and microsite limitation to plant invasions is therefore required to minimise future invasions. Here, we investigated the relative roles of propagule pressure, the availability of microsites, and their interaction on the establishment of an invasive herb, Lupinus polyphyllus, in two geographic regions representing different climate and growth conditions in Finland (a more productive southern region and a harsher central region). We carried out a field experiment in 14 L. polyphyllus populations, in which we manipulated both propagule pressure and disturbance. In a complementary greenhouse experiment, we manipulated propagule pressure and interspecific competition. Seedling establishment of L. polyphyllus was higher in the more productive southern region than in the harsher central region. The number of L. polyphyllus seedlings increased with increasing propagule pressure regardless of disturbance or interspecific competition. However, the number of L. polyphyllus seedlings per sown seed (relative establishment) tended to decrease with increasing propagule pressure, indicating that the positive effect of propagule pressure on early invasion is partially counteracted by density-dependent mortality at high seed densities. Our results highlight the dominant role of propagule pressure over disturbance and interspecific competition in the establishment of L. polyphyllus, suggesting that the early stage of invasion is limited by the availability of propagules rather than the availability of suitable microsites.

[Experimental evaluation of the role of the coronary sinus pressure in the regulation of coronary return volume via the coronary sinus. Surgical considerations in atrio-pulmonary diversion procedures].

PubMed

Fantidis, P; Fernández Ruiz, M A; Madero Jarabo, R; Moreno Granados, F; Cordovilla Zurdo, G; Sanz Galeote, E

1990-11-01

In order to find out the validity of the vascular waterfall mechanism in coronary venous circulation, the role of coronary sinus pressure in the regulation of coronary return volume via the coronary sinus is studied in healthy animals. An experimental model of pressure regulation in the coronary sinus was prepared, and aortic pressure, EKG and the cardiac output (measured by thermodilution) were recorded. The return volume via the coronary sinus was measured at coronary sinus pressure of 10 or less, 15, 20, and 25 mmHg or more, for a total of 36 determinations. Increased coronary sinus pressure did not produce significant changes in aortic pressure, heart rate, cardiac index or coronary return volume via coronary sinus. When coronary sinus pressure was 25 mmHg or more, there was a significant decline in the average of coronary return volume via coronary sinus. Nevertheless, stepwise variant regression showed that the coronary sinus pressure per se does not condition the volume of coronary return via the coronary sinus. Our results suggest that in the healthy animals, the vascular waterfall mechanism in coronary venous circulation is not valid. Our results suggest that in the correction of congenital cardiac malformations using atriopulmonary anastomosis procedures, employing techniques that ensure coronary sinus drainage into the left atrium, in order to avoid the hemodynamic repercussions attributable to the vascular waterfall mechanism, is not justified.

Towards understanding of Nipah virus attachment protein assembly and the role of protein affinity and crowding for membrane curvature events.

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

Stachowiak, Jeanne C.; Hayden, Carl C.; Negrete, Oscar.

2013-10-01

Pathogenic viruses are a primary threat to our national security and to the health and economy of our world. Effective defense strategies to combat viral infection and spread require the development of understanding of the mechanisms that these pathogens use to invade the host cell. We present in this report results of our research into viral particle recognition and fusion to cell membranes and the role that protein affinity and confinement in lipid domains plays in membrane curvature in cellular fusion and fission events. Herein, we describe 1) the assembly of the G attachment protein of Nipah virus using pointmore » mutation studies to define its role in viral particle fusion to the cell membrane, 2) how lateral pressure of membrane bound proteins induce curvature in model membrane systems, and 3) the role of membrane curvature in the selective partitioning of molecular receptors and specific affinity of associated proteins.« less

Peer Pressure and Tobacco Smoking among Undergraduate Students of the University of Calabar, Cross River State

ERIC Educational Resources Information Center

Ukwayi, Joseph K.; Eja, Ojong Felix; Unwanede, Chibuzo C.

