Early improvement in left atrial remodeling and function after mitral valve repair or replacement in organic symptomatic mitral regurgitation assessed by three-dimensional echocardiography.

PubMed

Le Bihan, David C S; Della Togna, Dorival Julio; Barretto, Rodrigo B M; Assef, Jorge Eduardo; Machado, Lúcia Romero; Ramos, Auristela Isabel de Oliveira; Abdulmassih Neto, Camilo; Moisés, Valdir Ambrosio; Sousa, Amanda G M R; Campos, Orlando

2015-07-01

Left atrial (LA) dilation is associated with worse prognosis in various clinical situations including chronic mitral regurgitation (MR). Real time three-dimensional echocardiography (3DE) has allowed a better assessment of LA volumes and function. Little is known about LA size and function in early postoperative period in symptomatic patients with chronic organic MR. We aimed to investigate these aspects. By means of 3DE, 43 patients with symptomatic chronic organic MR were prospectively studied before and 30 days after surgery (repair or bioprosthetic valve replacement). Twenty subjects were studied as controls. Maximum (Vol-max), minimum, and preatrial contraction LA volumes were measured and total, passive, and active LA emptying fractions were calculated. Before surgery patients had higher LA volumes (P < 0.001) but smaller LA emptying fractions than controls (P < 0.01). After surgery there was a reduction in all 3 LA volumes and an increase in active atrial emptying fraction (AAEF). Multivariate analysis showed that independent predictors of early postoperative Vol-max reduction were preoperative diastolic blood pressure (coefficient = -0.004; P = 0.02), lateral mitral annular early diastolic velocity (e') (coefficient = 0.023; P = 0.008), and the mean transmitral diastolic gradient increment (coefficient = -0.035; P < 0.001). Furthermore, e' was also independently associated with AAEF increase (odds ratio = 1.66, P = 0.027). Early LA reverse remodeling and functional improvement occur after successful surgery of symptomatic organic MR regardless of surgical technique. Diastolic blood pressure and transmitral mean gradient augmentation are variables negatively related to Vol-max reduction. Besides, e' is positively correlated with both Vol-max reduction and AAEF increase. © 2014, Wiley Periodicals, Inc.

Left ventricular early diastolic inflow velocity and atrial ventricular plane downward velocity: useful parameters to test diastolic function in clinical practice? Diastolic parameters tested in a clinical setting.

PubMed

Winter, R; Gudmundsson, P; Ericsson, G; Willenheimer, R

2001-06-01

To study the clinical value of the colour-M-mode slope of the early diastolic left ventricular filling phase (Vp) and the early diastolic downward M-mode slope of the left atrioventricular plane displacement (EDS), compared with diastolic function assessed by traditional Doppler evaluation. In 65 consecutive patients EDS and Vp were compared with a four-degree traditional diastolic function classification, based on pulsed Doppler assessment of the early to atrial transmitral flow ratio (E/A), the E-wave deceleration time (Edt), and the systolic to diastolic (S/D) pulmonary venous inflow ratio. Vp (P=0.006) and EDS (P=0.045) were related to traditional diastolic function (Kruskal--Wallis analysis). EDS showed a trend brake between the moderate and severe diastolic dysfunction groups by traditional Doppler evaluation. Vp and EDS correlated weakly in simple linear regression analysis (r=0.33). Vp and EDS discriminated poorly between normal and highly abnormal diastolic function. Vp and EDS were significantly related to diastolic function by traditional Doppler evaluation. They were, however, not useful as single parameters of left ventricular diastolic function due to a small difference between normal and highly abnormal values, allowing for little between-measurement variability. Consequently, these methods for the evaluation of left ventricular diastolic function do not add significantly to traditional Doppler evaluation.

Evidence for persistent flow and aqueous sedimentation on early Mars.

PubMed

Malin, Michael C; Edgett, Kenneth S

2003-12-12

Landforms representative of sedimentary processes and environments that occurred early in martian history have been recognized in Mars Global Surveyor Mars Orbiter Camera and Mars Odyssey Thermal Emission Imaging System images. Evidence of distributary, channelized flow (in particular, flow that lasted long enough to foster meandering) and the resulting deposition of a fan-shaped apron of debris indicate persistent flow conditions and formation of at least some large intracrater layered sedimentary sequences within fluvial, and potentially lacustrine, environments.

Vector flow mapping in obstructive hypertrophic cardiomyopathy to assess the relationship of early systolic left ventricular flow and the mitral valve.

PubMed

Ro, Richard; Halpern, Dan; Sahn, David J; Homel, Peter; Arabadjian, Milla; Lopresto, Charles; Sherrid, Mark V

2014-11-11

The hydrodynamic cause of systolic anterior motion of the mitral valve (SAM) is unresolved. This study hypothesized that echocardiographic vector flow mapping, a new echocardiographic technique, would provide insights into the cause of early SAM in obstructive hypertrophic cardiomyopathy (HCM). We analyzed the spatial relationship of left ventricular (LV) flow and the mitral valve leaflets (MVL) on 3-chamber vector flow mapping frames, and performed mitral valve measurements on 2-dimensional frames in patients with obstructive and nonobstructive HCM and in normal patients. We compared 82 patients (22 obstructive HCM, 23 nonobstructive HCM, and 37 normal) by measuring 164 LV pre- and post-SAM velocity vector flow maps, 82 maximum isovolumic vortices, and 328 2-dimensional frames. We observed color flow and velocity vector flow posterior to the MVL impacting them in the early systolic frames of 95% of obstructive HCM, 22% of nonobstructive HCM, and 11% of normal patients (p < 0.001). In both pre- and post-SAM frames, we measured a high angle of attack >60° of local vector flow onto the posterior surface of the leaflets whether the flow was ejection (59%) or the early systolic isovolumic vortex (41%). Ricochet of vector flow, rebounding off the leaflet into the cul-de-sac, was noted in 82% of the obstructed HCM, 9% of nonobstructive HCM, and none (0%) of the control patients (p < 0.001). Flow velocities in the LV outflow tract on the pre-SAM frame 1 and 2 mm from the tip of the anterior leaflet were low: 39 and 43 cm/s, respectively. Early systolic flow impacts the posterior surfaces of protruding MVL initiating SAM in obstructive HCM. Copyright © 2014 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Rainfall threshold calculation for debris flow early warning in areas with scarcity of data

NASA Astrophysics Data System (ADS)

