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

Fundamental Understanding of Propellant/Nozzle Interaction for Rocket Nozzle Erosion Minimization Under Very High Pressure Conditions

DTIC Science & Technology

2005-08-31

conditions; with X-ray radiography for erosion rate measurements. A vortex combustor was also designed to simulate propellant product species and to...DATES COVERED Interim Progress Report, August 1, 2004 to July 31, 2005 4. TITLE AND SUBTITLE Fundamental Understanding of Propellant /Nozzle...nozzle erosion by solid- propellant combustion products. Several processes can affect the nozzle erosion rate at high pressure and temperature

Glaucoma Progression and its Relationship with Corrected and Uncorrected Intraocular Pressure in Eyes with History of Refractive Corneal Surgery.

PubMed

Kwon, Junki; Sung, Kyung Rim; Jo, Jaehyuck; Yang, Sung Ho

2018-04-20

To investigate glaucoma progression and its relationship with corrected and uncorrected intraocular pressure (IOP) in patients with a history of refractive corneal surgery (RCS). Totally, 56 eyes of 56 primary open-angle glaucoma patients who had a history of RCS were included. Mean keratometry and central corneal thickness were measured at the time of glaucoma diagnosis. Three IOP measurements, i.e., uncorrected IOP ( UC IOP) and corrected IOP calculated by applying the Kohlhaas ( CK IOP) and Ehlers ( CE IOP) formulas, were used. Participants were categorized into two groups (low-teen [<15 mmHg] and high-teen [≥15 mmHg] groups) according to the mean follow-up IOP, in each of the three IOP measurements. Glaucoma progression was determined based on either structurally or functionally by stereoscopic optic disc/retinal nerve fiber layer photographs or visual field tests. Kaplan-Meier survival curves were compared between the low-teens group and high-teens group for each IOP measurement. Risk factors for glaucoma progression, including uncorrected and corrected IOP measurements, were analyzed using a Cox proportional-hazards model. Among total eyes, glaucoma progression was found in 19 (34%) eyes during 4.3 years of mean follow-up period. Individual values of uncorrected IOP and corrected IOP showed significant differences (p < 0.001). Incidence of glaucoma progression was higher in high-teens group than in low-teens group by corrected IOP values (both Kohlhaas and Ehlers, p = 0.006, 0.003), but not by uncorrected IOP values (p = 0.749). The cumulative probability of glaucoma progression was significantly greater in the high-teens group than in the low-teens group using the Elhers formula determined by Kaplan-Meier analysis (p = 0.030). For glaucoma eyes with history of RCS, high-teen group by corrected mean follow-up IOP showed more glaucoma progression than low-teen group. More intensive IOP-lowering treatment will be required for patient with high-teen follow-up corrected IOP to prevent glaucoma progression.

Psychosocial Factors Are Associated With Blood Pressure Progression Among African Americans in the Jackson Heart Study

PubMed Central

Sims, Mario; Higginbotham, John C.; Crowther, Martha R.; Wyatt, Sharon B.; Musani, Solomon K.; Payne, Thomas J.; Fox, Ervin R.; Parton, Jason M.

2016-01-01

BACKGROUND Research that examines the associations of psychosocial factors with incident hypertension among African Americans (AA) is limited. Using Jackson Heart Study (JHS) data, we examined associations of negative affect and stress with incident hypertension and blood pressure (BP) progression among AA. METHODS Our sample consisted of 1,656 normotensive participants at baseline (2000–2004) (mean age 47±12; 61% women). We investigated associations of negative affect (cynical distrust, anger-in, anger-out, and depressive symptoms) and stress (perceived stress, weekly stress inventory (WSI)-event, WSI-impact, and major life events) with BP progression (an increase by one BP stage as defined by JNC VII) and incident hypertension by examination 2 (2005–2008). Poisson regression analysis was utilized to examine the prevalence ratios (PRs; 95% confidence interval (CI)) of BP tracking and incident hypertension with psychosocial factors, adjusting for baseline age, sex, socioeconomic status (SES), and hypertension risk factors. RESULTS Fifty-six percentage of the sample (922 cases) had BP progression from 2005 to 2008. After adjustment for age, sex, and SES, a high anger-out score was associated with a 20% increased risk of BP progression compared to a low anger-out score (PR 1.20; 95% CI 1.05–1.36). High depressive symptoms score was associated with BP progression in the age, sex, and SES-adjusted model (PR 1.14; 95% CI 1.00–1.30). High WSI-event scores were associated with BP progression in the fully adjusted model (PR 1.21; 95% CI 1.04–1.40). We did not observe significant associations with any of the psychosocial measures and incident hypertension. CONCLUSIONS Psychosocial factors were associated with BP progression, with the strongest evidence for number of stressful events that occurred. PMID:26964661

Intensive Blood-Pressure Control in Hypertensive Chronic Kidney Disease

PubMed Central

Appel, Lawrence J.; Wright, Jackson T.; Greene, Tom; Agodoa, Lawrence Y.; Astor, Brad C.; Bakris, George L.; Cleveland, William H.; Charleston, Jeanne; Contreras, Gabriel; Faulkner, Marquetta L.; Gabbai, Francis B.; Gassman, Jennifer J.; Hebert, Lee A.; Jamerson, Kenneth A.; Kopple, Joel D.; Kusek, John W.; Lash, James P.; Lea, Janice P.; Lewis, Julia B.; Lipkowitz, Michael S.; Massry, Shaul G.; Miller, Edgar R.; Norris, Keith; Phillips, Robert A.; Pogue, Velvie A.; Randall, Otelio S.; Rostand, Stephen G.; Smogorzewski, Miroslaw J.; Toto, Robert D.; Wang, Xuelei

2013-01-01

BACKGROUND In observational studies, the relationship between blood pressure and end-stage renal disease (ESRD) is direct and progressive. The burden of hypertension-related chronic kidney disease and ESRD is especially high among black patients. Yet few trials have tested whether intensive blood-pressure control retards the progression of chronic kidney disease among black patients. METHODS We randomly assigned 1094 black patients with hypertensive chronic kidney disease to receive either intensive or standard blood-pressure control. After completing the trial phase, patients were invited to enroll in a cohort phase in which the blood-pressure target was less than 130/80 mm Hg. The primary clinical outcome in the cohort phase was the progression of chronic kidney disease, which was defined as a doubling of the serum creatinine level, a diagnosis of ESRD, or death. Follow-up ranged from 8.8 to 12.2 years. RESULTS During the trial phase, the mean blood pressure was 130/78 mm Hg in the intensive-control group and 141/86 mm Hg in the standard-control group. During the cohort phase, corresponding mean blood pressures were 131/78 mm Hg and 134/78 mm Hg. In both phases, there was no significant between-group difference in the risk of the primary outcome (hazard ratio in the intensive-control group, 0.91; P = 0.27). However, the effects differed according to the baseline level of proteinuria (P = 0.02 for interaction), with a potential benefit in patients with a protein-to-creatinine ratio of more than 0.22 (hazard ratio, 0.73; P = 0.01). CONCLUSIONS In overall analyses, intensive blood-pressure control had no effect on kidney disease progression. However, there may be differential effects of intensive blood-pressure control in patients with and those without baseline proteinuria. (Funded by the National Institute of Diabetes and Digestive and Kidney Diseases, the National Center on Minority Health and Health Disparities, and others.) PMID:20818902

Management of Hypertension in Diabetic Nephropathy: How Low Should We Go?

PubMed

Sternlicht, Hillel; Bakris, George L

2016-01-01

Hypertension is a frequent comorbidity often following the development of diabetic nephropathy among individuals with type 1 diabetes and affecting most patients with type 2 diabetes at the time of diagnosis. Multiple prospective randomized placebo-controlled trials demonstrate that tight blood pressure control among patients with diabetic nephropathy reduces the rates of macrovascular and microvascular complications. While randomized trials exist and support a blood pressure goal of <140/90 mm Hg for patients with nondiabetic kidney disease, there are no prospective data regarding a specific blood pressure goal on progression of diabetic nephropathy. Retrospective data analyses from trials show a linear relationship between either baseline or achieved study blood pressure and progression of nephropathy. Very high albuminuria is a hallmark of diabetic nephropathy with reductions by either angiotensin converting enzyme inhibitors (ACEi) or angiotensin receptor blocker (ARB) monotherapy associated with slowed nephropathy progression. However, combination antihypertensive therapy, while decreasing proteinuria, augments the risk of hyperkalemia, hypotension, and kidney dysfunction. Given the lack of trial data for a BP goal among patients with diabetic nephropathy, prospective trials are needed to define the optimal blood pressure necessary to preserve kidney function. At present, guideline blood pressure goals of less than 140/90 mm Hg and the use of ACEi or ARB therapy for those with more than 300 mg of albuminuria are mandated. © 2016 S. Karger AG, Basel.

Effects of increasing left ventricular filling pressure in patients with acute myocardial infarction

PubMed Central

Russell, Richard O.; Rackley, Charles E.; Pombo, Jaoquin; Hunt, David; Potanin, Constantine; Dodge, Harold T.

1970-01-01

Left ventricular performance in 19 patients with acute myocardial infarction has been evaluated by measuring left ventricular response in terms of cardiac output, stroke volume, work, and power to progressive elevation of filling pressure accomplished by progressive expansion of blood volume with rapid infusion of low molecular weight dextran. Such infusion can elevate the cardiac output, stroke volume, work, and power and thus delineate the function of the left ventricle by Frank-Starling function curves. Left ventricular filling pressure in the range of 20-24 mm Hg was associated with the peak of the curves and when the filling pressure exceeded this range, the curves became flattened or decreased. An increase in cardiac output could be maintained for 4 or more hr. Patients with a flattened function curve had a high mortality in the ensuing 8 wk. The function curve showed improvement in myocardial function during the early convalescence. When left ventricular filling pressure is monitored directly or as pulmonary artery end-diastolic pressure, low molecular weight dextran provides a method for assessment of left ventricular function. Images PMID:5431663

Recent progress in high pressure metrology in Europe

NASA Astrophysics Data System (ADS)

Sabuga, Wladimir; Pražák, Dominik; Rabault, Thierry

2014-08-01

Five European national metrology institutes in collaboration with a university, a research institute and five industrial companies are working on a joint research project within a framework of the European Metrology Research Programme aimed at development of 1.6 GPa primary and 1.5 GPa transfer pressure standards. Two primary pressure standards were realised as pressure-measuring multipliers, each consisting of a low pressure and a high pressure (HP) piston-cylinder assembly (PCA). A special design of the HP PCAs was developed in which a tungsten carbide cylinder is supported by two thermally shrunk steel sleeves and, additionally, by jacket pressure applied to the outside of the outer sleeve. Stress-strain finite element analysis (FEA) was performed to predict behaviour of the multipliers and a pressure generation system. With FEA, the pressure distortion coefficient was determined, taking into account irregularities of the piston-cylinder gap. Transfer pressure standards up to 1.5 GPa are developed on the basis of modern 1.5 GPa pressure transducers. This project shall solve a discrepancy between the growing needs of the industry demanding precise traceable calibrations of the high pressure transducers and the absence of adequate primary standards for pressures higher than 1 GPa in the European Union today.

Telmisartan on top of antihypertensive treatment does not prevent progression of cerebral white matter lesions in the prevention regimen for effectively avoiding second strokes (PRoFESS) MRI substudy.

PubMed

Weber, Ralph; Weimar, Christian; Blatchford, Jon; Hermansson, Karin; Wanke, Isabel; Möller-Hartmann, Claudia; Gizewski, Elke R; Forsting, Michael; Demchuk, Andrew M; Sacco, Ralph L; Saver, Jeffrey L; Warach, Steven; Diener, Hans-Christoph; Diehl, Anke

2012-09-01

High blood pressure is one of the main risk factors for cerebral white matter lesions (WMLs). There is limited evidence from one randomized trial that blood pressure-lowering is able to slow WML progression. We investigated whether telmisartan prevents WML progression in the imaging substudy of the Prevention Regimen for Effectively Avoiding Second Strokes (PRoFESS) trial. This predefined substudy comprised 771 patients (mean age, 65 years) with recent ischemic stroke of noncardioembolic origin who received telmisartan or placebo during a mean follow-up of 27.9 (SD, 7.6) months and had 2 evaluable MRI examinations after index stroke and at study closeout. All MRI scans were centrally adjudicated for progression of periventricular and subcortical WML by 2 neuroradiologists blinded to treatment allocation. Mean blood pressure was 3.0/1.3 mm Hg lower with telmisartan compared with placebo at follow-up MRI. There was no statistically significant difference in progression of the mean periventricular WML score (least squares mean difference, 0.14; 95% CI, -0.12 to 0.39; P=0.29) and mean subcortical WML diameter (least squares mean difference, -0.35 mm; 95% CI, -1.00 to 0.31 mm; P=0.30) during follow-up between patients on telmisartan and placebo. Treatment with telmisartan on top of existing antihypertensive medication did not result in significant blood pressure-lowering and did not prevent the progression of WML in patients with a recent ischemic stroke in this patient cohort. Our analysis is limited by the relatively short follow-up period. Clinical Trial Registration- URL: http://clinicaltrials.gov. Unique Identifier: NCT00153062.

Chemistry Division: Annual progress report for period ending March 31, 1987

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

Not Available

1987-08-01

This report is divided into the following sections: coal chemistry; aqueous chemistry at high temperatures and pressures; geochemistry of crustal processes to high temperatures and pressures; chemistry of advanced inorganic materials; structure and dynamics of advanced polymeric materials; chemistry of transuranium elements and compounds; separations chemistry; reactions and catalysis in molten salts; surface science related to heterogeneous catalysis; electron spectroscopy; chemistry related to nuclear waste disposal; computational modeling of security document printing; and special topics. (DLC)

Progress in modeling hypersonic turbulent boundary layers

NASA Technical Reports Server (NTRS)

Zeman, Otto

1993-01-01

A good knowledge of the turbulence structure, wall heat transfer, and friction in turbulent boundary layers (TBL) at high speeds is required for the design of hypersonic air breathing airplanes and reentry space vehicles. This work reports on recent progress in the modeling of high speed TBL flows. The specific research goal described here is the development of a second order closure model for zero pressure gradient TBL's for the range of Mach numbers up to hypersonic speeds with arbitrary wall cooling requirements.

Effects of positive end-expiratory pressure on brain tissue oxygen pressure of severe traumatic brain injury patients with acute respiratory distress syndrome: A pilot study.

PubMed

Nemer, Sérgio Nogueira; Caldeira, Jefferson B; Santos, Ricardo G; Guimarães, Bruno L; Garcia, João Márcio; Prado, Darwin; Silva, Ricardo T; Azeredo, Leandro M; Faria, Eduardo R; Souza, Paulo Cesar P

2015-12-01

To verify whether high positive end-expiratory pressure levels can increase brain tissue oxygen pressure, and also their effects on pulse oxygen saturation, intracranial pressure, and cerebral perfusion pressure. Twenty traumatic brain injury patients with acute respiratory distress syndrome were submitted to positive end-expiratory pressure levels of 5, 10, and 15 cm H2O progressively. The 3 positive end-expiratory pressure levels were used during 20 minutes for each one, whereas brain tissue oxygen pressure, oxygen saturation, intracranial pressure, and cerebral perfusion pressure were recorded. Brain tissue oxygen pressure and oxygen saturation increased significantly with increasing positive end-expiratory pressure from 5 to 10 and from 10 to 15 cm H2O (P=.0001 and P=.0001 respectively). Intracranial pressure and cerebral perfusion pressure did not differ significantly with increasing positive end-expiratory pressure from 5 to 10 and from 10 to 15 cm H2O (P=.16 and P=.79 respectively). High positive end-expiratory pressure levels increased brain tissue oxygen pressure and oxygen saturation, without increase in intracranial pressure or decrease in cerebral perfusion pressure. High positive end-expiratory pressure levels can be used in severe traumatic brain injury patients with acute respiratory distress syndrome as a safe alternative to improve brain oxygenation. Copyright © 2015 Elsevier Inc. All rights reserved.

SIGHT - A balloon borne hard X-ray telescope

NASA Technical Reports Server (NTRS)

Wilkerson, J.; Edberg, T. K.; Hurley, K.; Lin, R. P.; Parsons, A.

1991-01-01

The authors report on progress toward developing a large-area, high-pressure xenon gas scintillator for use in hard X-ray astrophysics. Proof test results for a low-mass pressure vessel are presented. The design of a high-voltage multiplier board operating inside the scintillation chamber is discussed. The development of tetrakis-dimethylamine-thylene (TMAE)-based proportional tubes for detecting primary scintillation in the xenon is described. Finally, Monte Carlo tests of a scheme to use conventional photomultiplier tubes are discussed.

Collisional and radiative processes in high-pressure discharge plasmas

NASA Astrophysics Data System (ADS)

Becker, Kurt H.; Kurunczi, Peter F.; Schoenbach, Karl H.

2002-05-01

Discharge plasmas at high pressures (up to and exceeding atmospheric pressure), where single collision conditions no longer prevail, provide a fertile environment for the experimental study of collisions and radiative processes dominated by (i) step-wise processes, i.e., the excitation of an already excited atomic/molecular state and by (ii) three-body collisions leading, for instance, to the formation of excimers. The dominance of collisional and radiative processes beyond binary collisions involving ground-state atoms and molecules in such environments allows for many interesting applications of high-pressure plasmas such as high power lasers, opening switches, novel plasma processing applications and sputtering, absorbers and reflectors for electromagnetic waves, remediation of pollutants and waste streams, and excimer lamps and other noncoherent vacuum-ultraviolet light sources. Here recent progress is summarized in the use of hollow cathode discharge devices with hole dimensions in the range 0.1-0.5 mm for the generation of vacuum-ultraviolet light.

Diffuse interfacelets in transcritical flows of propellants into high-pressure combustors

NASA Astrophysics Data System (ADS)

Urzay, Javier; Jofre, Lluis

2017-11-01

Rocket engines and new generations of high-power jet engines and diesel engines oftentimes involve the injection of one or more reactants at subcritical temperatures into combustor environments at high pressures, and more particularly, at pressures higher than those corresponding to the critical points of the individual components of the mixture, which typically range from 13 to 50 bars for most propellants. This class of trajectories in the thermodynamic space has been traditionally referred to as transcritical. Under particular conditions often found in hydrocarbon-fueled chemical propulsion systems, and despite the prevailing high pressures, the flow in the combustor may contain regions close to the injector where a diffuse interface is formed in between the fuel and oxidizer streams that is sustained by surface-tension forces as a result of the elevation of the critical pressure of the mixture. This talk describes progress towards modeling these effects in the conservation equations. Funded by the US Department of Energy.

Physiologic Mechanisms Underlying the Failure of the Shock Index as a Tool for Accurate Assessment of Patient Status during Progressive Simulated Hemorrhage

DTIC Science & Technology

2013-08-01

in central blood volume similar to hemorrhage in humans. Lower-body negative- pressure (LBNP) is a unique physiologic model that has been adopted to...relatively high tolerance (HT) to reduced blood volume, while 30% to 35% display low toler- ance (LT), with earlier onset of cardiovascular instability (i.e... pressure were recorded by infrared finger photoplethysmography (Finometer Blood Pressure Mon- itor, TNO-TPD Biomedical Instrumentation, Amsterdam

Progress on the Development of Low Pressure High Density Plasmas on the Helicon Plasma Experiment (HPX)

NASA Astrophysics Data System (ADS)

James, R. W.; Chamberlin, A.; Azzari, P.; Crilly, P.; Emami, T.; Hopson, J.; Karama, J.; Green, A.; Paolino, R. N.; Sandri, E.; Turk, J.; Wicke, M.; Cgapl Team

2017-10-01

The small Helicon Plasma Experiment (HPX) at the Coast Guard Academy Plasma Lab (CGAPL), continues to progress toward utilizing the reputed high densities (1013 cm-3 and higher) at low pressure (.01 T) [1] of helicons, for eventual high temperature and density diagnostic development in future laboratory investigations. HPX is designed to create repeatedly stable plasmas ( 20-30 ns) induced by an RF frequency in the 10 to 70 MHz range. HPX has constructed a protected Langmuir probe where raw data will be collected, compared to the RF compensated probe and used to measure the plasma's density, temperature, and behavior during experiments. Our 2.5 J YAG laser Thomson Scattering system backed by a 32-channel Data Acquisition (DAQ) system is capable 12 bits of sampling precision at 2 MS/s for HPX plasma property investigations are being integrated into the existing diagnostics and control architecture. Progress on the construction of the RF coupling system, Helicon Mode development, and magnetic coils, along with observations from the Thomson Scattering, particle, and electromagnetic scattering diagnostics will be reported. Supported by U.S. DEPS Grant [HEL-JTO] PRWJFY17.

Case Study: Application of Isometric Progressive Resistance Oropharyngeal Therapy Using the Madison Oral Strengthening Therapeutic Device

PubMed Central

Juan, Junerose; Hind, Jacqueline; Jones, Corinne; McCulloch, Timothy; Gangnon, Ron; Robbins, JoAnne

2013-01-01

Purpose Isometric progressive resistance oropharyngeal (I-PRO) therapy improves swallowing function; however, current devices utilize a single sensor that provides limited information or are prohibitively expensive. This single-subject study presents results of I-PRO therapy, detraining, and maintenance using the 5-sensor Madison Oral Strengthening Therapeutic (MOST) device combined with upper esophageal sphincter (UES) dilatation. Methods A 56-year-old female nurse who was 27 months post stroke and subsequent to traditional behavioral interventions and UES dilatations presented limited to gastrostomy tube intake only and expectorating all saliva. She completed 8 weeks of I-PRO therapy, 5 weeks of detraining, and 9 weeks of I-PRO maintenance (reduced frequency) followed by a third UES dilatation post intervention. Data included diet inventory, lingual pressures (MOST), lingual volume (magnetic resonance imaging), postswallow residue (videofl uoroscopy), UES and pharyngeal pressures (high-resolution manometry), and quality of life (QOL). Results Findings after 8 weeks of I-PRO therapy were progression to general oral diet, 15 lb weight gain, increased isometric pressures (Δ >16 kPa) with transference to swallowing pressures, increased lingual volume (8.3%), reduced pharyngeal wall residue (P = .03), increased pharyngeal pressures (Δ > 43 mm Hg) and increased UES opening (nadir) pressures (Δ > 9 mm Hg) with improved temporopressure coordination across the pharynx, and improved QOL. After detraining, decreased isometric pressures and reduced UES opening were noted. After I-PRO maintenance, isometric anterior lingual pressures returned to levels noted after the 8 weeks of intervention. Conclusion I-PRO therapy, facilitated by the MOST device combined with instrumental UES dilatation, improved swallow safety, increased oropharyngeal intake, and facilitated UES opening while enriching QOL. PMID:24091287

Numerical simulation on the powder propellant pickup characteristics of feeding system at high pressure

NASA Astrophysics Data System (ADS)

Sun, Haijun; Hu, Chunbo; Zhu, Xiaofei

2017-10-01

A numerical study of powder propellant pickup progress at high pressure was presented in this paper by using two-fluid model with kinetic theory of granular flow in the computational fluid dynamics software package ANSYS/Fluent. Simulations were conducted to evaluate the effects of initial pressure, initial powder packing rate and mean particle diameter on the flow characteristics in terms of velocity vector distribution, granular temperature, pressure drop, particle velocity and volume. The numerical results of pressure drop were also compared with experiments to verify the TFM model. The simulated results show that the pressure drop value increases as the initial pressure increases, and the granular temperature under the conditions of different initial pressures and packing rates is almost the same in the area of throttling orifice plate. While there is an appropriate value for particle size and packing rate to form a ;core-annulus; structure in powder box, and the time-averaged velocity vector distribution of solid phase is inordinate.

Psychosocial Factors Are Associated With Blood Pressure Progression Among African Americans in the Jackson Heart Study.

PubMed

Ford, Cassandra D; Sims, Mario; Higginbotham, John C; Crowther, Martha R; Wyatt, Sharon B; Musani, Solomon K; Payne, Thomas J; Fox, Ervin R; Parton, Jason M

2016-08-01

Research that examines the associations of psychosocial factors with incident hypertension among African Americans (AA) is limited. Using Jackson Heart Study (JHS) data, we examined associations of negative affect and stress with incident hypertension and blood pressure (BP) progression among AA. Our sample consisted of 1,656 normotensive participants at baseline (2000-2004) (mean age 47±12; 61% women). We investigated associations of negative affect (cynical distrust, anger-in, anger-out, and depressive symptoms) and stress (perceived stress, weekly stress inventory (WSI)-event, WSI-impact, and major life events) with BP progression (an increase by one BP stage as defined by JNC VII) and incident hypertension by examination 2 (2005-2008). Poisson regression analysis was utilized to examine the prevalence ratios (PRs; 95% confidence interval (CI)) of BP tracking and incident hypertension with psychosocial factors, adjusting for baseline age, sex, socioeconomic status (SES), and hypertension risk factors. Fifty-six percentage of the sample (922 cases) had BP progression from 2005 to 2008. After adjustment for age, sex, and SES, a high anger-out score was associated with a 20% increased risk of BP progression compared to a low anger-out score (PR 1.20; 95% CI 1.05-1.36). High depressive symptoms score was associated with BP progression in the age, sex, and SES-adjusted model (PR 1.14; 95% CI 1.00-1.30). High WSI-event scores were associated with BP progression in the fully adjusted model (PR 1.21; 95% CI 1.04-1.40). We did not observe significant associations with any of the psychosocial measures and incident hypertension. Psychosocial factors were associated with BP progression, with the strongest evidence for number of stressful events that occurred. © American Journal of Hypertension, Ltd 2016. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Effect of different body postures on the pressures generated during an L-1 maneuver.

PubMed

Williams, C A; Lind, A R; Wiley, R L; Douglas, J E; Miller, G

1988-10-01

Changes in blood pressure, intrathoracic pressure, heart rate and the electromyographic activity of various muscle groups were determined while nine male subjects performed 15-s L-1 straining maneuvers at four spine-to-thigh angles (70, 84, 94, and 105 degrees) and two seatback angles (30 and 60 degrees). There was no significant difference between the changes in these variables due to the different body positions. At the onset of the L-1, arterial pressure immediately increased to 195 +/- 5 mm Hg, but fell progressively during the next 5 s to 160 +/- 5 mm Hg. It remained constant during the next 5 s of the maneuver and then recovered to 180 +/- mm Hg during the last 5 s of the maneuver. Esophageal pressure followed essentially the same pattern of response, but heart rate progressively increased during the entire L-1. No one muscle group was utilized more than another. Inflation of an anti-G suit to 4 PSI had no effect on the variables measured. Generation of high arterial pressures during L-1 maneuvers is transitory and not affected either positively or negatively by altering subject body position.

Pressure-induced dramatic changes in organic–inorganic halide perovskites

PubMed Central

Yang, Wenge

2017-01-01

Organic–inorganic halide perovskites have emerged as a promising family of functional materials for advanced photovoltaic and optoelectronic applications with high performances and low costs. Various chemical methods and processing approaches have been employed to modify the compositions, structures, morphologies, and electronic properties of hybrid perovskites. However, challenges still remain in terms of their stability, the use of environmentally unfriendly chemicals, and the lack of an insightful understanding into structure–property relationships. Alternatively, pressure, a fundamental thermodynamic parameter that can significantly alter the atomic and electronic structures of functional materials, has been widely utilized to further our understanding of structure–property relationships, and also to enable emergent or enhanced properties of given materials. In this perspective, we describe the recent progress of high-pressure research on hybrid perovskites, particularly regarding pressure-induced novel phenomena and pressure-enhanced properties. We discuss the effect of pressure on structures and properties, their relationships and the underlying mechanisms. Finally, we give an outlook on future research avenues in which high pressure and related alternative methods such as chemical tailoring and interfacial engineering may lead to novel hybrid perovskites uniquely suited for high-performance energy applications. PMID:29147500

High-Pressure Turbulent Flame Speeds and Chemical Kinetics of Syngas Blends with and without Impurities

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

Peterson, Eric; Mathieu, Olivier; Morones, Anibal

2014-12-01

This Topical Report documents the first year of the project, from October 1, 2013 through September 30, 2014. Efforts for this project included experiments to characterize the atmospheric-pressure turbulent flame speed vessel over a range of operating conditions (fan speeds and turbulent length scales). To this end, a new LDV system was acquired and set up for the detailed characterization of the turbulence field. Much progress was made in the area of impurity kinetics, which included a numerical study of the effect of impurities such as NO2, NO, H2S, and NH3 on ignition delay times and laminar flame speeds ofmore » syngas blends at engine conditions. Experiments included a series of laminar flame speed measurements for syngas (CO/H2) blends with various levels of CH4 and C2H6 addition, and the results were compared to the chemical kinetics model of NUI Galway. Also, a final NOx kinetics mechanism including ammonia was assembled, and a journal paper was written and is now in press. Overall, three journal papers and six conference papers related to this project were published this year. Finally, much progress was made on the design of the new high-pressure turbulent flame speed facility. An overall design that includes a venting system was decided upon, and the detailed design is in progress.« less

Effect of hydrogen pressure on free radicals in direct coal liquefaction/coprocessing

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

Seehra, M.S.; Ibrahim, M.M.

1995-12-31

The objective of this study was to investigate the coprocessing of coal with waste tires and commingled plastics and to characterize the relevant catalysts, using high pressure/high temperature in-situ ESR (Electron Spin Resonance) spectroscopy. The recent results from high pressure ESR spectroscopy are emphasized. During this period, considerable progress was made in developing the high pressure capabilities in in-situ ESR spectroscopy and new results carried out in 1000 psi of H{sub 2}gas are presented. In these experiments, sapphire tubes were used to contain the high pressures at temperatures up to 500{degrees}C. Results of the experiments carried out under 1000 psimore » of H{sub 2} are compared with those under 1000 psi of non-interacting argon and with the earlier experiments in flowing H{sub 2} gas where the volatiles are removed by the flowing gas. In these experiments, the free radical density N of the Blind Canyon coal was measured at each temperature and pressure by double integration of the ESR signal and calibrating it against a standard. The details of the experimental apparatus and procedures have been described in earlier publications.« less

Condensed matter physics of planets - Puzzles, progress and predictions

NASA Technical Reports Server (NTRS)

Stevenson, D. J.

1984-01-01

Attention is given to some of the major unresolved issues concerned with the physics of planetary interiors. The important advances in observations, and experimental and theoretical investigations are briefly reviewed, and some areas for further study are identified, including: the characteristics of atomic and electronic degrees of freedom at the high pressures and temperatures typical of a condensed planetary core; the behavior of water at megabar pressures; and the nature of the core-alloy in the earth and in the core mantle phase boundary. Consideration is also given to the behavior of carbon at high pressures and temperatures in the presence of oxygen and hydrogen; the behavior of the volatile ice assemblage in Titan at pressures of 2-40 kbar; and the electrical conductivities of matter under planetary core conditions.

High pressure jet flame numerical analysis of CO emissions by means of the flamelet generated manifolds technique

NASA Astrophysics Data System (ADS)

Donini, A.; Martin, S. M.; Bastiaans, R. J. M.; van Oijen, J. A.; de Goey, L. P. H.

2013-10-01

In the present paper a computational analysis of a high pressure confined premixed turbulent methane/air jet flames is presented. In this scope, chemistry is reduced by the use of the Flamelet Generated Manifold method [1] and the fluid flow is modeled in an LES and RANS context. The reaction evolution is described by the reaction progress variable, the heat loss is described by the enthalpy and the turbulence effect on the reaction is represented by the progress variable variance. The interaction between chemistry and turbulence is considered through a presumed probability density function (PDF) approach. The use of FGM as a combustion model shows that combustion features at gas turbine conditions can be satisfactorily reproduced with a reasonable computational effort. Furthermore, the present analysis indicates that the physical and chemical processes controlling carbon monoxide (CO) emissions can be captured only by means of unsteady simulations.

Horizontal Two Phase Flow Regime Identification: Comparison of Pressure Signature, Electrical Capacitance Tomography (ECT) and High Speed Visualization (Postprint)

DTIC Science & Technology

2012-11-01

W., and Mudawar , I., "Measurement and Correlation of Critical Heat Flux in Two-Phase Micro-Channel Heat Sinks," International Journal of Heat and...Mass Transfer, Vol. 47, No. 10-11, 2004, pp. 2045-2059. 3 Zhang, H., Mudawar , I., and Hasan, M. M., "Photographic Study of High-Flux Subcooled Flow...component Fow in Pipes," Chemical Engineering Progress, Vol. 45, 1949, pp. 39-48. 34 Qu, W., and Mudawar , I., "Measurement and Prediction of Pressure

High temperature NASP engine seals: A technology review

NASA Technical Reports Server (NTRS)

Steinetz, Bruce M.; Dellacorte, Christopher; Tong, Mike

1991-01-01

Progress in developing advanced high temperature engine seal concepts and related sealing technologies for advanced hypersonic engines are reviewed. Design attributes and issues requiring further development for both the ceramic wafer seal and the braided ceramic rope seal are examined. Leakage data are presented for these seals for engine simulated pressure and temperature conditions and compared to a target leakage limit. Basic elements of leakage flow models to predict leakage rates for each of these seals over the wide range of pressure and temperature conditions anticipated in the engine are also presented.

High-temperature unimolecular decomposition of ethyl propionate

NASA Astrophysics Data System (ADS)

Giri, Binod Raj; AlAbbad, Mohammed; Farooq, Aamir

2016-11-01

This work reports rate coefficients of the thermal unimolecular decomposition reaction of ethyl propionate (EP) behind reflected shock waves over the temperature range of 976-1300 K and pressures of 825-1875 Torr. The reaction progress was monitored by detecting C2H4 near 10.532 μm using CO2 gas laser absorption. In addition, G3//MP2/aug-cc-pVDZ and master equation calculations were performed to assess the pressure- and temperature-dependence of the reaction. Our calculations revealed that C2H4 elimination occurs via a six-centered retro-ene transition state. Our measured rate data are close to the high-pressure limit and showed no discernable temperature fall off.

Phonon triggered rhombohedral lattice distortion in vanadium at high pressure

DOE PAGES

Antonangeli, Daniele; Farber, Daniel L.; Bosak, Alexei; ...

2016-08-19

In spite of the simple body-centered-cubic crystal structure, the elements of group V, vanadium, niobium and tantalum, show strong interactions between the electronic properties and lattice dynamics. Further, these interactions can be tuned by external parameters, such as pressure and temperature. We used inelastic x-ray scattering to probe the phonon dispersion of single-crystalline vanadium as a function of pressure to 45 GPa. Our measurements show an anomalous high-pressure behavior of the transverse acoustic mode along the (100) direction and a softening of the elastic modulus C44 that triggers a rhombohedral lattice distortion occurring between 34 and 39 GPa. Lastly, ourmore » results provide the missing experimental confirmation of the theoretically predicted shear instability arising from the progressive intra-band nesting of the Fermi surface with increasing pressure, a scenario common to all transition metals of group V.« less

Effects of oral contraceptives on sympathetic nerve activity during orthostatic stress in young, healthy women

PubMed Central

Klein, Jenna C.; Schwartz, Christopher E.

2010-01-01

Recent studies report that the menstrual cycle alters sympathetic neural responses to orthostatic stress in young, eumenorrheic women. The purpose of the present study was to determine whether oral contraceptives (OC) influence sympathetic neural activation during an orthostatic challenge. Based on evidence that sympathetic baroreflex sensitivity (BRS) is increased during the “low hormone” (LH) phase (i.e., placebo pills) in women taking OC, we hypothesized an augmented muscle sympathetic nerve activity (MSNA) response to orthostatic stress during the LH phase. MSNA, mean arterial pressure (MAP), and heart rate (HR) were recorded during progressive lower body negative pressure (LBNP; −5, −10, −15, −20, −30, −40 mmHg; 3 min/stage) in 12 healthy women taking OC (age 22 ± 1 years). Sympathetic BRS was assessed by examining relations between spontaneous fluctuations of diastolic arterial pressure and MSNA. Subjects were examined twice: once during LH phase and once ∼3 wk after LH during the “high hormone” phase (randomized order). Resting MSNA (10 ± 2 vs. 13 ± 2 bursts/min), MAP (85 ± 3 vs. 84 ± 3 mmHg), and HR (62 ± 2 vs. 65 ± 3 beats/min) were not different between phases. MSNA and HR increased during progressive LBNP (P < 0.001), and these increases were similar between phases. Progressive LBNP did not change MAP during either phase. Sympathetic BRS increased during progressive LBNP, but these responses were not different between LH and high hormone phases. In conclusion, our results demonstrate that OCs do not alter cardiovascular and sympathetic neural responses to an orthostatic challenge in young, healthy women. PMID:19828840

Evaluation of a Progressive Mobility Protocol in Postoperative Cardiothoracic Surgical Patients.

PubMed

Floyd, Shawn; Craig, Sarah W; Topley, Darla; Tullmann, Dorothy

2016-01-01

Cardiothoracic surgical patients are at high risk for complications related to immobility, such as increased intensive care and hospital length of stay, intensive care unit readmission, pressure ulcer development, and deep vein thrombosis/pulmonary embolus. A progressive mobility protocol was started in the thoracic cardiovascular intensive care unit in a rural academic medical center. The purpose of the progressive mobility protocol was to increase mobilization of postoperative patients and decrease complications related to immobility in this unique patient population. A matched-pairs design was used to compare a randomly selected sample of the preintervention group (n = 30) to a matched postintervention group (n = 30). The analysis compared outcomes including intensive care unit and hospital length of stay, intensive care unit readmission occurrence, pressure ulcer prevalence, and deep vein thrombosis/pulmonary embolism prevalence between the 2 groups. Although this comparison does not achieve statistical significance (P < .05) for any of the outcomes measured, it does show clinical significance in a reduction in hospital length of stay, intensive care unit days, in intensive care unit readmission rate, and a decline in pressure ulcer prevalence, which is the overall goal of progressive mobility. This study has implications for nursing, hospital administration, and therapy services with regard to staffing and cost savings related to fewer complications of immobility. Future studies with a larger sample size and other populations are warranted.

Computational Modeling of 3D Tumor Growth and Angiogenesis for Chemotherapy Evaluation

PubMed Central

Tang, Lei; van de Ven, Anne L.; Guo, Dongmin; Andasari, Vivi; Cristini, Vittorio; Li, King C.; Zhou, Xiaobo

2014-01-01

Solid tumors develop abnormally at spatial and temporal scales, giving rise to biophysical barriers that impact anti-tumor chemotherapy. This may increase the expenditure and time for conventional drug pharmacokinetic and pharmacodynamic studies. In order to facilitate drug discovery, we propose a mathematical model that couples three-dimensional tumor growth and angiogenesis to simulate tumor progression for chemotherapy evaluation. This application-oriented model incorporates complex dynamical processes including cell- and vascular-mediated interstitial pressure, mass transport, angiogenesis, cell proliferation, and vessel maturation to model tumor progression through multiple stages including tumor initiation, avascular growth, and transition from avascular to vascular growth. Compared to pure mechanistic models, the proposed empirical methods are not only easy to conduct but can provide realistic predictions and calculations. A series of computational simulations were conducted to demonstrate the advantages of the proposed comprehensive model. The computational simulation results suggest that solid tumor geometry is related to the interstitial pressure, such that tumors with high interstitial pressure are more likely to develop dendritic structures than those with low interstitial pressure. PMID:24404145

Application of hydrometallurgy techniques in quartz processing and purification: a review

NASA Astrophysics Data System (ADS)

Lin, Min; Lei, Shaomin; Pei, Zhenyu; Liu, Yuanyuan; Xia, Zhangjie; Xie, Feixiang

2018-04-01

Although there have been numerous studies on separation and purification of metallic minerals by hydrometallurgy techniques, applications of the chemical techniques in separation and purification of non-metallic minerals are rarely reported. This paper reviews disparate areas of study into processing and purification of quartz (typical non-metallic ore) in an attempt to summarize current work, as well as to suggest potential for future consolidation in the field. The review encompasses chemical techniques of the quartz processing including situations, progresses, leaching mechanism, scopes of application, advantages and drawbacks of micro-bioleaching, high temperature leaching, high temperature pressure leaching and catalyzed high temperature pressure leaching. Traditional leaching techniques including micro-bioleaching and high temperature leaching are unequal to demand of modern glass industry for quality of quartz concentrate because the quartz products has to be further processed. High temperature pressure leaching and catalyzed high temperature pressure leaching provide new ways to produce high-grade quartz sand with only one process and lower acid consumption. Furthermore, the catalyzed high temperature pressure leaching realizes effective purification of quartz with extremely low acid consumption (no using HF or any fluoride). It is proposed that, by integrating the different chemical processes of quartz processing and expounding leaching mechanisms and scopes of application, the research field as a monopolized industry would benefit.

Does pressure cause liver cirrhosis? The sinusoidal pressure hypothesis.

PubMed

Mueller, Sebastian

2016-12-28

Independent of their etiology, all chronic liver diseases ultimately lead to liver cirrhosis, which is a major health problem worldwide. The underlying molecular mechanisms are still poorly understood and no efficient treatment strategies are available. This paper introduces the sinusoidal pressure hypothesis (SPH), which identifies an elevated sinusoidal pressure (SP) as cause of fibrosis. SPH has been mainly derived from recent studies on liver stiffness. So far, pressure changes have been exclusively seen as a consequence of cirrhosis. According to the SPH, however, an elevated SP is the major upstream event that initiates fibrosis via biomechanic signaling by stretching of perisinusoidal cells such as hepatic stellate cells or fibroblasts (SPH part I: initiation). Fibrosis progression is determined by the degree and time of elevated SP. The SPH predicts that the degree of extracellular matrix eventually matches SP with critical thresholds > 12 mmHg and > 4 wk. Elevated arterial flow and final arterialization of the cirrhotic liver represents the self-perpetuating key event exposing the low-pressure-organ to pathologically high pressures (SPH part II: perpetuation). It also defines the "point of no return" where fibrosis progression becomes irreversible. The SPH is able to explain the macroscopic changes of cirrhotic livers and the uniform fibrotic response to various etiologies. It also opens up new views on the role of fat and disease mechanisms in other organs. The novel concept will hopefully stimulate the search for new treatment strategies.

Islet amyloid polypeptide and high hydrostatic pressure: towards an understanding of the fibrillization process

NASA Astrophysics Data System (ADS)

Lopes, D. H. J.; Smirnovas, V.; Winter, R.

2008-07-01

Type II Diabetes Mellitus is a disease which is characterized by peripheral insulin resistance coupled with a progressive loss of insulin secretion that is associated with a decrease in pancreatic islet β-cell mass and the deposition of amyloid in the extracellular matrix of β-cells, which lead to islet cell death. The principal component of the islet amyloid is a pancreatic hormone called islet amyloid polypeptide (IAPP). High-pressure coupled with FT-IR, CD, ThT fluorescence spectroscopic and AFM studies were carried out to reveal information on the aggregation pathway as well as the aggregate structure of IAPP. Our data indicate that IAPP pre-formed fibrils exhibit a strong polymorphism with heterogeneous structures very sensitive to high hydrostatic pressure, indicating a high percentage of ionic and hydrophobic interactions being responsible for the stability the IAPP fibrils.

Studies of discharge mechanisms in high pressure gases-applications to high efficiency high power lasers. Ph.D. Thesis. Semiannual Progress Report

NASA Technical Reports Server (NTRS)

Cherrington, B. E.; Verdeyen, J. T.; Eden, J. G.; Leslie, S. G.

1975-01-01

By measuring the absorption and emission cantinua of various states in the cesium/xenon molecule, the collisional rates critical in populating the alkali/rare gas excimer levels have been estimated. Cs atomic states that are weakly optically connected to ground have been shown to form excimer levels that are attractive as potential dissociation lasers. In particular, the (Cs/7 2S/Xe) excited molecule appears promising as a source of high energy laser radiation due to its large dissociation energy, stimulated emission cross section, and small population inversion densities. Monitoring of the optically pumped Cs2 molecular absorption profile in the presence of xenon shows a drastic change with increasing xenon pressure for the Cs2C band. Dominant absorption at large xenon densities is centered around approximately 6380 A as opposed to 6300 A for lower perturber pressure.

Work Capability and physiological effects predictive studies. 4: In He-O2 excursions to pressures of 400- 800- 1200- and 1600 feet of sea water

NASA Technical Reports Server (NTRS)

Lambertsen, C. J. (Editor); Gelfand, R. (Editor); Clark, J. M. (Editor); Fletcher, M. E. (Editor)

1978-01-01

Experiments which exposed men in chambers, breathing helium with oxygen, to progressive increases of pressure equivalent to 400-800-1200-1600 feet of sea water (fsw) were conducted. Rates of compression and exposure to stable high pressure. Goals included: 1) determination of the specific character and time course of onset of physiological and performance decrements during the intentionally rapid compressions, and determination of rates of adaptation on reaching stable elevated pressure; 2) investigation of accelerated methods for decompression in deep saturation excursion diving; and 3) determination of competence in practical work performed in water at pressures equivalent to the extreme diving depths of 1200 and 1600 fsw.

Recent Progress in Electronic Skin

PubMed Central

Wang, Xiandi; Dong, Lin; Zhang, Hanlu; Yu, Ruomeng; Wang, Zhong Lin

2015-01-01

The skin is the largest organ of the human body and can sense pressure, temperature, and other complex environmental stimuli or conditions. The mimicry of human skin's sensory ability via electronics is a topic of innovative research that could find broad applications in robotics, artificial intelligence, and human–machine interfaces, all of which promote the development of electronic skin (e‐skin). To imitate tactile sensing via e‐skins, flexible and stretchable pressure sensor arrays are constructed based on different transduction mechanisms and structural designs. These arrays can map pressure with high resolution and rapid response beyond that of human perception. Multi‐modal force sensing, temperature, and humidity detection, as well as self‐healing abilities are also exploited for multi‐functional e‐skins. Other recent progress in this field includes the integration with high‐density flexible circuits for signal processing, the combination with wireless technology for convenient sensing and energy/data transfer, and the development of self‐powered e‐skins. Future opportunities lie in the fabrication of highly intelligent e‐skins that can sense and respond to variations in the external environment. The rapidly increasing innovations in this area will be important to the scientific community and to the future of human life. PMID:27980911

Microbial Evolution at High Pressure: Deep Sea and Laboratory Studies

NASA Astrophysics Data System (ADS)

Bartlett, D. H.

2011-12-01

Elevated hydrostatic pressures are present in deep-sea and deep-Earth environments where this physical parameter has influenced the evolution and characteristics of life. Piezophilic (high-pressure-adapted) microbes have been isolated from diverse deep-sea settings, and would appear likely to occur in deep-subsurface habitats as well. In order to discern the factors enabling life at high pressure my research group has explored these adaptations at various levels, most recently including molecular analyses of deep-sea trench communities, and through the selective evolution of the model microbe Escherichia coli in the laboratory to progressively higher pressures. Much of the field work has focused on the microbes present in the deeper portions of the Puerto Rico Trench (PRT)and in the Peru-Chile Trench (PCT), from 6-8.5 km below the sea surface (~60-85 megapascals pressure). Culture-independent phylogenetic data on the Bacteria and Archaea present on particles or free-living, along with data on the microeukarya present was complemented with genomic analyses and the isolation and characterization of microbes in culture. Metagenomic analyses of the PRT revealed increased genome sizes and an overrepresentation at depth of sulfatases for the breakdown of sulfated polysaccharides and specific categories of transporters, including those associated with the transport of diverse cations or carboxylate ions, or associated with heavy metal resistance. Single-cell genomic studies revealed several linneages which recruited to the PRT metagenome far better than existing marine microbial genome sequences. analyses. Novel high pressure culture approaches have yielded new piezophiles including species preferring very low nutrient levels, those living off of hydrocarbons, and those adapted to various electron donor/electron acceptor combinations. In order to more specifically focus on functions enabling life at increased pressure selective evolution experiments were performed with Escherichia coli during laboratory cultivation. More than 60 subcultures were obtained at progressively increasing hydrostatic pressures ranging from 28 - 62 megapascals. A strain isolated from the 63rd subculture displayed dramatically improved growth over the parental strain at 59 megapascals but reduced growth rate relative to the parental strain at atmospheric pressure. The mutant also produced far more unsaturated fatty acids than its parent and also acquired the ability to upregulate these fatty acids species at elevated pressure. Solexa sequencing revealed mutations within an operon (acpP operon) governing unsaturated fatty acid production, and these have been examined as a function of generation at high pressure. These and other results indicate that a large number and variety of microbes are adapted to life at high pressure, that the selective constraints of pressure increases up to ~60 megapascals are not so severe as to preclude the rapid evolution to a piezotolerant phenotype, and that the production of increased levels of unsaturated fatty acids correlates with adaptation to this stressor. This work was supported by grants from the National Science Foundation (EF-0801793 and EF-0827051) and the National Aeronautics and Space Administration (NASA SSC NNX10AR13G).

Evaluation of Progressive Failure Analysis and Modeling of Impact Damage in Composite Pressure Vessels

NASA Technical Reports Server (NTRS)

Sanchez, Christopher M.

2011-01-01

NASA White Sands Test Facility (WSTF) is leading an evaluation effort in advanced destructive and nondestructive testing of composite pressure vessels and structures. WSTF is using progressive finite element analysis methods for test design and for confirmation of composite pressure vessel performance. Using composite finite element analysis models and failure theories tested in the World-Wide Failure Exercise, WSTF is able to estimate the static strength of composite pressure vessels. Additionally, test and evaluation on composites that have been impact damaged is in progress so that models can be developed to estimate damage tolerance and the degradation in static strength.

HIT collaborative base project at APS of Argonne

NASA Astrophysics Data System (ADS)

Liu, H.; Wang, L.

2012-12-01

Harbin Institute of Technology (HIT) launched collaborative base project at Argonne National Laboratory in 2010, and progress will be presented in this paper. The staff and students from HIT involved in advanced technological developments, which included tomography. high energy PDF, diffraction and scattering, and inelastic scattering techniques in APS to study structures changes under high pressure conditions.

Ultrahigh-Sensitivity Piezoresistive Pressure Sensors for Detection of Tiny Pressure.

PubMed

Li, Hongwei; Wu, Kunjie; Xu, Zeyang; Wang, Zhongwu; Meng, Yancheng; Li, Liqiang

2018-06-20

High-sensitivity pressure sensors are crucial for the ultrasensitive touch technology and E-skin, especially at the tiny-pressure range below 100 Pa. However, it is highly challenging to substantially promote sensitivity beyond the current level at several to 200 kPa -1 and to improve the detection limit lower than 0.1 Pa, which is significant for the development of pressure sensors toward ultrasensitive and highly precise detection. Here, we develop an efficient strategy to greatly improve the sensitivity near to 2000 kPa -1 using short-channel coplanar device structure and sharp microstructure, which is systematically proposed for the first time and rationalized by the mathematic calculation and analysis. Significantly, benefiting from the ultrahigh sensitivity, the detection limit is improved to be as small as 0.075 Pa. The sensitivity and detection limit are both superior to the current levels and far surpass the function of human skin. Furthermore, the sensor shows fast response time (50 μs), excellent reproducibility and stability, and low power consumption. Remarkably, the sensor shows excellent detection capacity in the tiny-pressure range, including light-emitting diode switching with a pressure of 7 Pa, ringtone (2-20 Pa) recognition, and ultrasensitive (0.1 Pa) electronic glove. This work represents a performance and strategic progress in the field of pressure sensing.

Report on ISS O2 Production, Gas Supply and Partial Pressure Management

NASA Technical Reports Server (NTRS)

Schaezler, Ryan N.; Cook, Anthony J.

2015-01-01

Oxygen is used on International Space Station (ISS) for metabolic support and denitrogenation procedures prior to Extra-Vehicular Activities. Nitrogen is used to maintain total pressure and account for losses associated with leakage and operational losses. Oxygen and nitrogen have been supplied by various visiting vehicles such as the Progress and Shuttle in addition to the on-orbit oxygen production capability. Starting in 2014, new high pressure oxygen/nitrogen tanks are available to launch on commercial cargo vehicles and will replace the high pressure gas source that Shuttle used to provide. To maintain a habitable atmosphere the oxygen and nitrogen partial pressures are controlled between upper and lower bounds. The full range of the allowable partial pressures along with the increased ISS cabin volume are utilized as a buffer allowing days to pass between oxygen production or direct addition of oxygen and nitrogen to the atmosphere from reserves. This paper summarizes the amount of gas supplied and produced from all of the sources and describes past experience of managing partial pressures along with the range of management options available to the ISS.

Association Between Early Life Growth and Blood Pressure Trajectories in Black South African Children.

PubMed

Kagura, Juliana; Adair, Linda S; Munthali, Richard J; Pettifor, John M; Norris, Shane A

2016-11-01

Early growth is associated with blood pressure measured on one occasion, but whether early life growth patterns are associated with longitudinal blood pressure trajectories is under-researched. Therefore, we sought to examine the association between early growth and blood pressure trajectories from childhood to adulthood. Blood pressure was measured on 7 occasions between ages 5 and 18 years in the Birth to Twenty cohort study, and conditional variables for growth in infancy and mid-childhood were computed from anthropometric measures (n=1937, 52% girls). We used a group-based trajectory modeling approach to identify distinct height-adjusted blood pressure trajectories and then tested their association with growth between birth and mid-childhood adjusting for several covariates. Three trajectory groups were identified for systolic and diastolic blood pressure: lower, middle, and upper in boys and girls, separately. In boys, predictors of the middle or upper systolic blood pressure trajectories versus the lower trajectory were in birth weight (odds ratio 0.75 [95% confidence interval 0.58-0.96] per SD) and relative weight gain in infancy (4.11 [1.25-13.51] per SD). In girls, greater relative weight gain and linear growth in both infancy and mid-childhood were consistently associated with an almost 2-fold higher likelihood of being in the upper versus lower systolic blood pressure trajectory. The associations for the diastolic blood pressure trajectories were inconsistent. These findings emphasize the importance of identifying children at risk of progression to high blood pressure. Accelerated growth in infancy and mid-childhood may be a key target for early life intervention in prevention of elevated blood pressure progression. © 2016 American Heart Association, Inc.

High pressure study of a highly energetic nitrogen-rich carbon nitride, cyanuric triazide

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

Laniel, Dominique; Desgreniers, Serge; Downie, Laura E.

Cyanuric triazide (CTA), a nitrogen-rich energetic material, was compressed in a diamond anvil cell up to 63.2 GPa. Samples were characterized by x-ray diffraction, Raman, and infrared spectroscopy. A phase transition occurring between 29.8 and 30.7 GPa was found by all three techniques. The bulk modulus and its pressure derivative of the low pressure phase were determined by fitting the 300 K isothermal compression data to the Birch-Murnaghan equation of state. Due to the strong photosensitivity of CTA, synchrotron generated x-rays and visible laser radiation both lead to the progressive conversion of CTA into a two dimensional amorphous C=N network,more » starting from 9.2 GPa. As a result of the conversion, increasingly weak and broad x-ray diffraction lines were recorded from crystalline CTA as a function of pressure. Hence, a definite structure could not be obtained for the high pressure phase of CTA. Results from infrared spectroscopy carried out to 40.5 GPa suggest the high pressure formation of a lattice built of tri-tetrazole molecular units. The decompression study showed stability of the high pressure phase down to 13.9 GPa. Finally, two CTA samples, one loaded with neon and the other with nitrogen, used as pressure transmitting media, were laser-heated to approximately 1100 K and 1500 K while compressed at 37.7 GPa and 42.0 GPa, respectively. In both cases CTA decomposed resulting in amorphous compounds, as recovered at ambient conditions.« less

Impact of masked hypertension on diabetic nephropathy in patients with type II diabetes: a KAMOGAWA-HBP study.

PubMed

Ushigome, Emi; Oyabu, Chikako; Tanaka, Toru; Hasegawa, Goji; Ohnishi, Masayoshi; Tsunoda, Sei; Ushigome, Hidetaka; Yokota, Isao; Nakamura, Naoto; Oda, Yohei; Asano, Mai; Tanaka, Muhei; Yamazaki, Masahiro; Fukui, Michiaki

2018-05-01

The prognostic significance of masked hypertension (MH) on the progression of diabetic nephropathy among patients with type II diabetes is not well documented. We examined the relationship between clinic systolic blood pressure (SBP) and morning home SBP measurements and progression to macroalbuminuria in patients with type II diabetes. We analyzed prospective cohort study data from 712 patients with type II diabetes. We classified the patients into the following four groups according to their clinic (130 mm Hg) and home (125 mm Hg) SBP measurements: controlled blood pressure group, white-coat hypertension group, MH group, and sustained hypertension (SH) group. The patients were instructed to perform triplicate morning and evening blood pressure measurements for 14 consecutive days. During the 2-year follow-up period, 23 patients progressed to macroalbuminuria. The unadjusted odds ratio (95% confidence interval) for progression to macroalbuminuria among the patients with MH was significantly higher than that among the patients with controlled blood pressure (8.89 [1.06-74.88]). No significant relationship was observed between white-coat hypertension or SH and progression to macroalbuminuria. In analyses adjusted for various potential confounders, the adjusted odds ratio for progression to macroalbuminuria in the MH group was more than 8-fold higher than that in the controlled blood pressure group. MH might be a predictor of progression to macroalbuminuria among patients with type II diabetes. This rate of progression is comparable with or greater than the results reported for patients with SH. Copyright © 2018 American Society of Hypertension. Published by Elsevier Inc. All rights reserved.

Early episodes of high-pressure core formation preserved in plume mantle

NASA Astrophysics Data System (ADS)

Jackson, Colin R. M.; Bennett, Neil R.; Du, Zhixue; Cottrell, Elizabeth; Fei, Yingwei

2018-01-01

The decay of short-lived iodine (I) and plutonium (Pu) results in xenon (Xe) isotopic anomalies in the mantle that record Earth’s earliest stages of formation. Xe isotopic anomalies have been linked to degassing during accretion, but degassing alone cannot account for the co-occurrence of Xe and tungsten (W) isotopic heterogeneity in plume-derived basalts and their long-term preservation in the mantle. Here we describe measurements of I partitioning between liquid Fe alloys and liquid silicates at high pressure and temperature and propose that Xe isotopic anomalies found in modern plume rocks (that is, rocks with elevated 3He/4He ratios) result from I/Pu fractionations during early, high-pressure episodes of core formation. Our measurements demonstrate that I becomes progressively more siderophile as pressure increases, so that portions of mantle that experienced high-pressure core formation will have large I/Pu depletions not related to volatility. These portions of mantle could be the source of Xe and W anomalies observed in modern plume-derived basalts. Portions of mantle involved in early high-pressure core formation would also be rich in FeO, and hence denser than ambient mantle. This would aid the long-term preservation of these mantle portions, and potentially points to their modern manifestation within seismically slow, deep mantle reservoirs with high 3He/4He ratios.

Pressure induced coordination change of Al in silicate melts from Al K edge XANES of high pressure NaAlSi2O6-NaAlSi3O8 glasses

NASA Astrophysics Data System (ADS)

Li, Dien; Secco, R. A.; Bancroft, G. M.; Fleet, M. E.

Aluminum K-edge XANES spectra of high pressure and high temperature (4.4 GPa and 1575°C) glasses along the NaAlSi2O6 (Jd)-NaAlSi3O8 (Ab) join are reported using synchrotron radiation, and shown to provide direct experimental evidence for the pressure-induced coordination change of Al. Five- and six-fold coordinated Al (5Al and 6Al), characterized by Al K-edge positions at 1567.8 and 1568.7 eV, respectively, first appear in glass of composition Jd60Ab40 and increase in proportion progressively with increasing Jd content. The end-member jadeite glass contains about 6% of each of 5Al and 6Al. The present direct measurements confirm literature suggestions for the important role of Al in controlling viscosity and diffusion in mantle melts.

Arsenolite: a quasi-hydrostatic solid pressure-transmitting medium.

PubMed

Sans, J A; Manjón, F J; Popescu, C; Muñoz, A; Rodríguez-Hernández, P; Jordá, J L; Rey, F

2016-11-30

This study reports the experimental characterization of the hydrostatic properties of arsenolite (As4O6), a molecular solid which is one of the softest minerals in the absence of hydrogen bonding. The high compressibility of arsenolite and its stability up to 15 GPa have been proved by x-ray diffraction measurements, and the progressive loss of hydrostaticity with increasing pressure up to 20 GPa has been monitored by ruby photoluminescence. Arsenolite has been found to exhibit hydrostatic behavior up to 2.5 GPa and a quasi-hydrostatic behavior up to 10 GPa at room temperature. This result opens the way to explore other molecular solids as possible quasi-hydrostatic pressure-transmitting media. The validity of arsenolite as an insulating, stable, non-penetrating and quasi-hydrostatic medium is explored by the study of the x-ray diffraction of zeolite ITQ-29 at high pressure.

Pressure profiles of sport compression stockings.

PubMed

Reich-Schupke, Stefanie; Surhoff, Stefan; Stücker, Markus

2016-05-01

While sport compression stockings (SCS) have become increasingly popular, there is no regulatory norm as exists for medical compression stockings (MCS). The objective of this pilot study was to compare five SCS with respect to their pressure profiles ex vivo and in vivo, and in relation to German standards for MCS (RAL norm). In vivo (10 competitive athletes; standardized procedure using the Kikuhime pressure monitor) and ex vivo (tested at the Hohenstein Institute) pressure profiles were tested for the following products: CEP Running Progressive Socks, Falke Running Energizing, Sigvaris Performance, X-Socks Speed Metal Energizer, and 2XU Compression Race Socks. Ex vivo ankle pressures of CEP (25.6 mmHg) and 2XU (23.2 mmHg) corresponded to class 2 MCS; that of Sigvaris (20.8 mmHg), to class 1 MCS. The remaining SCS achieved lower pressure values. The pressure gradients showed marked differences, and did not meet MCS standards. Average in vivo pressures were higher for 2XU, CEP, and Sigvaris than for Falke and X-Socks. However, in vivo values for all SCS were below those of class 1 MCS. None of the SCS showed the decreasing pressure gradient (from distal to proximal) required for MCS. In vivo and ex vivo pressure profiles of all SCS examined showed marked heterogeneity, and did not meet MCS standards. Consequently, the clinical and practical effects of SCS cannot be compared, either. It would therefore be desirable to establish a classification that allows for the categorization and comparison of various SCS as well as their selection based on individual preferences and needs (high vs. low pressure, progressive vs. degressive profile). © 2016 Deutsche Dermatologische Gesellschaft (DDG). Published by John Wiley & Sons Ltd.

A High Pressure Post-Perovskite Phase Transition in NaMgF3--a MgSiO3 Analog Material

NASA Astrophysics Data System (ADS)

Martin, C.; Liu, H.; Crichton, W.; Parise, J. B.

2005-12-01

Since Murakami et al. (2004) identified a perovskite (pv, Pbnm) to post-perovskite (ppv, Cmcm) structural phase transition in MgSiO3, the transition has been reported to occur in many oxides at ultra-high pressures (>60 GPa). The layered ppv structure is rapidly shaping a better understanding of seismic anisotropy in the controversial D" region of the lower mantle. While the ppv unit cell may be derived from indexing of the powder pattern, the structure adopted at high pressure is experimentally ill-constrained due to compromised powder diffraction statistics typically obtained from small sample volumes at extreme conditions in the diamond anvil cell. NaMgF3, a structural analog material to MgSiO3 pv, exhibits a large compressibility and presents the possibility of reducing the pv-ppv transition pressure, allowing for improved powder statistics from a larger sample volume. In accordance with our previous theoretical and experimental evidence (Liu et al., 2005; Parise et al., 2004), we have observed a phase transition in NaMgF3 during two recent independent high pressure trials utilizing monochromatic x-ray diffraction and in-situ laser heating in the diamond anvil cell at pressures as low as 30 GPa. From our analysis thus far, we have found the unit cell of the high pressure phase cannot be indexed according to pv (Pbnm) or close permutations of ppv (Cmcm) unit cells predicted for NaMgF3 or unit cells observed for ppv MgSiO3 and MgGeO3. In addition, we have precluded a breakdown to high pressure phases of NaF and MgF3 as an explanation for the observed data. Upon pressure release, we observe diffraction peaks from the high pressure phase in the absence of pv NaMgF3, suggesting the high pressure structure is quenchable to ambient conditions. The results of the work in progress will be presented at the meeting.

Effects of medical therapies on retinopathy progression in type 2 diabetes.

PubMed

Chew, Emily Y; Ambrosius, Walter T; Davis, Matthew D; Danis, Ronald P; Gangaputra, Sapna; Greven, Craig M; Hubbard, Larry; Esser, Barbara A; Lovato, James F; Perdue, Letitia H; Goff, David C; Cushman, William C; Ginsberg, Henry N; Elam, Marshall B; Genuth, Saul; Gerstein, Hertzel C; Schubart, Ulrich; Fine, Lawrence J

2010-07-15

We investigated whether intensive glycemic control, combination therapy for dyslipidemia, and intensive blood-pressure control would limit the progression of diabetic retinopathy in persons with type 2 diabetes. Previous data suggest that these systemic factors may be important in the development and progression of diabetic retinopathy. In a randomized trial, we enrolled 10,251 participants with type 2 diabetes who were at high risk for cardiovascular disease to receive either intensive or standard treatment for glycemia (target glycated hemoglobin level, <6.0% or 7.0 to 7.9%, respectively) and also for dyslipidemia (160 mg daily of fenofibrate plus simvastatin or placebo plus simvastatin) or for systolic blood-pressure control (target, <120 or <140 mm Hg). A subgroup of 2856 participants was evaluated for the effects of these interventions at 4 years on the progression of diabetic retinopathy by 3 or more steps on the Early Treatment Diabetic Retinopathy Study Severity Scale (as assessed from seven-field stereoscopic fundus photographs, with 17 possible steps and a higher number of steps indicating greater severity) or the development of diabetic retinopathy necessitating laser photocoagulation or vitrectomy. At 4 years, the rates of progression of diabetic retinopathy were 7.3% with intensive glycemia treatment, versus 10.4% with standard therapy (adjusted odds ratio, 0.67; 95% confidence interval [CI], 0.51 to 0.87; P=0.003); 6.5% with fenofibrate for intensive dyslipidemia therapy, versus 10.2% with placebo (adjusted odds ratio, 0.60; 95% CI, 0.42 to 0.87; P=0.006); and 10.4% with intensive blood-pressure therapy, versus 8.8% with standard therapy (adjusted odds ratio, 1.23; 95% CI, 0.84 to 1.79; P=0.29). Intensive glycemic control and intensive combination treatment of dyslipidemia, but not intensive blood-pressure control, reduced the rate of progression of diabetic retinopathy. (Funded by the National Heart, Lung, and Blood Institute and others; ClinicalTrials.gov numbers, NCT00000620 for the ACCORD study and NCT00542178 for the ACCORD Eye study.) 2010 Massachusetts Medical Society

Pressure-induced amorphization of charge ordered spinel AlV{sub 2}O{sub 4} at low temperature

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

Malavi, Pallavi S., E-mail: malavips@barc.gov.in; Karmakar, S., E-mail: malavips@barc.gov.in; Sharma, S. M.

2014-04-24

Structural properties of charge ordered spinel AlV{sub 2}O{sub 4} have been investigated under high pressure at low temperature (80K) by synchrotron based x-ray diffraction measurements. It is observed that upon increasing pressure the structure becomes progressively disordered due to the distortion of the AlO{sub 4} tetrahedral unit and undergoes amorphization above ∼12 GPa. While releasing pressure, the rhombohedral phase is only partially recovered at a much lower pressure (below 5 GPa). Within the stability of the rhombohedral phase, the distortion in the vanadium heptamer increases monotonically with pressure, suggesting enhanced charge ordering. This result is in sharp contrast with themore » recent observation of pressure-induced frustration in the charge ordered state leading to structural transition to the cubic phase at room temperature [JPCM 25, 292201, 2013].« less

Morale of Teachers in High Poverty Schools: A Post-NCLB Mixed Methods Analysis

ERIC Educational Resources Information Center

Byrd-Blake, Marie; Afolayan, Michael O.; Hunt, John W.; Fabunmi, Martins; Pryor, Brandt W.; Leander, Robert

2010-01-01

This study tested how well Fishbein and Ajzen's Theory of Reasoned Action predicted the attitudes and morale of urban teachers in high poverty schools under the pressures of the No Child Left Behind Act (NCLB). NCLB forced local administrators to target schools that had not made adequately yearly progress (AYP) for two or more consecutive years.…

The Role of Districts in Fostering Instructional Improvement Lessons from Three Urban Districts Partnered with the Institute for Learning

ERIC Educational Resources Information Center

Marsh, Julie A.; Kerr, Kerri A.; Ikemoto, Gina S.; Darilek, Hilary; Suttorp, Marika; Zimmer, Ron W.; Barney, Heather

2005-01-01

The current high-stakes accountability environment brought on by the federal No Child Left Behind Act (NCLB) places great pressure on school districts to demonstrate success by meeting yearly progress goals for student achievement and eventually demonstrating that all students achieve at high standards. In particular, many urban school…

Supercritical droplet combustion and related transport phenomena

NASA Technical Reports Server (NTRS)

Yang, Vigor; Hsieh, K. C.; Shuen, J. S.

1993-01-01

An overview of recent advances in theoretical analyses of supercritical droplet vaporization and combustion is conducted. Both hydrocarbon and cryogenic liquid droplets over a wide range of thermodynamic states are considered. Various important high-pressure effects on droplet behavior, such as thermodynamic non-ideality, transport anomaly, and property variation, are reviewed. Results indicate that the ambient gas pressure exerts significant control of droplet gasification and burning processes through its influence on fluid transport, gas-liquid interfacial thermodynamics, and chemical reactions. The droplet gasification rate increases progressively with pressure. However, the data for the overall burnout time exhibit a considerable change in the combustion mechanism at the criticl pressure, mainly as a result of reduced mass diffusivity and latent heat of vaporization with increased pressure. The influence of droplet size on the burning characteristics is also noted.

High-Energy Electron Confinement in a Magnetic Cusp Configuration

NASA Astrophysics Data System (ADS)

Park, Jaeyoung; Krall, Nicholas A.; Sieck, Paul E.; Offermann, Dustin T.; Skillicorn, Michael; Sanchez, Andrew; Davis, Kevin; Alderson, Eric; Lapenta, Giovanni

2015-04-01

We report experimental results validating the concept that plasma confinement is enhanced in a magnetic cusp configuration when β (plasma pressure/magnetic field pressure) is of order unity. This enhancement is required for a fusion power reactor based on cusp confinement to be feasible. The magnetic cusp configuration possesses a critical advantage: the plasma is stable to large scale perturbations. However, early work indicated that plasma loss rates in a reactor based on a cusp configuration were too large for net power production. Grad and others theorized that at high β a sharp boundary would form between the plasma and the magnetic field, leading to substantially smaller loss rates. While not able to confirm the details of Grad's work, the current experiment does validate, for the first time, the conjecture that confinement is substantially improved at high β . This represents critical progress toward an understanding of the plasma dynamics in a high-β cusp system. We hope that these results will stimulate a renewed interest in the cusp configuration as a fusion confinement candidate. In addition, the enhanced high-energy electron confinement resolves a key impediment to progress of the Polywell fusion concept, which combines a high-β cusp configuration with electrostatic fusion for a compact, power-producing nuclear fusion reactor.

Review on recent research progress on laser power measurement based on light pressure

NASA Astrophysics Data System (ADS)

Lai, WenChang; Zhou, Pu

2018-03-01

Accurate measuring the laser power is one of the most important issue to evaluate the performance of high power laser. For the time being, most of the demonstrated technique could be attributed to direct measuring route. Indirect measuring laser power based on light pressure, which has been under intensive investigation, has the advantages such as fast response, real-time measuring and high accuracy, compared with direct measuring route. In this paper, we will review several non-traditional methods based on light pressure to precisely measure the laser power proposed recently. The system setup, measuring principle and scaling methods would be introduced and analyzed in detail. We also compare the benefit and the drawback of these methods and analyze the uncertainties of the measurements.

Burn Treatment: Annual Research Progress Report.

DTIC Science & Technology

1975-06-30

in addition to direct or indirect measurements of blood pressure. Central venous pressures are measured relatively frequently and, on occasion, a... Central venous pressure assessment. 5. EKG. 46 I 6. Sponge weighing. 7. Measurement of urine output during surgery. B. RESPIRATION 1. Counting of...start a central venous line prior to adminis- tration of vasopressors. The patient became progressively more hypo- tensive and bradycardiac, which

Inner-shell chemistry under high pressure

NASA Astrophysics Data System (ADS)

Miao, Maosheng; Botana, Jorge; Pravica, Michael; Sneed, Daniel; Park, Changyong

2017-05-01

Chemistry at ambient conditions has implicit boundaries rooted in the atomic shell structure: the inner-shell electrons and the unoccupied outer-shell orbitals do not contribute as the major component to chemical reactions and in chemical bonds. These general rules govern our understanding of chemical structures and reactions. We review the recent progresses in high-pressure chemistry demonstrating that the above rules can be violated under extreme conditions. Using a first principles computation method and crystal structure search algorithm, we demonstrate that stable compounds involving inner shell electrons such as CsF3, CsF5, HgF3, and HgF4 can form under high external pressure and may present exotic properties. We also discuss experimental studies that have sought to confirm these predictions. Employing our recently developed hard X-ray photochemistry methods in a diamond anvil cell, we show promising early results toward realizing inner shell chemistry experimentally.

Massive Bilateral Serous Retinal Detachment in a Case of Hypertensive Chorioretinopathy

PubMed Central

Villalba-Pinto, Luis; Hernández-Ortega, M. Ángeles; de los Mozos, F. Javier Lavid; Pascual-Camps, Isabel; Dolz-Marco, Rosa; Arevalo, J. Fernando; Gallego-Pinazo, Roberto

2014-01-01

Introduction Systemic high blood pressure is related to a variety of retinal manifestations. We present an atypical case of hypertensive chorioretinopathy with massive bilateral serous retinal detachment. Case Report A 26-year-old male with a genitourinary malformation and secondary grade IV chronic kidney failure as well as high blood pressure complained of acute vision loss. Dilated fundus examination evidenced a bilateral serous retinal detachment with macular involvement. The patient was unresponsive to oral antihypertensive therapy and dialysis treatment. The serous retinal detachment progressively decreased after the restoration of dialysis and antihypertensive therapy. The final visual acuity was 0.50 in both eyes. Discussion In cases of serous macular detachment, it is mandatory to rule out different systemic and ocular diseases. The presence of uncontrolled high blood pressure may produce aggressive bilateral retinal changes, thus hypertension must be under early and strict control in order to improve the visual outcomes. PMID:25120474

Does pressure cause liver cirrhosis? The sinusoidal pressure hypothesis

PubMed Central

Mueller, Sebastian

2016-01-01

Independent of their etiology, all chronic liver diseases ultimately lead to liver cirrhosis, which is a major health problem worldwide. The underlying molecular mechanisms are still poorly understood and no efficient treatment strategies are available. This paper introduces the sinusoidal pressure hypothesis (SPH), which identifies an elevated sinusoidal pressure (SP) as cause of fibrosis. SPH has been mainly derived from recent studies on liver stiffness. So far, pressure changes have been exclusively seen as a consequence of cirrhosis. According to the SPH, however, an elevated SP is the major upstream event that initiates fibrosis via biomechanic signaling by stretching of perisinusoidal cells such as hepatic stellate cells or fibroblasts (SPH part I: initiation). Fibrosis progression is determined by the degree and time of elevated SP. The SPH predicts that the degree of extracellular matrix eventually matches SP with critical thresholds > 12 mmHg and > 4 wk. Elevated arterial flow and final arterialization of the cirrhotic liver represents the self-perpetuating key event exposing the low-pressure-organ to pathologically high pressures (SPH part II: perpetuation). It also defines the “point of no return” where fibrosis progression becomes irreversible. The SPH is able to explain the macroscopic changes of cirrhotic livers and the uniform fibrotic response to various etiologies. It also opens up new views on the role of fat and disease mechanisms in other organs. The novel concept will hopefully stimulate the search for new treatment strategies. PMID:28082801

Glaucoma and Alzheimer Disease: A Single Age-Related Neurodegenerative Disease of the Brain.