2012-01-01

Peer pressure becomes a perturbing and problematic phenomenon as children grow seeing their peers as role models. Peer pressure is a social institution that modifies adolescents' behaviours by making them indulge in risky behaviour such as smoking at early age. This phenomenon has indeed found its way into our tertiary institutions and among our…

Pressure-Induced Amorphization of Small Pore Zeolites—the Role of Cation-H2O Topology and Anti-glass Formation

PubMed Central

Chan Hwang, Gil; Joo Shin, Tae; Blom, Douglas A.; Vogt, Thomas; Lee, Yongjae

2015-01-01

Systematic studies of pressure-induced amorphization of natrolites (PIA) containing monovalent extra-framework cations (EFC) Li+, Na+, K+, Rb+, Cs+ allow us to assess the role of two different EFC-H2O configurations within the pores of a zeolite: one arrangement has H2O molecules (NATI) and the other the EFC (NATII) in closer proximity to the aluminosilicate framework. We show that NATI materials have a lower onset pressure of PIA than the NATII materials containing Rb and Cs as EFC. The onset pressure of amorphization (PA) of NATII materials increases linearly with the size of the EFC, whereas their initial bulk moduli (P1 phase) decrease linearly. Only Cs- and Rb-NAT reveal a phase separation into a dense form (P2 phase) under pressure. High-Angle Annular Dark Field Scanning Transmission Electron Microscopy (HAADF-STEM) imaging shows that after recovery from pressures near 25 and 20 GPa long-range ordered Rb-Rb and Cs-Cs correlations continue to be present over length scales up to 100 nm while short-range ordering of the aluminosilicate framework is significantly reduced—this opens a new way to form anti-glass structures. PMID:26455345

Low blood pressure in vegetarians: the possible role of potassium.

PubMed

Ophir, O; Peer, G; Gilad, J; Blum, M; Aviram, A

1983-05-01

Ninety-eight confirmed adult vegetarians were examined against a matched group of nonvegetarians living in the same urban environment in order to evaluate the prevalence of arterial hypertension. The average blood pressure was 126/77 for the vegetarians and 147/88 for the control group (p less than 0.05). Significantly lower blood pressure was found in every decade of age. Only 2% of the vegetarians had hypertension (higher than 160/95) as compared to 26% hypertensives in the nonvegetarians. These differences in blood pressure were maintained also when individuals with the same "relative weight" were compared. Family history of hypertension was similar in both groups. Analysis of factors such as coffee drinking and smoking did not favor reduced blood pressure among the vegetarian group. Sodium and potassium intake were evaluated from their ratios to creatinine in a single urine sample. It was evident that both groups excreted the same amounts of sodium, while potassium excretion was significantly higher in the vegetarians. In view of the increasing evidence that potassium plays an important role in the regulation of blood pressure it is concluded that the protective antihypertensive factor in the vegetarian diet is the presence of high amounts of potassium.

Pressure-Induced Amorphization of Small Pore Zeolites-the Role of Cation-H2O Topology and Anti-glass Formation.

PubMed

Chan Hwang, Gil; Joo Shin, Tae; Blom, Douglas A; Vogt, Thomas; Lee, Yongjae

2015-10-12

Systematic studies of pressure-induced amorphization of natrolites (PIA) containing monovalent extra-framework cations (EFC) Li(+), Na(+), K(+), Rb(+), Cs(+) allow us to assess the role of two different EFC-H2O configurations within the pores of a zeolite: one arrangement has H2O molecules (NATI) and the other the EFC (NATII) in closer proximity to the aluminosilicate framework. We show that NATI materials have a lower onset pressure of PIA than the NATII materials containing Rb and Cs as EFC. The onset pressure of amorphization (PA) of NATII materials increases linearly with the size of the EFC, whereas their initial bulk moduli (P1 phase) decrease linearly. Only Cs- and Rb-NAT reveal a phase separation into a dense form (P2 phase) under pressure. High-Angle Annular Dark Field Scanning Transmission Electron Microscopy (HAADF-STEM) imaging shows that after recovery from pressures near 25 and 20 GPa long-range ordered Rb-Rb and Cs-Cs correlations continue to be present over length scales up to 100 nm while short-range ordering of the aluminosilicate framework is significantly reduced-this opens a new way to form anti-glass structures.

