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Daniel Levy - One of the best experts on this subject based on the ideXlab platform.
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cross classification of jnc vi blood Pressure Stages and risk groups in the framingham heart study
JAMA Internal Medicine, 1999Co-Authors: Donald M Lloydjones, Jane C Evans, Martin G Larson, Christopher J Odonnell, Peter W F Wilson, Daniel LevyAbstract:Background The recently published Sixth Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC VI) includes a classification of blood Pressure Stages and a new risk stratification component. Patients with high-normal blood Pressure or hypertension are stratified into risk group A (no associated cardiovascular disease risk factors, no target organ damage or cardiovascular disease); group B (≥1 associated cardiovascular disease risk factor excluding diabetes, no target organ damage or cardiovascular disease); or group C (diabetes or target organ damage or cardiovascular disease). Objective To examine the prevalence of risk groups and blood Pressure Stages in a community-based sample. Methods We evaluated 4962 subjects from the Framingham Heart Study and Framingham Offspring Study examined between 1990 and 1995. We cross-classified men and women separately according to their JNC VI blood Pressure Stages and risk groups. Results In the whole sample, 43.7% had optimal or normal blood Pressure and 13.4% had high-normal blood Pressure; 12.9% had Stage 1 hypertension and 30.0% had Stage 2 or greater hypertension or were receiving medication. As blood Pressure Stage increased, the proportion of subjects in group A decreased, whereas the proportion in group C increased. Among those with high-normal blood Pressure or hypertension, only 2.4% (all women) were in risk group A, 59.3% were in group B, and 38.2% were in group C. In the high-normal or hypertensive group, 39.4% qualified for lifestyle modification as the initial intervention according to JNC VI recommendations, whereas 60.6% were eligible for initial drug therapy or were already receiving drug therapy. Nearly one third of high-normal subjects were in risk group C, in which early drug therapy may be needed. Among those in Stage 1, only 4.0% were in group A, in which prolonged lifestyle modification is recommended. Conclusions These results provide a foundation for estimating the number of individuals with hypertension who fall into different risk groups that require different treatment approaches. With nearly 50 million individuals with hypertension in the United States, there are important implications for clinicians and policymakers if JNC VI recommendations are widely adopted in clinical practice.
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differential impact of systolic and diastolic blood Pressure level on jnc vi staging
Hypertension, 1999Co-Authors: Donald M Lloydjones, Jane C Evans, Marti G Larso, Christophe J Odonnell, Daniel LevyAbstract:The sixth Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure classifies blood Pressure into Stages on the basis of both systolic (SBP) and diastolic (DBP) blood Pressure levels. When a disparity exists between SBP and DBP Stages, patients are classified into the higher Stage ("up-Staged"). We evaluated the effect of disparate levels of SBP and DBP on blood Pressure staging and eligibility for therapy. We examined 4962 Framingham Heart Study subjects between 1990 and 1995 and determined blood Pressure Stages on the basis of SBP alone, DBP alone, or both. After the exclusion of subjects on antihypertensive therapy (n=1306), 3656 subjects (mean age 58+/-13 years; 55% women) were eligible. In this sample, 64.6% of subjects had congruent Stages of SBP and DBP, 31.6% were up-Staged on the basis of SBP, and 3.8% on the basis of DBP; thus, SBP alone correctly classified JNC-VI Stage in approximately 96% (64.6%+31.6%) of the subjects. Among subjects >60 years of age, SBP alone correctly classified 99% of subjects; in those Pressure or hypertension, who were potentially eligible for drug therapy, 13.0% had congruent elevations of SBP and DBP, 77.7% were up-Staged on the basis of SBP, and 9.3% were up-Staged on the basis of DBP; SBP alone correctly classified 91%, whereas DBP alone correctly classified only 22%. SBP elevation out of proportion to DBP is common in middle-aged and older persons. SBP appears to play a greater role in the determination of JNC-VI blood Pressure Stage and eligibility for therapy. Given these results, combined with evidence from hypertension treatment trials, future guidelines might consider a greater role for SBP than for DBP in determining the presence of hypertension, risk of cardiovascular events, eligibility for therapy, and benefits of treatment.