Pan, Hua-Li; Jiang, Yuan-Jun; Wang, Jun; Ou, Guo-Qiang

2018-05-01

Debris flows are natural disasters that frequently occur in mountainous areas, usually accompanied by serious loss of lives and properties. One of the most commonly used approaches to mitigate the risk associated with debris flows is the implementation of early warning systems based on well-calibrated rainfall thresholds. However, many mountainous areas have little data regarding rainfall and hazards, especially in debris-flow-forming regions. Therefore, the traditional statistical analysis method that determines the empirical relationship between rainstorms and debris flow events cannot be effectively used to calculate reliable rainfall thresholds in these areas. After the severe Wenchuan earthquake, there were plenty of deposits deposited in the gullies, which resulted in several debris flow events. The triggering rainfall threshold has decreased obviously. To get a reliable and accurate rainfall threshold and improve the accuracy of debris flow early warning, this paper developed a quantitative method, which is suitable for debris flow triggering mechanisms in meizoseismal areas, to identify rainfall threshold for debris flow early warning in areas with a scarcity of data based on the initiation mechanism of hydraulic-driven debris flow. First, we studied the characteristics of the study area, including meteorology, hydrology, topography and physical characteristics of the loose solid materials. Then, the rainfall threshold was calculated by the initiation mechanism of the hydraulic debris flow. The comparison with other models and with alternate configurations demonstrates that the proposed rainfall threshold curve is a function of the antecedent precipitation index (API) and 1 h rainfall. To test the proposed method, we selected the Guojuanyan gully, a typical debris flow valley that during the 2008-2013 period experienced several debris flow events, located in the meizoseismal areas of the Wenchuan earthquake, as a case study. The comparison with other

Implications of persistent prehypertension for ageing-related changes in left ventricular geometry and function: the MONICA/KORA Augsburg study.

PubMed

Markus, Marcello Ricardo Paulista; Stritzke, Jan; Lieb, Wolfgang; Mayer, Björn; Luchner, Andreas; Döring, Angela; Keil, Ulrich; Hense, Hans-Werner; Schunkert, Heribert

2008-10-01

It is unclear whether persistent prehypertension causes structural or functional alterations of the heart. We examined echocardiographic data of 1005 adults from a population-based survey at baseline in 1994/1995 and at follow-up in 2004/2005. We compared individuals who had either persistently normal (<120 mmHg systolic and <80 mmHg diastolic, n = 142) or prehypertensive blood pressure (120-139 mmHg or 80-89 mmHg, n = 119) at both examinations using multivariate regression modeling. Over 10 years, left ventricular end-diastolic diameters were stable and did not differ between the two groups. However, the prehypertensive blood pressure group displayed more pronounced ageing-related increases of left ventricular wall thickness (+4.7 versus +11.9%, P < 0.001) and left ventricular mass (+8.6 versus +15.7%, P = 0.006). Prehypertension was associated with a raised incidence of left ventricular concentric remodeling (adjusted odds ratio 10.7, 95% confidence interval 2.82-40.4) and left ventricular hypertrophy (adjusted odds ratio 5.33, 1.58-17.9). The ratio of early and late diastolic peak transmitral flow velocities (E/A) decreased by 7.7% in the normal blood pressure versus 15.7% in the prehypertensive blood pressure group (P = 0.003) and at follow-up the ratio of early diastolic peak transmitral flow and early diastolic peak myocardial relaxation velocities (E/EM) was higher (9.1 versus 8.5, P = 0.031) and left atrial size was larger (36.5 versus 35.3 mm, P = 0.024) in the prehypertensive blood pressure group. Finally, the adjusted odds ratio for incident diastolic dysfunction was 2.52 (1.01-6.31) for the prehypertensive blood pressure group. Persistent prehypertension accelerates the development of hypertrophy and diastolic dysfunction of the heart.

Eocene cooling linked to early flow across the Tasmanian Gateway.

PubMed

Bijl, Peter K; Bendle, James A P; Bohaty, Steven M; Pross, Jörg; Schouten, Stefan; Tauxe, Lisa; Stickley, Catherine E; McKay, Robert M; Röhl, Ursula; Olney, Matthew; Sluijs, Appy; Escutia, Carlota; Brinkhuis, Henk

2013-06-11

The warmest global temperatures of the past 85 million years occurred during a prolonged greenhouse episode known as the Early Eocene Climatic Optimum (52-50 Ma). The Early Eocene Climatic Optimum terminated with a long-term cooling trend that culminated in continental-scale glaciation of Antarctica from 34 Ma onward. Whereas early studies attributed the Eocene transition from greenhouse to icehouse climates to the tectonic opening of Southern Ocean gateways, more recent investigations invoked a dominant role of declining atmospheric greenhouse gas concentrations (e.g., CO2). However, the scarcity of field data has prevented empirical evaluation of these hypotheses. We present marine microfossil and organic geochemical records spanning the early-to-middle Eocene transition from the Wilkes Land Margin, East Antarctica. Dinoflagellate biogeography and sea surface temperature paleothermometry reveal that the earliest throughflow of a westbound Antarctic Counter Current began ~49-50 Ma through a southern opening of the Tasmanian Gateway. This early opening occurs in conjunction with the simultaneous onset of regional surface water and continental cooling (2-4 °C), evidenced by biomarker- and pollen-based paleothermometry. We interpret that the westbound flowing current flow across the Tasmanian Gateway resulted in cooling of Antarctic surface waters and coasts, which was conveyed to global intermediate waters through invigorated deep convection in southern high latitudes. Although atmospheric CO2 forcing alone would provide a more uniform middle Eocene cooling, the opening of the Tasmanian Gateway better explains Southern Ocean surface water and global deep ocean cooling in the apparent absence of (sub-) equatorial cooling.

Eocene cooling linked to early flow across the Tasmanian Gateway

PubMed Central

Bijl, Peter K.; Bendle, James A. P.; Bohaty, Steven M.; Pross, Jörg; Schouten, Stefan; Tauxe, Lisa; Stickley, Catherine E.; McKay, Robert M.; Röhl, Ursula; Olney, Matthew; Sluijs, Appy; Escutia, Carlota; Brinkhuis, Henk; Klaus, Adam; Fehr, Annick; Williams, Trevor; Carr, Stephanie A.; Dunbar, Robert B.; Gonzàlez, Jhon J.; Hayden, Travis G.; Iwai, Masao; Jimenez-Espejo, Francisco J.; Katsuki, Kota; Kong, Gee Soo; Nakai, Mutsumi; Passchier, Sandra; Pekar, Stephen F.; Riesselman, Christina; Sakai, Toyosaburo; Shrivastava, Prakash K.; Sugisaki, Saiko; Tuo, Shouting; van de Flierdt, Tina; Welsh, Kevin; Yamane, Masako