PubMed

Mancino, Raffaele; Martucci, Alessio; Cesareo, Massimo; Giannini, Clarissa; Corasaniti, Maria Tiziana; Bagetta, Giacinto; Nucci, Carlo

2017-12-06

Open Angle Glaucoma is one of the leading causes of irreversible blindness worldwide. Elevated intraocular pressure is considered an important risk factor for glaucoma, however a subset of patients experience disease progression even in presence of normal intraocular pressure values. This implies that risk factors other than intraocular pressure are involved in the pathogenesis of glaucoma. A possible relationship between glaucoma and neurodegenerative diseases such as Alzheimer Disease has been suggested. In this regard, we have recently described a high prevalence of alterations typical of glaucoma, using Heidelberg Retinal Tomograph-3 (HRT-3), in a group of patients with Alzheimer Disease. Interestingly, these alterations were not associated with elevated intraocular pressure or abnormal Central Corneal Thickness values. Alzheimer Disease is the most common form of dementia associated with progressive deterioration of memory and cognition. Complaints related to vision are common among Alzheimer Disease patients. Features common to both diseases, including risk factors and pathophysiological mechanisms, gleaned from the recent literature do suggest that Alzheimer Disease and glaucoma can be considered age-related neurodegenerative diseases that may co-exist in the elderly. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Systolic hypertension and progression of aortic valve calcification in patients with aortic stenosis: results from the PROGRESSA study

PubMed Central

Tastet, Lionel; Capoulade, Romain; Clavel, Marie-Annick; Larose, Éric; Shen, Mylène; Dahou, Abdellaziz; Arsenault, Marie; Mathieu, Patrick; Bédard, Élisabeth; Dumesnil, Jean G.; Tremblay, Alexe; Bossé, Yohan; Després, Jean-Pierre; Pibarot, Philippe

2017-01-01

Aims Hypertension is highly prevalent in patients with aortic stenosis (AS) and is associated with worse outcomes. The current prospective study assessed the impact of systolic hypertension (SHPT) on the progression of aortic valve calcification (AVC) measured by multidetector computed tomography (MDCT) in patients with AS. Methods and results The present analysis includes the first series of 101 patients with AS prospectively recruited in the PROGRESSA study. Patients underwent comprehensive Doppler echocardiography and MDCT exams at baseline and after 2-year follow-up. AVC and coronary artery calcification (CAC) were measured using the Agatston method. Patients with SHPT at baseline (i.e. systolic blood pressure ≥140 mmHg; n = 37, 37%) had faster 2-year AVC progression compared with those without SHPT (i.e. systolic blood pressure <140 mmHg) (AVC median [25th percentile–75th percentile]: +370 [126–824] vs. +157 [58–303] AU; P = 0.007, respectively). Similar results were obtained with the analysis of AVC progression divided by the cross-sectional area of the aortic annulus (AVCdensity: +96 [34–218] vs. +45 [14–82] AU/cm2, P = 0.01, respectively). In multivariable analysis, SHPT remained significantly associated with faster progression of AVC or AVCdensity (all P = 0.001). There was no significant difference between groups with respect to progression of CAC (+39 [3–199] vs. +41 [0–156] AU, P = 0.88). Conclusion This prospective study shows for the first time that SHPT is associated with faster AVC progression but not with CAC progression in AS patients. These findings provide further support for the elaboration of randomized clinical trials to assess the efficacy of antihypertensive medication to slow the stenosis progression in patients with AS. PMID:26896413

Cryo-Compression System in a 3000 Ton Multi-Anvil Press

NASA Astrophysics Data System (ADS)

Secco, R. A.; Yong, W.

2016-12-01

Most large volume high pressure devices are capable of high temperature experiments that are typically achieved by using localized resistive heating of a metal foil, graphite or ceramic sleeve inside a thermally insulated sample volume in a high pressure cell. Low temperatures at high pressures are needed for physical property studies of materials that comprise planetary bodies in the outer solar system. However, low temperatures are more difficult to achieve mainly because the massive steel components of the press, which are in good thermal contact with each other under high load, act as large heat reservoirs and pathways that encumber the removal of heat from the pressure cell. We describe a new custom-designed system under development for a 3000 ton multi-anvil press to reach temperatures below 295K at high pressures. The system was designed to remove heat selectively and conductively from the sample volume through six of the eight WC cubes in direct contact with the octahedral pressure cell. Cooling fins made of Cu are sandwiched between, and in thermal contact with, neighboring anvil faces and are each connected to a dedicated Cu heat exchanger chamber through which liquid nitrogen flows. The chamber internal geometry consists of either square pillars that double the internal surface area of the rectangular parallelepiped enclosed volume or continuous walls separated by valleys. Gas from each chamber is vented to the lab through an exhaust pipe. High pressure results will be presented of several temperature monitoring points in the center of the pressure cell and on the surfaces of the WC cubes and steel wedges which recorded the time-dependent cooling progress. Temperature stability tests will also be presented.

Associations Between Cardiovascular Risk Factors, Inflammation, and Progression of Carotid Atherosclerosis Among Smokers.

PubMed

Zingg, Sarah; Collet, Tinh-Hai; Locatelli, Isabella; Nanchen, David; Depairon, Michèle; Bovet, Pascal; Cornuz, Jacques; Rodondi, Nicolas

2016-06-01

The high risk of cardiovascular events in smokers requires adequate control of other cardiovascular risk factors (CVRFs) to curtail atherosclerosis progression. However, it is unclear which CVRFs have the most influence on atherosclerosis progression in smokers. In 260 smokers aged 40-70 included in a smoking cessation trial, we analyzed the association between traditional CVRFs, high-sensitivity C-reactive protein (hs-CRP), smoking cessation and 3-year progression of carotid intima-media thickness (CIMT, assessed by repeated ultrasound measurements) in a longitudinal multivariate model. Participants (mean age 52 years, 47% women) had a mean smoking duration of 32 years with a median daily consumption of 20 cigarettes. Baseline CIMT was 1185 μm (95% confidence interval [CI]: 1082-1287) and increased by 93 μm (95% CI: 25-161) and 108 μm (95% CI: 33-183) after 1 and 3 years, respectively. Age, male sex, daily cigarette consumption, systolic blood pressure (SBP), but neither low-density lipoprotein cholesterol nor hs-CRP, were independently associated with baseline CIMT (all P ≤ .05). Baseline SBP, but neither low-density lipoprotein cholesterol nor hs-CRP, was associated with 3-year atherosclerosis progression (P = .01 at 3 years). The higher the SBP at baseline, the steeper was the CIMT increase over 3-year follow-up. We found an increase of 26 μm per each 10-mmHg raise in SBP at 1 year and an increase of 39 μm per each 10 mmHg raise in SBP at 3 years. Due to insufficient statistical power, we could not exclude an effect of smoking abstinence on CIMT progression. Control of blood pressure may be an important factor to limit atherosclerosis progression in smokers, besides support for smoking cessation. Among 260 smokers aged 40-70 years with a mean smoking duration of 32 years, baseline SBP was associated with atherosclerosis progression over 3 years, as measured by CIMT (P = .01 at 3 years), independently of smoking variables and other CVRFs. The higher the SBP at baseline, the steeper was the CIMT increase over 3-year follow-up. Our findings emphasize the importance of focusing not only on smoking cessation among smokers, but to simultaneously control other CVRFs, particularly blood pressure, in order to prevent future cardiovascular disease. © The Author 2015. Published by Oxford University Press on behalf of the Society for Research on Nicotine and Tobacco. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Experimental study of planetary gases with applications to planetary interior models

NASA Technical Reports Server (NTRS)

Bell, Peter M.; Mao, Ho-Kwang

1988-01-01

High-pressure experimental data on planetary materials are critical in developing planetary models and in addressing otherwise insoluble problems of the internal structure of the major planets. Progress in the last five years has been particularly marked. Maximum static pressure of 550 GPa was achieved. For the first time, X-ray diffraction of solidified gases (Ne, Xe) and ices (H2O) were obtained at pressures above one megabar, single-crystal diffraction of ultralight elements (H2, He) were detected up to 25 GPa, pressures over 200 GPa at 77 K were reached in solid hydrogen, including the discovery of a phase transformation in the molecular solid. Advances in instrumentation and new measurements performed during 1983 to 1988 are summarized.

Origin of superconductivity in KFe2As2 under positive and negative pressures and relation to other Fe-based families

NASA Astrophysics Data System (ADS)

Valenti, Roser

KFe2As2 shows an intricate behavior as a function of pressure. At ambient pressure the system is superconductor with a low critical temperature Tc=3.4 K and follows a V-shaped pressure dependence of Tc for moderate pressures with a local minimum at a pressure of 1.5 GPa. Under high pressures Pc=15 GPa, KFe2As2 exhibits a structural phase transition from a tetragonal to a collapsed tetragonal phase accompanied by a boost of the superconducting critical temperature up to 12 K. On the other hand, negative pressures realized through substitution of K by Cs or Rb decrease Tc down to 2.25K. In this talk we will discuss recent progress on the understanding of the microscopic origin of this pressure-dependent behavior by considering a combination of ab initio density functional theory with dynamical mean field theory and spin fluctuation theory calculations. We will argue that a Lifshitz transition associated with the structural collapse changes the pairing symmetry from d-wave (tetragonal) to s+/- (collapsed tetragonal) at high pressures while at ambient and negative pressures correlation effects appear to be detrimental for superconductivity. Further, we shall establish cross-links to the chalcogenide family, in particular FeSe under pressure. The Deutsche Forschungsgemeinschaft (DFG) is gratefully acknowledged for financial support.

Late Miocene-Pliocene Asian monsoon intensification linked to Antarctic ice-sheet growth

NASA Astrophysics Data System (ADS)

Ao, Hong; Roberts, Andrew P.; Dekkers, Mark J.; Liu, Xiaodong; Rohling, Eelco J.; Shi, Zhengguo; An, Zhisheng; Zhao, Xiang

2016-06-01

Environmental conditions in one of Earth's most densely populated regions, East Asia, are dominated by the monsoon. While Quaternary monsoon variability is reasonably well understood, pre-Quaternary monsoon variability and dynamics remain enigmatic. In particular, little is known about potential relationships between northern hemispheric monsoon response and major Cenozoic changes in Antarctic ice cover. Here we document long-term East Asian summer monsoon (EASM) intensification through the Late Miocene-Pliocene (∼8.2 to 2.6 Ma), and attribute this to progressive Antarctic glaciation. Our new high-resolution magnetic records of long-term EASM intensification come from the Late Miocene-Pliocene Red Clay sequence on the Chinese Loess Plateau; we identify underlying mechanisms using a numerical climate-model simulation of EASM response to an idealized stepwise increase in Antarctic ice volume. We infer that progressive Antarctic glaciation caused intensification of the cross-equatorial pressure gradient between an atmospheric high-pressure cell over Australia and a low-pressure cell over mid-latitude East Asia, as well as intensification of the cross-equatorial sea-surface temperature (SST) gradient. These combined atmospheric and oceanic adjustments led to EASM intensification. Our findings offer a new and more global perspective on the controls behind long-term Asian monsoon evolution.

Late Miocene-Pliocene Asian monsoon intensification linked to Antarctic ice-sheet growth

NASA Astrophysics Data System (ADS)

Ao, H.; Roberts, A. P.; Dekkers, M. J.; Liu, X.; Rohling, E. J.; Shi, Z.; An, Z.; Zhao, X.

2016-12-01

Environmental conditions in one of Earth's most densely populated regions, East Asia, are dominated by the monsoon. While Quaternary monsoon variability is reasonably well understood, pre-Quaternary monsoon variability and dynamics remain enigmatic. In particular, little is known about potential relationships between northern hemispheric monsoon response and major Cenozoic changes in Antarctic ice cover. Here we document long-term East Asian summer monsoon (EASM) intensification through the Late Miocene-Pliocene (˜8.2 to 2.6 Ma), and attribute this to progressive Antarctic glaciation. Our new high-resolution magnetic records of long-term EASM intensification come from the Late Miocene-Pliocene Red Clay sequence on the Chinese Loess Plateau; we identify underlying mechanisms using a numerical climate-model simulation of EASM response to an idealized stepwise increase in Antarctic ice volume. We infer that progressive Antarctic glaciation caused intensification of the cross-equatorial pressure gradient between an atmospheric high-pressure cell over Australia and a low-pressure cell over mid-latitude East Asia, as well as intensification of the cross-equatorial sea-surface temperature (SST) gradient. These combined atmospheric and oceanic adjustments led to EASM intensification. Our findings offer a new and more global perspective on the controls behind long-term Asian monsoon evolution.

A New Look at Instructional Leadership

ERIC Educational Resources Information Center

Gray, David

2009-01-01

The No Child Left Behind Act of 2001 is the federal government's most recent effort to influence curriculum in America's classrooms. Its requirements for high-stakes testing and Adequate Yearly Progress have put pressure on teachers and administrators to improve student achievement. Principals whose administrative training was grounded in a…

CAPILLARY ION CHROMATOGRAPHY WITH ON-LINE HIGH PRESSURE ELECTRODIALYTIC NAOH ELUENT PRODUCTION AND GRADIENT GENERATION. (R825344)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

Harbin Institute of Technology collaborative base project at APS of Argonne

NASA Astrophysics Data System (ADS)

Liu, H.; Liu, L. L.

2013-05-01

In this paper, the progress of Harbin Institute of Technology (HIT) collaborative base project, which was launched at Argonne National Laboratory in 2010, will be presented. The staff and students from HIT involved in advanced technological developments, which included tomography, high energy PDF, diffraction and scattering, and inelastic scattering techniques in APS to study structures changes of minerals and materials under high pressure conditions.

Integrated axial and tangential serpentine cooling circuit in a turbine airfoil

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

Lee, Ching-Pang; Jiang, Nan; Marra, John J

2015-05-05

A continuous serpentine cooling circuit forming a progression of radial passages (44, 45, 46, 47A, 48A) between pressure and suction side walls (52, 54) in a MID region of a turbine airfoil (24). The circuit progresses first axially, then tangentially, ending in a last radial passage (48A) adjacent to the suction side (54) and not adjacent to the pressure side (52). The passages of the axial progression (44, 45, 46) may be adjacent to both the pressure and suction side walls of the airfoil. The next to last radial passage (47A) may be adjacent to the pressure side wall andmore » not adjacent to the suction side wall. The last two radial passages (47A, 48A) may be longer along the pressure and suction side walls respectively than they are in a width direction, providing increased direct cooling surface area on the interiors of these hot walls.« less

A Binary Eutectic Mixture of TNAZ and R-Salt Explosives

NASA Astrophysics Data System (ADS)

Sandstrom, Mary; Manner, Virginia; Pemberton, Steven; Lloyd, Joseph; Tappan, Bryce

2011-06-01

TNAZ is a high performing explosive that is melt castable. However, the casting process can be problematic since TNAZ has a high vapor pressure exacerbated by a fairly high melting temperature. In order to mitigate the ill effects of its high vapor pressure, including a lower melting explosive was explored by making a series of mixtures of TNAZ and R-Salt. Initially, a eutectic temperature and composition was theoretically determined. Then a phase diagram was constructed from a series and mixtures by differential scanning calorimetery (DSC). The vapor pressure of the eutectic composition was determined by thermogravimetric analysis (TGA). Cylinder testing of the eutectic composition was carried out in copper tubes, 5'' long with 1/2 ``inner diameter and 1/16'' thick walls. The detonation velocity was measured using wire switches along the cylinder length and the expanding wall velocity was measured using PDV gauges. A rough evaluation of JWL equation-of-state parameters has been carried out. A more detailed evaluation is in progress.

Progression of Carotid Arterial Stiffness With Treatment of Hypertension Over 10 Years: The Multi-Ethnic Study of Atherosclerosis.

PubMed

Gepner, Adam D; Tedla, Yacob; Colangelo, Laura A; Tattersall, Matthew C; Korcarz, Claudia E; Kaufman, Joel D; Liu, Kiang; Burke, Gregory L; Shea, Steven; Greenland, Philip; Stein, James H

2017-01-01

Associations with antihypertensive medication classes and progression of arterial stiffness have not been studied in a prospective multiethnic cohort. All participants had hypertension at baseline, defined as blood pressure ≥140/90 mm Hg or use of antihypertensive medications. Medication use and blood pressure were assessed at 5 time points. Young's elastic modulus and distensibility coefficient of the right common carotid artery were obtained by ultrasound at baseline and after a mean (SD) follow-up period of 9.4 (0.5) years. Associations with changes in Young's elastic modulus and distensibility coefficient, baseline antihypertensive medication use, number of visits each medication class was reported, and blood pressure control (<140/90 mm Hg) were assessed using multiple linear regression models. At baseline, mean age of participants (n=1206) was 63.2 (9.0) years (55% female; 35% African American, 19% Hispanic, 12% Chinese). Mean systolic blood pressure was 136.5 (20.6) mm Hg. Greater progression of arterial stiffness was associated with older age, African American ethnicity, and baseline calcium channel blocker use. There were no other associations between changes in Young's elastic modulus or distensibility coefficient and use of other medication classes (all P>0.4). Achieving blood pressure control (<140/90 mm Hg) at all visits was associated with slower progression of arterial stiffness (Young's elastic modulus: β=-790.1 mm Hg, P=0.01; distensibility coefficient: β=7.34×10 - 4 mm Hg - 1 , P=0.001). Blood pressure control, rather than use of any particular antihypertensive medication class, was associated most strongly with slowing arterial stiffness progression. Over nearly a decade of follow-up, no consistent associations between any specific antihypertensive medication class and progressive carotid arterial stiffening were identified. © 2016 American Heart Association, Inc.

A priori and a posteriori analyses of the flamelet/progress variable approach for supersonic combustion

NASA Astrophysics Data System (ADS)

Saghafian, Amirreza; Pitsch, Heinz

2012-11-01

A compressible flamelet/progress variable approach (CFPV) has been devised for high-speed flows. Temperature is computed from the transported total energy and tabulated species mass fractions and the source term of the progress variable is rescaled with pressure and temperature. The combustion is thus modeled by three additional scalar equations and a chemistry table that is computed in a pre-processing step. Three-dimensional direct numerical simulation (DNS) databases of reacting supersonic turbulent mixing layer with detailed chemistry are analyzed to assess the underlying assumptions of CFPV. Large eddy simulations (LES) of the same configuration using the CFPV method have been performed and compared with the DNS results. The LES computations are based on the presumed subgrid PDFs of mixture fraction and progress variable, beta function and delta function respectively, which are assessed using DNS databases. The flamelet equation budget is also computed to verify the validity of CFPV method for high-speed flows.

High cost of stage IV pressure ulcers.

PubMed

Brem, Harold; Maggi, Jason; Nierman, David; Rolnitzky, Linda; Bell, David; Rennert, Robert; Golinko, Michael; Yan, Alan; Lyder, Courtney; Vladeck, Bruce

2010-10-01

The aim of this study was to calculate and analyze the cost of treatment for stage IV pressure ulcers. A retrospective chart analysis of patients with stage IV pressure ulcers was conducted. Hospital records and treatment outcomes of these patients were followed up for a maximum of 29 months and analyzed. Costs directly related to the treatment of pressure ulcers and their associated complications were calculated. Nineteen patients with stage IV pressure ulcers (11 hospital-acquired and 8 community-acquired) were identified and their charts were reviewed. The average hospital treatment cost associated with stage IV pressure ulcers and related complications was $129,248 for hospital-acquired ulcers during 1 admission, and $124,327 for community-acquired ulcers over an average of 4 admissions. The costs incurred from stage IV pressure ulcers are much greater than previously estimated. Halting the progression of early stage pressure ulcers has the potential to eradicate enormous pain and suffering, save thousands of lives, and reduce health care expenditures by millions of dollars. Copyright © 2010 Elsevier Inc. All rights reserved.

Energy efficient continuous flow ash lockhopper

NASA Technical Reports Server (NTRS)

Collins, Earl R., Jr. (Inventor); Suitor, Jerry W. (Inventor); Dubis, David (Inventor)

1989-01-01

The invention relates to an energy efficient continuous flow ash lockhopper, or other lockhopper for reactor product or byproduct. The invention includes an ash hopper at the outlet of a high temperature, high pressure reactor vessel containing heated high pressure gas, a fluidics control chamber having an input port connected to the ash hopper's output port and an output port connected to the input port of a pressure letdown means, and a control fluid supply for regulating the pressure in the control chamber to be equal to or greater than the internal gas pressure of the reactor vessel, whereby the reactor gas is contained while ash is permitted to continuously flow from the ash hopper's output port, impelled by gravity. The main novelty resides in the use of a control chamber to so control pressure under the lockhopper that gases will not exit from the reactor vessel, and to also regulate the ash flow rate. There is also novelty in the design of the ash lockhopper shown in two figures. The novelty there is the use of annular passages of progressively greater diameter, and rotating the center parts on a shaft, with the center part of each slightly offset from adjacent ones to better assure ash flow through the opening.

Physiological and psychological effects of forest therapy on middle-aged males with high-normal blood pressure.

PubMed

Ochiai, Hiroko; Ikei, Harumi; Song, Chorong; Kobayashi, Maiko; Takamatsu, Ako; Miura, Takashi; Kagawa, Takahide; Li, Qing; Kumeda, Shigeyoshi; Imai, Michiko; Miyazaki, Yoshifumi

2015-02-25

Time spent walking and relaxing in a forest environment ("forest bathing" or "forest therapy") has well demonstrated anti-stress effects in healthy adults, but benefits for ill or at-risk populations have not been reported. The present study assessed the physiological and psychological effects of forest therapy (relaxation and stress management activity in the forest) on middle-aged males with high-normal blood pressure. Blood pressure and several physiological and psychological indices of stress were measured the day before and approximately 2 h following forest therapy. Both pre- and post-treatment measures were conducted at the same time of day to avoid circadian influences. Systolic and diastolic blood pressure (BP), urinary adrenaline, and serum cortisol were all significantly lower than baseline following forest therapy (p<0.05). Subjects reported feeling significantly more "relaxed" and "natural" according to the Semantic Differential (SD) method. Profile of Mood State (POMS) negative mood subscale scores for "tension-anxiety," "confusion," and "anger-hostility," as well as the Total Mood Disturbance (TMD) score were significantly lower following forest therapy. These results highlight that forest is a promising treatment strategy to reduce blood pressure into the optimal range and possibly prevent progression to clinical hypertension in middle-aged males with high-normal blood pressure.

Decoding intravesical pressure from local field potentials in rat lumbosacral spinal cord

NASA Astrophysics Data System (ADS)

Im, Changkyun; Park, Hae Yong; Koh, Chin Su; Ryu, Sang Baek; Seo, In Seok; Kim, Yong Jung; Kim, Kyung Hwan; Shin, Hyung-Cheul

2016-10-01

Chronic monitoring of intravesical pressure is required to detect the onset of intravesical hypertension and the progression of a more severe condition. Recent reports demonstrate the bladder state can be monitored from the spiking activity of the dorsal root ganglia or lumbosacral spinal cord. However, one of the most serious challenges for these methods is the difficulty of sustained spike signal acquisition due to the high-electrode-location-sensitivity of spikes or neuro-degeneration. Alternatively, it has been demonstrated that local field potential recordings are less affected by encapsulation reactions or electrode location changes. Here, we hypothesized that local field potential (LFP) from the lumbosacral dorsal horn may provide information concerning the intravesical pressure. LFP and spike activities were simultaneously recorded from the lumbosacral spinal cord of anesthetized rats during bladder filling. The results show that the LFP activities carry significant information about intravesical pressure along with spiking activities. Importantly, the intravesical pressure is decoded from the power in high-frequency bands (83.9-256 Hz) with a substantial performance similar to that of the spike train decoding. These findings demonstrate that high-frequency LFP activity can be an alternative intravesical pressure monitoring signal, which could lead to a proper closed loop system for urinary control.

Exercise capacity and progression from prehypertension to hypertension.

PubMed

Faselis, Charles; Doumas, Michael; Kokkinos, John Peter; Panagiotakos, Demosthenes; Kheirbek, Raya; Sheriff, Helen M; Hare, Katherine; Papademetriou, Vasilios; Fletcher, Ross; Kokkinos, Peter

2012-08-01

Prehypertension is likely to progress to hypertension. The rate of progression is determined mostly by age and resting blood pressure but may also be attenuated by increased fitness. A graded exercise test was performed in 2303 men with prehypertension at the Veterans Affairs Medical Centers in Washington, DC. Four fitness categories were defined, based on peak metabolic equivalents (METs) achieved. We assessed the association between exercise capacity and rate of progression to hypertension (HTN). The median follow-up period was 7.8 years (mean (± SD) 9.2±6.1 years). The incidence rate of progression from prehypertension to hypertension was 34.4 per 1000 person-years. Exercise capacity was a strong and independent predictor of the rate of progression. Compared to the High-Fit individuals (>10.0 METs), the adjusted risk for developing HTN was 66% higher (hazard ratio, 1.66; 95% CI, 1.2 to 2.2; P=0.001) for the Low-Fit and, similarly, 72% higher (hazard ratio, 1.72; 95% CI, 1.2 to 2.3; P=0.001) for the Least-Fit individuals, whereas it was only 36% for the Moderate-Fit (hazard ratio, 1.36; 95% CI, 0.99 to 1.80; P=0.056). Significant predictors for the progression to HTN were also age (19% per 10 years), resting systolic blood pressure (16% per 10 mm Hg), body mass index (15.3% per 5 U), and type 2 diabetes mellitus (2-fold). In conclusion, an inverse, S-shaped association was shown between exercise capacity and the rate of progression from prehypertension to hypertension in middle-aged and older male veterans. The protective effects of fitness were evident when exercise capacity exceeded 8.5 METs. These findings emphasize the importance of fitness in the prevention of hypertension.

Intraocular Pressure Changes during Accommodation in Progressing Myopes, Stable Myopes and Emmetropes

PubMed Central

Jiang, Xiaodan; Hu, Xiaodan; Zhang, Mingzhou; Li, Xuemin

2015-01-01

Purpose To investigate the changes of intraocular pressure (IOP) induced by 3-diopter (3 D) accommodation in progressing myopes, stable myopes and emmetropes. Design Cross-sectional study. Participants 318 subjects including 270 myopes and 48 emmetropes. Methods 195 progressing myopes, 75 stable myopes and 48 emmetropes participated in this study. All subjects had their IOP measured using iCare rebound tonometer while accommodative stimuli of 0 D and 3 D were presented. Main Outcome Measures IOP values without accommodation and with 3 D accommodation were measured in all subjects. Baseline IOPs and IOP changes were compared within and between groups. Results There was no significant difference in IOPs between progressing myopes, stable myopes and emmetropes when no accommodation was induced (17.47±3.46, 16.62±2.98 and 16.80±3.62 respectively, p>0.05). IOP experienced an insignificantly slight decrease after 3 D accommodation in three groups (mean change -0.19±2.16, -0.03±1.68 and -0.39±2.65 respectively, p>0.05). Subgroup analysis showed in progressing myopic group, IOP of children (<18 years old) declined with accommodation while IOP of adults (≥18 years) increased, and the difference was statistically significant (p = 0.008). However, after excluding the age factor, accommodation induced IOP changes of high progressing myopes (≤-6 D), low, moderate and non-myopes (>-6 D) was not significantly different after Bonferroni correction (p = 0.838). Conclusions Although no difference was detected between the baseline IOPs and accommodation induced IOP changes in progressing myopes, stable myopes and emmetropes, this study found accommodation could cause transient IOP elevation in adult progressing myopes. PMID:26517725

Progress in Piezo-Phototronic-Effect-Enhanced Light-Emitting Diodes and Pressure Imaging.

PubMed

Pan, Caofeng; Chen, Mengxiao; Yu, Ruomeng; Yang, Qing; Hu, Youfan; Zhang, Yan; Wang, Zhong Lin

2016-02-24

Wurtzite materials exhibit both semiconductor and piezoelectric properties under strains due to the non-central symmetric crystal structures. The three-way coupling of semiconductor properties, piezoelectric polarization and optical excitation in ZnO, GaN, CdS and other piezoelectric semiconductors leads to the emerging field of piezo-phototronics. This effect can efficiently manipulate the emission intensity of light-emitting diodes (LEDs) by utilizing the piezo-polarization charges created at the junction upon straining to modulate the energy band diagrams and the optoelectronic processes, such as generation, separation, recombination and/or transport of charge carriers. Starting from fundamental physics principles, recent progress in piezo-phototronic-effect-enhanced LEDs is reviewed; following their development from single-nanowire pressure-sensitive devices to high-resolution array matrices for pressure-distribution mapping applications. The piezo-phototronic effect provides a promising method to enhance the light emission of LEDs based on piezoelectric semiconductors through applying static strains, and may find perspective applications in various optoelectronic devices and integrated systems. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of high saturated free fatty acids feeding on progression of renal failure in rat model of experimental nephrotoxicity.

PubMed

Ibraheem, Zaid O; Sattar, Munavvar A; Abdullah, Nor A; Rathore, Hassaan A; Johns, Edward J

2012-02-01

The current study evaluates the impact of high saturated fat feeding in rat model of experimental nephrotoxicity induced by gentamicin. Sprague-Dawley rats weighing 200 g were randomized into four groups; the first one received the standard rodents chow for 8 weeks and was treated as control, the second group (HFD)received an experimental high fat diet rich in palm kernel oil (40% of Calories as fat) for the same period. The third group (HFDG) was given 80 mg/kg (body weight)/day gentamicin sulphate intraperitoneally during the last 24 days of the feeding period while the fourth group was given gentamicin as above along with the standard rodents chow. Renal function was assessed through measuring serum creatinine, creatinine clearance and absolute and fractional excretion of both sodium and potassium. At the end, rats underwent a surgical procedure for blood pressure measurement. Renal function study showed a stronger nephrotoxicity for HFDG group. Hypertension was observed in HFD group while the pressure declined after gentamicin co-administration. Overall, changing the feeding behavior toward using more SAFFAs for rats injected with gentamicin promotes the progression of renal failure.

Effect of high saturated free fatty acids feeding on progression of renal failure in rat model of experimental nephrotoxicity

PubMed Central

Ibraheem, Zaid O.; Sattar, Munavvar A.; Abdullah, Nor A.; Rathore, Hassaan A.; Johns, Edward J.

2012-01-01

The current study evaluates the impact of high saturated fat feeding in rat model of experimental nephrotoxicity induced by gentamicin. Sprague-Dawley rats weighing 200 g were randomized into four groups; the first one received the standard rodents chow for 8 weeks and was treated as control, the second group (HFD)received an experimental high fat diet rich in palm kernel oil (40% of Calories as fat) for the same period. The third group (HFDG) was given 80 mg/kg (body weight)/day gentamicin sulphate intraperitoneally during the last 24 days of the feeding period while the fourth group was given gentamicin as above along with the standard rodents chow. Renal function was assessed through measuring serum creatinine, creatinine clearance and absolute and fractional excretion of both sodium and potassium. At the end, rats underwent a surgical procedure for blood pressure measurement. Renal function study showed a stronger nephrotoxicity for HFDG group. Hypertension was observed in HFD group while the pressure declined after gentamicin co-administration. Overall, changing the feeding behavior toward using more SAFFAs for rats injected with gentamicin promotes the progression of renal failure. PMID:22364300

Focal cartilage defect compromises fluid-pressure dependent load support in the knee joint.

PubMed

Dabiri, Yaghoub; Li, LePing

2015-06-01

A focal cartilage defect involves tissue loss or rupture. Altered mechanics in the affected joint may play an essential role in the onset and progression of osteoarthritis. The objective of the present study was to determine the compromised load support in the human knee joint during defect progression from the cartilage surface to the cartilage-bone interface. Ten normal and defect cases were simulated with a previously tested 3D finite element model of the knee. The focal defects were considered in both condyles within high load-bearing regions. Fluid pressurization, anisotropic fibril-reinforcement, and depth-dependent mechanical properties were considered for the articular cartilages and menisci. The results showed that a small cartilage defect could cause 25% reduction in the load support of the knee joint due to a reduced capacity of fluid pressurization in the defect cartilage. A partial-thickness defect could cause a fluid pressure decrease or increase in the remaining underlying cartilage depending on the defect depth. A cartilage defect also increased the shear strain at the cartilage-bone interface, which was more significant with a full-thickness defect. The effect of cartilage defect on the fluid pressurization also depended on the defect sites and contact conditions. In conclusion, a focal cartilage defect causes a fluid-pressure dependent load reallocation and a compromised load support in the joint, which depend on the defect depth, site, and contact condition. Copyright © 2015 John Wiley & Sons, Ltd.

F-18 high alpha research vehicle surface pressures: Initial in-flight results and correlation with flow visualization and wind-tunnel data

NASA Technical Reports Server (NTRS)

Fisher, David F.; Banks, Daniel W.; Richwine, David M.

1990-01-01

Pressure distributions measured on the forebody and the leading-edge extensions (LEX's) of the NASA F-18 high alpha research vehicle (HARV) were reported at 10 and 50 degree angles of attack and at Mach 0.20 to 0.60. The results were correlated with HARV flow visualization and 6-percent scale F-18 wind-tunnel-model test results. The general trend in the data from the forebody was for the maximum suction pressure peaks to first appear at an angle of attack (alpha) of approximately 19 degrees and increase in magnitude with angle of attack. The LEX pressure distribution general trend was the inward progression and increase in magnitude of the maximum suction peaks up to vortex core breakdown and then the decrease and general flattening of the pressure distribution beyond that. No significant effect of Mach number was noted for the forebody results. However, a substantial compressibility effect on the LEX's resulted in a significant reduction in vortex-induced suction pressure as Mach number increased. The forebody primary and the LEX secondary vortex separation lines, from surface flow visualization, correlated well with the end of pressure recovery, leeward and windward, respectively, of maximum suction pressure peaks. The flight to wind-tunnel correlations were generally good with some exceptions.

Revisiting liver disease progression in HIV/HCV-coinfected patients: the influence of vitamin D, insulin resistance, immune status, IL28B and PNPLA3.

PubMed

Mandorfer, Mattias; Payer, Berit A; Schwabl, Philipp; Steiner, Sebastian; Ferlitsch, Arnulf; Aichelburg, Maximilian C; Stättermayer, Albert F; Ferenci, Peter; Obermayer-Pietsch, Barbara; Grabmeier-Pfistershammer, Katharina; Trauner, Michael; Peck-Radosavljevic, Markus; Reiberger, Thomas

2015-03-01

To perform a comprehensive study on independent modulators of liver fibrosis progression and determinants of portal pressure considering immune status, insulin resistance (IR), serum 25-hydroxyvitamin D (25(OH)D) levels, genetic variants of patatin-like phospholipase domain-containing protein 3 (PNPLA3) and interleukin 28B (IL28B) in a thoroughly documented cohort of HIV/hepatitis C-coinfected (HIV/HCV) patients. 25(OH)D deficiency (25(OH)DDEF), IR and low CD4(+) T-lymphocyte nadir (lowCD4NAD) were defined as 25(OH)D <20 ng × ml(-1) , HOMA-IR >2 and CD4nadir <200 cells × μl(-1) respectively. Liver fibrosis progression rate (FPR) was calculated as METAVIR F units divided by the number of years since HCV infection. Patients with a FPR > median FPR were assigned to the highFPR group. Among 86 HIV/HCV, the median FPR was 0.167 units × years(-1) . While the prevalence of prior alcohol abuse, lowCD4NAD and 25(OH)DDEF was higher among highFPR patients, the prevalence of IR was comparable. The association between 25(OH)DDEF and FPR was confirmed in a subgroup of patients with METAVIR stage F0/F1/F2 in which 25(OH)D levels are not affected by the severity of liver disease. The distribution of IL28B C/C and PNPLA3 non-C/C was similar, while PNPLA3 G/G was exclusively observed in highFPR patients. LowCD4NAD (OR: 2.95; 95% CI: 1.05-8.24; P = 0.039) and 25(OH)DDEF (OR: 5.62; 95% CI: 2.05-15.38; P = 0.001) were independently associated with highFPR and showed an additive effect. Portal pressure correlated with prior alcohol abuse, HCV-genotype 3, CD4(+) nadir and 25(OH)D levels. Two potentially modifiable factors, CD4(+) nadir and 25(OH)D levels, were both independent modulators of liver fibrosis progression and determinants of portal pressure. Further studies are warranted to assess the relevance of PNPLA3 for FPR in HIV/HCV. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Synthesis of Diamond-Like Carbon Films on Planar and Non-Planar Geometries by the Atmospheric Pressure Plasma Chemical Vapor Deposition Method

NASA Astrophysics Data System (ADS)

Noborisaka, Mayui; Hirako, Tomoaki; Shirakura, Akira; Watanabe, Toshiyuki; Morikawa, Masashi; Seki, Masaki; Suzuki, Tetsuya

2012-09-01

Diamond-like carbon (DLC) films were synthesized by the dielectric barrier discharge-based plasma deposition at atmospheric pressure and their hardness and gas barrier properties were measured. A decrease in size of grains and heating substrate temperature improved nano-hardness up to 3.3 GPa. The gas barrier properties of DLC-coated poly(ethylene terephthalate) (PET) sheets were obtained by 3-5 times of non-coated PET with approximately 0.5 µm in film thickness. The high-gas-barrier DLC films deposited on PET sheets are expected to wrap elevated bridge of the super express and prevent them from neutralization of concrete. We also deposited DLC films inside PET bottles by the microwave surface-wave plasma chemical vapor deposition (CVD) method at near-atmospheric pressure. Under atmospheric pressure, the films were coated uniformly inside the PET bottles, but did not show high gas barrier properties. In this paper, we summarize recent progress of DLC films synthesized at atmospheric pressure with the aimed of food packaging and concrete pillar.

Next Generation Life Support: High Performance EVA Glove

NASA Technical Reports Server (NTRS)

Walsh, Sarah K.

2015-01-01

The objectives of the High Performance EVA Glove task are to develop advanced EVA gloves for future human space exploration missions and generate corresponding standards by which progress may be quantitatively assessed. New technologies and manufacturing techniques will be incorporated into the new gloves to address finger and hand mobility, injury reduction and durability in nonpristine environments. Three prototypes will be developed, each focusing on different technological advances. A robotic assist glove will integrate a powered grasping system into the current EVA glove design to reduce astronaut hand fatigue and hand injuries. A mechanical counter pressure (MCP) glove will be developed to further explore the potential of MCP technology and assess its capability for countering the effects of vacuum or low pressure environments on the body by using compression fabrics or materials to apply the necessary pressure. A gas pressurized glove, incorporating new technologies, will be the most flight-like of the three prototypes. Advancements include the development and integration of aerogel insulation, damage sensing components, dust-repellant coatings, and dust tolerant bearings.

(DURIP 10) High Speed Intensified Imaging System For Studies Of Mixing And Combustion In Supersonic Flows And Hydrocarbon Flame Structure Measurements At Elevated Pressures

DTIC Science & Technology

2016-11-09

software, and their networking to augment optical diagnostics employed in supersonic reacting and non-reacting flow experiments . A high-speed...facility at Caltech. Experiments to date have made use of this equipment, extending previous capabilities to high-speed schlieren quantitative flow...visualization and image correlation velocimetry, with further experiments currently in progress. 15. SUBJECT TERMS 16. SECURITY CLASSIFICATION OF: 17

Arterial Pulse Pressure and Its Association With Reduced Stroke Volume During Progressive Central Hypovolemia

DTIC Science & Technology

2006-09-01

NM, Joyner MJ. Influence of increased central venous pressure on baroreflex control of sympathetic activity in humans. Am J Physiol Heart Circ Physiol...Arterial Pulse Pressure and Its Association With Reduced Stroke Volume During Progressive Central Hypovolemia Victor A. Convertino, PhD, William H...reduction of SV and change in MSNA during graded central hypovolemia in humans. Methods: After a 12-minute baseline data collection period, 13 men were

A numerical insight into elastomer normally closed micro valve actuation with cohesive interfacial cracking modelling

NASA Astrophysics Data System (ADS)

Wang, Dongyang; Ba, Dechun; Hao, Ming; Duan, Qihui; Liu, Kun; Mei, Qi

2018-05-01

Pneumatic NC (normally closed) valves are widely used in high density microfluidics systems. To improve actuation reliability, the actuation pressure needs to be reduced. In this work, we utilize 3D FEM (finite element method) modelling to get an insight into the valve actuation process numerically. Specifically, the progressive debonding process at the elastomer interface is simulated with CZM (cohesive zone model) method. To minimize the actuation pressure, the V-shape design has been investigated and compared with a normal straight design. The geometrical effects of valve shape has been elaborated, in terms of valve actuation pressure. Based on our simulated results, we formulate the main concerns for micro valve design and fabrication, which is significant for minimizing actuation pressures and ensuring reliable operation.

PBX 9502 Gas Generation Progress Report FY17

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

Holmes, Matthew David; Erickson, Michael Andrew Englert

The self-ignition (“cookoff”) behavior of PBX 9502 depends on the dynamic evolution of gas permeability and physical damage in the material. The time-resolved measurement of product gas generation yields insight regarding the crucial properties that dominate cookoff behavior. We report on small-scale laboratory testing performed in FY17, in which small unconfined samples of PBX 9502 were heated in a small custom-built sealed pressure vessel to self-ignition. We recorded time-lapse video of the evolving physical changes in the sample, quasi-static long-duration pressure rise, then high-speed video and dynamic pressure rise of the cookoff event. We report the full pressure attained duringmore » the cookoff of a 1.02g sample in a free volume of 62.5 cm 3.« less

Preparing and Training Professionals. Comparing Education to Six Other Fields

ERIC Educational Resources Information Center

Neville, Katherine S.; Sherman, Rachel H.; Cohen, Carol E.

2005-01-01

The federal No Child Left Behind Act requires schools, districts, and states to recruit and retain "highly qualified teachers" and to show annual progress toward the goal of 100 percent student proficiency in reading and mathematics by 2014. This heightened attention to teacher quality and pressure to improve achievement leaves educators facing a…

New Insights Into Pathophysiology, Diagnosis, and Treatment of Renovascular Hypertension.

PubMed

Samadian, Fariba; Dalili, Nooshin; Jamalian, Ali

2017-03-01

Renovascular disease includes renal artery stenosis, renovascular hypertension, and azotemic renovascular disease (ischemic nephropathy). Renovascular hypertension is defined as an elevated blood pressure caused by renal hypoperfusion, usually resulting from anatomic stenosis of the renal artery and activation of the renin-angiotensin system. It accounts for 1% to 2 % of all cases of hypertension in the general population and 5.8 % of secondary hypertension, but it plays a major role in treatable causes of hypertension in the young individuals. Although renovascular stenosis is a common and progressive disease in patients with atherosclerosis, it is a relatively uncommon cause of hypertension in patients with mild hypertension. In contrast, renal artery stenosis is more frequent in certain high-risk populations. Early diagnosis of renovascular hypertension and timely implementation of appropriate therapeutic procedures ensures optimum control of blood pressure, prevents ischemic nephropathy progression, and prevents the development of cardiovascular morbidity and mortality in the hypertensive patient population. As with most complex disorders, management decisions must be highly individualized for patients with renovascular disease. It is essential to consider renal arterial disease as one aspect of atherosclerotic disease.

Bonding Transition in SiO2 Glass at High Pressures: Applications to SiO2 Liquid in Earth's Interior

NASA Astrophysics Data System (ADS)

Yoo, C.; Lin, J.; Fukui, H.; Prendergast, D.; Okuchi, T.; Cai, Y.; Hiraoka, N.; Trave, A.; Eng, P.; Hu, M. Y.; Chow, P.

2006-12-01

SiO2 and MgSiO3 liquids are two major components in the magma deep inside the Earth. Knowledge of their electronic bonding characters at high pressures is essential to understanding the complex properties of the materials in the melts. The nature of pressure-induced bonding change in amorphous SiO2 has been an intriguing and long-standing problem that remains to be further understood. For example, previous infrared and X-ray diffraction studies suggested that a continuous transformation from the four- to six-fold coordinated silicon occurred in amorphous SiO2 at high pressures, whereas separate optical Raman studies attributed to a pressure-induced shift in the local ring statistics and a breakdown in the intermediate-range order. Here we have studied the oxygen near K-edge spectra of SiO2 glass to 51 GPa obtained using X-ray Raman scattering in a diamond-anvil cell, which directly probes the electronic bonding character of the sample. Our results provide conclusive evidence for a pressure-induced electronic bonding transition in SiO2 glass at high pressures. Although a progressive decrease in the mean Si-O-Si angle in the SiO4 tetrahedra is believed to be responsible for the irreversible densification in SiO2 glass at high pressures, our observed transition is reversible upon decompression. A similar transformation is also expected to occur in silicate glasses and melts, which will most definitely alter their physical, mechanical and transport properties in the magma chamber deep in the Earth's interior. This work was performed under the auspices of the U.S. DOE by UC/LLNL under Contract W-7405-Eng-48.

Myocardial infarction increases progressive visual field defects in well treated early primary open angle glaucoma--a prospective case control study.

PubMed

Mondal, Lakshmikanta; Baidya, Krishnapada; Choudhury, Himadri; Roy, Rupam

2013-06-01

The purpose of the study was to evaluate the progression of glaucomatous field damage in patients with stable primary open angle glaucoma after an attack of myocardial infarction. In this case control study, 62 open angle glaucoma patients were selected and regularly followed up. Among 62 patients, 9 had an attack of myocardial infarction. The intra-ocular pressure and visual field progression of both the groups (myocardial infarction versus no myocardial infarction) were analysed. Three (33.3%) out of 9 patients who had suffered from myocardial infarction showed progressive visual field loss whereas only 9 (16.9%) out of 53 patients who did not suffer from myocardial infarction, showed progressive field changes. Both the groups had stable target intra-ocular pressure between 14 and 16 mm Hg. Myocardial infarction may adversely influence the progression of primary open angle glaucoma which is suspected to result from ischaemia induced neuronal loss and only control of intraocular pressure is not the only solution. We have to look for other drugs that prevents ischaemia induced neuronal damage.

Preemptive mechanical ventilation can block progressive acute lung injury.

PubMed

Sadowitz, Benjamin; Jain, Sumeet; Kollisch-Singule, Michaela; Satalin, Joshua; Andrews, Penny; Habashi, Nader; Gatto, Louis A; Nieman, Gary

2016-02-04

Mortality from acute respiratory distress syndrome (ARDS) remains unacceptable, approaching 45% in certain high-risk patient populations. Treating fulminant ARDS is currently relegated to supportive care measures only. Thus, the best treatment for ARDS may lie with preventing this syndrome from ever occurring. Clinical studies were examined to determine why ARDS has remained resistant to treatment over the past several decades. In addition, both basic science and clinical studies were examined to determine the impact that early, protective mechanical ventilation may have on preventing the development of ARDS in at-risk patients. Fulminant ARDS is highly resistant to both pharmacologic treatment and methods of mechanical ventilation. However, ARDS is a progressive disease with an early treatment window that can be exploited. In particular, protective mechanical ventilation initiated before the onset of lung injury can prevent the progression to ARDS. Airway pressure release ventilation (APRV) is a novel mechanical ventilation strategy for delivering a protective breath that has been shown to block progressive acute lung injury (ALI) and prevent ALI from progressing to ARDS. ARDS mortality currently remains as high as 45% in some studies. As ARDS is a progressive disease, the key to treatment lies with preventing the disease from ever occurring while it remains subclinical. Early protective mechanical ventilation with APRV appears to offer substantial benefit in this regard and may be the prophylactic treatment of choice for preventing ARDS.

Preemptive mechanical ventilation can block progressive acute lung injury

PubMed Central

Sadowitz, Benjamin; Jain, Sumeet; Kollisch-Singule, Michaela; Satalin, Joshua; Andrews, Penny; Habashi, Nader; Gatto, Louis A; Nieman, Gary

2016-01-01

Mortality from acute respiratory distress syndrome (ARDS) remains unacceptable, approaching 45% in certain high-risk patient populations. Treating fulminant ARDS is currently relegated to supportive care measures only. Thus, the best treatment for ARDS may lie with preventing this syndrome from ever occurring. Clinical studies were examined to determine why ARDS has remained resistant to treatment over the past several decades. In addition, both basic science and clinical studies were examined to determine the impact that early, protective mechanical ventilation may have on preventing the development of ARDS in at-risk patients. Fulminant ARDS is highly resistant to both pharmacologic treatment and methods of mechanical ventilation. However, ARDS is a progressive disease with an early treatment window that can be exploited. In particular, protective mechanical ventilation initiated before the onset of lung injury can prevent the progression to ARDS. Airway pressure release ventilation (APRV) is a novel mechanical ventilation strategy for delivering a protective breath that has been shown to block progressive acute lung injury (ALI) and prevent ALI from progressing to ARDS. ARDS mortality currently remains as high as 45% in some studies. As ARDS is a progressive disease, the key to treatment lies with preventing the disease from ever occurring while it remains subclinical. Early protective mechanical ventilation with APRV appears to offer substantial benefit in this regard and may be the prophylactic treatment of choice for preventing ARDS. PMID:26855896

High altitude simulation, substance P and airway rapidly adapting receptor activity in rabbits.

PubMed

Bhagat, R; Yasir, A; Vashisht, A; Kulshreshtha, R; Singh, S B; Ravi, K

2011-09-15

To investigate whether there is a change in airway rapidly adapting receptor (RAR) activity during high altitude exposure, rabbits were placed in a high altitude simulation chamber (barometric pressure, 429 mm Hg). With 12 h exposure, when there was pulmonary congestion, an increase in basal RAR activity was observed. With 36 h exposure, when there was alveolar edema, there was a further increase in basal RAR activity. In these backgrounds, there was an increase in the sensitivity of the RARs to substance P (SP). To assess whether there was an increase in lung SP level, neutral endopeptidase activity was determined which showed a decrease in low barometric pressure exposed groups. It is concluded that along with the SP released, pulmonary congestion and edema produced, respectively by different durations of low barometric pressure exposure cause a progressive increase in RAR activity which may account for the respiratory symptoms reported in climbers who are unacclimatized. Copyright © 2011 Elsevier B.V. All rights reserved.

The dielectric signature of glass density

NASA Astrophysics Data System (ADS)

Rams-Baron, M.; Wojnarowska, Z.; Knapik-Kowalczuk, J.; Jurkiewicz, K.; Burian, A.; Wojtyniak, M.; Pionteck, J.; Jaworska, M.; Rodríguez-Tinoco, C.; Paluch, M.

2017-09-01

At present, we are witnessing a renewed interest in the properties of densified glasses prepared by isobaric cooling of a liquid at elevated pressure. As high-pressure densification emerges as a promising approach in the development of glasses with customized features, understanding and controlling their unique properties represent a contemporary scientific and technological goal. The results presented herein indicate that the applied high-pressure preparation route leads to a glassy state with higher density (˜1%) and a reduced free volume of about 7%. We show that these subtle structural changes remarkably influence the dielectric response and spectral features of β-relaxation in etoricoxib glass. Our study, combining dynamical and structural techniques, reveal that β-relaxation in etoricoxib is extremely sensitive to the variations in molecular packing and can be used to probe the changes in glass density. Such connection is technologically relevant and may advance further progress in the field.

Spectral signatures for RDX-based explosives in the 3 micron region

NASA Astrophysics Data System (ADS)

Osborn, Tabetha; Kaimal, Sindhu; Reeve, Scott W.; Burns, William

2008-04-01

Explosive compounds such as RDX, and HMX present significant challenges to optically based sensors. This difficulty is due in part to the low vapor pressures these compounds possess. One approach for sensing explosives that circumvents the low explosive vapor pressure problem, involves focusing on the trace amounts of relatively high vapor pressure impurities that will be present in the vapor signature. In order to effectively detect these volatile impurities, the spectral signature databases must be readily available. One of our goals therefore, is the generation of a database of high resolution spectral signatures for these volatile organic impurities. Some rather formidable spectroscopic measurement challenges have been encountered while working to extend the spectral signature effort to the 3 micron region. Here we will outline progress to date, with a focus on the volatile organic compounds formaldehyde, acetaldehyde, nitromethane, acetone, isobutene, and cyclohexanone.

Realizing Steady State Tokamak Operation for Fusion Energy

NASA Astrophysics Data System (ADS)

Luce, T. C.

2009-11-01

Continuous operation of a tokamak for fusion energy has obvious engineering advantages, but also presents physics challenges beyond the achievement of conditions needed for a burning plasma. The power from fusion reactions and external sources must support both the pressure and the current equilibrium without inductive current drive, leading to demands on stability, confinement, current drive, and plasma-wall interactions that exceed those for pulsed tokamaks. These conditions have been met individually in the present generation of tokamaks, and significant progress has been made in the last decade to realize scenarios where the required conditions are obtained simultaneously. Tokamaks are now operated routinely without disruptions close to the ideal MHD pressure limit, as needed for steady-state operation. Scenarios that project to high fusion gain have been demonstrated where more than half of the current is supplied by the ``bootstrap'' current generated by the pressure gradient in the plasma. Fully noninductive sustainment has been obtained for about a resistive time (the longest intrinsic time scale in the confined plasma) with normalized pressure and confinement approaching those needed for demonstration of steady-state conditions in ITER. One key challenge remaining to be addressed is how to handle the demanding heat and particle fluxes expected in a steady-state tokamak without compromising the high level of core plasma performance. Rather than attempt a comprehensive historical survey, this review will start from the plasma requirements of a steady-state tokamak powerplant, illustrate with examples the progress made in both experimental and theoretical understanding, and point to the remaining physics challenges.

Effect of blood pressure lowering on markers of kidney disease progression.

PubMed

Udani, Suneel M; Koyner, Jay L

2009-10-01

Hypertension remains a common comorbidity and cause of chronic kidney disease (CKD). As the number of patients with CKD grows, so does the need to identify modifiable risk factors for CKD progression. Data on slowing progression of CKD or preventing end-stage renal disease with aggressive blood pressure control have not yielded definitive conclusions regarding ideal blood pressure targets. Shifting the focus of antihypertensive therapy to alternative markers of end-organ damage, specifically proteinuria, has yielded some promise in preventing the progression of CKD. Nevertheless, proteinuria and decline in estimated GFR may represent an irreversible degree of injury to the kidney that limits the impact of any therapy. The identification and use of novel markers of kidney injury to assess the impact of antihyper-tensive therapy may yield clearer direction with regard to optimal management of hypertension in the setting of CKD.

Short communication: Effects of high-pressure processing on the inactivity of Cronobacter sakazakii in whole milk and skim milk samples.

PubMed

Jiao, Rui; Gao, Jina; Li, Yinxiang; Zhang, Xiyan; Zhang, Maofeng; Ye, Yingwang; Wu, Qingping; Fan, Hongying

2016-10-01

Powdered infant formula is considered as the main transmission vehicle for Cronobacter sakazakii infections including meningitis, septicemia, and necrotizing enterocolitis. The effects of high-pressure processing treatment on inactivation of C. sakazakii ranging from 100 to 400 MPa for 3.0, 5.0, and 7.0 min in whole milk and skim milk were studied. Significant differences in inactivation of C. sakazakii were observed in milk samples under different pressures for 3 to 7 min compared with untreated samples, and C. sakazakii was not detected after 400 MPa for 3 min. The lethality rates of C. sakazakii cells in whole and skim milk with an initial level of 10(4) cfu/mL after 100 and 200 MPa treatments were not significantly different, but relatively higher lethality rates were found in whole milk after 300 MPa treatment than in skim milk. Finally, the scanning electron micrographs indicated that cellular envelope and intracellular damage of C. sakazakii cells were apparent after 300 and 400 MPa for 5.0 min compared with the untreated cells, and a progressive increase of injured cells with increased pressure treatment was found. It was concluded that C. sakazakii was sensitive to high-pressure processing treatment and that high-pressure processing treatment with 400 MPa for 3.0 min can be used to control C. sakazakii contamination in milk samples. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Design and fabrication of a high temperature leading edge heating array, phase 1

NASA Technical Reports Server (NTRS)

1972-01-01

Progress during a Phase 1 program to design a high temperature heating array is reported for environmentally testing full-scale shuttle leading edges (30 inch span, 6 to 15 inch radius) at flight heating rates and pressures. Heat transfer analyses of the heating array, individual modules, and the shuttle leading edge were performed, which influenced the array design, and the design, fabrication, and testing of a prototype heater module.

Progress in the Production of JP-8 Based Hydrogen and Advanced Tactical Fuels for Military Applications

DTIC Science & Technology

2011-02-01

of a multi- year program to develop, optimize, and demonstrate the military viability of a technology for on-demand production of high...continuous reactor system used for kinetic rate data experiment 86 52 Schematic of a differential reactor. The catalyst bed is kept small , and...program to develop, optimize, and demonstrate the military viability of a technology for on-demand production of high-pressure hydrogen for fuel

Systolic hypertension and progression of aortic valve calcification in patients with aortic stenosis: results from the PROGRESSA study.

PubMed

Tastet, Lionel; Capoulade, Romain; Clavel, Marie-Annick; Larose, Éric; Shen, Mylène; Dahou, Abdellaziz; Arsenault, Marie; Mathieu, Patrick; Bédard, Élisabeth; Dumesnil, Jean G; Tremblay, Alexe; Bossé, Yohan; Després, Jean-Pierre; Pibarot, Philippe

2017-01-01

Hypertension is highly prevalent in patients with aortic stenosis (AS) and is associated with worse outcomes. The current prospective study assessed the impact of systolic hypertension (SHPT) on the progression of aortic valve calcification (AVC) measured by multidetector computed tomography (MDCT) in patients with AS. The present analysis includes the first series of 101 patients with AS prospectively recruited in the PROGRESSA study. Patients underwent comprehensive Doppler echocardiography and MDCT exams at baseline and after 2-year follow-up. AVC and coronary artery calcification (CAC) were measured using the Agatston method. Patients with SHPT at baseline (i.e. systolic blood pressure ≥140 mmHg; n = 37, 37%) had faster 2-year AVC progression compared with those without SHPT (i.e. systolic blood pressure <140 mmHg) (AVC median [25th percentile-75th percentile]: +370 [126-824] vs. +157 [58-303] AU; P = 0.007, respectively). Similar results were obtained with the analysis of AVC progression divided by the cross-sectional area of the aortic annulus (AVC density : +96 [34-218] vs. +45 [14-82] AU/cm 2 , P = 0.01, respectively). In multivariable analysis, SHPT remained significantly associated with faster progression of AVC or AVC density (all P = 0.001). There was no significant difference between groups with respect to progression of CAC (+39 [3-199] vs. +41 [0-156] AU, P = 0.88). This prospective study shows for the first time that SHPT is associated with faster AVC progression but not with CAC progression in AS patients. These findings provide further support for the elaboration of randomized clinical trials to assess the efficacy of antihypertensive medication to slow the stenosis progression in patients with AS. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2016. For permissions please email: journals.permissions@oup.com.

Study of photosensitization reaction progress in a 96 well plate with photosensitizer rich condition using Talaporfin sodium

NASA Astrophysics Data System (ADS)

Ogawa, Emiyu; Takahashi, Mei; Arai, Tsunenori

2013-02-01

To quantitatively investigate photosensitization reaction in vitro against myocardial cells with photosensitizer rich condition in solution using Talaporfin sodium in the well of a 96 well plate, we studied photosensitization reaction progress in this well. We have proposed non-thermal conduction block of myocardium tissue using the photosensitization reaction with laser irradiation shortly after Talaporfin sodium injection. In above situation, the photosensitizer is located outside the myocardial cells in high concentration. To understand interaction of the photosensitization reaction in which the photosensitizer distributes outside cells, the photosensitization reaction progress in the well was studied. Talaporfin sodium (799.69 MW) solution and a 663 nm diode laser were used. The photosensitizer solution concentrations of 12.5-37.5 μM were employed. The photosensitizer fluorescence with 0.29 W/cm2 in irradiance, which was optimized in previous cell death study, was measured during the laser irradiation until 40 J/cm2. The photosensitizer solution absorbance and dissolved oxygen pressure after the laser irradiation were also measured. We found that the photosensitization reaction progress had 2 distinctive phases of different reaction rate: rapid photosensitization reaction consuming dissolved oxygen and gentle photosensitization reaction with oxygen diffusion from the solution-air boundary. The dissolved oxygen pressure and photosensitizer solution absorbance were 30% and 80% of the initial values after the laser irradiation, respectively. Therefore, oxygen was rate-controlling factor of the photosensitization reaction in the well with the photosensitizer rich condition. In the oxygen diffusion phase, the oxygen pressure was maintained around 40 mmHg until the laser irradiation of 40 J/cm2 and it is similar to that of myocardium tissue in vivo. We think that our 96 well plate in vitro system may simulate PDT in myocardial tissue with photosensitization reaction parameters mentioned above.

Relationship between exercise pressure gradient and haemodynamic progression of aortic stenosis.

PubMed

Ringle, Anne; Levy, Franck; Ennezat, Pierre-Vladimir; Le Goffic, Caroline; Castel, Anne-Laure; Delelis, François; Menet, Aymeric; Malaquin, Dorothée; Graux, Pierre; Vincentelli, André; Tribouilloy, Christophe; Maréchaux, Sylvestre

We hypothesized that large exercise-induced increases in aortic mean pressure gradient can predict haemodynamic progression during follow-up in asymptomatic patients with aortic stenosis. We retrospectively identified patients with asymptomatic moderate or severe aortic stenosis (aortic valve area<1.5cm 2 or<1cm 2 ) and normal ejection fraction, who underwent an exercise stress echocardiography at baseline with a normal exercise test and a resting echocardiography during follow-up. The relationship between exercise-induced increase in aortic mean pressure gradient and annualised changes in resting mean pressure gradient during follow-up was investigated. Fifty-five patients (mean age 66±15 years; 45% severe aortic stenosis) were included. Aortic mean pressure gradient significantly increased from rest to peak exercise (P<0.001). During a median follow-up of 1.6 [1.1-3.2] years, resting mean pressure gradient increased from 35±13mmHg to 48±16mmHg, P<0.0001. Median annualised change in resting mean pressure gradient during follow-up was 5 [2-11] mmHg. Exercise-induced increase in aortic mean pressure gradient did correlate with annualised changes in mean pressure gradient during follow-up (r=0.35, P=0.01). Hemodynamic progression of aortic stenosis was faster in patients with large exercise-induced increase in aortic mean pressure gradient (≥20mmHg) as compared to those with exercise-induced increase in aortic mean pressure gradient<20mmHg (median annualised increase in mean pressure gradient 19 [6-28] vs. 4 [2-10] mmHg/y respectively, P=0.002). Similar results were found in the subgroup of 30 patients with moderate aortic stenosis. Large exercise-induced increases in aortic mean pressure gradient correlate with haemodynamic progression of stenosis during follow-up in patients with asymptomatic aortic stenosis. Further studies are needed to fully establish the role of ESE in the decision-making process in comparison to other prognostic markers in asymptomatic patients with aortic stenosis. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

High hydrostatic pressure processing affects the phenolic profile, preserves sensory attributes and ensures microbial quality of jabuticaba (Myrciaria jaboticaba) juice.

PubMed

Inada, Kim Op; Torres, Alexandre G; Perrone, Daniel; Monteiro, Mariana

2018-01-01

Jabuticaba (Myrciaria jaboticaba) is a Brazilian fruit rich in phenolic compounds and much appreciated for its sweet and slightly tangy taste. However, the high perishability of this fruit impairs its economic exploitation, creating an opportunity for the development of innovative products, such as high hydrostatic pressure (HHP) processed juices. We investigated the effect of HHP (200, 350 and 500 MPa for 5, 7.5 and 10 min) on phenolic compounds, antioxidant activity and microbiological quality of jabuticaba juice and the effect of the most effective HHP condition on its sensory acceptance. Pressurization increased total phenolic compound content (up to 38%) and antioxidant activity by FRAP assay (up to 46%), probably by increasing phenolic compound extractability due to tissue damage. Pressurization progressively decreased microbial counts, and colony growth was undetectable at pressures of 350 MPa or 500 MPa. With the exception of aroma, which was 10% lower in pressurized juice at 350 MPa for 7.5 min in relation to unprocessed juice, HHP did not affect sensory acceptance scores. Our results show that HHP was effective in ensuring microbiological quality, increasing bioactive potential and maintaining overall acceptance of jabuticaba juice, reinforcing the potential application of this processing technology in bioactive-rich foods. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Making Sense of Higher Education: Students as Consumers and the Value of the University Experience

ERIC Educational Resources Information Center

Woodall, Tony; Hiller, Alex; Resnick, Sheilagh

2014-01-01

In the global university sector competitive funding models are progressively becoming the norm, and institutions/courses are frequently now subject to the same kind of consumerist pressures typical of a highly marketised environment. In the United Kingdom, for example, students are increasingly demonstrating customer-like behaviour and are now…

Teachers' Perceptions of High School Principal's Monitoring of Student Progress and the Relationship to Student Achievement

ERIC Educational Resources Information Center

Chappelear, T. C.; Price, Ted

2012-01-01

Principals in school buildings are under immense pressure to improve outcomes for all students. Recent literature suggests this accountability may be at least partly warranted, as there is overwhelming evidence that building principals can positively impact student achievement through their behavior as effective instructional leaders. Much of the…

Subacute Oxidative Stress and Glial Reactivity in the Amygdala are Associated with Increased Anxiety Following Blast Neurotrauma.

PubMed

Sajja, Venkata Siva Sai Sujith; Hubbard, William B; VandeVord, Pamela J

2015-08-01

Behavioral symptoms, such as anxiety, are widely reported after blast overpressure (BOP) exposure. Amygdalar vulnerability to increasing magnitudes of BOP has not been investigated, and single exposures to blast have been limited to acute (<72 h) assessment. Rats were exposed to a single low, moderate, or high BOP (10, 14, or 24 psi) with an advanced blast simulator to test the susceptibility of the amygdala. Anxiety-like behavior was observed in the low- and moderate-pressure groups when subjected to the light/dark box assessment 7 days after the blast but not in high-pressure group. Immunohistochemistry was performed to measure apoptosis (cleaved caspase-3), neuronal loss (NeuN), reactive astrocytes (glial fibrillary acidic protein), microglia (Iba-1), and oxidative stress (CuZn superoxide dismutase). Slower progression of injury cascades was associated with a significant increase in anxiety, apoptosis, and astrogliosis in the low pressure group compared with others. A significant increase of CuZn superoxide dismutase in the low pressure group could be associated with neuroprotection from cell death caused by oxidative stress because neuronal loss was significant in the moderate- and high- but not the low-pressure group. Overall, this study demonstrated that overpressure as low as 10 psi can induce subacute anxiety, in addition to neuropathologic changes in the amygdala.

Resource footprints and their ecosystem consequences

PubMed Central

Verones, Francesca; Moran, Daniel; Stadler, Konstantin; Kanemoto, Keiichiro; Wood, Richard

2017-01-01

A meaningful environmental impact analysis should go beyond the accounting of pressures from resource use and actually assess how resource demand affects ecosystems. The various currently available footprints of nations report the environmental pressures e.g. water use or pollutant emissions, driven by consumption. However, there have been limited attempts to assess the environmental consequences of these pressures. Ultimately, consequences, not pressures, should guide environmental policymaking. The newly released LC-Impact method demonstrates progress on the path to providing this missing link. Here we present “ecosystem impact footprints” in terms of the consequences for biodiversity and assess the differences in impact footprint results from MRIO-based pressure footprints. The new perspective reveals major changes in the relative contribution of nations to global footprints. Wealthy countries have high pressure footprints in lower-income countries but their impact footprints often have their origin in higher-income countries. This shift in perspective provides a different insight on where to focus policy responses to preserve biodiversity. PMID:28112168

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

PubMed

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

2016-05-01

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

Thermoelasticity and anomalies in the pressure dependence of phonon velocities in niobium

NASA Astrophysics Data System (ADS)

Zou, Yongtao; Li, Ying; Chen, Haiyan; Welch, David; Zhao, Yusheng; Li, Baosheng

2018-01-01

Compressional and shear wave velocities of polycrystalline niobium have been measured at simultaneously high pressures and temperatures up to 5.8 GPa and 1073 K, respectively, using ultrasonic interferometry in conjunction with synchrotron x-ray techniques. An anomalous pressure-induced softening behavior in the phonon velocities, probably owing to the topological change in the Fermi surface, has been observed at ˜4.8 GPa during cold compression, which is supported by the elasticity data from our first-principles calculations. In contrast, both the bulk (BS) and shear (G) moduli increase with pressures but decrease with temperatures upon compression at extreme P-T up to 5.8 GPa and 1073 K. Using finite strain equation-of-state approaches, the elasticity of bulk and shear moduli and their pressure and temperature dependences are derived from the directly measured velocities and densities, yielding BS0 = 174.9(3.2) GPa, G0 = 37.1(3) GPa, ∂BS/∂P = 3.97(9), ∂G/∂P = 0.83(5), ∂BS/∂T = -0.064(7) GPa/K, and ∂G/∂T = -0.012(3) GPa/K. On the basis of the current thermoelasticity data, Debye temperature and the high-pressure melting curve of Nb are derived. The origin of the anomalies in shear behavior at high pressure might be attributed to the progressive s-d electron-transfer-induced topological changes of the Fermi surface upon compression.

Plant adaptation to low atmospheric pressures: potential molecular responses

NASA Technical Reports Server (NTRS)

Ferl, Robert J.; Schuerger, Andrew C.; Paul, Anna-Lisa; Gurley, William B.; Corey, Kenneth; Bucklin, Ray

2002-01-01

There is an increasing realization that it may be impossible to attain Earth normal atmospheric pressures in orbital, lunar, or Martian greenhouses, simply because the construction materials do not exist to meet the extraordinary constraints imposed by balancing high engineering requirements against high lift costs. This equation essentially dictates that NASA have in place the capability to grow plants at reduced atmospheric pressure. Yet current understanding of plant growth at low pressures is limited to just a few experiments and relatively rudimentary assessments of plant vigor and growth. The tools now exist, however, to make rapid progress toward understanding the fundamental nature of plant responses and adaptations to low pressures, and to develop strategies for mitigating detrimental effects by engineering the growth conditions or by engineering the plants themselves. The genomes of rice and the model plant Arabidopsis thaliana have recently been sequenced in their entirety, and public sector and commercial DNA chips are becoming available such that thousands of genes can be assayed at once. A fundamental understanding of plant responses and adaptation to low pressures can now be approached and translated into procedures and engineering considerations to enhance plant growth at low atmospheric pressures. In anticipation of such studies, we present here the background arguments supporting these contentions, as well as informed speculation about the kinds of molecular physiological responses that might be expected of plants in low-pressure environments.

Carotid Baroreflex Function During Prolonged Exercise

NASA Technical Reports Server (NTRS)

Raven, P. B.

1999-01-01

Astronauts are often required to work (exercise) at moderate to high intensities for extended periods while performing extra-vehicular activities (EVA). Although the physiologic responses associated with prolonged exercise have been documented, the mechanisms involved in blood pressure regulation under these conditions have not yet been fully elucidated. An understanding of this issue is pertinent to the ability of humans to perform work in microgravity and complies with the emphasis of NASA's Space Physiology and Countermeasures Program. Prolonged exercise at a constant workload is know to result in a progressive decrease in mean arterial pressure (MAP) concomitant with a decrease in stroke volume and a compensatory increase in heart rate. The continuous decrease in MAP during the exercise, which is related to the thermoregulatory redistribution of circulating blood volume to the cutaneous circulation, raises the question as to whether there is a loss of baroreflex regulation of arterial blood pressure. We propose that with prolongation of the exercise to 60 minutes, progressive increases on central command reflect a progressive upward resetting of the carotid baroreflex (CBR) such that the operating point of the CBR is shifted to a pressure below the threshold of the reflex rendering it ineffectual in correcting the downward drift in MAP. In order to test this hypothesis, experiments have been designed to uncouple the global hemodynamic response to prolonged exercise from the central command mediated response via: (1) continuous maintenance of cardiac filling volume by intravenous infusion of a dextran solution; and (2) whole body surface cooling to counteract thermoregulatory cutaneous vasodialation. As the type of work (exercise) performed by astronauts is inherently arm and upper body dependent, we will also examine the physiologic responses to prolonged leg cycling and arm ergometry exercise in the supine positions with and without level lower body negative pressure (-10 torr) to mimic spaceflight- related decreases in cardiac filling volumes.

High-resolution spectroscopy of jet-cooled CH5+: Progress

NASA Astrophysics Data System (ADS)

Savage, C.; Dong, F.; Nesbitt, D. J.

2015-01-01

Protonated methane (CH5+) is thought to be a highly abundant molecular ion in interstellar medium, as well as a potentially bright μwave- mm wave emitter that could serve as a tracer for methane. This paper describes progress and first successful efforts to obtain a high resolution, supersonically cooled spectrum of CH5+ in the 2900-3100 cm-1 region, formed in a slit supersonic discharge at low jet temperatures and with sub-Doppler resolution. Short term precision in frequency measurement (< 5 MHz on an hour time scale) is obtained from a thermally controlled optical transfer cavity servoloop locked onto a frequency stabilized HeNe laser. Long term precision (< 20 MHz day-to-day) due to pressure, temperature and humidity dependent index of refraction effects in the optical transfer cavity is also present and discussed.

Structure and dynamics in low-dimensional guest host solids

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

Fischer, J.

1991-04-01

This progress report presents results from work during the period of June 1, 1990 through May 31st, 1991. Topics discussed include instrumentation, publications, and personnel. Work areas discussed include: pressure-induced transitions in Li- and Ag-TiS{sub 2}, hyper-dense superconducting GIC's, temperature-dependent x-ray structure of (CH){sub x} and (CH){sub 2{sup x}}:analogies to rotator phases in short-chain alkanes, trans-(CH){sub x} at high'' pressure, broken symmetries'' in polymer intercalation channel lattices, high-resolution study of conductivity and cell potential vs. concentration in K-doped (CH){sub x}, new'' doped (CH){sub x} phases: ternary compounds and amorphous'' intercalation compounds, and vibrational density states from inelastic neutron scattering. (JF).

Semiclassical Planetology: a progress report

NASA Astrophysics Data System (ADS)

Celebonovic, V.

1999-12-01

Work on planetary internal structure has started in Yugoslavia in the early sixties.It was initiated by P.Savic and R.Kasanin,who have jointly developed a theory of the behaviour of materials under high pressure.By its physical basis,this theory is semiclassical,because it is based on classical physics combined with some quantum mechanical results.The calculations in the theory ( both laboratory and planetological) are baed on ths idea that high pressure leads to excitation and ionisation of atoms and/or molecules which make up the specimen. In this paper we shall briefly present the main ideas of this theory,and then discuss its planetological applications. References P.Savic and V.Celebonovic: 1994,AIP Conf.Proc.,vol.309,p.53. V.Celebonovic: 1999,preprint cond-mat/9906027

Progress in the utilization of an oxide-dispersion-strengthened alloy for small engine turbine blades

NASA Technical Reports Server (NTRS)

Beatty, T. G.; Millan, P. P.

1984-01-01

The conventional means of improving gas turbine engine performance typically involves increasing the turbine inlet temperature; however, at these higher operational temperatures the high pressure turbine blades require air-cooling to maintain durability. Air-cooling imposes design, material, and economic constraints not only on the turbine blades but also on engine performance. The use of uncooled turbine blades at increased operating temperatures can offer significantly improved performance in small gas turbine engines. A program to demonstrate uncooled MA6000 high pressure turbine blades in a GTEC TFE731 turbofan engine is being conducted. The project goals include demonstration of the advantages of using uncooled MA6000 turbine blades as compared with cast directionally solidified MAR-M 247 blades.

[Stress management in the treatment of essential arterial hypertension].

PubMed

Schwickert, M; Langhorst, J; Paul, A; Michalsen, A; Dobos, G J

2006-11-23

Between 60 and 90% of patients consult their family doctor for stress-associated complaints. Not infrequently, a considerable number of these patients already have elevated blood pressure. The positive effect on high blood pressure of relaxation techniques has been confirmed in various studies. Accordingly, stress management should now have a permanent place in effective antihypertensive treatment. Appropriate relaxation techniques include, for example, autogenic training, progressive muscle relaxation, visualization and breathing exercises, chi gong and yoga. These practices are incorporated in various lifestyle programs. They act in different ways, and can be offered to the patient in accordance with his/her individual wishes.

Low Blood Pressure (Hypotension)

MedlinePlus

... Low blood pressure on standing up (orthostatic, or postural, hypotension). This is a sudden drop in blood ... progressive damage to the autonomic nervous system, which controls involuntary functions such as blood pressure, heart rate, ...

The Inverse Relationship between Cardiorespiratory Fitness and Intima-Media Thickness with Prehypertensive Middle-Aged Women.