Trans-ancestry genome-wide association study identifies 12 genetic loci influencing blood pressure and implicates a role for DNA methylation

PubMed Central

Drong, Alexander W; Abbott, James; Wahl, Simone; Tan, Sian-Tsung; Scott, William R; Campanella, Gianluca; Chadeau-Hyam, Marc; Afzal, Uzma; Ahluwalia, Tarunveer S; Bonder, Marc Jan; Chen, Peng; Dehghan, Abbas; Edwards, Todd L; Esko, Tõnu; Go, Min Jin; Harris, Sarah E; Hartiala, Jaana; Kasela, Silva; Kasturiratne, Anuradhani; Khor, Chiea-Chuen; Kleber, Marcus E; Li, Huaixing; Yu Mok, Zuan; Nakatochi, Masahiro; Sapari, Nur Sabrina; Saxena, Richa; Stewart, Alexandre F R; Stolk, Lisette; Tabara, Yasuharu; Teh, Ai Ling; Wu, Ying; Wu, Jer-Yuarn; Zhang, Yi; Aits, Imke; Da Silva Couto Alves, Alexessander; Das, Shikta; Dorajoo, Rajkumar; Hopewell, Jemma C; Kim, Yun Kyoung; Koivula, Robert W; Luan, Jian’an; Lyytikäinen, Leo-Pekka; Nguyen, Quang N; Pereira, Mark A; Postmus, Iris; Raitakari, Olli T; Bryan, Molly Scannell; Scott, Robert A; Sorice, Rossella; Tragante, Vinicius; Traglia, Michela; White, Jon; Yamamoto, Ken; Zhang, Yonghong; Adair, Linda S; Ahmed, Alauddin; Akiyama, Koichi; Asif, Rasheed; Aung, Tin; Barroso, Inês; Bjonnes, Andrew; Braun, Timothy R; Cai, Hui; Chang, Li-Ching; Chen, Chien-Hsiun; Cheng, Ching-Yu; Chong, Yap-Seng; Collins, Rory; Courtney, Regina; Davies, Gail; Delgado, Graciela; Do, Loi D; Doevendans, Pieter A; Gansevoort, Ron T; Gao, Yu-Tang; Grammer, Tanja B; Grarup, Niels; Grewal, Jagvir; Gu, Dongfeng; Wander, Gurpreet S; Hartikainen, Anna-Liisa; Hazen, Stanley L; He, Jing; Heng, Chew-Kiat; Hixson, James E; Hofman, Albert; Hsu, Chris; Huang, Wei; Husemoen, Lise L N; Hwang, Joo-Yeon; Ichihara, Sahoko; Igase, Michiya; Isono, Masato; Justesen, Johanne M; Katsuya, Tomohiro; Kibriya, Muhammad G; Kim, Young Jin; Kishimoto, Miyako; Koh, Woon-Puay; Kohara, Katsuhiko; Kumari, Meena; Kwek, Kenneth; Lee, Nanette R; Lee, Jeannette; Liao, Jiemin; Lieb, Wolfgang; Liewald, David C M; Matsubara, Tatsuaki; Matsushita, Yumi; Meitinger, Thomas; Mihailov, Evelin; Milani, Lili; Mills, Rebecca; Mononen, Nina; Müller-Nurasyid, Martina; Nabika, Toru; Nakashima, Eitaro; Ng, Hong Kiat; Nikus, Kjell; Nutile, Teresa; Ohkubo, Takayoshi; Ohnaka, Keizo; Parish, Sarah; Paternoster, Lavinia; Peng, Hao; Peters, Annette; Pham, Son T; Pinidiyapathirage, Mohitha J; Rahman, Mahfuzar; Rakugi, Hiromi; Rolandsson, Olov; Ann Rozario, Michelle; Ruggiero, Daniela; Sala, Cinzia F; Sarju, Ralhan; Shimokawa, Kazuro; Snieder, Harold; Sparsø, Thomas; Spiering, Wilko; Starr, John M; Stott, David J; Stram, Daniel O; Sugiyama, Takao; Szymczak, Silke; Tang, W H Wilson; Tong, Lin; Trompet, Stella; Turjanmaa, Väinö; Ueshima, Hirotsugu; Uitterlinden, André G; Umemura, Satoshi; Vaarasmaki, Marja; van Dam, Rob M; van Gilst, Wiek H; van Veldhuisen, Dirk J; Viikari, Jorma S; Waldenberger, Melanie; Wang, Yiqin; Wang, Aili; Wilson, Rory; Wong, Tien-Yin; Xiang, Yong-Bing; Yamaguchi, Shuhei; Ye, Xingwang; Young, Robin D; Young, Terri L; Yuan, Jian-Min; Zhou, Xueya; Asselbergs, Folkert W; Ciullo, Marina; Clarke, Robert; Deloukas, Panos; Franke, Andre; Franks, Paul W; Franks, Steve; Friedlander, Yechiel; Gross, Myron D; Guo, Zhirong; Hansen, Torben; Jarvelin, Marjo-Riitta; Jørgensen, Torben; Jukema, J Wouter; kähönen, Mika; Kajio, Hiroshi; Kivimaki, Mika; Lee, Jong-Young; Lehtimäki, Terho; Linneberg, Allan; Miki, Tetsuro; Pedersen, Oluf; Samani, Nilesh J; Sørensen, Thorkild I A; Takayanagi, Ryoichi; Toniolo, Daniela; Ahsan, Habibul; Allayee, Hooman; Chen, Yuan-Tsong; Danesh, John; Deary, Ian J; Franco, Oscar H; Franke, Lude; Heijman, Bastiaan T; Holbrook, Joanna D; Isaacs, Aaron; Kim, Bong-Jo; Lin, Xu; Liu, Jianjun; März, Winfried; Metspalu, Andres; Mohlke, Karen L; Sanghera, Dharambir K; Shu, Xiao-Ou; van Meurs, Joyce B J; Vithana, Eranga; Wickremasinghe, Ananda R; Wijmenga, Cisca; Wolffenbuttel, Bruce H W; Yokota, Mitsuhiro; Zheng, Wei; Zhu, Dingliang; Vineis, Paolo; Kyrtopoulos, Soterios A; Kleinjans, Jos C S; McCarthy, Mark I; Soong, Richie; Gieger, Christian; Scott, James