2013-01-01

The warmest global temperatures of the past 85 million years occurred during a prolonged greenhouse episode known as the Early Eocene Climatic Optimum (52–50 Ma). The Early Eocene Climatic Optimum terminated with a long-term cooling trend that culminated in continental-scale glaciation of Antarctica from 34 Ma onward. Whereas early studies attributed the Eocene transition from greenhouse to icehouse climates to the tectonic opening of Southern Ocean gateways, more recent investigations invoked a dominant role of declining atmospheric greenhouse gas concentrations (e.g., CO2). However, the scarcity of field data has prevented empirical evaluation of these hypotheses. We present marine microfossil and organic geochemical records spanning the early-to-middle Eocene transition from the Wilkes Land Margin, East Antarctica. Dinoflagellate biogeography and sea surface temperature paleothermometry reveal that the earliest throughflow of a westbound Antarctic Counter Current began ∼49–50 Ma through a southern opening of the Tasmanian Gateway. This early opening occurs in conjunction with the simultaneous onset of regional surface water and continental cooling (2–4 °C), evidenced by biomarker- and pollen-based paleothermometry. We interpret that the westbound flowing current flow across the Tasmanian Gateway resulted in cooling of Antarctic surface waters and coasts, which was conveyed to global intermediate waters through invigorated deep convection in southern high latitudes. Although atmospheric CO2 forcing alone would provide a more uniform middle Eocene cooling, the opening of the Tasmanian Gateway better explains Southern Ocean surface water and global deep ocean cooling in the apparent absence of (sub-) equatorial cooling. PMID:23720311

Flow Cytometry: Impact On Early Drug Discovery

PubMed Central

Edwards, Bruce S.; Sklar, Larry A.

2015-01-01

Summary Modern flow cytometers can make optical measurements of 10 or more parameters per cell at tens-of-thousands of cells per second and over five orders of magnitude dynamic range. Although flow cytometry is used in most drug discovery stages, “sip-and-spit” sampling technology has restricted it to low sample throughput applications. The advent of HyperCyt sampling technology has recently made possible primary screening applications in which tens-of-thousands of compounds are analyzed per day. Target-multiplexing methodologies in combination with extended multi-parameter analyses enable profiling of lead candidates early in the discovery process, when the greatest numbers of candidates are available for evaluation. The ability to sample small volumes with negligible waste reduces reagent costs, compound usage and consumption of cells. Improved compound library formatting strategies can further extend primary screening opportunities when samples are scarce. Dozens of targets have been screened in 384- and 1536-well assay formats, predominantly in academic screening lab settings. In concert with commercial platform evolution and trending drug discovery strategies, HyperCyt-based systems are now finding their way into mainstream screening labs. Recent advances in flow-based imaging, mass spectrometry and parallel sample processing promise dramatically expanded single cell profiling capabilities to bolster systems level approaches to drug discovery. PMID:25805180

Evaluation of Transmitral Pressure Gradients in the Intraoperative Echocardiographic Diagnosis of Mitral Stenosis after Mitral Valve Repair

PubMed Central

Segal, Scott; Fox, John A.; Eltzschig, Holger K.; Shernan, Stanton K.

2011-01-01

Objective Acute mitral stenosis (MS) following mitral valve (MV) repair is a rare but severe complication. We hypothesize that intraoperative echocardiography can be utilized to diagnose iatrogenic MS immediately after MV repair. Methods The medical records of 552 consecutive patients undergoing MV repair at a single institution were reviewed. Post-cardiopulmonary bypass peak and mean transmitral pressure gradients (TMPG), and pressure half time (PHT) were obtained from intraoperative transesophageal echocardiographic (TEE) examinations in each patient. Results Nine patients (9/552 = 1.6%) received a reoperation for primary MS, prior to hospital discharge. Interestingly, all of these patients already showed intraoperative post-CPB mean and peak TMPGs that were significantly higher compared to values for those who did not: 10.7±4.8 mmHg vs 2.9±1.6 mmHg; p<0.0001 and 22.9±7.9 mmHg vs 7.6±3.7 mmHg; p<0.0001, respectively. However, PHT varied considerably (87±37 ms; range: 20–439 ms) within the entire population, and only weakly predicted the requirement for reoperation (113±56 vs. 87±37 ms, p = 0.034). Receiver operating characteristic curves showed strong discriminating ability for mean gradients (AUC = 0.993) and peak gradients (area under the curve, AUC = 0.996), but poor performance for PHT (AUC = 0.640). A value of ≥7 mmHg for mean, and ≥17 mmHg for peak TMPG, best separated patients who required reoperation for MS from those who did not. Conclusions Intraoperative TEE diagnosis of a peak TMPG ≥17 mmHg or mean TMPG ≥7 mmHg immediately following CPB are suggestive of clinically relevant MS after MV repair. PMID:22087230

Discordance gradient-surface dans le rétrécissement mitral: le gradient moyen transmitral est-il un critère de sévérité ou un indice de tolérance du rétrécissement mitral serré?

PubMed Central

Najih, Hayat; Arous, Salim; Laarje, Aziza; Baghdadi, Dalila; Benouna, Mohamed Ghali; Azzouzi, Leila; Habbal, Rachida

2016-01-01

Le rétrécissement mitral (RM) rhumatismal demeure une valvulopathie fréquente dans les pays en voie de développement. Cependant, les pays industrialisés ont vu l'émergence ces dernières années de nouvelles étiologies de RM; notamment l'origine médicamenteuse et/ou toxique responsable de valvulopathies restrictives aussi bien sténosantes que régurgitantes. Pour cette raison, l'évaluation échocardiographique du RM et surtout, la définition de critères objectifs pour conclure au caractère serré du RM reste toujours d'actualité. Les objectifs du travail sont: évaluer l'existence ou non d'une corrélation directe entre le gradient moyen transmitral (GMT) et la sévérité du RM chez les patients porteurs d'un RM serré ou très serré (critère primaire) et analyser les différents paramètres qui conditionnent le gradient moyen transmitral (GMT) (Critère secondaire). Il s'agit d'une étude transversale monocentrique incluant tous les patients admis au service de Cardiologie du CHU Ibn Rochd de Casablanca pour un RM serré ou très serré, sur une période d'une année (Janvier 2014 à Décembre 2014). Nous avons analysés séparément deux groupes de patients : ceux avec un gradient moyen transmitral<10 mmHg (groupe 1) et ceux avec un gradient>10mmHg (groupe2). 50 patients porteurs d'un RM serré ou très serré ont été inclus. L'âge moyen de nos patients est de 41,7 ans avec prédominance féminine (sex ratio: 0,25). 64% de nos patients avaient un RM serré et 36% avaient un RM très serré. 52% (26 patients) avaient un GMT <10mmHg et 48% (24 patients) avaient un gradient moyen >10mmHg, ce qui suggère l'absence de corrélation directe entre la sévérité du RM et le GMT (coefficient de Pearson R: -0,137). Pour la dyspnée, 80% des patients du groupe 1 étaient dyspnéiques stade II de la NYHA et 70% des patients du groupe 2 étaient dyspnéiques stade III (41%) ou IV (29%) de la NYHA, ce qui signifie l'existence d'une corr

2-D transmitral flows simulation by means of the immersed boundary method on unstructured grids

NASA Astrophysics Data System (ADS)

Denaro, F. M.; Sarghini, F.