PubMed

Kim, Dokyung; Park, Wonhah

2017-12-01

Individuals with prehypertension have a greater risk of developing hypertension and cardiovascular disease than those with normal blood pressure. Good cardiorespiratory fitness has been associated with a reduced risk for cardiovascular diseases, but whether it is related to slower progression of early atherosclerosis is unclear. We evaluated 442 women, aged 40-60 years, with resting systolic blood pressure 120-139 mmHg and diastolic blood pressure 80-89 mmHg, defined as prehypertension in cross-sectional study. Blood glucose, blood lipids and carotid intima-media thickness (CIMT) were measured at rest. Cardiorespiratory fitness (VO 2 peak) was measured by respiratory gas exchange during a treadmill exercise test. Participants were divided into three cardiorespiratory fitness levels: low, moderate, and high. The prevalence of subclinical carotid atherosclerosis was defined as a mean carotid intima-media thickness greater than the 75 th percentile. After adjustment for various confounders, a high cardiorespiratory fitness level was associated with significantly lower SBP, DBP and CIMT compared with low and moderate fitness (p < 0.05). After adjustment for established risk factors, high and moderate fitness were each associated with significantly lower odds ratios for carotid atherosclerosis 0.74 (95% CI 0.45-0.92) and 0.70 (95% CI 0.46-0.95), respectively, compared with low fitness. Our results indicate that good cardiorespiratory fitness is associated with a slower progression of early atherosclerosis in middle-aged women. These findings are important, because they emphasize that middle-aged women can be evaluated for cardiorespiratory fitness to estimate their future risk for atherosclerotic vascular diseases.

Eclogites and their geodynamic interpretation: a history

NASA Astrophysics Data System (ADS)

Godard, Gaston

2001-09-01

Haüy coined the term eclogite, meaning "chosen rock", in 1822, but de Saussure had already observed rocks of this type in the Alps four decades earlier. Throughout the 19th century, the origin of eclogite remained an enigma, in spite of great progress in our knowledge of this rock. The first chemical analyses, carried out around 1870, showed that its bulk composition was the same as gabbro. Therefore, eclogite was thought to be either an igneous rock of gabbroic composition or a metamorphosed gabbro. This second hypothesis became preferred when progressive transitions were observed between gabbros and eclogites. In 1903, simply by comparing the molar volumes of gabbroic and eclogite parageneses, Becke inferred that eclogite was the high-pressure equivalent of gabbro. In 1920, eclogite was involved in the conception of the metamorphic facies by Eskola. However, a few researchers denied the existence of an eclogite facies, and claimed that high stress instead of high lithostatic pressure could generate eclogites. In the 1960s, consideration of the water pressure parameter also favoured the belief that eclogite was simply the anhydrous equivalent of amphibolite. Finally, eclogite was definitely considered as a high-pressure metamorphic rock following the development of experimental petrology and the application of thermodynamics. In recent years, the discovery of ultrahigh-pressure coesite-bearing rocks in the crust has drastically changed geologists' ideas concerning the limits of eclogite-facies crustal metamorphism. Eclogites have been involved in several geodynamic theories. Around 1900, kimberlite studies favoured the idea that eclogite might be abundant in the interior of the Earth. In 1912, Fermor predicted the existence of a dense eclogite-bearing zone in the mantle. This "eclogite layer" hypothesis was still envisaged as late as 1970. The alternative "peridotite" hypothesis became preferred when experimental investigations demonstrated that the gabbro-to-eclogite transition could not coincide with a sharp Mohorovičić discontinuity. Before plate tectonics, high-pressure belts were interpreted as remnants of ophiolite-bearing "geosynclines", metamorphosed by loading during thrust faulting. After the acceptance of plate tectonics, around 1970, the same high-pressure Alpine-type belts came to be considered as former oceanic crust, transformed into eclogite within subduction zones, and subsequently incorporated into mountain belts. Surprisingly, formation of eclogite in "subsidence" zones (i.e. subduction zones) had already been envisaged as early as 1931 by Holmes, the inventor of a convection-current theory. In the 1980s, many authors tried to apply the model of Alpine-type high-pressure belts to eclogites enclosed within the gneisses of ancient orogens, but the question remains obscure nowadays. These eclogites have been involved in the "in situ versus foreign" controversy and in the unresolved enigma of ultrahigh-pressure metamorphism. The latter came under scrutiny in 1984 after the discovery of coesite and diamond in some eclogite-facies rocks. It has been a matter of considerable interest during the last two decades. Currently, the debate is focused on the geodynamic mechanisms responsible for the exhumation of these rocks, a question that will probably remain unresolved for part of the coming century.

A Priori Analysis of a Compressible Flamelet Model using RANS Data for a Dual-Mode Scramjet Combustor

NASA Technical Reports Server (NTRS)

Quinlan, Jesse R.; Drozda, Tomasz G.; McDaniel, James C.; Lacaze, Guilhem; Oefelein, Joseph

2015-01-01

In an effort to make large eddy simulation of hydrocarbon-fueled scramjet combustors more computationally accessible using realistic chemical reaction mechanisms, a compressible flamelet/progress variable (FPV) model was proposed that extends current FPV model formulations to high-speed, compressible flows. Development of this model relied on observations garnered from an a priori analysis of the Reynolds-Averaged Navier-Stokes (RANS) data obtained for the Hypersonic International Flight Research and Experimentation (HI-FiRE) dual-mode scramjet combustor. The RANS data were obtained using a reduced chemical mechanism for the combustion of a JP-7 surrogate and were validated using avail- able experimental data. These RANS data were then post-processed to obtain, in an a priori fashion, the scalar fields corresponding to an FPV-based modeling approach. In the current work, in addition to the proposed compressible flamelet model, a standard incompressible FPV model was also considered. Several candidate progress variables were investigated for their ability to recover static temperature and major and minor product species. The effects of pressure and temperature on the tabulated progress variable source term were characterized, and model coupling terms embedded in the Reynolds- averaged Navier-Stokes equations were studied. Finally, results for the novel compressible flamelet/progress variable model were presented to demonstrate the improvement attained by modeling the effects of pressure and flamelet boundary conditions on the combustion.

Development of manufacturing processes: improved technology for ceramic engine components. Monthly report, August 1977

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

Craig, D.F.; Taylor, A.J.; Weber, G.W.

Progress is described in a research program to develop advanced tooling concepts, processing techniques, and related technology for the economical high-volume manufacture of ceramic engine components. Because of the success of the initial fabrication effort for hot pressing fully dense ceramic turbine blades to shape and/or contour, the effort has been extended to include the fabrication of more complex shapes and the evaluation of alternative pressure-assisted, high-temperature, consolidation methods.

High-Fidelity Three-Dimensional Simulation of the GE90

NASA Technical Reports Server (NTRS)

Turner, Mark G.; Norris, Andrew; Veres, Josphe P.

2004-01-01

A full-engine simulation of the three-dimensional flow in the GE90 94B high-bypass ratio turbofan engine has been achieved. It would take less than 11 hr of wall clock time if starting from scratch through the exploitation of parallel processing. The simulation of the compressor components, the cooled high-pressure turbine, and the low-pressure turbine was performed using the APNASA turbomachinery flow code. The combustor flow and chemistry were simulated using the National Combustor Code (NCC). The engine simulation matches the engine thermodynamic cycle for a sea-level takeoff condition. The simulation is started at the inlet of the fan and progresses downstream. Comparisons with the cycle point are presented. A detailed look at the blockage in the turbomachinery is presented as one measure to assess and view the solution and the multistage interaction effects.

Comparison of Quasi-Conservative Pressure-Based and Fully-Conservative Formulations for the Simulation of Transcritical Flows

NASA Astrophysics Data System (ADS)

Lacaze, Guilhem; Oefelein, Joseph

2016-11-01

High-pressure flows are known to be challenging to simulate due to thermodynamic non-linearities occurring in the vicinity of the pseudo-boiling line. This study investigates the origin of this issue by analyzing the behavior of thermodynamic processes at elevated pressure and low temperature. We show that under transcritical conditions, non-linearities significantly amplify numerical errors associated with construction of fluxes. These errors affect the local density and energy balances, which in turn creates pressure oscillations. For that reason, solvers based on a conservative system of equations that transport density and total energy are subject to unphysical pressure variations in gradient regions. These perturbations hinder numerical stability and degrade the accuracy of predictions. To circumvent this problem, the governing system can be reformulated to a pressure-based treatment of energy. We present comparisons between the pressure-based and fully conservative formulations using a progressive set of canonical cases, including a cryogenic turbulent mixing layer at rocket engine conditions. Department of Energy, Office of Science, Basic Energy Sciences Program.

Perspective: New Recommendations for the Treatment of Systemic Hypertension and their Potential Implications for Glaucoma Management.

PubMed

De Moraes, Carlos Gustavo; Cioffi, George A; Weinreb, Robert N; Liebmann, Jeffrey M

2018-05-10

There is compelling evidence that low systemic blood pressure is associated with glaucoma prevalence and progression. Recently, new guidelines for treatment of systemic hypertension have been implemented and recommend lower target blood pressure. These guidelines may have implications on the rates of glaucoma progression seen in clinical practice and how clinicians should be prepared to identify patients at risk. More importantly, a new paradigm to monitor glaucoma progression is patients treated for systemic hypertension may be warranted in light of these recent changes.

Effects of Head Rotation and Head Tilt on Pharyngeal Pressure Events Using High Resolution Manometry.

PubMed

Kim, Cheol Ki; Ryu, Ju Seok; Song, Sun Hong; Koo, Jung Hoi; Lee, Kyung Duck; Park, Hee Sun; Oh, Yoongul; Min, Kyunghoon

2015-06-01

To observe changes in pharyngeal pressure during the swallowing process according to postures in normal individuals using high-resolution manometry (HRM). Ten healthy volunteers drank 5 mL of water twice while sitting in a neutral posture. Thereafter, they drank the same amount of water twice in the head rotation and head tilting postures. The pressure and time during the deglutition process for each posture were measured with HRM. The data obtained for these two postures were compared with those obtained from the neutral posture. The maximum pressure, area, rise time, and duration in velopharynx (VP) and tongue base (TB) were not affected by changes in posture. In comparison, the maximum pressure and the pre-upper esophageal sphincter (UES) maximum pressure of the lower pharynx in the counter-catheter head rotation posture were lower than those in the neutral posture. The lower pharynx pressure in the catheter head tilting posture was higher than that in the counter-catheter head tilting. The changes in the VP peak and epiglottis, VP and TB peaks, and the VP onset and post-UES time intervals were significant in head tilting and head rotation toward the catheter postures, as compared with neutral posture. The pharyngeal pressure and time parameter analysis using HRM determined the availability of head rotation as a compensatory technique for safe swallowing. Tilting the head smoothes the progress of food by increasing the pressure in the pharynx.

Effects of Head Rotation and Head Tilt on Pharyngeal Pressure Events Using High Resolution Manometry

PubMed Central

Kim, Cheol Ki; Song, Sun Hong; Koo, Jung Hoi; Lee, Kyung Duck; Park, Hee Sun; Oh, Yoongul; Min, Kyunghoon

2015-01-01

Objective To observe changes in pharyngeal pressure during the swallowing process according to postures in normal individuals using high-resolution manometry (HRM). Methods Ten healthy volunteers drank 5 mL of water twice while sitting in a neutral posture. Thereafter, they drank the same amount of water twice in the head rotation and head tilting postures. The pressure and time during the deglutition process for each posture were measured with HRM. The data obtained for these two postures were compared with those obtained from the neutral posture. Results The maximum pressure, area, rise time, and duration in velopharynx (VP) and tongue base (TB) were not affected by changes in posture. In comparison, the maximum pressure and the pre-upper esophageal sphincter (UES) maximum pressure of the lower pharynx in the counter-catheter head rotation posture were lower than those in the neutral posture. The lower pharynx pressure in the catheter head tilting posture was higher than that in the counter-catheter head tilting. The changes in the VP peak and epiglottis, VP and TB peaks, and the VP onset and post-UES time intervals were significant in head tilting and head rotation toward the catheter postures, as compared with neutral posture. Conclusion The pharyngeal pressure and time parameter analysis using HRM determined the availability of head rotation as a compensatory technique for safe swallowing. Tilting the head smoothes the progress of food by increasing the pressure in the pharynx. PMID:26161349

Muscle changes with eccentric exercise: Implications on earth and in space

NASA Technical Reports Server (NTRS)

Hargens, Alan R.; Parazynski, Scott; Aratow, Michael; Friden, Jan

1989-01-01

Recent investigations of fluid pressure, morpholo gy, and enzyme activities of skeletal muscle exercised eccentrically or concentrically in normal human subjects are reviewed. Intramuscular pressures were measured before, during, and after submaximal exercise and correlated with subjective muscle soreness, fiber size, water content, and blood indices of muscle enzymes. High intensity eccentric exercise is characterized by post exercise pain, elevated intramuscular pressures, and swelling of both type 1 and 2 fibers as compared to concentric exercise. Thus, long periods of unaccustomed, high level eccentric contraction may cause muscle injury, fiber swelling, fluid accumulation, elevated intramuscular pressure, and delayed muscle soreness. Training regimens of progressively increasing eccentric exercise, however, cause less soreness and are extremely efficacious in increasing muscle mass and strength. It is proposed that on Earth, postural muscles are uniquely adapted to low levels of prolonged eccentric contraction that are absent during weightlessness. The almost complete absence of eccentric exercise in space may be an important contributor to muscle atrophy and therefore equipment should be designed to integrate eccentric contractions into exercise protocols for long-term spaceflight.

Developmental approach towards high resolution optical coherence tomography for glaucoma diagnostics

NASA Astrophysics Data System (ADS)

Kemper, Björn; Ketelhut, Steffi; Heiduschka, Peter; Thorn, Marie; Larsen, Michael; Schnekenburger, Jürgen

2018-02-01

Glaucoma is caused by a pathological rise in the intraocular pressure, which results in a progressive loss of vision by a damage to retinal cells and the optical nerve head. Early detection of pressure-induced damage is thus essential for the reduction of eye pressure and to prevent severe incapacity or blindness. Within the new European Project GALAHAD (Glaucoma Advanced, Label free High Resolution Automated OCT Diagnostics), we will develop a new low-cost and high-resolution OCT system for the early detection of glaucoma. The device is designed to improve diagnosis based on a new system of optical coherence tomography. Although OCT systems are at present available in ophthalmology centres, high-resolution devices are extremely expensive. The novelty of the new Galahad system is its super wideband light source to achieve high image resolution at a reasonable cost. Proof of concept experiments with cell and tissue Glaucoma test standards and animal models are planned for the test of the new optical components and new algorithms performance for the identification of Glaucoma associated cell and tissue structures. The intense training of the software systems with various samples should result in a increased sensitivity and specificity of the OCT software system.

Getting down to Dollars and Cents: What Do School Districts Spend to Deliver Student-Centered Learning?

ERIC Educational Resources Information Center

Miller, Lawrence J.; Gross, Betheny; Ouijdani, Monica

2012-01-01

In the era of No Child Left Behind and Race to the Top, school districts are under increasing pressure from policymakers to hold all students to high performance standards. In response, a growing number of schools are embracing the principles of student-centered learning (SCL). SCL is a contemporary approach that combines progressive and…

Teaching a Cognitive Behavioral Strategy to Manage Emotions Rational Emotive Behavior Therapy in an Educational Setting

ERIC Educational Resources Information Center

Banks, Tachelle; Zionts, Paul

2009-01-01

The academic and social challenges facing public schools are enormous. For example, the pressure to meet the demands of the current high-stakes testing environment and reach adequate yearly progress (AYP) goals has arguably never been greater (Luna & Turner, 2001; Sanders, 2003). The energy devoted to academics has supplanted the little time spent…

SUSTAINABLE ALLOY DESIGN: SEARCHING FOR RARE EARTH ELEMENT ALTERNATIVES THROUGH CRYSTAL ENGINEERING

DTIC Science & Technology

2016-02-26

Property Maps to Guide Materials Design via Statistical Learning Summer Research Group Meeting – Materials by Design Los Alamos National Laboratory, July...Informatics, Rational design , Quantitative correlative spectroscopy and imaging, DFT, In situ high pressure mechanical property measurements, Superalloy...final, technical, interim, memorandum, master’s thesis, progress, quarterly, research , special, group study, etc. 3. DATES COVERED. Indicate the

The Impact of Physical Activity on Academics in English Classes at the Junior High School Level

ERIC Educational Resources Information Center

Helgeson, John L., Jr.

2013-01-01

The pressure educators, schools, and school districts face with meeting Adequate Yearly Progress on state assessments as a result of the No Child Left Behind Act has made some schools and school district reduce class offerings and time for subjects not considered core subjects. In addition, the rising obesity rates in students have prompted…

Writing in the Content Areas. Research Brief

ERIC Educational Resources Information Center

Walker, Karen

2006-01-01

In an effort for schools to obtain Adequate Yearly Progress, the pressure is on to make certain that students are loaded with as much information as possible in order to score well on the high stakes tests. Writing has continued to move down the list of priorities of what is taught because: it is not being tested or is minimally being assessed.…

Progress toward hydrogen peroxide micropulsion

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

Whitehead, J C; Dittman, M D; Ledebuhr, A G

1999-07-08

A new self-pressurizing propulsion system has liquid thrusters and gas jet attitude control without heavy gas storage vessels. A pump boosts the pressure of a small fraction of the hydrogen peroxide, so that reacted propellant can controllably pressurize its own source tank. The warm decomposition gas also powers the pump and is supplied to the attitude control jets. The system has been incorporated into a prototype microsatellite for terrestrial maneuvering tests. Additional progress includes preliminary testing of a bipropellant thruster, and storage of unstabilized hydrogen peroxide in small sealed tanks.

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

Development of a High-Pressure Gaseous Burner for Calibrating Optical Diagnostic Techniques

NASA Technical Reports Server (NTRS)

Kojima, Jun; Nguyen, Quang-Viet

2003-01-01

In this work-in-progress report, we show the development of a unique high-pressure burner facility (up to 60 atm) that provides steady, reproducible premixed flames with high precision, while having the capability to use multiple fuel/oxidizer combinations. The highpressure facility has four optical access ports for applying different laser diagnostic techniques and will provide a standard reference flame for the development of a spectroscopic database in high-pressure/temperature conditions. Spontaneous Raman scattering (SRS) was the first diagnostic applied, and was used to successfully probe premixed hydrogen-air flames generated in the facility using a novel multi-jet micro-premixed array burner element. The SRS spectral data include contributions from H2, N2, O2, and H2O and were collected over a wide range of equivalence ratios ranging from 0.16 to 4.9 at an initial pressure of 10-atm via a spatially resolved point SRS measurement with a high-performance optical system. Temperatures in fuel-lean to stoichiometric conditions were determined from the ratio of the Stokes to anti-Stokes scattering of the Q-branch of N2, and those in fuel-rich conditions via the rotational temperature of H2. The SRS derived temperatures using both techniques were consistent and indicated that the flame temperature was approximately 500 K below that predicted by adiabatic equilibrium, indicating a large amount of heat-loss at the measurement zone. The integrated vibrational SRS signals show that SRS provides quantitative number density data in high-pressure H2-air flames.

Risk of Progression to Hypertension in a Low-Income Mexican Population with Pre-hypertension and Normal Blood Pressure

PubMed Central

Jimenez-Corona, Aida; Lopez-Ridaura, Ruy; Stern, Michael P; Gonzalez-Villalpando, Clicerio

2007-01-01

BACKGROUND Blood pressure (BP) levels below the pre-hypertension category may be associated with the risk of developing hypertension. We estimated the incidence rates of hypertension in low-income Mexican population according to several subcategories of baseline BP within normal and pre-hypertension categories. METHODS A total of 1572 nonhypertensive men (n=632) and non-pregnant women (n=940), aged 35 to 64 years at baseline, were followed for a median of 5.8 years. Hypertension was defined as systolic blood pressure (SBP) ≥140 mm Hg, diastolic blood pressure (DBP) ≥90 mm Hg, or self-reported physician diagnosis with anti-hypertensive medications. RESULTS During follow-up, 267 subjects developed hypertension, of whom 83 were men and 184 were women. Age-adjusted incidence rate was higher in women (37.1 per 1000 person-years) than in men (23.7 per 1000 person-years). There was a significant association between BP levels at baseline and hypertension incidence even within the normal category. For the upper levels of normal SBP (110-119 mm Hg), the HR (95%CI) was 2.43 (1.50-3.93) in women and 2.44 (1.05-5.69) in men, compared with SBP <110 mm Hg. For the upper levels of normal DBP (70-79 mm Hg), the HR (95%CI) was 2.33 (1.65-3.31) in women and 1.80 (0.92-3.52) in men, compared with DBP <70 mm Hg, after adjustment for recognized predictors. CONCLUSIONS High risk of hypertension incidence was associated with levels of BP even within the normal category. This information could help define a population at high risk of progression to hypertension, in order to establish preventive measures. PMID:17765131

Prehypertension: risk stratification and management considerations.

PubMed

Egan, Brent M; Julius, Stevo

2008-10-01

Approximately 37% of US adults are prehypertensive; about 31 million have blood pressures in the range of 130-139/85-89 mm Hg. These stage 2 prehypertensives have threefold greater risk for developing hypertension and twofold higher risk for cardiovascular events than normotensives. Lifestyle changes only are recommended for most prehypertensives, but evidence for community-wide effectiveness is limited. Projected numbers needed to treat to prevent a cardiovascular event are similar for stage 2 prehypertension and stage 1 hypertension when both groups are matched for concomitant risk factors. However, no clinical trials document that pharmacotherapy reduces cardiovascular events in stage 2 prehypertension. The Trial of Preventing Hypertension demonstrated that angiotensin receptor blockade safely lowers blood pressure and prevents or delays progression to hypertension in stage 2 prehypertensives. We believe it is reasonable for clinicians to identify stage 2 prehypertensives at high absolute risk for progression to hypertension and cardiovascular events, and to treat them with a renin-angiotensin system blocker when lifestyle changes alone are ineffective.

The role of turbulence-flow interactions in L- to H-mode transition dynamics: recent progress

NASA Astrophysics Data System (ADS)

Schmitz, L.

2017-02-01

Recent experimental and simulation work has substantially advanced the understanding of L-mode plasma edge turbulence and plasma flows and their mutual interaction across the L-H transition. Flow acceleration and E   ×   B shear flow amplification via the turbulent Reynolds stress have been directly observed in multiple devices, using multi-tip probe arrays, Doppler backscattering, beam emission spectroscopy, and gas puff imaging diagnostics. L-H transitions characterized by limit-cycle oscillations (LCO) allow probing of the trigger dynamics and the synergy of turbulence-driven and pressure-gradient-driven flows with high spatio-temporal resolution. L-mode turbulent structures exhibit characteristic changes in topology (tilting) and temporal and radial correlation preceding the L-H transition. Long-range toroidal flow correlations increase preceding edge-transport-barrier formation. The energy transfer from the turbulence spectrum to large-scale axisymmetric flows has been quantified in L-LCO and fast L-H transitions in several devices. After formation of a transient barrier, the increasing ion pressure gradient (via the E   ×   B flow shear associated with diamagnetic flow) sustains fluctuation suppression and secures the transition to H-mode. Heuristic models of the L-H trigger dynamics have progressed from 0D predator-prey models to 1D extended models, including neoclassical ion flow-damping and pressure-gradient evolution. Initial results from 2D and 3D reduced fluid models have been obtained for high-collisionality regimes.

Progressive Fracture of Fiber Composite Thin Shell Structures Under Internal Pressure and Axial Loads

NASA Technical Reports Server (NTRS)

Gotsis, Pascal K.; Chamis, Christos C.; Minnetyan, Levon

1996-01-01

Graphite/epoxy composite thin shell structures were simulated to investigate damage and fracture progression due to internal pressure and axial loading. Defective and defect-free structures (thin cylinders) were examined. The three different laminates examined had fiber orientations of (90/0/+/-0)(sub s), where 0 is 45, 60, and 75 deg. CODSTRAN, an integrated computer code that scales up constituent level properties to the structural level and accounts for all possible failure modes, was used to simulate composite degradation under loading. Damage initiation, growth, accumulation, and propagation to fracture were included in the simulation. Burst pressures for defective and defect-free shells were compared to evaluate damage tolerance. The results showed that damage initiation began with matrix failure whereas damage and/or fracture progression occurred as a result of additional matrix failure and fiber fracture. In both thin cylinder cases examined (defective and defect-free), the optimum layup configuration was (90/0/+/-60)(sub s) because it had the best damage tolerance with respect to the burst pressure.

Injurious mechanical ventilation in the normal lung causes a progressive pathologic change in dynamic alveolar mechanics.

PubMed

Pavone, Lucio A; Albert, Scott; Carney, David; Gatto, Louis A; Halter, Jeffrey M; Nieman, Gary F

2007-01-01

Acute respiratory distress syndrome causes a heterogeneous lung injury, and without protective mechanical ventilation a secondary ventilator-induced lung injury can occur. To ventilate noncompliant lung regions, high inflation pressures are required to 'pop open' the injured alveoli. The temporal impact, however, of these elevated pressures on normal alveolar mechanics (that is, the dynamic change in alveolar size and shape during ventilation) is unknown. In the present study we found that ventilating the normal lung with high peak pressure (45 cmH(2)0) and low positive end-expiratory pressure (PEEP of 3 cmH(2)O) did not initially result in altered alveolar mechanics, but alveolar instability developed over time. Anesthetized rats underwent tracheostomy, were placed on pressure control ventilation, and underwent sternotomy. Rats were then assigned to one of three ventilation strategies: control group (n = 3, P control = 14 cmH(2)O, PEEP = 3 cmH(2)O), high pressure/low PEEP group (n = 6, P control = 45 cmH(2)O, PEEP = 3 cmH(2)O), and high pressure/high PEEP group (n = 5, P control = 45 cmH(2)O, PEEP = 10 cmH(2)O). In vivo microscopic footage of subpleural alveolar stability (that is, recruitment/derecruitment) was taken at baseline and than every 15 minutes for 90 minutes following ventilator adjustments. Alveolar recruitment/derecruitment was determined by measuring the area of individual alveoli at peak inspiration (I) and end expiration (E) by computer image analysis. Alveolar recruitment/derecruitment was quantified by the percentage change in alveolar area during tidal ventilation (%I - E Delta). Alveoli were stable in the control group for the entire experiment (low %I - E Delta). Alveoli in the high pressure/low PEEP group were initially stable (low %I - E Delta), but with time alveolar recruitment/derecruitment developed. The development of alveolar instability in the high pressure/low PEEP group was associated with histologic lung injury. A large change in lung volume with each breath will, in time, lead to unstable alveoli and pulmonary damage. Reducing the change in lung volume by increasing the PEEP, even with high inflation pressure, prevents alveolar instability and reduces injury. We speculate that ventilation with large changes in lung volume over time results in surfactant deactivation, which leads to alveolar instability.

Different Relevance of Peripheral, Central or Nighttime Blood Pressure Measurements in the Prediction of Chronic Kidney Disease Progression in Patients with Mild or No-Proteinuria.

PubMed

Kuczera, Piotr; Kwiecień, Katarzyna; Adamczak, Marcin; Bączkowska, Teresa; Gozdowska, Jolanta; Madziarska, Katarzyna; Augustyniak-Bartosik, Hanna; Klinger, Marian; Durlik, Magdalena; Ritz, Eberhard; Wiecek, Andrzej

2018-05-10

Arterial hypertension is one of the leading factors aggravating the course of chronic kidney disease (CKD). It seems that the novel parameters used in the assessment of the blood pressure (BP) load (i.e. central blood pressure, nighttime blood pressure) may be more precise in predicting the cardiovascular risk and the progression of CKD in comparison with the traditional peripheral blood pressure measurements in the office conditions. The aim of the study was to assess the impact of the central, or nighttime blood pressure on the progression of CKD in patients with mild or no-proteinuria (autosomal, dominant polycystic kidney disease or IgA nephropathy). In each of the enrolled 46 patients with CKD stage 3 or 4, serum creatinine concentration was assessed, eGFR (MDRD) was calculated, also central blood pressure and pulse wave velocity (PWV) was assessed and the 24-hour ambulatory blood pressure monitoring (ABPM) was conducted at the beginning of the study and then repeated after one-year observation period. During the observation period mean eGFR decreased from 44.1 (33.2-50.6) mL/min to 36.7 (29.7-46.3) mL/min. No significant differences were observed in the peripheral blood pressure or central blood pressure parameters. After one-year observation period the values of diastolic blood pressure dipping during the night significantly decreased from 16 (13-19) mmHg to 12 (10-15) mmHg; p< 0.05. The values of systolic dipping during the night or the mean BP values recorded in ABPM did not change significantly. Additionally, no significant differences in the PWV values were found. In the multivariate regression model the change of serum creatinine concentration was explained by the initial diastolic dipping values. 1. In patients with CKD stages 3 or 4 and mild or no- proteinuria, peripheral and central blood pressure did not change significantly during a one-year observation period despite the significant decline of eGFR and seems not to participate in the CKD progression. 2. Reduced magnitude of the diastolic dipping, which reflects the increase of diastolic blood pressure load during the nighttime, may play an important role in the pathogenesis of deterioration of kidney function in these patients. © 2018 The Author(s). Published by S. Karger AG, Basel.

Sleep, circadian rhythms, and psychomotor vigilance.

PubMed

Van Dongen, Hans P A; Dinges, David F

2005-04-01

Psychomotor vigilance performance is highly relevant to athletic performance. It is influenced by a sleep homeostatic process, which builds up pressure for sleep during wakefulness and dissipates this pressure during sleep, and a circadian rhythm process, which produces a waxing and waning of pressure for wakefulness over a 24 hours of the day. During total sleep deprivation, these two processes cause performance to deteriorate progressively over days, modulated within days by further performance reductions at night and relative improvements during the daytime. As the homeostatic pressure for sleep builds up higher across prolonged wakefulness, the rate of dissipation of that pressure during subsequent sleep is enhanced exponentially, so that even brief periods of sleep provide significant performance recuperation. Nevertheless, sleep restriction practiced on a chronic basis induces cumulative performance deficits of the same order of magnitude as observed during total sleep deprivation. There are also considerable individual differences in the degree of vulnerability to performance impairment from sleep loss, and these differences represent a trait.

Quasi-dynamic pressure and temperature initiated β<-->δ solid phase transitions in HMX

NASA Astrophysics Data System (ADS)

Zaug, Joseph M.; Farber, Daniel L.; Craig, Ian M.; Blosch, Laura L.; Shuh, David K.; Hansen, Donald W.; Aracne-Ruddle, Chantel M.

2000-04-01

The phase transformation of β-HMX (>0.5% RDX) to δ phase has been studied for over twenty years and more recently with an high-contrast optical second harmonic generation technique. Shock studies of the plastic binder composites of HMX have indicated that the transition is perhaps irreversible, a result that concurs with the static pressure results published by F. Goetz et al. [1] in 1978. However, the stability field favors the β polymorph over δ as pressure is increased (up to 5.4 GPa) along any thermodynamically reasonable isotherm. In this experiment, strict control of pressure and temperature is maintained while x-ray and optical diagnostics are applied to monitor the conformational dynamics of HMX. Unlike the temperature induced β→δ transition, the pressure induced is heterogeneous in nature. The 1 bar 25 °C δ→β transition is not immediate, occuring over tens of hours. Transition points and kinetics are path dependent and consequently this paper describes our work in progress.

Conventional empirical law reverses in the phase transitions of 122-type iron-based superconductors

DOE PAGES

Yu, Zhenhai; Wang, Lin; Wang, Luhong; ...

2014-11-24

Phase transition of solid-state materials is a fundamental research topic in condensed matter physics, materials science and geophysics. It has been well accepted and widely proven that isostructural compounds containing different cations undergo same pressure-induced phase transitions but at progressively lower pressures as the cation radii increases. However, we discovered that this conventional law reverses in the structural transitions in 122-type iron-based superconductors. In this report, a combined low temperature and high pressure X-ray diffraction (XRD) measurement has identified the phase transition curves among the tetragonal (T), orthorhombic (O) and the collapsed-tetragonal (cT) phases in the structural phase diagram ofmore » the iron-based superconductor AFe 2As 2 (A = Ca, Sr, Eu, and Ba). As a result, the cation radii dependence of the phase transition pressure (T → cT) shows an opposite trend in which the compounds with larger ambient radii cations have a higher transition pressure.« less

Temperature and pressure dependence of the optical properties of Cr3+-doped Gd3Ga5O12 nanoparticles.

PubMed

Martín-Rodríguez, R; Valiente, R; Rodríguez, F; Bettinelli, M

2011-07-01

Since the crystal-field strength at the Cr(3+) site is very close to the excited-state crossover (ESCO), this work investigates the optical properties of Cr(3+)-doped Gd(3)Ga(5)O(12) (GGG) nanoparticles as a function of temperature and pressure in order to establish the effect of the ESCO on the optical behaviour of nanocrystalline GGG. Luminescence, time-resolved emission and lifetime measurements have been performed on GGG:0.5% Cr(3+) nanoparticles in the 25-300 K temperature range, as well as under hydrostatic pressure up to 20 GPa. We show how low temperature and high pressure progressively transforms Cr(3+)(4)T(2) --> (4)A(2) broadband emission into a ruby-like (2)E --> (4)A(2) luminescence. This behaviour together with the lifetime dependence on pressure and temperature are explained on the basis of the spin-orbit interaction between the (4)T(2) and (2)E states of Cr(3+).

Shock-induced fine-grained recrystallization of olivine - Evidence against subsolidus reduction of Fe/2+/

NASA Technical Reports Server (NTRS)

Ahrens, T. J.; Tsay, F.-D.; Live, D. H.

1976-01-01

Electron spin resonance (ESR) studies have been carried out on three single grains of terrestrial olivine (Fo90) shock loaded along the 010 line to peak pressures of 280, 330, and 440 kbar. The results indicate that neither metallic Fe similar to that observed in returned lunar soils nor paramagnetic Fe(3+) caused by oxidation of Fe(2+) has been produced in these shock experiments. Trace amounts of Mn (2+) have been detected in both shocked and unshocked olivine. The ESR signals of Mn(2+) show spectral features which are found to correlate with the degree of shock-induced recrystallization observed petrographically. The increasing mass fraction of recrystallized olivine correlates with increasing shock pressures. This phenomenon is modelled assuming it results from the progressive effect of the shock-induced transformation of the olivine to a yet unknown high-pressure phase and its subsequent reversion to the low-pressure olivine phase. The mass fraction of recrystallized material is predicted to be nearly linear with shock pressure.

Biomarkers of Renal Tumor Burden and Progression in TSC

DTIC Science & Technology

2012-09-01

code) Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std. Z39.18 Biomarkers of Renal Tumor Burden and Progression in TSC Dr. Elahna Paul 1...appearance and growth rates) and renal function parameters (e.g. blood pressure, serum chemistries, urinalysis and urine chemistries). (2) Measure...and renal function parameters (e.g. blood pressure, serum chemistries, urinalysis and urine chemistries). (2) Measure soluble growth factors

Critical temperatures in the cephalopod Sepia officinalis investigated using in vivo 31P NMR spectroscopy.

PubMed

Melzner, Frank; Bock, Christian; Pörtner, Hans-O

2006-03-01

The present study was designed to test the hypothesis of an oxygen limitation defining thermal tolerance in the European cuttlefish (Sepia officinalis). Mantle muscle organ metabolic status and pHi were monitored using in vivo 31P NMR spectroscopy, while mantle muscle performance was determined by recording mantle cavity pressure oscillations during ventilation and spontaneous exercise. Under control conditions (15 degrees C), changes in muscle phospho-L-arginine (PLA) and inorganic phosphate (Pi) levels could be linearly related to frequently occurring, high-pressure mantle contractions with pressure amplitudes (MMPA) of >0.2 kPa. Accordingly, mainly MMPA of >2 kPa affected muscle PLA reserves, indicating that contractions with MMPA of <2 kPa only involve the thin layers of aerobic circular mantle musculature. On average, no more than 20% of muscle PLA was depleted during spontaneous exercise under control conditions. Subjecting animals to acute thermal change at an average rate of 1 deg. h-1 led to significant Pi accumulation (equivalent to PLA breakdown) and decrements in the free energy of ATP hydrolysis (dG/dzeta) at both ends of the temperature window, starting at mean critical temperatures (Tc) of 7.0 and 26.8 degrees C, respectively. Frequent groups of high-pressure mantle contractions could not (in the warm) or only partially (in the cold) be related to net PLA breakdown in mantle muscle, indicating an oxygen limitation of routine metabolism rather than exercise-related phosphagen use. We hypothesize that it is mainly the constantly working radial mantle muscles that become progressively devoid of oxygen. Estimates of very low dG/dzeta values (-44 kJ mol-1) in this compartment, along with correlated stagnating ventilation pressures in the warm, support this hypothesis. In conclusion, we found evidence for an oxygen limitation of thermal tolerance in the cuttlefish Sepia officinalis, as indicated by a progressive transition of routine mantle metabolism to an anaerobic mode of energy production.

High-dependency care: experiences of the psychosocial work environment.

PubMed

Rahman, Hanif Abdul; Naing, Lin; Abdul-Mumin, Khadizah

2017-11-23

to explore high-dependency care nurses' experiences of their psychosocial work environment. four focus groups were conducted with 23 emergency and critical care hospital nurses in Brunei. All sessions were recorded, transcribed verbatim and analysed using inductive-approach thematic analysis. three major themes were identified. 'Specialisation/specific skills' explained a fundamental requirement for the high-dependency care nurses to work effectively and efficiently in their workplace. 'Task completion' narrated the pressure they experienced to complete their tasks within time constraints exacerbated by a reduced number of staff. 'Acknowledgement' signified their need for fair and adequate reward for their hard work through career progression and promotion. this study facilitates the design of future interventions and policies that promote a healthy psychosocial work environment by ensuring nurses working in these areas have the required specialisation skills, there is a balance of workload and nurse-to-patient ratios, and they are offered fairness and equity in career progression and promotion.

Remote sensing of atmospheric pressure and sea state using laser altimeters

NASA Technical Reports Server (NTRS)

Gardner, C. S.

1985-01-01

Short-pulse multicolor laser ranging systems are currently being developed for satellite ranging applications. These systems use Q-switched pulsed lasers and streak-tube cameras to provide timing accuracies approaching a few picoseconds. Satellite laser ranging systems have been used to evaluate many important geophysical phenomena such as fault motion, polar motion and solid earth tides, by measuring the orbital perturbations of retroreflector equipped satellites. Some existing operational systems provide range resolution approaching a few millimeters. There is currently considerable interest in adapting these highly accurate systems for use as airborne and satellite based altimeters. Potential applications include the measurement of sea state, ground topography and atmospheric pressure. This paper reviews recent progress in the development of multicolor laser altimeters for use in monitoring sea state and atmospheric pressure.

Structural phase transitions in Bi2Se3 under high pressure

PubMed Central

Yu, Zhenhai; Wang, Lin; Hu, Qingyang; Zhao, Jinggeng; Yan, Shuai; Yang, Ke; Sinogeikin, Stanislav; Gu, Genda; Mao, Ho-kwang

2015-01-01

Raman spectroscopy and angle dispersive X-ray diffraction (XRD) experiments of bismuth selenide (Bi2Se3) have been carried out to pressures of 35.6 and 81.2 GPa, respectively, to explore its pressure-induced phase transformation. The experiments indicate that a progressive structural evolution occurs from an ambient rhombohedra phase (Space group (SG): R-3m) to monoclinic phase (SG: C2/m) and eventually to a high pressure body-centered tetragonal phase (SG: I4/mmm). Evidenced by our XRD data up to 81.2 GPa, the Bi2Se3 crystallizes into body-centered tetragonal structures rather than the recently reported disordered body-centered cubic (BCC) phase. Furthermore, first principles theoretical calculations favor the viewpoint that the I4/mmm phase Bi2Se3 can be stabilized under high pressure (>30 GPa). Remarkably, the Raman spectra of Bi2Se3 from this work (two independent runs) are still Raman active up to ~35 GPa. It is worthy to note that the disordered BCC phase at 27.8 GPa is not observed here. The remarkable difference in atomic radii of Bi and Se in Bi2Se3 may explain why Bi2Se3 shows different structural behavior than isocompounds Bi2Te3 and Sb2Te3. PMID:26522818

Structural phase transitions in Bi 2Se 3 under high pressure

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

Yu, Zhenhai; Gu, Genda; Wang, Lin

2015-11-02

Raman spectroscopy and angle dispersive X-ray diffraction (XRD) experiments of bismuth selenide (Bi 2Se 3) have been carried out to pressures of 35.6 and 81.2 GPa, respectively, to explore its pressure-induced phase transformation. The experiments indicate that a progressive structural evolution occurs from an ambient rhombohedra phase (Space group (SG): R-3m) to monoclinic phase (SG: C2/m) and eventually to a high pressure body-centered tetragonal phase (SG: I4/mmm). Evidenced by our XRD data up to 81.2 GPa, the Bi 2Se 3 crystallizes into body-centered tetragonal structures rather than the recently reported disordered body-centered cubic (BCC) phase. Furthermore, first principles theoretical calculationsmore » favor the viewpoint that the I4/mmm phase Bi 2Se 3 can be stabilized under high pressure (>30 GPa). Remarkably, the Raman spectra of Bi 2Se 3 from this work (two independent runs) are still Raman active up to ~35 GPa. Furthermore, it is worthy to note that the disordered BCC phase at 27.8 GPa is not observed here. The remarkable difference in atomic radii of Bi and Se in Bi 2Se 3 may explain why Bi 2Se 3 shows different structural behavior than isocompounds Bi 2Te 3 and Sb 2Te 3.« less

Study on biphasic material model and mechanical analysis of knee joint cartilage

NASA Astrophysics Data System (ADS)

Nakatani, A.; Sakashita, A.

2008-02-01

A material model of articular cartilage is formulated, and fundamental problems are analyzed. The soft tissue is assumed to comprise two phases: solid and fluid. The biphasic theory proposed by Spilker and Suh (1990) to deal with such materials is reviewed, and some new additional analyses are carried out on the basis of this theory. Assuming the elasticity for the solid phase and introducing the pressure, which is defined by the product of the volume change and penalty coefficient, it is shown that the viscoelastic property of the soft tissue can be reproduced. A preferable solution is obtained for the solid phase by using the reduction integral, even if a high-order interpolation function is used. However, the high-order element cannot satisfactorily capture the velocity distribution of fluids. The pressure distribution is studied by assuming the change in the surface characteristics of the cartilage tissue with the progress of osteoarthritis. The pressure is strongly related to the lubrication conditions, i.e., perfect lubrication, perfect adhesion, and partial adhesion.

Blood pressure and risk of cancer progression - A possible connection with salt and voltage-gated sodium channel.

PubMed

Djamgoz, Mustafa B A

2015-11-01

Although it is well known that high blood pressure promotes cancer, the underlying cause(s) is not well understood. Here, we advance the hypothesis that the extracellular sodium level could be a contributing factor. The hypothesis is based upon emerging evidence showing (i) that voltage-gated sodium channels are expressed de novo in cancer cells and tissues, and (ii) that the influx of sodium from the extracellular medium into cancer cells, mediated by the channel activity, promotes their metastatic potential. Clinical and lifestyle implications of the hypothesis are discussed. Copyright © 2015 Elsevier Ltd. All rights reserved.

Columnar Transitions in Microscale Evaporating Liquid Jets

NASA Astrophysics Data System (ADS)

Hunter, Hanif; Glezer, Ari

2007-11-01

Microscale evaporating liquid jets that are injected into a quiescent gaseous medium having adjustable ambient pressure are investigated over a range of jet speeds using a shadowgraph technique. The jets are formed by a laser-drilled 10 μm nozzle from a small-scale pressurized reservoir, and sub-atmospheric ambient pressure is maintained using a controllable, metered Venturi pump. The near-field jet features are captured by shadowgraph imaging using a pulsed ND-Yag laser and a 12 bit CCD camera where the field of view measured 200 μm on the side. As the ambient pressure is reduced, the jet column undergoes a series of spectacular transitions that are first marked by the appearance of vapor bubbles within the jet column. The transitions progress from columnar instabilities to series of column bifurcations to high-order branching and film formation and culminate in conical atomization of the jet column. In addition to the effects of the ambient pressure, the present investigation also considers effects of the liquid surface tension and vapor pressure on the onset, evolution, and hysteresis of the columnar transitions.

Designer Diamonds: Applications in Iron-based Superconductors and Lanthanides

NASA Astrophysics Data System (ADS)

Vohra, Yogesh

2013-06-01

This talk will focus on the recent progress in the fabrication of designer diamond anvils as well as scientific applications of these diamonds in static high pressure research. The two critical parameters that have emerged in the microwave plasma chemical vapor deposition of designer diamond anvils are (1) the precise [100] alignment of the starting diamond substrate and (2) balancing the competing roles of parts per million levels of nitrogen and oxygen in the diamond growth plasma. The control of these parameters results in the fabrication of high quality designer diamonds with culet size in excess of 300 microns in diameter. The three different applications of designer diamond anvils will be discussed (1) simultaneous electrical resistance and crystal structure measurements using a synchrotron source on Iron-based superconductors with data on both electron and hole doped BaFe2As2 materials and other novel superconducting materials (2) high-pressure high-temperature melting studies on metals using eight-probe Ohmic heating designer diamonds and (3) high pressure low temperature studies on magnetic behavior of 4f-lanthanide metals using four-probe electrical resistance measurements and complementary neutron diffraction studies on a spallation neutron source. Future opportunities in boron-doped conducting designer diamond anvils as well as fabrication of two-stage designer diamonds for ultra high pressure experiments will also be presented. This work was supported by the Department of Energy (DOE) - National Nuclear Security Administration (NNSA) under Grant No. DE-FG52-10NA29660.

Is high myopia a risk factor for visual field progression or disk hemorrhage in primary open-angle glaucoma?

PubMed

Nitta, Koji; Sugiyama, Kazuhisa; Wajima, Ryotaro; Tachibana, Gaku

2017-01-01

The purpose of this study was to clarify differences between highly myopic and non-myopic primary open-angle glaucoma (POAG) patients, including normal-tension glaucoma patients. A total of 269 POAG patients were divided into two groups: patients with ≥26.5 mm of axial length (highly myopic group) and patients with <24.0 mm of axial length (non-myopic group). We analyzed 53 highly myopic and 93 non-myopic POAG patients. Age at first visit of the highly myopic group was significantly less than that of the non-myopic group ( P <0.0001). Baseline intraocular pressures (IOPs) showed no significant differences. Follow-up IOPs of the non-myopic group were significantly lower than those of the highly myopic group ( P =0.0009). According to the mean deviation definition of progression, the cumulative probability of non-progression of visual field (VF) loss was significantly greater in the highly myopic group (10-year survival rate, 73.7%±6.8%) than in the non-myopic group (10-year survival rate, 46.3%±5.8%; log-rank test, P =0.0142). The occurrence of disk hemorrhage (DH) in the non-myopic group (1.60±3.04) was significantly greater than that in the highly myopic group (0.93±2.13, P =0.0311). The cumulative probability of DH was significantly lower in the highly myopic group (10-year survival rate, 26.4%±5.4%) than in the non-myopic group (10-year survival rate, 47.2%±6.6%, P =0.0413). Highly myopic POAG is considered as a combination of myopic optic neuropathy and glaucomatous optic neuropathy (GON). If GON is predominant, it has frequent DH and more progressive VF loss. However, when the myopic optic neuropathy is predominant, it has less DH and less progressive VF loss.

PHASE BEHAVIOR OF THE REACTANTS, PRODUCTS AND CATALYSTS INVOLVED IN THE ALLYLIC EPOXIDATION OF TRANS-2-HEXEN-1-OL TO (2R,3R)-(+)-3-PROPYLOXIRAMETHANOL IN HIGH PRESSURE CARBON DIOXIDE. (R824731)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

[Prevention of pressure ulcer (bedsore)].

PubMed

Sedmak, Dijana; Vrhovec, Marina; Huljev, Dubravko

2013-10-01

Although progress in many fields of science, medicine and technology is evident, we are still witnessing the appearance of bedsores and its consequences. However, in the last fifty years there has been considerable progress in the understanding of its causes, prevention and treatment. Prevention and treatment of pressure ulcers are complicated by the many misconceptions. However, with due knowledge of the process of healing of acute and chronic wounds and of the pathophysiological processes, in many cases chronic wounds, like pressure ulcers, can now be prevented and cured, and thus reduce the cost of treatment, as well as the mortality rate.

A novel live cell imaging system reveals a reversible hydrostatic pressure impact on cell cycle progression.

PubMed

Brooker, Holly R; Gyamfi, Irene A; Wieckowska, Agnieszka; Brooks, Nicholas J; Mulvihill, Daniel P; Geeves, Michael A

2018-06-21

Life is dependent upon the ability of a cell to rapidly respond to changes in environment. Small perturbations in local environments change the ability of molecules to interact and hence communicate. Hydrostatic pressure provides a rapid non-invasive, fully-reversible method for modulating affinities between molecules both in vivo and in vitro We have developed a simple fluorescence imaging chamber that allows intracellular protein dynamics and molecular events to be followed at pressures up to 200 bar in living cells. Using yeast we investigate the impact of hydrostatic pressure upon cell growth and cell cycle progression. While 100 bar has no affect upon viability, it induces a delay in chromosome segregation, resulting in the accumulation of long-undivided-bent cells, consistent with disruption of the cytoskeletons. This delay is independent of stress signalling and induces synchronisation of cell-cycle progression. Equivalent affects were observed in Candida albicans , with pressure inducing a reversible cell-cycle delay and hyphal growth. We present a simple novel non-invasive fluorescence microscopy based approach to transiently impact molecular dynamics to visualise, dissect and study signalling pathways and cellular processes in living cells. © 2018. Published by The Company of Biologists Ltd.

Properties of iron under core conditions

NASA Astrophysics Data System (ADS)

Brown, J. M.

2003-04-01

Underlying an understanding of the geodynamo and evolution of the core is knowledge of the physical and chemical properties of iron and iron mixtures under high pressure and temperature conditions. Key properties include the viscosity of the fluid outer core, thermal diffusivity, equations-of-state, elastic properties of solid phases, and phase equilibria for iron and iron-dominated mixtures. As is expected for work that continues to tax technological and intellectual limits, controversy has followed both experimental and theoretical progress in this field. However, estimates for the melting temperature of the inner core show convergence and the equation-of-state for iron as determined in independent experiments and theories are in remarkable accord. Furthermore, although the structure and elastic properties of the solid inner-core phase remains uncertain, theoretical and experimental underpinnings are better understood and substantial progress is likely in the near future. This talk will focus on an identification of properties that are reasonably well known and those that merit further detailed study. In particular, both theoretical and experimental (static and shock wave) determinations of the density of iron under extreme conditions are in agreement at the 1% or better level. The behavior of the Gruneisen parameter (which determines the geothermal gradient and controls much of the outer core heat flux) is constrained by experiment and theory under core conditions for both solid and liquid phases. Recent experiments and theory are suggestive of structure or structures other than the high-pressure hexagonal close-packed (HCP) phase. Various theories and experiments for the elasticity of HCP iron remain in poor accord. Uncontroversial constraints on core chemistry will likely never be possible. However, reasonable bounds are possible on the basis of seismic profiles, geochemical arguments, and determinations of sound velocities and densities at high pressure and temperature.

Contemporary rates and predictors of fast progression of chronic kidney disease in adults with and without diabetes mellitus.

PubMed

Go, Alan S; Yang, Jingrong; Tan, Thida C; Cabrera, Claudia S; Stefansson, Bergur V; Greasley, Peter J; Ordonez, Juan D

2018-06-22

Chronic kidney disease (CKD) is highly prevalent but identification of patients at high risk for fast CKD progression before reaching end-stage renal disease in the short-term has been challenging. Whether factors associated with fast progression vary by diabetes status is also not well understood. We examined a large community-based cohort of adults with CKD to identify predictors of fast progression during the first 2 years of follow-up in the presence or absence of diabetes mellitus. Within a large integrated healthcare delivery system in northern California, we identified adults with estimated glomerular filtration rate (eGFR) 30-59 ml/min/1.73 m 2 by CKD-EPI equation between 2008 and 2010 who had no previous dialysis or renal transplant, who had outpatient serum creatinine values spaced 10-14 months apart and who did not initiate renal replacement therapy, die or disenroll during the first 2 years of follow-up. Through 2012, we calculated the annual rate of change in eGFR and classified patients as fast progressors if they lost > 4 ml/min/1.73 m 2 per year. We used multivariable logistic regression to identify patient characteristics that were independently associated with fast CKD progression stratified by diabetes status. We identified 36,195 eligible adults with eGFR 30-59 ml/min/1.73 m 2 and mean age 73 years, 55% women, 11% black, 12% Asian/Pacific Islander and 36% with diabetes mellitus. During 24-month follow-up, fast progression of CKD occurred in 23.0% of patients with diabetes vs. 15.3% of patients without diabetes. Multivariable predictors of fast CKD progression that were similar by diabetes status included proteinuria, age ≥ 80 years, heart failure, anemia and higher systolic blood pressure. Age 70-79 years, prior ischemic stroke, current or former smoking and lower HDL cholesterol level were also predictive in patients without diabetes, while age 18-49 years was additionally predictive in those with diabetes. In a large, contemporary population of adults with eGFR 30-59 ml/min/1.73 m 2 , accelerated progression of kidney dysfunction within 2 years affected ~ 1 in 4 patients with diabetes and ~ 1 in 7 without diabetes. Regardless of diabetes status, the strongest independent predictors of fast CKD progression included proteinuria, elevated systolic blood pressure, heart failure and anemia.

Predicting Renal Failure Progression in Chronic Kidney Disease Using Integrated Intelligent Fuzzy Expert System.

PubMed

Norouzi, Jamshid; Yadollahpour, Ali; Mirbagheri, Seyed Ahmad; Mazdeh, Mitra Mahdavi; Hosseini, Seyed Ahmad

2016-01-01

Chronic kidney disease (CKD) is a covert disease. Accurate prediction of CKD progression over time is necessary for reducing its costs and mortality rates. The present study proposes an adaptive neurofuzzy inference system (ANFIS) for predicting the renal failure timeframe of CKD based on real clinical data. This study used 10-year clinical records of newly diagnosed CKD patients. The threshold value of 15 cc/kg/min/1.73 m(2) of glomerular filtration rate (GFR) was used as the marker of renal failure. A Takagi-Sugeno type ANFIS model was used to predict GFR values. Variables of age, sex, weight, underlying diseases, diastolic blood pressure, creatinine, calcium, phosphorus, uric acid, and GFR were initially selected for the predicting model. Weight, diastolic blood pressure, diabetes mellitus as underlying disease, and current GFR(t) showed significant correlation with GFRs and were selected as the inputs of model. The comparisons of the predicted values with the real data showed that the ANFIS model could accurately estimate GFR variations in all sequential periods (Normalized Mean Absolute Error lower than 5%). Despite the high uncertainties of human body and dynamic nature of CKD progression, our model can accurately predict the GFR variations at long future periods.

Structure of Oxide Glass and Melts at High-Pressure: A View from Inelastic X-ray Scattering and 2D Solid-State NMR

NASA Astrophysics Data System (ADS)

Lee, S.; Mysen, B. O.; Fei, Y.; Cody, G. D.; Mao, H.; Eng, P.

2006-12-01

Full understanding of the atomic arrangement of oxides glasses and melts both at ambient and high-pressure has long been one of the fundamental and yet difficult problems in earth sciences, condensed matter physics as well as glass sciences. The structures of archetypal oxide glasses (e.g. SiO2 and B2O3) as well as complex silicate glasses (ternary and quaternary aluminosilicate glasses) at high pressure are essential to elucidate origins of anomalous macroscopic properties of melts and global geophysical processes in the Earth's interior. Recent progress in inelastic x-ray scattering (IXS) with high brilliance 3rd generation synchrotron x-rays combined with DAC techniques allows us to explore pressure-induced changes in the bonding nature of archetypal amorphous oxide, illustrating a new opportunity to study amorphous oxides with IXS (Lee SK et al. Nature Materials 2005, 4, p851). 2 dimensional solid-state NMR have offered much improved resolution over conventional 1D NMR, unveiling previously unknown structural details of amorphous silicates at high pressure (Lee SK. Geochim. Cosmochim. Acta 2005, 69, p3695; J. Phys. Chem. B. 2006, 110, p16408) Here, we report the synchrotron inelastic x-ray scattering results (oxygen and boron K-edge) for divers oxide glasses at pressure up to 40 GPa, revealing the nature of pressure-induced bonding changes and the structure. Direct in-situ measurements provide evidence for a continuous transformation with multiple densification mechanisms. 2D solid-state NMR spectra for silicate and germinate glasses shows detailed information about extent of disorder among framework units at high pressure. The chemical ordering among framework units leads to the formation of ^{[5,6]}Si-O-^{[4]}Si in silicates and ^{[5,6]}Al-O-^{[4]}Si in aluminosilicates. Whereas the densification mechanism can be dependent on the chemical composition and the fraction of non-bridging oxygen, the pressure dependence of both simple and complex multi-component silicate glasses showed similar characteristics: low pressure regime was marked with topological variation without coordination transformation and inter-mediate pressure region (about 5-10 GPa) was characterized by the largest (d(^{[4]}B or ^{[5,6]}Si)/dP) value. Finally high-pressure regime (above 10 GPa) was characterized by a larger energy penalty for coordination transformation than in intermediate pressure regime. These results provide improved prospect for the bonding nature of amorphous materials at high pressure using synchrotron inelastic x-ray scattering and 2D NMR and aid in understanding the microscopic origins of the properties of melts and geological processes in the Earth's interior.

High caloric and sodium intakes as risk factors for progression of retinopathy in type 1 diabetes mellitus.

PubMed

Roy, Monique S; Janal, Malvin N

2010-01-01

To report the association of dietary nutrient intakes in relation to the 6-year progression of diabetic retinopathy (DR) in African American patients with type 1 diabetes mellitus. African American patients with type 1 diabetes who participated in the baseline and 6-year follow-up examinations as part of the New Jersey 725 study were included. At the baseline examination, a food frequency questionnaire was used to document average daily dietary nutrient intakes. Clinical evaluations at baseline and at the 6-year follow-up also included a structured clinical interview, ocular examination, grading of 7 standard field stereoscopic fundus photographs, and blood pressure measurements. Biological evaluations included blood and urine assays. Nutrient intake data were analyzed using DietSys software and nutrient databases developed by the National Cancer Institute. Among the 469 participants at risk for progression of DR, baseline total caloric intake was significantly associated with 6-year incidence of vision-threatening DR (either proliferative DR or macular edema) and of severe hard exudates--after adjusting for clinical risk factors for DR progression. Baseline high sodium intake was a significant and independent risk factor for 6-year incidence of macular edema. In African American patients with type 1 diabetes, high caloric and sodium intakes are significant and independent risk factors for progression to severe forms of DR. Dietary recommendations of low caloric and sodium intakes may be beneficial in relation to the development of DR.

Salt-induced epithelial-to-mesenchymal transition in Dahl salt-sensitive rats is dependent on elevated blood pressure.

PubMed

Wang, Y; Mu, J J; Liu, F Q; Ren, K Y; Xiao, H Y; Yang, Z; Yuan, Z Y

2014-02-01

Dietary salt intake has been linked to hypertension and cardiovascular disease. Accumulating evidence has indicated that salt-sensitive individuals on high salt intake are more likely to develop renal fibrosis. Epithelial-to-mesenchymal transition (EMT) participates in the development and progression of renal fibrosis in humans and animals. The objective of this study was to investigate the impact of a high-salt diet on EMT in Dahl salt-sensitive (SS) rats. Twenty-four male SS and consomic SS-13(BN) rats were randomized to a normal diet or a high-salt diet. After 4 weeks, systolic blood pressure (SBP) and albuminuria were analyzed, and renal fibrosis was histopathologically evaluated. Tubular EMT was evaluated using immunohistochemistry and real-time PCR with E-cadherin and alpha smooth muscle actin (α-SMA). After 4 weeks, SBP and albuminuria were significantly increased in the SS high-salt group compared with the normal diet group. Dietary salt intake induced renal fibrosis and tubular EMT as identified by reduced expression of E-cadherin and enhanced expression of α-SMA in SS rats. Both blood pressure and renal interstitial fibrosis were negatively correlated with E-cadherin but positively correlated with α-SMA. Salt intake induced tubular EMT and renal injury in SS rats, and this relationship might depend on the increase in blood pressure.

A Discrete Element Method Approach to Progressive Localization of Damage in Granular Rocks and Associated Seismicity

NASA Astrophysics Data System (ADS)

Vora, H.; Morgan, J.

2017-12-01

Brittle failure in rock under confined biaxial conditions is accompanied by release of seismic energy, known as acoustic emissions (AE). The objective our study is to understand the influence of elastic properties of rock and its stress state on deformation patterns, and associated seismicity in granular rocks. Discrete Element Modeling is used to simulate biaxial tests on granular rocks of defined grain size distribution. Acoustic Energy and seismic moments are calculated from microfracture events as rock is taken to conditions of failure under different confining pressure states. Dimensionless parameters such as seismic b-value and fractal parameter for deformation, D-value, are used to quantify seismic character and distribution of damage in rock. Initial results suggest that confining pressure has the largest control on distribution of induced microfracturing, while fracture energy and seismic magnitudes are highly sensitive to elastic properties of rock. At low confining pressures, localized deformation (low D-values) and high seismic b-values are observed. Deformation at high confining pressures is distributed in nature (high D-values) and exhibit low seismic b-values as shearing becomes the dominant mode of microfracturing. Seismic b-values and fractal D-values obtained from microfracturing exhibit a linear inverse relationship, similar to trends observed in earthquakes. Mode of microfracturing in our simulations of biaxial compression tests show mechanistic similarities to propagation of fractures and faults in nature.

Quantitative X-ray measurements of high-pressure fuel sprays from a production heavy duty diesel injector

NASA Astrophysics Data System (ADS)

Ramírez, A. I.; Som, S.; Aggarwal, Suresh K.; Kastengren, A. L.; El-Hannouny, E. M.; Longman, D. E.; Powell, C. F.

2009-07-01

A quantitative and time-resolved X-ray radiography technique has been used for detailed measurements of high-pressure fuel sprays in the near-nozzle region of a diesel engine injector. The technique provides high spatial and temporal resolution, especially in the relatively dense core region. A single spray plume from a hydraulically actuated electronically controlled unit injector model 315B injector with a 6-hole nozzle was isolated and studied at engine-like densities for two different injection pressures. Optical spray imaging was also employed to evaluate the effectiveness of the shield used to isolate a single spray plume. The steady state fuel distributions for both injection pressures are similar and show a dense spray region along the axis of the spray, with the on-axis spray density decreasing as the spray progresses downstream. The higher injection pressure case exhibits a larger cone angle and spray broadening at the exit of the nozzle. For some time periods, the near-nozzle penetration speed is lower for the high injection pressure case than the low injection pressure case, which is unexpected, but can be attributed to the needle and flow dynamics inside the injector causing slower pressure build-up for the former case. Rate of injection testing was performed to further understand near-nozzle behavior. Mass distribution data were obtained and used to find mass-averaged velocity of the spray. Comparisons of the radiography data with that from a common rail single-hole light duty injectors under similar injection conditions show several significant differences. The current data show a larger cone angle and lower penetration speed than that from the light-duty injector. Moreover, these data display a Gaussian mass distribution across the spray near the injector, whereas in previous light-duty injector measurements, the mass distribution had steeper sides and a flatter peak. Measurements are also used to examine the spray models in the STAR-CD software.

Synthetic ANaB(Na x Li1 - x Mg1)CMg5Si8O22(OH)2 (with x = 0.6, 0.2 and 0) P21/ m amphiboles at high pressure: a synchrotron infrared study

NASA Astrophysics Data System (ADS)

Iezzi, Gianluca; Liu, Zhenxian; Della Ventura, Giancarlo

2009-06-01

The high-pressure behavior of three synthetic amphiboles crystallized with space group P21/ m at room conditions in the system Li2O-Na2O-MgO-SiO2-H2O has been studied by in situ synchrotron infrared absorption spectroscopy. The amphiboles have compositions ANa B(Na x Li1 - x Mg1) CMg5 Si8 O22(OH)2 with x = 0.6, 0.2 and 0.0, respectively. The high- P experiments up to 32 GPa were carried out on the U2A beamline at Brookhaven National Laboratory (NY, USA) using a diamond anvil cell under non-hydrostatic or quasi-hydrostatic conditions. The two most intense absorption bands in the OH-stretching infrared spectra can be assigned to two non-equivalent O-H dipoles in the P21/ m structure, bonded to the same local environment M1M3Mg3-OH-ANa, and pointing toward two differently kinked tetrahedral rings. In all samples these bands progressively merge to give a unique symmetrical absorption with increasing pressure, suggesting a change in symmetry from P21/ m to C2/ m. The pressure at which the transition occurs appears to be linearly correlated to the aggregate B-site dimension. The infrared spectra collected for amphibole B(Na0.2Li0.8Mg1) in the frequency range 50 to 1,400 cm-1 also show a series of changes with increasing pressure. The data reported here support the inference of Iezzi et al. (Am Miner 91:479-482, 2006a) regarding a new high-pressure amphibole polymorph.

Hemodynamic Correlates of Abnormal Aortic Root Dimension in an Adult Population: The Strong Heart Study.

PubMed

de Simone, Giovanni; Roman, Mary J; De Marco, Marina; Bella, Jonathan N; Izzo, Raffaele; Lee, Elisa T; Devereux, Richard B

2015-09-28

We evaluated the relationship of aortic root dimension (ARD) with flow output and both peripheral and central blood pressure, using multivariable equations predicting ideal sex-specific ARD at a given age and body height. We measured echocardiographic diastolic ARD at the sinuses of Valsalva in 3160 adults (aged 42±16 years, 61% women) from the fourth examination of the Strong Heart Study who were free of prevalent coronary heart disease, and we compared measured data with the theoretical predicted value to calculate a z score. Central blood pressure was estimated by applanation tonometry of the radial artery in 2319 participants. ARD z scores were divided into tertiles representing small, normal, and large ARD. Participants with large ARD exhibited greater prevalence of central obesity and higher levels of inflammatory markers and lipids (0.05

Progressive exercise preconditioning protects against circulatory shock during experimental heatstroke.

PubMed

Hung, Ching-Hsia; Chang, Nen-Chung; Cheng, Bor-Chih; Lin, Mao-Tsun

2005-05-01

Heat shock protein (HSP) 72 expression protects against arterial hypotension in rat heatstroke. HSP72 can also be induced in multiple organs, including hearts from rats with endurance exercise. We validated the hypothesis that progressive exercise preconditioning may confer cardiovascular protection during heatstroke by inducing the overexpression of HSP72 in multiple organs. To deal with the matter, we assessed the effects of heatstroke on mean arterial pressure, heart rate, cardiac output, stroke volume, total peripheral vascular resistance, colonic temperature, blood gases, and serum or tissue levels of tumor necrosis factor-alpha (TNF-alpha) in urethane-anesthetized rats pretreated without or with progressive exercise training for 1, 2, or 3 weeks. In addition, HSP72 expression in multiple organs was determined in different groups of animals. Heatstroke was induced by exposing the rats to a high blanket temperature (43 degrees C); the moment at which mean arterial pressure decreased from the peak value was taken as the time of heatstroke onset. Previous exercise training for 3 weeks, but not 1 or 2 weeks, conferred significant protection against hyperthermia, arterial hypotension, decreased cardiac output, decreased stroke volume, decreased peripheral vascular resistance, and increased levels of serum or tissue TNF-alpha during heatstroke and correlated with overexpression of HSP72 in multiple organs, including heart, liver, and adrenal gland. However, 10 days after 3 weeks of progressive exercise training, when HSP72 expression in multiple organs returned to basal values, the beneficial effects exerted by 3 weeks of exercise training were no longer observed. These results strongly suggest that HSP72 preconditioning with progressive exercise training protects against hyperthermia, circulatory shock, and TNF-alpha overproduction during heatstroke.

Severity of spine malalignment on center of pressure progression during level walking in subjects with adolescent idiopathic scoliosis.

PubMed

Chern, Jen-Suh; Kao, Chia-Chi; Lai, Po-Lian; Lung, Chi-Wen; Chen, Wen-Jer

2014-01-01

Center of pressure (CoP) progression during level walking in subjects with Adolescents Idiopathic Scoliosis (AIS) was measured. Participants were divided into three groups according to scoliosis severity. CoP progression among groups was compared quantitatively and qualitatively. The results showed that scoliosis severity affects CoP progression significantly in the hind-foot and forefoot areas. This result indicated that spine alignment might affect the control of heel, ankle and toe rockers in the ankle-foot complex. The effects of scoliosis severity is mainly on the CoP of right foot plantar surface, indicating asymmetrical influence of IS on bilateral lower limb coordination during walking. These results might contribute to musculoskeletal complains over the apparatus within trunk-foot in the later lives of this population.

Increased risk of coronary artery calcification progression in subjects with high baseline Lp(a) levels: The Kangbuk Samsung Health Study.

PubMed

Cho, Jung Hwan; Lee, Da Young; Lee, Eun Seo; Kim, Jihyun; Park, Se Eun; Park, Cheol-Young; Lee, Won-Young; Oh, Ki-Won; Park, Sung-Woo; Rhee, Eun-Jung

2016-11-01

Results from previous studies support the association of lipoprotein(a) [Lp(a)] levels and coronary artery disease risk. In this study, we analyzed the association between baseline Lp(a) levels and future progression of coronary artery calcification (CAC) in apparently healthy Korean adults. A total of 2611 participants (mean age: 41years, 92% mend) who underwent a routine health check-up in 2010 and 2014 were enrolled. Coronary artery calcium score (CACS) were measured by multi-detector computed tomography. Baseline Lp(a) was measured by high-sensitivity immunoturbidimetric assay. Progression of CAC was defined as a change in CACS >0 over four years. Bivariate correlation analyses with baseline Lp(a) and other metabolic parameters revealed age, total cholesterol, HDL-C, LDL-C and CACS to have a significant positive correlation, while body weight, fasting glucose level, blood pressure and triglyceride level were negatively correlated with baseline Lp(a) level. After four years of follow-up, 635 subjects (24.3%) had CAC progression. The participants who had CAC progression were older, composed of more men, more obese, and had higher fasting glucose levels and worse baseline lipid profiles compared to those who did not have CAC progression. The mean serum Lp(a) level was significantly higher in subjects who had CAC progression compared to those who did not (32.5 vs. 28.9mg/dL, p<0.01). When the risk for CAC progression according to baseline Lp(a) was calculated, those with Lp(a) level≥50mg/dL had an odds ratio of 1.333 (95% CI 1.027-1.730) for CAC progression compared to those with Lp(a)<50mg/dL after adjusting for confounding factors. In this study, the subjects who had higher Lp(a) were at significantly higher risk for CAC progression after four years of follow-up, suggesting the role of high Lp(a) in CAC progression. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

CFD Computations for a Generic High-Lift Configuration Using TetrUSS

NASA Technical Reports Server (NTRS)

Pandya, Mohagna J.; Abdol-Hamid, Khaled S.; Parlette, Edward B.

2011-01-01

Assessment of the accuracy of computational results for a generic high-lift trapezoidal wing with a single slotted flap and slat is presented. The paper is closely aligned with the focus of the 1st AIAA CFD High Lift Prediction Workshop (HiLiftPW-1) which was to assess the accuracy of CFD methods for multi-element high-lift configurations. The unstructured grid Reynolds-Averaged Navier-Stokes solver TetrUSS/USM3D is used for the computational results. USM3D results are obtained assuming fully turbulent flow using the Spalart-Allmaras (SA) and Shear Stress Transport (SST) turbulence models. Computed solutions have been obtained at seven different angles-of-attack ranging from 6 -37 . Three grids providing progressively higher grid resolution are used to quantify the effect of grid resolution on the lift, drag, pitching moment, surface pressure and stall angle. SA results, as compared to SST results, exhibit better agreement with the measured data. However, both turbulence models under-predict upper surface pressures near the wing tip region.

A Numerical Investigation of Turbine Noise Source Hierarchy and Its Acoustic Transmission Characteristics: Proof-of-Concept Progress

NASA Technical Reports Server (NTRS)

VanZante, Dale; Envia, Edmane

2008-01-01

A CFD-based simulation of single-stage turbine was done using the TURBO code to assess its viability for determining acoustic transmission through blade rows. Temporal and spectral analysis of the unsteady pressure data from the numerical simulations showed the allowable Tyler-Sofrin modes that are consistent with expectations. This indicated that high-fidelity acoustic transmission calculations are feasible with TURBO.

Progress toward determining the potential of ODS alloys for gas turbine applications

NASA Technical Reports Server (NTRS)

Dreshfield, R. L.; Hoppin, G., III; Sheffler, K.

1983-01-01

The Materials for Advanced Turbine Engine (MATE) Program managed by the NASA Lewis Research Center is supporting two projects to evaluate the potential of oxide dispersion strengthened (ODS) alloys for aircraft gas turbine applications. One project involves the evaluation of Incoloy (TM) MA-956 for application as a combustor liner material. An assessment of advanced engine potential will be conducted by means of a test in a P&WA 2037 turbofan engine. The other project involves the evaluation of Inconel (TM) MA 6000 for application as a high pressure turbine blade material and includes a test in a Garrett TFE 731 turbofan engine. Both projects are progressing toward these engine tests in 1984.

Blood pressure control for diabetic retinopathy

PubMed Central

Do, Diana V; Wang, Xue; Vedula, Satyanarayana S; Marrone, Michael; Sleilati, Gina; Hawkins, Barbara S; Frank, Robert N

2015-01-01

Background Diabetic retinopathy is a common complication of diabetes and a leading cause of visual impairment and blindness. Research has established the importance of blood glucose control to prevent development and progression of the ocular complications of diabetes. Simultaneous blood pressure control has been advocated for the same purpose, but findings reported from individual studies have supported varying conclusions regarding the ocular benefit of interventions on blood pressure. Objectives The primary aim of this review was to summarize the existing evidence regarding the effect of interventions to control or reduce blood pressure levels among diabetics on incidence and progression of diabetic retinopathy, preservation of visual acuity, adverse events, quality of life, and costs. A secondary aim was to compare classes of anti-hypertensive medications with respect to the same outcomes. Search methods We searched a number of electronic databases including CENTRAL as well as ongoing trial registries. We last searched the electronic databases on 25 April 2014. We also reviewed reference lists of review articles and trial reports selected for inclusion. In addition, we contacted investigators of trials with potentially pertinent data. Selection criteria We included in this review randomized controlled trials (RCTs) in which either type 1 or type 2 diabetic participants, with or without hypertension, were assigned randomly to intense versus less intense blood pressure control, to blood pressure control versus usual care or no intervention on blood pressure, or to different classes of anti-hypertensive agents versus placebo. Data collection and analysis Pairs of review authors independently reviewed titles and abstracts from electronic and manual searches and the full text of any document that appeared to be relevant. We assessed included trials independently for risk of bias with respect to outcomes reported in this review. We extracted data regarding trial characteristics, incidence and progression of retinopathy, visual acuity, quality of life, and cost-effectiveness at annual intervals after study entry whenever provided in published reports and other documents available from included trials. Main results We included 15 RCTs, conducted primarily in North America and Europe, that had enrolled 4157 type 1 and 9512 type 2 diabetic participants, ranging from 16 to 2130 participants in individual trials. In 10 of the 15 RCTs, one group of participants was assigned to one or more anti-hypertensive agents and the control group received placebo. In three trials, intense blood pressure control was compared to less intense blood pressure control. In the remaining two trials, blood pressure control was compared with usual care. Five of the 15 trials enrolled type 1 diabetics, and 10 trials enrolled type 2 diabetics. Six trials were sponsored entirely by pharmaceutical companies, seven trials received partial support from pharmaceutical companies, and two studies received support from government-sponsored grants and institutional support. Study designs, populations, interventions, and lengths of follow-up (range one to nine years) varied among the included trials. Overall, the quality of the evidence for individual outcomes was low to moderate. For the primary outcomes, incidence and progression of retinopathy, the quality of evidence was downgraded due to inconsistency and imprecision of estimates from individual studies and differing characteristics of participants. For primary outcomes among type 1 diabetics, one of the five trials reported incidence of retinopathy and one trial reported progression of retinopathy after 4 to 5 years of treatment and follow-up; four of the five trials reported a combined outcome of incidence and progression over the same time interval. Among type 2 diabetics, 5 of the 10 trials reported incidence of diabetic retinopathy and 3 trials reported progression of retinopathy; one of the 10 trials reported a combined outcome of incidence and progression during a 4-to 5-year follow-up period. One trial in which type 2 diabetics participated had reported no primary (or secondary) outcome targeted for this review. The evidence from these trials supported a benefit of more intensive blood pressure control intervention with respect to 4- to 5-year incidence of diabetic retinopathy (estimated risk ratio (RR) 0.80; 95% confidence interval (CI) 0.71 to 0.92) and the combined outcome of incidence and progression (estimated RR 0.78; 95% CI 0.63 to 0.97). The available evidence provided less support for a benefit with respect to 4- to 5-year progression of diabetic retinopathy (point estimate was closer to 1 than point estimates for incidence and combined incidence and progression, and the CI overlapped 1; estimated RR 0.88; 95% CI 0.73 to 1.05). The available evidence regarding progression to proliferative diabetic retinopathy or clinically significant macular edema or moderate to severe loss of best-corrected visual acuity did not support a benefit of intervention on blood pressure: estimated RRs and 95% CIs 0.95 (0.83 to 1.09) and 1.06 (0.85 to 1.33), respectively, after 4 to 5 years of follow-up. Findings within subgroups of trial participants (type 1 and type 2 diabetics; participants with normal blood pressure levels at baseline and those with elevated levels) were similar to overall findings. The adverse event reported most often (7 of 15 trials) was death, yielding an estimated RR 0.86 (95% CI 0.64 to 1.14). Hypotension was reported from three trials; the estimated RR was 2.08 (95% CI 1.68 to 2.57). Other adverse ocular events were reported from single trials. Authors’ conclusions Hypertension is a well-known risk factor for several chronic conditions in which lowering blood pressure has proven to be beneficial. The available evidence supports a beneficial effect of intervention to reduce blood pressure with respect to preventing diabetic retinopathy for up to 4 to 5 years. However, the lack of evidence to support such intervention to slow progression of diabetic retinopathy or to prevent other outcomes considered in this review, along with the relatively modest support for the beneficial effect on incidence, weakens the conclusion regarding an overall benefit of intervening on blood pressure solely to prevent diabetic retinopathy. PMID:25637717

Progression rate from new-onset pre-hypertension to hypertension in Korean adults.