C. De Capitani - One of the best experts on this subject based on the ideXlab platform.
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Phase Relations and Chemical Composition of Phengite and Paragonite in Pelitic Schists During Decompression: a Case Study from the Monte Rosa Nappe and Camughera- Moncucco Unit, Western Alps
Journal of Petrology, 2005Co-Authors: Lukas M. Keller, Rainer Abart, Stefan M. Schmid, C. De CapitaniAbstract:The metamorphic evolution of metapelites from the eastern part of the Monte Rosa nappe and the Camughera–Moncucco unit, both situated in the upper Penninic units SW of the Simplon line, were investigated using microstructural relationships and equilibrium phase diagrams. The units under consideration experienced preAlpine amphibolite-facies conditions and underwent a complex metamorphic evolution during the Alpine orogeny. Peak Pressures during an early Alpine high-Pressure Stage of 12� 5–16 kbar were similar in the Monte Rosa nappe and Camughera–Moncucco unit. A pronounced thermal gradient is indicated during decompression leading to an amphibolite-facies overprint, as the decompression paths went through the chlorite, biotite and plagioclase stability fields in most of the Monte Rosa nappe, through the staurolite field in the easternmost Monte Rosa nappe and in the Camughera– Moncucco unit, and through the sillimanite field in the easternmost Camughera–Moncucco unit. In high-Al metapelites the initial formation of staurolite is related to continuous paragonite breakdown and associated formation of biotite. In the course of this reaction phengite becomes successively sodium enriched. In low-Al metapelites, in contrast, the initial staurolite formation occurs via the continuous breakdown of sodium-rich phengite. In both low- and high-Al metapelites the largest volume of staurolite is formed during the continuous breakdown of sodium-rich phengite below P–T conditions of about 9� 5 kbar at 600–650 � C. During this reaction phengite becomes successively potassium enriched as sodium from phengite is used to form the albite component in plagioclase. For ‘ normal’ pelitic chemistries, phengite becomes Na enriched during decompression through the breakdown of paragonite along a nearisothermal decompression path. The Na content in phengite reaches its maximum when paragonite is entirely consumed. During further decompression the paragonite component in phengite decreases again because Na is preferentially incorporated into the albite component of plagioclase.
Hyungee Kim - One of the best experts on this subject based on the ideXlab platform.
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dynamic simulation of a triple Pressure combined cycle plant hot start up and shutdown
Fuel, 2016Co-Authors: Nicolas Mertens, Falah Alobaid, Bernd Epple, Thomas Lanz, Hyungee KimAbstract:Abstract The operation of combined-cycle power plants is increasingly determined by frequent start-ups and shutdowns for grid balancing. This study investigates the capability of a comprehensive process simulation model to predict the transient response of a triple-Pressure heat recovery steam generator (HRSG) with reheater to the start-up and shutdown procedures of a heavy-duty gas turbine. The model is based on geometry data, system descriptions and heat transfer calculations established in the original HRSG design. The numerical solution approach and the practical development of a suitable model structure, including the required control circuits, are explained. Detailed simulation results are presented, using initial conditions that correspond to a previous overnight shutdown. Calculations are performed for a complete operating cycle of the plant, where the following main phases are distinguished: start-up procedure, load-following operation, design operation and shutdown procedure. The numerical model is validated with measurement data of the commercial power plant for each Pressure Stage, yielding good agreement. Deviation from the transient behaviour of the real plant is discussed with regard to modelling assumptions and incomplete information on components outside the HRSG system boundaries.
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a comparative study of different dynamic process simulation codes for combined cycle power plants part a part loads and off design operation
Fuel, 2015Co-Authors: Falah Alobaid, Karl Karner, Bernd Epple, Ralf Starkloff, Stefan Pfeiffer, Hyungee KimAbstract:Abstract In part A of this study, investigations into the capability of different process simulation codes to predict the real behaviour of a combined cycle power plant during part loads and off-design operation are carried out. The combined cycle power plant with a sub-critical three-Pressure-Stage heat recovery steam generator is built using the process simulation software tools Aspen Plus Dynamics and Apros. The generated numerical models are validated against the measurements at different steady-state operation points, namely 100%, 80% and 60% loads. The numerical results obtained display a very good agreement towards the given data with a maximal relative error of about 5% for the Pressure and less than 1% for the temperature and the mass flow rate. Furthermore, the validated models are also evaluated against the dynamic measurements during a transient operation for a time period of 400 min. Apros and Aspen Plus Dynamics models predict qualitatively the right developments of the plant parameters. However, the simulated results deviate quantitatively from the experimental data with a maximum relative error of about 10%. It can be concluded that the dynamic simulation models can represent accurately the real combined cycle power plant at different steady-state loads, while they can capture the plant behaviour during the off-design operation with less accuracy.