2002-04-01

Interaction between computational fluid dynamics and clinical researches recently allowed a deeper understanding of the physiology of complex phenomena involving cardio-vascular mechanisms. The aim of this paper is to develop a simplified numerical model based on the Immersed Boundary Method and to perform numerical simulations in order to study the cardiac diastolic phase during which the left ventricle is filled with blood flowing from the atrium throughout the mitral valve. As one of the diagnostic problems to be faced by clinicians is the lack of a univocal definition of the diastolic performance from the velocity measurements obtained by Eco-Doppler techniques, numerical simulations are supposed to provide an insight both into the physics of the diastole and into the interpretation of experimental data. An innovative application of the Immersed Boundary Method on unstructured grids is presented, fulfilling accuracy requirements related to the development of a thin boundary layer along the moving immersed boundary. It appears that this coupling between unstructured meshes and the Immersed Boundary Method is a promising technique when a wide range of spatial scales is involved together with a moving boundary. Numerical simulations are performed in a range of physiological parameters and a qualitative comparison with experimental data is presented, in order to demonstrate that, despite the simplified model, the main physiological characteristics of the diastole are well represented. Copyright

Flow Cytometry: Impact on Early Drug Discovery.

PubMed

Edwards, Bruce S; Sklar, Larry A

2015-07-01

Modern flow cytometers can make optical measurements of 10 or more parameters per cell at tens of thousands of cells per second and more than five orders of magnitude dynamic range. Although flow cytometry is used in most drug discovery stages, "sip-and-spit" sampling technology has restricted it to low-sample-throughput applications. The advent of HyperCyt sampling technology has recently made possible primary screening applications in which tens of thousands of compounds are analyzed per day. Target-multiplexing methodologies in combination with extended multiparameter analyses enable profiling of lead candidates early in the discovery process, when the greatest numbers of candidates are available for evaluation. The ability to sample small volumes with negligible waste reduces reagent costs, compound usage, and consumption of cells. Improved compound library formatting strategies can further extend primary screening opportunities when samples are scarce. Dozens of targets have been screened in 384- and 1536-well assay formats, predominantly in academic screening lab settings. In concert with commercial platform evolution and trending drug discovery strategies, HyperCyt-based systems are now finding their way into mainstream screening labs. Recent advances in flow-based imaging, mass spectrometry, and parallel sample processing promise dramatically expanded single-cell profiling capabilities to bolster systems-level approaches to drug discovery. © 2015 Society for Laboratory Automation and Screening.

Heat flow vs. atmospheric greenhouse on early Mars

NASA Technical Reports Server (NTRS)

Fanale, F. P.; Postawko, S. E.

1991-01-01

Researchers derived a quantitative relationship between the effectiveness of an atmospheric greenhouse and internal heat flow in producing the morphological differences between earlier and later Martian terrains. The derivation is based on relationships previously derived by other researchers. The reasoning may be stated as follows: the CO2 mean residence time in the Martian atmosphere is almost certainly much shorter than the total time span over which early climate differences are thought to have been sustained. Therefore, recycling of previously degassed CO2 quickly becomes more important than the ongoing supply of juvenile CO2. If so, then the atmospheric CO2 pressure, and thereby the surface temperature, may be approximated mathematically as a function of the total degassed CO2 in the atmosphere plus buried material and the ratio of the atmospheric and regolith mean residence times. The latter ratio can also be expressed as a function of heat flow. Hence, it follows that the surface temperature may be expressed as a function of heat flow and the total amount of available CO2. However, the depth to the water table can simultaneously be expressed as a function of heat flow and the surface temperature (the boundary condition). Therefore, for any given values of total available CO2 and regolith conductivity, there exist coupled independent equations which relate heat flow, surface temperature, and the depth to the water table. This means we can now derive simultaneous values of surface temperature and the depth of the water table for any value of the heat flow. The derived relationship is used to evaluate the relative importance of the atmospheric greenhouse effect and the internal regolith thermal gradient in producing morphological changes for any value of the heat flow, and to assess the absolute importance of each of the values of the heat flow which are thought to be reasonable on independent geophysical grounds.

Estimation of left ventricular operating stiffness from Doppler early filling deceleration time in humans.

PubMed

Garcia, M J; Firstenberg, M S; Greenberg, N L; Smedira, N; Rodriguez, L; Prior, D; Thomas, J D

2001-02-01

Shortened early transmitral deceleration times (E(DT)) have been qualitatively associated with increased filling pressure and reduced survival in patients with cardiac disease and increased left ventricular operating stiffness (K(LV)). An equation relating K(LV) quantitatively to E(DT) has previously been described in a canine model but not in humans. During several varying hemodynamic conditions, we studied 18 patients undergoing open-heart surgery. Transesophageal echocardiographic two-dimensional volumes and Doppler flows were combined with high-fidelity left atrial (LA) and left ventricular (LV) pressures to determine K(LV). From digitized Doppler recordings, E(DT) was measured and compared against changes in LV and LA diastolic volumes and pressures. E(DT) (180 +/- 39 ms) was inversely associated with LV end-diastolic pressures (r = -0.56, P = 0.004) and net atrioventricular stiffness (r = -0.55, P = 0.006) but had its strongest association with K(LV) (r = -0.81, P < 0.001). K(LV) was predicted assuming a nonrestrictive orifice (K(nonrest)) from E(DT) as K(nonrest) = (0.07/E(DT))(2) with K(LV) = 1.01 K(nonrest) - 0.02; r = 0.86, P < 0.001, DeltaK (K(nonrest) - K(LV)) = 0.02 +/- 0.06 mm Hg/ml. In adults with cardiac disease, E(DT) provides an accurate estimate of LV operating stiffness and supports its application as a practical noninvasive index in the evaluation of diastolic function.

Estimation of left ventricular operating stiffness from Doppler early filling deceleration time in humans

NASA Technical Reports Server (NTRS)

Garcia, M. J.; Firstenberg, M. S.; Greenberg, N. L.; Smedira, N.; Rodriguez, L.; Prior, D.; Thomas, J. D.