2016-01-01

We carried out a trans-ancestry genome-wide association and replication study of blood pressure phenotypes among up to 320,251 individuals of East Asian, European and South Asian ancestry. We find genetic variants at 12 new loci to be associated with blood pressure (P = 3.9 × 10−11 to 5.0 × 10−21). The sentinel blood pressure SNPs are enriched for association with DNA methylation at multiple nearby CpG sites, suggesting that, at some of the loci identified, DNA methylation may lie on the regulatory pathway linking sequence variation to blood pressure. The sentinel SNPs at the 12 new loci point to genes involved in vascular smooth muscle (IGFBP3, KCNK3, PDE3A and PRDM6) and renal (ARHGAP24, OSR1, SLC22A7 and TBX2) function. The new and known genetic variants predict increased left ventricular mass, circulating levels of NT-proBNP, and cardiovascular and all-cause mortality (P = 0.04 to 8.6 × 10−6). Our results provide new evidence for the role of DNA methylation in blood pressure regulation. PMID:26390057

Trans-ancestry genome-wide association study identifies 12 genetic loci influencing blood pressure and implicates a role for DNA methylation.

PubMed

Kato, Norihiro; Loh, Marie; Takeuchi, Fumihiko; Verweij, Niek; Wang, Xu; Zhang, Weihua; Kelly, Tanika N; Saleheen, Danish; Lehne, Benjamin; Leach, Irene Mateo; Drong, Alexander W; Abbott, James; Wahl, Simone; Tan, Sian-Tsung; Scott, William R; Campanella, Gianluca; Chadeau-Hyam, Marc; Afzal, Uzma; Ahluwalia, Tarunveer S; Bonder, Marc Jan; Chen, Peng; Dehghan, Abbas; Edwards, Todd L; Esko, Tõnu; Go, Min Jin; Harris, Sarah E; Hartiala, Jaana; Kasela, Silva; Kasturiratne, Anuradhani; Khor, Chiea-Chuen; Kleber, Marcus E; Li, Huaixing; Yu Mok, Zuan; Nakatochi, Masahiro; Sapari, Nur Sabrina; Saxena, Richa; Stewart, Alexandre F R; Stolk, Lisette; Tabara, Yasuharu; Teh, Ai Ling; Wu, Ying; Wu, Jer-Yuarn; Zhang, Yi; Aits, Imke; Da Silva Couto Alves, Alexessander; Das, Shikta; Dorajoo, Rajkumar; Hopewell, Jemma C; Kim, Yun Kyoung; Koivula, Robert W; Luan, Jian'an; Lyytikäinen, Leo-Pekka; Nguyen, Quang N; Pereira, Mark A; Postmus, Iris; Raitakari, Olli T; Bryan, Molly Scannell; Scott, Robert A; Sorice, Rossella; Tragante, Vinicius; Traglia, Michela; White, Jon; Yamamoto, Ken; Zhang, Yonghong; Adair, Linda S; Ahmed, Alauddin; Akiyama, Koichi; Asif, Rasheed; Aung, Tin; Barroso, Inês; Bjonnes, Andrew; Braun, Timothy R; Cai, Hui; Chang, Li-Ching; Chen, Chien-Hsiun; Cheng, Ching-Yu; Chong, Yap-Seng; Collins, Rory; Courtney, Regina; Davies, Gail; Delgado, Graciela; Do, Loi D; Doevendans, Pieter A; Gansevoort, Ron T; Gao, Yu-Tang; Grammer, Tanja B; Grarup, Niels; Grewal, Jagvir; Gu, Dongfeng; Wander, Gurpreet