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numerical and experimental study of a heat recovery steam generator during start up procedure
Energy, 2014Co-Authors: Falah Alobaid, Karl Karner, Joerg Belz, Bernd Epple, Hyungee KimAbstract:The share of renewable energies in electricity and heat supply besides the conventional energy resources gains more importance. Accordingly, the efficiency and flexibility of modern thermal power plants should be further improved. To design such a system, it is necessary to generate detailed computer models that can accurately predict the power plant behaviour during fast transients, part loads and start-up procedures. In this work, a dynamic simulation model for a subcritical three-Pressure-Stage HRSG (heat recovery steam generator) is built, employing the advanced processing simulation software Aspen Plus Dynamics®. The simulation results obtained from the HRSG model are validated towards the dynamic measurements during warm start-up procedure. The capability of processing simulation software used to estimate the dynamic behaviour of real HRSG is demonstrated. The HRSG model shows high accuracy at different part loads with a maximum relative error of about 5%. The good agreement suggests that the HRSG model is very reliable and is capable to predict the operational processes.
Marco Scambelluri - One of the best experts on this subject based on the ideXlab platform.
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Fingerprinting and relocating tectonic slices along the plate interface: Evidence from the Lago Superiore unit at Monviso (Western Alps)
Lithos, 2020Co-Authors: Mattia Gilio, Marco Scambelluri, Marguerite Godard, Samuele Agostini, Thomas Pettke, Philippe Agard, Michele Locatelli, Samuel AngiboustAbstract:The Lago Superiore Unit (LSU, Monviso Massif, Italian Western Alps) is a section of fossil oceanic lithosphere equilibrated to eclogite facies conditions (550 °C – 2.8 GPa) during Alpine subduction (45–40 Ma). It is cut by two major shear zones, namely the Intermediate (ISZ) and Lower Shear Zone (LSZ), mostly consisting of serpentinite. The lowermost, serpentine-rich, section of the Lago Superiore Unit, the Basal Serpentinite, separates the HP ophiolite domain from the underlying continental Dora-Maira Unit. Here we show that the LSZ and the Basal Serpentinite were active at different Stages of the subduction and exhumation history of the complex. Most of retrograde deformation and mineral re-equilibration were localized in the LSZ. Channelized fluids percolating during this phase chemically homogenized the LSZ serpentinites, that preserved their HP mineralogy only locally; the best-preserved relicts of the eclogite-facies high Pressure Stage within the LSZ serpentinite are nodules of magnesite (representing former veins) and eclogite blocks. Differently, the underlying Basal Serpentinite largely escaped the exhumation-related processes and still records the prograde chemical and petrological history of the LSU serpentinite, from ocean-floor hydration to HP metamorphic conditions. The Lago Superiore Unit thus represents a snapshot of major Alpine metamorphic and shearing events, from prograde subduction to exhumation. Its km-scale thickness, and the oriented antigorite fabric in the Lower Shear Zone and Basal Serpentinite makes it a good seismic reflector. This HP ophiolite complex can thus be used as proxy of a deep (70–80 km) Alpine-type subduction zone, and to better constrain and interpret seismic images of present-day convergent margins.
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Redistribution of high-Pressure fluids during retrograde metamorphism of eclogite-facies rocks (Voltri Massif, Italian Western Alps)
Lithos, 1996Co-Authors: F. Vallis, Marco ScambelluriAbstract:Abstract High-Pressure clinopyroxenes in metasomatic mafic rocks (rodingites and metagabbros containing titanoclinohumite) and eclogites from the Voltri Massif (Ligurian Western Alps) retain primary, two-phase aqueous inclusions (H 2 O + NaCl ± KCl). In the metasomatized rocks the inclusions align with the c axes and the cleavage planes of diopside. The eclogites display mylonitic textures: primary fluid inclusions are hosted in early porphyroclasts of omphacite (omphacite I) and are absent in later fine-grained omphacite (omphacite II) that forms the mylonitic foliation. Omphacite I has been frequently replaced by retrograde symplectites (clinopyroxene + plagioclase ± amphibole); in such cases the fluid inclusions are either absent, or occur in much lower number. The textural observations suggest that formation of the symplectites has been controlled by availability of the fluid inclusions inside omphacite I. The symplectites have been in turn overgrown by glaucophanic and winchitic amphiboles, indicating that breakdown of the omphacite I to symplectites still occurred at relatively high-Pressure. Post-entrapment changes have caused a large range of densities in the analyzed inclusions. Although the textural evidence constrains the entrapment of fluid inclusions to high-Pressure conditions, the highest density isochores in the eclogites indicate Pressure-temperature conditions (8 kbar and 550 °C) lower than those attained during the high-Pressure Stage. Such P-T estimates approach those of symplectite formation after omphacite I. Thus, the fluid inclusions preserved in omphacite were formed by low-Pressure re-equilibration of a fluid presumably trapped at eclogite-facies conditions. The inclusions kinetically triggered the retrograde breakdown of the eclogitic clinopyroxenes. The compositional overlap between the analyzed inclusions and those related to the latest (greenschist) evolutionary Stage, suggests further redistribution of the high-Pressure fluids and close-system behaviour of these rocks during their overall exhumation path.