2001-01-01

Shortened early transmitral deceleration times (E(DT)) have been qualitatively associated with increased filling pressure and reduced survival in patients with cardiac disease and increased left ventricular operating stiffness (K(LV)). An equation relating K(LV) quantitatively to E(DT) has previously been described in a canine model but not in humans. During several varying hemodynamic conditions, we studied 18 patients undergoing open-heart surgery. Transesophageal echocardiographic two-dimensional volumes and Doppler flows were combined with high-fidelity left atrial (LA) and left ventricular (LV) pressures to determine K(LV). From digitized Doppler recordings, E(DT) was measured and compared against changes in LV and LA diastolic volumes and pressures. E(DT) (180 +/- 39 ms) was inversely associated with LV end-diastolic pressures (r = -0.56, P = 0.004) and net atrioventricular stiffness (r = -0.55, P = 0.006) but had its strongest association with K(LV) (r = -0.81, P < 0.001). K(LV) was predicted assuming a nonrestrictive orifice (K(nonrest)) from E(DT) as K(nonrest) = (0.07/E(DT))(2) with K(LV) = 1.01 K(nonrest) - 0.02; r = 0.86, P < 0.001, DeltaK (K(nonrest) - K(LV)) = 0.02 +/- 0.06 mm Hg/ml. In adults with cardiac disease, E(DT) provides an accurate estimate of LV operating stiffness and supports its application as a practical noninvasive index in the evaluation of diastolic function.

Properties of large scale plasma flow during the early stage of the plasmaspheric refilling

NASA Technical Reports Server (NTRS)

Singh, Nagendra; Craven, P.; Torr, D. G.; Richards, P. G.

1990-01-01

The objective is to better characterize the macroscopic properties of the interhemisphere plasma flow by solving a more complete set of hydrodynamic equations than that solved previously. Specifically, the ion continuity, momentum and energy equations were solved for the plasma flow along the closed magnetic field lines. During the initial stage of the supersonic outflow in the equatorial region, the ions cool substantially. Using the hydrodynamic model for the large-scale plasma flow, the dynamics of shocks was examined which form in the geomagnetic flux tubes during the early stages of refilling. These shocks are more like those forming in neutral gases than the electrostatic shocks driven by microinstabilities involving ion-ion interaction. Therefore, the shocks seen in the hydrodynamic model are termed as hydrodynamic shocks. Such shocks are generally unsteady and therefore the usual shock jump conditions given by Rankine-Hugoniot relations are not strictly applicable to them. The density, flow velocity and temperature structures associated with the shocks are examined for both asymmetrical and symmetrical flows. In the asymmetrical flow the outflow from one of two conjugate ionospheres is dominant. On the other hand, in the symmetrical case outflows from the two ionospheric sources are identical. Both cases are treated by a two-stream model. In the late type of flow, the early-time refilling shows a relaxation type of oscillation, which is driven by the large-scale interactions between the two identical streams. After this early stage, the resulting temperature structure shows some interesting features. In the equatorial region the streams are isothermal, but in the off-equatorial regions the streams have quite different temperatures, and also densities and flow velocities. The dense and slow stream is found to be warmer than the low-density fast stream. In the late stage of refilling, the temperature is found to steadily increase from the conjugate

Renal Blood Flow, Glomerular Filtration Rate, and Renal Oxygenation in Early Clinical Septic Shock.

PubMed

Skytte Larsson, Jenny; Krumbholz, Vitus; Enskog, Anders; Bragadottir, Gudrun; Redfors, Bengt; Ricksten, Sven-Erik

2018-06-01

Data on renal hemodynamics, function, and oxygenation in early clinical septic shock are lacking. We therefore measured renal blood flow, glomerular filtration rate, renal oxygen consumption, and oxygenation in patients with early septic shock. Prospective comparative study. General and cardiothoracic ICUs. Patients with norepinephrine-dependent early septic shock (n = 8) were studied within 24 hours after arrival in the ICU and compared with postcardiac surgery patients without acute kidney injury (comparator group, n = 58). None. Data on systemic hemodynamics and renal variables were obtained during two 30-minute periods. Renal blood flow was measured by the infusion clearance of para-aminohippuric acid, corrected for renal extraction of para-aminohippuric acid. Renal filtration fraction was measured by renal extraction of chromium-51 labeled EDTA. Renal oxygenation was estimated from renal oxygen extraction. Renal oxygen delivery (-24%; p = 0.037) and the renal blood flow-to-cardiac index ratio (-21%; p = 0.018) were lower, renal vascular resistance was higher (26%; p = 0.027), whereas renal blood flow tended to be lower (-19%; p = 0.068) in the septic group. Glomerular filtration rate (-32%; p = 0.006) and renal sodium reabsorption (-29%; p = 0.014) were both lower in the septic group. Neither renal filtration fraction nor renal oxygen consumption differed significantly between groups. Renal oxygen extraction was significantly higher in the septic group (28%; p = 0.022). In the septic group, markers of tubular injury were elevated. In early clinical septic shock, renal function was lower, which was accompanied by renal vasoconstriction, a lower renal oxygen delivery, impaired renal oxygenation, and tubular sodium reabsorption at a high oxygen cost compared with controls.

Development of the Patient-specific Cardiovascular Modeling System Using Immersed Boundary Technique

NASA Astrophysics Data System (ADS)

Tay, Wee-Beng; Lin, Liang-Yu; Tseng, Wen-Yih; Tseng, Yu-Heng

2010-05-01

A computational fluid dynamics (CFD) based, patient-specific cardiovascular modeling system is under-developed. The system can identify possible diseased conditions and facilitate physicians' diagnosis at early stage through the hybrid CFD simulation and time-resolved magnetic resonance imaging (MRI). The CFD simulation is initially based on the three-dimensional heart model developed by McQueen and Peskin, which can simultaneously compute fluid motions and elastic boundary motions using the immersed boundary method. We extend and improve the three-dimensional heart model for the clinical application by including the patient-specific hemodynamic information. The flow features in the ventricles and their responses are investigated under different inflow and outflow conditions during diastole and systole phases based on the quasi-realistic heart model, which takes advantage of the observed flow scenarios. Our results indicate distinct differences between the two groups of participants, including the vortex formation process in the left ventricle (LV), as well as the flow rate distributions at different identified sources such as the aorta, vena cava and pulmonary veins/artery. We further identify some key parameters which may affect the vortex formation in the LV. Thus it is hypothesized that disease-related dysfunctions in intervals before complete heart failure can be observed in the dynamics of transmitral blood flow during early LV diastole.