S; Hartikainen, Anna-Liisa; Hazen, Stanley L; He, Jing; Heng, Chew-Kiat; Hixson, James E; Hofman, Albert; Hsu, Chris; Huang, Wei; Husemoen, Lise L N; Hwang, Joo-Yeon; Ichihara, Sahoko; Igase, Michiya; Isono, Masato; Justesen, Johanne M; Katsuya, Tomohiro; Kibriya, Muhammad G; Kim, Young Jin; Kishimoto, Miyako; Koh, Woon-Puay; Kohara, Katsuhiko; Kumari, Meena; Kwek, Kenneth; Lee, Nanette R; Lee, Jeannette; Liao, Jiemin; Lieb, Wolfgang; Liewald, David C M; Matsubara, Tatsuaki; Matsushita, Yumi; Meitinger, Thomas; Mihailov, Evelin; Milani, Lili; Mills, Rebecca; Mononen, Nina; Müller-Nurasyid, Martina; Nabika, Toru; Nakashima, Eitaro; Ng, Hong Kiat; Nikus, Kjell; Nutile, Teresa; Ohkubo, Takayoshi; Ohnaka, Keizo; Parish, Sarah; Paternoster, Lavinia; Peng, Hao; Peters, Annette; Pham, Son T; Pinidiyapathirage, Mohitha J; Rahman, Mahfuzar; Rakugi, Hiromi; Rolandsson, Olov; Ann Rozario, Michelle; Ruggiero, Daniela; Sala, Cinzia F; Sarju, Ralhan; Shimokawa, Kazuro; Snieder, Harold; Sparsø, Thomas; Spiering, Wilko; Starr, John M; Stott, David J; Stram, Daniel O; Sugiyama, Takao; Szymczak, Silke; Tang, W H Wilson; Tong, Lin; Trompet, Stella; Turjanmaa, Väinö; Ueshima, Hirotsugu; Uitterlinden, André G; Umemura, Satoshi; Vaarasmaki, Marja; van Dam, Rob M; van Gilst, Wiek H; van Veldhuisen, Dirk J; Viikari, Jorma S; Waldenberger, Melanie; Wang, Yiqin; Wang, Aili; Wilson, Rory; Wong, Tien-Yin; Xiang, Yong-Bing; Yamaguchi, Shuhei; Ye, Xingwang; Young, Robin D; Young, Terri L; Yuan, Jian-Min; Zhou, Xueya; Asselbergs, Folkert W; Ciullo, Marina; Clarke, Robert; Deloukas, Panos; Franke, Andre; Franks, Paul W; Franks, Steve; Friedlander, Yechiel; Gross, Myron D; Guo, Zhirong; Hansen, Torben; Jarvelin, Marjo-Riitta; Jørgensen, Torben; Jukema, J Wouter; Kähönen, Mika; Kajio, Hiroshi; Kivimaki, Mika; Lee, Jong-Young; Lehtimäki, Terho; Linneberg, Allan; Miki, Tetsuro; Pedersen, Oluf; Samani, Nilesh J; Sørensen, Thorkild I A; Takayanagi, Ryoichi; Toniolo, Daniela; Ahsan, Habibul; Allayee, Hooman; Chen, Yuan-Tsong; Danesh, John; Deary, Ian J; Franco, Oscar H; Franke, Lude; Heijman, Bastiaan T; Holbrook, Joanna D; Isaacs, Aaron; Kim, Bong-Jo; Lin, Xu; Liu, Jianjun; März, Winfried; Metspalu, Andres; Mohlke, Karen L; Sanghera, Dharambir K; Shu, Xiao-Ou; van Meurs, Joyce B J; Vithana, Eranga; Wickremasinghe, Ananda R; Wijmenga, Cisca; Wolffenbuttel, Bruce H W; Yokota, Mitsuhiro; Zheng, Wei; Zhu, Dingliang; Vineis, Paolo; Kyrtopoulos, Soterios A; Kleinjans, Jos C S; McCarthy, Mark I; Soong, Richie; Gieger, Christian; Scott, James; Teo, Yik-Ying; He, Jiang; Elliott, Paul; Tai, E Shyong; van der Harst, Pim; Kooner, Jaspal S; Chambers, John C