PubMed

Kim, Soo Jeong; Lee, Jakyoung; Nam, Chung Mo; Jee, Sun Ha; Park, Il Soo; Lee, Kyung Jong; Lee, Soon Young

2011-01-01

There are limited studies conducted in Asia to investigate the progression rate to hypertension (HTN). This study was done to estimate the progression rate of new-onset pre-HTN (PreHTN) to HTN during an 8-year follow-up period, and to compare the impact of PreHTN on progression to HTN. A total of 49,228 participants, aged 30 to 54 years with new-onset PreHTN at baseline (1994-1996) from a biennial national medical exam were enrolled and followed up every 2 years until 2004. The incidence rate recorded at each interval and the cumulative incidence rate of HTN were analyzed. Hazard ratio of high-normal and high blood pressure (BP) in men and women was calculated. The cumulative incidence rate for high-normal BP was 27.6% and 26.4% at 2-year follow-up, increased to respectively 64.1% and 55.8% in men and women at the 8-year follow-up. Compared to optimal BP, hazard ratios for men with high-normal BP across all age groups were 3- to 4-fold higher at 2-year, and 2- to 3-fold higher at 8-year follow-up. Hazard ratios for women were about 6-fold higher at 2-year and around 4-fold higher at 8-year follow-up. New PreHTN was a significant predisposing factor for future HTN, in young adults and the effect is more prominent in women.

Pressure dependence of viscosity in supercooled water and a unified approach for thermodynamic and dynamic anomalies of water

PubMed Central

Singh, Lokendra P.; Issenmann, Bruno; Caupin, Frédéric

2017-01-01

The anomalous decrease of the viscosity of water with applied pressure has been known for over a century. It occurs concurrently with major structural changes: The second coordination shell around a molecule collapses onto the first shell. Viscosity is thus a macroscopic witness of the progressive breaking of the tetrahedral hydrogen bond network that makes water so peculiar. At low temperature, water at ambient pressure becomes more tetrahedral and the effect of pressure becomes stronger. However, surprisingly, no data are available for the viscosity of supercooled water under pressure, in which dramatic anomalies are expected based on interpolation between ambient pressure data for supercooled water and high pressure data for stable water. Here we report measurements with a time-of-flight viscometer down to 244K and up to 300MPa, revealing a reduction of viscosity by pressure by as much as 42%. Inspired by a previous attempt [Tanaka H (2000) J Chem Phys 112:799–809], we show that a remarkably simple extension of a two-state model [Holten V, Sengers JV, Anisimov MA (2014) J Phys Chem Ref Data 43:043101], initially developed to reproduce thermodynamic properties, is able to accurately describe dynamic properties (viscosity, self-diffusion coefficient, and rotational correlation time) as well. Our results support the idea that water is a mixture of a high density, “fragile” liquid, and a low density, “strong” liquid, the varying proportion of which explains the anomalies and fragile-to-strong crossover in water. PMID:28404733

Experimental Investigation of Magnetic Superconducting and other Phase Transitions in Novel f-Electron Materials at Ultra-high Pressures using Designer Diamond Anvils

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

Maple, M. Brian; Jeffries, Jason R.; Ho, Pei-Chun

Pressure is often used as a controlled parameter for the investigation of condensed matter systems. In particular, pressure experiments can provide valuable information into the nature of superconductivity, magnetism, and the coexistence of these two phenomena. Some f-electron, heavy-fermion materials display interesting and novel behavior at moderately low pressures achievable with conventional experimental techniques; however, a growing number of condensed matter systems require ultrahigh pressure techniques, techniques that generate significantly higher pressures than conventional methods, to sufficiently explore their important properties. To that end, we have been funded to develop an ultrahigh pressure diamond anvil cell facility at the Universitymore » of California, San Diego (UCSD) in order to investigate superconductivity, magnetism, non-Fermi liquid behavior, and other phenomena. Our goals for the first year of this grant were as follows: (a) set up and test a suitable refrigerator; (b) set up a laser and spectrometer fluorescence system to determine the pressure within the diamond anvil cell; (c) perform initial resistivity measurements at moderate pressures from room temperature to liquid helium temperatures ({approx}1K); (d) investigate f-electron materials within our current pressure capabilities to find candidate materials for high-pressure studies. During the past year, we have ordered almost all the components required to set up a diamond anvil cell facility at UCSD, we have received and implemented many of the components that have been ordered, we have performed low pressure research on several materials, and we have engaged in a collaborative effort with Sam Weir at Lawrence Livermore National Lab (LLNL) to investigate Au4V under ultrahigh pressure in a designer diamond anvil cell (dDAC). This report serves to highlight the progress we have made towards developing an ultrahigh pressure research facility at UCSD, the research performed in the past year, as well as future directions we plan to pursue.« less

Evaporation rate and vapor pressure of selected polymeric lubricating oils.

NASA Technical Reports Server (NTRS)

Gardos, M. N.

1973-01-01

A recently developed ultrahigh-vacuum quartz spring mass sorption microbalance has been utilized to measure the evaporation rates of several low-volatility polymeric lubricating oils at various temperatures. The evaporation rates are used to calculate the vapor pressures by the Langmuir equation. A method is presented to accurately estimate extended temperature range evaporation rate and vapor pressure data for polymeric oils, incorporating appropriate corrections for the increases in molecular weight and the change in volatility of the progressively evaporating polymer fractions. The logarithms of the calculated data appear to follow linear relationships within the test temperature ranges, when plotted versus 1000/T. These functions and the observed effusion characteristics of the fluids on progressive volatilization are useful in estimating evaporation rate and vapor pressure changes on evaporative depletion.

Development of a low loss magnetic composite utilizing amorphous metal flake. Second semi-annual progress report, March 19-September 18, 1979

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

Not Available

1979-10-01

Composite specimens of amorphous metal flakes have been made using several different binders and several different compaction parameters. The binders have included epoxies, anaerobic adhesives, polyimides, polyamideimides, polyeherimides, and polyesterimides. Compaction variables included the time, temperature and pressure of compaction; flake size, and flake alignment. The best results were achieved using a polyetherimide and aligned flake. Packing factors of 87% were achieved in specimens which also exhibited high mechanical integrity and the ability to withstand a high temperature anneal.

High-level waste program progress report, January 1, 1980-March 31, 1980

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

Not Available

1980-05-01

FUETAP concretes cured at 100/sup 0/C and 0.1 or 0.6 MPa had essentially the same physical properties as those cured at higher temperatures and pressures. Standard specimens containing high concentrations of /sup 244/Cm showed little gasification after 1 month. The large (23-cm ID) spray calciner has been completed and is operating satisfactorily. Construction was completed on a sphere-forming system capable of producing 100-g batches of Synroc spheres by internal gelation, and several runs were made. Preparations for the compatibilty tests are underway. (DLC)

Photometric and spectroscopic gamma-ray observations of solar transient phenomena using long duration balloons

NASA Technical Reports Server (NTRS)

Pelling, M. R.; Duttweiler, F.; Lin, R. F.; Levedahl, W. K.; Primbach, H.; Curtis, D. W.; Burley, K. C.

1985-01-01

A program currently in progress to conduct extended duration spectroscopic and photometric observation of solar X-ray phenomena from balloons is described. High photometric sensitivity to weak hard X-ray bursts is attained using a 600 sq cm array of phoswich scintillators. High spectral resolution for stronger bursts is available from an array of planar germanium detectors. These instruments are carried in a novel balloon gondola dssigned for the 15 to 20 day float durations available through using conventional zero pressure balloons in the radiation controlled (RACOON) mode.

Photometric and spectroscopic gamma-ray observations of solar transient phenomena using long duration balloons

NASA Astrophysics Data System (ADS)

Pelling, M. R.; Duttweiler, F.; Lin, R. F.; Levedahl, W. K.; Primbach, H.; Curtis, D. W.; Burley, K. C.

1985-08-01

A program currently in progress to conduct extended duration spectroscopic and photometric observation of solar X-ray phenomena from balloons is described. High photometric sensitivity to weak hard X-ray bursts is attained using a 600 sq cm array of phoswich scintillators. High spectral resolution for stronger bursts is available from an array of planar germanium detectors. These instruments are carried in a novel balloon gondola dssigned for the 15 to 20 day float durations available through using conventional zero pressure balloons in the radiation controlled (RACOON) mode.

Quantifying real-gas effects on a laminar n-dodecane - air premixed flame

NASA Astrophysics Data System (ADS)

Gopal, Abishek; Yellapantula, Shashank; Larsson, Johan

2015-11-01

With the increasing demand for higher efficiencies in aircraft gas-turbine engines, there has been a progressive march towards high pressure-ratio cycles. Under these conditions, the aviation fuel, Jet A, is injected into the combustor at supercritical pressures. In this work, we study and quantify the effects of transcriticality on a 1D freely propagating laminar n-dodecane - air premixed flame. The impact of the constitutive state relations arising from the Ideal Gas equation of state(EOS) and Peng-Robinson EOS on flame structure and propagation is presented. The effects of real-gas models of transport properties, such as viscosity on laminar flame speed, are also presented.

Project DEEP STEAM

NASA Astrophysics Data System (ADS)

Aeschliman, D. P.; Clay, R. G.; Donaldson, A. B.; Eisenhawer, S. W.; Fox, R. L.; Johnson, D. R.; Mulac, A. J.

1982-01-01

The objective of Project DEEP STEAM is to develop the technology to economically produce heavy oils from deep reservoirs. The tasks included in this project are the development of thermally efficient delivery systems and downhole steam generation systems. During the period January 1-March 31, 1981, effort has continued on a low pressure combustion downhole generator (Rocketdyne), and on two high pressure designs (Foster-Miller Associates, Sandia National Laboratories). The Sandia design was prepared for deployment in the Wilmington Field at Long Beach, California. Progress continued on the Min-Stress II packer concept at L'Garde, Inc., and on the extruded metal packer at Foster-Miller. Initial bare string field data are reported on the insulated tubular test at Lloydminster, Saskatchewan, Canada.

Gut–Brain Axis in Regulation of Blood Pressure

PubMed Central

Yang, Tao; Zubcevic, Jasenka

2017-01-01

Hypertension (HTN) is an escalating health issue worldwide. It is estimated that 1.56 billion people will suffer from high blood pressure (BP) by 2025. Recent studies reported an association between gut dysbiosis and HTN, thus proposing interesting avenues for novel treatments of this condition. The sympathetic nervous system (SNS) and the immune system (IS) play a recognized role in the onset and progression of HTN, while reciprocal communication between gut microbiota and the brain can regulate BP by modulating the interplay between the IS and SNS. This review presents the current state of the science implicating brain-gut connection in HTN, highlighting potential pathways of their interaction in control of BP. PMID:29118721

A Corrosion Risk Assessment Model for Underground Piping

NASA Technical Reports Server (NTRS)

Datta, Koushik; Fraser, Douglas R.

2009-01-01

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

Baroreflex Responses to Acute Changes in Blood Volume in Humans

NASA Technical Reports Server (NTRS)

Thompson, Cynthia A.; Tatro, Dana L.; Ludwig, David A.; Convertino, Victor A.

1990-01-01

To test the hypothesis that acute changes in plasma volume affect the stimulus-response relations of high- and low- pressure baroreflexes, eight men (27-44 yr old) underwent measurements for carotid-cardiac and cardiopulmonary baro-reflex responses under the following three volemic conditions: hypovolemic, normovolemic, and hypervolemic. The stimulus- response relation of the carotid-cardiac response curve was generated using a neck cuff device, which delivered pressure changes between +40 and -65 mmHg in continuous steps of 15 mmHg. The stimulus-response relationship, of the cardio-pulmonary baroreflex were studied by measurements of Forearm Vascular Resistance (FVR) and Peripheral Venous Pressure (PVP) during low levels of lower body negative pressure (O to -20 mmHg). The results indicate greater demand for vasoconstriction for equal reductions in venous pressure during progressive hypovolemia; this condition may compromise the capacity to provide adequate peripheral resistance during severe orthostatic stress. Fluid loading before reentry after spaceflight may act to restore vasoconstrictive capacity of the cardiopulmonary baroreflex but may not be an effective countermeasure against potential post- flight impairment of the carotid-cardiac baroreflex.

Forces and dynamics in epithelial domes of controlled size and shape

NASA Astrophysics Data System (ADS)

Latorre-Ibars, Ernest; Casares, Laura; Gomez-Gonzalez, Manuel; Uroz, Marina; Arroyo, Marino; Trepat, Xavier

Mechanobiology of epithelia plays a central role in morphogenesis, wound healing, and tumor progression. Its current understanding relies on mechanical measurements on flat epithelial layers. However, most epithelia in vivo exhibit a curved 3D shape enclosing a pressurized lumen. Using soft micropatterned substrates we produce massive parallel arrays of epithelial domes with controlled size and basal shape. We measure epithelial traction, tension, and luminal pressure in epithelial domes. The local stress tensor on the freestanding epithelial membrane is then mapped by combining measured luminal pressure and local curvature. We show that tension and cell shape are highly anisotropic and vary along the meridional position of the domes. Finally, we establish constitutive relations between shape, tension, and pressure during perturbations of the contractile machinery, osmotic shocks, and spontaneous fluctuations of dome volume. Our findings contradict a description of the epithelium as a fluid capillary surface. Cells in the dome are unable to relax into a uniform and isotropic tensional state through sub- and supra-cellular rearrangements. Mapping epithelial shape, tension, and pressure will enable quantitative studies of mechanobiology in 3D epithelia of controlled size and shape.

Effects of noradrenaline on human vagal baroreflexes

NASA Technical Reports Server (NTRS)

Airaksinen, K. E.; Huikuri, H. V.; Huhti, L.; Kuusela, T. A.; Tahvanainen, K. U.; Tulppo, M.; Makikallio, T.; Eckberg, D. L.

2001-01-01

BACKGROUND: Baroreflex sensitivity (BRS) is depressed in conditions associated with high sympathetic nerve activity in proportion to circulating noradrenaline (NA) levels. Despite the prognostic importance of measurements of BRS in patients, there is little information on how high NA levels affect arterial baroreflex function. AIM: To understand better the role of NA in cardiovascular homeostasis. METHODS: We gave incremental intravenous NA infusions (at 50 and 100 ng/kg/min) to 12 healthy young men. We measured RR intervals and photoplethysmographic arterial pressures and estimated BRS with cross-spectral and sequence methods during metronome-guided respiration at 0.25 Hz. RESULTS: The high NA infusion rate significantly increased respiratory-frequency (0.15-0.40 Hz) RR interval spectral power and decreased low-frequency (0.04-0.15 Hz) systolic pressure spectral power compared with baseline levels (P < 0.05 for both). Cross-spectral BRS increased from an average (+/- SD) baseline level of 17.3+/-6.6 to 34.1+/-20.8 ms/mmHg at the high NA infusion rate (P < 0.05). Sequence BRS values did not increase significantly during NA infusions. The percentage of sequences with parallel changes in systolic pressures and RR intervals decreased progressively from a baseline level of 16.0+/-12.9 to 10.1+/-7.4 during the low NA infusion rate and to 6.2+/-6.2% during the high rate (P < 0.05 and 0.01, respectively). CONCLUSIONS: Increases in circulating NA to high physiological levels do not depress BRS but interfere with the close baroreflex-mediated coupling that is usually present between arterial pressure and heart rate.

Dynamics of the inlet system of a four-stroke engine

NASA Technical Reports Server (NTRS)

Boden, R H; Schecter, Harry

1944-01-01

Tests were run on a single-cylinder and a multicylinder four-stroke engine in order to determine the effect of the dynamics of the inlet system upon indicated mean effective pressure. Tests on the single-cylinder engine were made at various speeds, inlet valve timings, and inlet pipe lengths. These tests indicated that the indicated mean effective pressure could be raised considerably at any one speed by the use of a suitably long inlet pipe. Tests at other speeds with this length of pipe showed higher indicated mean effective pressure than with a very short pipe, although not so high as could be obtained with the pipe length adjusted for each speed. A general relation was discovered between optimum time of inlet valve closing and pipe length; namely, that longer pipes require later inlet valve closing in order to be fully effective. Tests were also made on three cylinders connected to a single pipe. With this arrangement, increased volumetric efficiency at low speed was obtainable by using a long pipe, but only with a sacrifice of volumetric efficiency at high speed. Volumetric efficiency at high speed was progressively lower as the pipe length was increased.

Results from flamelet and non-flamelet models for supersonic combustion

NASA Astrophysics Data System (ADS)

Ladeinde, Foluso; Li, Wenhai

2017-11-01

Air-breathing propulsion systems (scramjets) have been identified as a viable alternative to rocket engines for improved efficiency. A scramjet engine, which operates at flight Mach numbers around 7 or above, is characterized by the existence of supersonic flow conditions in the combustor. In a dual-mode scramjet, this phenomenon is possible because of the relatively low value of the equivalence ratio and high stagnation temperature, which, together, inhibits thermal choking downstream of transverse injectors. The flamelet method has been our choice for turbulence-combustion interaction modeling and we have extended the basic approach in several dimensions, with a focus on the way the pressure and progress variable are modeled. Improved results have been obtained. We have also examined non-flamelet models, including laminar chemistry (QL), eddy dissipation concept (EDC), and partially-stirred reactor (PaSR). The pressure/progress variable-corrected simulations give better results compared with the original model, with reaction rates that are lower than those from EDC and PaSR. In general, QL tends to over-predict the reaction rate for the supersonic combustion problems investigated in our work.

Automated electronic monitoring of circuit pressures during continuous renal replacement therapy: a technical report.

PubMed

Zhang, Ling; Baldwin, Ian; Zhu, Guijun; Tanaka, Aiko; Bellomo, Rinaldo

2015-03-01

Automated electronic monitoring and analysis of circuit pressures during continuous renal replacement therapy (CRRT) has the potential to predict failure and allow intervention to optimise function. Current CRRT machines can measure and store pressure readings for downloading into databases and for analysis. We developed a procedure to obtain such data at intervals of 1 minute and analyse them using the Prismaflex CRRT machine, and we present an example of such analysis. We obtained data on pressures obtained at intervals of 1 minute in a patient with acute kidney injury and sepsis treated with continuous haemofiltration at 2 L/hour of ultrafiltration and a blood flow of 200 mL/minute. Data analysis identified progressive increases in transmembrane pressure (TMP) and prefilter pressure (PFP) from time 0 until 33 hours or clotting. TMP increased from 104 mmHg to 313 mmHg and PFP increased from from 131 mmHg to 185 mmHg. Effluent pressure showed a progressive increase in the negative pressure applied to achieve ultrafiltration from 0 mmHg to -168 mmHg. The inflection point for such changes was also identified. Blood pathway pressures for access and return remained unchanged throughout. Automated electronic monitoring of circuit pressure during CRRT is possible and provides useful information on the evolution of circuit clotting.

Correlates of aortic stiffness progression in patients with type 2 diabetes: importance of glycemic control: the Rio de Janeiro type 2 diabetes cohort study.

PubMed

Ferreira, Marcel T; Leite, Nathalie C; Cardoso, Claudia R L; Salles, Gil F

2015-05-01

The correlates of serial changes in aortic stiffness in patients with diabetes have never been investigated. We aimed to examine the importance of glycemic control on progression/regression of carotid-femoral pulse wave velocity (cf-PWV) in type 2 diabetes. In a prospective study, two cf-PWV measurements were performed with the Complior equipment in 417 patients with type 2 diabetes over a mean follow-up of 4.2 years. Clinical laboratory data were obtained at baseline and throughout follow-up. Multivariable linear/logistic regressions assessed the independent correlates of changes in cf-PWV. Median cf-PWV increase was 0.11 m/s per year (1.1% per year). Overall, 212 patients (51%) increased/persisted with high cf-PWV, while 205 (49%) reduced/persisted with low cf-PWV. Multivariate linear regression demonstrated direct associations between cf-PWV changes and mean HbA1c during follow-up (partial correlation 0.14, P = 0.005). On logistic regression, a mean HbA1c ≥7.5% (58 mmol/mol) was associated with twofold higher odds of having increased/persistently high cf-PWV during follow-up. Furthermore, the rate of HbA1c reduction relative to baseline levels was inversely associated with cf-PWV changes (partial correlation -0.11, P = 0.011) and associated with reduced risk of having increased/persistently high aortic stiffness (odds ratio 0.82 [95% CI 0.69-0.96]; P = 0.017). Other independent correlates of progression in aortic stiffness were increases in systolic blood pressure and heart rate between the two cf-PWV measurements, older age, female sex, and presence of dyslipidemia and retinopathy. Better glycemic control, together with reductions in blood pressure and heart rate, was the most important correlate to attenuate/prevent progression of aortic stiffness in patients with type 2 diabetes. © 2015 by the American Diabetes Association. Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered.

Time-resolved Small Angle X-ray Scattering During the Formation of Detonation Nano-Carbon Condensates

NASA Astrophysics Data System (ADS)

Bagge-Hansen, Michael; Hammons, Josh; Nielsen, Mike; Lauderbach, Lisa; Hodgin, Ralph; Bastea, Sorin; van Buuren, Tony; Pagoria, Phil; May, Chadd; Jensen, Brian; Gustavsen, Rick; Watkins, Erik; Firestone, Millie; Dattelbaum, Dana; Fried, Larry; Cowan, Matt; Willey, Trevor

2017-06-01

Carbon nanomaterials are spontaneously generated under high pressure and temperature conditions present during the detonation of many high explosive (HE) materials. Thermochemical modeling suggests that the phase, size, and morphology of carbon condensates are strongly dependent on the type of HE used and associated evolution of temperature and pressure during the very early stages of detonation. Experimental validation of carbon condensation under these extreme conditions has been technically challenging. Here, we present synchrotron-based, time-resolved small-angle x-ray scattering (TR-SAXS) measurements collected during HE detonations, acquired from discrete sub-100 ps x-ray pulses, every 153.4 ns. We select from various HE materials and geometries to explore a range of achievable pressures and temperatures that span detonation conditions and, correspondingly, generate an array of nano-carbon products, including nano-diamonds and nano-onions. The TR-SAXS patterns evolve rapidly over the first few hundred nanoseconds. Comparing the results with modeling offers significant progress towards a general carbon equation of state. Prepared by LLNL under Contract DE-AC52-07NA27344.

Preliminary Results of Solid Gas Generator Micropropulsion

NASA Technical Reports Server (NTRS)

deGroot, Wilhelmus A.; Reed, Brian D.; Brenizer, Marshall

1999-01-01

A decomposing solid thruster concept, which creates a more benign thermal and chemical environment than solid propellant combustion, while maintaining, performance similar to solid combustion, is described. A Micro-Electro-Mechanical (MEMS) thruster concept with diode laser and fiber-optic initiation is proposed, and thruster components fabricated with MEMS technology are presented. A high nitrogen content solid gas generator compound is evaluated and tested in a conventional axisymmetric thrust chamber with nozzle throat area ratio of 100. Results show incomplete decomposition of this compound in both low pressure (1 kPa) and high pressure (1 MPa) environments, with decomposition of up to 80% of the original mass. Chamber pressures of 1.1 MPa were obtained, with maximum calculated thrust of approximately 2.7 N. Resistively heated wires and resistively heated walls were used to initiate decomposition. Initiation tests using available lasers were unsuccessful, but infrared spectra of the compound show that the laser initiation tests used inappropriate wavelengths for optimal propellant absorption. Optimal wavelengths for laser ignition were identified. Data presented are from tests currently in progress. Alternative solid gas generator compounds are being evaluated for future tests.

Efficiency Considerations in Low Pressure Turbines

NASA Technical Reports Server (NTRS)

2010-01-01

Issues & Topics Discussed: a) Aviation Week reported shortfall In LPT efficiency due to the application of "high lift airfoils". b) Progress in the design technologies in LPTs during the last 20 years: 1) Application of RANS based CFD codes. 2) Integration of recent experimental data and modeling of LPT airfoil specific flows into design methods. c) Opportunities to further enhance LPT efficiency for commercial aviation and military transport application and to impact emissions, noise, weight & cost.

Effectiveness of Preacclimatization Strategies for High-Altitude Exposure

DTIC Science & Technology

2013-01-01

pulse oximeter (Model 8600, Nonin Medical, Inc., Plymouth, MN). Ventilatory assessments were conducted repeatedly during all phases of each study...progressive rise in arterial oxygen saturation (Sa02, mean ± SE) for 37 men (21) and 22 women (20) while living on the summit of Pikes Peak (4300 m). Men...almost immediately with altitude exposure to compensate for the lower partial pressure of oxygen (P02 ). Nevertheless, the first few days of

High pressure cosmochemistry applied to major planetary interiors: Experimental studies. [phase diagram for the ammonia water system

NASA Technical Reports Server (NTRS)

Nicol, M. F.; Johnson, M.; Schwake, A.

1983-01-01

Progress is reported in the development of the P-T-X diagram for 0 less than or = X less than or = 0.50 and in the development of techniques for measuring adiabats of phases of NH3-H2O. The partial phase diagram is presented, investigations of the compositions of ammonia ices are described, and methods for obtaining the infrared spectra of ices are discussed.

Use of volume-targeted non-invasive bilevel positive airway pressure ventilation in a patient with amyotrophic lateral sclerosis*,**

PubMed Central

Diaz-Abad, Montserrat; Brown, John Edward

2014-01-01

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease in which most patients die of respiratory failure. Although volume-targeted non-invasive bilevel positive airway pressure (BPAP) ventilation has been studied in patients with chronic respiratory failure of various etiologies, its use in ALS has not been reported. We present the case of a 66-year-old woman with ALS and respiratory failure treated with volume-targeted BPAP ventilation for 15 weeks. Weekly data downloads showed that disease progression was associated with increased respiratory muscle weakness, decreased spontaneous breathing, and increased use of non-invasive positive pressure ventilation, whereas tidal volume and minute ventilation remained relatively constant. PMID:25210968

Damage Tolerance of Large Shell Structures

NASA Technical Reports Server (NTRS)

Minnetyan, L.; Chamis, C. C.

1999-01-01

Progressive damage and fracture of large shell structures is investigated. A computer model is used for the assessment of structural response, progressive fracture resistance, and defect/damage tolerance characteristics. Critical locations of a stiffened conical shell segment are identified. Defective and defect-free computer models are simulated to evaluate structural damage/defect tolerance. Safe pressurization levels are assessed for the retention of structural integrity at the presence of damage/ defects. Damage initiation, growth, accumulation, and propagation to fracture are included in the simulations. Damage propagation and burst pressures for defective and defect-free shells are compared to evaluate damage tolerance. Design implications with regard to defect and damage tolerance of a large steel pressure vessel are examined.

A model to calculate the progression of the centre of pressure under the foot during gait analysis.

PubMed

Louey, Melissa Gar Yee; Mudge, Anita; Wojciechowski, Elizabeth; Sangeux, Morgan

2017-09-01

Pedobarography and the centre of pressure (COP) progression is useful to understand foot function. Pedobarography is often unavailable in gait laboratories or completed asynchronously to kinematic and kinetic data collection. This paper presents a model that allows calculation of COP progression synchronously using force plate data. The model is an adjunct to Plug-In-Gait and was applied to 49 typically developing children to create reference COP data. COP progressions were noted to spend 8% of stance behind the ankle joint centre, traverse lateral of the longitudinal axis of the foot through the midfoot for 76% of stance and finishing past the second metatarsal head on the medial side for 16% of stance. It is hoped the model will bridge the information gap for gait laboratories lacking pedobarography during foot assessments and will open up the possibility of retrospective research into COP progression based indices on kinematic data. Copyright © 2017 Elsevier B.V. All rights reserved.

Determinants of spring migration departure decision in a bat.

PubMed

Dechmann, Dina K N; Wikelski, M; Ellis-Soto, D; Safi, K; O'Mara, M Teague

2017-09-01

Migratory decisions in birds are closely tied to environmental cues and fat stores, but it remains unknown if the same variables trigger bat migration. To learn more about the rare phenomenon of bat migration, we studied departure decisions of female common noctules ( Nyctalus noctula ) in southern Germany. We did not find the fattening period that modulates departure decisions in birds. Female noctules departed after a regular evening foraging session, uniformly heading northeast. As the day of year increased, migratory decisions were based on the interactions among wind speed, wind direction and air pressure. As the migration season progressed, bats were likely to migrate on nights with higher air pressure and faster tail winds in the direction of travel, and also show high probability of migration on low-pressure nights with slow head winds. Common noctules thus monitor complex environmental conditions to find the optimal migration night. © 2017 The Authors.

Spontaneous deswelling of pNIPAM microgels at high concentrations

NASA Astrophysics Data System (ADS)

Gasser, Urs; Scotti, Andrea; Herman, Emily S.; Pelaez-Fernandez, Miguel; Han, Jun; Menzel, Andreas; Lyon, L. Andrew; Fernandez-Nieves, Alberto

Polydisperse suspensions of pNIPAM microgel particles show a unique, spontaneous particle deswelling behavior. Beyond a critical concentration, the largest microgels deswell and thereby reduce the polydispersity of the suspension. We have recently unraveled the mechanism of this spontaneous, selective deswelling. pNIPAM microgels carry charged sulfate groups originating from the ammonium persulfate starter used in particle synthesis. Most of the ammonium counterions are trapped close to the microgel surface, but a fraction of them escapes the electrostatic attraction and contributes to the osmotic pressure of the suspension. The counterion clouds of neighboring particles progressively overlap with increasing volume fraction, leading to an increase of free counterions and the osmotic pressure outside but not inside the microgel particles. We find particles to deswell when the resulting osmotic pressure difference between the inside and the outside becomes larger their bulk modulus. For pNIPAM microgels synthesized with the same protocol, the largest particles are the softest and deswell first.

[Non-pharmacologic treatment of arterial hypertension in hemodialysis patients].

PubMed

Chazot, C; Charra, B

2007-10-01

High blood pressure in dialysis patients is related to extracellular volume excess and the related increase of systemic vascular resistances. Scribner has early described the treatment of hypertension with ultrafiltration and low salt diet, without any drugs. The dry weight method relies on the progressive reduction of the postdialysis body weight until blood pressure is normalized. Additional measures are needed such as low salt diet, neutral sodium balance during dialysis treatment, stop of antihypertensive drugs, adequate length of the dialysis session, and patient education. It may exist a lag time between the normalization of the extracellular volume and blood pressure. It is related to the correction of the hemodynamic consequences of the extracellular volume overload. Moreover, the dry weight may potentially vary in patients undergoing catabolic intercurrent events. The complications of these changes (severe hypertension, pulmonary oedema) must be anticipated by the nephrologist and the staff to avoid additional morbidity to the patient.

Measuring Pressure Volume Loops in the Mouse.

PubMed

Townsend, DeWayne

2016-05-02

Understanding the causes and progression of heart disease presents a significant challenge to the biomedical community. The genetic flexibility of the mouse provides great potential to explore cardiac function at the molecular level. The mouse's small size does present some challenges in regards to performing detailed cardiac phenotyping. Miniaturization and other advancements in technology have made many methods of cardiac assessment possible in the mouse. Of these, the simultaneous collection of pressure and volume data provides a detailed picture of cardiac function that is not available through any other modality. Here a detailed procedure for the collection of pressure-volume loop data is described. Included is a discussion of the principles underlying the measurements and the potential sources of error. Anesthetic management and surgical approaches are discussed in great detail as they are both critical to obtaining high quality hemodynamic measurements. The principles of hemodynamic protocol development and relevant aspects of data analysis are also addressed.

Abnormal pressure study in the Malay and Penyu Basins: A regional understanding

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

Kader, M.S.; Leslie, W.

1994-07-01

A majority of wells drilled in the Malay and Penyu basins were terminated due to abnormal pressure. Blowouts and the subsequent loss of technical data have always been a concern during drilling operations. This study employs data from 94 exploratory wells spread throughout the Malay and Penyu basins. The postdrill abnormal pressure predictive method used is pressure vs. depth plots of data obtained from Repeat Formation tester (RFT) readings. The study results indicate that abnormal pressure occurs in a progressively older stratigraphic unit toward the basin margins. The margins of the Malay and the entire Penyu basins tend to bemore » normally pressured. The onset of abnormal pressure appears to be abrupt in the northern portion and more gradual in the southern part of the Malay Basin. Abnormal pressure in the Malay Basin is found to be neither depth dependent nor age related. Many factors can cause the abnormal formation pressures. In some areas, a combination of factors prevails. Rapid deposition of the middle to late Miocene siliciclastic sediments appears to be a dominant cause particularly in the center of the Malay Basin. A low sand:shale ratio coupled with a high geothermal gradient is also found to be a local cause near the axis of the basin. This phenomenon is crucial to the understanding of hydrocarbon migration and will enable the planning of safe and efficient drilling campaigns.« less

Molecular Tagging Velocimetry Development for In-situ Measurement in High-Temperature Test Facility

NASA Technical Reports Server (NTRS)

Andre, Matthieu A.; Bardet, Philippe M.; Burns, Ross A.; Danehy, Paul M.

2015-01-01

The High Temperature Test Facility, HTTF, at Oregon State University (OSU) is an integral-effect test facility designed to model the behavior of a Very High Temperature Gas Reactor (VHTR) during a Depressurized Conduction Cooldown (DCC) event. It also has the ability to conduct limited investigations into the progression of a Pressurized Conduction Cooldown (PCC) event in addition to phenomena occurring during normal operations. Both of these phenomena will be studied with in-situ velocity field measurements. Experimental measurements of velocity are critical to provide proper boundary conditions to validate CFD codes, as well as developing correlations for system level codes, such as RELAP5 (http://www4vip.inl.gov/relap5/). Such data will be the first acquired in the HTTF and will introduce a diagnostic with numerous other applications to the field of nuclear thermal hydraulics. A laser-based optical diagnostic under development at The George Washington University (GWU) is presented; the technique is demonstrated with velocity data obtained in ambient temperature air, and adaptation to high-pressure, high-temperature flow is discussed.

Advanced performance of small diaphragm vacuum pumps through the use of mechatronics

NASA Astrophysics Data System (ADS)

Lachenmann, R.; Dirscherl, J.

Oil-free diaphragm vacuum pumps have proven to be the best way in vacuum generation for the chemical laboratory and they also find increasing use as backing pumps for modern wide-range turbo molecular pumps. The majority of vacuum pumps in practical use pump only a rather small percentage of their lifetime at full gas load. A pump backing a turbo molecular pump does not have to pump a significant gas load when the high-vacuum pump is running at ultimate vacuum pressure. Also, for a vacuum distillation the vacuum pump has to operate at full speed only at the beginning to lower the pressure inside the system to a vacuum level where evaporation starts. In a rather leak-tight system the distillation process continues by evaporating from the hot liquid and condensing at the cold condenser without the need of a mechanical vacuum pump. Rotational speed controlled diaphragm pumps are now available through progress in mechatronics and offer high pumping speed capability for fast pump-down cycles and precise pressure control for distillations. At low gas load the rotational speed can be reduced, improving maintenance intervals, power consumption, noise, vibration and - surprisingly - also ultimate pressure. The different behaviour in pumping speed and ultimate pressure of rotational speed controlled diaphragm pumps in comparison to constant-speed pumps is related to the mechanical properties of the valves and gas dynamics .

Passive flow regulators for drug delivery and hydrocephalus treatment

NASA Astrophysics Data System (ADS)

Chappel, E.; Dumont-Fillon, D.; Mefti, S.

2014-03-01

Passive flow regulators are usually intended to deliver or drain a fluid at a constant rate independently from pressure variations. New designs of passive flow regulators made of a stack of a silicon membrane anodically bonded to a Pyrex substrate are proposed. A first design has been built for the derivation of cerebrospinal fluid (CSF) towards peritoneum for hydrocephalus treatment. The device allows draining CSF at the patient production rate independently from postural changes. The flow rate is regulated at 20 ml/h in the range 10 to 40 mbar. Specific features to adjust in vivo the nominal flow rate are shown. A second design including high pressure shut-off feature has been made. The intended use is drug delivery with pressurized reservoir of typically 100 to 300 mbar. In both cases, the membrane comprises several holes facing pillars in the Pyrex substrate. These pillars are machined in a cavity which ensures a gap between the membrane and the pillars at rest. The fluid in the pressurized reservoir is directly in contact with the top surface of the membrane, inducing its deflection towards Pyrex substrate and closing progressively the fluidic pathway through each hole of the membrane. Since the membrane deflection is highly non-linear, FEM simulations have been performed to determine both radial position and diameter of the membrane holes that ensure a constant flow rate for a given range of pressure.

Blood pressure, hypertension, RAAS blockade, and drug therapy in diabetic kidney disease.

PubMed

Yamout, Hala; Lazich, Ivana; Bakris, George L

2014-05-01

Type 2 diabetes is the most common cause of CKD and ESRD in the United States and the Western world. Hypertension is prevalent in this cohort, and control of blood pressure is perhaps the most important risk factor to reduce CKD progression. The most recent blood pressure target recommended by the Kidney Disease: Improving Global Outcomes and Kidney Disease Outcomes Quality Initiative guideline committees is less than 140/90 mmHg for all patients with CKD. There is some evidence for those with 1 g or more of albuminuria, albeit weak, to support a blood pressure target of less than 130/80 mmHg. Multiple studies demonstrate that renin-angiotensin-aldosterone system (RAAS) blockers are important in reducing cardiovascular risk and progression of CKD in those with advanced proteinuric nephropathy. However, there is no evidence that they prevent nephropathy or that reduction in microalbuminuria alone is associated with slowed nephropathy progression. The purpose of this article is to review the major studies that have evaluated cardiovascular and kidney endpoints in patients with diabetes and the role of RAAS blockers in the treatment of this disease. Copyright © 2014 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.

Design and development of a prototype wet oxidation system for the reclamation of water and the disposition of waste residues onboard space vehicles

NASA Technical Reports Server (NTRS)

Jagow, R. B.

1972-01-01

Laboratory investigations to define optimum process conditions for oxidation of fecal/urine slurries were conducted in a one-liter batch reactor. The results of these tests formed the basis for the design, fabrication, and testing of an initial prototype system, including a 100-hour design verification test. Areas of further development were identified during this test. Development of a high pressure slurry pump, materials corrosion studies, oxygen supply trade studies, comparison of salt removal water recovery devices, ammonia removal investigation, development of a solids grinder, reactor design studies and bearing life tests, and development of shutoff valves and a back pressure regulator were undertaken. The development work has progressed to the point where a prototype system suitable for manned chamber testing can be fabricated and tested with a high degree of confidence of success.

DNS of High Pressure Supercritical Combustion

NASA Astrophysics Data System (ADS)

Chong, Shao Teng; Raman, Venkatramanan

2016-11-01

Supercritical flows have always been important to rocket motors, and more recently to aircraft engines and stationary gas turbines. The purpose of the present study is to understand effects of differential diffusion on reacting scalars using supercritical isotropic turbulence. Focus is on fuel and oxidant reacting in the transcritical region where density, heat capacity and transport properties are highly sensitive to variations in temperature and pressure. Reynolds and Damkohler number vary as a result and although it is common to neglect differential diffusion effects if Re is sufficiently large, this large variation in temperature with heat release can accentuate molecular transport differences. Direct numerical simulations (DNS) for one step chemistry reaction between fuel and oxidizer are used to examine the differential diffusion effects. A key issue investigated in this paper is if the flamelet progress variable approach, where the Lewis number is usually assumed to be unity and constant for all species, can be accurately applied to simulate supercritical combustion.

A method for measuring the local gas pressure within a gas-flow stage in situ in the transmission electron microscope

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

Colby, Robert J.; Alsem, Daan H.; Liyu, Andrey V.

2015-06-01

The development of environmental transmission electron microscopy (TEM) has enabled in situ experiments in a gaseous environment with high resolution imaging and spectroscopy. Addressing scientific challenges in areas such as catalysis, corrosion, and geochemistry can require pressures much higher than the ~20 mbar achievable with a differentially pumped, dedicated environmental TEM. Gas flow stages, in which the environment is contained between two semi-transparent thin membrane windows, have been demonstrated at pressures of several atmospheres. While this constitutes significant progress towards operando measurements, the design of many current gas flow stages is such that the pressure at the sample cannot necessarilymore » be directly inferred from the pressure differential across the system. Small differences in the setup and design of the gas flow stage can lead to very different sample pressures. We demonstrate a method for measuring the gas pressure directly, using a combination of electron energy loss spectroscopy and TEM imaging. This method requires only two energy filtered TEM images, limiting the measurement time to a few seconds and can be performed during an ongoing experiment at the region of interest. This approach provides a means to ensure reproducibility between different experiments, and even between very differently designed gas flow stages.« less

An Universal packaging technique for low-drift implantable pressure sensors.

PubMed

Kim, Albert; Powell, Charles R; Ziaie, Babak

2016-04-01

Monitoring bodily pressures provide valuable diagnostic and prognostic information. In particular, long-term measurement through implantable sensors is highly desirable in situations where percutaneous access can be complicated or dangerous (e.g., intracranial pressure in hydrocephalic patients). In spite of decades of progress in the fabrication of miniature solid-state pressure sensors, sensor drift has so far severely limited their application in implantable systems. In this paper, we report on a universal packaging technique for reducing the sensor drift. The described method isolates the pressure sensor from a major source of drift, i.e., contact with the aqueous surrounding environment, by encasing the sensor in a silicone-filled medical-grade polyurethane balloon. In-vitro soak tests for 100 days using commercial micromachined piezoresistive pressure sensors demonstrate a stable operation with the output remaining within 1.8 cmH2O (1.3 mmHg) of a reference pressure transducer. Under similar test conditions, a non-isolated sensor fluctuates between 10 and 20 cmH2O (7.4-14.7 mmHg) of the reference, without ever settling to a stable operation regime. Implantation in Ossabow pigs demonstrate the robustness of the package and its in-vivo efficacy in reducing the baseline drift.

US Army Institute of Surgical Research Annual Research Progress Report for Fiscal Year 1987.

DTIC Science & Technology

1987-10-01

oases, respiratory rate, chest roentgenograms), cardiovascular (blood pressure, central venous pressure, cardiac output), and renal (urine output, urine...Monitoring includes the precordial and/or esophageal stethoscope, peripheral pulse, blood pressure, central venous pressure, Swan-Ganz catheter... central venous , peripheral venous , and Swan-Ganz (7F, American Edward Laboratories, Irvine CA) catheters and an esophageal balloon were inserted. After a 2

The impact of gastric distension on the lower esophageal sphincter and its exposure to acid gastric juice.

PubMed

Ayazi, Shahin; Tamhankar, Anand; DeMeester, Steven R; Zehetner, Joerg; Wu, Calvin; Lipham, John C; Hagen, Jeffrey A; DeMeester, Tom R

2010-07-01

The lower esophageal sphincter (LES) in patients with gastroesophageal reflux disease often has a low resting pressure and a short abdominal length. The mechanism by which this occurs is unknown. We hypothesize that gastric distension causes progressive effacement of the abdominal portion of the LES, exposing it to acid injury resulting in mucosal and sphincter damage. Our aim was to assess in normal subjects the effect of gastric distension on the LES length and pressure and its exposure to acid gastric juice. Eleven asymptomatic volunteers had their LES length and pressure measured before and during gastric distension. The location of the pH step-up point (shift from gastric pH to a pH >4) was also measured before and after distension. Progressive gastric distension with air resulted in progressive shortening of LES (R = 0.89, P < 0.0001). After infusion of 750 cc of air there was a significant reduction in the median LES length from 4 to 2.6 cm (P = 0.001). This change occurred in the abdominal length of the LES (2.6-1.4 cm [P = 0.001]) and not in the thoracic length. At rest the pH step-up point was 0.5 cm above the lower border of the LES and with distension moved a median of 1 cm cephalad within the LES. Simultaneously with the loss of length there was a reduction in LES pressure (27.4-23.4 mm Hg, P = 0.02). Gastric distension causes progressive shortening of the abdominal length of the LES and a reduction in its pressure. The process exposes the effaced mucosa and sphincter to acid gastric juice.

A fuzzy logic expert system for evaluating policy progress towards sustainability goals.

PubMed

Cisneros-Montemayor, Andrés M; Singh, Gerald G; Cheung, William W L

2017-12-16

Evaluating progress towards environmental sustainability goals can be difficult due to a lack of measurable benchmarks and insufficient or uncertain data. Marine settings are particularly challenging, as stakeholders and objectives tend to be less well defined and ecosystem components have high natural variability and are difficult to observe directly. Fuzzy logic expert systems are useful analytical frameworks to evaluate such systems, and we develop such a model here to formally evaluate progress towards sustainability targets based on diverse sets of indicators. Evaluation criteria include recent (since policy enactment) and historical (from earliest known state) change, type of indicators (state, benefit, pressure, response), time span and spatial scope, and the suitability of an indicator in reflecting progress toward a specific objective. A key aspect of the framework is that all assumptions are transparent and modifiable to fit different social and ecological contexts. We test the method by evaluating progress towards four Aichi Biodiversity Targets in Canadian oceans, including quantitative progress scores, information gaps, and the sensitivity of results to model and data assumptions. For Canadian marine systems, national protection plans and biodiversity awareness show good progress, but species and ecosystem states overall do not show strong improvement. Well-defined goals are vital for successful policy implementation, as ambiguity allows for conflicting potential indicators, which in natural systems increases uncertainty in progress evaluations. Importantly, our framework can be easily adapted to assess progress towards policy goals with different themes, globally or in specific regions.

Seal Technology Development for Advanced Component for Airbreathing Engines

NASA Technical Reports Server (NTRS)

Snyder, Philip H.

2008-01-01

Key aspects of the design of sealing systems for On Rotor Combustion/Wave Rotor (ORC/WR) systems were addressed. ORC/WR systems generally fit within a broad class of pressure gain Constant Volume Combustors (CVCs) or Pulse Detonation Combustors (PDCs) which are currently being considered for use in many classes of turbine engines for dramatic efficiency improvement. Technology readiness level of this ORC/WR approaches are presently at 2.0. The results of detailed modeling of an ORC/WR system as applied to a regional jet engine application were shown to capture a high degree of pressure gain capabilities. The results of engine cycle analysis indicated the level of specific fuel consumption (SFC) benefits to be 17 percent. The potential losses in pressure gain due to leakage were found to be closely coupled to the wave processes at the rotor endpoints of the ORC/WR system. Extensive investigation into the sealing approaches is reported. Sensitivity studies show that SFC gains of 10 percent remain available even when pressure gain levels are highly penalized. This indicates ORC/WR systems to have a high degree of tolerance to rotor leakage effects but also emphasizes their importance. An engine demonstration of an ORC/WR system is seen as key to progressing the TRL of this technology. An industrial engine was judged to be a highly advantageous platform for demonstration of a first generation ORC/WR system. Prior to such a demonstration, the existing NASA pressure exchanger wave rotor rig was identified as an opportunity to apply both expanded analytical modeling capabilities developed within this program and to identify and fix identified leakage issues existing within this rig. Extensive leakage analysis of the rig was performed and a detailed design of additional sealing strategies for this rig was generated.

Risk factors for predicting visual field progression in Chinese patients with primary open-angle glaucoma: A retrospective study.

PubMed

Hung, Kuo-Hsuan; Cheng, Ching-Yu; Liu, Catherine Jui-Ling

2015-07-01

Glaucoma is a leading cause of irreversible blindness worldwide. It is characterized by progressive deterioration of the visual field (VF) that results in a complete loss of vision. This study aimed to determine the risk factors associated with VF progression in Chinese patients with primary open-angle glaucoma (POAG). We reviewed the charts of POAG patients who visited our clinic between July 2009 and June 2010. We included patients with five or more reliable VF tests using the Humphrey Field Analyzer (Humphrey Instruments, San Leandro, CA, USA) during a period of at least 2 years. The scoring system of the Collaborative Initial Glaucoma Treatment Study (CIGTS) was used to code the VF. Progression was defined as an increasing score ≥3, compared to the averaged baseline data. Univariate and multivariate logistic regression analyses were performed to identify the risk factors of VF progression. There were 92 patients (representing 92 eyes) with an average of 8.9 reliable VFs over a mean follow up of 5.4 years. Multivariate logistic regression showed that eyes with more VF tests [odds ratio (OR) = 1.500, p < 0.010] and either increased peak intraocular pressure (IOP) (OR = 1.235, p = 0.044) or a wide IOP range (OR = 1.165, p = 0.041) favored VF progression. High myopia (less than -6.0 D) was not a risk factor (OR = 1.289, p = 0.698) for VF progression in this study. In addition to a greater number of VF tests, Chinese patients with treated POAG who experienced a high peak IOP or a wide range of IOP during follow up were more likely to have VF deterioration. Copyright © 2015. Published by Elsevier Taiwan.

The performance of a centrifugal compressor with high inlet prewhirl

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

Whitfield, A.; Abdullah, A.H.

1998-07-01

The performance requirements of centrifugal compressors usually include a broad operating range between surge and choke. This becomes increasingly difficult to achieve as increased pressure ratio is demanded. In order to suppress the tendency to surge and extend the operating range at low flow rates, inlet swirl is often considered through the application of inlet guide vanes. To generate high inlet swirl angles efficiently, an inlet volute has been applied as the swirl generator, and a variable geometry design developed in order to provide zero swirl. The variable geometry approach can be applied to increase the swirl progressively or tomore » switch rapidly from zero swirl to maximum swirl. The variable geometry volute and the swirl conditions generated are described. The performance of a small centrifugal compressor is presented for a wide range of inlet swirl angles. In addition to the basic performance characteristics of the compressor, the onsets of flow reversals at impeller inlet are presented, together with the development of pressure pulsations, in the inlet and discharge ducts, through to full surge. The flow rate at which surge occurred was shown, by the shift of the peak pressure condition and by the measurement of the pressure pulsations, to be reduced by over 40%.« less

Mechanical specific energy versus depth of cut in rock cutting and drilling

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

Zhou, Yaneng; Zhang, Wu; Gamwo, Isaac

The relationship between Mechanical Specific Energy (MSE) and the Rate of Penetration (ROP), or equivalently the depth of cut per revolution, provides an important measure for strategizing a drilling operation. This study explores how MSE evolves with depth of cut, and presents a concerted effort that encompasses analytical, computational and experimental approaches. A simple model for the relationship between MSE and cutting depth is first derived with consideration of the wear progression of a circular cutter. This is an extension of Detournay and Defourny's phenomenological cutting model. Wear is modeled as a flat contact area at the bottom of amore » cutter referred to as a wear flat, and that wear flat in the past is often considered to be fixed during cutting. But during a drilling operation by a full bit that consists of multiple circular cutters, the wear flat length may increase because of various wear mechanisms involved. The wear progression of cutters generally results in reduced efficiency with either increased MSE or decreased ROP. Also, an accurate estimate of removed rock volume is found important for the evaluation of MSE. The derived model is compared with experiment results from a single circular cutter, for cutting soft rock under ambient pressure with actual depth measured through a micrometer, and for cutting high strength rock under high pressure with actual cutting area measured by a confocal microscope. Lastly, the model is employed to interpret the evolution of MSE with depth of cut for a full drilling bit under confining pressure. The general form of equation of the developed model is found to describe well the experiment data and can be applied to interpret the drilling data for a full bit.« less

Mechanical specific energy versus depth of cut in rock cutting and drilling

DOE PAGES

Zhou, Yaneng; Zhang, Wu; Gamwo, Isaac; ...

2017-12-07

The relationship between Mechanical Specific Energy (MSE) and the Rate of Penetration (ROP), or equivalently the depth of cut per revolution, provides an important measure for strategizing a drilling operation. This study explores how MSE evolves with depth of cut, and presents a concerted effort that encompasses analytical, computational and experimental approaches. A simple model for the relationship between MSE and cutting depth is first derived with consideration of the wear progression of a circular cutter. This is an extension of Detournay and Defourny's phenomenological cutting model. Wear is modeled as a flat contact area at the bottom of amore » cutter referred to as a wear flat, and that wear flat in the past is often considered to be fixed during cutting. But during a drilling operation by a full bit that consists of multiple circular cutters, the wear flat length may increase because of various wear mechanisms involved. The wear progression of cutters generally results in reduced efficiency with either increased MSE or decreased ROP. Also, an accurate estimate of removed rock volume is found important for the evaluation of MSE. The derived model is compared with experiment results from a single circular cutter, for cutting soft rock under ambient pressure with actual depth measured through a micrometer, and for cutting high strength rock under high pressure with actual cutting area measured by a confocal microscope. Lastly, the model is employed to interpret the evolution of MSE with depth of cut for a full drilling bit under confining pressure. The general form of equation of the developed model is found to describe well the experiment data and can be applied to interpret the drilling data for a full bit.« less

The nature, distribution and genesis of the coesite and stishovite associated with the pseudotachylite of the Vredefort Dome, South Africa

NASA Astrophysics Data System (ADS)

Martini, J. E. J.

1991-04-01

The Vredefort Dome represents the uplift centre of a well known 2.00 Ga old impact structure of unusually large magnitude. Shock features like shatter cones, planar features and high-pressure silica polymorphs are common. The present study deals with the description, mode of occurrence, field distribution and post-shock metamorphic alteration of coesite and stishovite which were poorly documented up to now. These minerals occur as unusually large crystals in the quartzite of the wall rock in contact with very thin pseudotachylite veins. In the pseudotachylite itself, which can be interpreted as a friction and/or a shock recovery melt, fine needles of kyanite are ubiquitous. It is proposed that these thin pseudotachylites (A-type) formed during the transit of the shock wave. They preceded the development of thick pseudotachylite and microbreccia veins (B-type) which formed during the tensional period which immediately followed. From comparison with the model of formation of high-pressure polymorphs in porous sandstone, it is suggested that higher pressure and stress was concentrated along the A-type veins at the arrival of the shock front. At this time the quartz was transformed into a "high-pressure phase" which was probably poorly crystalline. Behind the shock front, that is during the rarefaction, the pressure was progressively released and the polymorphs crystallized from this initial "high-pressure phase". Stishovite crystallized first, followed by coesite. The high-pressure conditions may have lasted an unusually long time due to the magnitude of the Vredefort impact. This long time, probably about one second, may account for the large size of the coesite and stishovite crystals. Most of the high-pressure silica polymorphs are corroded to a variable degree by secondary quartz and preserved only in a restricted area of the impact structure. This alteration is attributed to post-shock metamorphism due to the temperature of the rock before impact plus the heat left after shock recovery. Some of the evidence put forward by authors against the impact model is discussed according to the facts arising from this investigation. It is concluded that an origin by impact remains the simplest and most realistic model to explain the origin of the Vredefort Dome.

Optical fiber sensors for high temperature harsh environment applications

NASA Astrophysics Data System (ADS)

Xiao, Hai; Wei, Tao; Lan, Xinwei; Zhang, Yinan; Duan, Hongbiao; Han, Yukun; Tsai, Hai-Lung

2010-04-01

This paper summarizes our recent research progresses in developing optical fiber harsh environment sensors for various high temperature harsh environment sensing applications such as monitoring of the operating conditions in a coal-fired power plant and in-situ detection of key gas components in coal-derived syngas. The sensors described in this paper include a miniaturized inline fiber Fabry-Perot interferometer (FPI) fabricated by one-step fs laser micromachining, a long period fiber grating (LPFG) and a fiber inline core-cladding mode interferometer (CMMI) fabricated by controlled CO2 laser irradiations. Their operating principles, fabrication methods, and applications for measurement of various physical and chemical parameters in a high temperature and high pressure coexisting harsh environment are presented.

Exploration of Venus' Deep Atmosphere and Surface Environment

NASA Technical Reports Server (NTRS)

Glaze, L. S.; Amato, M.; Garvin, J. B.; Johnson, N. M.

2017-01-01

Venus formed in the same part of our solar system as Earth, apparently from similar materials. Although both planets are about the same size, their differences are profound. Venus and Earth experienced vastly different evolutionary pathways resulting in unexplained differences in atmospheric composition and dynamics, as well as in geophysical processes of the planetary surfaces and interiors. Understanding when and why the evolutionary pathways of Venus and Earth diverged is key to understanding how terrestrial planets form and how their atmospheres and surfaces evolve. Measurements made in situ, within the near-surface or surface environment, are critical to addressing unanswered questions. We have made substantial progress modernizing and maturing pressure vessel technologies to enable science operations in the high temperature and pressure near-surface/surfaceenvironment of Venus.

Probabilistic structural analysis methods of hot engine structures

NASA Technical Reports Server (NTRS)

Chamis, C. C.; Hopkins, D. A.

1989-01-01

Development of probabilistic structural analysis methods for hot engine structures at Lewis Research Center is presented. Three elements of the research program are: (1) composite load spectra methodology; (2) probabilistic structural analysis methodology; and (3) probabilistic structural analysis application. Recent progress includes: (1) quantification of the effects of uncertainties for several variables on high pressure fuel turbopump (HPFT) turbine blade temperature, pressure, and torque of the space shuttle main engine (SSME); (2) the evaluation of the cumulative distribution function for various structural response variables based on assumed uncertainties in primitive structural variables; and (3) evaluation of the failure probability. Collectively, the results demonstrate that the structural durability of hot engine structural components can be effectively evaluated in a formal probabilistic/reliability framework.

Hemodynamic changes during weaning: can we assess and predict cardiac-related weaning failure by transthoracic echocardiography?

PubMed Central

2010-01-01

Cardiac-related failure of weaning from mechanical ventilation is an important reason for prolonged mechanical ventilation, intensive care unit treatment, and increased morbidity and mortality. When transthoracic echocardiography (TTE) is routinely performed before a weaning trial, patients at high risk of cardiac-related failure can be detected by low left ventricular (LV) ejection fraction, diastolic dysfunction, and elevated LV filling pressure. During the weaning trial, a further increase of LV filling pressure and progression of diastolic failure can be observed by repeated TTE. Owing to certain limitations concerning patients and methodology, TTE cannot be employed in every patient and invasive hemodynamic monitoring is still mandatory in selected patients with repetitive weaning failure. PMID:20619005

Hemodynamic changes during weaning: can we assess and predict cardiac-related weaning failure by transthoracic echocardiography?

PubMed

Voga, Gorazd

2010-01-01

Cardiac-related failure of weaning from mechanical ventilation is an important reason for prolonged mechanical ventilation, intensive care unit treatment, and increased morbidity and mortality. When transthoracic echocardiography (TTE) is routinely performed before a weaning trial, patients at high risk of cardiac-related failure can be detected by low left ventricular (LV) ejection fraction, diastolic dysfunction, and elevated LV filling pressure. During the weaning trial, a further increase of LV filling pressure and progression of diastolic failure can be observed by repeated TTE. Owing to certain limitations concerning patients and methodology, TTE cannot be employed in every patient and invasive hemodynamic monitoring is still mandatory in selected patients with repetitive weaning failure.

High-NaCl diet impairs dynamic renal blood flow autoregulation in rats with adenine-induced chronic renal failure.

PubMed

Saeed, Aso; DiBona, Gerald F; Grimberg, Elisabeth; Nguy, Lisa; Mikkelsen, Minne Line Nedergaard; Marcussen, Niels; Guron, Gregor

2014-03-15

This study examined the effects of 2 wk of high-NaCl diet on kidney function and dynamic renal blood flow autoregulation (RBFA) in rats with adenine-induced chronic renal failure (ACRF). Male Sprague-Dawley rats received either chow containing adenine or were pair-fed an identical diet without adenine (controls). After 10 wk, rats were randomized to either remain on the same diet (0.6% NaCl) or to be switched to high 4% NaCl chow. Two weeks after randomization, renal clearance experiments were performed under isoflurane anesthesia and dynamic RBFA, baroreflex sensitivity (BRS), systolic arterial pressure variability (SAPV), and heart rate variability were assessed by spectral analytical techniques. Rats with ACRF showed marked reductions in glomerular filtration rate and renal blood flow (RBF), whereas mean arterial pressure and SAPV were significantly elevated. In addition, spontaneous BRS was reduced by ∼50% in ACRF animals. High-NaCl diet significantly increased transfer function fractional gain values between arterial pressure and RBF in the frequency range of the myogenic response (0.06-0.09 Hz) only in ACRF animals (0.3 ± 4.0 vs. -4.4 ± 3.8 dB; P < 0.05). Similarly, a high-NaCl diet significantly increased SAPV in the low-frequency range only in ACRF animals. To conclude, a 2-wk period of a high-NaCl diet in ACRF rats significantly impaired dynamic RBFA in the frequency range of the myogenic response and increased SAPV in the low-frequency range. These abnormalities may increase the susceptibility to hypertensive end-organ injury and progressive renal failure by facilitating pressure transmission to the microvasculature.

Interplay between structural and magnetic-electronic responses of FeA l2O4 to a megabar: Site inversion and spin crossover

NASA Astrophysics Data System (ADS)

Xu, W. M.; Hearne, G. R.; Layek, S.; Levy, D.; Pasternak, M. P.; Rozenberg, G. Kh.; Greenberg, E.

2018-02-01

X-ray diffraction pressure studies at room temperature demonstrate that the spinel FeA l2O4 transforms to a tetragonal phase at ˜18 GPa. This tetragonal phase has a highly irregular unit-cell volume versus pressure dependence up to ˜45 GPa, after which a transformation to a Cmcm postspinel phase is onset. This is attributable to pressure driven Fe↔Al site inversion at room temperature, corroborated by signatures in the 57Fe Mössbauer spectroscopy pressure data. At the tetragonal→postspinel transition, onset in the range 45-50 GPa, there is a concurrent emergence of a nonmagnetic spectral component in the Mössbauer data at variable cryogenic temperatures. This is interpreted as spin crossover at sixfold coordinated Fe locations emanated from site inversion. Spin crossover commences at the end of the pressure range of the tetragonal phase and progresses in the postspinel structure. There is also a much steeper volume change ΔV /V ˜ 10% in the range 45-50 GPa compared to the preceding pressure regime, from the combined effects of the structural transition and spin crossover electronic change. At the highest pressure attained, ˜106 GPa, the Mössbauer data evidence a diamagnetic Fe low-spin abundance of ˜50%. The rest of the high-spin Fe in eightfold coordinated sites continue to experience a relatively small internal magnetic field of ˜33 T. This is indicative of a magnetic ground state associated with strong covalency, as well as substantive disorder from site inversion and the mixed spin-state configuration. Intriguingly, magnetism survives in such a spin-diluted postspinel lattice at high densities. The R (300 K) data decrease by only two orders of magnitude from ambient pressure to the vicinity of ˜100 GPa. Despite a ˜26% unit-cell volume densification from the lattice compressibility, structural transitions, and spin crossover, FeA l2O4 is definitively nonmetallic with an estimated gap of ˜400 meV at ˜100 GPa. At such high densification appreciable bandwidth broadening and gap closure would be anticipated. Reasons for the resilient nonmetallic behavior are briefly discussed.

Aerodynamic instability: A case history

NASA Technical Reports Server (NTRS)

Eisenmann, R. C.

1985-01-01

The identification, diagnosis, and final correction of complex machinery malfunctions typically require the correlation of many parameters such as mechanical construction, process influence, maintenance history, and vibration response characteristics. The progression is reviewed of field testing, diagnosis, and final correction of a specific machinery instability problem. The case history presented addresses a unique low frequency instability problem on a high pressure barrel compressor. The malfunction was eventually diagnosed as a fluidic mechanism that manifested as an aerodynamic disturbance to the rotor assembly.

Petrology and fluid inclusions of garnet-clinopyroxene rocks from the Gondwana suture zone in southern India: Implications for prograde high-pressure metamorphism

NASA Astrophysics Data System (ADS)

Tsunogae, T.

2012-04-01

The Palghat-Cauvery Suture Zone (PCSZ) in the southern granulite terrane, India, which separates Pan-African granulite blocks (e.g., Madurai and Trivandrum Blocks) to the south and Archean terrane (e.g., Salem Block and Dharwar Craton) to the north is regarded as a major suture zone in the Gondwana collisional orogeny. It probably continues westwards to the Betsimisaraka suture in Madagascar, and eastwards into Sri Lanka and possibly into Antarctica. The available geochronological data including U-Pb zircon and EPMA monazite ages indicate that the rocks along the PCSZ underwent an episode of high-grade metamorphism at ca. 530 Ma that broadly coincides with the time of final assembly of the Gondwana supercontinent. Recent investigations on high-grade metamorphic rocks in this region have identified several new occurrences of garnet-clinopyroxene rocks and associated meta-gabbros from Perundurai, Paramati, Aniyapuram, Vadugappatti, and Mahadevi areas in Namakkal region within the central domain of the PCSZ. They occur as elongated boudins of 1 m to 1 km in length within hornblende-biotite orthogneiss. The garnet-clinopyroxene mafic granulites contain coarse-grained (up to several cm) garnet (Alm30-50 Pyr30-40 Grs10-20) and clinopyroxene (XMg = 0.70-0.85) with minor pargasite, plagioclase (An30-40), orthopyroxene (hypersthene), and rutile. Garnet and clinopyroxene are both subidioblastic and contain few inclusions of clinopyroxene (in garnet) and plagioclase. Orthopyroxene occur only as Opx + Pl symplectite between garnet and clinopyroxene in almost all the localities, suggesting the progress of decompressional reaction: Grt + Cpx + Qtz => Opx + Pl, which is a dominant texture in the PCSZ. The prograde mineral assemblage of the rocks is therefore inferred to be Grt + Cpx + Qtz, although quartz was probably totally consumed by the progress of the reaction. The metamorphic P-T calculations using Grt-Cpx-Pl-Qtz geothermobarometers yield T = 850-900°C and P >13 kbar, which is consistent with the occurrence of high-pressure Mg-rich staurolite in Mg-Al-rich rocks from this region. Fluid inclusion study of some garnet-clinopyroxene rock samples identified CO2-rich fluid inclusions trapped as primary phases within garnet, suggesting that prograde high-pressure metamorphism was dominated by CO2-rich fluids. The results therefore confirmed that the PCSZ underwent regional dry high-pressure metamorphism followed by the peak ultrahigh-temperature event probably associated with the continent-continent collisional and suturing history along the PCSZ.

Metabolic activity, experiment M171. [space flight effects on human metabolism

NASA Technical Reports Server (NTRS)

Michel, E. L.; Rummel, J. A.

1973-01-01

The Skylab metabolic activity experiment determines if man's metabolic effectiveness in doing mechanical work is progressively altered by a simulated Skylab environment, including environmental factors such as slightly increased pCO2. This test identified several hardware/procedural anomalies. The most important of these were: (1) the metabolic analyzer measured carbon dioxide production and expired water too high; (2) the ergometer load module failed under continuous high workload conditions; (3) a higher than desirable number of erroneous blood pressure measurements were recorded; (4) vital capacity measurements were unreliable; and (5) anticipated crew personal exercise needs to be more structured.

Porosity and environment

NASA Technical Reports Server (NTRS)

Piwonka, T. S.

1984-01-01

Significant progress was achieved when it was realized that porosity could be analyzed successfully by considering not only heat flow, but also fluid flow within the solidifying casting. Sound castings may be produced by lowering pressure during melting (to allow dissolved gas to escape the melt) and increasing pressure during solidification (to force liquid metal into the mushy zone to feed shrinkage). Such techniques are especially effective if they are combined with chilling of parts of the casting to produce progressive solidification, which shortens the mushy zone and, hence, the distance that metal must travel to feed porosity.

Comparison of MELCOR and SCDAP/RELAP5 results for a low-pressure, short-term station blackout at Browns Ferry

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

Carbajo, J.J.

1995-12-31

This study compares results obtained with two U.S. Nuclear Regulatory Commission (NRC)-sponsored codes, MELCOR version 1.8.3 (1.8PQ) and SCDAP/RELAP5 Mod3.1 release C, for the same transient - a low-pressure, short-term station blackout accident at the Browns Ferry nuclear plant. This work is part of MELCOR assessment activities to compare core damage progression calculations of MELCOR against SCDAP/RELAP5 since the two codes model core damage progression very differently.

Pulse Wave Velocity Predicts the Progression of Blood Pressure and Development of Hypertension in Young Adults.

PubMed

Koivistoinen, Teemu; Lyytikäinen, Leo-Pekka; Aatola, Heikki; Luukkaala, Tiina; Juonala, Markus; Viikari, Jorma; Lehtimäki, Terho; Raitakari, Olli T; Kähönen, Mika; Hutri-Kähönen, Nina

2018-03-01

The aim of the present study was to examine whether pulse wave velocity (PWV) predicts the progression of blood pressure and the development of hypertension in young adults. In addition, we studied whether PWV improves the risk prediction of incident hypertension beyond traditional cardiovascular risk factors. Systolic and diastolic blood pressures were measured in 2007 and 2011 for 1449 Finnish adults (aged 30-45 years). In addition, PWV and other cardiovascular risk factors were measured in 2007. The association between PWV (in 2007) and blood pressure (in 2011) was studied in the whole population (n=1449) and in a normotensive subpopulation (n=1183). The ability of PWV measured in 2007 to predict incident hypertension in 2011 was investigated in the subpopulation (n=1183). PWV measured in 2007 was directly and independently associated with systolic and diastolic blood pressures measured in 2011 ( P <0.001 for both). PWV measured in 2007 was also an independent predictor of incident hypertension in 2011 (odds ratio, 1.96 per 1-SDincrease; 95% confidence interval, 1.51-2.57; P <0.001). The extended prediction model (including PWV) improved the incident hypertension risk prediction beyond traditional cardiovascular risk factors, the area under receiver operating characteristics curve being 0.833 versus 0.809 ( P =0.040), and the continuous net reclassification improvement 59.4% ( P <0.001). These findings suggest that PWV predicts the progression of blood pressure and could provide a valuable tool in hypertension risk prediction in young adults. © 2018 American Heart Association, Inc.

Evolution of ferromagnetism in charge ordered manganite: An effect of external pressure

NASA Astrophysics Data System (ADS)

Dash, S.; Pradhan, M. K.; Rao, T. Lakshmana

2018-05-01

Detailed magnetic measurements of the Pr0.75Na0.25MnO3 polycrystalline sample have been carried out under external hydrostatic pressure upto 10kbar. Pressure strongly suppresses the first order magnetic transition, while thermal hysteresis narrows down progressively and then disappears with increase in pressure. The significant enhancement of the field cooled magnetization value at different pressures is due to the antiferromagnetic to ferromagnetic transformation, while ruling out any contribution from the domain alignment within the ferromagnetic phase.

Structural relaxation of vitreous albite near Tg and implications for transport properties of the supercooled liquid at high pressure

NASA Astrophysics Data System (ADS)

Gaudio, S. J.; Lesher, C. E.

2012-12-01

We estimate the glass transition temperature, Tg, for vitreous/amorphous albite between 0 and 7.7 GPa by tracking the progress of densification following high-temperature annealing experiments with run durations equal to 5τ (when τ=100 s). Tg decreases by 54 K/GPa up to 2.6 GPa, and thereafter shows a weak negative pressure dependence. This behavior mimics the negative pressure dependence of viscosity of albite liquid shown by [1]; however, we do not find a change in the sign of ∂Tg/∂P at least up to 7.7 GPa as reported in some isothermal ∂η/∂P, and ∂DO/∂P data sets. Our high field (21.8 T) 27Al MAS NMR measurements of recovered glasses rapidly quenched from super-Tg conditions possess trace amounts of high coordinated Al at 2.6 GPa and only ˜17% by 5.5 GPa. This suggests that the decrease in Tg (and viscosity at low temperature) results dominantly from topological rearrangement of the supercooled melt structure and not changes to Al or Si coordination number and connectivity of the network. In fact, at Tg from 0 to 8 GPa, the XNBO, or network connectivity, is unchanged [2] and at 7.7 GPa, we find the proportion of high coordinated Al is still ˜35%. Convergence in the timescales of relaxation at Tg(P) and the onset of Na mobility to 6 GPa documented by high-pressure electrical conductivity measurements [3] implies that the fragility of albite melt increases with pressure up to ˜4-5 GPa, without changing the effective polymerization of the melt. In contrast, fragility appears to decrease with pressure in partially depolymerized silicate melts. Such differences in fragility can be used for extrapolation of activation energy based models for viscous flow to high pressure. [1] Kushiro, 1978, EPSL, 41; Brearley et al., 1986, GCA, 50; Brearley and Montana, 1989, GCA, 53; Poe et al., 1997, Science, 276; Suzuki et al., 2002, Phys. Chem. Miner., 29; Funakoshi et al., 2002, J. Phys.: Condens. Matter., 14; Behrens and Schulze, 2003, Am. Min., 88. [2] Lee et al. 2004, GCA, 68; [3] Bagdassarov et al., 2004, Phys. Chem. Glasses, 45.

The prognostic reliability of intracranial pressure monitoring and MRI data in severe traumatic brain injury.

PubMed

Woischneck, Dieter; Kapapa, Thomas

2017-02-01

The predictive quality of intracranial pressure (ICP) monitoring has for many years been a matter of debate. We correlate ICP data comparing MRI data with the outcome after severe traumatic brain injury to evaluate their prognostic potency. This study compares the results of ICP monitoring, MRI, coma duration and outcome according to Glasgow Outcome Scale obtained in 32 patients having suffered severe TBI. Level of significance was set to p≤0.05 in statistical tests. The MRI results were closely correlated with coma duration and Glasgow Outcome Scale, but the ICP measurements were not. With the exception of severe, bipontine lesions, there is no other region of the brain in which increased evidence of traumatogenic lesions emerges as the intracranial pressure rises. Just bipontine lesions that proof to be infaust correlate with elevated ICP values. ICP monitoring does not allow individual prognostic conclusions to be made. Implantation of an intracranial pressure sensor alone for making a prognostic estimate is not advisable. The use of intracranial pressure measurements in the retrospective appraisal of disease progress is highly problematic. However, MRI diagnostic in patients with severe TBI improves prognostic potency of clinical parameters. Copyright © 2016 Elsevier Inc. All rights reserved.

Comparison of Plasma Polymerization under Collisional and Collision-Less Pressure Regimes.

PubMed

Saboohi, Solmaz; Jasieniak, Marek; Coad, Bryan R; Griesser, Hans J; Short, Robert D; Michelmore, Andrew

2015-12-10

While plasma polymerization is used extensively to fabricate functionalized surfaces, the processes leading to plasma polymer growth are not yet completely understood. Thus, reproducing processes in different reactors has remained problematic, which hinders industrial uptake and research progress. Here we examine the crucial role pressure plays in the physical and chemical processes in the plasma phase, in interactions at surfaces in contact with the plasma phase, and how this affects the chemistry of the resulting plasma polymer films using ethanol as the gas precursor. Visual inspection of the plasma reveals a change from intense homogeneous plasma at low pressure to lower intensity bulk plasma at high pressure, but with increased intensity near the walls of the chamber. It is demonstrated that this occurs at the transition from a collision-less to a collisional plasma sheath, which in turn increases ion and energy flux to surfaces at constant RF power. Surface analysis of the resulting plasma polymer films show that increasing the pressure results in increased incorporation of oxygen and lower cross-linking, parameters which are critical to film performance. These results and insights help to explain the considerable differences in plasma polymer properties observed by different research groups using nominally similar processes.