Jane C Evans - One of the best experts on this subject based on the ideXlab platform.
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cross classification of jnc vi blood Pressure Stages and risk groups in the framingham heart study
JAMA Internal Medicine, 1999Co-Authors: Donald M Lloydjones, Jane C Evans, Martin G Larson, Christopher J Odonnell, Peter W F Wilson, Daniel LevyAbstract:Background The recently published Sixth Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC VI) includes a classification of blood Pressure Stages and a new risk stratification component. Patients with high-normal blood Pressure or hypertension are stratified into risk group A (no associated cardiovascular disease risk factors, no target organ damage or cardiovascular disease); group B (≥1 associated cardiovascular disease risk factor excluding diabetes, no target organ damage or cardiovascular disease); or group C (diabetes or target organ damage or cardiovascular disease). Objective To examine the prevalence of risk groups and blood Pressure Stages in a community-based sample. Methods We evaluated 4962 subjects from the Framingham Heart Study and Framingham Offspring Study examined between 1990 and 1995. We cross-classified men and women separately according to their JNC VI blood Pressure Stages and risk groups. Results In the whole sample, 43.7% had optimal or normal blood Pressure and 13.4% had high-normal blood Pressure; 12.9% had Stage 1 hypertension and 30.0% had Stage 2 or greater hypertension or were receiving medication. As blood Pressure Stage increased, the proportion of subjects in group A decreased, whereas the proportion in group C increased. Among those with high-normal blood Pressure or hypertension, only 2.4% (all women) were in risk group A, 59.3% were in group B, and 38.2% were in group C. In the high-normal or hypertensive group, 39.4% qualified for lifestyle modification as the initial intervention according to JNC VI recommendations, whereas 60.6% were eligible for initial drug therapy or were already receiving drug therapy. Nearly one third of high-normal subjects were in risk group C, in which early drug therapy may be needed. Among those in Stage 1, only 4.0% were in group A, in which prolonged lifestyle modification is recommended. Conclusions These results provide a foundation for estimating the number of individuals with hypertension who fall into different risk groups that require different treatment approaches. With nearly 50 million individuals with hypertension in the United States, there are important implications for clinicians and policymakers if JNC VI recommendations are widely adopted in clinical practice.
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differential impact of systolic and diastolic blood Pressure level on jnc vi staging
Hypertension, 1999Co-Authors: Donald M Lloydjones, Jane C Evans, Marti G Larso, Christophe J Odonnell, Daniel LevyAbstract:The sixth Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure classifies blood Pressure into Stages on the basis of both systolic (SBP) and diastolic (DBP) blood Pressure levels. When a disparity exists between SBP and DBP Stages, patients are classified into the higher Stage ("up-Staged"). We evaluated the effect of disparate levels of SBP and DBP on blood Pressure staging and eligibility for therapy. We examined 4962 Framingham Heart Study subjects between 1990 and 1995 and determined blood Pressure Stages on the basis of SBP alone, DBP alone, or both. After the exclusion of subjects on antihypertensive therapy (n=1306), 3656 subjects (mean age 58+/-13 years; 55% women) were eligible. In this sample, 64.6% of subjects had congruent Stages of SBP and DBP, 31.6% were up-Staged on the basis of SBP, and 3.8% on the basis of DBP; thus, SBP alone correctly classified JNC-VI Stage in approximately 96% (64.6%+31.6%) of the subjects. Among subjects >60 years of age, SBP alone correctly classified 99% of subjects; in those Pressure or hypertension, who were potentially eligible for drug therapy, 13.0% had congruent elevations of SBP and DBP, 77.7% were up-Staged on the basis of SBP, and 9.3% were up-Staged on the basis of DBP; SBP alone correctly classified 91%, whereas DBP alone correctly classified only 22%. SBP elevation out of proportion to DBP is common in middle-aged and older persons. SBP appears to play a greater role in the determination of JNC-VI blood Pressure Stage and eligibility for therapy. Given these results, combined with evidence from hypertension treatment trials, future guidelines might consider a greater role for SBP than for DBP in determining the presence of hypertension, risk of cardiovascular events, eligibility for therapy, and benefits of treatment.