2015-11-01

We carried out a trans-ancestry genome-wide association and replication study of blood pressure phenotypes among up to 320,251 individuals of East Asian, European and South Asian ancestry. We find genetic variants at 12 new loci to be associated with blood pressure (P = 3.9 × 10(-11) to 5.0 × 10(-21)). The sentinel blood pressure SNPs are enriched for association with DNA methylation at multiple nearby CpG sites, suggesting that, at some of the loci identified, DNA methylation may lie on the regulatory pathway linking sequence variation to blood pressure. The sentinel SNPs at the 12 new loci point to genes involved in vascular smooth muscle (IGFBP3, KCNK3, PDE3A and PRDM6) and renal (ARHGAP24, OSR1, SLC22A7 and TBX2) function. The new and known genetic variants predict increased left ventricular mass, circulating levels of NT-proBNP, and cardiovascular and all-cause mortality (P = 0.04 to 8.6 × 10(-6)). Our results provide new evidence for the role of DNA methylation in blood pressure regulation.

Pressure ulcer prevention: the role of the multidisciplinary team.

PubMed

Samuriwo, Ray

Pressure ulcer prevention has long been a priority for health professionals; however, poor pressure-ulcer-related practices like poor documentation continue to be identified. Research has shown that the attitude and behaviour of some nurses towards pressure ulcer prevention are not conducive to the best possible patient outcomes.This article reviews the findings of a Straussian grounded theory study, which sought to ascertain the value that is placed on pressure ulcer prevention by nurses, but also revealed the role that other health professionals in the multidisciplinary team play in the maintenance of skin integrity. The findings of this study which are presented in this paper highlight a number of important issues. Firstly, nurses are expected to know how to prevent and manage pressure ulcers, but in reality they are very reliant on the advice and support of other health professionals to maintain their patients' skin integrity. In addition,the level of support that nurses get from other health professionals in the multidisciplinary varies tremendously. Therefore, nurses in clinical practice need to be proactive in seeking input from other health professionals, as there are many members of the multidisciplinary team who are able to give them the advice and support that they need in prevention and management.

A Community Health Worker-Based Program for Elderly People With Hypertension in Indonesia: A Qualitative Study, 2013.

PubMed

Rahmawati, Riana; Bajorek, Beata

2015-10-15

Hypertension is prevalent in the elderly, but treatment is often inadequate, particularly in developing countries. The objective of this study was to explore the role of a community-based program in supporting patients with hypertension in an Indonesian rural community. A qualitative study comprising observation and in-depth interviews was conducted in an Integrated Health Service Post for the Elderly (IHSP-Elderly) program in Bantul district (Yogyakarta province). Eleven members of IHSP-Elderly program (ie, hypertensive patients), 3 community health workers (CHWs), and 1 district health staff member were interviewed to obtain their views about the role of the IHSP-Elderly program in hypertension management. Data were analyzed using thematic analysis. CHWs played a prominent role as the gatekeepers of health care in the rural community. In supporting hypertension management, CHWs served members of the IHSP-Elderly program by facilitating blood pressure checks and physical exercise and providing health education. Members reported various benefits, such as a healthier feeling overall, peer support, and access to affordable health care. Members felt that IHSP-Elderly program could do more to provide routine blood pressure screening and improve the process of referral to other health care services. CHWs have the potential to liaise between rural communities and the wider health care system. Their role needs to be strengthened through targeted organizational support that aims to improve delivery of, and referral to, care. Further study is needed to identify the key factors for effective CHW-based programs in rural communities and the incorporation of these programs into the health care system.

Mitochondrial division/mitophagy inhibitor (Mdivi) Ameliorates Pressure Overload Induced Heart Failure

PubMed Central

Givvimani, Srikanth; Munjal, Charu; Tyagi, Neetu; Sen, Utpal; Metreveli, Naira; Tyagi, Suresh C.