Transparent, Superflexible Doubly Cross-Linked Polyvinylpolymethylsiloxane Aerogel Superinsulators via Ambient Pressure Drying.

PubMed

Zu, Guoqing; Shimizu, Taiyo; Kanamori, Kazuyoshi; Zhu, Yang; Maeno, Ayaka; Kaji, Hironori; Shen, Jun; Nakanishi, Kazuki

2018-01-23

Aerogels have many attractive properties but are usually costly and mechanically brittle, which always limit their practical applications. While many efforts have been made to reinforce the aerogels, most of the reinforcement efforts sacrifice the transparency or superinsulating properties. Here we report superflexible polyvinylpolymethylsiloxane, (CH 2 CH(Si(CH 3 )O 2/2 )) n , aerogels that are facilely prepared from a single precursor vinylmethyldimethoxysilane or vinylmethyldiethoxysilane without organic cross-linkers. The method is based on consecutive processes involving radical polymerization and hydrolytic polycondensation, followed by ultralow-cost, highly scalable, ambient-pressure drying directly from alcohol as a drying medium without any modification or additional solvent exchange. The resulting aerogels and xerogels show a homogeneous, tunable, highly porous, doubly cross-linked nanostructure with the elastic polymethylsiloxane network cross-linked with flexible hydrocarbon chains. An outstanding combination of ultralow cost, high scalability, uniform pore size, high surface area, high transparency, high hydrophobicity, excellent machinability, superflexibility in compression, superflexibility in bending, and superinsulating properties has been achieved in a single aerogel or xerogel. This study represents a significant progress of porous materials and makes the practical applications of transparent flexible aerogel-based superinsulators realistic.

A human model of restricted upper esophageal sphincter opening and its pharyngeal and UES deglutitive pressure phenomena

PubMed Central

Jiao, Hongmei; Mei, Ling; Sharma, Tarun; Kern, Mark; Sanvanson, Patrick

2016-01-01

Oropharyngeal dysphagia due to upper esophageal sphincter (UES) dysfunction is commonly encountered in the clinical setting. Selective experimental perturbation of various components of the deglutitive apparatus can provide an opportunity to improve our understanding of the swallowing physiology and pathophysiology. The aim is to characterize the pharyngeal and UES deglutitive pressure phenomena in an experimentally induced restriction of UES opening in humans. We studied 14 volunteers without any dysphagic symptoms (7 men, 66 ± 11 yr) but with various supraesophageal reflux symptoms. To induce UES restriction, we used a handmade device that with adjustment could selectively apply 0, 20, 30, or 40 mmHg pressure perpendicularly to the cricoid cartilage. Deglutitive pharyngeal and UES pressure phenomena were determined during dry and 5- and 10-ml water swallows × 3 for each of the UES perturbations. External cricoid pressure against the UES resulted in a significant increase in hypopharyngeal intrabolus pressure and UES nadir deglutitive relaxation pressure for all tested swallowed volumes (P < 0.05). Application of external cricoid pressure increased the length of the UES high pressure zone from 2.5 ± 0.2 to 3.1 ± 0.2, 3.5 ± 0.1, and 3.7 ± 0.1 cm for 20, 30, and 40 mmHg cricoid pressure, respectively (P < 0.05). External cricoid pressure had no significant effect on pharyngeal peristalsis. On the other hand, irrespective of external cricoid pressure deglutitive velopharyngeal contractile integral progressively increased with increased swallowed volumes (P < 0.05). In conclusion, acute experimental restriction of UES opening by external cricoid pressure manifests the pressure characteristics of increased resistance to UES transsphincteric flow observed clinically without affecting the pharyngeal peristaltic contractile function. PMID:27198193

Cardiovascular Response to Recreational Hockey in Middle-Aged Men.

PubMed

Goodman, Zack A; Thomas, Scott G; Wald, Robert C; Goodman, Jack M

2017-06-15

The present study examined the hemodynamic response to recreational pick-up hockey relative to maximal exercise testing in middle-aged men. A total of 23 men with a mean age of 53 ± 7 years were studied. Graded exercise testing on a cycle ergometer determined maximal oxygen consumption, blood pressure (BP), and heart rate (HR). Ambulatory BP and Holter electrocardiographic monitoring was performed during one of their weekly hockey games (mean duration = 45 ± 7.2 minutes): for "On-Ice" responses (PLAY; data recorded while standing immediately after a shift; 8.0 ± 1.4 shifts per game) and during seated recovery (BENCH), 15 minutes after the game. On-Ice HRs and BPs were significantly higher than values obtained during maximal cycle exercise, respectively (HR 174 ± 8.9 vs 163 ± 11.0 beats/min) (systolic blood pressure 202 ± 20 vs 173 ± 31 mm Hg; p <0.05). Both systolic and diastolic blood pressures decreased significantly throughout the duration of the game, whereas HR increased from 139 ± 20 to 155 ± 16 beats/min during the game. The myocardial oxygen demand (myocardial time tension index) increased significantly during PLAY concurrent with a decrease in estimated myocardial oxygen supply (diastolic pressure time index), with the endocardial viability ratio during PLAY demonstrating a significant decrease during the third quarter of the game (1.25 ± 0.24) versus the first quarter (1.56 ± 0.30), which remained depressed 15 minutes post-game (p <0.05). In conclusion, recreational pick-up hockey in middle-aged men is an extremely vigorous interval exercise with increasing relative intensity as the game progresses. Hockey elicits peak BPs and HRs that can exceed values observed during maximal exercise testing and is characterized by progressive increases in myocardial oxygen demand and lowered supply during PLAY and BENCH time. Given the progressive and high cardiovascular demands, caution is warranted when estimating the cardiovascular demands of hockey from clinical stress testing, particularly in those whom coronary reserve may be compromised. Copyright © 2017 Elsevier Inc. All rights reserved.

Greater nighttime blood pressure variability is associated with left atrial enlargement in atrial fibrillation patients with preserved ejection fraction.

PubMed

Norioka, Naoki; Iwata, Shinichi; Ito, Asahiro; Tamura, Soichiro; Kawai, Yu; Nonin, Shinichi; Ishikawa, Sera; Doi, Atsushi; Hanatani, Akihisa; Yoshiyama, Minoru

2018-06-13

Left atrial enlargement is an independent risk factor for ischemic stroke in patients with atrial fibrillation. Little is known regarding the association between nighttime blood pressure variability and left atrial enlargement in patients with atrial fibrillation and preserved ejection fraction. The study population consisted of 140 consecutive patients with atrial fibrillation (mean age 64 ± 10 years) with preserved ejection fraction (≥50%). Nighttime blood pressure was measured at hourly intervals, using a home blood pressure monitoring device. Nighttime blood pressure variability was expressed as the standard deviation of all readings. Left atrial volume index was measured using the modified Simpson's biplane method with transthoracic echocardiography. Multiple regression analysis indicated that nighttime mean systolic/diastolic blood pressure and its variability remained independently associated with left atrial enlargement after adjustment for age, sex, anti-hypertensive medication class, and left ventricular mass index (P < 0.01). When patients were divided into four groups according to nighttime blood pressure and its variability, the group with higher nighttime blood pressure and its variability had significantly larger left atrial volume than the group with lower nighttime blood pressure and its variability (46.6 ml/m 2 vs. 35.0 ml/m 2 , P < 0.0001). Higher nighttime blood pressure and its variability are associated with left atrial enlargement. The combination of nighttime blood pressure and its variability has additional predictive value for left atrial enlargement. Intensive intervention for these high-risk patients may avoid or delay progression of left atrial enlargement and reduce the risk of stroke.

Responses to negative pressure surrounding the neck in anesthetized animals.

PubMed

Wolin, A D; Strohl, K P; Acree, B N; Fouke, J M

1990-01-01

Continuous positive pressure applied at the nose has been shown to cause a decrease in upper airway resistance. The present study was designed to determine whether a similar positive transmural pressure gradient, generated by applying a negative pressure at the body surface around the neck, altered upper airway patency. Studies were performed in nine spontaneously breathing anesthetized supine dogs. Airflow was measured with a pneumotachograph mounted on an airtight muzzle placed over the nose and mouth of each animal. Upper airway pressure was measured as the differential pressure between the extrathoracic trachea and the inside of the muzzle. Upper airway resistance was monitored as an index of airway patency. Negative pressure (-2 to -20 cmH2O) was applied around the neck by using a cuirass extending from the jaw to the thorax. In each animal, increasingly negative pressures were transmitted to the airway wall in a progressive, although not linear, fashion. Decreasing the pressure produced a progressive fall in upper airway resistance, without causing a significant change in respiratory drive or respiratory timing. At -5 cmH2O pressure, there occurred a significant fall in upper airway resistance, comparable with the response of a single, intravenous injection of sodium cyanide (0.5-3.0 mg), a respiratory stimulant that produces substantial increases in respiratory drive. We conclude that upper airway resistance is influenced by the transmural pressure across the airway wall and that such a gradient can be accomplished by making the extraluminal pressure more negative.(ABSTRACT TRUNCATED AT 250 WORDS)

Moderately high frequency ventilation with a conventional ventilator allows reduction of tidal volume without increasing mean airway pressure.

PubMed

Cordioli, Ricardo Luiz; Park, Marcelo; Costa, Eduardo Leite Vieira; Gomes, Susimeire; Brochard, Laurent; Amato, Marcelo Britto Passos; Azevedo, Luciano Cesar Pontes

2014-12-01

The aim of this study was to explore if positive-pressure ventilation delivered by a conventional ICU ventilator at a moderately high frequency (HFPPV) allows a safe reduction of tidal volume (V T) below 6 mL/kg in a porcine model of severe acute respiratory distress syndrome (ARDS) and at a lower mean airway pressure than high-frequency oscillatory ventilation (HFOV). This is a prospective study. In eight pigs (median weight 34 [29,36] kg), ARDS was induced by pulmonary lavage and injurious ventilation. The animals were ventilated with a randomized sequence of respiratory rates: 30, 60, 90, 120, 150, followed by HFOV at 5 Hz. At each step, V T was adjusted to allow partial pressure of arterial carbon dioxide (PaCO2) to stabilize between 57 and 63 mmHg. Data are shown as median [P25th,P75th]. After lung injury, the PaO2/FiO2 (P/F) ratio was 92 [63,118] mmHg, pulmonary shunt 26 [17,31]%, and static compliance 11 [8,14] mL/cmH2O. Positive end-expiratory pressure (PEEP) was 14 [10,17] cmH2O. At 30 breaths/min, V T was higher than 6 (7.5 [6.8,10.2]) mL/kg, but at all higher frequencies, V T could be reduced and PaCO2 maintained, leading to reductions in plateau pressures and driving pressures. For frequencies of 60 to 150/min, V T progressively fell from 5.2 [5.1,5.9] to 3.8 [3.7,4.2] mL/kg (p < 0.001). There were no detrimental effects in terms of lung mechanics, auto-PEEP generation, hemodynamics, or gas exchange. Mean airway pressure was maintained constant and was increased only during HFOV. During protective mechanical ventilation, HFPPV delivered by a conventional ventilator in a severe ARDS swine model safely allows further tidal volume reductions. This strategy also allowed decreasing airway pressures while maintaining stable PaCO2 levels.

Progressive Fracture of Laminated Fiber-Reinforced Composite Stiffened Plate Under Pressure

NASA Technical Reports Server (NTRS)

Gotsis, Pascalis K.; Abdi, Frank; Chamis, Christos C.; Tsouros, Konstantinos

2007-01-01

S-Glass/epoxy laminated fiber-reinforced composite stiffened plate structure with laminate configuration (0/90)5 was simulated to investigate damage and fracture progression, under uniform pressure. For comparison reasons a simple plate was examined, in addition with the stiffened plate. An integrated computer code was used for the simulation. The damage initiation began with matrix failure in tension, continuous with damage and/or fracture progression as a result of additional matrix failure and fiber fracture and followed by additional interply delamination. Fracture through the thickness began when the damage accumulation was 90%. After that stage, the cracks propagate rapidly and the structures collapse. The collapse load for the simple plate is 21.57 MPa (3120 psi) and for the stiffened plate 25.24 MPa (3660 psi).

Quantitative Measurements of Nitric Oxide Concentration in High-Pressure, Swirl-Stabilized Spray Flames

NASA Technical Reports Server (NTRS)

Cooper, Clayton S.; Laurendeau, Normand M.; Hicks, Yolanda R. (Technical Monitor)

2000-01-01

Lean direct-injection (LDI) spray flames offer the possibility of reducing NO(sub x) emissions from gas turbines by rapid mixing of the liquid fuel and air so as to drive the flame structure toward partially-premixed conditions. We consider the technical approaches required to utilize laser-induced fluorescence methods for quantitatively measuring NO concentrations in high-pressure LDI spray flames. In the progression from atmospheric to high-pressure measurements, the LIF method requires a shift from the saturated to the linear regime of fluorescence measurements. As such, we discuss quantitative, spatially resolved laser-saturated fluorescence (LSF), linear laser-induced fluorescence (LIF), and planar laser-induced fluorescence (PLIF) measurements of NO concentration in LDI spray flames. Spatially-resolved LIF measurements of NO concentration (ppm) are reported for preheated, LDI spray flames at pressures of two to five atmospheres. The spray is produced by a hollow-cone, pressure-atomized nozzle supplied with liquid heptane. NO is excited via the Q(sub 2)(26.5) transition of the gamma(0,0) band. Detection is performed in a two nanometer region centered on the gamma(0,1) band. A complete scheme is developed by which quantitative NO concentrations in high-pressure LDI spray flames can be measured by applying linear LIF. NO is doped into the reactants and convected through the flame with no apparent destruction, thus allowing a NO fluorescence calibration to be taken inside the flame environment. The in-situ calibration scheme is validated by comparisons to a reference flame. Quantitative NO profiles are presented and analyzed so as to better understand the operation of lean-direct injectors for gas turbine combustors. Moreover, parametric studies are provided for variations in pressure, air-preheat temperature, and equivalence ratio. Similar parametric studies are performed for lean, premixed-prevaporized flames to permit comparisons to those for LDI flames. Finally, PLIF is expanded to high pressure in an effort to quantify the detected fluorescence image for LDI flames. Success is achieved by correcting the PLIF calibration via a single-point LIF measurement. This procedure removes the influence of any preferential background that occurs in the PLIF detection window. In general, both the LIF and PLIF measurements verify that the LDI strategy could be used to reduce NO(sub x) emissions in future gas turbine combustors.

Deformation of olivine under mantle conditions: An in situ high-pressure, high-temperature study using monochromatic synchrotron radiation

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

Hilairet, Nadège; Wang, Yanbin; Sanehira, Takeshi

2012-03-15

Polycrystalline samples of San Carlos olivine were deformed at high-pressure (2.8-7.8 GPa), high-temperature (1153 to 1670 K), and strain rates between 7.10{sup -6} and 3.10{sup -5} s{sup -1}, using the D-DIA apparatus. Stress and strain were measured in situ using monochromatic X-rays diffraction and imaging, respectively. Based on the evolution of lattice strains with total bulk strain and texture development, we identified three deformation regimes, one at confining pressures below 3-4 GPa, one above 4 GPa, both below 1600 K, and one involving growth of diffracting domains associated with mechanical softening above {approx}1600 K. The softening is interpreted as enhancedmore » grain boundary migration and recovery. Below 1600 K, elasto-plastic self-consistent analysis suggests that below 3-4 GPa, deformation in olivine occurs with large contribution from the so-called 'a-slip' system [100](010). Above {approx}4 GPa, the contribution of the a-slip decreases relative to that of the 'c-slip' [001](010). This conclusion is further supported by texture refinements. Thus for polycrystalline olivine, the evolution in slip systems found by previous studies may be progressive, starting from as low as 3-4 GPa and up to 8 GPa. During such a gradual change, activation volumes measured on polycrystalline olivine cannot be linked to a particular slip system straightforwardly. The quest for 'the' activation volume of olivine at high pressure should cease at the expense of detailed work on the flow mechanisms implied. Such evolution in slip systems should also affect the interpretation of seismic anisotropy data in terms of upper mantle flow between 120 and 300 km depth.« less

Through-thickness recrystallization characteristics of a laminated AA3xxx–AA6xxx aluminum alloy system

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

Liao, L.H., E-mail: l2liao@uwaterloo.ca; Jin, H.; Gallerneault, M.

2015-03-15

The through-thickness annealing behavior of a laminated AA3xxx–AA6xxx alloy system at 300 °C has been studied by scanning electron microscopy, electron backscatter diffraction analysis, electron probe micro-analysis, differential scanning calorimetry, and hardness measurement. Results show that the recrystallization process starts at the interface region between the AA3xxx (clad) and AA6xxx (core) layers. Subsequently, the recrystallization process front progresses into the core layer, while the clad layer is the last region to recrystallize. It is also found that precipitation precedes recrystallization in the entire laminate at the investigated temperature. The preferential onset of recrystallization at the interface region is attributed tomore » the net driving pressure being the highest in this region. The factors that lead to such enhanced net driving pressure are (a) deformation incompatibility between the two alloy layers, (b) lower solute content of the interface, which also leads to lower volume fraction of precipitates, and (c) an accelerated rate of precipitate coarsening due to the presence of a higher density of dislocations. The gradual progress of recrystallization from the interface towards the core layer is dictated by precipitate coarsening and the dependence of its rate on the density of deformation-induced dislocations. The lower driving pressure due to lower work hardening capacity, high solute drag pressure due to Mn, and additional Zener drag from precipitates that form due to solute redistribution during annealing explain the late initiation of recrystallization in the clad layer. - Highlights: • The through-thickness recrystallization of a laminated system is investigated. • The early onset of recrystallization at the interface is discussed. • The effects of precipitation and coarsening on recrystallization are analyzed.« less

Damage Recovery in Carrara Marble

NASA Astrophysics Data System (ADS)

Meyer, G.; Brantut, N.; Mitchell, T. M.; Meredith, P. G.

2017-12-01

We investigate the effect of confining pressure on the recovery of elastic wave velocities following deformation episodes in Carrara Marble. Dry Carrara Marble cores were deformed in the ductile regime (Pc = 40 MPa) up to 3% axial strain. After deformation, samples were held at constant stress conditions for extended periods of time (5-8 days) whilst continuously recording volumetric strain and seismic wave velocities. The velocity data were used to invert for microcrack densities using an effective medium approach. Finally, thin sections were produced to characterise the microstructures after recovery. During deformation, elastic wave speeds decreased with increasing strain by more than 30% of the value for the intact rock due to the formation of distributed microcracks. Under constant hydrostatic pressure, wave speeds progressively recovered 12-90% of the initial drop, depending on the applied confining pressure. In contrast, the strain recovery (deformation towards the initial shape of the sample) during holding time is negligible (of the order of 10-4). Tests performed under nonhydrostatic (triaxial) stress conditions during recovery showed some time-dependent creep deformation together with very significant recovery of wave velocities. The recovery is interpreted as a progressive reduction in crack density within the sample. The process is highly dependent on confining pressure, which favours it. We propose that the driving process for wave speed recovery is the time-dependent increase of contact area between crack surfaces due to the formation and growth of asperity contacts. We develop a micromechanical model for crack closure driven by asperity creep, which shows a good fit to the experimental data. Most of the recovery is achieved in the initial few hours, implying it is the fastest recovery or healing process, and thus occurs prior to any chemical healing or mineral precipitation. Our data corroborate field observations of post-seismic fault behavior.

Annual Research Progress Report, Fiscal Year 1988. Volume 1. (Brooke Army Medical Center)

DTIC Science & Technology

1988-10-01

Fresh Water Contaminated Wounds and 56 the Incidence of Wound Infections Associated with These Injuries . (0) C-67-86 The Choice of Antibiotics for Marine...Catheterization. (0) C-35-88 Evaluation of Luque Interpeduncular Segmental Excision in Spinal 267 Injury . (0) C-38-88 Bone Density Changes with...delivery. Am. J. Emerg. Med., 6(6):206, May 88. Chisholm, C., Curka. High pressure water injection injury of the hand. Am. J. Emerg. Med., (in press

Server-based enterprise collaboration software improves safety and quality in high-volume PET/CT practice.

PubMed

McDonald, James E; Kessler, Marcus M; Hightower, Jeremy L; Henry, Susan D; Deloney, Linda A

2013-12-01

With increasing volumes of complex imaging cases and rising economic pressure on physician staffing, timely reporting will become progressively challenging. Current and planned iterations of PACS and electronic medical record systems do not offer workflow management tools to coordinate delivery of imaging interpretations with the needs of the patient and ordering physician. The adoption of a server-based enterprise collaboration software system by our Division of Nuclear Medicine has significantly improved our efficiency and quality of service.

Positive expiratory pressure device acceptance by hospitalized children with sickle cell disease is comparable to incentive spirometry.

PubMed

Hsu, Lewis L; Batts, Brenda K; Rau, Joseph L

2005-05-01

The pulmonary complication in sickle cell disease known as acute chest syndrome (ACS) has potential for high morbidity and mortality. A randomized trial demonstrated that incentive spirometry (IS) reduces the rate of ACS, leading to a role for respiratory therapy in hospital management of sickle cell pain. However, use of IS can be limited by chest wall pain, or by difficulty with the coordinated inspiration in a young child. Intermittent positive expiratory pressure (PEP) therapy may be easier for a child's coordination and more comfortable than IS for a child with chest wall pain. To compare PEP therapy with conventional IS for children hospitalized for sickle cell pain with respect to patient satisfaction, length of hospital stay, and progression to ACS. This pilot study enrolled 20 children upon hospitalization for sickle cell pain in the thorax, randomly assigning them to either PEP (n = 11) or IS (n = 9) therapy, administered by a therapist hourly while awake. The randomization assigned an older distribution to PEP than IS (12.3 vs 8.8 y). Patient satisfaction was high for both respiratory care devices, and there was no difference between the PEP and IS groups (4.5 vs 4.4, p = 0.81). Length of hospital stay was similar (5 vs 4.3 d, p = 0.56). No children in either group progressed to ACS. These preliminary results show no difference in the primary outcomes in the 2 groups. Intermittent PEP therapy warrants further study as an alternative to IS for sickle cell patients at high risk for ACS, as effective preventive respiratory therapy.

Comparative urodynamic studies of continent and stress incontinent women in pregnancy and in the puerperium.

PubMed

Iosif, S; Ulmsten, U

1981-07-15

Twelve pregnant women were examined by urethral pressure profile measurement and simultaneous urethrocystometry early in pregnancy (weeks 12 to 16), in the thirty-eighth week, and 5 to 7 days after delivery. All patients reported symptoms of stress incontinence starting at an early 5 to 7 days after delivery. All patients reported symptoms of stress incontinence starting at an early gestational age, it was found that that the stress incontinent women, compared to 14 continent, healthy women from whom measurements were obtained earlier, had shorter urethral lengths. Furthermore, no increase in urethral length during pregnancy was registered among the stress incontinent women, whereas such an increase did occur in the continent women. In contrast to the continent women, the incontinent patients had a low urethral closure pressure at rest and this pressure did not appear to increase sufficiently to compensate for the progressive increase in bladder pressure during pregnancy. As a result the urethral closure pressure in the stress incontinent women, therefore, decreased more and more during stress situations as pregnancy progressed, resulting in an increased leakage of urine.

Single-Shot Scalar-Triplet Measurements in High-Pressure Swirl-Stabilized Flames for Combustion Code Validation

NASA Technical Reports Server (NTRS)

Kojima, Jun; Nguyen, Quang-Viet

2007-01-01

In support of NASA ARMD's code validation project, we have made significant progress by providing the first quantitative single-shot multi-scalar data from a turbulent elevated-pressure (5 atm), swirl-stabilized, lean direct injection (LDI) type research burner operating on CH4-air using a spatially-resolved pulsed-laser spontaneous Raman diagnostic technique. The Raman diagnostics apparatus and data analysis that we present here were developed over the past 6 years at Glenn Research Center. From the Raman scattering data, we produce spatially-mapped probability density functions (PDFs) of the instantaneous temperature, determined using a newly developed low-resolution effective rotational bandwidth (ERB) technique. The measured 3-scalar (triplet) correlations, between temperature, CH4, and O2 concentrations, as well as their PDF s, also provide a high-level of detail into the nature and extent of the turbulent mixing process and its impact on chemical reactions in a realistic gas turbine injector flame at elevated pressures. The multi-scalar triplet data set presented here provides a good validation case for CFD combustion codes to simulate by providing both average and statistical values for the 3 measured scalars.

Dramatic pressure-sensitive ion conduction in conical nanopores.

PubMed

Jubin, Laetitia; Poggioli, Anthony; Siria, Alessandro; Bocquet, Lydéric

2018-04-17

Ion transporters in Nature exhibit a wealth of complex transport properties such as voltage gating, activation, and mechanosensitive behavior. When combined, such processes result in advanced ionic machines achieving active ion transport, high selectivity, or signal processing. On the artificial side, there has been much recent progress in the design and study of transport in ionic channels, but mimicking the advanced functionalities of ion transporters remains as yet out of reach. A prerequisite is the development of ionic responses sensitive to external stimuli. In the present work, we report a counterintuitive and highly nonlinear coupling between electric and pressure-driven transport in a conical nanopore, manifesting as a strong pressure dependence of the ionic conductance. This result is at odds with standard linear response theory and is akin to a mechanical transistor functionality. We fully rationalize this behavior on the basis of the coupled electrohydrodynamics in the conical pore by extending the Poisson-Nernst-Planck-Stokes framework. The model is shown to capture the subtle mechanical balance occurring within an extended spatially charged zone in the nanopore. The pronounced sensitivity to mechanical forcing offers leads in tuning ion transport by mechanical stimuli. The results presented here provide a promising avenue for the design of tailored membrane functionalities.

Potential implications of dose and diet for the effects of cocoa flavanols on cardiometabolic function.

PubMed

Davison, Kade; Howe, Peter R C

2015-11-18

The metabolic syndrome is a pathological state whereby cardiovascular and metabolic dysfunction coexist and typically progress in a mutual feed-forward manner to further dysfunction and ultimately disease. The health and function of the vascular endothelium is integral in this phenomenon and thus represents a logical target for intervention. Consumption of foods high in cocoa flavanols has demonstrated a capacity to markedly improve endothelial function and key markers of the metabolic syndrome including blood pressure and insulin sensitivity. The typically high energy content of foods containing sufficient doses of cocoa flavanols has caused some reservations around its therapeutic use, but this is dependent upon the particulars of the food matrix used. Further to this, the food matrix appears to influence the dose response curve of cocoa flavanols, particularly on blood pressure, with dark chocolate appearing to be 8 times more effective in systolic blood pressure reduction than a cocoa powder drink for the equivalent dose of flavanol. Cocoa flavanol consumption conclusively demonstrates a positive impact on cardiometabolic function; however, more research is needed to understand how best to consume it to maximize the benefit while avoiding excessive fat and sugar consumption.

Structure and Stability of High-Pressure Dolomite with Implications for the Earth's Deep Carbon Cycle

NASA Astrophysics Data System (ADS)

Solomatova, N. V.; Asimow, P. D.

2014-12-01

Carbon is subducted into the mantle primarily in the form of metasomatically calcium-enriched basaltic rock, calcified serpentinites and carbonaceous ooze. The fate of these carbonates in subduction zones is not well understood. End-member CaMg(CO3)2 dolomite typically breaks down into two carbonates at 2-7 GPa, which may further decompose to oxides and CO2-bearing fluid. However, high-pressure X-ray diffraction experiments have recently shown that the presence of iron may be sufficient to stabilize dolomite I to high pressures, allowing the transformation to dolomite II at 17 GPa and subsequently to dolomite III at 35 GPa [1][2]. Such phases may be a principal host for deeply subducted carbon. The structure and equation of state of these high-pressure phases is debated and the effect of varying concentrations of iron is unknown, creating a need for theoretical calculations. Here we compare calculated dolomite structures to experimentally observed phases. Using the Vienna ab-initio simulation package (VASP) interfaced with a genetic algorithm that predicts crystal structures (USPEX), a monoclinic phase with space group 5 ("dolomite sg5") was found for pure end-member dolomite. Dolomite sg5 has a lower energy than reported dolomite structures and an equation of state that resembles that of dolomite III. It is possible that dolomite sg5 is not achieved experimentally due to a large energy barrier and a correspondingly large required volume drop, resulting in the transformation to metastable dolomite II. Due to the complex energy landscape for candidate high-pressure dolomite structures, it is likely that several competing polymorphs exist. Determining the behavior of high-pressure Ca-Mg-Fe(-Mn) dolomite phases in subduction environments is critical for our understanding of the Earth's deep carbon cycle and supercell calculations with Fe substitution are in progress. [1] Mao, Z., Armentrout, M., Rainey, E., Manning, C. E., Dera, P., Prakapenka, V. B., and Kavner, A. (2011). Dolomite III: A new candidate lower mantle carbonate. Geophy. Res. Lett., 38(22). [2] Merlini, M., Crichton, W. A., Hanfland, M., Gemmi, M., Müller, H., Kupenko, I., and Dubrovinsky, L. (2012). Structures of dolomite at ultrahigh pressure and their influence on the deep carbon cycle. Proc. Nat. Acad. Sci., 109(34), 13509-13514.

Assessment of Pulmonary Artery Stiffness of Repaired Congenital Heart Disease Patients

NASA Astrophysics Data System (ADS)

Lee, Namheon; Banerjee, Rajit; Taylor, Michael; Hor, Kan

2012-10-01

Surgical correction or palliation of congenital heart disease (CHD) often requires augmenting the main pulmonary artery (MPA) with non-native material or placing a cylindrical graft. The degree to which this intervention affects PA compliance is largely unknown. In this study, the MPA stiffness characteristics were assessed by its compliance, distensibility, and pressure-strain modulus. Coregistered velocity encoded phase-contrast MRI and cardiac catheterization data were available for a cohort of repaired CHD patients (n=8) and controls (n=3). All patients were repaired with either an RV-PA conduit or a RV outflow tract patch. We measured the MPA area change by MRI and MPA pressure during the cath. The measurements were taken through or just distal to the conduit. The MPA compliance and distensibility for the patients were significantly lower than the controls: compliance (9.8±10.8 vs 28.3±7.7mm^2/mmHg, p<0.05), distensibility (2.2±1.5 vs 6.6±2.1%Area change/mmHg, p=0.05). The patients had a significantly higher pressure-strain modulus (152.3±116.4mmHg, p<0.05) than the controls (35.8±10.6mmHg). The abnormally elevated PA stiffness due to the rigidity of the conduit or patch material may cause a compliance mismatch resulting in high stress levels contributing to the observed progressive PA dilatation. This may be a factor in the progressive RV dilatation seen in this cohort of repaired CHD patients.

Muscle Performance Investigated With a Novel Smart Compression Garment Based on Pressure Sensor Force Myography and Its Validation Against EMG.

PubMed

Belbasis, Aaron; Fuss, Franz Konstantin

2018-01-01

Muscle activity and fatigue performance parameters were obtained and compared between both a smart compression garment and the gold-standard, a surface electromyography (EMG) system during high-speed cycling in seven participants. The smart compression garment, based on force myography (FMG), comprised of integrated pressure sensors that were sandwiched between skin and garment, located on five thigh muscles. The muscle activity was assessed by means of crank cycle diagrams (polar plots) that displayed the muscle activity relative to the crank cycle. The fatigue was assessed by means of the median frequency of the power spectrum of the EMG signal; the fractal dimension (FD) of the EMG signal; and the FD of the pressure signal. The smart compression garment returned performance parameters (muscle activity and fatigue) comparable to the surface EMG. The major differences were that the EMG measured the electrical activity, whereas the pressure sensor measured the mechanical activity. As such, there was a phase shift between electrical and mechanical signals, with the electrical signals preceding the mechanical counterparts in most cases. This is specifically pronounced in high-speed cycling. The fatigue trend over the duration of the cycling exercise was clearly reflected in the fatigue parameters (FDs and median frequency) obtained from pressure and EMG signals. The fatigue parameter of the pressure signal (FD) showed a higher time dependency ( R 2 = 0.84) compared to the EMG signal. This reflects that the pressure signal puts more emphasis on the fatigue as a function of time rather than on the origin of fatigue (e.g., peripheral or central fatigue). In light of the high-speed activity results, caution should be exerted when using data obtained from EMG for biomechanical models. In contrast to EMG data, activity data obtained from FMG are considered more appropriate and accurate as an input for biomechanical modeling as they truly reflect the mechanical muscle activity. In summary, the smart compression garment based on FMG is a valid alternative to EMG-garments and provides more accurate results at high-speed activity (avoiding the electro-mechanical delay), as well as clearly measures the progress of muscle fatigue over time.

Muscle Performance Investigated With a Novel Smart Compression Garment Based on Pressure Sensor Force Myography and Its Validation Against EMG

PubMed Central

Belbasis, Aaron; Fuss, Franz Konstantin

2018-01-01

Muscle activity and fatigue performance parameters were obtained and compared between both a smart compression garment and the gold-standard, a surface electromyography (EMG) system during high-speed cycling in seven participants. The smart compression garment, based on force myography (FMG), comprised of integrated pressure sensors that were sandwiched between skin and garment, located on five thigh muscles. The muscle activity was assessed by means of crank cycle diagrams (polar plots) that displayed the muscle activity relative to the crank cycle. The fatigue was assessed by means of the median frequency of the power spectrum of the EMG signal; the fractal dimension (FD) of the EMG signal; and the FD of the pressure signal. The smart compression garment returned performance parameters (muscle activity and fatigue) comparable to the surface EMG. The major differences were that the EMG measured the electrical activity, whereas the pressure sensor measured the mechanical activity. As such, there was a phase shift between electrical and mechanical signals, with the electrical signals preceding the mechanical counterparts in most cases. This is specifically pronounced in high-speed cycling. The fatigue trend over the duration of the cycling exercise was clearly reflected in the fatigue parameters (FDs and median frequency) obtained from pressure and EMG signals. The fatigue parameter of the pressure signal (FD) showed a higher time dependency (R2 = 0.84) compared to the EMG signal. This reflects that the pressure signal puts more emphasis on the fatigue as a function of time rather than on the origin of fatigue (e.g., peripheral or central fatigue). In light of the high-speed activity results, caution should be exerted when using data obtained from EMG for biomechanical models. In contrast to EMG data, activity data obtained from FMG are considered more appropriate and accurate as an input for biomechanical modeling as they truly reflect the mechanical muscle activity. In summary, the smart compression garment based on FMG is a valid alternative to EMG-garments and provides more accurate results at high-speed activity (avoiding the electro-mechanical delay), as well as clearly measures the progress of muscle fatigue over time. PMID:29725306

Current Management of Calcific Aortic Stenosis

PubMed Central

Lindman, Brian R.; Bonow, Robert O.; Otto, Catherine M.

2014-01-01

Calcific aortic stenosis (AS) is a progressive disease with no effective medical therapy that ultimately requires aortic valve replacement (AVR) for severe valve obstruction. Echocardiography is the primary diagnostic approach to define valve anatomy, measure AS severity and evaluate the left ventricular (LV) response to chronic pressure overload. In asymptomatic patients, markers of disease progression include the degree of leaflet calcification, hemodynamic severity of stenosis, adverse LV remodeling, reduced LV longitudinal strain, myocardial fibrosis and pulmonary hypertension. The onset of symptoms portends a predictably high mortality rate unless AVR is performed. In symptomatic patients, AVR improves symptoms, improves survival and, in patients with LV dysfunction, improves systolic function. Poor outcomes after AVR are associated with low-flow low-gradient AS, severe ventricular fibrosis, oxygen dependent lung disease, frailty, advanced renal dysfunction and a high comorbidity score. However, in most patients with severe symptoms, AVR is lifesaving. Bioprosthetic valves are recommended for patients over the age of 65 years. Transcatheter AVR is now available for patients with severe comorbidities, is recommended in patients who are deemed inoperable and is a reasonable alternative to surgical AVR in high risk patients. PMID:23833296

Pressure and Friction Injuries in Primary Care.

PubMed

Phillips, Shawn; Seiverling, Elizabeth; Silvis, Matthew

2015-12-01

Pressure and friction injuries are common throughout the lifespan. A detailed history of the onset and progression of friction and pressure injuries is key to aiding clinicians in determining the underlying mechanism behind the development of the injury. Modifying or removing the forces that are creating pressure or friction is the key to both prevention and healing of these injuries. Proper care of pressure and friction injuries to the skin is important to prevent the development of infection. Patient education on positioning and ergonomics can help to prevent recurrence of pressure and friction injuries. Copyright © 2015 Elsevier Inc. All rights reserved.

Validation of High Aspect Ratio Cooling in a 89 kN (20,000 lb(sub f)) Thrust Combustion Chamber

NASA Technical Reports Server (NTRS)

Wadel, Mary F.; Meyer, Michael L.

1996-01-01

In order to validate the benefits of high aspect ratio cooling channels in a large scale rocket combustion chamber, a high pressure, 89 kN (20,000 lbf) thrust, contoured combustion chamber was tested in the NASA Lewis Research Center Rocket Engine Test Facility. The combustion chamber was tested at chamber pressures from 5.5 to 11.0 MPa (800-1600 psia). The propellants were gaseous hydrogen and liquid oxygen at a nominal mixture ratio of six, and liquid hydrogen was used as the coolant. The combustion chamber was extensively instrumented with 30 backside skin thermocouples, 9 coolant channel rib thermocouples, and 10 coolant channel pressure taps. A total of 29 thermal cycles, each with one second of steady state combustion, were completed on the chamber. For 25 thermal cycles, the coolant mass flow rate was equal to the fuel mass flow rate. During the remaining four thermal cycles, the coolant mass flow rate was progressively reduced by 5, 6, 11, and 20 percent. Computer analysis agreed with coolant channel rib thermocouples within an average of 9 percent and with coolant channel pressure drops within an average of 20 percent. Hot-gas-side wall temperatures of the chamber showed up to 25 percent reduction, in the throat region, over that of a conventionally cooled combustion chamber. Reducing coolant mass flow yielded a reduction of up to 27 percent of the coolant pressure drop from that of a full flow case, while still maintaining up to a 13 percent reduction in a hot-gas-side wall temperature from that of a conventionally cooled combustion chamber.

The Role of Compliance and Reaction Rate in Dehydration Weakening and Frictional Stability of Antigorite

NASA Astrophysics Data System (ADS)

Burdette, E.; Okazaki, K.; Hirth, G.

2017-12-01

The complicated brittle-ductile rheology of antigorite at subduction zone pressures and temperatures, resulting from its anisotropic mechanical properties, low dehydration temperature, and high water content has made interpretation of dehydration weakening problematic. Recent analyses indicate that antigorite is both ductile and brittle at high temperatures, and follows effective pressure frictional laws while dehydrating. In this study we focus on the role of rig compliance and reaction kinetics on frictional weakening and frictional stability. In addition, we correlate the evolution of mechanical behavior with AE activity at conditions within and above the thermal stability limit of antigorite. We conducted experiments at confining pressures from 0.25 GPa to 1GPa in a Griggs apparatus and modified rig compliance by including compliant components within the loading frame. We also modeled in-situ reaction progress using parameters from Sawai et al. (2013) to quantify relationships between weakening and fluid production. Without modifying the compliance, low pressure runs show stable dehydration weakening. With a modified, low compliance, results were nearly identical to stable weakening at standard compliance at 1 GPa. However, at lower pressures, many acoustic emissions were recorded at peak reaction rates during temperature ramping, with a rapid failure event occurring several minutes afterward (with the caveat that we still need to verify that AEs occur within the sample). No AEs are observed during room temperature experiments in samples that fault, nor were any observed in the high temperature experiments at conditions within the antigorite stability field - consistent with prior studies. Our results demonstrate that understanding in-situ dehydration reaction kinetics and their feedback with rheology and system compliance are key to scaling laboratory antigorite rheology to earth.

Spatially explicit risk approach for multi-hazard assessment and management in marine environment: The case study of the Adriatic Sea.

PubMed

Furlan, Elisa; Torresan, Silvia; Critto, Andrea; Marcomini, Antonio

2018-03-15

In the last few decades the health of marine ecosystems has been progressively endangered by the anthropogenic presence. Natural and human-made pressures, as well as climate change effects, are posing increasing threats on marine areas, triggering alteration of biological, chemical and physical processes. Planning of marine areas has become a challenge for decision makers involved in the design of sustainable management options. In order to address threats posed by climate drivers in combination with local to regional anthropogenic pressures affecting marine ecosystems and activities, a multi-hazard assessment methodology was developed and applied to the Adriatic Sea for the reference scenario 2000-2015. Through a four-stages process based on the consecutive analysis of hazard, exposure, vulnerability and risk the methodology allows a semi-quantitative evaluation of the relative risk from anthropogenic and natural sources to multiple endpoints, thus supporting the identification and ranking of areas and targets more likely to be at risk. Resulting output showed that the higher relative hazard scores are linked to exogenic pressures (e.g. sea surface temperature variation) while the lower ones resulted from endogenic and more localized stressors (e.g. abrasion, nutrient input). Relatively very high scores were observed for vulnerability over the whole case study for almost all the considered pressures, showing seagrasses meadows, maërl and coral beds as the most susceptible targets. The approach outlined in this study provides planners and decision makers a quick-screening tool to evaluate progress towards attaining a good environmental status and to identify marine areas where management actions and adaptation strategies would be best targeted. Moreover, by focusing on risks induced by land-based drivers, resulting output can support the design of infrastructures for reducing pressures on the sea, contributing to improve the land-sea interface management. Copyright © 2017 Elsevier B.V. All rights reserved.

Vascular surgical society of great britain and ireland: immunoglobulin A antibodies against chlamydia pneumoniae are associated with expansion of small abdominal aortic aneurysms and declining ankle blood pressure

PubMed

Lindholt; Vammen; Henneberg; Fasting

1999-05-01

BACKGROUND: The potential correlation between chronic infection with Chlamydia pneumoniae and the progression of small abdominal aortic aneurysms (AAAs) and lower limb atherosclerosis was studied. METHODS: Mass screening for AAA was carried out in outdoor clinics at all hospitals in the county. Some 139 men (aged 65-73 years) with a 3.0-4.9-cm AAA were followed prospectively for 1-3 (mean 2.7) years. Initially, an interview and examination was performed, and blood samples were taken. RESULTS: Some 62 per cent (53-71 per cent) had an immunoglobulin (Ig) A level of 40 or more, or an IgG level of 64 or above. Some 83 per cent (74-93 per cent) had an IgA level of 20 or more, or an IgG level of 32 or more. Men with an IgA level of 20 or more had 51 per cent greater AAA expansion and men with an IgA level of 40 or above had 24 per cent more expansion. An IgA level of 20 or more, or IgA of 40 or greater, were significant independent predictors of AAA expansion adjusted for age, smoking, initial AAA size, steroid treatment, diastolic blood pressure, pulmonary function and other plasma factors. The ankle blood pressure index (ABI) of the IgA-seropositive men decreased 11 per cent, while the ABI decreased by 5 per cent among IgA-seronegative men (P < 0.05). The significant difference persisted after adjusting for age, smoking, initial systolic ankle blood pressure, initial brachial systolic or diastolic blood pressure, but disappeared after adjusting for low-density lipoprotein (LDL) levels. CONCLUSION: A high proportion of men with a small AAA have signs of chronic C. pneumoniae infection. The progression of AAAs and lower limb atherosclerosis seems to be correlated to chronic infection with C. pneumoniae.

Development of Hybrid Sensor Arrays for Sensor Arrays for Simultaneous Measurement of Pressure and Shear Stress Distribution

NASA Technical Reports Server (NTRS)

2000-01-01

This document reports on the progress in developing hybrid sensors for the simultaneous measurement of pressure and shear stress. The key feature for the success of the proposed hybrid sensor array is the ability to deposit Cu-Ni alloy with proper composition (55 - 45) on a silicon wafer to form a strain gage. This alloy strain gage replaces the normally used Si strain gages in MEMS, which are highly nonlinear and temperature dependent. The copper nickel, with proper composition (55 - 45), was successfully deposited on a silicon wafer with a few trials during this period of the project. Pictures of the Cu-Ni alloy strain gage and the x-ray spectra indicating the composition are shown. The planned tests are also reviewed.

Combustion of LOX with H2(sub g) under subcritical, critical, and supercritical conditions (Task 1) and experimental observation of dense spray and mixing of impinging jets (Task 2)

NASA Technical Reports Server (NTRS)

Kuo, K. K.; Hsieh, W. H.; Cheung, F. B.; Yang, A. S.; Brown, J. J.; Woodward, R. D.; Kline, M. C.; Burch, R. L.

1992-01-01

The objective was to achieve a better understanding of the combustion processes of liquid oxygen and gaseous hydrogen under broad range of pressure covering subcritical, critical, and supercritical conditions. The scope of the experimental work falls into the following areas: (1) design of the overall experimental setup; (2) modification of an existing windowed high pressure chamber; (3) design of the LOX feeding system; (4) provision of the safety features in the test rig design; (5) LOX cleanliness requirements; (6) cold shock testing; (7) implementation of data acquisition systems; (8) preliminary tests for system checkout; (9) modification of LOX feeding system; and (10) evaporation tests. Progress in each area is discussed.

Vapor cycle energy system for implantable circulatory assist devices. Annual progress report Jul 1974--Jun 1975. [Tidal regenerator engine

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

Hagen, K.G.

1975-06-01

The report describes the development status of a heart assist system driven by a nuclear fueled, electronically controlled vapor cycle engine termed the tidal regenerator engine (TRE). The TRE pressurization (typically from 5-160 psia) is controlled by a torque motor coupled to a displacer. The electrical power for the sensor, electronic logic and actuator is provided by a thermoelectric module interposed between the engine superheater and boiler. The TRE is direct coupled to an assist blood pump which also acts as a blood-cooled heat exchanger, pressure-volume transformer and sensor for the electronic logic. Engine efficiencies in excess of 14% havemore » been demonstrated. Efficiency values as high as 13% have been achieved to date.« less

Microseismic and deformation imaging of hydraulic fracture growth and geometry in the C sand interval, GRI/DOE M-Site project

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

Warpinski, N.R.; Uhl, J.E.; Engler, B.P.

Six hydraulic-fracture injections into a fluvial sandstone at a depth of 4300 ft were monitored with multi-level tri-axial seismic receivers in two wells and an inclinometer array in one well, resulting in maps of the growth and final geometry of each fracture injection. These diagnostic images show the progression of height and length growth with fluid volume, rate and viscosity. Complexities associated with shut downs and high treatment pressures can be observed. Validation of the seismic geometry was made with the inclinometers and diagnostic procedures in an intersecting well. Fracture information related to deformation, such as fracture closure pressure, residualmore » widths, and final prop distribution, were obtained from the inclinometer data.« less

How does yeast respond to pressure?

PubMed

Fernandes, P M B

2005-08-01

The brewing and baking yeast Saccharomyces cerevisiae has been used as a model for stress response studies of eukaryotic cells. In this review we focus on the effect of high hydrostatic pressure (HHP) on S. cerevisiae. HHP exerts a broad effect on yeast cells characteristic of common stresses, mainly associated with protein alteration and lipid bilayer phase transition. Like most stresses, pressure induces cell cycle arrest. Below 50 MPa (500 atm) yeast cell morphology is unaffected whereas above 220 MPa wild-type cells are killed. S. cerevisiae cells can acquire barotolerance if they are pretreated with a sublethal stress due to temperature, ethanol, hydrogen peroxide, or pressure. Nevertheless, pressure only leads to protection against severe stress if, after pressure pretreatment, the cells are also re-incubated at room pressure. We attribute this effect to the inhibition of the protein synthesis apparatus under HHP. The global genome expression analysis of S. cerevisiae cells submitted to HHP revealed a stress response profile. The majority of the up-regulated genes are involved in stress defense and carbohydrate metabolism while most repressed genes belong to the cell cycle progression and protein synthesis categories. However, the signaling pathway involved in the pressure response is still to be elucidated. Nitric oxide, a signaling molecule involved in the regulation of a large number of cellular functions, confers baroprotection. Furthermore, S. cerevisiae cells in the early exponential phase submitted to 50-MPa pressure show induction of the expression level of the nitric oxide synthase inducible isoform. As pressure becomes an important biotechnological tool, studies concerning this kind of stress in microorganisms are imperative.

[Contribution of hemodynamic disturbances in magistral vessels to optic neuropathy progression and ocular tension changes in endocrine ophthalmopathy].

PubMed

Likhvantseva, V G; Kharlap, S I; Korosteleva, E V; Solomatina, M V; Mel'nikova, M V; Budanova, S V; Regeb, A Ben; Vygodin, V A

2015-01-01

to investigate the contribution of various hemodynamic disturbances in magistral vessels to optic neuropathy (ON) progression and ocular tension changes in endocrine ophthalmopathy (EOP). A total of 39 patients (78 eyes) with subclinical EOP (clinical activity score, CAS ≤ 2) associated with Graves' disease (n = 32, 64 eyes) or autoimmune thyroiditis (n = 7, 14 eyes) were examined. Orbit echography was performed in all patients. Blood flow was assessed with a Voluson 730 PRO ultrasound diagnostic system ("Kretz", Austria) in triplex mode (B-scan, color Doppler flow mapping in combination with pulse-wave Doppler). Thus obtained hemodynamic parameters in ophthalmic artery, central retinal artery (CRA), central retinal vein (CRV), short posterior ciliary arteries (SPCA), and long posterior ciliary arteries (LPCA) were analyzed. To reveal the role of hemodynamic disturbances in the above mentioned vessels in ON progression and eye pressure maintenance, the patients were divided into 7 groups. Only those eyes, whose peripheral indices were increased by more than 25% of normal values and diastolic blood flow decreased by not less than 25%, were selected for further study. Intraocular pressure changes were evaluated by group mean (Mmean = M ± m mmHg), optic neuropathy progression--by the difference in group mean depth (dB) and number of scotomas between the first and the last visit (6 months of observation). In almost all types of perfusion disturbances, the resultant chronic ocular ischemia causes a decrease in IOP. The only exception, as shown, is simultaneous involvement of CRA, SPCA, and LPCA. The level of blood flow disturbance determines the severity of qualitative and quantitative changes in eyes with EOP-associated ON. The rate of ON progression directly correlates with baseline IOP values on day zero. Long-lasting chronic impairment of blood supply of the eyeball leads to reduction in ocular tension and progression of optic neuropathy. Combined perfusion disturbances in CRA and LPCA as well as in CRA, LPCA, and SPCA can be considered a high-risk factor, while SPCA and/or LPCA involvement--a moderate-risk factor.

Inhibition on Apoptosis Induced by Elevated Hydrostatic Pressure in Retinal Ganglion Cell-5 via Laminin Upregulating β1-integrin/Focal Adhesion Kinase/Protein Kinase B Signaling Pathway.

PubMed

Li, Yi; Chen, Yan-Ming; Sun, Ming-Ming; Guo, Xiao-Dan; Wang, Ya-Chen; Zhang, Zhong-Zhi

2016-04-20

Glaucoma is a progressive optic neuropathy characterized by degeneration of neurons due to loss of retinal ganglion cells (RGCs). High intraocular pressure (HIOP), the main risk factor, causes the optic nerve damage. However, the precise mechanism of HIOP-induced RGC death is not yet completely understood. This study was conducted to determine apoptosis of RGC-5 cells induced by elevated hydrostatic pressures, explore whether laminin is associated with apoptosis under pressure, whether laminin can protect RGCs from apoptosis and affirm the mechanism that regulates the process of RGCs survival. RGC-5 cells were exposed to 0, 20, 40, and 60 mmHg in a pressurized incubator for 6, 12, and 24 h, respectively. The effect of elevated hydrostatic pressure on RGC-5 cells was measured by Annexin V-fluorescein isothiocyanate/propidium iodide staining, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, and Western blotting of cleaved caspase-3 protein. Location and expression of laminin were detected by immunofluorescence. The expression of β1-integrin, phosphorylation of focal adhesion kinase (FAK) and protein kinase B (PKB, or AKT) were investigated with real-time polymerase chain reaction and Western blotting analysis. Elevated hydrostatic pressure induced apoptosis in cultured RGC-5 cells. Pressure with 40 mmHg for 24 h induced a maximum apoptosis. Laminin was declined in RGC-5 cells after exposing to 40 mmHg for 24 h. After pretreating with laminin, RGC-5 cells survived from elevated pressure. Furthermore, β1-integrin and phosphorylation of FAK and AKT were increased compared to 40 mmHg group. The data show apoptosis tendency of RGC-5 cells with elevated hydrostatic pressure. Laminin can protect RGC-5 cells against high pressure via β1-integrin/FAK/AKT signaling pathway. These results suggest that the decreased laminin of RGC-5 cells might be responsible for apoptosis induced by elevated hydrostatic pressure, and laminin or activating β1-integrin/FAK/AKT pathway might be potential treatments to prevent RGC loss in glaucomatous optic neuropathy.

Inhibition on Apoptosis Induced by Elevated Hydrostatic Pressure in Retinal Ganglion Cell-5 via Laminin Upregulating β1-integrin/Focal Adhesion Kinase/Protein Kinase B Signaling Pathway

PubMed Central

Li, Yi; Chen, Yan-Ming; Sun, Ming-Ming; Guo, Xiao-Dan; Wang, Ya-Chen; Zhang, Zhong-Zhi

2016-01-01

Background: Glaucoma is a progressive optic neuropathy characterized by degeneration of neurons due to loss of retinal ganglion cells (RGCs). High intraocular pressure (HIOP), the main risk factor, causes the optic nerve damage. However, the precise mechanism of HIOP-induced RGC death is not yet completely understood. This study was conducted to determine apoptosis of RGC-5 cells induced by elevated hydrostatic pressures, explore whether laminin is associated with apoptosis under pressure, whether laminin can protect RGCs from apoptosis and affirm the mechanism that regulates the process of RGCs survival. Methods: RGC-5 cells were exposed to 0, 20, 40, and 60 mmHg in a pressurized incubator for 6, 12, and 24 h, respectively. The effect of elevated hydrostatic pressure on RGC-5 cells was measured by Annexin V-fluorescein isothiocyanate/propidium iodide staining, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, and Western blotting of cleaved caspase-3 protein. Location and expression of laminin were detected by immunofluorescence. The expression of β1-integrin, phosphorylation of focal adhesion kinase (FAK) and protein kinase B (PKB, or AKT) were investigated with real-time polymerase chain reaction and Western blotting analysis. Results: Elevated hydrostatic pressure induced apoptosis in cultured RGC-5 cells. Pressure with 40 mmHg for 24 h induced a maximum apoptosis. Laminin was declined in RGC-5 cells after exposing to 40 mmHg for 24 h. After pretreating with laminin, RGC-5 cells survived from elevated pressure. Furthermore, β1-integrin and phosphorylation of FAK and AKT were increased compared to 40 mmHg group. Conclusions: The data show apoptosis tendency of RGC-5 cells with elevated hydrostatic pressure. Laminin can protect RGC-5 cells against high pressure via β1-integrin/FAK/AKT signaling pathway. These results suggest that the decreased laminin of RGC-5 cells might be responsible for apoptosis induced by elevated hydrostatic pressure, and laminin or activating β1-integrin/FAK/AKT pathway might be potential treatments to prevent RGC loss in glaucomatous optic neuropathy. PMID:27064044

High-Intensity Progressive Resistance Training Increases Strength With No Change in Cardiovascular Function and Autonomic Neural Regulation in Older Adults.

PubMed

Kanegusuku, Hélcio; Queiroz, Andréia C; Silva, Valdo J; de Mello, Marco T; Ugrinowitsch, Carlos; Forjaz, Cláudia L

2015-07-01

The effects of high-intensity progressive resistance training (HIPRT) on cardiovascular function and autonomic neural regulation in older adults are unclear. To investigate this issue, 25 older adults were randomly divided into two groups: control (CON, N = 13, 63 ± 4 years; no training) and HIPRT (N = 12, 64 ± 4 years; 2 sessions/week, 7 exercises, 2–4 sets, 10–4 RM). Before and after four months, maximal strength, quadriceps cross-sectional area (QCSA), clinic and ambulatory blood pressures (BP), systemic hemodynamics, and cardiovascular autonomic modulation were measured. Maximal strength and QCSA increased in the HIPRT group and did not change in the CON group. Clinic and ambulatory BP, cardiac output, systemic vascular resistance, stroke volume, heart rate, and cardiac sympathovagal balance did not change in the HIPRT group or the CON group. In conclusion, HIPRT was effective at increasing muscle mass and strength without promoting changes in cardiovascular function or autonomic neural regulation.

Department of Defense Weapon System Acquisition Policy: A System Dynamics Model and Analysis.

DTIC Science & Technology

1982-09-01

dimensionless) PRPRD = Perceived Pressure for R&D (dimensionless) PU - Programs in Progress (programs) RPRD - Raw Pressure for R&D (dimensionless) TDPP - Time...ECAP) TH9 Pressure Ra Pressure_.- for Acquisition ( TDPP ) TH25 4for Acquisition (DPFAO) TH22D (DPPFAO) TH21 US Intelligence \\ - 7 Delay Time / efense...DIBP, DPPFAQ. K) TH22 A CPPFAG.K=DLINF3(RPFAG.KTCPP) TH23 A CPFAQ.K=MAX (DIBPCPPFAQ.K) TH24 C TDPP =12 TH25 C TCPP-24 TH26 CPFAQ Congressional Pressure

Progressive Fracture and Damage Tolerance of Composite Pressure Vessels

NASA Technical Reports Server (NTRS)

Chamis, Christos C.; Gotsis, Pascal K.; Minnetyan, Levon

1997-01-01

Structural performance (integrity, durability and damage tolerance) of fiber reinforced composite pressure vessels, designed for pressured shelters for planetary exploration, is investigated via computational simulation. An integrated computer code is utilized for the simulation of damage initiation, growth, and propagation under pressure. Aramid fibers are considered in a rubbery polymer matrix for the composite system. Effects of fiber orientation and fabrication defect/accidental damages are investigated with regard to the safety and durability of the shelter. Results show the viability of fiber reinforced pressure vessels as damage tolerant shelters for planetary colonization.

[A case of ring melanoma found while treating traumatic glaucoma].

PubMed

Manabe, Kazuyo; Jo, Nobuo; Tateno, Hiroko; Shishidon, Nami; Takahashi, Kanji; Iwashita, Kenshiro; Isei, Taiki; Ohe, Chisato; Sakaida, Noriko; Uemura, Yoshiko

2013-04-01

Ring melanoma, a malignant melanoma which infiltrates over 180 degrees degrees of the ciliary body is very rare in Japan. We report a case of ring melanoma found while treating treatment of traumatic glaucoma with an ultrasound biomicroscope (UBM). A 44-year old woman presented with high intraocular pressure after blunt trauma in her left eye. Best-corrected visual acuity OS was 1.2, and intraocular pressure was 30 mmHg. Gonioscopy showed about 180 degrees of the angle recession. Intraocular pressure was difficult to control in spite of anti-glaucoma drug treatment. Rapid progression of iris elevation and 360 degrees thickening of the ciliary body were detected by UBM. We detected atypical cells with melanine granules in the aqueous fluid and positive findings in PET-CT, leading to a diagnosis of ciliary body malignant melanoma. Consequently we enucleated the left eye. The histopathological diagnosis was ring melanoma. Ring melanoma is an important element in the differential diagnosis for untreatable secondary glaucoma.

High temperature pyrolysis of vinylacetylene

NASA Astrophysics Data System (ADS)

Braun-Unkhoff, M.; Kurz, A.; Frank, P.

1990-07-01

The thermal decomposition of vinylacetylene has been studied behind reflected shock waves in the temperature range 1350-1870 K at total pressures between 1.7 and 7.4 bar. Initial concentrations of the hydrogen in argon ranged between 1 to 300 ppm. The following species were measured: H-atoms by ARAS, C2H2, C4H2 and C4H4 by molecular vuv-absorption. The combination of very low initial concentrations with a sensitive detection technique allowed to perform the experiments under conditions where only very few elementary reaction steps determine the progress of reaction. It was found that C4H4 decomposes simultaneously into different product channels: C4H4→C2H2+C2H2 k1a=3.4ṡ1013 exp(-38820/T) s-1 C4H4+Ar→C4H3+H+Ar k1b=1.1ṡ1020exp(-49990/T) cm3 mol-1 s-1 C4H4→C4H2+H2 k1c=1.3ṡ1015exp(-47670/T) s-1. From variation of the total pressure it has been deduced that reaction pathways R1a and R1c proceed with rates not far from the high-pressure limiting values and that reaction R1b proceeds close to the low-pressure limiting rate constant values.

Air filtration in the free molecular flow regime: a review of high-efficiency particulate air filters based on carbon nanotubes.

PubMed

Li, Peng; Wang, Chunya; Zhang, Yingying; Wei, Fei

2014-11-01

Air filtration in the free molecular flow (FMF) regime is important and challenging because a higher filtration efficiency and lower pressure drop are obtained when the fiber diameter is smaller than the gas mean free path in the FMF regime. In previous studies, FMF conditions have been obtained by increasing the gas mean free path through reducing the pressure and increasing the temperature. In the case of carbon nanotubes (CNTs) with nanoscale diameters, it is possible to filtrate in the FMF regime under normal conditions. This paper reviews recent progress in theoretical and experimental studies of air filtration in the FMF regime. Typical structure models of high-efficiency particulate (HEPA) air filters based on CNTs are introduced. The pressure drop in air filters operated in the FMF regime is less than that predicted by the conventional air filtration theory. The thinnest HEPA filters fabricated from single-walled CNT films have an extremely low pressure drop. CNT air filters with a gradient nanostructure are shown to give a much better filtration performance in dynamic filtration. CNT air filters with a hierarchical structure and an agglomerated CNT fluidized bed air filter are also introduced. Finally, the challenges and opportunities for the application of CNTs in air filtration are discussed. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A rabbit model of progressive chronic right ventricular pressure overload.

PubMed

Roldan Ramos, Sara; Pieles, Guido; Hui, Wei; Slorach, Cameron; Redington, Andrew N; Friedberg, Mark K

2018-04-01

Right ventricular (RV) failure from increased pressure loading is a frequent consequence of acquired and congenital heart diseases. However, the mechanisms involved in their pathophysiology are still unclear, and few data exist on RV pressure-loading models and early versus late effects on RV and left ventricular responses. We characterized a rabbit model of chronic RV pressure overload and early-late effects on biventricular function. Twenty-one New Zealand white rabbits were randomized into 3 groups: (i) sham, (ii) pulmonary artery (PA) banding (PAB) for 3 weeks (PAB3W) and (iii) PAB for 6 weeks (PAB6W). Progressive RV pressure overload was created by serial band inflation using an adjustable device. Molecular, echocardiographic and haemodynamic studies were performed. RV pressure overload was achieved with clinical manifestations of RV failure. Heart and liver weights were significantly higher after PAB. PAB-induced echocardiographic ventricular remodelling increased wall thickness and stress and ventricular dilation. Cardiac output (ml/min) (sham 172.4 ± 42.86 vs PAB3W 103.1 ± 23.14 vs PAB6W 144 ± 60.9, P = 0.0027) and systolic and diastolic functions decreased; with increased RV end-systolic and end-diastolic pressures (mmHg) (sham 1.6 ± 0.66 vs PAB3W 3.9 ± 1.8 vs PAB6W 5.2 ± 2.2, P = 0.0103), despite increased contractility [end-systolic pressure-volume relationship (mmHg/ml), sham 3.76 ± 1.76 vs PAB3W 12.21 ± 3.44 vs PAB6W 19.4 ± 6.88, P < 0.0001]. Functional parameters further worsened after PAB6W versus PAB3W. LV contractility increased in both the PAB groups, despite worsening of other invasive measures of systolic and diastolic functions. We describe a novel, unique model of chronic RV pressure overload leading to early biventricular dysfunction and fibrosis with further progression at 6 weeks. These findings can aid in guiding management.

Hard time to be parents? Sea urchin fishery shifts potential reproductive contribution of population onto the shoulders of the young adults.

PubMed

Loi, Barbara; Guala, Ivan; Pires da Silva, Rodrigo; Brundu, Gianni; Baroli, Maura; Farina, Simone

2017-01-01

In Sardinia, as in other regions of the Mediterranean Sea, sustainable fisheries of the sea urchin Paracentrotus lividus have become a necessity. At harvesting sites, the systematic removal of large individuals (diameter ≥ 50 mm) seriously compromises the biological and ecological functions of sea urchin populations. Specifically, in this study, we compared the reproductive potential of the populations from Mediterranean coastal areas which have different levels of sea urchin fishing pressure. The areas were located at Su Pallosu Bay, where pressure is high and Tavolara-Punta Coda Cavallo, a marine protected area where sea urchin harvesting is low. Reproductive potential was estimated by calculating the gonadosomatic index (GSI) from June 2013 to May 2014 both for individuals of commercial size (diameter without spines, TD ≥ 50 mm) and the undersized ones with gonads (30 ≤ TD < 40 mm and 40 ≤ TD < 50 mm). Gamete output was calculated for the commercial-size class and the undersized individuals with fertile gonads (40 ≤ TD < 50 mm) in relation to their natural density (gamete output per m 2 ). The reproductive potential of populations was slightly different at the beginning of the sampling period but it progressed at different rates with an early spring spawning event in the high-pressure zone and two gamete depositions in early and late spring in the low-pressure zone. For each fertile size class, GSI values changed significantly during the year of our study and between the two zones. Although the multiple spawning events determined a two-fold higher total gamete output of population (popTGO) in the low-pressure zone, the population mean gamete output (popMGO) was similar in the two zones. In the high-pressure zone, the commercial-sized individuals represented approximatively 5% of the population, with almost all the individuals smaller than 60 mm producing an amount of gametes nearly three times lower than the undersized ones. Conversely, the high density of the undersized individuals released a similar amount of gametes to the commercial-size class in the low-pressure zone. Overall, the lack of the commercial-size class in the high-pressure zone does not seem to be very alarming for the self-supporting capacity of the population, and the reproductive potential contribution seems to depend more on the total density of fertile sea urchins than on their size. However, since population survival in the high-pressure zone is supported by the high density of undersized sea urchins between 30 and 50 mm, management measures should be addressed to maintain these sizes and to shed light on the source of the larval supply.

Hard time to be parents? Sea urchin fishery shifts potential reproductive contribution of population onto the shoulders of the young adults

PubMed Central

Guala, Ivan; Pires da Silva, Rodrigo; Brundu, Gianni; Baroli, Maura; Farina, Simone

2017-01-01

Background In Sardinia, as in other regions of the Mediterranean Sea, sustainable fisheries of the sea urchin Paracentrotus lividus have become a necessity. At harvesting sites, the systematic removal of large individuals (diameter ≥ 50 mm) seriously compromises the biological and ecological functions of sea urchin populations. Specifically, in this study, we compared the reproductive potential of the populations from Mediterranean coastal areas which have different levels of sea urchin fishing pressure. The areas were located at Su Pallosu Bay, where pressure is high and Tavolara-Punta Coda Cavallo, a marine protected area where sea urchin harvesting is low. Methods Reproductive potential was estimated by calculating the gonadosomatic index (GSI) from June 2013 to May 2014 both for individuals of commercial size (diameter without spines, TD ≥ 50 mm) and the undersized ones with gonads (30 ≤ TD < 40 mm and 40 ≤ TD < 50 mm). Gamete output was calculated for the commercial-size class and the undersized individuals with fertile gonads (40 ≤ TD < 50 mm) in relation to their natural density (gamete output per m2). Results The reproductive potential of populations was slightly different at the beginning of the sampling period but it progressed at different rates with an early spring spawning event in the high-pressure zone and two gamete depositions in early and late spring in the low-pressure zone. For each fertile size class, GSI values changed significantly during the year of our study and between the two zones. Although the multiple spawning events determined a two-fold higher total gamete output of population (popTGO) in the low-pressure zone, the population mean gamete output (popMGO) was similar in the two zones. In the high-pressure zone, the commercial-sized individuals represented approximatively 5% of the population, with almost all the individuals smaller than 60 mm producing an amount of gametes nearly three times lower than the undersized ones. Conversely, the high density of the undersized individuals released a similar amount of gametes to the commercial-size class in the low-pressure zone. Discussion Overall, the lack of the commercial-size class in the high-pressure zone does not seem to be very alarming for the self-supporting capacity of the population, and the reproductive potential contribution seems to depend more on the total density of fertile sea urchins than on their size. However, since population survival in the high-pressure zone is supported by the high density of undersized sea urchins between 30 and 50 mm, management measures should be addressed to maintain these sizes and to shed light on the source of the larval supply. PMID:28289567

Direct and Selective Synthesis of Hydrogen Peroxide over Palladium-Tellurium Catalysts at Ambient Pressure.

PubMed

Tian, Pengfei; Xu, Xingyan; Ao, Can; Ding, Doudou; Li, Wei; Si, Rui; Tu, Weifeng; Xu, Jing; Han, Yi-Fan

2017-09-11

Highly selective hydrogen peroxide (H 2 O 2 ) synthesis directly from H 2 and O 2 is a strongly desired reaction for green processes. Herein a highly efficient palladium-tellurium (Pd-Te/TiO 2 ) catalyst with a selectivity of nearly 100 % toward H 2 O 2 under mild conditions (283 K, 0.1 MPa, and a semi-batch continuous flow reactor) is reported. The size of Pd particles was remarkably reduced from 2.1 nm to 1.4 nm with the addition of Te. The Te-modified Pd surface could significantly weaken the dissociative activation of O 2 , leading to the non-dissociative hydrogenation of O 2 . Density functional theory calculations illuminated the critical role of Te in the selective hydrogenation of O 2 , in that the active sites composed of Pd and Te could significantly restrain side reactions. This work has made significant progress on the development of high-selectivity catalysts for the direct synthesis of H 2 O 2 at ambient pressure. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Heavy hydrocarbon main injector technology

NASA Technical Reports Server (NTRS)

Fisher, S. C.; Arbit, H. A.

1988-01-01

One of the key components of the Advanced Launch System (ALS) is a large liquid rocket, booster engine. To keep the overall vehicle size and cost down, this engine will probably use liquid oxygen (LOX) and a heavy hydrocarbon, such as RP-1, as propellants and operate at relatively high chamber pressures to increase overall performance. A technology program (Heavy Hydrocarbon Main Injector Technology) is being studied. The main objective of this effort is to develop a logic plan and supporting experimental data base to reduce the risk of developing a large scale (approximately 750,000 lb thrust), high performance main injector system. The overall approach and program plan, from initial analyses to large scale, two dimensional combustor design and test, and the current status of the program are discussed. Progress includes performance and stability analyses, cold flow tests of injector model, design and fabrication of subscale injectors and calorimeter combustors for performance, heat transfer, and dynamic stability tests, and preparation of hot fire test plans. Related, current, high pressure, LOX/RP-1 injector technology efforts are also briefly discussed.

An Efficient Modelling Approach for Prediction of Porosity Severity in Composite Structures

NASA Technical Reports Server (NTRS)

Bedayat, Houman; Forghani, Alireza; Hickmott, Curtis; Roy, Martin; Palmieri, Frank; Grimsley, Brian; Coxon, Brian; Fernlund, Goran

2017-01-01

Porosity, as a manufacturing process-induced defect, highly affects the mechanical properties of cured composites. Multiple phenomena affect the formation of porosity during the cure process. Porosity sources include entrapped air, volatiles and off-gassing as well as bag and tool leaks. Porosity sinks are the mechanisms that contribute to reducing porosity, including gas transport, void shrinkage and collapse as well as resin flow into void space. Despite the significant progress in porosity research, the fundamentals of porosity in composites are not yet fully understood. The highly coupled multi-physics and multi-scale nature of porosity make it a complicated problem to predict. Experimental evidence shows that resin pressure history throughout the cure cycle plays an important role in the porosity of the cured part. Maintaining high resin pressure results in void shrinkage and collapse keeps volatiles in solution thus preventing off-gassing and bubble formation. This study summarizes the latest development of an efficient FE modeling framework to simulate the gas and resin transport mechanisms that are among the major phenomena contributing to porosity.

Hydraulic Fracture Induced Seismicity During A Multi-Stage Pad Completion in Western Canada: Evidence of Activation of Multiple, Parallel Faults

NASA Astrophysics Data System (ADS)

Maxwell, S.; Garrett, D.; Huang, J.; Usher, P.; Mamer, P.

2017-12-01

Following reports of injection induced seismicity in the Western Canadian Sedimentary Basin, regulators have imposed seismic monitoring and traffic light protocols for fracturing operations in specific areas. Here we describe a case study in one of these reservoirs, the Montney Shale in NE British Columbia, where induced seismicity was monitored with a local array during multi-stage hydraulic fracture stimulations on several wells from a single drilling pad. Seismicity primarily occurred during the injection time periods, and correlated with periods of high injection rates and wellhead pressures above fracturing pressures. Sequential hydraulic fracture stages were found to progressively activate several parallel, critically-stressed faults, as illuminated by multiple linear hypocenter patterns in the range between Mw 1 and 3. Moment tensor inversion of larger events indicated a double-couple mechanism consistent with the regional strike-slip stress state and the hypocenter lineations. The critically-stressed faults obliquely cross the well paths which were purposely drilled parallel to the minimum principal stress direction. Seismicity on specific faults started and stopped when fracture initiation points of individual injection stages were proximal to the intersection of the fault and well. The distance ranges when the seismicity occurs is consistent with expected hydraulic fracture dimensions, suggesting that the induced fault slip only occurs when a hydraulic fracture grows directly into the fault and the faults are temporarily exposed to significantly elevated fracture pressures during the injection. Some faults crossed multiple wells and the seismicity was found to restart during injection of proximal stages on adjacent wells, progressively expanding the seismogenic zone of the fault. Progressive fault slip is therefore inferred from the seismicity migrating further along the faults during successive injection stages. An accelerometer was also deployed close to the pad operations providing information about the local ground motion at near offsets, although no ground motion was recorded that exceeds the minimum levels requiring mandatory reporting to the regulator.

Excessive variability in systolic blood pressure that is self-measured at home exacerbates the progression of brain white matter lesions and cognitive impairment in the oldest old.

PubMed

Liu, Zhendong; Zhao, Yingxin; Zhang, Hua; Chai, Qiang; Cui, Yi; Diao, Yutao; Xiu, Jianchao; Sun, Xiaolin; Jiang, Guosheng

2016-04-01

To investigate the effects of variability in self-measured systolic blood pressure at home on the progression of cognitive impairment and white matter lesions in the oldest old. Between April 2009 and October 2009, 248 oldest old aged 80 years or older were eligibly enrolled from geriatric practices and community-dwelling areas of Shandong, China. Self-measured blood pressure at home (HBP) was measured for 7 consecutive days at the baseline, and the Mini-Mental State Examination (MMSE) score and brain white matter hyperintensities (WMH) were assessed at the baseline and during the final follow-up visit. Variability in systolic HBP was evaluated using coefficient of variation (CV) in serial daily systolic HBP measurements of the last 6 consecutive days. After an average of 2.3 years of follow-up visits, 232 oldest old were included in and 16 were excluded from the analysis. The MMSE score declined -4.76 (interquartile ranges: -10.71, -0.83) %, the periventricular WMH, deep WMH, total WMH and WMH fraction increased 16.46 (s.d.: 6.72)%, 10.05 (s.d.: 6.40)%, 14.69 (s.d.: 6.07)% and 15.95 (s.d.: 6.32)%, respectively, in the total oldest old. A declined percentage of the MMSE score and increased percentages of the periventricular WMH, deep WMH, total WMH and WMH fraction in the high group divided by tertile of the CV of the systolic HBP at baseline were greater than those in the low group (P<0.05). The significant differences were retained after adjusting for covariates, including the MMSE score, periventricular WMH, deep WMH and WMH fraction at the baseline (P<0.05). Excessive variability in self-measured systolic HBP exacerbates the progression of cognitive impairment and brain white matter lesions in the oldest old.

Head-to-cervix force: an important physiological variable in labour. 1. The temporal relation between head-to-cervix force and intrauterine pressure during labour.