Predictors of residual flow in embolized intracranial ruptured aneurysms at early follow-up.

PubMed

Serafin, Zbigniew; Strześniewski, Piotr; Beuth, Wojciech

2014-01-01

The possibility of recanalization and the need for retreatment are the most important drawbacks of intracranial aneurysm embolization. The purpose of the study was to prospectively analyze the results of early follow-up angiography of embolized ruptured aneurysms in an attempt to determine factors predicting the presence of residual flow. Evaluation included 72 patients with 72 aneurysms, which were followed-up 3 months after the treatment. Analysis of residual flow predictors included: age and gender, clinical state in Hunt-Hess scale, aneurysm localization, aneurysm three dimensions and volume, neck width, sac-to-neck ratio, initial result of embolization, number of coils used and the use of hydrogel coils and stents. Mean sac diameter was 6.5±3.9 mm, and mean neck width was 2.9±1.4 mm. Follow-up angiography presented residual flow in 26 aneurysms (36.1%): class 2 in 8 aneurysms (11.1%), and class 3 in 18 cases (25.0%). Stable aneurysm filling was observed in 45 cases (62.5%), progression of residual flow in 25 cases (34.7%), and regression in 2 cases (2.8%). According to ROC analysis independent predictors of residual flow were aneurysm neck diameter (AUC 0.857, 95% CI: 0.755-0.928, p<0.0001) and sac-to-neck ratio (AUC 0.817, 95% CI: 0.708-0.898, p<0.0001). Cut-off point of the ROC curve was established at 2.8 mm for neck diameter, and 1.73 for sac-to-neck ratio. Aneurysm neck diameter and sac-to-neck ratio are independently related to the residual flow in embolized ruptured aneurysms at early follow-up.

Debris flow early warning systems in Norway: organization and tools

NASA Astrophysics Data System (ADS)

Kleivane, I.; Colleuille, H.; Haugen, L. E.; Alve Glad, P.; Devoli, G.

2012-04-01

In Norway, shallow slides and debris flows occur as a combination of high-intensity precipitation, snowmelt, high groundwater level and saturated soil. Many events have occurred in the last decades and are often associated with (or related to) floods events, especially in the Southern of Norway, causing significant damages to roads, railway lines, buildings, and other infrastructures (i.e November 2000; August 2003; September 2005; November 2005; Mai 2008; June and Desember 2011). Since 1989 the Norwegian Water Resources and Energy Directorate (NVE) has had an operational 24 hour flood forecasting system for the entire country. From 2009 NVE is also responsible to assist regions and municipalities in the prevention of disasters posed by landslides and snow avalanches. Besides assisting the municipalities through implementation of digital landslides inventories, susceptibility and hazard mapping, areal planning, preparation of guidelines, realization of mitigation measures and helping during emergencies, NVE is developing a regional scale debris flow warning system that use hydrological models that are already available in the flood warning systems. It is well known that the application of rainfall thresholds is not sufficient to evaluate the hazard for debris flows and shallow slides, and soil moisture conditions play a crucial role in the triggering conditions. The information on simulated soil and groundwater conditions and water supply (rain and snowmelt) based on weather forecast, have proved to be useful variables that indicate the potential occurrence of debris flows and shallow slides. Forecasts of runoff and freezing-thawing are also valuable information. The early warning system is using real-time measurements (Discharge; Groundwater level; Soil water content and soil temperature; Snow water equivalent; Meteorological data) and model simulations (a spatially distributed version of the HBV-model and an adapted version of 1-D soil water and energy balance

Diastolic heart failure associated with hemangiosarcoma infiltrating left ventricular walls in a dog.

PubMed

Osuga, Tatsuyuki; Nakamura, Kensuke; Morita, Tomoya; Kagawa, Yumiko; Ohta, Hiroshi; Takiguchi, Mitsuyoshi

2017-11-01

A 9-year-old Shetland sheepdog was diagnosed with cardiogenic pulmonary edema. Echocardiography revealed focally thickened left ventricular free wall and interventricular septum and left atrial dilation. Left ventricular systolic function was preserved. Doppler echocardiography of transmitral flow indicated restrictive left ventricular filling. Cardiac histopathology demonstrated hemangiosarcoma infiltrating the left ventricular walls.

Miniaturized Water Flow and Level Monitoring System for Flood Disaster Early Warning

NASA Astrophysics Data System (ADS)

Ifedapo Abdullahi, Salami; Hadi Habaebi, Mohamed; Surya Gunawan, Teddy; Rafiqul Islam, MD

2017-11-01

This study presents the performance of a prototype miniaturised water flow and water level monitoring sensor designed towards supporting flood disaster early warning systems. The design involved selection of sensors, coding to control the system mechanism, and automatic data logging and storage. During the design phase, the apparatus was constructed where all the components were assembled using locally sourced items. Subsequently, under controlled laboratory environment, the system was tested by running water through the inlet during which the flow rate and rising water levels are automatically recorded and stored in a database via Microsoft Excel using Coolterm software. The system is simulated such that the water level readings measured in centimeters is output in meters using a multiplicative of 10. A total number of 80 readings were analyzed to evaluate the performance of the system. The result shows that the system is sensitive to water level rise and yielded accurate measurement of water level. But, the flow rate fluctuates due to the manual water supply that produced inconsistent flow. It was also observed that the flow sensor has a duty cycle of 50% of operating time under normal condition which implies that the performance of the flow sensor is optimal.

Flow Test to Predict Early Hypotony and Hypertensive Phase After Ahmed Glaucoma Valve (AGV) Surgical Implantation.

PubMed

Cheng, Jason; Beltran-Agullo, Laura; Buys, Yvonne M; Moss, Edward B; Gonzalez, Johanna; Trope, Graham E

2016-06-01

To assess the validity of a preimplantation flow test to predict early hypotony [intraocular pressure (IOP)≤5 mm Hg on 2 consecutive visits and hypertensive phase (HP) (IOP>21 mm Hg) after Ahmed Glaucoma Valve (AGV) implantation. Prospective interventional study on patients receiving an AGV. A preimplantation flow test using a gravity-driven reservoir and an open manometer was performed on all AGVs. Opening pressure (OP) and closing pressure (CP) were defined as the pressure at which fluid was seen to flow or stop flowing through the AGV, respectively. OP and CP were measured twice per AGV. Patients were followed for 12 weeks. In total, 20 eyes from 19 patients were enrolled. At 12 weeks the mean IOP decreased from 29.2±9.1 to 16.8±5.2 mm Hg (P<0.01). The mean AGV OP was 17.5±5.4 mm Hg and the mean CP was 6.7±2.3 mm Hg. Early (within 2 wk postoperative) HP occurred in 37% and hypotony in 16% of cases. An 18 mm Hg cutoff for the OP gave a sensitivity of 0.71, specificity of 0.83, positive predictive value of 0.71, and negative predictive value of 0.83 for predicting an early HP. A 7 mm Hg cutoff for the CP yielded a sensitivity of 1.0, specificity of 0.38, positive predictive value of 0.23, and negative predictive value of 1.0 for predicting hypotony. Preoperative OP and CP may predict early hypotony or HP and may be used as a guide as to which AGV valves to discard before implantation surgery.