2012-01-01

Background We have previously reported the role of anti-angiogenic factors in inducing the transition from compensatory cardiac hypertrophy to heart failure and the significance of MMP-9 and TIMP-3 in promoting this process during pressure overload hemodynamic stress. Several studies reported the evidence of cardiac autophagy, involving removal of cellular organelles like mitochondria (mitophagy), peroxisomes etc., in the pathogenesis of heart failure. However, little is known regarding the therapeutic role of mitochondrial division inhibitor (Mdivi) in the pressure overload induced heart failure. We hypothesize that treatment with mitochondrial division inhibitor (Mdivi) inhibits abnormal mitophagy in a pressure overload heart and thus ameliorates heart failure condition. Materials and Methods To verify this, ascending aortic banding was done in wild type mice to create pressure overload induced heart failure and then treated with Mdivi and compared with vehicle treated controls. Results Expression of MMP-2, vascular endothelial growth factor, CD31, was increased, while expression of anti angiogenic factors like endostatin and angiostatin along with MMP-9, TIMP-3 was reduced in Mdivi treated AB 8 weeks mice compared to vehicle treated controls. Expression of mitophagy markers like LC3 and p62 was decreased in Mdivi treated mice compared to controls. Cardiac functional status assessed by echocardiography showed improvement and there is also a decrease in the deposition of fibrosis in Mdivi treated mice compared to controls. Conclusion Above results suggest that Mdivi inhibits the abnormal cardiac mitophagy response during sustained pressure overload stress and propose the novel therapeutic role of Mdivi in ameliorating heart failure. PMID:22479323

Plasma pressure distribution in the surrounding the Earth plasma ring and its role in the magnetospheric dynamics

NASA Astrophysics Data System (ADS)

Antonova, E. E.; Kirpichev, I. P.; Stepanova, M. V.

2014-08-01

We analyzed the characteristics of the plasma region surrounding the Earth at the geocentric distances between 6 and 15RE using the data of THEMIS mission from April 2007 to September 2012. The obtained averaged distributions of plasma pressure, of pressure anisotropy, and of magnetic field near the equatorial plane showed the presence of a ring-shaped structure surrounding the Earth. It was found that for quiet geomagnetic conditions the plasma pressure is nearly isotropic for all magnetic local times at geocentric distances >6RE. Taking into consideration that the minimal values of the magnetic field at the field lines near noon are shifted from the equatorial plane, we estimate the value of plasma beta parameter in the region of minimal values of the magnetic field using the Tsyganenko-2001 magnetic field model. It was found that the values of plasma beta parameter are of the order of unity for the nightside part of the ring-shaped structure in the equatorial plane and for the region of minimal values of the magnetic field in the dayside, indicating that the ring-shaped structure should play an active role in the magnetic field distortion. Comparison of obtained distribution of plasma pressure at the equatorial plane with the values of plasma pressure at low altitudes, showed that the considerable part of the auroral oval can be mapped into the analyzed plasma ring. The role of the high-beta plasma ring surrounding the Earth for Earth-Sun System disturbances is discussed.

Ultrasound-enhanced drug delivery for cancer.

PubMed

Mo, Steven; Coussios, Constantin-C; Seymour, Len; Carlisle, Robert

2012-12-01

Ultrasound, which has traditionally been used as a diagnostic tool, is increasingly being used in non-invasive therapy and drug delivery. Of particular interest to this review is the rapidly accumulating evidence that ultrasound may have a key role to play both in improving the targeting and the efficacy of drug delivery for cancer. Currently available ultrasound-triggerable vehicles are first described, with particular reference to the ultrasonic mechanism that can activate release and the suitability of the size range of the vehicle used for drug delivery. Further mechanical and thermal effects of ultrasound that can enhance extravasation and drug distribution following release are then critically reviewed. Acoustic cavitation is found to play a potentially key role both in achieving targeted drug release and enhanced extravasation at modest pressure amplitudes and acoustic energies, whilst simultaneously enabling real-time monitoring of the drug delivery process. The next challenge in ultrasound-enhanced drug delivery will thus be to develop a new generation of drug-carrying nanoparticles which are of the right size range for delivery to tumours, yet still capable of achieving initiation of cavitation activity and drug release at modest acoustic pressures and energies that have no safety implications for the patient.