PubMed

Allman, A C; Genevier, E S; Johnson, M R; Steer, P J

1996-08-01

To investigate the relation between the rise in intrauterine pressure and rise in fetal head to cervix force in normal, slow and induced labour. Prospective observational study. The labour ward of a London teaching hospital. Forty patients were recruited from the antenatal clinic and labour ward of a West London Hospital. Five had normal onset and progression of labour, 14 had slow progression of labour and 21 had induced onset of labour. Intrauterine pressure and head-to-cervix force was measured simultaneously using an intrauterine pressure catheter and a specially designed four sensor head-to-cervix force probe. For each contraction of each labour, scattergrams of force by pressure were plotted. Three patterns were observed. When the rise in pressure preceded the rise in force, a positive 'loop' was generated. When the rise in pressure and force occurred simultaneously a linear pattern was generated (a neutral 'loop'). When the rise in pressure lags the rise in force, a negative 'loop' was generated. In normally progressive labour the distribution of loops was 29.1%, 22.6% and 48.3%, respectively, in slow labour the distribution was 26.1%, 14.1% and 59.8% and in induced labour the distribution was 33.8%, 14.4% and 51.8%. These distributions were not statistically different. However, a higher proportion of negative loops was observed in labours augmented with oxytocin compared to those receiving no oxytocin (MW-U = 87, P = 0.036). No differences were observed comparing parity, use of PGE2, epidural analgesia, or mode of delivery. Contraction frequency (number/10 minutes) was inversely correlated to the percentage of negative loops (rs = -0.34, P = 0.033) and positively correlated with percentage of positive loops (rs = 0.36, P = 0.027). This is the first report of the temporal relation between intrauterine pressure and head-to-cervix force in labour. The most common pattern is that the rise in pressure lags the rise in force, suggesting that a seal has to be created between the fetal head and cervix before a rise in pressure can occur. When oxytocin is given in labour, a higher proportion of loops are negative indicating that there is poor application of the fetal head and cervix in a greater proportion of contractions.

Antagonism of scavenger receptor CD36 by 5A peptide prevents chronic kidney disease progression in mice independent of blood pressure regulation

PubMed Central

Souza, Ana Carolina P.; Bocharov, Alexander V.; Baranova, Irina; Vishnyakova, Tatyana; Huang, Yuning G.; Wilkins, Kenneth J.; Hu, Xuzhen; Street, Jonathan M.; Alvarez-Prats, Alejandro; Mullick, Adam E.; Patterson, Amy P.; Remaley, Alan; Eggerman, Thomas L.; Yuen, Peter S.T.; Star, Robert A.

2016-01-01

Scavenger receptor CD36 participates in lipid metabolism and inflammatory pathways important for cardiovascular disease and chronic kidney disease (CKD). Few pharmacological agents are available to slow the progression of CKD. However, apolipoprotein AI-mimetic peptide 5A antagonizes CD36 in vitro. To test the efficacy of 5A, and to test the role of CD36 during CKD, we compared wild type to CD36 knockout mice and wild type mice treated with 5A, in a progressive CKD model that resembles human disease. Knockout and 5A-treated wild type mice were protected from CKD progression without changes in blood pressure and had reductions in cardiovascular risk surrogate markers that are associated with CKD. Treatment with 5A did not further protect CD36 knockout mice from CKD progression, implicating CD36 as its main site of action. In a separate model of kidney fibrosis, 5A-treated wild type mice had less macrophage infiltration and interstitial fibrosis. Peptide 5A exerted anti-inflammatory effects in the kidney and decreases renal expression of inflammasome genes. Thus, CD36 is a new therapeutic target for CKD and its associated cardiovascular risk factors. Peptide 5A may be a promising new agent to slow CKD progression. PMID:26994575

Research on high speed drilling technology and economic integration evaluation in Oilfield

NASA Astrophysics Data System (ADS)

Wang, Kun; Ni, Hongjian; Cheng, Na; Song, Jingbo

2018-01-01

The carbonate reservoir in the oilfield mainly formed in Ordovician System and Carboniferous System. The geology here is very complicated, with high heterogeneity. It gets much more difficult to control the well deflection in Permian system so that high accident ratio could be expected. The buried depth of the reservoir is large, normally 4600-6600m deep. The temperature of the layer is higher than 132 and the pressure is greater than 62MPa. The reservoir is with a high fluid properties, mainly including thin oil, heavy oil, condensate oil, gas and so on; the ground is very hard to drill, so we can foresee low drilling speed, long drilling period and high drilling cost, which will surely restrict the employing progress of the reservoir.

Properties of Shocked Polymers: Mbar experiments on Z and multi-scale simulations

NASA Astrophysics Data System (ADS)

Mattsson, Thomas R.

2010-03-01

Significant progress has been made over the last few years in understanding properties of matter subject to strong shocks and other extreme conditions. High-accuracy multi-Mbar experiments and first-principles theoretical studies together provide detailed insights into the physics and chemistry of high energy-density matter. While comprehensive advances have been made for pure elements like deuterium, helium, and carbon, progress has been slower for equally important, albeit more challenging, materials like molecular crystals, polymers, and foams. Hydrocarbon based polymer foams are common materials and in particular they are used in designing shock- and inertial confinement fusion experiments. Depending on their initial density, foams shock to relatively higher pressure and temperature compared to shocked dense polymers/plastics. As foams and polymers are shocked, they exhibit both structural and chemical transitions. We will present experimental and theoretical results for shocked polymers in the Mbar regime. By shock impact of magnetically launched flyer plates on poly(4-methyl-1-pentene) foams, we create multi-Mbar pressures in a dense plasma mixture of hydrogen, carbon, at temperatures of several eV. Concurrently with executing experiments, we analyze the system by multi-scale simulations, from density functional theory to continuum magneto-hydrodynamics simulations. In particular, density functional theory (DFT) molecular dynamics (MD) and classical MD simulations of the principal shock Hugoniot will be presented in detail for two hydrocarbon polymers: polyethylene (PE) and poly(4-methyl-1-pentene) (PMP).

Relationship between progression of visual field defect and intraocular pressure in primary open-angle glaucoma.

PubMed

Naito, Tomoko; Yoshikawa, Keiji; Mizoue, Shiro; Nanno, Mami; Kimura, Tairo; Suzumura, Hirotaka; Shiraga, Fumio

2015-01-01

To analyze the relationship between intraocular pressure (IOP) and the progression of visual field defects in Japanese primary open-angle glaucoma (POAG) and normal-tension glaucoma (NTG) patients. The subjects of the study were patients undergoing treatment for POAG or NTG who had performed visual field tests at least ten times with a Humphrey field analyzer (Swedish interactive thresholding algorithm standard, C30-2 program). The progression of visual field defects was defined by a significantly negative value of the mean deviation slope at the final visual field test during the follow-up period. The relationships between the progression of visual field defects and IOP, as well as other clinical factors, were retrospectively analyzed. A total of 156 eyes of 156 patients were included in the analysis. Significant progression of visual field defects was observed in 70 eyes of 70 patients (44.9%), while no significant progression was evident in 86 eyes of 86 patients (55.1%). The eyes with visual field defect progression had significantly lower baseline IOP (P<0.05), as well as significantly lower IOP reduction rate (P<0.01). The standard deviation of IOP values during follow-up was significantly greater in the eyes with visual field defect progression than in eyes without (P<0.05). Reducing IOP is thought to be useful for Japanese POAG or NTG patients to suppress the progression of visual field defects. In NTG, IOP management should take into account not only achieving the target IOP, but also minimizing the fluctuation of IOP during follow-up period.

Human responses to upright tilt: a window on central autonomic integration

NASA Technical Reports Server (NTRS)

Cooke, W. H.; Hoag, J. B.; Crossman, A. A.; Kuusela, T. A.; Tahvanainen, K. U.; Eckberg, D. L.

1999-01-01

1. We examined interactions between haemodynamic and autonomic neural oscillations during passive upright tilt, to gain better insight into human autonomic regulatory mechanisms. 2. We recorded the electrocardiogram, finger photoplethysmographic arterial pressure, respiration and peroneal nerve muscle sympathetic activity in nine healthy young adults. Subjects breathed in time with a metronome at 12 breaths min-1 (0.2 Hz) for 5 min each, in supine, and 20, 40, 60, 70 and 80 deg head-up positions. We performed fast Fourier transform (and autoregressive) power spectral analyses and integrated low-frequency (0.05-0.15 Hz) and respiratory-frequency (0. 15-0.5 Hz) spectral powers. 3. Integrated areas of muscle sympathetic bursts and their low- and respiratory-frequency spectral powers increased directly and significantly with the tilt angle. The centre frequency of low-frequency sympathetic oscillations was constant before and during tilt. Sympathetic bursts occurred more commonly during expiration than inspiration at low tilt angles, but occurred equally in expiration and inspiration at high tilt angles. 4. Systolic and diastolic pressures and their low- and respiratory-frequency spectral powers increased, and R-R intervals and their respiratory-frequency spectral power decreased progressively with the tilt angle. Low-frequency R-R interval spectral power did not change. 5. The cross-spectral phase angle between systolic pressures and R-R intervals remained constant and consistently negative at the low frequency, but shifted progressively from positive to negative at the respiratory frequency during tilt. The arterial baroreflex modulus, calculated from low-frequency cross-spectra, decreased at high tilt angles. 6. Our results document changes of baroreflex responses during upright tilt, which may reflect leftward movement of subjects on their arterial pressure sympathetic and vagal response relations. The intensity, but not the centre frequency of low-frequency cardiovascular rhythms, is modulated by the level of arterial baroreceptor input. Tilt reduces respiratory gating of sympathetic and vagal motoneurone responsiveness to stimulatory inputs for different reasons; during tilt, sympathetic stimulation increases to a level that overwhelms the respiratory gate, and vagal stimulation decreases to a level below that necessary for maximal respiratory gating to occur.

Introduction to the structures and processes of subduction zones

NASA Astrophysics Data System (ADS)

Zheng, Yong-Fei; Zhao, Zi-Fu

2017-09-01

Subduction zones have been the focus of many studies since the advent of plate tectonics in 1960s. Workings within subduction zones beneath volcanic arcs have been of particular interest because they prime the source of arc magmas. The results from magmatic products have been used to decipher the structures and processes of subduction zones. In doing so, many progresses have been made on modern oceanic subduction zones, but less progresses on ancient oceanic subduction zones. On the other hand, continental subduction zones have been studied since findings of coesite in metamorphic rocks of supracrustal origin in 1980s. It turns out that high-pressure to ultrahigh-pressure metamorphic rocks in collisional orogens provide a direct target to investigate the tectonism of subduction zones, whereas oceanic and continental arc volcanic rocks in accretionary orogens provide an indirect target to investigate the geochemistry of subduction zones. Nevertheless, metamorphic dehydration and partial melting at high-pressure to ultrahigh-pressure conditions are tectonically applicable to subduction zone processes at forearc to subarc depths, and crustal metasomatism is the physicochemical mechanism for geochemical transfer from the slab to the mantle in subduction channels. Taken together, these provide us with an excellent opportunity to find how the metamorphic, metasomatic and magmatic products are a function of the structures and processes in both oceanic and continental subduction zones. Because of the change in the thermal structures of subduction zones, different styles of metamorphism, metasomatism and magmatism are produced at convergent plate margins. In addition, juvenile and ancient crustal rocks have often suffered reworking in episodes independent of either accretionary or collisional orogeny, leading to continental rifting metamorphism and thus rifting orogeny for mountain building in intracontinental settings. This brings complexity to distinguish the syn-subduction processes and products from post-subduction processes and products. Nevertheless, available results indicate that our definition and understanding of subduction zone processes and products can be advanced by the convergence of observations and interpretations from geochemical, geological, geophysical and geodynamic studies of both oceanic and continental subduction zones. Therefore, insights into subduction zones can be provided by intergration of different approaches from different targets in the near future.

Introduction to the structures and processes of subduction zones

NASA Astrophysics Data System (ADS)

Zheng, Yong-Fei; Zhao, Zi-Fu

2017-09-01

Subduction zones have been the focus of many studies since the advent of plate tectonics in 1960s. Workings within subduction zones beneath volcanic arcs have been of particular interest because they prime the source of arc magmas. The results from magmatic products have been used to decipher the structures and processes of subduction zones. In doing so, many progresses have been made on modern oceanic subduction zones, but less progresses on ancient oceanic subduction zones. On the other hand, continental subduction zones have been studied since findings of coesite in metamorphic rocks of supracrustal origin in 1980s. It turns out that high-pressure to ultrahigh-pressure metamorphic rocks in collisional orogens provide a direct target to investigate the tectonism of subduction zones, whereas oceanic and continental arc volcanic rocks in accretionary orogens provide an indirect target to investigate the geochemistry of subduction zones. Nevertheless, metamorphic dehydration and partial melting at high-pressure to ultrahigh-pressure conditions are tectonically applicable to subduction zone processes at forearc to subarc depths, and crustal metasomatism is the physicochemical mechanism for geochemical transfer from the slab to the mantle in subduction channels. Taken together, these provide us with an excellent opportunity to find how the metamorphic, metasomatic and magmatic products are a function of the structures and processes in both oceanic and continental subduction zones. Because of the change in the thermal structures of subduction zones, different styles of metamorphism, metasomatism and magmatism are produced at convergent plate margins. In addition, juvenile and ancient crustal rocks have often suffered reworking in episodes independent of either accretionary or collisional orogeny, leading to continental rifting metamorphism and thus rifting orogeny for mountain building in intracontinental settings. This brings complexity to distinguish the syn-subduction processes and products from post-subduction processes and products. Nevertheless, available results indicate that our definition and understanding of subduction zone processes and products can be advanced by the convergence of observations and interpretations from geochemical, geological, geophysical and geodynamic studies of both oceanic and continental subduction zones. Therefore, insights into subduction zones can be provided by integration of different approaches from different targets in the near future.

Human responses to upright tilt: a window on central autonomic integration.

PubMed

Cooke, W H; Hoag, J B; Crossman, A A; Kuusela, T A; Tahvanainen, K U; Eckberg, D L

1999-06-01

1. We examined interactions between haemodynamic and autonomic neural oscillations during passive upright tilt, to gain better insight into human autonomic regulatory mechanisms. 2. We recorded the electrocardiogram, finger photoplethysmographic arterial pressure, respiration and peroneal nerve muscle sympathetic activity in nine healthy young adults. Subjects breathed in time with a metronome at 12 breaths min-1 (0.2 Hz) for 5 min each, in supine, and 20, 40, 60, 70 and 80 deg head-up positions. We performed fast Fourier transform (and autoregressive) power spectral analyses and integrated low-frequency (0.05-0.15 Hz) and respiratory-frequency (0. 15-0.5 Hz) spectral powers. 3. Integrated areas of muscle sympathetic bursts and their low- and respiratory-frequency spectral powers increased directly and significantly with the tilt angle. The centre frequency of low-frequency sympathetic oscillations was constant before and during tilt. Sympathetic bursts occurred more commonly during expiration than inspiration at low tilt angles, but occurred equally in expiration and inspiration at high tilt angles. 4. Systolic and diastolic pressures and their low- and respiratory-frequency spectral powers increased, and R-R intervals and their respiratory-frequency spectral power decreased progressively with the tilt angle. Low-frequency R-R interval spectral power did not change. 5. The cross-spectral phase angle between systolic pressures and R-R intervals remained constant and consistently negative at the low frequency, but shifted progressively from positive to negative at the respiratory frequency during tilt. The arterial baroreflex modulus, calculated from low-frequency cross-spectra, decreased at high tilt angles. 6. Our results document changes of baroreflex responses during upright tilt, which may reflect leftward movement of subjects on their arterial pressure sympathetic and vagal response relations. The intensity, but not the centre frequency of low-frequency cardiovascular rhythms, is modulated by the level of arterial baroreceptor input. Tilt reduces respiratory gating of sympathetic and vagal motoneurone responsiveness to stimulatory inputs for different reasons; during tilt, sympathetic stimulation increases to a level that overwhelms the respiratory gate, and vagal stimulation decreases to a level below that necessary for maximal respiratory gating to occur.

Transcendental Meditation and Progressive Relaxation: Their Physiological Effects.

ERIC Educational Resources Information Center

Throll, D. A.

1982-01-01

Measured oxygen consumption, subjects' respiration rate, heart rate, and blood pressure before and after learned Transcendental Meditation (TM) or Jacobson's Progressive Relaxation. Found TM group displayed more significant decreases during meditation and activity, explained primarily in terms of greater amount of time the TM group spent on their…

Intragenerational Social Mobility and Changes in Blood Pressure: Longitudinal Analysis From the ELSA-Brasil Study.

PubMed

Guimarães, Joanna M N; Griep, Rosane H; Clarke, Philippa J; Fonseca, Maria J M; Barreto, Sandhi M; Giatti, Luana; Lotufo, Paulo A; Mill, Jose G; Pacheco, Antonio G; Chor, Dora

2018-05-07

During the past 4 decades, the highest worldwide blood pressure (BP) levels have shifted from high-income countries to low- and middle-income countries. We investigated the association of intragenerational social mobility with changes in BP and also with the incidence of hypertension over a 4-year follow-up. Data for 6,529 baseline participants from ELSA-Brasil born between 1938 and 1975 were used. Based on a social mobility matrix, occupational social mobility was defined as the change in occupational social class between participants' first occupation and current occupation (stable high; upward; downward; stable low). Incident hypertension was defined as systolic blood pressure (SBP) ≥ 140 mm Hg or diastolic blood pressure (DBP) ≥ 90 mm Hg or use of antihypertensive medication. Hypertensive participants at baseline were excluded. Mixed effects regression models were used. Compared to the stable high group, the downwardly mobile group showed a higher increase over time in both SBP (β = 1.49, 95% CI 0.60; 2.37) and DBP (β = 0.96, 95% CI 0.32; 1.59) after adjustments for background characteristics and also proximal risk factors such as health-related behaviors and body mass index as time-dependent covariates, and diabetes. In contrast, upward mobility had no influence on BP changes (β = 0.67, 95% CI -0.07; 1.41 for SBP, and β = 0.47, 95% CI -0.05; 1.00 for DBP). Social mobility was not associated with the incidence of hypertension. We showed socioeconomic inequalities in BP progression over the life course. The longitudinal changes in BP varied by social mobility groups in the context of low- and middle-income countries, where high BP has become most prevalent.

The diamond anvil cell as a deformation apparatus for investigating the rheology of the deep Earth

NASA Astrophysics Data System (ADS)

Gillet, P.; Merkel, S.; Merkel, S.; Wenk, H.; Shen, G.; Shu, J.; Hemley, R.; Mao, H.

2001-12-01

Considerable progress has been made in establishing deformation mechanisms for minerals and rocks from the Earth's crust and and upper mantle. However, much less is know about the deeper Earth's minerals because the pressures are beyond the conditions reached by ordinary deformation apparatus such as the Griggs, Heard or Paterson apparatus. Diamond anvil cells allow investigations of the whole pressure and temperature range of the lower mantle. In pilot experiments on hcp-Fe at 54 and 220 GPa development of a strong textures was observed and slip systems of the hexagonal closed packed iron could be identified (Wenk et al., 2000). The technique has now been further refined in order to study in situ the shear strength and deformation mechanisms at high pressure in great details. In this study, we apply this technique to pure periclase (MgO) to pressures of 47 GPa. The uniaxial stress component in the pollycrystalline MgO sample is found to increase rapidly to 8.5 GPa at a pressure of 10 GPa in all experiments. According to our measurements, the preferred orientation is due to deformation by slip. A quantitative comparison between the experimental textures and results from polycrystalline plasticity suggest that the {110}<110> is the only significantly active slip system under very high confining pressure. These data demonstrate the feasability of determining deformation mechanisms and shear strength under pressures relevant for the Earth's lower mantle. This approach can now be extended to study variations of the properties with both pressure and temperature and can also be used to study other deep Earth's materials such as magnesiowustite and perovskite. Wenk, H.R., S. Matthies, R.J. Hemley, H.K. Mao, and J. Shu, Nature, 405, 1044-1047, 2000. Merkel, S., H.R. Wenk, J. Shu, G. Shen, Ph. Gillet, H.K. Mao, and R.J. Hemley, J. Geophys. Res. submitted

Chronic baroreflex activation restores spontaneous baroreflex control and variability of heart rate in obesity-induced hypertension

PubMed Central

Iliescu, Radu; Tudorancea, Ionut; Irwin, Eric D.

2013-01-01

The sensitivity of baroreflex control of heart rate is depressed in subjects with obesity hypertension, which increases the risk for cardiac arrhythmias. The mechanisms are not fully known, and there are no therapies to improve this dysfunction. To determine the cardiovascular dynamic effects of progressive increases in body weight leading to obesity and hypertension in dogs fed a high-fat diet, 24-h continuous recordings of spontaneous fluctuations in blood pressure and heart rate were analyzed in the time and frequency domains. Furthermore, we investigated whether autonomic mechanisms stimulated by chronic baroreflex activation and renal denervation—current therapies in patients with resistant hypertension, who are commonly obese—restore cardiovascular dynamic control. Increases in body weight to ∼150% of control led to a gradual increase in mean arterial pressure to 17 ± 3 mmHg above control (100 ± 2 mmHg) after 4 wk on the high-fat diet. In contrast to the gradual increase in arterial pressure, tachycardia, attenuated chronotropic baroreflex responses, and reduced heart rate variability were manifest within 1–4 days on high-fat intake, reaching 130 ± 4 beats per minute (bpm) (control = 86 ± 3 bpm) and ∼45% and <20%, respectively, of control levels. Subsequently, both baroreflex activation and renal denervation abolished the hypertension. However, only baroreflex activation effectively attenuated the tachycardia and restored cardiac baroreflex sensitivity and heart rate variability. These findings suggest that baroreflex activation therapy may reduce the risk factors for cardiac arrhythmias as well as lower arterial pressure. PMID:23913707

High-pressure alchemy on a small-pore zeolite

NASA Astrophysics Data System (ADS)

Lee, Y.

2011-12-01

While an ever-expanding variety of zeolites with a wide range of framework topology is available, it is desirable to have a way to tailor the chemistry of the zeolitic nanopores for a given framework topology via controlling both the coordination-inclusion chemistry and framework distortion/relaxation. This is, however, subjected to the ability of a zeolitic nanopore to allow the redistribution of cations-water assembly and/or insertion of foreign molecules into the pores and channels. Small-pore zeolites such as natrolite (Na16Al16Si24O80x16H2O), however, have been known to show very limited capacity for any changes in the confinement chemistry. We have recently shown that various cation-exchanged natrolites can be prepared under modest conditions from natural sodium natrolite and exhibit cation-dependent volume expansions by up to 18.5% via converting the elliptical channels into progressively circular ones. Here, we show that pressure can be used as a unique and clean tool to further manipulate the chemistry of the natrolite nanopores. Our recent crystallographic and spectroscopic studies of pressure-insertion of foreign molecules, trivalent-cation exchange under pressure, and pressure-induced inversion of cation-water coordination and pore geometry in various cation-exchanged natrolites will be presented.

Compressed-air work is entering the field of high pressures.

PubMed

Le Péchon, J Cl; Gourdon, G

2010-01-01

Since 1850, compressed-air work has been used to prevent shafts or tunnels under construction from flooding. Until the 1980s, workers were digging in compressed-air environments. Since the introduction of tunnel boring machines (TBMs), very little digging under pressure is needed. However, the wearing out of cutter-head tools requires inspection and repair. Compressed-air workers enter the pressurized working chamber only occasionally to perform such repairs. Pressures between 3.5 and 4.5 bar, that stand outside a reasonable range for air breathing, were reached by 2002. Offshore deep diving technology had to be adapted to TBM work. Several sites have used mixed gases: in Japan for deep shaft sinking (4.8 bar), in The Netherlands at Western Scheldt Tunnels (6.9 bar), in Russia for St. Petersburg Metro (5.8 bar) and in the United States at Seattle (5.8 bar). Several tunnel projects are in progress that may involve higher pressures: Hallandsås (Sweden) interventions in heliox saturation up to 13 bar, and Lake Mead (U.S.) interventions to about 12 bar (2010). Research on TBMs and grouting technologies tries to reduce the requirements for hyperbaric works. Adapted international rules, expertise and services for saturation work, shuttles and trained personnel matching industrial requirements are the challenges.

Recent advances in collisional effects on spectra of molecular gases and their practical consequences

NASA Astrophysics Data System (ADS)

Hartmann, Jean-Michel; Tran, Ha; Armante, Raymond; Boulet, Christian; Campargue, Alain; Forget, François; Gianfrani, Livio; Gordon, Iouli; Guerlet, Sandrine; Gustafsson, Magnus; Hodges, Joseph T.; Kassi, Samir; Lisak, Daniel; Thibault, Franck; Toon, Geoffrey C.

2018-07-01

We review progress, since publication of the book ``Collisional effects on molecular spectra: Laboratory experiments and models, consequences for applications" (Elsevier, Amsterdam, 2008), on measuring, modeling and predicting the influence of pressure (ie of intermolecular collisions) on the spectra of gas molecules. We first introduce recently developed experimental techniques of high accuracy and sensitivity. We then complement the aforementioned book by presenting the theoretical approaches, results and data proposed (mostly) in the last decade on the topics of isolated line shapes, line-broadening and -shifting, line-mixing, the far wings and associated continua, and collision-induced absorption. Examples of recently demonstrated consequences of the progress in the description of spectral shapes for some practical applications (metrology, probing of gas media, climate predictions) are then given. Remaining issues and directions for future research are finally discussed.

Zebrafish as a model to assess cancer heterogeneity, progression and relapse

PubMed Central

Blackburn, Jessica S.; Langenau, David M.

2014-01-01

Clonal evolution is the process by which genetic and epigenetic diversity is created within malignant tumor cells. This process culminates in a heterogeneous tumor, consisting of multiple subpopulations of cancer cells that often do not contain the same underlying mutations. Continuous selective pressure permits outgrowth of clones that harbor lesions that are capable of enhancing disease progression, including those that contribute to therapy resistance, metastasis and relapse. Clonal evolution and the resulting intratumoral heterogeneity pose a substantial challenge to biomarker identification, personalized cancer therapies and the discovery of underlying driver mutations in cancer. The purpose of this Review is to highlight the unique strengths of zebrafish cancer models in assessing the roles that intratumoral heterogeneity and clonal evolution play in cancer, including transgenesis, imaging technologies, high-throughput cell transplantation approaches and in vivo single-cell functional assays. PMID:24973745

Research on Rapid Initial Adaption to the Environment of a Plateau.

PubMed

Wang, Bin Hua; Cao, Zheng Tao; Wu, Feng; Yang, Jun; Liu, Yuan Yuan; Yu, Meng Sun

2016-09-01

We designed two types of pre-adaption plans for this study. One was a pre-adaption training with progressive intermittent hypoxia, with a constant lower pressure oxygen tank used in the plain before arriving at the plateau (PG). The other was by progressively increasing the time of exposure to hypoxia with oxygen supplied in stages after radical plateau (RG). By testing the blood oxygen saturation (SpO2), heart rate (HR), and quality of sleep after arriving at the 3800 m high plateau, results showed that the pre-acclimatization and radical groups performed better than the control group (CG). Both strategies were equivalent in terms of effects and principles in providing more flexible choices for acclimatization. Copyright © 2016 The Editorial Board of Biomedical and Environmental Sciences. Published by China CDC. All rights reserved.

K 3 Fe(CN) 6 under External Pressure: Dimerization of CN – Coupled with Electron Transfer to Fe(III)

DOE PAGES

Li, Kuo; Zheng, Haiyan; Wang, Lijuan; ...

2015-09-14

The addition polymerization of charged monomers like C≡C 2– and C≡N– is scarcely seen at ambient conditions but can progress under external pressure with their conductivity significantly enhanced, which expands the research field of polymer science to inorganic salts. Moreover, the reaction pressures of transition metal cyanides like Prussian blue and K 3Fe(CN) 6 are much lower than that of alkali cyanides. To figure out the effect of the transition metal on the reaction, the crystal structure and electronic structure of K 3Fe(CN) 6 under external pressure are investigated by in situ neutron diffraction, in situ X-ray absorption fine structuremore » (XAFS), and neutron pair distribution functions (PDF) up to ~15 GPa. The cyanide anions react following a sequence of approaching–bonding–stabilizing. The Fe(III) brings the cyanides closer which makes the bonding progress at a low pressure (2–4 GPa). At ~8 GPa, an electron transfers from the CN to Fe(III), reduces the charge density on cyanide ions, and stabilizes the reaction product of cyanide. Finally, from this study we can conclude that bringing the monomers closer and reducing their charge density are two effective routes to decrease the reaction pressure, which is important for designing novel pressure induced conductor and excellent electrode materials.« less

Optical and electronic properties of 2 H -Mo S2 under pressure: Revealing the spin-polarized nature of bulk electronic bands

NASA Astrophysics Data System (ADS)

Brotons-Gisbert, Mauro; Segura, Alfredo; Robles, Roberto; Canadell, Enric; Ordejón, Pablo; Sánchez-Royo, Juan F.

2018-05-01

Monolayers of transition-metal dichalcogenide semiconductors present spin-valley locked electronic bands, a property with applications in valleytronics and spintronics that is usually believed to be absent in their centrosymmetric (as the bilayer or bulk) counterparts. Here we show that bulk 2 H -Mo S2 hides a spin-polarized nature of states determining its direct band gap, with the spin sequence of valence and conduction bands expected for its single layer. This relevant finding is attained by investigating the behavior of the binding energy of A and B excitons under high pressure, by means of absorption measurements and density-functional-theory calculations. These results raise an unusual situation in which bright and dark exciton degeneracy is naturally broken in a centrosymmetric material. Additionally, the phonon-assisted scattering process of excitons has been studied by analyzing the pressure dependence of the linewidth of discrete excitons observed at the absorption coefficient edge of 2 H -Mo S2 . Also, the pressure dependence of the indirect optical transitions of bulk 2 H -Mo S2 has been analyzed by absorption measurements and density-functional-theory calculations. These results reflect a progressive closure of the indirect band gap as pressure increases, indicating that metallization of bulk Mo S2 may occur at pressures higher than 26 GPa.

Elastic Nonlinear Response in Granular Media Under Resonance Conditions

NASA Astrophysics Data System (ADS)

Jia, X.; Johnson, P. A.

2004-12-01

We are studying the elastic linear and nonlinear behavior of granular media using dynamic wave methods. In the work presented here, our goal is to quantify the elastic nonlinear response by applying wave resonance. Resonance studies are desirable because they provide the means to easily study amplitude dependencies of elastic nonlinear behavior and thus to characterize the physical nature of the elastic nonlinearity. This work has implications for a variety of topics, in particular, the in situ nonlinear response of surface sediments. For this work we constructed an experimental cell in which high sensitivity dynamic resonance studies were conducted using granular media under controlled effective pressure. We limit our studies here to bulk modes but have the capability to employ shear waves as well. The granular media are composed of glass beads held under pressure by a piston, while applying resonance waves from transducers as both the excitation and the material probe. The container is closed with two fitted pistons and a normal load is applied to the granular sample across the top piston. Force and displacement are measured directly. Resonant frequency sweeps with frequencies corresponding to the fundamental bulk mode are applied to the longitudinal source transducer. The pore pressure in the system is 1 atm. The glass beads used in our experiments are of diameter 0.5 mm, randomly deposited in a duralumin cylinder of diameter 30 mm and height of 15 mm. This corresponds to a granular skeleton acoustic wave velocity of v ª 750m/s under 50 N of force [0.07 Mpa]. The loaded system gives fundamental mode resonances in the audio frequency band at half a wavelength where resonance frequency is effective-pressure dependent. The volume fraction of glass beads thus obtained is found to be 0.63 ± 0.01. Plane-wave generating and detecting transducers of diameter 30 mm are placed on axis at the top and bottom of the cylindrical container in direct contact with the glass beads. The wave signals are detected using a lock-in amplifier, and frequency and amplitude are recorded on computer. Drive frequency is swept from below to above the resonance mode. A typical frequency sweep is 3 kHz in width with a frequency sampling of 6 Hz. Frequency sweeps are applied at progressively increasing drive voltages to test for nonlinear-dynamical induced modulus softening. The resonance frequency at peak amplitude corresponds directly to modulus. We find significant elastic nonlinearity at all effective pressures, manifest by the fundamental-mode resonance curves decreasing progressively, at progressively increasing drive level. This is equivalent to progressive material softening with wave amplitude, meaning the wavespeed and modulus diminish. The wave dissipation simultaneously increases (Johnson and Sutin 2004). For example, at 0.11 Mpa effective pressure the observed change in resonance frequency of about 2.6% corresponds to a material bulk modulus decrease of about 5.2%. Strain amplitudes are 10-7-10-6. Thus, we would predict that surface sediments should have significant elastic nonlinear response beginning at about 10-6 strain amplitude. reference: Johnson, P. and A. Sutin, Slow dynamics in diverse solids, J. Acoust. Soc Am., in press (2004).

High-Pressure Quasi-Isentropic Loading and Unloading of Interferometer Windows on the Veloce Pulsed Power Generator

NASA Astrophysics Data System (ADS)

Ao, Tommy; Asay, James; Knudson, Marcus; Davis, Jean-Paul

2007-06-01

The Isentropic Compression Experiment technique has proven to be a valuable complement to the well-established method of shock compression of condensed matter. However, whereas the high-pressure compression response of window materials has been studied extensively under shock loading, similar knowledge of these materials under ICE loading is limited. We present recent experimental results on the isentropic compression of the high-pressure windows sapphire and LiF. It has previously been observed that c-cut sapphire yields under shock loading at the HEL of ˜15-18GPa, and subsequently loses transparency at higher stresses. However, it will be shown that under isentropic ramp wave loading sapphire appears to remain elastic and transparent at stresses well above 20GPa [D.B. Hayes et al, JAP 94, 2331 (2003)]. LiF is another frequently used window material in isentropic loading and unloading experiments, yet the unloading response of LiF is usually neglected. Research is in progress to measure strength properties of LiF for ramp loading and unloading. It will be shown how the strength of LiF may influence wave profile analysis and thus inferred material strength. Sandia is a multiprogram laboratory operated by Sandia Corp., a Lockheed Martin Company, for the US DOE's NNSA under Contract No.DE-AC04-94AL85000.

Reduced baroreflex sensitivity with volume loading in conscious dogs

NASA Technical Reports Server (NTRS)

Vatner, S. F.; Boettcher, D. H.; Heyndrickx, G. R.; Mcritchie, R. J.

1975-01-01

Results of studies of the Bainbridge reflex in intact conscious dogs are presented. They indicate that arterial baroreflex sensitivity is reduced progressively as atrial pressure is raised by volume loading; this observation explains how heart rate can rise markedly in the presence of an elevated arterial blood pressure.

60. (Credit LSU) Hyatt pressure filters (originally installed c1890) in ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

60. (Credit LSU) Hyatt pressure filters (originally installed c1890) in filter wing of McNeil Station in 1904. (From: Shreveport Progressive League, Shreveport of To-Day, September 1904, p. 47) - McNeil Street Pumping Station, McNeil Street & Cross Bayou, Shreveport, Caddo Parish, LA

Anger Expression and Blood Pressure in Adolescents

ERIC Educational Resources Information Center

Starner, Tamie M.; Peters, Rosalind M.

2004-01-01

The clinical significance of childhood hypertension is important as elevated pressures during childhood are found to follow a progressively increasing track into adulthood. Little work has been done to examine the relationship of emotions and emotional behavioral factors to the development of hypertension in children. Using the Roy Adaptation…

High-pressure coolant effect on the surface integrity of machining titanium alloy Ti-6Al-4V: a review

NASA Astrophysics Data System (ADS)

Liu, Wentao; Liu, Zhanqiang

2018-03-01

Machinability improvement of titanium alloy Ti-6Al-4V is a challenging work in academic and industrial applications owing to its low thermal conductivity, low elasticity modulus and high chemical affinity at high temperatures. Surface integrity of titanium alloys Ti-6Al-4V is prominent in estimating the quality of machined components. The surface topography (surface defects and surface roughness) and the residual stress induced by machining Ti-6Al-4V occupy pivotal roles for the sustainability of Ti-6Al-4V components. High-pressure coolant (HPC) is a potential choice in meeting the requirements for the manufacture and application of Ti-6Al-4V. This paper reviews the progress towards the improvements of Ti-6Al4V surface integrity under HPC. Various researches of surface integrity characteristics have been reported. In particularly, surface roughness, surface defects, residual stress as well as work hardening are investigated in order to evaluate the machined surface qualities. Several coolant parameters (including coolant type, coolant pressure and the injection position) deserve investigating to provide the guidance for a satisfied machined surface. The review also provides a clear roadmap for applications of HPC in machining Ti-6Al4V. Experimental studies and analysis are reviewed to better understand the surface integrity under HPC machining process. A distinct discussion has been presented regarding the limitations and highlights of the prospective for machining Ti-6Al4V under HPC.

Management of Hypertension in Patients with Chronic Kidney Disease in Asia.

PubMed

Huang, Qi-Fang; Hoshide, Satoshi; Cheng, Hao-Min; Park, Sungha; Park, Chang-Gyu; Chen, Chen-Huan; Kario, Kazuomi; Wang, Ji-Guang

2016-01-01

Hypertension is both a cause and consequence of chronic kidney disease (CKD). According to the Chinese national survey in 2007-2010, the prevalence of CKD was much higher in hypertensive patients (18.9%, n=16,691) than in the overall population sample (10.8%, n=47,204). CKD in hypertension confers risks to the kidneys as well as other organs. Probably because of high dietary salt intake, Asian hypertensive patients with CKD show high prevalence of non-dipping and reversed dipping blood pressure pattern, and may have even higher risks of cardiovascular disease. Therefore, out-of-office blood pressure evaluation and comprehensive cardiovascular evaluations are required. Most of current hypertension guidelines recommend intensive antihypertensive treatment in hypertensive patients with CKD. This is probably of particular relevance for cardiovascular prevention in Asia, because stroke, as a major complication of hypertension in Asia, is more closely related to blood pressure than coronary events. Intensive blood pressure control to 130/80 mmHg is often required to prevent CKD progression and cardiovascular complications. The inhibitors of the renin-angiotensin system (RAS) are recommended as the first line antihypertensive medications in patients with a glomerular filtration rate higher than 30 ml/min/1.73 m², which may more efficaciously prevent end-stage renal disease and cardiovascular events. Nonetheless, combination therapy of RAS inhibitors with other classes of antihypertensive drugs, such as calcium-channel blockers, diuretics, etc, is required to control blood pressure to the target. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

[Indicators of general, cerebral, and regional hemodynamics in myopic schoolchildren aged 13-15 years].

PubMed

Iastrebtseva, T A; Chuprov, A D; Plotnikova, Iu A

2002-01-01

110 schoolchildren aged 13-15 years were examined. 24 of them had pseudomyopia and 6 patients myopia of various forms. A control group consisted of 38 children. Central hemodynamics was estimated by average dynamic pressure, cerebral hemodynamics--by rheoencephalography, regional hemodynamics--by dopplerography of the internal carotid and suprapubic arteries. It was found that with myopia progression, the average dynamic pressure positively comes down with reduction of reographic waves amplitude in rheogram. The blood flow rate in internal carotid and suprapubic arteries has no substantial impact on myopia course. Predisposition to arterial hypotension is a risk factor for myopia development and progression.

Pressure effect on dissimilatory sulfate reduction

NASA Astrophysics Data System (ADS)

Williamson, A. J.; Carlson, H. K.; Coates, J. D.

2015-12-01

Biosouring is the production of H2S by sulfate reducing microorganisms (SRM) in-situ or in the produced fluids of oil reservoirs. Sulfide is explosive, toxic and corrosive which can trigger equipment and transportation failure, leading to environmental catastrophe. As oil exploration and reservoir development continue, subsequent enhanced recovery is occurring in progressively deeper formations and typical oil reservoir pressures range from 10-50 MPa. Therefore, an understanding of souring control effects will require an accurate understanding of the influence of pressure on SRM metabolism and the efficacy of souring control treatments at high pressure. Considerable work to date has focussed on souring control at ambient pressure; however, the influence of pressure on biogeochemical processes and souring treatments in oil reservoirs is poorly understood. To explore the impact of pressure on SRM, wild type Desulfovibrio alaskensis G20 (isolated from a producing oil well in Ventura County, California) was grown under a range of pressures (0.1-14 MPa) at 30 °C. Complete sulfate reduction occurred in all pressures tested within 3 days, but microbial growth was inhibited with increasing pressure. Bar-seq identified several genes associated with flagella biosynthesis (including FlhB) and assembly as important for survival at elevated pressure and fitness was confirmed using individual transposon mutants. Flagellar genes have previously been implicated with biofilm formation and confocal microscopy on glass slides incubated with wild type D. alaskensis G20 showed more biomass associated with surfaces under pressure, highlighting the link between pressure, flagellar and biofilm formation. To determine the effect of pressure on the efficacy of SRM inhibitors, IC50 experiments were conducted and D. alaskensis G20 showed a greater resistance to nitrate and the antibiotic chloramphenicol, but a lower resistance to perchlorate. These results will be discussed in the context of deep subsurface microbiology and oil reservoir biosouring. Overall, this work furthers our understanding of oil reservoir biogeochemistry and highlights the impact of pressure on biofilm formation and biosouring strategies.

The mechanobiology of articular cartilage development and degeneration.

PubMed

Carter, Dennis R; Beaupré, Gary S; Wong, Marcy; Smith, R Lane; Andriacchi, Tom P; Schurman, David J

2004-10-01

The development, maintenance, and destruction of cartilage are regulated by mechanical factors throughout life. Mechanical cues in the cartilage fetal endoskeleton influence the expression of genes that guide the processes of growth, vascular invasion, and ossification. Intermittent fluid pressure maintains the cartilage phenotype whereas mild tension (or shear) promotes growth and ossification. The articular cartilage thickness is determined by the position at which the subchondral growth front stabilizes. In mature joints, cartilage is thickest and healthiest where the contact pressure and cartilage fluid pressure are greatest. The depth-dependent histomorphology reflects the local fluid pressure, tensile strain, and fluid exudation. Osteoarthritis represents the final demise and loss of cartilage in the skeletal elements. The initiation and progression of osteoarthritis can follow many pathways and can be promoted by mechanical factors including: (1) reduced loading, which activates the subchondral growth front by reducing fluid pressure; (2) blunt impact, causing microdamage and activation of the subchondral growth front by local shear stress; (3) mechanical abnormalities that increase wear at the articulating surface; and (4) other mechanically related factors. Research should be directed at integrating our mechanical understanding of osteoarthritis pathogenesis and progression within the framework of cellular and molecular events throughout ontogeny.

Transient Flows in a Pipe System with Pump Shut-Down and the Simultaneous Closing of a Spherical Valve

NASA Astrophysics Data System (ADS)

Zhang, Zh.

2016-11-01

Because of the limited value of the wave propagation speed in water the propagation of a pressure surge in transient flows can be tracked in the time series. This enables both the pressure head and the flow velocity in pipe flows to be determined as a function of both the coordinate along the pipe and the time. The propagation of the pressure surge includes both wave transmission and reflection. The latter occurs where the flow section is changed. The wave tracking method has been demonstrated as highly accurate and subsequently was applied to much more complex hydraulic systems, in which the pump is shut off and the spherical valve is simultaneously progressively closed. A combined four-quadrant characteristic of the pump and a spherical valve has been worked out, with which the computational procedure for the transient flow in the complex system could be significantly simplified. It has been demonstrated that not only the pressure surge in the hydraulic system but also the rotational speed of the pump could be satisfactorily computed. The computational algorithm has been demonstrated as quite simple, so that all calculations could be performed simply by means of the Microsoft Excel module.

Telmisartan is more effective than losartan in reducing proteinuria in patients with diabetic nephropathy.

PubMed

Bakris, George; Burgess, Ellen; Weir, Matthew; Davidai, Giora; Koval, Stephen

2008-08-01

In patients with diabetic nephropathy, lowering blood pressure and reducing proteinuria by over 30% correlates with a slower progression to kidney failure. We compared two different angiotensin receptor-blockers in a double blind, prospective trial of 860 patients with type 2 diabetes whose blood pressure levels was over 130/80 mmHg or who were receiving antihypertensive medication(s) and who had a morning spot urinary protein to creatinine ratio of 700 or more. Patients were randomized to telmisartan (a highly lipophilic agent with a long half-life) or losartan (with low lipophilicity and short half-life). The primary endpoint was the difference in the urinary albumin to creatinine ratio between the groups at 52 weeks. The geometric coefficient of variation and the mean of the urinary albumin to creatinine ratio fell in both groups at 52 weeks but both were significantly greater for the telmisartan compared to the losartan cohort. Mean systolic blood pressure reductions were not significantly different between groups at trial end. We conclude that telmisartan is superior to losartan in reducing proteinuria in hypertensive patients with diabetic nephropathy, despite a similar reduction in blood pressure.

Shock wave absorber having a deformable liner

DOEpatents

Youngdahl, C.K.; Wiedermann, A.H.; Shin, Y.W.; Kot, C.A.; Ockert, C.E.

1983-08-26

This invention discloses a shock wave absorber for a piping system carrying liquid. The absorber has a plastically deformable liner defining the normal flow boundary for an axial segment of the piping system, and a nondeformable housing is spaced outwardly from the liner so as to define a gas-tight space therebetween. The flow capacity of the liner generally corresponds to the flow capacity of the piping system line, but the liner has a noncircular cross section and extends axially of the piping system line a distance between one and twenty times the diameter thereof. Gas pressurizes the gas-tight space equal to the normal liquid pressure in the piping system. The liner has sufficient structural capacity to withstand between one and one-half and two times this normal liquid pressures; but at greater pressures it begins to plastically deform initially with respect to shape to a more circular cross section, and then with respect to material extension by circumferentially stretching the wall of the liner. A high energy shock wave passing through the liner thus plastically deforms the liner radially into the gas space and progressively also as needed in the axial direction of the shock wave to minimize transmission of the shock wave beyond the absorber.

Low-pressure pulsed focused ultrasound with microbubbles promotes an anticancer immunological response.

PubMed

Liu, Hao-Li; Hsieh, Han-Yi; Lu, Li-An; Kang, Chiao-Wen; Wu, Ming-Fang; Lin, Chun-Yen

2012-11-11

High-intensity focused-ultrasound (HIFU) has been successfully employed for thermal ablation of tumors in clinical settings. Continuous- or pulsed-mode HIFU may also induce a host antitumor immune response, mainly through expansion of antigen-presenting cells in response to increased cellular debris and through increased macrophage activation/infiltration. Here we demonstrated that another form of focused ultrasound delivery, using low-pressure, pulsed-mode exposure in the presence of microbubbles (MBs), may also trigger an antitumor immunological response and inhibit tumor growth. A total of 280 tumor-bearing animals were subjected to sonographically-guided FUS. Implanted tumors were exposed to low-pressure FUS (0.6 to 1.4 MPa) with MBs to increase the permeability of tumor microvasculature. Tumor progression was suppressed by both 0.6 and 1.4-MPa MB-enhanced FUS exposures. We observed a transient increase in infiltration of non-T regulatory (non-Treg) tumor infiltrating lymphocytes (TILs) and continual infiltration of CD8+ cytotoxic T-lymphocytes (CTL). The ratio of CD8+/Treg increased significantly and tumor growth was inhibited. Our findings suggest that low-pressure FUS exposure with MBs may constitute a useful tool for triggering an anticancer immune response, for potential cancer immunotherapy.

Influence of Particle Morphology on 3D Kinematic Behavior and Strain Localization of Sheared Sand

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

Alshibli, Khalid A.; Jarrar, Maha F.; Druckrey, Andrew M.

The constitutive behavior of sheared sand is highly influenced by particle morphology, gradation, mineralogy, specimen density, loading condition, stress path, and boundary conditions. The current literature lacks a three-dimensional (3D) systematic experimental study that investigates the influence of particle morphology, confining pressure, and specimen density on the failure mode of sheared sand. In this paper, surface texture, roundness, and sphericity of three uniform sands and glass beads with similar grain size were quantified by using 3D images of particles. In situ nondestructive 3D synchrotron microcomputed tomography (SMT) was used to monitor the deformation of medium-dense and very dense dry sandmore » specimens that were tested under axisymmetric triaxial loading condition at 15 and 400 kPa confining pressures. The particles were identified and tracked in 3D as shearing progressed within the specimens, and maps of incremental particle translation and rotation were developed and used to uncover the relationship between particle morphology, specimen density, and confining pressure on the deformation and failure mode of sheared sand. This paper discusses the relationship between the failure mode and particle morphology, specimen density, and confining pressure.« less

Progressive Fracture of [0/90/ + or - Theta]s Composite Structure Under Uniform Pressure Load

NASA Technical Reports Server (NTRS)

Gotsis, Pascalis K.; Chamis, Christos C.; Gotsis, Christos K.; Mouratidis, Ericos

2007-01-01

S-Glass/epoxy [0/90/plus or minus theta]s for theta =45 deg., 60 deg., and 75 deg. laminated fiber-reinforced composite stiffened plate was simulated to investigated for damage and fracture progression under uniform pressure. An integrated computer code was augmented for the simulation of the damage initiation, growth, accumulation, and propagation to fracture and to structural collapse. Results show in detail the damage progression sequence and structural fracture resistance during different degradation stages. Damage through the thickness of the laminate initiated first at [0/90/plus or minus 45]s at 15.168 MPa (2200 psi), followed by [0/90/plus or minus 60]s at 16.96 MPa (2460 psi) and finally by [0/90/plus or minus 75]s at 19.3 MPa (2800 psi). After damage initiation happened the cracks propagate rapidly to structural fracture.

Influence of Packing on Low Energy Vibrations of Densified Glasses

NASA Astrophysics Data System (ADS)

Carini, Giovanni, Jr.; Carini, Giuseppe; D'Angelo, Giovanna; Tripodo, Gaspare; Di Marco, Gaetano; Vasi, Cirino; Gilioli, Edmondo

2013-12-01

A comparative study of Raman scattering and low temperature specific heat capacity has been performed on samples of B2O3, which have been high-pressure quenched to go through different glassy phases having growing density to the crystalline state. It has revealed that the excess volume characterizing the glassy networks favors the formation of specific glassy structural units, the boroxol rings, which produce the boson peak, a broad band of low energy vibrational states. The decrease of boroxol rings with increasing pressure of synthesis is associated with the progressive depression of the excess low energy vibrations until their full disappearance in the crystalline phase, where the rings are missing. These observations prove that the additional soft vibrations in glasses arise from specific units whose formation is made possible by the poor atomic packing of the network.

Advances in the design of common pressure vessel nickel hydrogen batteries for aerospace applications

NASA Technical Reports Server (NTRS)

Zagrodnik, Jeffrey P.; Jones, Kenneth R.

1991-01-01

Over 7000 low-earth-orbit (LEO) cycles were demonstrated on a full-size aerospace common pressure vessel (CPV) prototype. The battery demonstrated the capability of the basic CPV design to meet the life and reliability requirements of aerospace missions. Subsequent design modifications have been employed to address the shortcomings of the original design and several new prototypes have been fabricated. These include a 12-cell 125 amp-hour geosynchronous earth-orbit (GEO) battery and a 22-cell 10.5 amp-hour LEO battery. Cells for an 80-cell battery intended to demonstrate the high voltage capability of the CPV design have also been fabricated. In addition, assembly of a 20-cell aircraft starting battery prototype is in progress, and testing of a group of 12-volt, 160 amp-hour terrestrial batteries is continuing.

Accelerating gradient improvement using shape-tailor laser front in radiation pressure acceleration progress

NASA Astrophysics Data System (ADS)

Wang, W. P.; Shen, B. F.; Xu, Z. Z.

2017-05-01

The accelerating gradient of a proton beam is crucial for stable radiation pressure acceleration (RPA) because the multi-dimensional instabilities increase γ times slower in the relativistic region. In this paper, a shape-tailored laser is proposed to significantly accelerate the ions in a controllable high accelerating gradient. In this method, the fastest ions initially rest in the middle of the foil are controlled to catch the compressed electron layer at the end of the hole-boring stage, thus the light-sail stage can start as soon as possible. Then the compressed electron layer is accelerated tightly together with the fastest ions by the shaped laser intensity, which further increases the accelerating gradient in the light-sail stage. Such tailored pulse may be beneficial for the RPA driven by the 10-fs 10 petawatt laser in the future.

Simultaneous Risk Factor Control Using Telehealth to slOw Progression of Diabetic Kidney Disease (STOP-DKD) study: Protocol and baseline characteristics of a randomized controlled trial.

PubMed

Diamantidis, Clarissa J; Bosworth, Hayden B; Oakes, Megan M; Davenport, Clemontina A; Pendergast, Jane F; Patel, Sejal; Moaddeb, Jivan; Barnhart, Huiman X; Merrill, Peter D; Baloch, Khaula; Crowley, Matthew J; Patel, Uptal D

2018-06-01

Diabetic kidney disease (DKD) is the leading cause of end-stage kidney disease (ESKD) in the United States. Multiple risk factors contribute to DKD development, yet few interventions target more than a single DKD risk factor at a time. This manuscript describes the study protocol, recruitment, and baseline participant characteristics for the Simultaneous Risk Factor Control Using Telehealth to slOw Progression of Diabetic Kidney Disease (STOP-DKD) study. The STOP-DKD study is a randomized controlled trial designed to evaluate the effectiveness of a multifactorial behavioral and medication management intervention to mitigate kidney function decline at 3 years compared to usual care. The intervention consists of up to 36 monthly educational modules delivered via telephone by a study pharmacist, home blood pressure monitoring, and medication management recommendations delivered electronically to primary care physicians. Patients seen at seven primary care clinics in North Carolina, with diabetes and [1] uncontrolled hypertension and [2] evidence of kidney dysfunction (albuminuria or reduced estimated glomerular filtration rate [eGFR]) were eligible to participate. Study recruitment completed in December 2014. Of the 281 participants randomized, mean age at baseline was 61.9; 52% were male, 56% were Black, and most were high school graduates (89%). Baseline co-morbidity was high- mean blood pressure was 134/76 mmHg, mean body mass index was 35.7 kg/m 2 , mean eGFR was 80.7 ml/min/1.73 m 2 , and mean glycated hemoglobin was 8.0%. Experiences of recruiting and implementing a comprehensive DKD program to individuals at high risk seen in the primary care setting are provided. NCT01829256. Copyright © 2018 Elsevier Inc. All rights reserved.

Impaired dynamic cerebral autoregulation at extreme high altitude even after acclimatization

PubMed Central

Iwasaki, Ken-ichi; Zhang, Rong; Zuckerman, Julie H; Ogawa, Yojiro; Hansen, Lærke H; Levine, Benjamin David

2011-01-01

Cerebral blood flow (CBF) increases and dynamic cerebral autoregulation is impaired by acute hypoxia. We hypothesized that progressive hypocapnia with restoration of arterial oxygen content after altitude acclimatization would normalize CBF and dynamic cerebral autoregulation. To test this hypothesis, dynamic cerebral autoregulation was examined by spectral and transfer function analyses between arterial pressure and CBF velocity variabilities in 11 healthy members of the Danish High-Altitude Research Expedition during normoxia and acute hypoxia (10.5% O2) at sea level, and after acclimatization (for over 1 month at 5,260 m at Chacaltaya, Bolivia). Arterial pressure and CBF velocity in the middle cerebral artery (transcranial Doppler), were recorded on a beat-by-beat basis. Steady-state CBF velocity increased during acute hypoxia, but normalized after acclimatization with partial restoration of SaO2 (acute, 78%±2% chronic, 89%±1%) and progression of hypocapnia (end-tidal carbon dioxide: acute, 34±2 mm Hg; chronic, 21±1 mm Hg). Coherence (0.40±0.05 Units at normoxia) and transfer function gain (0.77±0.13 cm/s per mm Hg at normoxia) increased, and phase (0.86±0.15 radians at normoxia) decreased significantly in the very-low-frequency range during acute hypoxia (gain, 141%±24% coherence, 136%±29% phase, −25%±22%), which persisted after acclimatization (gain, 136%±36% coherence, 131%±50% phase, −42%±13%), together indicating impaired dynamic cerebral autoregulation in this frequency range. The similarity between both acute and chronic conditions suggests that dynamic cerebral autoregulation is impaired by hypoxia even after successful acclimatization to an extreme high altitude. PMID:20571521

Impaired dynamic cerebral autoregulation at extreme high altitude even after acclimatization.

PubMed

Iwasaki, Ken-ichi; Zhang, Rong; Zuckerman, Julie H; Ogawa, Yojiro; Hansen, Lærke H; Levine, Benjamin David

2011-01-01

Cerebral blood flow (CBF) increases and dynamic cerebral autoregulation is impaired by acute hypoxia. We hypothesized that progressive hypocapnia with restoration of arterial oxygen content after altitude acclimatization would normalize CBF and dynamic cerebral autoregulation. To test this hypothesis, dynamic cerebral autoregulation was examined by spectral and transfer function analyses between arterial pressure and CBF velocity variabilities in 11 healthy members of the Danish High-Altitude Research Expedition during normoxia and acute hypoxia (10.5% O(2)) at sea level, and after acclimatization (for over 1 month at 5,260 m at Chacaltaya, Bolivia). Arterial pressure and CBF velocity in the middle cerebral artery (transcranial Doppler), were recorded on a beat-by-beat basis. Steady-state CBF velocity increased during acute hypoxia, but normalized after acclimatization with partial restoration of SaO(2) (acute, 78% ± 2%; chronic, 89% ± 1%) and progression of hypocapnia (end-tidal carbon dioxide: acute, 34 ± 2 mm Hg; chronic, 21 ± 1 mm Hg). Coherence (0.40 ± 0.05 Units at normoxia) and transfer function gain (0.77 ± 0.13 cm/s per mm Hg at normoxia) increased, and phase (0.86 ± 0.15 radians at normoxia) decreased significantly in the very-low-frequency range during acute hypoxia (gain, 141% ± 24%; coherence, 136% ± 29%; phase, -25% ± 22%), which persisted after acclimatization (gain, 136% ± 36%; coherence, 131% ± 50%; phase, -42% ± 13%), together indicating impaired dynamic cerebral autoregulation in this frequency range. The similarity between both acute and chronic conditions suggests that dynamic cerebral autoregulation is impaired by hypoxia even after successful acclimatization to an extreme high altitude.

Shock Pressures, Temperatures and Durations in L Chondrites: Constraints from Shock-Vein Mineralogy

NASA Astrophysics Data System (ADS)

Xie, Z.; Aramovish Weaver, C.; Decarli, P. S.; Sharp, T. G.

2003-12-01

Shock effects in meteorites provide a record of major impact events on meteorite parent bodies. Shock veins in chondrites, which result from local melting during shock loading, are the location of all high-pressure minerals. Shock veins contain igneous assemblages, produced by the crystallization of shock-induced melt, and metamorphic assemblages, produced by solid-state transformation in entrained host-rock clasts and wall rock. The mineralogy, distribution of high-pressure minerals and microstructures in shock veins provide a record of crystallization pressures and quench histories that can be used to constrain shock pressures and pulse duration. Here we report mineralogical and microstructural studies of shock-induced melt veins in L chondrites that provide insight into the impact history of the L-chondrite parent body. Eight L6 chondrites were investigated using FESEM and TEM and Raman spectroscopy: RC 106 (S6), Tenham (S6), Umbarger (S4-S6), Roy (S3-S5), Ramsdorf (S4), Kunashak (S4), Nakhon Pathon (S4) and La Lande (S4). Igneous melt-vein assemblages, combined with published phase equilibrium data (Agee et al. 1996), indicate crystallization pressures from less than 2.5 GPa for Kunashack and LaLande to approximately 25 GPa for Tenham. Because shock veins quench primarily by thermal conduction, crystallization starts at vein edges and progresses inward. Variation in the igneous assemblage across shock veins, combined with thermal modelling, provides constraints on quench times and pressure variation during quench. Most samples appear to have crystallized prior to shock release, whereas Kunashack and LaLande apparently crystallized after pressure release. RC 106 and Tenham (both S6), which have thick melt veins with uniform igneous assemblages, crystallized under equilibrium shock pressures of approximately 22-25 GPa during shock events that lasted at least 500 ms and 50ms, respectively. The fact that S6 samples do not appear to have crystallized at a pressures greater than about 25 GPa, suggest that the impacts that produced shock veins in chondrites had low relative impact velocities.

Fluid Distribution Pattern in Adult-Onset Congenital, Idiopathic, and Secondary Normal-Pressure Hydrocephalus: Implications for Clinical Care.

PubMed

Yamada, Shigeki; Ishikawa, Masatsune; Yamamoto, Kazuo

2017-01-01

In spite of growing evidence of idiopathic normal-pressure hydrocephalus (NPH), a viewpoint about clinical care for idiopathic NPH is still controversial. A continuous divergence of viewpoints might be due to confusing classifications of idiopathic and adult-onset congenital NPH. To elucidate the classification of NPH, we propose that adult-onset congenital NPH should be explicitly distinguished from idiopathic and secondary NPH. On the basis of conventional CT scan or MRI, idiopathic NPH was defined as narrow sulci at the high convexity in concurrent with enlargement of the ventricles, basal cistern and Sylvian fissure, whereas adult-onset congenital NPH was defined as huge ventricles without high-convexity tightness. We compared clinical characteristics and cerebrospinal fluid distribution among 85 patients diagnosed with idiopathic NPH, 17 patients with secondary NPH, and 7 patients with adult-onset congenital NPH. All patients underwent 3-T MRI examinations and tap-tests. The volumes of ventricles and subarachnoid spaces were measured using a 3D workstation based on T2-weighted 3D sequences. The mean intracranial volume for the patients with adult-onset congenital NPH was almost 100 mL larger than the volumes for patients with idiopathic and secondary NPH. Compared with the patients with idiopathic or secondary NPH, patients with adult-onset congenital NPH exhibited larger ventricles but normal sized subarachnoid spaces. The mean volume ratio of the high-convexity subarachnoid space was significantly less in idiopathic NPH than in adult-onset congenital NPH, whereas the mean volume ratio of the basal cistern and Sylvian fissure in idiopathic NPH was >2 times larger than that in adult-onset congenital NPH. The symptoms of gait disturbance, cognitive impairment, and urinary incontinence in patients with adult-onset congenital NPH tended to progress more slowly compared to their progress in patients with idiopathic NPH. Cerebrospinal fluid distributions and disease progression were significantly different among the patients with adult-onset congenital NPH, idiopathic NPH and secondary NPH. This finding indicates that the pathogenesis of adult-onset congenital NPH may differ from those of idiopathic and secondary NPH. Therefore, adult-onset congenital NPH should be definitively distinguished from the categories of idiopathic and secondary NPH.

Predictors of early neurological deterioration after ischaemic stroke: a case-control study.

PubMed

Barber, Mark; Wright, Fiona; Stott, David J; Langhorne, Peter

2004-01-01

Early neurological deterioration after ischaemic stroke (stroke in progression) is reported to be common and associated with poor outcome or death. The causes of progressing stroke are, however, uncertain. To determine whether prior drug treatment (with anticoagulant or antiplatelet agents) or early adverse physiological features (pyrexia, hypoxia, dehydration or hyperglycaemia) are associated with progressing ischaemic stroke. The study used a case-control design. From a database of 873 consecutive acute stroke admissions, 196 cases of progressing ischaemic stroke (defined by point deterioration in components of the Scandinavian Stroke Scale or death over the first 72 h after hospital admission) were matched to 196 controls on the basis of age and stroke type. Univariate and conditional logistic regression techniques were used to explore predictors of progressing stroke. Cases and controls were well matched for baseline stroke severity. Warfarin use prior to admission was associated with a reduced risk of progressing stroke [odds ratio (OR) 0.10, p = 0.005]. Prior antiplatelet use was not related. A previous history of diabetes (OR 2.11, p = 0.039) and elevated systolic blood pressure on admission (OR 1.01 for each 1 mm Hg rise, p = 0.017) predicted progressing stroke. Although there were no differences in time to presentation or to brain imaging, a visible causative lesion on CT scanning was more common in the progressing stroke group (OR 2.30, p = 0.022). We found no evidence that adverse physiological features were associated with progressing stroke. Outcomes were worse in the progressing stroke group with 70% being dead or dependent by 30 days compared to 55% in the control group (p = 0.002). Prior warfarin use may be protective against progressing ischaemic stroke. A previous history of diabetes along with elevated admission systolic blood pressure predict deterioration. We found no evidence for an association between adverse physiological features and progressing stroke. Copyright 2004 S. Karger AG, Basel

Progress on Pre-Stage Magnetic Coil to Enhance Helicon Mode Excitation and Data Acquisition Software on the Helicon Plasma Experiment (HPX)

NASA Astrophysics Data System (ADS)

Sherman, Justin; Azzari, Phillip; Crilly, P. B.; Duke-Tinson, Omar; James, Royce W.; Karama, Jackson; Page, E. J.; Schlank, Carter; Zuniga, Jonathan

2014-10-01

CGAPL is conducting small investigations in plasma physics and magneto-hydrodynamics buoy positioning. For data management, we are developing capability to analyze/digitize data with a National Instruments Data Acquisition board, 2 MS/s sampling rate (long time scale), and an Express Octopus card, 125 MS/s sampling rate (short scale). Sampling at 12 bits precision, we use LabVIEW as a programing language; GUIs will control variables in 1 or more concurrent runs and monitor of diagnostics. HPX utilizes high density (1013 cm3 up), low pressure (.01 T) Ar gas (fill pressure: on 104 mTorr order). Helicon/W Mode plasmas become a diagnostics test-bed for other investigations and a tool for future spacecraft propulsion devices. Plasmas created by directing energy into gas-filled Pyrex tube; power supply and matching box, up to 250 W power in 20-100 MHz frequencies, provide energy to ignite. Uniform magnetic field needed to reach the W-Mode. We employ an electromagnet to B-field while an acceleration coil positions plasma in vacuum chamber, facilitating analysis. Initial field requirements and accuracy calibration have been completed. Progress on development and implementation of probes and DAQ/GUI system will be reported. Supported by U.S. DEPS Grant [HEL-JTO] PRWJFY13.

The Edgecombe County High Blood Pressure Control Program: I. Correlates of uncontrolled hypertension at baseline.

PubMed Central

Wagner, E H; James, S A; Beresford, S A; Strogatz, D S; Grimson, R C; Kleinbaum, D G; Williams, C A; Cutchin, L M; Ibrahim, M A

1984-01-01

To guide the planning of a multifacetted hypertension control program in Edgecombe County, North Carolina, a baseline survey of a stratified (by township) random sample of 1,000 households was conducted. All adults (greater than or equal to 18 years) were interviewed and had their blood pressures (BP) measured. Five hundred thirty-nine individuals, 27 per cent of the survey population, had diastolic BP greater than or equal to 90 mm Hg or were receiving anti-hypertensive drug therapy. The 539 hypertensives were divided into seven subgroups reflecting successive stages in the control of hypertension based on the awareness, treatment, and control of their hypertension. Unaware hypertensives were further subdivided into three groups according to the recency of their last BP check, and those aware but untreated were subdivided by whether they had previously received treatment. The seven subgroups of hypertensives were compared, separately for women and men, with respect to sociodemographic characteristics, health behaviors, and health status. In general, the progression from undetected hypertension to treatment and control appeared to be associated with being older, female, and White. This progression was further associated with greater educational levels and higher family incomes among women and increasing self-reported morbidity among men. The implications for intervention of these and other described associations are discussed. PMID:6696153

Fluid-Structure Interaction Modeling of Intracranial Aneurysm Hemodynamics: Effects of Different Assumptions

NASA Astrophysics Data System (ADS)

Rajabzadeh Oghaz, Hamidreza; Damiano, Robert; Meng, Hui

2015-11-01

Intracranial aneurysms (IAs) are pathological outpouchings of cerebral vessels, the progression of which are mediated by complex interactions between the blood flow and vasculature. Image-based computational fluid dynamics (CFD) has been used for decades to investigate IA hemodynamics. However, the commonly adopted simplifying assumptions in CFD (e.g. rigid wall) compromise the simulation accuracy and mask the complex physics involved in IA progression and eventual rupture. Several groups have considered the wall compliance by using fluid-structure interaction (FSI) modeling. However, FSI simulation is highly sensitive to numerical assumptions (e.g. linear-elastic wall material, Newtonian fluid, initial vessel configuration, and constant pressure outlet), the effects of which are poorly understood. In this study, a comprehensive investigation of the sensitivity of FSI simulations in patient-specific IAs is investigated using a multi-stage approach with a varying level of complexity. We start with simulations incorporating several common simplifications: rigid wall, Newtonian fluid, and constant pressure at the outlets, and then we stepwise remove these simplifications until the most comprehensive FSI simulations. Hemodynamic parameters such as wall shear stress and oscillatory shear index are assessed and compared at each stage to better understand the sensitivity of in FSI simulations for IA to model assumptions. Supported by the National Institutes of Health (1R01 NS 091075-01).

Self-pinched lithium beam transport experiments on SABRE

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

Hanson, D.L.; Olson, C.L.; Poukey, J.W.

Self-pinched transport of ion beams has many advantages for ion-driven ICF applications involving high yield and energy production. The authors are currently preparing for a self-pinched lithium beam transport experiment on the SABRE accelerator. There are three transport elements that must eventually be demonstrated: (1) efficient lithium beam generation and ballistic transport to a focus at the self-pinched transport channel entrance; (2) self-pinched transport in the channel, requiring optimized injection conditions and gas breakdown; and (3) self-pinched transport of the equilibrated beam from the channel into free space, with associated aiming and stability considerations. In the present experiment, a hollowmore » annular lithium beam from an applied-B extraction ion diode will be focused to small radius (r {le} 2 cm) in a 60 cm long ballistic focus section containing argon gas at a pressure of a few Torr. The self-pinched transport channel will contain a low pressure background gas of 10--40 mTorr argon to allow sufficient net current to confine the beam for long distance transport. IPROP simulations are in progress to optimize the design of the ballistic and self-pinched transport sections. Progress on preparation of this lithium self-pinched transport experiment, including a discussion of transport system design, important gas breakdown issues, and diagnostics, will be presented.« less

Straight A's: Public Education Policy and Progress. Volume 11, Number 7

ERIC Educational Resources Information Center

Amos, Jason, Ed.

2011-01-01

"Straight A's: Public Education Policy and Progress" is a biweekly newsletter that focuses on education news and events both in Washington, DC and around the country. The following articles are included in this issue: (1) FY 2011 Spending Discussions Continue: Pressure Mounts as April 8 Deadline Approaches and Possibility of Government Shutdown…

Protecting the retinal neurons from glaucoma: lowering ocular pressure is not enough.

PubMed

Pascale, Alessia; Drago, Filippo; Govoni, Stefano

2012-07-01

The retina is theater of a number of biochemical reactions allowing, within its layers, the conversion of light impulses into electrical signals. The axons of the last neuronal elements, the ganglion cells, form the optic nerve and transfer the signals to the brain. Therefore, an appropriate cellular communication, not only within the different retinal cells, but also between the retina itself and the other brain structures, is fundamental. One of the most diffuse pathologies affecting retinal function and communication, which thus reverberates in the whole visual system, is glaucoma. This insidious disease is characterized by a progressive optic nerve degeneration and sight loss which may finally lead to irreversible blindness. Nevertheless, the progressive nature of this pathology offers an opportunity for therapeutic intervention. To better understand the cellular processes implicated in the development of glaucoma useful to envision a targeted pharmacological strategy, this manuscript first examines the complex cellular and functional organization of the retina and subsequently identifies the targets sensitive to neurodegeneration. Within this context, high ocular pressure represents a key risk factor. However, recent literature findings highlight the concept that lowering ocular pressure is not enough to prevent/slow down glaucomatous damage, suggesting the importance of combining the hypotensive treatment with other pharmacological approaches, such as the use of neuroprotectants. Therefore, this important and more novel aspect is extensively considered in this review, also emphasizing the idea that the neuroprotective strategy should be extended to the entire visual system and not restricted to the retina. Copyright © 2012 Elsevier Ltd. All rights reserved.

Influence of acute progressive hypoxia on cardiovascular variability in conscious spontaneously hypertensive rats

PubMed Central

Sugimura, Mitsutaka; Hirose, Yohsuke; Hanamoto, Hiroshi; Okada, Kenji; Boku, Aiji; Morimoto, Yoshinari; Taki, Kunitaka; Niwa, Hitoshi

2008-01-01

The purpose of this study is to examine the influence of acute progressive hypoxia on cardiovascular variability and striatal dopamine (DA) levels in conscious, spontaneously hypertensive rats (SHR) and Wistar Kyoto rats (WKY). After preparation for measurement, the inspired oxygen concentration of rats was decreased to 10% within 5 min (descent stage), maintained at 10% for 10 min (fixed stage), and then elevated back to 20% over 5 min (recovery stage). The systolic blood pressure (SBP) and heart rate (HR) variability at each stage was calculated to evaluate the autonomic nervous system response using the wavelet method. Striatal DA during each stage was measured using in vivo microdialysis. We found that SHR showed a more profound hemodynamic response to progressive hypoxia as compared to WKY. Cardiac parasympathetic activity in SHR was significantly inhibited by acute progressive hypoxia during all stages, as shown by the decrease in the high frequency band of HR variability (HR-HF), along with transient increase in sympathetic activity during the early hypoxic phase. This decrease in the HR-HF continued even when SBP was elevated. Striatal DA levels showed the transient similar elevation in both groups. These findings suggest that acute progressive hypoxic stress in SHR inhibits cardiac parasympathetic activity through reduction of baroreceptor reflex sensitivity, with potentially severe deleterious effects on circulation, in particular on HR and circulatory control. Furthermore, it is thought that the influence of acute progressive hypoxia on striatal DA levels is similar in SHR and WKY. PMID:18599365

[Quantitative evaluation of resource and environment pressure in Qinghai Province, China based on footprint family].

PubMed

Ma, Cai Hong; Zhao, Jing

2016-04-22

In order to effectively evaluate the influence of human activities on the resource and environment, this paper constructed an resource and environment pressure evaluation system based on footprint family, and calculated the ecological footprint, carbon footprint, water footprint, and resource and environment pressure in Qinghai Province. The results showed that from 1990 to 2013, the ecological footprint per capita in Qinghai Province increased from 1.32 hm 2 to 3.32 hm 2 , and biological capacity per capita decreased from 2.33 hm 2 to 2.07 hm 2 . Since 2006 there was ecological deficit. However, the biomass surplus existed during 1990-2013. The carbon footprint per capita increased from 5.82 t to 15.85 t, which had been more than 7.93 times of the target to address climate change. The water footprint per capita decreased from 967.67 m 3 to 732.05 m 3 . Since 1990, the ecological pressure was at low grade (1 b ), greenhouse gas (GHG) emissions pressure was enhanced from low grade (1 b ) to above-average grade (2 b ), the water pressure was at very low grade (1 a ), the resource and environment pressure increased from very low grade (1 a ) to low grade (1 b ). The rate of contribution of ecological pressure and water resource pressure to resources and environment pressure gradually decreased, whereas, the rate of contribution of GHG emission pressure to resources and environment pressure gradually increased. The resource and environment pressure had spatial heterogeneity. In 2013, it was at very high grade (3 b ) in Xining City, at above-average grade (2 b ) in Haidong City, at below-average grade (2 a ) in Haixi State and atvery low grade (1 a ) in the rest regions. The main resource and environment pressure source also had obvious spatial heterogeneity. In future, differentiation strategies should be taken in the decompression progress.

Effectiveness of home-based cupping massage compared to progressive muscle relaxation in patients with chronic neck pain--a randomized controlled trial.

PubMed

Lauche, Romy; Materdey, Svitlana; Cramer, Holger; Haller, Heidemarie; Stange, Rainer; Dobos, Gustav; Rampp, Thomas

2013-01-01

Chronic neck pain is a major public health problem with very few evidence-based complementary treatment options. This study aimed to test the efficacy of 12 weeks of a partner-delivered home-based cupping massage, compared to the same period of progressive muscle relaxation in patients with chronic non-specific neck pain. Patients were randomly assigned to self-directed cupping massage or progressive muscle relaxation. They were trained and asked to undertake the assigned treatment twice weekly for 12 weeks. Primary outcome measure was the current neck pain intensity (0-100 mm visual analog scale; VAS) after 12 weeks. Secondary outcome measures included pain on motion, affective pain perception, functional disability, psychological distress, wellbeing, health-related quality of life, pressure pain thresholds and adverse events. Sixty one patients (54.1±12.7 years; 73.8%female) were randomized to cupping massage (n = 30) or progressive muscle relaxation (n = 31). After treatment, both groups showed significantly less pain compared to baseline however without significant group differences. Significant effects in favor of cupping massage were only found for wellbeing and pressure pain thresholds. In conclusion, cupping massage is no more effective than progressive muscle relaxation in reducing chronic non-specific neck pain. Both therapies can be easily used at home and can reduce pain to a minimal clinically relevant extent. Cupping massage may however be better than PMR in improving well-being and decreasing pressure pain sensitivity but more studies with larger samples and longer follow-up periods are needed to confirm these results. ClinicalTrials.gov NCT01500330.