Diastolic heart failure associated with hemangiosarcoma infiltrating left ventricular walls in a dog

PubMed Central

Osuga, Tatsuyuki; Nakamura, Kensuke; Morita, Tomoya; Kagawa, Yumiko; Ohta, Hiroshi; Takiguchi, Mitsuyoshi

2017-01-01

A 9-year-old Shetland sheepdog was diagnosed with cardiogenic pulmonary edema. Echocardiography revealed focally thickened left ventricular free wall and interventricular septum and left atrial dilation. Left ventricular systolic function was preserved. Doppler echocardiography of transmitral flow indicated restrictive left ventricular filling. Cardiac histopathology demonstrated hemangiosarcoma infiltrating the left ventricular walls. PMID:29089652

E-wave generated intraventricular diastolic vortex to L-wave relation: model-based prediction with in vivo validation.

PubMed

Ghosh, Erina; Caruthers, Shelton D; Kovács, Sándor J

2014-08-01

The Doppler echocardiographic E-wave is generated when the left ventricle's suction pump attribute initiates transmitral flow. In some subjects E-waves are accompanied by L-waves, the occurrence of which has been correlated with diastolic dysfunction. The mechanisms for L-wave generation have not been fully elucidated. We propose that the recirculating diastolic intraventricular vortex ring generates L-waves and based on this mechanism, we predict the presence of L-waves in the right ventricle (RV). We imaged intraventricular flow using Doppler echocardiography and phase-contrast magnetic resonance imaging (PC-MRI) in 10 healthy volunteers. L-waves were recorded in all subjects, with highest velocities measured typically 2 cm below the annulus. Fifty-five percent of cardiac cycles (189 of 345) had L-waves. Color M-mode images eliminated mid-diastolic transmitral flow as the cause of the observed L-waves. Three-dimensional intraventricular flow patterns were imaged via PC-MRI and independently validated our hypothesis. Additionally as predicted, L-waves were observed in the RV, by both echocardiography and PC-MRI. The re-entry of the E-wave-generated vortex ring flow through a suitably located echo sample volume can be imaged as the L-wave. These waves are a general feature and a direct consequence of LV and RV diastolic fluid mechanics. Copyright © 2014 the American Physiological Society.

In vivo photoacoustic flow cytometry for early malaria diagnosis.

PubMed

Cai, Chengzhong; Carey, Kai A; Nedosekin, Dmitry A; Menyaev, Yulian A; Sarimollaoglu, Mustafa; Galanzha, Ekaterina I; Stumhofer, Jason S; Zharov, Vladimir P

2016-06-01

In vivo photoacoustic (PA) flow cytometry (PAFC) has already demonstrated a great potential for the diagnosis of deadly diseases through ultrasensitive detection of rare disease-associated circulating markers in whole blood volume. Here, we demonstrate the first application of this powerful technique for early diagnosis of malaria through label-free detection of malaria parasite-produced hemozoin in infected red blood cells (iRBCs) as high-contrast PA agent. The existing malaria tests using blood smears can detect the disease at 0.001-0.1% of parasitemia. On the contrary, linear PAFC showed a potential for noninvasive malaria diagnosis at an extremely low level of parasitemia of 0.0000001%, which is ∼10(3) times better than the existing tests. Multicolor time-of-flight PAFC with high-pulse repetition rate lasers at wavelengths of 532, 671, and 820 nm demonstrated rapid spectral and spatial identification and quantitative enumeration of individual iRBCs. Integration of PAFC with fluorescence flow cytometry (FFC) provided real-time simultaneous detection of single iRBCs and parasites expressing green fluorescence proteins, respectively. A combination of linear and nonlinear nanobubble-based multicolor PAFC showed capability to real-time control therapy efficiency by counting of iRBCs before, during, and after treatment. Our results suggest that high-sensitivity, high-resolution ultrafast PAFC-FFC platform represents a powerful research tool to provide the insight on malaria progression through dynamic study of parasite-cell interactions directly in bloodstream, whereas portable hand-worn PAFC device could be broadly used in humans for early malaria diagnosis. © 2016 International Society for Advancement of Cytometry. © 2016 International Society for Advancement of Cytometry.

Cooling flows and X-ray emission in early-type galaxies

NASA Technical Reports Server (NTRS)

Sarazin, Craig L.

1990-01-01

The X-ray properties of normal early-type galaxies and the limited theoretical understanding of the physics of the hot interstellar medium in these galaxies are reviewed. A number of simple arguments about the physical state of the gas are given. Steady-state cooling flow models for these galaxies are presented, and their time-dependent evolution is discussed. The X-ray emission found in early-type galaxies indicates that they contain significant amounts of hot interstellar gas, and that they are not the gas-poor systems they were previously thought to be. In the brighter X-ray galaxies, the amounts of hot gas observed are consistent with those expected given the present rates of stellar mass loss. The required rates of heating of the gas are consistent with those expected from the motions of gas-losing stars and supernovae. The X-ray observations are generally more consistent with a lower rate of Type I supernovae than was previously thought.

Acceleration rate of mitral inflow E wave: a novel transmitral doppler index for assessing diastolic function.