Effectiveness of Home-Based Cupping Massage Compared to Progressive Muscle Relaxation in Patients with Chronic Neck Pain—A Randomized Controlled Trial

PubMed Central

Lauche, Romy; Materdey, Svitlana; Cramer, Holger; Haller, Heidemarie; Stange, Rainer; Dobos, Gustav; Rampp, Thomas

2013-01-01

Chronic neck pain is a major public health problem with very few evidence-based complementary treatment options. This study aimed to test the efficacy of 12 weeks of a partner-delivered home-based cupping massage, compared to the same period of progressive muscle relaxation in patients with chronic non-specific neck pain. Patients were randomly assigned to self-directed cupping massage or progressive muscle relaxation. They were trained and asked to undertake the assigned treatment twice weekly for 12 weeks. Primary outcome measure was the current neck pain intensity (0–100 mm visual analog scale; VAS) after 12 weeks. Secondary outcome measures included pain on motion, affective pain perception, functional disability, psychological distress, wellbeing, health-related quality of life, pressure pain thresholds and adverse events. Sixty one patients (54.1±12.7 years; 73.8%female) were randomized to cupping massage (n = 30) or progressive muscle relaxation (n = 31). After treatment, both groups showed significantly less pain compared to baseline however without significant group differences. Significant effects in favor of cupping massage were only found for wellbeing and pressure pain thresholds. In conclusion, cupping massage is no more effective than progressive muscle relaxation in reducing chronic non-specific neck pain. Both therapies can be easily used at home and can reduce pain to a minimal clinically relevant extent. Cupping massage may however be better than PMR in improving well-being and decreasing pressure pain sensitivity but more studies with larger samples and longer follow-up periods are needed to confirm these results. Trial Registration ClinicalTrials.gov NCT01500330 PMID:23762355

Automated assessment of noninvasive filling pressure using color Doppler M-mode echocardiography

NASA Technical Reports Server (NTRS)

Greenberg, N. L.; Firstenberg, M. S.; Cardon, L. A.; Zuckerman, J.; Levine, B. D.; Garcia, M. J.; Thomas, J. D.

2001-01-01

Assessment of left ventricular filling pressure usually requires invasive hemodynamic monitoring to follow the progression of disease or the response to therapy. Previous investigations have shown accurate estimation of wedge pressure using noninvasive Doppler information obtained from the ratio of the wave propagation slope from color M-mode (CMM) images and the peak early diastolic filling velocity from transmitral Doppler images. This study reports an automated algorithm that derives an estimate of wedge pressure based on the spatiotemporal velocity distribution available from digital CMM Doppler images of LV filling.

Progressive Damage and Fracture of Unstiffened and Stiffened Composite Pressure Vessels

NASA Technical Reports Server (NTRS)

Minnetyan, Levon; Gotsis, Pascal K.; Chamis, Christos C.

1997-01-01

Structural durability and damage tolerance characteristics of pressurized graphite/epoxy laminated thin composite cylinders are investigated via computational simulation. Both unstiffened and integral hoop stiffened cylinders are considered. A computer code is utilized for the simulation of composite structural degradation under loading. Damage initiation, growth, accumulation, and propagation to structural fracture are included in the simulation. The increase of burst pressure due to hoop stiffening is quantified. Results demonstrate the significance of the type and size of local defects on the structural durability of pressurized composite cylindrical shells.

Twelve shifting paradigms in diabetic renal disease and hypertension.

PubMed

Mogensen, Carl Erik

2008-11-13

In the last 30 years we have seen considerable progress in the management of patients with diabetes, in particular with diabetic renal disease. A number of paradigms have been broken down, namely the following, as a consequence, clinical care has improved dramatically. . Significant renal involvement and albuminuria is rare in patients with essential hypertension. 2. High GFR is good for prognosis. 3. Only proteinuric diabetic patients have a poor prognosis. 4. Microalbuminuria only predicts renal disease. 5. Reducing blood pressure may cause low perfusion in the kidney and other organs with long-term negative effect, especially on the glomerular filtration rate. 6. Only in the presence of high blood pressure, should microalbuminuric patients receive anti-hypertensive treatment, including blockade of the RAS. 7. Only reducing blood pressure by blocking RAS in diabetes is relevant and justified. 8. Normoalbuminuria as indicated in the present definition is 'normal'. 9. ACE-I or ARB can only be used separately. 10. Diastolic blood pressure and later systolic pulse pressure are the best parameters for blood pressure recording. 11. Microalbuminuria is the strongest risk marker in patients with type 1 diabetes. 12. Screening for microalbuminuria is relevant, but follow-up was not proposed (also regarding microalbuminuria). In the present situation, it is well-known that patients with essential hypertension may sometimes have microalbuminuria, and it is known that it predicts a poor prognosis. Interestingly, in type 1 diabetes, hyperfiltration is a marker for poor prognosis related to metabolic control. Thus hyperfiltration is a marker for bad development, but microalbuminuria (below the proteinuric level) is also associated with a poor prognosis. It was originally believed that microalbuminuria only predicts renal disease. However, surprisingly it predicts as well cardiovascular disease and early mortality. The story about blood pressure and progression of renal disease is interesting, because it was earlier believed that a certain high blood pressure was mandatory for preservation of the renal function. This appeared to be a completely wrong concept. The data regarding microalbuminuria suggest that patients with microalbuminuria should receive anti-hypertensive treatment, even patients with so-called normal blood pressure. This was confirmed in several trials and also included in the guidelines. Reducing blood pressure is important, but it appeared to be especially beneficial to block the renin-angiontensin system, and it is clear that albuminuria is a continuous variable and is also a risk factor. Earlier it was suggested to use ACE-inhibitors or ARBs. Now it is clear that it is possible to use a combination, with good theoretical background. In the history of hypertension, it was earlier believed that diastolic blood pressure was most important, but later on it was generally accepted that systolic is a better predictor and the goal for treatment and pulse pressure may be even better. Not only is microalbuminuria an important risk marker, but it is as well clear that regression of microalbuminuria is a good marker for a better prognosis in patients. Microalbuminuria is believed to be the strongest risk factor, but new studies actually suggest that a simple parameter such as self-rated health is crucial along with other factors. Regarding new developments, it is clear that new studies have led to several advancements in management in patients, for instance the Steno II study shows positive effect on mortality by multifactorial intervention. Similarly, the ADVANCE study also showed positive effect on mortality by more intensified anti-hypertensive treatment with an ACE-inhibitor. We are eagerly awaiting the results from glucose arm in the ADVANCE study, especially in the light of the ACCORD study showing increased mortality with too strict glycemic control with a goal of 6% in HbA1c.

Gas storage, transport and pressure changes in an evolving permeable volcanic edifice

NASA Astrophysics Data System (ADS)

Collinson, A. S. D.; Neuberg, J. W.

2012-10-01

The total volume of gas in a magma, dissolved and subsequently exsolved, greatly influences the degree of explosiveness of a volcanic system. There is a marked contrast between the behaviour of a volcano in an "open" system compared to one which is "closed". It is therefore essential to understand the entire degassing process: gas transport, storage and loss. A particular focus of this study is the effect different permeabilities and pressure gradients within a volcanic edifice have on the degree and pattern of the gas velocity. Gas loss is modelled numerically in two dimensions using a finite element approach, which allows the specification of boundary conditions with respect to pressure and different permeability domains within the volcanic edifice. By combining the time-dependent continuity equation and Darcy's law, a partial differential equation is derived and solved for the pressure. The associated pressure gradient is then used within Darcy's law to determine the corresponding gas velocity distribution. This method is used not only for stationary systems in equilibrium, but also as a time-dependent progression. It permits the modelling of different situations to study how various volcanic characteristics affect the gas loss. The model is used to investigate the change in pressure and gas in response to time-dependent scenarios. These are a dome collapse or sudden increase in permeability by magma rupture at the conduit margin, the formation of cracks within the lava dome and sealing by crystallisation. Our results show that a combination of high and low permeability regions is required for effective gas storage. High permeability allows the gas to enter the system, but impermeable areas act to confine the gas, thereby increasing its pressure and consequently, increasing the amount of gas which may be dissolved in the melt. Furthermore, our results show that permeability is an essential factor influencing the response time to system changes, which could be linked in future to deformation and other geophysical observations. Our model is highly versatile and sheds new light on the understanding of gas storage and transport in a permeable volcanic edifice.

APS 6BM-B Large Volume High Pressure Beamline: A Workhorse for Rock and Mineral Physics

NASA Astrophysics Data System (ADS)

Chen, H.; Whitaker, M. L.; Baldwin, K. J.; Huebsch, W. R.; Vaughan, M. T.; Weidner, D. J.

2017-12-01

With the inheritance of decades of technical innovations at the NSLS X17B2 Beamline, APS 6BM-B Beamline was established in 2015 and is a dedicated beamline for synchrotron-based large volume high pressure research in earth sciences, especially rock and mineral physics. Currently a 250-ton hydraulic press equipped with a D-DIA module is installed and a Rotational Drickamer Apparatus from Yale University is hosted every cycle, covering a pressure range from crust to lower mantle. 6BM-B operates in white beam mode with an effective energy range of 20-100 keV. Energy dispersive X-ray diffraction data is collected using a 10-element solid state Ge array detector arranged in a circular geometry to allow for the real time assessment of stress. Direct radiographic imaging using Prosillica CCD camera and scintillating YAG crystals yields sample strain and strain rate. In addition to applications in phase transitions, equation of states measurements, sound velocity measurements, this setup is ideal for studies of steady state and dynamic deformation process. In this presentation, technical features and strengths of 6BM-B will be discussed. Most recent progress and science highlights of our user community will be showcased.

Diamond-anvil high-pressure cell with improved X-ray collimation system

DOEpatents

Schiferl, David; Olinger, Barton W.; Livingston, Robert W.

1986-01-01

An adjustable X-ray collimation system for a diamond-anvil high-pressure cell of the type including a cooperable piston and cylinder and a pair of opposing diamonds located between the head of the piston and the head of the cylinder. The X-ray collimation system includes a tubular insert which contains an X-ray collimator. The insert is engageable in the bore of the piston. The collimator is mounted within the insert by means of an elastomeric O-ring at the end closest the opposed diamonds, and by means of a set of adjustable set screws at the opposite end. By adjustment of the set screws the collimator can be pivoted about the O-ring and brought into alignment with the opposed diamonds and the sample contained therein. In the preferred embodiment there is further provided a set of plugs which are insertable in the bore of the collimator. The plugs have bores of different diameters. By successively inserting plugs of progressively smaller bore diameters and adjusting the alignment of the collimator with each plug, the collimator can be quickly brought into accurate alignment with the diamonds. The collimation system allows alignment of the collimator either before or after the cell has been loaded and pressurized.

Exploration to generate atmospheric pressure glow discharge plasma in air

NASA Astrophysics Data System (ADS)

Wenzheng, LIU; Chuanlong, MA; Shuai, ZHAO; Xiaozhong, CHEN; Tahan, WANG; Luxiang, ZHAO; Zhiyi, LI; Jiangqi, NIU; Liying, ZHU; Maolin, CHAI

2018-03-01

Atmospheric pressure glow discharge (APGD) plasma in air has high application value. In this paper, the methods of generating APGD plasma in air are discussed, and the characteristics of dielectric barrier discharge (DBD) in non-uniform electric field are studied. It makes sure that APGD in air is formed by DBD in alternating current electric field with using the absorbing electron capacity of electret materials to provide initial electrons and to end the discharge progress. Through designing electric field to form two-dimensional space varying electric field and three-dimensional space varying electric field, the development of electron avalanches in air-gap is suppressed effectively and a large space of APGD plasma in air is generated. Further, through combining electrode structures, a large area of APGD plasma in air is generated. On the other hand, by using the method of increasing the density of initial electrons, millimeter-gap glow discharge in atmospheric pressure air is formed, and a maximum gap distance between electrodes is 8 mm. By using the APGD plasma surface treatment device composed of contact electrodes, the surface modification of high polymer materials such as aramid fiber and polyester are studied and good effect of modifications is obtained. The present paper provides references for the researchers of industrial applications of plasma.

Diamond-anvil high-pressure cell with improved x-ray collimation system

DOEpatents

Schiferl, D.; Olinger, B.W.; Livingston, R.W.

1984-03-30

An adjustable x-ray collimation system for a diamond-anvil high-pressure cell of the type including a cooperable piston and cylinder and a pair of opposing diamonds located between the head of the piston and the head of the cylinder. The x-ray collimation system includes a tubular insert which contains an x-ray collimator. The insert is engageable in the bore of the piston. The collimator is mounted within the insert by means of an elastomeric o-ring at the end closest the opposed diamonds, and by means of a set of adjustable set screws at the opposite end. By adjustment of the set screws the collimator can be pivoted about the o-ring and brought into alignment with the opposed diamonds and the sample contained therein. In the preferred embodiment there is further provided a set of plugs which are insertable in the bore of the collimator. The plugs have bores of different diameters. By successively inserting plugs of progressively smaller bore diameters and adjusting the alignment of the collimator with each plug, the collimator can be quickly brought into accurate alignment with the diamonds. The collimation system allows alignment of the collimator either before or after the cell has been loaded and pressurized.

Multifidelity, multidisciplinary optimization of turbomachines with shock interaction

NASA Astrophysics Data System (ADS)

Joly, Michael Marie

Research on high-speed air-breathing propulsion aims at developing aircraft with antipodal range and space access. Before reaching high speed at high altitude, the flight vehicle needs to accelerate from takeoff to scramjet takeover. Air turbo rocket engines combine turbojet and rocket engine cycles to provide the necessary thrust in the so-called low-speed regime. Challenges related to turbomachinery components are multidisciplinary, since both the high compression ratio compressor and the powering high-pressure turbine operate in the transonic regime in compact environments with strong shock interactions. Besides, lightweight is vital to avoid hindering the scramjet operation. Recent progress in evolutionary computing provides aerospace engineers with robust and efficient optimization algorithms to address concurrent objectives. The present work investigates Multidisciplinary Design Optimization (MDO) of innovative transonic turbomachinery components. Inter-stage aerodynamic shock interaction in turbomachines are known to generate high-cycle fatigue on the rotor blades compromising their structural integrity. A soft-computing strategy is proposed to mitigate the vane downstream distortion, and shown to successfully attenuate the unsteady forcing on the rotor of a high-pressure turbine. Counter-rotation offers promising prospects to reduce the weight of the machine, with fewer stages and increased load per row. An integrated approach based on increasing level of fidelity and aero-structural coupling is then presented and allows achieving a highly loaded compact counter-rotating compressor.

Management of diabetic nephropathy: Recent progress and future perspective.

PubMed

Ahmad, Jamal

2015-01-01

Diabetic nephropathy (DN), a leading cause of end-stage renal disease (ESRD) affecting ∼20-30% diabetics, is associated with increased cardiovascular mortality. The progression of kidney disease in patients with diabetes can take many years. It occurs as a result of interaction between both genetic and environmental factors in individuals with both type 1 and type 2 diabetes. Hyperglycaemia, hypertension, and genetic pre-disposition are the main risk factors besides elevated serum lipids, smoking habits, and the amount of dietary proteins. Interventions such as glycaemic control, blood pressure control and inhibition of the renin-angiotensin-aldosterone system have been shown to slow this progression. Despite the implementation of these strategies, the number of patients with diabetes that ultimately develop end-stage renal disease remains high. The treatment of DN, therefore, has posed a formidable challenge besides optimization of renin-angiotensin-aldosterone system blockade in patients with DN; additional investigation has focused on the potential of novel therapies that target various pathways upregulated by hyperglycaemia or other targets believed to promote the progression of DN such as oxidative stress, inflammation, endothelin system and vitamin D receptors. This review article addresses the pathogenesis and some of the well established principles regarding the progression and accepted management of DN, and also includes the perspectives of novel anti-DN agents and the future directions for the prevention of DN. Copyright © 2015 Diabetes India. Published by Elsevier Ltd. All rights reserved.

Computational Simulation of Damage Progression of Composite Thin Shells Subjected to Mechanical Loads

NASA Technical Reports Server (NTRS)

Gotsis, P. K.; Chamis, C. C.; Minnetyan, L.

1996-01-01

Defect-free and defected composite thin shells with ply orientation (90/0/+/-75) made of graphite/epoxy are simulated for damage progression and fracture due to internal pressure and axial loading. The thin shells have a cylindrical geometry with one end fixed and the other free. The applied load consists of an internal pressure in conjunction with an axial load at the free end, the cure temperature was 177 C (350 F) and the operational temperature was 21 C (70 F). The residual stresses due to the processing are taken into account. Shells with defect and without defects were examined by using CODSTRAN an integrated computer code that couples composite mechanics, finite element and account for all possible failure modes inherent in composites. CODSTRAN traces damage initiation, growth, accumulation, damage propagation and the final fracture of the structure. The results show that damage initiation started with matrix failure while damage/fracture progression occurred due to additional matrix failure and fiber fracture. The burst pressure of the (90/0/+/- 75) defected shell was 0.092% of that of the free defect. Finally the results of the damage progression of the (90/0/+/- 75), defective composite shell was compared with the (90/0/+/- theta, where theta = 45 and 60, layup configurations. It was shown that the examined laminate (90/0/+/- 75) has the least damage tolerant of the two compared defective shells with the (90/0/+/- theta), theta = 45 and 60 laminates.

Orienting Schools toward Equity: Subgroup Accountability Pressure and School-Level Responses

ERIC Educational Resources Information Center

Garver, Rachel

2017-01-01

This article examines school-level responses to subgroup accountability pressure through an ethnographic case study of a school cited for failing to make adequate yearly progress for student subgroups. Concerns about the calculations and measures used to derive the citation and reservations about acting on accountability data delegitimized the…

Accountability Pressure and Non-Achievement Student Behaviors. Working Paper 122

ERIC Educational Resources Information Center

Holbein, John B.; Ladd, Helen F.

2015-01-01

In this paper we examine how failing to make adequate yearly progress under No Child Left Behind (NCLB), and the accountability pressure that ensues, affects various non-achievement student behaviors. Using administrative data from North Carolina and leveraging a discontinuity in the determination of school failure, we examine the causal impact of…

Progressive and cumulative fabric effects of multiple hydroentangling impacts at different water pressures on greige cotton substrate

USDA-ARS?s Scientific Manuscript database

A practical study was conducted to determine the effects of the hydroentangling jet strip’s orifice size and the hydroentangling water pressure on the energy expended and the properties of the resulting nonwoven fabrics produced on a commercial-grade hydro-entanglement (HE) system, using greige cott...

Quaternary Sediment Accumulation in the Aleutian Trench: Implications for Dehydration Reaction Progress and Pore Pressure Development Offshore Alaska

NASA Astrophysics Data System (ADS)

Meridth, L. N.; Screaton, E.; Jaeger, J. M.; James, S. R.; Villaseñor, T. G.

2015-12-01

Sediment inputs to subduction zones impart a significant control on diagenetic reaction progress, fluid production and pore pressure development and thus affect hydrologic and tectonic behavior during subduction. Intensified glaciation following the mid-Pleistocene transition increased sediment flux to the Gulf of Alaska. Rapid sediment accumulation (>1 km/my) in the Aleutian Trench increases overburden and should accelerate dehydration of hydrous sedimentary components by elevating temperatures in the incoming sediment column. These processes have the potential to generate fluid overpressures in the mud-dominated, low permeability sediments deposited on the incoming plate, offshore SE Alaska. Mineralogical analyses on incoming sediments from Deep Sea Drilling Project Leg 18 and Integrated Ocean Drilling Program Expedition 341 show that both smectite and Opal-A are present as hydrous mineral phases. A 1-D numerical model was developed to track dehydration reaction progress and pore pressures in the incoming sediment column from the abyssal plain to the Aleutian Trench. Simulated temperatures in the incoming column increase due to the insulating effect of trench sediments. As a result, trench sedimentation causes smectite dehydration to begin and Opal-A dehydration to nearly reach completion at the deformation front. Simulated excess pore pressures in the proto-decollement zone increase from nearly hydrostatic to almost half of lithostatic due to the rapid deposition of trench sediments. The 1-D modeling results were incorporated into a 2-D model that follows the underthrust column at the deformation front into the subduction zone. Simulated results of the 2-D flow model illustrate the effects of lateral flow on pore pressure distribution following subduction.

Mononuclear Phagocytes Are Dispensable for Cardiac Remodeling in Established Pressure-Overload Heart Failure

PubMed Central

Patel, Bindiya; Ismahil, Mohamed Ameen; Hamid, Tariq; Bansal, Shyam S.; Prabhu, Sumanth D.

2017-01-01

Background Although cardiac and splenic mononuclear phagocytes (MPs), i.e., monocytes, macrophages and dendritic cells (DCs), are key contributors to cardiac remodeling after myocardial infarction, their role in pressure-overload remodeling is unclear. We tested the hypothesis that these immune cells are required for the progression of remodeling in pressure-overload heart failure (HF), and that MP depletion would ameliorate remodeling. Methods and Results C57BL/6 mice were subjected to transverse aortic constriction (TAC) or sham operation, and assessed for alterations in MPs. As compared with sham, TAC mice exhibited expansion of circulating LyC6hi monocytes and pro-inflammatory CD206− cardiac macrophages early (1 w) after pressure-overload, prior to significant hypertrophy and systolic dysfunction, with subsequent resolution during chronic HF. In contrast, classical DCs were expanded in the heart in a biphasic manner, with peaks both early, analogous to macrophages, and late (8 w), during established HF. There was no significant expansion of circulating DCs, or Ly6C+ monocytes and DCs in the spleen. Periodic systemic MP depletion from 2 to 16 w after TAC in macrophage Fas-induced apoptosis (MaFIA) transgenic mice did not alter cardiac remodeling progression, nor did splenectomy in mice with established HF after TAC. Lastly, adoptive transfer of splenocytes from TAC HF mice into naïve recipients did not induce immediate or long-term cardiac dysfunction in recipient mice. Conclusions Mononuclear phagocytes populations expand in a phasic manner in the heart during pressure-overload. However, they are dispensable for the progression of remodeling and failure once significant hypertrophy is evident and blood monocytosis has normalized. PMID:28125666

Chronic Inflammatory Demyelinating Polyneuropathy Manifesting as Neuropathy With Liability to Pressure Palsies: A Case Report.

PubMed

Shah, Akshay; Rison, Richard A; Beydoun, Said R

2015-12-01

Chronic inflammatory demyelinating polyneuropathy (CIDP) is a progressive demyelinating neuropathy, which typically presents with proximal and distal neuropathic symptoms and is typically responsive to immunomodulatory therapies. Many variants have been subsequently described in the literature and have similarly shown to be responsive to immunotherapy. We present a case of a 43-year-old Middle Eastern/Arabic man presenting with symptoms of mixed sensorimotor neuropathy most evident at entrapment sites mimicking hereditary neuropathy with liability to pressure palsies. His electrodiagnostic study revealed features of acquired demyelinating neuropathy and a negative genetic workup. Alternative diagnosis of CIDP was considered in the context of symptomatic disease progression, negative genetic workup, and electrodiagnosis leading to initiation of immunotherapy with intravenous immunoglobulins. His neuropathy responded confirming our diagnosis of an inflammatory demyelinating polyneuropathy. We describe a previously unknown variant of CIDP with phenotypic characteristics of hereditary neuropathy with liability to pressure palsies and its potential for successful treatment with intravenous immunoglobulins. This case illustrates an unusual presentation of CIDP mimicking hereditary neuropathy with liability to pressure palsies.

Time-dependent effects of intermittent hydrostatic pressure on articular chondrocyte type II collagen and aggrecan mRNA expression.

PubMed

Smith, R L; Lin, J; Trindade, M C; Shida, J; Kajiyama, G; Vu, T; Hoffman, A R; van der Meulen, M C; Goodman, S B; Schurman, D J; Carter, D R

2000-01-01

The normal loading of joints during daily activities causes the articular cartilage to be exposed to high levels of intermittent hydrostatic pressure. This study quantified effects of intermittent hydrostatic pressure on expression of mRNA for important extracellular matrix constituents. Normal adult bovine articular chondrocytes were isolated and tested in primary culture, either as high-density monolayers or formed aggregates. Loaded cells were exposed to 10 MPa of intermittent hydrostatic pressure at a frequency of 1 Hz for periods of 2, 4, 8, 12, and 24 hrs. Other cells were intermittently loaded for a period of 4 hrs per day for 4 days. Semiquantitative reverse transcription polymerase chain reaction assays were used to assess mRNA signal levels for collagen types II and I and aggrecan. The results showed that type II collagen mRNA signal levels exhibited a biphasic pattern, with an initial increase of approximately five-fold at 4 and 8 hrs that subsequently decreased by 24 hrs. In contrast, aggrecan mRNA signal increased progressively up to three-fold throughout the loading period. Changing the loading profile to 4 hrs per day for 4 days increased the mRNA signal levels for type II collagen nine-fold and for aggrecan twenty-fold when compared to unloaded cultures. These data suggest that specific mechanical loading protocols may be required to optimally promote repair and regeneration of diseased joints.

Coronary aneurysms in a child: an unusual presentation of pseudovasculitis.

PubMed

Seguro, Luciana P C; Freire de Carvalho, Jozelio; Lianza, Alessandro C; Pereira, Rosa M R

2013-01-01

Abnormalities of the coronary arteries in children are rare and Kawasaki disease is the most common cause of acquired coronary disease in a paediatric population. We report a case of a female child with coronary artery aneurysms and convulsions, who was diagnosed with Kawasaki disease. Due to systemic arterial hypertension and persistence of high inflammatory markers after treatment with high dose glucocorticoid and intravenous immunoglobulin, further investigation was performed and revealed a pheochromocytoma. Surgical removal led to normalization of blood pressure and laboratory parameters. Periodic echocardiography studies revealed progressive reduction of coronary aneurysms, with complete normalisation after 8 months. This is the first case described of coronary aneurysms presenting as a pseudovasculitis syndrome associated with pheochromocytoma.

Progress in Ion Transport Membranes for Gas Separation Applications

NASA Astrophysics Data System (ADS)

Bose, Arun C.; Stiegel, Gary J.; Armstrong, Phillip A.; Halper, Barry J.; (Ted) Foster, E. P.

This chapter describes the evolution and advances of ion transport membranes for gas separation applications, especially separation of oxygen from air. In partnership with the US Department of Energy (DOE), Air Products and Chemicals, Inc. (Air Products) successfully developed a novel class of mixed ion-electron conducting materials and membrane architecture. These novel materials are referred to as ion transport membranes (ITM). Generically, ITMs consist of modified perovskite and brownmillerite oxide solid electrolytes and provide high oxygen anion and electron conduction typically at high temperatures driven by an oxygen potential gradient without the need for external power. The partial pressure ratio across the ITM layer creates the driving force for oxygen separation.

Split-shot sinker facilitates seton treatment of anal fistulae.

PubMed

Awad, M L; Sell, H W; Stahlfeld, K R

2009-06-01

The cutting seton is an inexpensive and effective method of treating high complex perianal fistulae. Following placement of the seton, advancement through the external sphincter muscles requires progressive tightening of the seton. The requirement for maintaining the appropriate tension and onset of perianal pressure necrosis are problems frequently encountered using this technique. Using a 3-0 polypropylene suture, a red-rubber catheter, and a nontoxic tin split-shot sinker, we minimized or eliminated these problems. We initially used this technique in one patient with satisfactory results. This technique is technically easy, safe, inexpensive, and efficient, and we are using it in all patients with high perianal fistulae who require a seton.

[Psychological approaches in hypertension management].

PubMed

Abgrall-Barbry, Gaëlle; Consoli, Silla M

2006-06-01

Stress factors, especially high levels of occupational stress, are associated with hypertension. Several so-called psychological techniques have been applied to hypertension: biofeedback, relaxation techniques (Schultz' autogenic training, Jacobson's progressive relaxation), transcendental meditation, and cognitive behavioral techniques for stress management. Randomized studies show that the best results come from cognitive behavioral methods, whether or not they include relaxation techniques. Other forms of psychotherapy (such as psychoanalysis) may be useful, although their benefits for blood pressure have not been tested in controlled trials. Patients should be informed about the personal benefits they may obtain from psychological treatment. Indications are hyperreactivity to stress, high levels of occupational stress, and difficulty in tolerating or complying with antihypertensive drugs.

Simulating the Impact of Improved Cardiovascular Risk Interventions on Clinical and Economic Outcomes in Russia

PubMed Central

Shum, Kenny; Alperin, Peter; Shalnova, Svetlana; Boytsov, Sergey; Kontsevaya, Anna; Vigdorchik, Alexey; Guetz, Adam; Eriksson, Jennifer; Hughes, David

2014-01-01

Objectives Russia faces a high burden of cardiovascular disease. Prevalence of all cardiovascular risk factors, especially hypertension, is high. Elevated blood pressure is generally poorly controlled and medication usage is suboptimal. With a disease-model simulation, we forecast how various treatment programs aimed at increasing blood pressure control would affect cardiovascular outcomes. In addition, we investigated what additional benefit adding lipid control and smoking cessation to blood pressure control would generate in terms of reduced cardiovascular events. Finally, we estimated the direct health care costs saved by treating fewer cardiovascular events. Methods The Archimedes Model, a detailed computer model of human physiology, disease progression, and health care delivery was adapted to the Russian setting. Intervention scenarios of achieving systolic blood pressure control rates (defined as systolic blood pressure <140 mmHg) of 40% and 60% were simulated by modifying adherence rates of an antihypertensive medication combination and compared with current care (23.9% blood pressure control rate). Outcomes of major adverse cardiovascular events; cerebrovascular event (stroke), myocardial infarction, and cardiovascular death over a 10-year time horizon were reported. Direct health care costs of strokes and myocardial infarctions were derived from official Russian statistics and tariff lists. Results To achieve systolic blood pressure control rates of 40% and 60%, adherence rates to the antihypertensive treatment program were 29.4% and 65.9%. Cardiovascular death relative risk reductions were 13.2%, and 29.6%, respectively. For the current estimated 43,855,000-person Russian hypertensive population, each control-rate scenario resulted in an absolute reduction of 1.0 million and 2.4 million cardiovascular deaths, and a reduction of 1.2 million and 2.7 million stroke/myocardial infarction diagnoses, respectively. Averted direct costs from current care levels ($7.6 billion [in United States dollars]) were $1.1 billion and $2.6 billion, respectively. PMID:25141122

Adverse Heart-Lung Interactions in Ventilator-induced Lung Injury.

PubMed

Katira, Bhushan H; Giesinger, Regan E; Engelberts, Doreen; Zabini, Diana; Kornecki, Alik; Otulakowski, Gail; Yoshida, Takeshi; Kuebler, Wolfgang M; McNamara, Patrick J; Connelly, Kim A; Kavanagh, Brian P

2017-12-01

In the original 1974 in vivo study of ventilator-induced lung injury, Webb and Tierney reported that high Vt with zero positive end-expiratory pressure caused overwhelming lung injury, subsequently shown by others to be due to lung shear stress. To reproduce the lung injury and edema examined in the Webb and Tierney study and to investigate the underlying mechanism thereof. Sprague-Dawley rats weighing approximately 400 g received mechanical ventilation for 60 minutes according to the protocol of Webb and Tierney (airway pressures of 14/0, 30/0, 45/10, 45/0 cm H 2 O). Additional series of experiments (20 min in duration to ensure all animals survived) were studied to assess permeability (n = 4 per group), echocardiography (n = 4 per group), and right and left ventricular pressure (n = 5 and n = 4 per group, respectively). The original Webb and Tierney results were replicated in terms of lung/body weight ratio (45/0 > 45/10 ≈ 30/0 ≈ 14/0; P < 0.05) and histology. In 45/0, pulmonary edema was overt and rapid, with survival less than 30 minutes. In 45/0 (but not 45/10), there was an increase in microvascular permeability, cyclical abolition of preload, and progressive dilation of the right ventricle. Although left ventricular end-diastolic pressure decreased in 45/10, it increased in 45/0. In a classic model of ventilator-induced lung injury, high peak pressure (and zero positive end-expiratory pressure) causes respiratory swings (obliteration during inspiration) in right ventricular filling and pulmonary perfusion, ultimately resulting in right ventricular failure and dilation. Pulmonary edema was due to increased permeability, which was augmented by a modest (approximately 40%) increase in hydrostatic pressure. The lung injury and acute cor pulmonale is likely due to pulmonary microvascular injury, the mechanism of which is uncertain, but which may be due to cyclic interruption and exaggeration of pulmonary blood flow.

Ling classification describes endoscopic progressive process of achalasia and successful peroral endoscopy myotomy prevents endoscopic progression of achalasia.

PubMed

Zhang, Wen-Gang; Linghu, En-Qiang; Chai, Ning-Li; Li, Hui-Kai

2017-05-14

To verify the hypothesis that the Ling classification describes the endoscopic progressive process of achalasia and determine the ability of successful peroral endoscopic myotomy (POEM) to prevent endoscopic progression of achalasia. We retrospectively reviewed the endoscopic findings, symptom duration, and manometric data in patients with achalasia. A total of 359 patients (197 women, 162 men) with a mean age of 42.1 years (range, 12-75 years) were evaluated. Symptom duration ranged from 2 to 360 mo, with a median of 36 mo. Patients were classified with Ling type I ( n = 119), IIa ( n = 106), IIb ( n = 60), IIc ( n = 60), or III ( n = 14), according to the Ling classification. Of the 359 patients, 349 underwent POEM, among whom 21 had an endoscopic follow-up for more than 2 years. Pre-treatment and post-treatment Ling classifications of these 21 patients were compared. Symptom duration increased significantly with increasing Ling classification (from I to III) ( P < 0.05), whereas lower esophageal sphincter pressure decreased with increasing Ling type (from I to III) ( P < 0.05). There was no difference in sex ratio or onset age among the Ling types, although the age at time of diagnosis was higher in Ling types IIc and III than in Ling types I, IIa, and IIb. Of the 21 patients, 19 underwent high-resolution manometry both before and after treatment. The mean preoperative and postoperative lower esophageal sphincter pressure were 34.6 mmHg (range, 15.3-59.4 mmHg) and 15.0 mmHg (range, 2.1-21.6 mmHg), respectively, indicating a statistically significant decrease after POEM. All of the 21 patients were treated successfully by POEM (postoperative Eckardt score ≤ 3) and still had the same Ling type during a mean follow-up period of 37.8 mo (range, 24-51 mo). The Ling classification represents the endoscopic progressive process of achalasia and may be able to serve as an endoscopic assessment criterion for achalasia. Successful POEM (Eckardt score ≤ 3) seems to have the ability to prevent endoscopic evolvement of achalasia. However, studies with larger populations are warranted to confirm our findings.

Serum Carotenoids Reduce Progression of Early Atherosclerosis in the Carotid Artery Wall among Eastern Finnish Men

PubMed Central

Karppi, Jouni; Kurl, Sudhir; Ronkainen, Kimmo; Kauhanen, Jussi; Laukkanen, Jari A.

2013-01-01

Background Several previous epidemiologic studies have shown that high blood levels of carotenoids may be protective against early atherosclerosis, but results have been inconsistent. We assessed the association between atherosclerotic progression, measured by intima-media thickness of the common carotid artery wall, and serum levels of carotenoids. Methods We studied the effect of carotenoids on progression of early atherosclerosis in a population-based study. The association between concentrations of serum carotenoids, and intima-media thickness of the common carotid artery wall was explored in 840 middle-aged men (aged 46–65 years) from Eastern Finland. Ultrasonography of the common carotid arteries were performed at baseline and 7-year follow-up. Serum levels of carotenoids were analyzed at baseline. Changes in mean and maximum intima media thickness of carotid artery wall were related to baseline serum carotenoid levels in covariance analyses adjusted for covariates. Results In a covariance analysis with adjustment for age, ultrasound sonographer, maximum intima media thickness, examination year, body mass index, systolic blood pressure, smoking, physical activity, serum LDL cholesterol, family history of coronary heart disease, antihypertensive medication and serum high sensitivity C-reactive protein, 7-year change in maximum intima media thickness was inversely associated with lycopene (p = 0.005), α-carotene (p = 0.002) and β-carotene (p = 0.019), respectively. Conclusions The present study shows that high serum concentrations of carotenoids may be protective against early atherosclerosis. PMID:23700460

Primary obstructive megaureter: the role of high pressure balloon dilation.

PubMed

Romero, Rosa M; Angulo, Jose Maria; Parente, Alberto; Rivas, Susana; Tardáguila, Ana Rosa

2014-05-01

There is a growing interest in minimally invasive treatment of primary obstructive megaureter (POM) in children. The absence of long-term follow-up data, however, makes it difficult to establish the indication for an endoscopic approach. The aim of our study is to determine the long-term efficacy of endourologic high-pressure balloon dilation of the vesicoureteral junction (VUJ) in children with POM that necessitates surgical treatment. We retrospectively reviewed the clinical records from children with POM who were treated with endourologic high-pressure balloon dilation of the VUJ from March 2003 to April 2010. To determine the long-term, a cohort study was conducted in November 2011. Endourologic dilation of the VUJ was performed with a semicompliant high-pressure balloon (2.7 FG) with a minimum balloon size of 3 mm, followed by placement of a Double-J stent. We have treated 29 (32 renal units, left [n=16], right [n=10] and bilateral [n=3]) children with a diagnosis of POM within this period. The median age at the time of the endourologic treatment was 4.04 months (range 1.6-39 months). In three cases, an open ureteral reimplantation was needed, in two cases because of intraoperative technical failure and postoperative Double-J stent migration in one patient. The 26 children (29 renal units) who had a successful endourologic dilation of the VUJ were followed with ultrasonography and MAG-3-Lasix (furosemide) studies that showed a progressive improvement of both the ureterohydronephrosis and drainage in the first 18 months in 20 patients (23 renal units) (69%). In two patients who were treated with a 3 mm balloon, a further dilation was needed, with an excellent outcome. The cohort study (at a median follow-up of 47 months) showed that in all patients who had a good outcome at the 18-month follow-up after endourologic balloon dilation remained asymptomatic with resolution of ureterohydronephrosis on the US and good drainage on the renogram, in the children with some persistent hydronephrosis. Our study shows that children with POM who were treated with high-pressure ballon dilation of the VUJ who have satisfactory appearance at 18 months maintain these results over time.

Molybdenum-copper and tungsten-copper alloys and method of making

DOEpatents

Schmidt, Frederick A.; Verhoeven, John D.; Gibson, Edwin D.

1989-05-23

Molybdenum-copper and tungsten-copper alloys are prepared by a consumable electrode method in which the electrode consists of a copper matrix with embedded strips of refractory molybdenum or tungsten. The electrode is progressively melted at its lower end with a superatmospheric inert gas pressure maintained around the liquifying electrode. The inert gas pressure is sufficiently above the vapor pressure of copper at the liquidus temperature of the alloy being formed to suppress boiling of liquid copper.

Non operative management of cerebral abscess

NASA Astrophysics Data System (ADS)

Batubara, C. A.

2018-03-01

Cerebral abscess is a focal intracerebral infection that begins as a localized area of cerebritis and develops into a collection of pus surrounded by a well-vascularized capsule. Patients typically present with varying combinations of aheadache, progressive neurologic deficits, seizures, and evidence of infection. Computed Tomography and Magnetic Resonance Imagingare the most important diagnostic tools in diagnosing cerebral abscess. The treatment of cerebral abscess has been a challenge. Small cerebralabscesses (< 2.5 cm) have been treated empirically with antibiotics. Elevation of intracranial pressure and threatening herniation can be managed by the use of intravenous mannitol (or hypertonic saline) and dexamethasone. Acute seizures should be terminated with the administration of intravenous benzodiazepines or by intravenous fosphenytoin. Anticonvulsants prophylaxis must be initiated immediately and continued at least one year due to high risk in the cerebral abscesses. Easier detection of underlying conditions, monitoring of the therapeutic progress, and recognition of complications have probably contributed to the improved prognosis.

Commentary: Using Impedance Cardiography to Detect Asymptomatic Cardiovascular Disease in Prehypertensive Adults with Risk Factors.

PubMed

DeMarzo, Arthur P

2018-06-01

New guidelines on hypertension eliminated the classification of prehypertension and divided those blood pressure (BP) levels into elevated BP and stage 1 hypertension. For elevated BP, this study showed that cardiovascular (CV) abnormalities were prevalent in adults over 40 years of age with at least 2 CV risk factors. Detecting abnormalities of the CV system moves a patient from being at high risk to having earlystage cardiovascular disease (CVD) and supports a decision to treat. By redefining stage 1 and lowering the target BP, the new guidelines have set an ambitious goal for early intervention to prevent progression of CVD. Proper drug selection and titration are critical. Hypertensive patients have diverse CV abnormalities that can be quantified by impedance cardiography. By stratifying patients with ventricular, vascular, and hemodynamic abnormalities, treatment can be customized based on the abnormal underlying mechanisms to rapidly control BP and prevent progression of CVD.

Physiological and behavioural responses associated with feather removal in Gallus gallus var domesticus.

PubMed

Gentle, M J; Hunter, L N

1991-01-01

Electroencephalographic, cardiovascular and behavioural parameters were examined in Gallus gallus var domesticus in response to feather removal. The progressive removal of feathers resulted in marked changes in the bird's behaviour from an alert agitated response following the initial removals to periods of crouching immobility following successive removals. During the periods of immobility the birds showed a high amplitude low frequency EEG pattern and successive removals resulted in a progressive increase in the total duration of this activity in the two minutes after removal. The heart rate response to feather removal was variable whereas the blood pressure always increased and this increase was followed by a gradual return to pre-stimulus levels. There were no consistent cardiovascular responses related to the immobility. It was concluded that feather removal is likely to be painful to the bird and feather removal by flockmates can be categorised as a welfare problem.

Current Development in Treatment and Hydrogen Energy Conversion of Organic Solid Waste

NASA Astrophysics Data System (ADS)

Shin, Hang-Sik

2008-02-01

This manuscript summarized current developments on continuous hydrogen production technologies researched in Korea advanced institute of science and technology (KAIST). Long-term continuous pilot-scale operation of hydrogen producing processes fed with non-sterile food waste exhibited successful results. Experimental findings obtained by the optimization processes of growth environments for hydrogen producing bacteria, the development of high-rate hydrogen producing strategies, and the feasibility tests for real field application could contribute to the progress of fermentative hydrogen production technologies. Three major technologies such as controlling dilution rate depending on the progress of acidogenesis, maintaining solid retention time independently from hydraulic retention time, and decreasing hydrogen partial pressure by carbon dioxide sparging could enhance hydrogen production using anaerobic leaching beds reactors and anaerobic sequencing batch reactors. These findings could contribute to stable, reliable and effective performances of pilot-scale reactors treating organic wastes.

TOPICAL REVIEW: A review of micropumps

NASA Astrophysics Data System (ADS)

Laser, D. J.; Santiago, J. G.

2004-06-01

We survey progress over the past 25 years in the development of microscale devices for pumping fluids. We attempt to provide both a reference for micropump researchers and a resource for those outside the field who wish to identify the best micropump for a particular application. Reciprocating displacement micropumps have been the subject of extensive research in both academia and the private sector and have been produced with a wide range of actuators, valve configurations and materials. Aperiodic displacement micropumps based on mechanisms such as localized phase change have been shown to be suitable for specialized applications. Electroosmotic micropumps exhibit favorable scaling and are promising for a variety of applications requiring high flow rates and pressures. Dynamic micropumps based on electrohydrodynamic and magnetohydrodynamic effects have also been developed. Much progress has been made, but with micropumps suitable for important applications still not available, this remains a fertile area for future research.

Progressing batch hydrolysis process

DOEpatents

Wright, J.D.

1985-01-10

A progressive batch hydrolysis process is disclosed for producing sugar from a lignocellulosic feedstock. It comprises passing a stream of dilute acid serially through a plurality of percolation hydrolysis reactors charged with feed stock, at a flow rate, temperature and pressure sufficient to substantially convert all the cellulose component of the feed stock to glucose. The cooled dilute acid stream containing glucose, after exiting the last percolation hydrolysis reactor, serially fed through a plurality of pre-hydrolysis percolation reactors, charged with said feedstock, at a flow rate, temperature and pressure sufficient to substantially convert all the hemicellulose component of said feedstock to glucose. The dilute acid stream containing glucose is cooled after it exits the last prehydrolysis reactor.

Progressing batch hydrolysis process

DOEpatents

Wright, John D.

1986-01-01

A progressive batch hydrolysis process for producing sugar from a lignocellulosic feedstock, comprising passing a stream of dilute acid serially through a plurality of percolation hydrolysis reactors charged with said feedstock, at a flow rate, temperature and pressure sufficient to substantially convert all the cellulose component of the feedstock to glucose; cooling said dilute acid stream containing glucose, after exiting the last percolation hydrolysis reactor, then feeding said dilute acid stream serially through a plurality of prehydrolysis percolation reactors, charged with said feedstock, at a flow rate, temperature and pressure sufficient to substantially convert all the hemicellulose component of said feedstock to glucose; and cooling the dilute acid stream containing glucose after it exits the last prehydrolysis reactor.

Neurologic decompression sickness following cabin pressure fluctuations at high altitude.

PubMed

Auten, Jonathan D; Kuhne, Michael A; Walker, Harlan M; Porter, Henry O

2010-04-01

Decompression sickness (DCS) occurs in diving, altitude chamber exposures, and unpressurized or depressurized high-altitude flights. Because DCS takes many forms, in-flight cases may be misinterpreted as hypoxia, hyperventilation, or viral illness, with resulting failure to respond appropriately. In this case, a 28-yr-old male pilot of a single-seat, tactical aircraft experienced 12 rapid pressure fluctuations while flying at 43,000 ft above sea level. He had no symptoms and decided to complete the flight, which required an additional 2 h in the air. Approximately 1 h later he began to experience fatigue, lightheadedness, and confusion, which he interpreted as onset of a viral illness. However, symptoms progressed to visual, cognitive, motor, and sensory degradations and it was with some difficulty that he landed safely at his destination. Neurologic DCS was suspected on initial evaluation by flight line medical personnel because of the delayed onset and symptom progression. He was transferred to a local Emergency Department and noted to have altered mental status, asymmetric motor deficits, and non-dermatomal paresthesias of the upper and lower extremities. Approximately 3.5 h after the incident and 2.5 h after the onset of symptoms he began hyperbaric oxygen therapy. He received partial relief at 30 min of the Navy DiveTable 6 and full resolution at 90 min; there were no recurrent symptoms at a 1-yr follow-up. This case highlights the importance of early recognition of in-flight DCS symptoms and landing as soon as possible rather than as soon as practical in all likely scenarios.

Study on the new technology of removing gangue and retaining roadway in complicated roof condition

NASA Astrophysics Data System (ADS)

Chen, Yanhao; Jiang, Cong

2018-04-01

This article in view of the complex roof conditions was carried on study about the new technology of removing gangue and retaining roadway, and tells a method of progressive reinforced concrete wall segment with gangue to keep the roadway, the roadway beside the support system is mainly composed of the lining, waste rock wall and the outer wall, the wall and the outer wall of concrete material width to build the strength of the progressive type filling body, waste rock wall with woven bag with waste rock assembled, paragraphs geological survey on the actual distance should be based on working face. This method relies on the interior of the gangue wall to make the pressure control and allow the roof to sink. In this paper, the finite deformation control of the roof is realized by the gangue wall and the high strength filling body. This method has the characteristics of low entry cost, good forming of roadway, high security and good stability, and can be applied to complex geological conditions such as hard roof.

Challenges for the prevention of primary and secondary stroke: the importance of lowering blood pressure and total cardiovascular risk.

PubMed

Chalmers, J; Chapman, N

2001-01-01

It is well established that blood pressure lowering is effective for the primary prevention of stroke and other cardiovascular disorders in subjects with blood pressures as low as 140/90 mmHg, and up to 80 years of age. Despite this knowledge, blood pressure levels are controlled in less than 25% of the hypertensive population worldwide. It has taken longer to prove that blood pressure lowering is equally effective for the prevention of recurrent stroke. The results of PROGRESS (Perindopril Protection Against Recurrent Stroke Study) have confirmed that a perindopril-based regimen in subjects with cerebrovascular disease substantially reduces the incidence of secondary stroke and primary myocardial infarction. It is daunting to recall that it has taken almost two decades for beta-blockers to be widely used for the secondary prevention of myocardial infarction, since widespread use of the PROGRESS regimen would prevent more than half a million strokes worldwide each year. The real challenge now is to implement novel and effective strategies for the control of blood pressure and other cardiovascular risk factors worldwide. Strategies should include lifestyle measures, such as stopping smoking, exercise and reducing overweight. There is a real need to identify hypertensive subjects and treat them with blood pressure lowering drugs for primary prevention. In subjects with established cardiovascular disease, consideration should be given to a range of proven interventions for secondary prevention, such as blood pressure lowering, irrespective of current blood pressure, anti-platelet drugs, statins for lowering cholesterol and glycaemic control in diabetics. Among new strategies to lower overall cardiovascular risk, consideration should be given to the development of single-pill combinations of drugs of known efficacy, including various combinations of ACE inhibitors, diuretics, beta-blockers, aspirin and statins, among others.

Use of Modal Acoustic Emission to Monitor Damage Progression in Carbon Fiber/Epoxy and Implications for Composite Structures

NASA Technical Reports Server (NTRS)

Waller, J. M.; Nichols, C. T.; Wentzel, D. J.; Saulsberry R. L.

2010-01-01

Broad-band modal acoustic emission (AE) data was used to characterize micromechanical damage progression in uniaxial IM7 and T1000 carbon fiber-epoxy tows and an IM7 composite overwrapped pressure vessel (COPV) subjected to an intermittent load hold tensile stress profile known to activate the Felicity ratio (FR). Damage progression was followed by inspecting the Fast Fourier Transforms (FFTs) associated with acoustic emission events. FFT analysis revealed the occurrence of cooperative micromechanical damage events in a frequency range between 100 kHz and 1 MHz. Evidence was found for the existence of a universal damage parameter, referred to here as the critical Felicity ratio, or Felicity ratio at rupture (FR*), which had a value close to 0.96 for the tows and the COPV tested. The implications of using FR* to predict failure in carbon/epoxy composite materials and related composite components such as COPVs are discussed. Trends in the FFT data are also discussed; namely, the difference between the low and high energy events, the difference between early and late-life events, comparison of IM7 and T1000 damage progression, and lastly, the similarity of events occurring at the onset of significant acoustic emission used to calculate the FR.

Deuterium isotope effects in polymerization of benzene under pressure

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

Cai, Weizhao; Dunuwille, Mihindra; He, Jiangang

The enormous versatility in the properties of carbon materials depends on the content of the sp 2 and sp 3 covalent bonds. Under compression, if intermolecular distances cross a critical threshold, then unsaturated hydrocarbons gradually transform to saturated carbon polymers. However, the mechanism of polymerization, even for benzene, the simplest aromatic hydrocarbon, is still not understood. We used high-pressure synchrotron X-ray, neutron diffraction, and micro-Raman spectroscopy together with density functional calculations to investigate the isotope effects in benzene isotopologues C 6H 6 and C 6D 6 up to 46.0 GPa. Raman spectra of polymeric products recovered from comparable pressures showmore » the progression of polymerization exhibiting a pronounced kinetic isotope effect. Kinetically retarded reactions in C 6D 6 shed light on the mechanism of polymerization of benzene. Lastly, we find that C 6D 6-derived products recovered from P < 35 GPa actively react with moisture, forming polymers with higher sp 3 hydrogen contents. Significant isotopic shift (≥7 GPa) in persistence of Bragg reflections of C 6D 6 is observed.« less

Early aggressive intraocular pressure lowering, target intraocular pressure, and a novel concept for glaucoma care.

PubMed

Singh, Kuldev; Shrivastava, Anurag

2008-11-01

Early diagnosis of glaucomatous optic nerve damage offers the potential for early treatment which may prevent vision loss from this neurodegenerative disease. Even in patients who do not begin early treatment, early diagnosis allows for better monitoring of disease at a stage where the stakes are lower relative to later stages of the disease. For these reasons, early diagnosis of glaucomatous optic nerve disease is desirable and opens the door for appropriately aggressive therapy. The target intraocular pressure (IOP) concept is widely employed by glaucoma practitioners. Although there have been no randomized clinical trials or other high-quality studies showing the benefits of setting a target IOP versus not using this approach, there is ample evidence that lowering IOP slows glaucoma progression and, in general, lower is better, regardless of disease stage and baseline IOP level. We propose an alternative approach to managing glaucoma without the use of the target IOP concept and suggest that this market IOP concept should be compared with the target IOP approach in an appropriately powered comparative clinical trial.

Deuterium isotope effects in polymerization of benzene under pressure

DOE PAGES

Cai, Weizhao; Dunuwille, Mihindra; He, Jiangang; ...

2017-04-10

The enormous versatility in the properties of carbon materials depends on the content of the sp 2 and sp 3 covalent bonds. Under compression, if intermolecular distances cross a critical threshold, then unsaturated hydrocarbons gradually transform to saturated carbon polymers. However, the mechanism of polymerization, even for benzene, the simplest aromatic hydrocarbon, is still not understood. We used high-pressure synchrotron X-ray, neutron diffraction, and micro-Raman spectroscopy together with density functional calculations to investigate the isotope effects in benzene isotopologues C 6H 6 and C 6D 6 up to 46.0 GPa. Raman spectra of polymeric products recovered from comparable pressures showmore » the progression of polymerization exhibiting a pronounced kinetic isotope effect. Kinetically retarded reactions in C 6D 6 shed light on the mechanism of polymerization of benzene. Lastly, we find that C 6D 6-derived products recovered from P < 35 GPa actively react with moisture, forming polymers with higher sp 3 hydrogen contents. Significant isotopic shift (≥7 GPa) in persistence of Bragg reflections of C 6D 6 is observed.« less

Downhole measurements and fluid chemistry of a castle rock steam well, the Geysers, Lake County, California

USGS Publications Warehouse

Truesdell, A.H.; Nathenson, M.; Frye, G.A.

1981-01-01

Wellbore and reservoir processes in a steam well in the Castle Rock field of The Geysers have been studied by means of down-hole pressure and temperature measurements and analyses of ejected water and steam produced under bleed and full flow. Down-hole measurements show that below a vapor zone there is liquid water in the well in pressure equilibrium with reservoir steam at a depth of 2290 m. The progressive decreases, from 1973 to 1977, of pressure and temperature in the vapor zone indicate that wellbore heat loss is high enough to condense a large fraction of the steam inflow. The chemical composition of water ejected from the well is consistent with an origin from wellbore condensation of steam. Calculations using the differences in gas and isotopic compositions between bleed and full-flow steam show that about half of the full-flow steam originated as liquid water in the reservoir and that about 30% of the steam entering the well under bleed was condensed in the wellbore and drained downward. Heat loss calculations are also consistent with this amount of condensation. ?? 1981.

Feasibility of nitric oxide administration by neonatal helmet-CPAP: a bench study.

PubMed

Trevisanuto, Daniele; Doglioni, Nicoletta; Micaglio, Massimo; Zanardo, Vincenzo

2007-09-01

Inhaled nitric oxide (NO) may have a role in the treatment of preterm infants with respiratory failure. We evaluated the feasibility of administering NO therapy by a new continuous positive airway pressure (CPAP) system (neonatal helmet-CPAP). While maintaining a constant total flow of 8, 10, and 12 l.min(-1), NO concentrations were progressively increased to 5, 10, 20, and 40 p.p.m. in the neonatal helmet-CPAP pressure chamber (5 cmH2O). NO, NO2, and O2 concentrations were measured in the pressure chamber and the immediate external environment. In the chamber, NO2 levels remained low (

Cold atmospheric pressure plasma jets: Interaction with plasmid DNA and tailored electron heating using dual-frequency excitation

NASA Astrophysics Data System (ADS)

Niemi, K.; O'Neill, C.; Cox, L. J.; Waskoenig, J.; Hyland, W. B.; McMahon, S. J.; Reuter, S.; Currell, F. J.; Graham, W. G.; O'Connell, D.; Gans, T.

2012-05-01

Recent progress in plasma science and technology has enabled the development of a new generation of stable cold non-equilibrium plasmas operating at ambient atmospheric pressure. This opens horizons for new plasma technologies, in particular in the emerging field of plasma medicine. These non-equilibrium plasmas are very efficient sources for energy transport through reactive neutral particles (radicals and metastables), charged particles (ions and electrons), UV radiation, and electro-magnetic fields. The effect of a cold radio frequency-driven atmospheric pressure plasma jet on plasmid DNA has been investigated. The formation of double strand breaks correlates well with the atomic oxygen density. Taken with other measurements, this indicates that neutral components in the jet are effective in inducing double strand breaks. Plasma manipulation techniques for controlled energy delivery are highly desirable. Numerical simulations are employed for detailed investigations of the electron dynamics, which determines the generation of reactive species. New concepts based on nonlinear power dissipation promise superior strategies to control energy transport for tailored technological exploitations.

Boundary identification and error analysis of shocked material images

NASA Astrophysics Data System (ADS)

Hock, Margaret; Howard, Marylesa; Cooper, Leora; Meehan, Bernard; Nelson, Keith

2017-06-01

To compute quantities such as pressure and velocity from laser-induced shock waves propagating through materials, high-speed images are captured and analyzed. Shock images typically display high noise and spatially-varying intensities, causing conventional analysis techniques to have difficulty identifying boundaries in the images without making significant assumptions about the data. We present a novel machine learning algorithm that efficiently segments, or partitions, images with high noise and spatially-varying intensities, and provides error maps that describe a level of uncertainty in the partitioning. The user trains the algorithm by providing locations of known materials within the image but no assumptions are made on the geometries in the image. The error maps are used to provide lower and upper bounds on quantities of interest, such as velocity and pressure, once boundaries have been identified and propagated through equations of state. This algorithm will be demonstrated on images of shock waves with noise and aberrations to quantify properties of the wave as it progresses. DOE/NV/25946-3126 This work was done by National Security Technologies, LLC, under Contract No. DE- AC52-06NA25946 with the U.S. Department of Energy and supported by the SDRD Program.

Extended Solids of Carbon Monoxide formed from Re2(CO)12

NASA Astrophysics Data System (ADS)

Ciezak-Jenkins, Jennifer

Extended solids are formed from simple molecular gases under extreme P/T and are of considerable interest as high-energy-density materials. It has been postulated that a transformation from a single-bonded polymeric-like material back to the more stable triply-bonded diatomic phase would be a highly exothermic process yielding large amounts of energy. The extended polymeric solid of CO was first reported and recovered from high pressure conditions in 2005. Although the material was found to have potentially interesting energetic properties, it showed a number of stability issues, degrading into CO2 and graphitic carbon over 3 to 5 days. As such, our lab has been focused on the identification of methods to increase the metastability of the recovered solid. Metal carbonyls offer one such route for stabilization. In this talk, our progress in the study of the synthesis, characterization, and recovery of extended solids of CO starting from Re2(CO)12\\ to pressures near 50 GPa will be presented. I will discuss the analysis and the implications of these results. New opportunities and challenges that have arisen in the course of our studies that will be pursued in the future will also be presented. Ref

Fast log P determination by ultra-high-pressure liquid chromatography coupled with UV and mass spectrometry detections.

PubMed

Henchoz, Yveline; Guillarme, Davy; Martel, Sophie; Rudaz, Serge; Veuthey, Jean-Luc; Carrupt, Pierre-Alain

2009-08-01

Ultra-high-pressure liquid chromatography (UHPLC) systems able to work with columns packed with sub-2 microm particles offer very fast methods to determine the lipophilicity of new chemical entities. The careful development of the most suitable experimental conditions presented here will help medicinal chemists for high-throughput screening (HTS) log P(oct) measurements. The approach was optimized using a well-balanced set of 38 model compounds and a series of 28 basic compounds such as beta-blockers, local anesthetics, piperazines, clonidine, and derivatives. Different organic modifiers and hybrid stationary phases packed with 1.7-microm particles were evaluated in isocratic as well as gradient modes, and the advantages and limitations of tested conditions pointed out. The UHPLC approach offered a significant enhancement over the classical HPLC methods, by a factor 50 in the lipophilicity determination throughput. The hyphenation of UHPLC with MS detection allowed a further increase in the throughput. Data and results reported herein prove that the UHPLC-MS method can represent a progress in the HTS-measurement of lipophilicity due to its speed (at least a factor of 500 with respect to HPLC approaches) and to an extended field of application.

Five-Year Incidence of Primary Open-Angle Glaucoma and Rate of Progression in Health Center-Based Korean Population: The Gangnam Eye Study

PubMed Central

Jeoung, Jin Wook; Park, Ki Ho; Kim, Dong Myung

2014-01-01

Objective To investigate the 5-year incidence and progression rate of primary open-angle glaucoma (POAG) in a health-center-based Korean population. Methods The study population comprised 5,021 subjects who participated in standardized health screening (including non-contact tonometry and fundus photography) at the Gangnam Healthcare Center during the period from January 2005 to December 2006 and again from January 2010 to December 2011. Among these subjects, 948 (18.9%) with findings suggestive of glaucoma were subjected to a comprehensive glaucoma evaluation, which included applanation tonometry and standard automated perimetry. Based on the results, the subjects were diagnosed as POAG suspect or definite POAG. Results The 5-year incidences of POAG suspect and definite POAG were 0.84% (42 subjects) and 0.72% (36 subjects), respectively. The rate of progression from POAG suspect to definite POAG was 4.75% per year. In subjects with a baseline intraocular pressure (IOP) >21 mmHg, the incidence of POAG suspect or definite POAG was significantly higher than in those with a baseline IOP≤21 mmHg (32% vs. 1.05%; P<0.001). A multivariate analysis showed that the progression from POAG suspect to definite POAG was significantly associated with older age (odds ratio [OR], 1.07; 95% confidence interval [CI], 1.03–1.10), higher baseline IOP (OR, 1.10; 95% CI, 1.01–1.24), higher body mass index (BMI) (OR, 1.15; 95% CI, 1.03–1.31), higher education level (OR, 1.57; 95% CI, 1.05–2.17), and higher hematocrit level (OR, 1.22; 95% CI, 1.08–1.43). Conclusions In the health-center-based Korean population, the 5-year incidence of POAG was 0.72%, and the rate of progression from POAG suspect to definite POAG was 4.75% per year. This study identified old age, high baseline IOP, high BMI, high level of education, and high hematocrit level as significant risk factors for incident POAG. PMID:25474589

Preliminary effects of progressive muscle relaxation on cigarette craving and withdrawal symptoms in experienced smokers in acute cigarette abstinence: a randomized controlled trial.

PubMed

Limsanon, Thatsanee; Kalayasiri, Rasmon

2015-03-01

Cigarette craving usually occurs in conjunction with unpleasant feelings, including stress, as part of a withdrawal syndrome. Progressive muscle relaxation (PMR), a behavioral technique used to reduce stress by concentrating on achieving muscle relaxation, may reduce levels of cigarette craving and other substance-related negative feelings and withdrawal symptoms. Demographic and cigarette use data were collected from 32 experienced smokers at the King Chulalongkorn Memorial Hospital, Bangkok, Thailand using the Semi-Structured Assessment for Drug Dependence and Alcoholism. Participants were asked to refrain from smoking for at least 3 hours before the visit (acute abstinence) and were randomly allocated to a 1-session PMR group (n =16) or a control activity group (e.g., reading newspaper, n =16). The intervention group was instructed to practice PMR individually in a quiet, private, air-conditioned room for about 20minutes. Craving, other substance-related feelings, and autonomic nervous responses (e.g., blood pressure and pulse rate) were assessed immediately before and after the 1-session intervention. There were no differences in demographics, cigarette use/dependence, and baseline craving characteristics between the PMR and control groups. However, the control group had higher levels of high and paranoia feeling, and pulse rate than the PMR group at baseline. After practicing PMR, but not after a control activity, smokers undergoing acute abstinence had significantly lower levels of cigarette craving, withdrawal symptoms, and systolic blood pressure than at baseline. After controlling for baseline differences, abstaining smokers using PMR had lower levels of cigarette craving, withdrawal symptoms, and systolic blood pressure than smokers who undertook a control activity. PMR significantly reduces cigarette craving, withdrawal symptoms, and blood pressure in smokers undergoing acute abstinence. PMR may be used as an adjunct to cigarette dependency treatments. Copyright © 2014. Published by Elsevier Ltd.

Evaluation of distributed gas cooling of pressurized PAFC for utility power generation

NASA Technical Reports Server (NTRS)

Farooque, M.; Hooper, M.; Maru, H.

1981-01-01

A proof-of-concept test for a gas-cooled pressurized phosphoric acid fuel cell is described. After initial feasibility studies in short stacks, two 10 kW stacks are tested. Progress includes: (1) completion of design of the test stations with a recirculating gas cooling loop; (2) atmospheric testing of the baseline stack.

AGOR 28: SIO Shipyard Representative Bi-Weekly Progress Report

DTIC Science & Technology

2014-09-23

LOCATIONS ( PL 720644-01 NR Square D 9012GAW5 Pressure Switch )(R/ASR) 1258/0 AGOR27 A051 STD Report - VENDOR RECOMMENDED SPARES (VRS) LISTINGS...TECHNICAL MANUALS AND SUPPLEMENTAL DATA ( #498 DI-055 (TM) for 532b Square D 9012GAW5 Pressure Switch )(R/ASR) 997/0 AGOR27 A055 TM Report - COMMERCIAL

Adequate (Or Adipose?) Yearly Progress: Assessing the Effect of "No Child Left Behind" on Children's Obesity

ERIC Educational Resources Information Center

Anderson, Patricia M.; Butcher, Kristin F.; Schanzenbach, Diane Whitmore

2017-01-01

This paper investigates how accountability pressures under No Child Left Behind (NCLB) may have affected students' rate of overweight. Schools facing pressure to improve academic outcomes may reallocate their efforts in ways that have unintended consequences for children's health. To examine the impact of school accountability, we create a unique…

The impact of different footwear characteristics, of a ballet flat pump, on centre of pressure progression and perceived comfort.

PubMed

Branthwaite, Helen; Chockalingam, Nachiappan; Greenhalgh, Andrew; Chatzistergos, Panagiotis

2014-09-01

Uncomfortable shoes have been attributed to poor fit and the cause of foot pathologies. Assessing and evaluating comfort and fit have proven challenging due to the subjective nature. The aim of this paper is to investigate the relationship between footwear characteristics and perceived comfort. Twenty-seven females assessed three different styles of ballet pump shoe for comfort using a comfort scale whilst walking along a 20 m walkway. The physical characteristics of the shoes and the progression of centre of pressure during walking were assessed. There were significant physical differences between each style, square shoe being the shortest, widest and stiffest and round shoe having the least volume at the toe box. Centre of pressure progression angle was centralised to the longitudinal axis of the foot when wearing each of the three shoes compared to barefoot. Length, width and cantilever bending stiffness had no impact on perceived comfort. Wearing snug fitting flexible soled round ballet flat pump is perceived to be the most comfortable of the shoe shapes tested producing a faster more efficient gait. Further investigations are required to assess impact/fit and upper material on perceived comfort to aid consumers with painful feet in purchasing shoes. Copyright © 2014 Elsevier Ltd. All rights reserved.

Hydromechanical Rock Mass Fatigue in Deep-Seated Landslides Accompanying Seasonal Variations in Pore Pressures

NASA Astrophysics Data System (ADS)

Preisig, Giona; Eberhardt, Erik; Smithyman, Megan; Preh, Alexander; Bonzanigo, Luca

2016-06-01

The episodic movement of deep-seated landslides is often governed by the presence of high pore pressures and reduced effective stresses along active shear surfaces. Pore pressures are subject to cyclic fluctuation under seasonal variations of groundwater recharge, resulting in an intermittent movement characterized by acceleration-deceleration phases. However, it is not always clear why certain acceleration phases reach alarming levels without a clear trigger (i.e., in the absence of an exceptional pore pressure event). This paper presents a conceptual framework linking hydromechanical cycling, progressive failure and fatigue to investigate and explain the episodic behavior of deep-seated landslides using the Campo Vallemaggia landslide in Switzerland as a case study. A combination of monitoring data and advanced numerical modeling is used. The principal processes forcing the slope into a critical disequilibrium state are analyzed as a function of rock mass damage and fatigue. Modeling results suggest that during periods of slope acceleration, the rock slope experiences localized fatigue and gradual weakening through slip along pre-existing natural fractures and yield of critically stressed intact rock bridges. At certain intervals, pockets of critically weakened rock may produce a period of enhanced slope movement in response to a small pore pressure increase similar to those routinely experienced each year. Accordingly, the distribution and connectivity of pre-existing permeable planes of weakness play a central role. These structures are often related to the rock mass's tectonic history or initiate (and dilate) in response to stress changes that disturb the entire slope, such as glacial unloading or seismic loading via large earthquakes. The latter is discussed in detail in a companion paper to this (Gischig et al., Rock Mech Rock Eng, 2015). The results and framework presented further demonstrate that episodic movement and progressive failure of deep-seated landslides cannot be analyzed by means of classical limit equilibrium tools but require advanced numerical models. When calibrated against slope monitoring data, the improved understanding of episodic slope movements can lead to more reliable early warning forecasting and improved landslide hazard management.

Functional assessment of the diaphragm by speckle tracking ultrasound during inspiratory loading.

PubMed

Oppersma, Eline; Hatam, Nima; Doorduin, Jonne; van der Hoeven, Johannes G; Marx, Gernot; Goetzenich, Andreas; Fritsch, Sebastian; Heunks, Leo M A; Bruells, Christian S

2017-11-01

Assessment of diaphragmatic effort is challenging, especially in critically ill patients in the phase of weaning. Fractional thickening during inspiration assessed by ultrasound has been used to estimate diaphragm effort. It is unknown whether more sophisticated ultrasound techniques such as speckle tracking are superior in the quantification of inspiratory effort. This study evaluates the validity of speckle tracking ultrasound to quantify diaphragm contractility. Thirteen healthy volunteers underwent a randomized stepwise threshold loading protocol of 0-50% of the maximal inspiratory pressure. Electric activity of the diaphragm and transdiaphragmatic pressures were recorded. Speckle tracking ultrasound was used to assess strain and strain rate as measures of diaphragm tissue deformation and deformation velocity, respectively. Fractional thickening was assessed by measurement of diaphragm thickness at end-inspiration and end-expiration. Strain and strain rate increased with progressive loading of the diaphragm. Both strain and strain rate were highly correlated to transdiaphragmatic pressure (strain r 2  = 0.72; strain rate r 2  = 0.80) and diaphragm electric activity (strain r 2  = 0.60; strain rate r 2  = 0.66). We conclude that speckle tracking ultrasound is superior to conventional ultrasound techniques to estimate diaphragm contractility under inspiratory threshold loading. NEW & NOTEWORTHY Transdiaphragmatic pressure using esophageal and gastric balloons is the gold standard to assess diaphragm effort. However, this technique is invasive and requires expertise, and the interpretation may be complex. We report that speckle tracking ultrasound can be used to detect stepwise increases in diaphragmatic effort. Strain and strain rate were highly correlated with transdiaphragmatic pressure, and therefore, diaphragm electric activity and speckle tracking might serve as reliable tools to quantify diaphragm effort in the future. Copyright © 2017 the American Physiological Society.

24-h pulse pressure cutoff point definition by office pulse pressure in a population of Spanish older hypertensive patients.

PubMed

Vinyoles, Ernest; de la Sierra, Alejandro; Roso-Llorach, Albert; Banegas, José R; de la Cruz, Juan José; Gorostidi, Manuel; Segura, Julián; Divisón, Juan Antonio; Ruíz-Hurtado, Gema; Ruilope, Luis Miguel

2017-05-01

The European Guidelines on Hypertension define an office pulse pressure (PP) at least 60 mmHg in the elderly patient as asymptomatic organ damage. Our objective was to estimate the cutoff point of 24-h PP that best predicts office PP associated with higher cardiovascular risk (≥60 mmHg) in hypertensive older patients. We studied all hypertensive patients at least 60 years with a first valid ambulatory blood pressure monitoring drawn from the Spanish ambulatory blood pressure monitoring registry. Receiver operating characteristic curves were used to estimate the best 24-h PP cutoff predictor of office PP at least 60 mmHg that maximized the sum of sensitivity and specificity. We included 52 246 hypertensive patients [52.4%, female; mean age (SD) 69.0 (7.0) years]. From these, 34 530 (66.1%) patients had an office PP at least 60 mmHg. The value of 24-h PP that best predicts higher risk clinic PP is 54.9 mmHg [sensitivity: 69.2%; specificity: 70.3%; area under the receiver operating characteristic curve of 0.761 (95% confidence interval 0.756-0.765)]. Mean clinic and 24-h PPs were progressively higher as the study participants were classified at higher cardiovascular risk group. Some 20.5% of patients presented isolated office high PP and 10% a masked high 24-h PP. In a large clinical sample of older hypertensive patients, the cutoff point of 24-h PP that best predicts office PP at least 60 mmHg is 55 mmHg. In 30.5% of cases, there is a discrepancy between office PP and ambulatory 24-h PP.

Magneto-hydrodynamic modeling of gas discharge switches

NASA Astrophysics Data System (ADS)

Doiphode, P.; Sakthivel, N.; Sarkar, P.; Chaturvedi, S.

2002-12-01

We have performed one-dimensional, time-dependent magneto-hydrodynamic modeling of fast gas-discharge switches. The model has been applied to both high- and low-pressure switches, involving a cylindrical argon-filled cavity. It is assumed that the discharge is initiated in a small channel near the axis of the cylinder. Joule heating in this channel rapidly raises its temperature and pressure. This drives a radial shock wave that heats and ionizes the surrounding low-temperature region, resulting in progressive expansion of the current channel. Our model is able to reproduce this expansion. However, significant difference of detail is observed, as compared with a simple model reported in the literature. In this paper, we present details of our simulations, a comparison with results from the simple model, and a physical interpretation for these differences. This is a first step towards development of a detailed 2-D model for such switches.

Progress in turbulence modeling for complex flow fields including effects of compressibility

NASA Technical Reports Server (NTRS)

Wilcox, D. C.; Rubesin, M. W.

1980-01-01

Two second-order-closure turbulence models were devised that are suitable for predicting properties of complex turbulent flow fields in both incompressible and compressible fluids. One model is of the "two-equation" variety in which closure is accomplished by introducing an eddy viscosity which depends on both a turbulent mixing energy and a dissipation rate per unit energy, that is, a specific dissipation rate. The other model is a "Reynolds stress equation" (RSE) formulation in which all components of the Reynolds stress tensor and turbulent heat-flux vector are computed directly and are scaled by the specific dissipation rate. Computations based on these models are compared with measurements for the following flow fields: (a) low speed, high Reynolds number channel flows with plane strain or uniform shear; (b) equilibrium turbulent boundary layers with and without pressure gradients or effects of compressibility; and (c) flow over a convex surface with and without a pressure gradient.

X-ray investigations related to the shock history of the Shergotty achondrite

NASA Technical Reports Server (NTRS)

Horz, F.; Hanss, R.; Serna, C.

1986-01-01

The shock stress suffered by naturally shocked materials from the Shergotty achondrite was studied using X-ray diffraction techniques and experimentally shocked augite and enstatite as standards. The Shergotty pyroxenes revealed the formation of continuous diffraction rings, line broadening, preferred orientation of small scale diffraction domains, and other evidence of substantial lattice disorders. As disclosed by the application of Debye-Scherrer techniques, they are hybrids between single crystals and fine-grained random powders. The pyroxene lattice is very resistant to shock damage on smaller scales. While measurable lattice disaggregation and progressive fragmentation occur below 25 GPa, little additional damage is suffered from application of pressures between 30 to 60 GPa, making pressure calibration of naturally shocked pyroxenes via X-ray methods difficult. Powder diffractometer scans on pure maskelynite fractions of Shergotty revealed small amounts of still coherently diffracting plagioclase, which may contribute to the high refractive indices of the diaplectic feldspar glasses of Shergotty.

Reaction Buildup of PBX Explosives JOB-9003 under Different Initiation Pressures

NASA Astrophysics Data System (ADS)

Zhang, Xu; Wang, Yan-fei; Hung, Wen-bin; Gu, Yan; Zhao, Feng; Wu, Qiang; Yu, Xin; Yu, Heng

2017-04-01

Aluminum-based embedded multiple electromagnetic particle velocity gauge technique has been developed in order to measure the shock initiation behavior of JOB-9003 explosives. In addition, another gauge element called a shock tracker has been used to monitor the progress of the shock front as a function of time, thus providing a position-time trajectory of the wave front as it moves through the explosive sample. The data are used to determine the position and time for shock to detonation transition. All the experimental results show that: the rising-up time of Al-based electromagnetic particle velocity gauge was very fast and less than 20 ns; the reaction buildup velocity profiles and the position-time for shock to detonation transition of HMX-based PBX explosive JOB-9003 with 1-8 mm depth from the origin of impact plane under different initiation pressures are obtained with high accuracy.

[Music and Glaucoma].

PubMed

Plange, N

2017-02-01

Music may have multiple influences on the human organism. A possible therapeutic effect for patients with glaucoma has been postulated, aside from the known impact of music on the cardiovascular system, psychogenic effects and a short-term improvement in mental performance (Mozart effect). The higher level of mental stress in patients with glaucoma and type-A personality behaviour may be related to higher intraocular pressure in patients with glaucoma. Relaxing music may have a positive impact in these patients, related to a reduction in intraocular pressure or its fluctuations. However, only limited data exist on the effects of music on intraocular pressure. No clinical studies have yet been performed to investigate the effect of music or music therapy on glaucoma progression. The music of Mozart may influence visual field examinations, possibly due to a positive short term effect on mental performance. This factor needs to be addressed in studies dealing with the effect of music in glaucoma. The relevance of intraocular pressure increases in professional wind instrument players is controversial. An increased level of care might be advisable in patients with advanced glaucoma. The influences of music on humans, altered personality profiles in patients with glaucoma and the studies showing some effect of stress on intraocular pressure stress the relevance of psychological support for glaucoma patients, who are confronted with a disease with a high longterm risk of blindness. Georg Thieme Verlag KG Stuttgart · New York.

No Elevated Plasma Catecholamine Levels during Sleep in Newly Diagnosed, Untreated Hypertensives

PubMed Central

Rasch, Björn; Dodt, Christoph; Sayk, Friedhelm; Mölle, Matthias; Born, Jan

2011-01-01

The sympatho-adrenergic system is highly involved in regulating sleep, wake and arousal states, and abnormalities in this system are regarded as a key factor in the development and progression of arterial hypertension. While hypertension is associated with a hyperadrenergic state during wakefulness, the effect of hypertension on plasma-catecholamine levels during sleep is not yet known. Twelve young participants with newly diagnosed, untreated hypertension and twelve healthy controls slept for 7 hours in the sleep laboratory. Before and after sleep, subjects rested in a supine position for 3-h periods of wakefulness. We sampled blood at a fast rate (1/10 min) and monitored blood pressure and heart rate continuously. We show that plasma NE and E levels did not differ between hypertensives and normotensive during sleep as well as before and after sleep. Blood pressure was higher in hypertensives, reaching the largest group difference in the morning after sleep. Unlike in the normotensives, in the hypertensive participants the morning rise in blood pressure did not correlate with the rise in catecholamine levels at awakening. Our results suggest that hypertension in its early stages is not associated with a strong hyperadrenergic state during sleep. In showing a diminished control of blood pressure through sympatho-adrenergic signals in hypertensive participants, our data point towards a possible involvement of dysfunctional sleep-related blood pressure regulation in the development of hypertension. PMID:21695061

Pediatric idiopathic intracranial hypertension - Is the fixed threshold value of elevated LP opening pressure set too high?

PubMed

Gerstl, Lucia; Schoppe, Nikola; Albers, Lucia; Ertl-Wagner, Birgit; Alperin, Noam; Ehrt, Oliver; Pomschar, Andreas; Landgraf, Mirjam N; Heinen, Florian

2017-11-01

Idiopathic intracranial hypertension (IIH) in children is a rare condition of unknown etiology and various clinical presentations. The primary aim of this study was to evaluate if our pediatric IIH study group fulfilled the revised diagnostic criteria for IIH published in 2013, particularly with regard to clinical presentation and threshold value of an elevated lumbar puncture opening pressure. Additionally we investigated the potential utilization of MR-based and fundoscopic methods of estimating intracranial pressure for improved diagnosis. Clinical data were collected retrospectively from twelve pediatric patients diagnosed with IIH between 2008 and 2012 and revised diagnostic criteria were applied. Comparison with non-invasive methods for measuring intracranial pressure, MRI-based measurement (MR-ICP) and venous ophthalmodynamometry was performed. Only four of the twelve children (33%) fulfilled the revised diagnostic criteria for a definite diagnosis of IIH. Regarding noninvasive methods, MR-ICP (n = 6) showed a significantly higher mean of intracranial pressure compared to a healthy age- and sex-matched control group (p = 0.0043). Venous ophthalmodynamometry (n = 4) showed comparable results to invasive lumbar puncture. The revised diagnostic criteria for IIH may be too strict especially in children without papilledema. MR-ICP and venous ophthalmodynamometry are promising complementary procedures for monitoring disease progression and response to treatment. Copyright © 2017 European Paediatric Neurology Society. Published by Elsevier Ltd. All rights reserved.

Influence of temporal pressure constraint on the biomechanical organization of gait initiation made with or without an obstacle to clear.

PubMed

Yiou, Eric; Fourcade, Paul; Artico, Romain; Caderby, Teddy

2016-06-01

Many daily motor tasks have to be performed under a temporal pressure constraint. This study aimed to explore the influence of such constraint on motor performance and postural stability during gait initiation. Young healthy participants initiated gait at maximal velocity under two conditions of temporal pressure: in the low-pressure condition, gait was self-initiated (self-initiated condition, SI); in the high-pressure condition, it was initiated as soon as possible after an acoustic signal (reaction-time condition, RT). Gait was initiated with and without an environmental constraint in the form of an obstacle to be cleared placed in front of participants. Results showed that the duration of postural adjustments preceding swing heel-off ("anticipatory postural adjustments", APAs) was shorter, while their amplitude was larger in RT compared to SI. These larger APAs allowed the participants to reach equivalent postural stability and motor performance in both RT and SI. In addition, the duration of the execution phase of gait initiation increased greatly in the condition with an obstacle to be cleared (OBST) compared to the condition without an obstacle (NO OBST), thereby increasing lateral instability and thus involving larger mediolateral APA. Similar effects of temporal pressure were obtained in NO OBST and OBST. This study shows the adaptability of the postural system to temporal pressure in healthy young adults initiating gait. The outcome of this study may provide a basis for better understanding the aetiology of balance impairments with the risk of falling in frail populations while performing daily complex tasks involving a whole-body progression.

Visible/near-infrared spectra of experimentally shocked plagioclase feldspars

USGS Publications Warehouse

Johnson, J. R.; Horz, F.

2003-01-01

High shock pressures cause structural changes in plagioclase feldspars such as mechanical fracturing and disaggregation of the crystal lattice at submicron scales, the formation of diaplectic glass (maskelynite), and genuine melting. Past studies of visible/ near-infrared spectra of shocked feldspars demonstrated few spectral variations with pressure except for a decrease in the depth of the absorption feature near 1250-1300 nm and an overall decrease in reflectance. New visible/near-infrared spectra (400-2500 nm) of experimentally shocked (17-56 GPa) albite- and anorthite-rich rock powders demonstrate similar trends, including the loss of minor hydrated mineral bands near 1410, 1930, 2250, and 2350 nm. However, the most interesting new observations are increases in reflectance at intermediate pressures, followed by subsequent decreases in reflectance at higher pressures. The amount of internal scattering and overall sample reflectance is controlled by the relative proportions of micro-fractures, submicron grains, diaplectic glass, and melts formed during shock metamorphism. We interpret the observed reflectance increases at intermediate pressures to result from progressively larger proportions of submicron feldspar grains and diaplectic glass. The ensuing decreases in reflectance occur after diaplectic glass formation is complete and the proportion of genuine melt inclusions increases. The pressure regimes over which these reflectance variations occur differ between albite and anorthite, consistent with thermal infrared spectra of these samples and previous studies of shocked feldspars. These types of spectral variations associated with different peak shock pressures should be considered during interpretation and modeling of visible/near-infrared remotely sensed spectra of planetary and asteroidal surfaces.

Studies of Methane Counterflow Flames at Low Pressures

NASA Astrophysics Data System (ADS)

Burrell, Robert Roe

Methane is the smallest hydrocarbon molecule, the fuel most widely studied in fundamental flame structure studies, and a major component of natural gas. Despite many decades of research into the fundamental chemical kinetics involved in methane oxidation, ongoing advancements in research suggest that more progress can be made. Though practical combustors of industrial and commercial significance operate at high pressures and turbulent flow conditions, fundamental understanding of combustion chemistry in flames is more readily obtained for low pressure and laminar flow conditions. Measurements were performed from 1 to 0.1 atmospheres for premixed methane/air and non-premixed methane-nitrogen/oxygen flames in a counterflow. Comparative modeling with quasi-one-dimensional strained flame codes revealed bias-induced errors in measured velocities up to 8% at 0.1 atmospheres due to tracer particle phase velocity slip in the low density gas reacting flow. To address this, a numerically-assisted correction scheme consisting of direct simulation of the particle phase dynamics in counterflow was implemented. Addition of reactions describing the prompt dissociation of formyl radicals to an otherwise unmodified USC Mech II kinetic model was found to enhance computed flame reactivity and substantially improve the predictive capability of computed results for measurements at the lowest pressures studied. Yet, the same modifications lead to overprediction of flame data at 1 atmosphere where results from the unmodified USC Mech II kinetic mechanism agreed well with ambient pressure flame data. The apparent failure of a single kinetic model to capture pressure dependence in methane flames motivates continued skepticism regarding the current understanding of pressure dependence in kinetic models, even for the simplest fuels.

Evaluation of Acoustic Emission SHM of PRSEUS Composite Pressure Cube Tests

NASA Technical Reports Server (NTRS)

Horne, Michael R.; Madaras, Eric I.

2013-01-01

A series of tests of the Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) pressure cube were conducted during third quarter 2011 at NASA Langley Research Center (LaRC) in the Combined Loads Test facility (COLTS). This is a report of the analysis of the Acoustic Emission (AE) data collected during those tests. The AE signals of the later tests are consistent with the final failure progression through two of the pressure cube panels. Calibration tests and damage precursor AE indications, from preliminary checkout pressurizations, indicated areas of concern that eventually failed. Hence those tests have potential for vehicle health monitoring.

Brain Network Activation in Patients With Movement Disorders

ClinicalTrials.gov

2017-08-29

Parkinson Disease; Essential Tremor; Dystonia; Normal Pressure Hydrocephalus; Cerebellar Ataxia; Multiple System Atrophy; Progressive Supranuclear Palsy; Corticobasal Degeneration; Dementia With Lewy Bodies

Tube failures in moisture separator-reheater tube bundles due to restrained thermal expansion

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

Heilker, W.J.; Cassell, D.S.

1983-01-01

In a nuclear power plant, moisture separator-reheater components (MSRs) are used to dry and superheat the exhaust steam from the high pressure turbine before admitting this steam to the low pressure turbines. MSRs have experienced numerous problems which have caused loss of plant thermal efficiency, poor unit availability and high maintenance costs. The most serious problem has been the progressive failure of the U-tubes, which has necessitated replacement of MSR tube bundles at several plants. This paper presents an explanation of the failure mode and identifies critical operational and geometric parameters as to their respective roles in the process. Detailedmore » thermal-hydraulic analytic modeling enables the calculation of tube wall temperatures along the length of each tube for selected power levels. These temperature data are input to finite element models of the tube bundle which yield interactive displacements, rotations and stresses. The results of these studies provide the rational basis for the tube failure mechanism, which is supported by data acquired from inspection of in-service MSRs.« less

Evolutionary Inference across Eukaryotes Identifies Specific Pressures Favoring Mitochondrial Gene Retention.

PubMed

Johnston, Iain G; Williams, Ben P

2016-02-24

Since their endosymbiotic origin, mitochondria have lost most of their genes. Although many selective mechanisms underlying the evolution of mitochondrial genomes have been proposed, a data-driven exploration of these hypotheses is lacking, and a quantitatively supported consensus remains absent. We developed HyperTraPS, a methodology coupling stochastic modeling with Bayesian inference, to identify the ordering of evolutionary events and suggest their causes. Using 2015 complete mitochondrial genomes, we inferred evolutionary trajectories of mtDNA gene loss across the eukaryotic tree of life. We find that proteins comprising the structural cores of the electron transport chain are preferentially encoded within mitochondrial genomes across eukaryotes. A combination of high GC content and high protein hydrophobicity is required to explain patterns of mtDNA gene retention; a model that accounts for these selective pressures can also predict the success of artificial gene transfer experiments in vivo. This work provides a general method for data-driven inference of the ordering of evolutionary and progressive events, here identifying the distinct features shaping mitochondrial genomes of present-day species. Copyright © 2016 Elsevier Inc. All rights reserved.

Stress remagnetization in pyrrhotite-calcite synthetic aggregates

NASA Astrophysics Data System (ADS)

Robion, Philippe; Borradaile, Graham J.

2001-01-01

Stress-induced remagnetization has been applied to multidomain pyrrhotite-calcite synthetic aggregates in a triaxial rig. Experimental deformation used 150MPa confining pressure, a constant strain rate of 10-5 s-1 and applied differential stresses of up to 70MPa. New components of magnetization, parallel to the direction of the pressure vessel field, were added to the pre-deformational magnetization. The intensity of remagnetization (M'-M0) increases with the intensity of the applied differential stress and affects the coercivity fraction below 15mT. Bulk shortening is less than 8 per cent, thus grain rotation cannot explain selective remagnetization of the low-coercivity fraction. Remagnetization is thus attributed to deformational viscous remanent magnetization (DVRM). It is observed that high-coercivity (>15mT) grains do not remagnetize. There is, however, slight progressive rotation of pre-deformational magnetization with increasing strain up to 8 per cent of bulk shortening. The lack of piezoremanent magnetization in the high-coercivity range may be due to defects introduced in pyrrhotite during sample preparation. Experiments using synthetic pyrrhotite, expected to show low dislocation densities, would be necessary to test this effect.

Upcoming Methods and Specifications of Continuous Intraocular Pressure Monitoring Systems for Glaucoma

PubMed Central

Molaei, Amir; Karamzadeh, Vahid; Safi, Sare; Esfandiari, Hamed; Dargahi, Javad; Khosravi, Mohammad Azam

2018-01-01

Glaucoma is the leading cause of irreversible blindness and vision loss in the world. Although intraocular pressure (IOP) is no longer considered the only risk factor for glaucoma, it is still the most important one. In most cases, high IOP is secondary to trabecular meshwork dysfunction. High IOP leads to compaction of the lamina cribrosa and subsequent damage to retinal ganglion cell axons. Damage to the optic nerve head is evident on funduscopy as posterior bowing of the lamina cribrosa and increased cupping. Currently, the only documented method to slow or halt the progression of this disease is to decrease the IOP; hence, accurate IOP measurement is crucial not only for diagnosis, but also for the management. Due to the dynamic nature and fluctuation of the IOP, a single clinical measurement is not a reliable indicator of diurnal IOP; it requires 24-hour monitoring methods. Technological advances in microelectromechanical systems and microfluidics provide a promising solution for the effective measurement of IOP. This paper provides a broad overview of the upcoming technologies to be used for continuous IOP monitoring. PMID:29403593

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

High pressure cosmochemistry applied to major planetary interiors: Experimental studies

NASA Technical Reports Server (NTRS)

Nicol, M. F.; Johnson, M.; Koumvakalis, A. S.

1984-01-01

Progress is reported on a project to determine the properties and boundaries of high pressure phases of the H2-He-H2O-NH3-CH4 system that are needed to constrain theoretical models of the interiors of the major planets. This project is one of the first attempts to measure phase equilibria in binary fluid-solid systems in diamond anvil cells. Vibrational spectroscopy, direct visual observations, and X-ray diffraction crystallography of materials confined in externally heated cells are the primary experimental probes. Adiabats of these materials are also measured in order to constrain models of heat flow in these bodies and to detect phase transitions by thermal anomalies. Initial efforts involve the NH3-H2O binary. This system is especially relevant to models for surface reconstruction of the icy satellites of Jupiter and Saturn. Thermal analysis experiments were completed for the P-X space, p4GPa:0 or = 0.50, near room temperature. The cryostat, sample handling equipment, and optics needed to extend the optical P-T-X work below room temperature was completed.

Cardioprotection and lifespan extension by the natural polyamine spermidine

PubMed Central

Eisenberg, Tobias; Abdellatif, Mahmoud; Schroeder, Sabrina; Primessnig, Uwe; Stekovic, Slaven; Pendl, Tobias; Harger, Alexandra; Schipke, Julia; Zimmermann, Andreas; Schmidt, Albrecht; Tong, Mingming; Ruckenstuhl, Christoph; Dammbrueck, Christopher; Gross, Angelina S.; Herbst, Viktoria; Magnes, Christoph; Trausinger, Gert; Narath, Sophie; Meinitzer, Andreas; Hu, Zehan; Kirsch, Alexander; Eller, Kathrin; Gutierrez, Didac-Carmona; Büttner, Sabrina; Pietrocola, Federico; Knittelfelder, Oskar; Schrepfer, Emilie; Rockenfeller, Patrick; Simonini, Corinna; Rahn, Alexandros; Horsch, Marion; Moreth, Kristin; Beckers, Johannes; Fuchs, Helmut; Gailus-Durner, Valerie; Neff, Frauke; Janik, Dirk; Rathkolb, Birgit; Rozman, Jan; de Angelis, Martin Hrabe; Moustafa, Tarek; Haemmerle, Guenter; Mayr, Manuel; Willeit, Peter; von Frieling-Salewsky, Marion; Pieske, Burkert; Scorrano, Luca; Pieber, Thomas; Pechlaner, Raimund; Willeit, Johann; Sigrist, Stephan J.; Linke, Wolfgang A.; Mühlfeld, Christian; Sadoshima, Junichi; Dengjel, Joern; Kiechl, Stefan; Kroemer, Guido; Sedej, Simon; Madeo, Frank

2018-01-01

Aging is associated with an increased risk of cardiovascular disease and death. Here we show that oral supplementation of the natural polyamine spermidine extends the lifespan of mice and exerts cardioprotective effects, reducing cardiac hypertrophy and preserving diastolic function in old mice. Spermidine feeding enhanced cardiac autophagy, mitophagy and mitochondrial respiration, and it also improved the mechano-elastical properties of cardiomyocytes in vivo, coinciding with increased titin phosphorylation and suppressed subclinical inflammation. Spermidine feeding failed to provide cardioprotection in mice that lack the autophagy-related protein Atg5 in cardiomyocytes. In Dahl salt-sensitive rats that were fed a high-salt diet, a model for hypertension-induced congestive heart failure, spermidine feeding reduced systemic blood pressure, increased titin phosphorylation and prevented cardiac hypertrophy and a decline in diastolic function, thus delaying the progression to heart failure. In humans, high levels of dietary spermidine, as assessed from food questionnaires, correlated with reduced blood pressure and a lower incidence of cardiovascular disease. Our results suggest a new and feasible strategy for the protection from cardiovascular disease. PMID:27841876

Three-dimensional characterisation and simulation of deformation and damage during Taylor impact in PTFE

NASA Astrophysics Data System (ADS)

Resnyansky, A. D.; McDonald, S. A.; Withers, P. J.; Bourne, N. K.; Millett, J. C. F.; Brown, E. N.; Rae, P. J.

2014-05-01

The current work presents Taylor impact experiments interrogating the effect of dynamic, high-pressure loading on polytetrafluoroethylene (PTFE). In particular, X-ray microtomography has been used to characterise the damage imparted to cylindrical samples due to impact at different velocities. Distinct regions of deformation are present and controlled by fracture within the polymer, with the extent of the deformed region and increasing propagation of fractures from the impact face showing a clear trend with increasing impact velocity. A two-phase rate sensitive strength model is implemented in the CTH hydrocode and used for simulation of the problem. The high-pressure phase transition of PTFE into Phase III within the crystalline domains from the polymer at normal conditions is managed by suitable phase transition kinetics within the model. The experimental observations are discussed with respect to the multi-phase model hydrocode predictions of the shock response from Taylor impact simulations. The damage and its progress are shown to correlate well with the onset of the phase transition and its evolution following the impact velocity increase.

Left Ventricular Geometry and Blood Pressure as Predictors of Adverse Progression of Fabry Cardiomyopathy.

PubMed

Krämer, Johannes; Bijnens, Bart; Störk, Stefan; Ritter, Christian O; Liu, Dan; Ertl, Georg; Wanner, Christoph; Weidemann, Frank

2015-01-01

In spite of several research studies help to describe the heart in Fabry disease (FD), the cardiomyopathy is not entirely understood. In addition, the impact of blood pressure and alterations in geometry have not been systematically evaluated. In 74 FD patients (mean age 36±12 years; 45 females) the extent of myocardial fibrosis and its progression were quantified using cardiac magnetic-resonance-imaging with late enhancement technique (LE). Results were compared to standard echocardiography complemented by 2D-speckle-tracking, 3D-sphericity-index (SI) and standardized blood pressure measurement. At baseline, no patient received enzyme replacement therapy (ERT). After 51±24 months, a follow-up examination was performed. Systolic blood pressure (SBP) was higher in patients with vs. without LE: 123±17 mmHg vs. 115±13 mmHg; P = 0.04. A positive correlation was found between SI and the amount of LE-positive myocardium (r = 0.51; P<0.001) indicating an association of higher SI in more advanced stages of the cardiomyopathy. SI at baseline was positively associated with the increase of LE-positive myocardium during follow-up. The highest SBP (125±19 mmHg) and also the highest SI (0.32±0.05) was found in the subgroup with a rapidly increasing LE (ie, ≥0.2% per year; n = 16; P = 0.04). Multivariate logistic regression analysis including SI, SBP, EF, left ventricular volumes, wall thickness and NT-proBNP adjusted for age and sex showed SI as the most powerful parameter to detect rapid progression of LE (AUC = 0.785; P<0.05). LV geometry as assessed by the sphericity index is altered in relation to the stage of the Fabry cardiomyopathy. Although patients with FD are not hypertensive, the SBP has a clear impact on the progression of the cardiomyopathy.

Left Ventricular Geometry and Blood Pressure as Predictors of Adverse Progression of Fabry Cardiomyopathy

PubMed Central

Krämer, Johannes; Bijnens, Bart; Störk, Stefan; Ritter, Christian O.; Liu, Dan; Ertl, Georg; Wanner, Christoph; Weidemann, Frank

2015-01-01

Background In spite of several research studies help to describe the heart in Fabry disease (FD), the cardiomyopathy is not entirely understood. In addition, the impact of blood pressure and alterations in geometry have not been systematically evaluated. Methods In 74 FD patients (mean age 36±12 years; 45 females) the extent of myocardial fibrosis and its progression were quantified using cardiac magnetic-resonance-imaging with late enhancement technique (LE). Results were compared to standard echocardiography complemented by 2D-speckle-tracking, 3D-sphericity-index (SI) and standardized blood pressure measurement. At baseline, no patient received enzyme replacement therapy (ERT). After 51±24 months, a follow-up examination was performed. Results Systolic blood pressure (SBP) was higher in patients with vs. without LE: 123±17 mmHg vs. 115±13 mmHg; P = 0.04. A positive correlation was found between SI and the amount of LE-positive myocardium (r = 0.51; P<0.001) indicating an association of higher SI in more advanced stages of the cardiomyopathy. SI at baseline was positively associated with the increase of LE-positive myocardium during follow-up. The highest SBP (125±19 mmHg) and also the highest SI (0.32±0.05) was found in the subgroup with a rapidly increasing LE (ie, ≥0.2% per year; n = 16; P = 0.04). Multivariate logistic regression analysis including SI, SBP, EF, left ventricular volumes, wall thickness and NT-proBNP adjusted for age and sex showed SI as the most powerful parameter to detect rapid progression of LE (AUC = 0.785; P<0.05). Conclusions LV geometry as assessed by the sphericity index is altered in relation to the stage of the Fabry cardiomyopathy. Although patients with FD are not hypertensive, the SBP has a clear impact on the progression of the cardiomyopathy. PMID:26600044

Molybdenum-copper and tungsten-copper alloys and method of making

DOEpatents

Schmidt, F.A.; Verhoeven, J.D.; Gibson, E.D.

1989-05-23

Molybdenum-copper and tungsten-copper alloys are prepared by a consumable electrode method in which the electrode consists of a copper matrix with embedded strips of refractory molybdenum or tungsten. The electrode is progressively melted at its lower end with a superatmospheric inert gas pressure maintained around the liquefying electrode. The inert gas pressure is sufficiently above the vapor pressure of copper at the liquidus temperature of the alloy being formed to suppress boiling of liquid copper. 6 figs.

DNS of Low-Pressure Turbine Cascade Flows with Elevated Inflow Turbulence Using a Discontinuous-Galerkin Spectral-Element Method

NASA Technical Reports Server (NTRS)

Garai, Anirban; Diosady, Laslo T.; Murman, Scott M.; Madavan, Nateri K.

2016-01-01

Recent progress towards developing a new computational capability for accurate and efficient high-fidelity direct numerical simulation (DNS) and large-eddy simulation (LES) of turbomachinery is described. This capability is based on an entropy- stable Discontinuous-Galerkin spectral-element approach that extends to arbitrarily high orders of spatial and temporal accuracy, and is implemented in a computationally efficient manner on a modern high performance computer architecture. An inflow turbulence generation procedure based on a linear forcing approach has been incorporated in this framework and DNS conducted to study the effect of inflow turbulence on the suction- side separation bubble in low-pressure turbine (LPT) cascades. The T106 series of airfoil cascades in both lightly (T106A) and highly loaded (T106C) configurations at exit isentropic Reynolds numbers of 60,000 and 80,000, respectively, are considered. The numerical simulations are performed using 8th-order accurate spatial and 4th-order accurate temporal discretization. The changes in separation bubble topology due to elevated inflow turbulence is captured by the present method and the physical mechanisms leading to the changes are explained. The present results are in good agreement with prior numerical simulations but some expected discrepancies with the experimental data for the T106C case are noted and discussed.

Low-dose hydralazine prevents fibrosis in a murine model of acute kidney injury-to-chronic kidney disease progression.

PubMed

Tampe, Björn; Steinle, Ulrike; Tampe, Désirée; Carstens, Julienne L; Korsten, Peter; Zeisberg, Elisabeth M; Müller, Gerhard A; Kalluri, Raghu; Zeisberg, Michael

2017-01-01

Acute kidney injury (AKI) and progressive chronic kidney disease (CKD) are intrinsically tied syndromes. In this regard, the acutely injured kidney often does not achieve its full regenerative capacity and AKI directly transitions into progressive CKD associated with tubulointerstitial fibrosis. Underlying mechanisms of such AKI-to-CKD progression are still incompletely understood and specific therapeutic interventions are still elusive. Because epigenetic modifications play a role in maintaining tissue fibrosis, we used a murine model of ischemia-reperfusion injury to determine whether aberrant promoter methylation of RASAL1 contributes causally to the switch between physiological regeneration and tubulointerstitial fibrogenesis, a hallmark of AKI-to-CKD progression. It is known that the antihypertensive drug hydralazine has demethylating activity, and that its optimum demethylating activity occurs at concentrations below blood pressure-lowering doses. Administration of low-dose hydralazine effectively induced expression of hydroxylase TET3, which catalyzed RASAL1 hydroxymethylation and subsequent RASAL1 promoter demethylation. Hydralazine-induced CpG promoter demethylation subsequently attenuated renal fibrosis and preserved excretory renal function independent of its blood pressure-lowering effects. In comparison, RASAL1 demethylation and inhibition of tubulointerstitial fibrosis was not detected upon administration of the angiotensin-converting enzyme inhibitor Ramipril in this model. Thus, RASAL1 promoter methylation and subsequent transcriptional RASAL1 suppression plays a causal role in AKI-to-CKD progression. Copyright © 2016 International Society of Nephrology. Published by Elsevier Inc. All rights reserved.

Prognostic significance of day-by-day variability of home blood pressure on progression to macroalbuminuria in patients with diabetes.

PubMed

Ushigome, Emi; Matsumoto, Shinobu; Oyabu, Chikako; Kitagawa, Noriyuki; Tanaka, Toru; Hasegawa, Goji; Ohnishi, Masayoshi; Tsunoda, Sei; Ushigome, Hidetaka; Yokota, Isao; Nakamura, Naoto; Oda, Yohei; Asano, Mai; Tanaka, Muhei; Yamazaki, Masahiro; Fukui, Michiaki

2018-05-01

Previously, we have shown in cross-sectional analysis of patients with type 2 diabetes mellitus that the presence of diabetic nephropathy is associated with increased home blood pressure (HBP) variability. We now examine the prognostic significance of HBP variability in substantially the same cohort. We performed a prospective cohort study of type 2 diabetes patients. We analyzed 714 patients. Major exclusion criteria are missing data of urinary albumin excretion and newly prescribed or stopped renin-angiotensin system inhibitors during 2-year follow-up. Patients were instructed to perform triplicate morning and evening HBP measurements for 14 consecutive days. We computed day-by-day HBP variability as within-patient standard deviation (SD) and coefficient of variation (CV) of measurements. During the follow-up period of 2 years, 23 patients progressed to macroalbuminuria. The changing risk of progression to macroalbuminuria with increasing day-by-day variability of morning SBP was better depicted using smoothing spline analyses. Patients with greater SD of morning SBP tended to significantly progress to macroalbuminuria [odds ratio: 5.24 (95% confidence interval: 2.10-13.03; P > 0.001)]. Patients with greater CV of morning SBP also tended to significantly progress to macroalbuminuria [odds ratio: 3.36 (95% confidence interval: 1.39-8.12; P = 0.007)]. Day-by-day variability of morning SBP was proven as an independent predictor for progression to macroalbuminuria in patients with type 2 diabetes.

A Biodiversity Indicators Dashboard: Addressing Challenges to Monitoring Progress towards the Aichi Biodiversity Targets Using Disaggregated Global Data

PubMed Central

Han, Xuemei; Smyth, Regan L.; Young, Bruce E.; Brooks, Thomas M.; Sánchez de Lozada, Alexandra; Bubb, Philip; Butchart, Stuart H. M.; Larsen, Frank W.; Hamilton, Healy; Hansen, Matthew C.; Turner, Will R.

2014-01-01

Recognizing the imperiled status of biodiversity and its benefit to human well-being, the world's governments committed in 2010 to take effective and urgent action to halt biodiversity loss through the Convention on Biological Diversity's “Aichi Targets”. These targets, and many conservation programs, require monitoring to assess progress toward specific goals. However, comprehensive and easily understood information on biodiversity trends at appropriate spatial scales is often not available to the policy makers, managers, and scientists who require it. We surveyed conservation stakeholders in three geographically diverse regions of critical biodiversity concern (the Tropical Andes, the African Great Lakes, and the Greater Mekong) and found high demand for biodiversity indicator information but uneven availability. To begin to address this need, we present a biodiversity “dashboard” – a visualization of biodiversity indicators designed to enable tracking of biodiversity and conservation performance data in a clear, user-friendly format. This builds on previous, more conceptual, indicator work to create an operationalized online interface communicating multiple indicators at multiple spatial scales. We structured this dashboard around the Pressure-State-Response-Benefit framework, selecting four indicators to measure pressure on biodiversity (deforestation rate), state of species (Red List Index), conservation response (protection of key biodiversity areas), and benefits to human populations (freshwater provision). Disaggregating global data, we present dashboard maps and graphics for the three regions surveyed and their component countries. These visualizations provide charts showing regional and national trends and lay the foundation for a web-enabled, interactive biodiversity indicators dashboard. This new tool can help track progress toward the Aichi Targets, support national monitoring and reporting, and inform outcome-based policy-making for the protection of natural resources. PMID:25409183

A biodiversity indicators dashboard: addressing challenges to monitoring progress towards the Aichi biodiversity targets using disaggregated global data.

PubMed

Han, Xuemei; Smyth, Regan L; Young, Bruce E; Brooks, Thomas M; Sánchez de Lozada, Alexandra; Bubb, Philip; Butchart, Stuart H M; Larsen, Frank W; Hamilton, Healy; Hansen, Matthew C; Turner, Will R

2014-01-01

Recognizing the imperiled status of biodiversity and its benefit to human well-being, the world's governments committed in 2010 to take effective and urgent action to halt biodiversity loss through the Convention on Biological Diversity's "Aichi Targets". These targets, and many conservation programs, require monitoring to assess progress toward specific goals. However, comprehensive and easily understood information on biodiversity trends at appropriate spatial scales is often not available to the policy makers, managers, and scientists who require it. We surveyed conservation stakeholders in three geographically diverse regions of critical biodiversity concern (the Tropical Andes, the African Great Lakes, and the Greater Mekong) and found high demand for biodiversity indicator information but uneven availability. To begin to address this need, we present a biodiversity "dashboard"--a visualization of biodiversity indicators designed to enable tracking of biodiversity and conservation performance data in a clear, user-friendly format. This builds on previous, more conceptual, indicator work to create an operationalized online interface communicating multiple indicators at multiple spatial scales. We structured this dashboard around the Pressure-State-Response-Benefit framework, selecting four indicators to measure pressure on biodiversity (deforestation rate), state of species (Red List Index), conservation response (protection of key biodiversity areas), and benefits to human populations (freshwater provision). Disaggregating global data, we present dashboard maps and graphics for the three regions surveyed and their component countries. These visualizations provide charts showing regional and national trends and lay the foundation for a web-enabled, interactive biodiversity indicators dashboard. This new tool can help track progress toward the Aichi Targets, support national monitoring and reporting, and inform outcome-based policy-making for the protection of natural resources.

Effects of Topical Latanoprost on Intraocular Pressure and Myopia Progression in Young Guinea Pigs

PubMed Central

El-Nimri, Nevin W.; Wildsoet, Christine F.

2018-01-01

Purpose To determine whether latanoprost, a prostaglandin analog proven to be very effective in reducing intraocular pressure (IOP) in humans, can also slow myopia progression in the guinea pig form deprivation (FD) model. Methods Two-week-old pigmented guinea pigs underwent monocular FD and daily topical latanoprost (0.005%, n = 10) or artificial tears (control, n = 10) starting 1 week after the initiation of FD, with all treatments continuing for a further 9 weeks. Tonometry, retinoscopy, and high-frequency A-scan ultrasonography were used to monitor IOP, refractive error, and ocular axial dimensions, respectively. Results Latanoprost significantly reduced IOP and slowed myopia progression. Mean interocular IOP differences (±SEM) recorded at baseline and week 10 were −0.30 ± 0.51 and 1.80 ± 1.16 mm Hg (P = 0.525) for the control group and 0.07 ± 0.35 and −5.17 ± 0.96 mm Hg (P < 0.001) for the latanoprost group. Equivalent interocular differences for optical axial length at baseline and week 10 were 0.00 ± 0.015 and 0.29 ± 0.04 mm (P < 0.001; control) and 0.02 ± 0.02 and 0.06 ± 0.02 mm (P = 0.202; latanoprost), and for refractive error were +0.025 ± 0.36 and −8.2 ± 0.71 diopter (D) (P < 0.001; control), and −0.15 ± 0.35 and −2.25 ± 0.54 D (P = 0.03; latanoprost). Conclusions In the FD guinea pig model, latanoprost significantly reduces the development of myopia. Although further investigations into underlying mechanisms are needed, the results open the exciting possibility of a new line of myopia control therapy. PMID:29847673

Progress on DCLL Blanket Concept

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

Wong, Clement; Abdou, M.; Katoh, Yutai

2013-09-01

Under the US Fusion Nuclear Science and Technology Development program, we have selected the Dual Coolant Lead Lithium concept (DCLL) as a reference blanket, which has the potential to be a high performance DEMO blanket design with a projected thermal efficiency of >40%. Reduced activation ferritic/martensitic (RAF/M) steel is used as the structural material. The self-cooled breeder PbLi is circulated for power conversion and for tritium breeding. A SiC-based flow channel insert (FCI) is used as a means for magnetohydrodynamic pressure drop reduction from the circulating liquid PbLi and as a thermal insulator to separate the high-temperature PbLi (~700°C) frommore » the helium-cooled RAF/M steel structure. We are making progress on related R&D needs to address critical Fusion Nuclear Science and Facility (FNSF) and DEMO blanket development issues. When performing the function as the Interface Coordinator for the DCLL blanket concept, we had been developing the mechanical design and performing neutronics, structural and thermal hydraulics analyses of the DCLL TBM module. We had estimated the necessary ancillary equipment that will be needed at the ITER site and a detailed safety impact report has been prepared. This provided additional understanding of the DCLL blanket concept in preparation for the FNSF and DEMO. This paper will be a summary report on the progress of the DCLL TBM design and R&Ds for the DCLL blanket concept.« less

Boron Nitride Nanotube: Synthesis and Applications

NASA Technical Reports Server (NTRS)

Tiano, Amanda L.; Park, Cheol; Lee, Joseph W.; Luong, Hoa H.; Gibbons, Luke J.; Chu, Sang-Hyon; Applin, Samantha I.; Gnoffo, Peter; Lowther, Sharon; Kim, Hyun Jung;

Boron nitride nanotube: synthesis and applications

NASA Astrophysics Data System (ADS)

Tiano, Amanda L.; Park, Cheol; Lee, Joseph W.; Luong, Hoa H.; Gibbons, Luke J.; Chu, Sang-Hyon; Applin, Samantha; Gnoffo, Peter; Lowther, Sharon; Kim, Hyun Jung; Danehy, Paul M.; Inman, Jennifer A.; Jones, Stephen B.; Kang, Jin Ho; Sauti, Godfrey; Thibeault, Sheila A.; Yamakov, Vesselin; Wise, Kristopher E.; Su, Ji; Fay, Catharine C.

2014-04-01

Scientists have predicted that carbon's immediate neighbors on the periodic chart, boron and nitrogen, may also form perfect nanotubes, since the advent of carbon nanotubes (CNTs) in 1991. First proposed then synthesized by researchers at UC Berkeley in the mid 1990's, the boron nitride nanotube (BNNT) has proven very difficult to make until now. Herein we provide an update on a catalyst-free method for synthesizing highly crystalline, small diameter BNNTs with a high aspect ratio using a high power laser under a high pressure and high temperature environment first discovered jointly by NASA/NIA/JSA. Progress in purification methods, dispersion studies, BNNT mat and composite formation, and modeling and diagnostics will also be presented. The white BNNTs offer extraordinary properties including neutron radiation shielding, piezoelectricity, thermal oxidative stability (> 800°C in air), mechanical strength, and toughness. The characteristics of the novel BNNTs and BNNT polymer composites and their potential applications are discussed.

Thermodynamic properties and equations of state for Ag, Al, Au, Cu and MgO using a lattice vibrational method

NASA Astrophysics Data System (ADS)

Jacobs, M.; Schmid-Fetzer, R.

2012-04-01

A prerequisite for the determination of pressure in static high pressure measurements, such as in diamond anvil cells is the availability of accurate equations of state for reference materials. These materials serve as luminescence gauges or as X-ray gauges and equations of state for these materials serve as secondary pressure scales. Recently, successful progress has been made in the development of consistency between static, dynamic shock-wave and ultrasonic measurements of equations of state (e.g. Dewaele et al. Phys. Rev. B70, 094112, 2004, Dorogokupets and Oganov, Doklady Earth Sciences, 410, 1091-1095, 2006, Holzapfel, High Pressure Research 30, 372-394, 2010) allowing testing models to arrive at consistent thermodynamic descriptions for X-ray gauges. Apart from applications of metallic elements in high-pressure work, thermodynamic properties of metallic elements are also of mandatory interest in the field of metallurgy for studying phase equilibria of alloys, kinetics of phase transformation and diffusion related problems, requiring accurate thermodynamic properties in the low pressure regime. Our aim is to develop a thermodynamic data base for metallic alloy systems containing Ag, Al, Au, Cu, Fe, Ni, Pt, from which volume properties in P-T space can be predicted when it is coupled to vibrational models. This mandates the description of metallic elements as a first step aiming not only at consistency in the pressure scales for the elements, but also at accurate representations of thermodynamic properties in the low pressure regime commonly addressed in metallurgical applications. In previous works (e.g. Jacobs and de Jong, Geochim. Cosmochim. Acta, 71, 3630-3655, 2007, Jacobs and van den Berg, Phys. Earth Planet. Inter., 186, 36-48, 2011) it was demonstrated that a lattice vibrational framework based on Kieffer's model for the vibrational density of states, is suitable to construct a thermodynamic database for Earth mantle materials. Such a database aims at, when coupled to a thermodynamic computation program, the calculation and prediction of phase equilibria and thermo-physical properties of phase equilibrium assemblages in pressure-temperature-composition space. In Jacobs and van den Berg (2011) the vibrational method, together with a thermodynamic data base, was successfully applied to mantle convection of materials in the Earth. These works demonstrate that the vibrational method has the advantages of (1) computational speed, (2) coupling or making comparisons with ab initio methods and (3) making reliable extrapolations to extreme conditions. We present results of thermodynamic analyses, using lattice vibrational methods, of Ag, Al, Au, Cu and MgO covering the pressure and temperature regime of the Earth's interior. We show results on consistency of the pressure scales for these materials using different equations of state, under the constraint that thermodynamic properties in the low-pressure regime are accurately represented.

i-anvils : in situ measurements of pressure, temperature and conductivity in diamond anvil cells

NASA Astrophysics Data System (ADS)

Munsch, P.; Bureau, H.; Kubsky, S.; Meijer, J.; Datchi, F.; Ninet, S.; Estève, I.

2011-12-01

The precise determination of the pressure and temperature conditions during diamond anvils cells (DAC) experiments is of primary importance. Such determinations are critical more especially for the fields corresponding to "low pressures" (<4 GPa) and moderate temperature (600-1500°C). Determining the electrical properties of mantle minerals is also a condition to understand the physics of the Deep Earth. This has to be done in situ at pressures and temperatures relevant for the interior of the Earth. i-anvils allow in situ pressure (P) and temperature (T) measurements in experiments using a DAC. Boron and carbon micro-structures are implanted in the diamond anvil lattice a few micrometers below the surface, the sensors are located a few μm below the center of the diamond culet (sample chamber position). When conductive electrodes are implanted at the position of the sample chamber on the culet of the anvil, instead of P,T sensors, they allow in situ measurements of electrical properties of the loaded sample at high P,T conditions in a DAC. The principle consists of applying an electrical potential across the structures through external contacts placed on the slopes of the anvil. The resistivity of these structures is sensitive to pressure and temperature applied in the sample chamber. The electrical transport properties of the sample can be measured the same way when electrodes have been implanted on the culet. Here we will present our last progresses, more especially using the focus ion beam (FIB) technology to perform contacts and electrodes. Progresses about the i-anvils connexions with the electronic devices will also be shown. We will present the last P and T sensors calibrations. Furnaces are also introduced through Boron implantation into the anvils, allowing the possibility to reach intermediate temperatures between externally heated DAC (up to 1100°C) and laser heated DAC (from 1500°C to a few thousands). Preliminary tests and the interest of such devices will be discussed at the meeting. A new diamond anvil cell has been especially designed for this purpose. This DAC allows in situ spectroscopies and X-Ray characterisation of geological fluids in their equilibrium conditions in the crust and in the upper mantle. Preliminary results will be presented.

Prediction of functional loss in glaucoma from progressive optic disc damage.

PubMed

Medeiros, Felipe A; Alencar, Luciana M; Zangwill, Linda M; Bowd, Christopher; Sample, Pamela A; Weinreb, Robert N

2009-10-01

To evaluate the ability of progressive optic disc damage detected by assessment of longitudinal stereophotographs to predict future development of functional loss in those with suspected glaucoma. The study included 639 eyes of 407 patients with suspected glaucoma followed up for an average of 8.0 years with annual standard automated perimetry visual field and optic disc stereophotographs. All patients had normal and reliable standard automated perimetry results at baseline. Conversion to glaucoma was defined as development of 3 consecutive abnormal visual fields during follow-up. Presence of progressive optic disc damage was evaluated by grading longitudinally acquired simultaneous stereophotographs. Other predictive factors included age, intraocular pressure, central corneal thickness, pattern standard deviation, and baseline stereophotograph grading. Hazard ratios for predicting visual field loss were obtained by extended Cox models, with optic disc progression as a time-dependent covariate. Predictive accuracy was evaluated using a modified R(2) index. Progressive optic disc damage had a hazard ratio of 25.8 (95% confidence interval, 16.0-41.7) and was the most important risk factor for development of visual field loss with an R(2) of 79%. The R(2)s for other predictive factors ranged from 6% to 26%. Presence of progressive optic disc damage on stereophotographs was a highly predictive factor for future development of functional loss in glaucoma. These findings suggest the importance of careful monitoring of the optic disc appearance and a potential role for longitudinal assessment of the optic disc as an end point in clinical trials and as a reference for evaluation of diagnostic tests in glaucoma.

Microtube strip heat exchanger

NASA Astrophysics Data System (ADS)

Doty, F. D.

1991-10-01

This progress report is for the September-October 1991 quarter. We have demonstrated feasibility of higher specific conductance by a factor of five than any other work in high-temperature gas-to-gas exchangers. These laminar-flow, microtube exchangers exhibit extremely low pressure drop compared to alternative compact designs under similar conditions because of their much shorter flow length and larger total flow area for lower flow velocities. The design appears to be amenable to mass production techniques, but considerable process development remains. The reduction in materials usage and the improved heat exchanger performance promise to be of enormous significance in advanced engine designs and in cryogenics.

Chemistry Division annual progress report for period ending April 30, 1993

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

Poutsma, M.L.; Ferris, L.M.; Mesmer, R.E.

1993-08-01

The Chemistry Division conducts basic and applied chemical research on projects important to DOE`s missions in sciences, energy technologies, advanced materials, and waste management/environmental restoration; it also conducts complementary research for other sponsors. The research are arranged according to: coal chemistry, aqueous chemistry at high temperatures and pressures, geochemistry, chemistry of advanced inorganic materials, structure and dynamics of advanced polymeric materials, chemistry of transuranium elements and compounds, chemical and structural principles in solvent extraction, surface science related to heterogeneous catalysis, photolytic transformations of hazardous organics, DNA sequencing and mapping, and special topics.

Exploring K-12 mathematics course progression: implications for collegiate success in Florida

NASA Astrophysics Data System (ADS)

Campbell, Bethany; Varney, Christopher; Wade, Aaron

Increasingly, Florida college students are pressured to change their major as few times as possible and take only required classes, all in order to ``Finish in Four, Save More''. If they fail to do so, they may be subject to penalties such as Excess Hour Fees. Partially as a result of this, students wishing to study STEM are at a significant disadvantage if they enter college unprepared to take calculus their first semester. We explore the various ``paths to success'' to STEM degrees, defined by entering college having taken calculus in high school, starting from fifth grade onwards.

Recent Progress in Heliogyro Solar Sail Structural Dynamics

NASA Technical Reports Server (NTRS)

Wilkie, William K.; Warren, Jerry E.; Horta, Lucas G.; Juang, Jer-Nan; Gibbs, Samuel C.; Dowell, E.; Guerrant, Daniel; Lawrence Dale

2014-01-01

Results from recent National Aeronautics and Space Administration (NASA) research on the structural dynamics and control characteristics of heliogyro solar sails are summarized. Specific areas under investigation include coupled nonlinear finite element analysis of heliogyro membrane blade with solar radiation pressure effects, system identification of spinning membrane structures, solarelastic stability analysis of heliogyro solar sails, including stability during blade deployment, and results from small-scale in vacuo dynamics experiments with spinning high-aspect ratio membranes. A low-cost, rideshare payload heliogyro technology demonstration mission concept, used as a mission context for these heliogyro structural dynamics and solarelasticity investigations, is also described.

Coherent Raman spectroscopy for supersonic flow measurments

NASA Technical Reports Server (NTRS)

She, C. Y.

1986-01-01

In collaboration with NASA/Langley Research Center, a truly nonintrusive and nonseeding method for measuring supersonic molecular flow parameters was proposed and developed at Colorado State University. The feasibility of this Raman Doppler Velocimetry (RDV), currently operated in a scanning mode, was demonstrated not only in a laboratory environment at Colorado State University, but also in a major wind tunnel at NASA/Langley Research Center. The research progress of the RDV development is summarized. In addition, methods of coherent Rayleigh-Brillouin spectroscopy and single-pulse coherent Raman spectroscopy are investigated, respectively, for measurements of high-pressure and turbulent flows.

Fault Diagnostics and Prognostics for Large Segmented SRMs

NASA Technical Reports Server (NTRS)

Luchinsky, Dmitry; Osipov, Viatcheslav V.; Smelyanskiy, Vadim N.; Timucin, Dogan A.; Uckun, Serdar; Hayashida, Ben; Watson, Michael; McMillin, Joshua; Shook, David; Johnson, Mont;

Chronic heat improves mechanical and metabolic response of trained rat heart on ischemia and reperfusion.

PubMed

Levy, E; Hasin, Y; Navon, G; Horowitz, M

1997-05-01

Cardiac mechanics and metabolic performance were studied in isolated perfused hearts of rats subjected to a combined chronic stress of heat acclimation and swimming training (EXAC) or swimming training alone (EX). Diastolic (DP) and systolic pressures (SP), coronary flow (CF), and oxygen consumption were measured during normoperfusion (80 mmHg), and the appearance of ischemic contracture (IC), DP, and SP were measured during progressive graded ischemia, total ischemia (TI), and reperfusion insults. ATP, phosphocreatine, and intracellular pH were measured during TI and reperfusion with 31P nuclear magnetic resonance spectroscopy. During normoperfusion, SP and cardiac efficiency (derived from rate-pressure product-oxygen consumption relationships) were the highest in the 2-mo EXAC hearts (P < 0.0001). During progressive graded ischemia, the development of IC (percentage of total hearts) was similar in both EXAC and EX hearts; the only significant difference was confined to the 1- vs. 2-mo groups. The onset of IC was delayed in the EXAC hearts and, on reperfusion, recovery, particularly of DP, was significantly improved in the latter. After TI, EXAC hearts retained 30% of the ATP pool and there was a delayed decline in intracellular pH. On reperfusion, these hearts also displayed improved ATP and phosphocreatine recovery, the 2-mo EXAC heart demonstrating significantly faster high-energy phosphate salvage, improved diastolic function, and pulse pressure recovery. The data attest to the beneficial effects of heat acclimation on cardiac mechanics of trained rats during normoperfusion and cardiac protection on ischemia and reperfusion. Possibly, energy sparing, lesser acidosis, and shorter duration of IC on ischemia and improved energy salvage on reperfusion contribute synergistically to this potent beneficial effect.

Functional and geometrical interference and interdependency between the right and left ventricle in cor pulmonale: an experimental study on simultaneous measurement of biventricular geometry of acute right ventricular pressure overload.

PubMed

Yamashita, H; Onodera, S; Imamoto, T; Obara, A; Tanazawa, S; Takashio, T; Morimoto, H; Inoue, H

1989-10-01

To clarify the effects of right ventricular (RV) pressure overload on functional and geometrical interference and interdependency between the right and left ventricle, both ventricular internal diameters were measured by the microcrystal technique during lycopodium induced pulmonary embolization in the dog. By repeated embolization, RV systolic pressure was increased progressively until it reached a peak value of about 60-70 mmHg, then it began to fall. At the same time, the hemodynamics deteriorated progressively resulting in death. During the experiment, gradual leftward displacement of the interventricular septum (IVS) without any change in left ventricular (LV) free wall geometry was observed. In pulmonary embolic shock, which showed a fall in LV pressure to about 60 mmHg and cardiac output to about 40% of control, the leftward displacement of IVS became marked, and the cooperative movement of IVS to LV contraction disappeared. The IVS position during acute RV pressure overload was able to account for the transseptal pressure gradient. The importance of IVS position and motion in cardiac function during acute RV pressure overload was stressed. Furthermore, to establish the theoretical treatment in acute cardiopulmonary resuscitation, ligation of the descending aorta (AoL) or norepinephrine ("N") or isoproterenol ("I") administration were examined in a canine pulmonary embolic shock model. AoL or "N" improved the deteriorated hemodynamics with restoration of biventricular geometry. However, "I" did not restore the biventricular geometry despite the transiently improved hemodynamics, and the experimental animals were unable to survive. These results suggest the importance of the maintainance of systemic pressure for the restoration of failed RV function. Further integrated studies are required to understand biventricular interference and interdependency.

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).

Adequate (or Adipose?) Yearly Progress: Assessing the Effect of "No Child Left Behind" on Children's Obesity. NBER Working Paper No. 16873

ERIC Educational Resources Information Center

Anderson, Patricia M.; Butcher, Kristin F.; Schanzenbach, Diane Whitmore

2011-01-01

This paper investigates how accountability pressures under No Child Left Behind (NCLB) may affect children's rate of overweight. Schools facing increased pressures to produce academic outcomes may reallocate their efforts in ways that have unintended consequences for children's health. For example, schools may cut back on recess and physical…

DETERMINATION OF THE SPEED OF SOUND ALONG THE HUGONIOT IN A SHOCKED MATERIAL

DTIC Science & Technology

2017-04-25

correctly predict higher speeds of sound for the higher energy shocked states. The approximations of higher shock pressures diverge progressively...List 11 FIGURES 1 Copper Hugoniot pressure-specific volume plane 4 2 Copper Hugoniot energy -specific volume plane 4 3 Comparison between rate of...volume and energy are being used. = (, ) Then by the chain rule: = | + | Dividing by dv

Flexible and Stretchable Physical Sensor Integrated Platforms for Wearable Human-Activity Monitoringand Personal Healthcare.

PubMed

Trung, Tran Quang; Lee, Nae-Eung

2016-06-01

Flexible and stretchable physical sensors that can measure and quantify electrical signals generated by human activities are attracting a great deal of attention as they have unique characteristics, such as ultrathinness, low modulus, light weight, high flexibility, and stretchability. These flexible and stretchable physical sensors conformally attached on the surface of organs or skin can provide a new opportunity for human-activity monitoring and personal healthcare. Consequently, in recent years there has been considerable research effort devoted to the development of flexible and stretchable physical sensors to fulfill the requirements of future technology, and much progress has been achieved. Here, the most recent developments of flexible and stretchable physical sensors are described, including temperature, pressure, and strain sensors, and flexible and stretchable sensor-integrated platforms. The latest successful examples of flexible and stretchable physical sensors for the detection of temperature, pressure, and strain, as well as their novel structures, technological innovations, and challenges, are reviewed first. In the next section, recent progress regarding sensor-integrated wearable platforms is overviewed in detail. Some of the latest achievements regarding self-powered sensor-integrated wearable platform technologies are also reviewed. Further research direction and challenges are also proposed to develop a fully sensor-integrated wearable platform for monitoring human activity and personal healthcare in the near future. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Thermal barrier coating life-prediction model development

NASA Technical Reports Server (NTRS)

Strangman, T. E.; Neumann, J.; Liu, A.

1986-01-01

The program focuses on predicting the lives of two types of strain-tolerant and oxidation-resistant thermal barrier coating (TBC) systems that are produced by commercial coating suppliers to the gas turbine industry. The plasma-sprayed TBC system, composed of a low-pressure plasma-spray (LPPS) or an argon shrouded plasma-spray (ASPS) applied oxidation resistant NiCrAlY or (CoNiCrAlY) bond coating and an air-plasma-sprayed yttria partially stabilized zirconia insulative layer, is applied by both Chromalloy, Klock, and Union Carbide. The second type of TBS is applied by the electron beam-physical vapor deposition (EB-PVD) process by Temescal. The second year of the program was focused on specimen procurement, TMC system characterization, nondestructive evaluation methods, life prediction model development, and TFE731 engine testing of thermal barrier coated blades. Materials testing is approaching completion. Thermomechanical characterization of the TBC systems, with toughness, and spalling strain tests, was completed. Thermochemical testing is approximately two-thirds complete. Preliminary materials life models for the bond coating oxidation and zirconia sintering failure modes were developed. Integration of these life models with airfoil component analysis methods is in progress. Testing of high pressure turbine blades coated with the program TBS systems is in progress in a TFE731 turbofan engine. Eddy current technology feasibility was established with respect to nondestructively measuring zirconia layer thickness of a TBC system.

Effects of bisoprolol and losartan treatment in the hypertrophic and failing right heart.

PubMed

Andersen, Stine; Schultz, Jacob Gammelgaard; Andersen, Asger; Ringgaard, Steffen; Nielsen, Jan M; Holmboe, Sarah; Vildbrad, Mads D; de Man, Frances S; Bogaard, Harm J; Vonk-Noordegraaf, Anton; Nielsen-Kudsk, Jens Erik

2014-11-01

Sympathetic adrenergic stimulation and the renin-angiotensin-aldosterone system are highly elevated in right heart failure. We evaluated if treatment with the adrenergic receptor blocker bisoprolol or the angiotensin II receptor blocker losartan could prevent the progression of right ventricular (RV) hypertrophy and failure in rats after pulmonary trunk banding (PTB). Male Wistar rats were randomized to severe PTB with a 0.5-mm banding clip (PTB0.5, n = 29), moderate PTB with a 0.6-mm banding clip (PTB0.6, n = 28), or sham operation (SHAM, n = 13). The PTB0.5 and PTB0.6 rats were randomized to 6 weeks of 10 mg/kg/d bisoprolol treatment, 20 mg/kg/d losartan treatment, or vehicle treatment. The PTB caused hypertrophy, dilation, and reduced function of the RV in all rats subjected to the procedure. Rats subjected to the more severe banding developed decompensated RV failure with extracardiac manifestations. Treatment with bisoprolol slowed the heart rate, and treatment with losartan lowered mean arterial pressure, confirming adequate dosing, but none of the treatments improved RV function or arrested the progression of RV hypertrophy and failure compared with vehicle. In our PTB model of pressure overload-induced RV hypertrophy and failure, treatment with bisoprolol and losartan did not demonstrate any beneficial effects in compensated or decompensated RV failure. Copyright © 2014 Elsevier Inc. All rights reserved.

miR-21 is associated with fibrosis and right ventricular failure

PubMed Central

Hu, Dong-Qing; Zhao, Mingming; Blay, Eddie; Sandeep, Nefthi; Ong, Sang-Ging; Jung, Gwanghyun; Kooiker, Kristina B.; Coronado, Michael; Fajardo, Giovanni; Bernstein, Daniel

2017-01-01

Combined pulmonary insufficiency (PI) and stenosis (PS) is a common long-term sequela after repair of many forms of congenital heart disease, causing progressive right ventricular (RV) dilation and failure. Little is known of the mechanisms underlying this combination of preload and afterload stressors. We developed a murine model of PI and PS (PI+PS) to identify clinically relevant pathways and biomarkers of disease progression. Diastolic dysfunction was induced (restrictive RV filling, elevated RV end-diastolic pressures) at 1 month after generation of PI+PS and progressed to systolic dysfunction (decreased RV shortening) by 3 months. RV fibrosis progressed from 1 month (4.4% ± 0.4%) to 3 months (9.2% ± 1%), along with TGF-β signaling and tissue expression of profibrotic miR-21. Although plasma miR-21 was upregulated with diastolic dysfunction, it was downregulated with the onset of systolic dysfunction), correlating with RV fibrosis. Plasma miR-21 in children with PI+PS followed a similar pattern. A model of combined RV volume and pressure overload recapitulates the evolution of RV failure unique to patients with prior RV outflow tract surgery. This progression was characterized by enhanced TGF-β and miR-21 signaling. miR-21 may serve as a plasma biomarker of RV failure, with decreased expression heralding the need for valve replacement. PMID:28469078

Development and Applications Of Photosensitive Device Systems To Studies Of Biological And Organic Materials

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

Gruner, Sol

2012-01-20

The primary focus of the grant is the development of new x-ray detectors for biological and materials work at synchrotron sources, especially Pixel Array Detectors (PADs), and the training of students via research applications to problems in biophysics and materials science using novel x-ray methods. This Final Progress Report provides a high-level overview of the most important accomplishments. These major areas of accomplishment include: (1) Development and application of x-ray Pixel Array Detectors; (2) Development and application of methods of high pressure x-ray crystallography as applied to proteins; (3) Studies on the synthesis and structure of novel mesophase materials derivedmore » from block co-polymers.« less

High-Definition Differential Ion Mobility Spectrometry with Resolving Power up to 500

PubMed Central

Shvartsburg, Alexandre A.; Seim, Tom A.; Danielson, William F.; Norheim, Randy; Moore, Ronald J.; Anderson, Gordon A.; Smith, Richard D.

2013-01-01

As the resolution of analytical methods improves, further progress tends to be increasingly limited by instrumental parameter instabilities that could be ignored before. This is now the case with differential ion mobility spectrometry (FAIMS), where fluctuations of the voltages and gas pressure have become critical. A new high-definition generator for FAIMS compensation voltage reported here provides a stable and accurate output than can be scanned with negligible steps. This reduces the spectral drift and peak width, thus improving the resolving power (R) and resolution. The gain for multiply-charged peptides that have narrowest peaks is up to ~40%, and R ~ 400 – 500 is achievable using He/N2 or H2/N2 gas mixtures. PMID:23345059

Current status of ceramic-based membranes for oxygen separation from air.

PubMed

Hashim, Salwa Meredith; Mohamed, Abdul Rahman; Bhatia, Subhash

2010-10-15

There has been tremendous progress in membrane technology for gas separation, in particular oxygen separation from air in the last 20 years. It provides an alternative route to the existing conventional separation processes such as cryogenic distillation and pressure swing adsorption as well as cheaper production of oxygen with high purity. This review presents the recent advances of ceramic membranes for the separation of oxygen from air at high temperature. It covers the issues and problems with respect to the selectivity and separation performance. The paper also presents different approaches applied to overcome these challenges. The future directions of ceramic-based membranes for oxygen separation from air are also presented. Copyright © 2010 Elsevier B.V. All rights reserved.

Respiratory Support in Bronchiolitis: Trial Evidence.

PubMed

Cunningham, Steve

2018-05-01

Acute viral lower respiratory tract infection is frequently associated with hypoxemia and respiratory distress, sometimes progressing to hypercarbia and respiratory failure. In recent years, trials have assessed the effects of oxygen supplementation and respiratory support with high-flow oxygen therapy. An oxygen saturation target of 90% is as safe and clinically effective as 94% in infants with bronchiolitis. Trials of high-flow humidified oxygen have demonstrated safety, but as yet poorly demarcated an appropriate place for use within the clinical course of the disease. Effective trials of continuous positive airway pressure are lacking and urgently required. The trials reported to date have highlighted the need for common outcomes in relation to treatment failure. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

High-Definition Differential Ion Mobility Spectrometry with Resolving Power up to 500

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

Shvartsburg, Alexandre A.; Seim, Thomas A.; Danielson, William F.

2013-01-20

As the resolution of analytical methods improve, further progress tends to be increasingly limited by instrumental parameter instabilities that could be ignored before. This is now the case with differential ion mobility spectrometry (FAIMS), where fluctuations of the voltages and gas pressure have become critical. A new high-definition generator for FAIMS compensation voltage reported here provides a stable and accurate output than can be scanned with negligible steps. This reduces the spectral drift and peak width, thus improving the resolving power (R) and resolution. The gain for multiply-charged peptides that have narrowest peaks is up to ~40%, and R ~more » 400 - 500 is achievable using He/N2 or H2/N2 gas mixtures.« less

Buoyancy and Pressure Effects on Bulk Metal-Oxygen Reactions

NASA Technical Reports Server (NTRS)

Abbud-Madrid, A.; McKnight, C.; Branch, M. C.; Daily, J. W.; Friedman, R. (Technical Monitor)

1998-01-01

The combustion behavior of metal-oxygen reactions if a weakly buoyant environment is studied to understand the rate-controlling mechanisms in the homogeneous and heterogeneous combustion of bulk metals. Cylindrical titanium and magnesium specimens are ignited in pure-oxygen at pressures ranging from 0.1 to 4.0 atm. Reduced gravity is obtained from an aircraft flying parabolic trajectories. A weakly buoyant environment is generated at low pressures under normal gravity and also at 1 atm under reduced gravity (0.01g). The similarity between these two experimental conditions comes from the p(exp 2)g buoyancy scale extracted from the Grashof number. Lower propagation rates of the molten interface on titanium samples are found at progressively lower pressures at 1 g. These rates are compared to theoretical results from heat conduction analyses with a diffusion/convection controlled reaction. The close agreement found between experimental and theoretical values indicate the importance values indicate the importance of natural convection enhanced oxygen transport on combustion rates. For magnesium, progressively longer burning times are experienced at lower pressures and 1 g. Under reduced gravity conditions at 1 atm, a burning time twice as long as in 1 g is exhibited. However, in this case, the validity of the p(exp 2)g buoyancy scale remains untested due to the inability to obtain steady gas-phase burning of the magnesium sample at 0.1 atm. Nevertheless, longer burning times and larger flame standoff distance at low pressures and at low gravity points to a diffusion/convection controlled reaction.

[The clinical significance of microcirculation and oxygen metabolism evaluation in acute kidney injury assessment in patients with septic shock after resuscitation].

PubMed

Yu, C; Liu, D W; Wang, X T; He, H W; Pan, P; Xing, Z Q

2018-02-01

Objective: To evaluate the value of microcirculation and oxygen metabolism evaluation (MicrOME) in acute kidney injury(AKI) evaluation in patients with septic shock after resuscitation. Methods: Consecutive patients with septic shock after resuscitation and mechanical ventilation were enrolled from October 2016 to February 2017 in ICU at Peking Union Medical College Hospital.Patients were divided into 3 groups based on 10 min transcutaneous oxygen challenge test transcutaneous partial pressure of oxygen(PtcO(2))and venoarterial pressure of carbon dioxide difference (Pv-aCO(2)) /arteriovenous O(2) content difference (Ca-vO(2)) by blood gas analysis, i.e. group A [ΔPtcO(2)>66 mmHg(1 mmHg=0.133 kPa) and Pv-aCO(2)/Ca-vO(2)≤1.23], group B (ΔPtcO(2)≤66 mmHg), group C (ΔPtcO(2)>66 mmHg and Pv-aCO(2)/Ca-vO(2)>1.23). Heart rate,mean arterial pressure,central venous pressure,noradrenaline dose,lactate,Pv-aCO(2),Ca-vO(2), lactate clearance, central venous oxygen saturation(ScvO(2)) and liquid equilibrium were assessed after resuscitation.AKI staging based on Kidney Disease Global Improving Outcomes (KDIGO) clinical practice guideline was analyzed. The predictive value of lactate, ScvO(2), Pv-aCO(2)/Ca-vO(2) to progression of AKI after resuscitation was determined using receiver operating characteristic(ROC)curve analysis. Results: A total of 49 septic shock patients were enrolled including 30 males and 19 females with mean age of (61.10±17.10)years old.There were 19 patients in group A,21 patients in group B, and 9 patients in group C. Acute physiology and chronic health evaluation Ⅱ score was 20.92±7.19 and sequential organ failure assessment score 12.02±3.28. There were 4 patients with AKI and 1 progressed in group A, 11 patients with AKI and 2 progressed in group B, 6 patients with AKI and 4 progressed in group C. The cutoff value of Pv-aCO(2)/Ca-vO(2) was equal or more than 2.20 for predicting progression of AKI, resulting in a sensitivity of 85.7% and a specificity of 73.8%. Conclusion: MicrOME is a significant parameter to predict the progression of AKI in patients with septic shock after resuscitation. Pv-aCO(2)/Ca-vO(2) is also a good predictive factor.

Environmental Factors and Myopia: Paradoxes and Prospects for Prevention.

PubMed

Rose, Kathryn Ailsa; French, Amanda Nicole; Morgan, Ian George

The prevalence of myopia in developed countries in East and Southeast Asia has increased to more than 80% in children completing schooling, whereas that of high myopia has increased to 10%-20%. This poses significant challenges for correction of refractive errors and the management of pathological high myopia. Prevention is therefore an important priority. Myopia is etiologically heterogeneous, with a low level of myopia of clearly genetic origins that appears without exposure to risk factors. The big increases have occurred in school myopia, driven by increasing educational pressures in combination with limited amounts of time spent outdoors. The rise in prevalence of high myopia has an unusual pattern of development, with increases in prevalence first appearing at approximately age 11. This pattern suggests that the increasing prevalence of high myopia is because of progression of myopia in children who became myopic at approximately age 6 or 7 because age-specific progression rates typical of East Asia will take these children to the threshold for high myopia in 5 to 6 years. This high myopia seems to be acquired, having an association with educational parameters, whereas high myopia in previous generations tended to be genetic in origin. Increased time outdoors can counter the effects of increased nearwork and reduce the impact of parental myopia, reducing the onset of myopia, and this approach has been validated in 3 randomized controlled trials. Other proposed risk factors need further work to demonstrate that they are independent and can be modified to reduce the onset of myopia.

Numerical analysis of rotating stall instabilities of a pump- turbine in pump mode

NASA Astrophysics Data System (ADS)

Xia, L. S.; Cheng, Y. G.; Zhang, X. X.; Yang, J. D.

2014-03-01

Rotating stall may occur at part load flow of a pump-turbine in pump mode. Unstable flow structures developing under stall condition can lead to a sudden drop of efficiency, high dynamic load and even cavitation. CFD simulations on a pump-turbine model in pump mode were carried out to reveal the onset and developed mechanisms of these unstable flow phenomena at part load. The simulation results of energy-discharge and efficiency characteristics are in good agreement with those obtained by experiments. The more deviate from design conditions with decreasing flow rate, the more flow separations within the vanes. Under specific conditions, four stationary separation zones begin to progress on the circumference, rotating at a fraction of the impeller rotation rate. Rotating stalls lead to the flow in the vane diffuser channels alternating between outward jet flow and blockage. Strong jets impact the spiral casing wall causing high pressure pulsations. Severe separations of the stall cells disturb the flow inducing periodical large amplitude pressure fluctuations, of which the intensity at different span wise of the guide vanes is different. The enforced rotating nonuniform pressure distributions on the circumference lead to dynamic uniform forces on the impeller and guide vanes. The results show that the CFD simulations are capable to gain the complicated flow structure information for analysing the unstable characteristics of the pump mode at part load.

Autoxidation as a source of gas-phase highly-oxidized multifunctional compounds (HOM) - measured by chemical ionization spectrometry (CIMS) utilizing various reagent ion chemistries

NASA Astrophysics Data System (ADS)

Rissanen, M.; Kurten, T.; Mauldin, L.; Ehn, M.

2017-12-01

Secondary organic aerosol (SOA) constitutes the largest fraction of atmospheric submicron particulate matter. Despite its importance to the Earth's radiative balance, mainly by acting as a source of cloud condensation nuclei (CCN), the molecular details of the first-steps of atmospheric new particle formation keep eluding researchers. Recently a gas-phase autocatalytic oxidation mechanism (=autoxidation) was invoked to explain the very fast formation of highly-oxidized multifunctional organic compounds (HOMs), and it was shown to provide the needed prompt condensable matter that forms the smallest of the atmospheric particles. Of detailed autoxidation progressions, only cyclohexene ozonolysis initiated oxidation has been described by quantum chemical computations, and it was quickly recognized that further reaction steps are needed (such as endoperoxidation) to explain the formation of the observed HOM products from biogenic terpenes. Also it was realized that the simplest group additivity principles commonly applied to derive saturation vapor pressures do not suffice to determine the vapor pressures of multiple hydroperoxide and other oxidized functionalities containing HOM products. Thereby the fraction of the lowest volatility products is less than previously assumed, which could indicate reactive uptake of HOM products. In the AGU fall meeting I will present our most recent findings on resolving the (i) detailed molecular mechanisms generating HOMs, (ii) their actual vapor pressures, and (iii) their interaction with the environment.

Asymptomatic Wolff-Parkinson-White Pattern ECG in USAF Aviators.

PubMed

Davenport, Eddie D; Rupp, Karen A N; Palileo, Edwin; Haynes, Jared

2017-01-01

Wolff-Parkinson-White (WPW) pattern is occasionally found in asymptomatic aviators during routine ECGs. Aeromedical concerns regarding WPW pattern include risk of dysrhythmia or sudden cardiac death (SCD), thus affecting the safety of flight. The purpose of this study was to determine the prevalence and outcomes of aviators with asymptomatic WPW pattern and assess for risk factors that contribute to progression to dysrhythmia or symptoms. The U.S. Air Force (USAF) ECG library database containing over 1.2 million ECGs collected over the past 68 yr was used to identify 638 individual aviators with WPW pattern. Demographic, medical history, and outcome data were obtained by medical record review. Aviators who developed high risk features defined as symptoms, arrhythmia, or ablation of a high risk pathway, were compared to those who remained asymptomatic. Prevalence of WPW pattern was 0.30% among all USAF aviators. Of the 638 individuals, 64 (10%) progressed to the combined endpoint of SCD, arrhythmia, and/or ablation of a high risk pathway over 6868 patient years, with average follow-up of 10.5 yr. There were two sudden cardiac deaths (0.3%). Annual risk of possible sudden incapacitation was 0.95% and of SCD 0.03%. Those that progressed to high risk were significantly younger, had lower diastolic blood pressure, lower total cholesterol, and better physical fitness testing scores. WPW pattern on ECG found in asymptomatic aviators confers < 1% annual risk of arrhythmia or incapacitating events with the highest risk in the younger, healthier, and most fit populations.Davenport ED, Rupp KAN, Palileo E, Haynes J. Asymptomatic Wolff-Parkinson-White pattern ECG in USAF aviators. Aerosp Med Hum Perform. 2017; 88(1):56-60.

Blood pressure, magnesium and other mineral balance in two rat models of salt-sensitive, induced hypertension: effects of a non-peptide angiotensin II receptor type 1 antagonist.

PubMed

Rondón, Lusliany Josefina; Marcano, Eunice; Rodríguez, Fátima; del Castillo, Jesús Rafael

2014-01-01

The renin-angiotensin system is critically involved in regulating arterial blood pressure (BP). Inappropriate angiotensin type-1 receptor activation by angiotensin-II (Ang-II) is related to increased arterial BP. Mg has a role in BP; it can affect cardiac electrical activity, myocardial contractility, and vascular tone. To evaluate the relationship between high BP induced by a high sodium (Na) diet and Mg, and other mineral balances, two experimental rat models of salt-sensitive, induced-hypertension were used: Ang-II infused and Dahl salt-sensitive (SS) rats. We found that: 1) Ang-II infusion progressively increased BP, which was accompanied by hypomagnesuria and signs of secondary hyperaldosteronism; 2) an additive effect between Ang-II and a high Na load may have an effect on strontium (Sr), zinc (Zn) and copper (Cu) balances; 3) Dahl SS rats fed a high Na diet had a slow pressor response, accompanied by altered Mg, Na, potassium (K), and phosphate (P) balances; and 4) losartan prevented BP increases induced by Ang II-NaCl, but did not modify mineral balances. In Dahl SS rats, losartan attenuated high BP and ameliorated magnesemia, Na and K balances. Mg metabolism maybe considered a possible defect in this strain of rat that may contribute to hypertension.

Clinical utility of metabolic syndrome severity scores: considerations for practitioners

PubMed Central

DeBoer, Mark D; Gurka, Matthew J

2017-01-01

The metabolic syndrome (MetS) is marked by abnormalities in central obesity, high blood pressure, high triglycerides, low high-density lipoprotein-cholesterol, and high fasting glucose and appears to be produced by underlying processes of inflammation, oxidative stress, and adipocyte dysfunction. MetS has traditionally been classified based on dichotomous criteria that deny that MetS-related risk likely exists as a spectrum. Continuous MetS scores provide a way to track MetS-related risk over time. We generated MetS severity scores that are sex- and race/ethnicity-specific, acknowledging that the way MetS is manifested may be different by sex and racial/ethnic subgroup. These scores are correlated with long-term risk for type 2 diabetes mellitus and cardiovascular disease. Clinical use of scores like these provide a potential opportunity to identify patients at highest risk, motivate patients toward lifestyle change, and follow treatment progress over time. PMID:28255250