PubMed

Badkoubeh, Roya Sattarzadeh; Tavoosi, Anahita; Jabbari, Mostafa; Parsa, Amir Farhang Zand; Geraeli, Babak; Saadat, Mohammad; Larti, Farnoosh; Meysamie, Ali Pasha; Salehi, Mehrdad

2016-06-10

We performed comprehensive transmitral and pulmonary venous Doppler echocardiographic studies to devise a novel index of diastolic function. This is the first study to assess the utility of the acceleration rate (AR) of the E wave of mitral inflow as a primary diagnostic modality for assessing diastolic function. Study group consisted of 84 patients (53 + 11 years) with left ventricle (LV) diastolic dysfunction and 34 healthy people (35 ± 9 years) as control group, who were referred for clinically indicated two-dimensional transthoracic echocardiogram (TTE) during 2012 and 2013 to Imam Hospital. Normal controls were defined as patients without clinical evidence of cardiac disease and had normal TTE. LV diastolic function was determined according to standardized protocol of American Society of Echocardiography (ASE). As our new parameter, AR of E wave of mitral inflow was also measured in all patients. It was represented by the slope of the line between onset of E wave and peak of it. Correlation between AR of E wave and LV diastolic function grade was measured using the Spearman correlation coefficient. Receiver operating characteristic (ROC) curve was used to determine the sensitivity and specificity of AR of E wave in diagnosing LV diastolic dysfunction in randomly selected two-thirds of population then its derived cutoff was evaluated in rest of the population. The institutional review board of the hospital approved the study protocol. All participants gave written informed consent. This investigation was in accordance with the Declaration of Helsinki. The mean value of AR was 1010 ± 420 cm/s(2) in patients whereas the mean value for the normal controls was 701 ± 210 cm/s(2). There was a strong and graded relation between AR of E wave of mitral inflow and LV diastolic function grade (Spearman P ≤0.0001, rs =0.69). ROC curve analysis revealed that AR of E wave of mitral inflow =750 cm/s(2) predicted moderate or severe LV diastolic

Cardiovascular health profile of elite female football players compared to untrained controls before and after short-term football training.

PubMed

Randers, Morten Bredsgaard; Andersen, Lars Juel; Orntoft, Christina; Bendiksen, Mads; Johansen, Lars; Horton, Joshua; Hansen, Peter Riis; Krustrup, Peter

2013-01-01

This study examined the intermittent exercise performance and cardiovascular health profile in elite female football players in comparison to untrained young women, as well as a subgroup subjected to football training 2x1 h · week(-1) for 16 weeks. Twenty-seven Danish national team players (elite trained, ET) and 28 untrained women (UT) underwent dual-energy X-ray absorptiometry-scanning (DXA), comprehensive transthoracic echocardiography, treadmill and Yo-Yo Intermittent Endurance level 2 (IE2) testing. Eight women in UT were also tested after the football training period. Maximal oxygen uptake rate (VO2max), peak ventilation and peak lactate were 40, 18 and 51% higher (P< 0.01) in ET than UT, respectively. Cardiac dimensions and function were greater in ET than UT, with left ventricular diastolic diameter, right ventricular diastolic diameter, tricuspid annular plane systolic excursion (TAPSE) and peak transmitral flow in early diastole divided by peak transmitral flow velocity in late diastole during atrial contraction (E/A-ratio) being 13, 19, 27 and 41%, respectively, greater in ET than UT (P< 0.001 to< 0.05). Yo-Yo IE2 performance was 7-fold higher in ET than UT (1772 ± 508 vs. 234 ± 66 m, P< 0.001), fat mass was 51% lower (P< 0.001) and high density lipoprotein (HDL) cholesterol levels were 20% higher (P< 0.01). Sixteen weeks of football elevated VO2max and Yo-Yo IE2 performance by 16 and 40%, respectively, and lowered fat mass by 6%. Cardiac function was markedly improved by 16 weeks of football training with 26 and 46% increases in TAPSE and E/A ratio, respectively, reaching levels comparable to ET. In summary, elite female football players have a superior cardiovascular health profile and intermittent exercise performance compared to untrained controls, but short-term football training can markedly improve the cardiovascular health status.

Radioisotope penile plethysmography: A technique for evaluating corpora cavernosal blood flow during early tumescence

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

Schwartz, A.N.; Graham, M.M.; Ferency, G.F.

1989-04-01

Radioisotope penile plethysmography is a nuclear medicine technique which assists in the evaluation of patients with erectile dysfunction. This technique attempts to noninvasively quantitate penile corpora cavernosal blood flow during early penile tumescence using technetium-99m-labeled red blood cells. Penile images and counts were acquired in a steady-state blood-pool phase prior to and after the administration of intracorporal papaverine. Penile counts, images, and time-activity curves were computer analyzed in order to determine peak corporal flow and volume changes. Peak corporal flow rates were compared to arterial integrity (determined by angiography) and venosinusoidal corporal leak (determined by cavernosometry). Peak corporal flow correlatedmore » well with arterial integrity (r = 0.91) but did not correlate with venosinusoidal leak parameters (r = 0.01). This report focuses on the methodology and the assumptions which form the foundation of this technique. The strong correlation of peak corporal flow and angiography suggests that radioisotope penile plethysmography could prove useful in the evaluation of arterial inflow disorders in patients with erectile dysfunction.« less

Vortex flow during early and late left ventricular filling in normal subjects: quantitative characterization using retrospectively-gated 4D flow cardiovascular magnetic resonance and three-dimensional vortex core analysis.

PubMed

Elbaz, Mohammed S M; Calkoen, Emmeline E; Westenberg, Jos J M; Lelieveldt, Boudewijn P F; Roest, Arno A W; van der Geest, Rob J

2014-09-27

LV diastolic vortex formation has been suggested to critically contribute to efficient blood pumping function, while altered vortex formation has been associated with LV pathologies. Therefore, quantitative characterization of vortex flow might provide a novel objective tool for evaluating LV function. The objectives of this study were 1) assess feasibility of vortex flow analysis during both early and late diastolic filling in vivo in normal subjects using 4D Flow cardiovascular magnetic resonance (CMR) with retrospective cardiac gating and 3D vortex core analysis 2) establish normal quantitative parameters characterizing 3D LV vortex flow during both early and late ventricular filling in normal subjects. With full ethical approval, twenty-four healthy volunteers (mean age: 20±10 years) underwent whole-heart 4D Flow CMR. The Lambda2-method was used to extract 3D LV vortex ring cores from the blood flow velocity field during early (E) and late (A) diastolic filling. The 3D location of the center of vortex ring core was characterized using cylindrical cardiac coordinates (Circumferential, Longitudinal (L), Radial (R)). Comparison between E and A filling was done with a paired T-test. The orientation of the vortex ring core was measured and the ring shape was quantified by the circularity index (CI). Finally, the Spearman's correlation between the shapes of mitral inflow pattern and formed vortex ring cores was tested. Distinct E- and A-vortex ring cores were observed with centers of A-vortex rings significantly closer to the mitral valve annulus (E-vortex L=0.19±0.04 versus A-vortex L=0.15±0.05; p=0.0001), closer to the ventricle's long-axis (E-vortex: R=0.27±0.07, A-vortex: R=0.20±0.09, p=0.048) and more elliptical in shape (E-vortex: CI=0.79±0.09, A-vortex: CI=0.57±0.06; <0.001) compared to E-vortex. The circumferential location and orientation relative to LV long-axis for both E- and A-vortex ring cores were similar. Good to strong correlation was found

Eruptive history of the Karoo lava flows and their impact on early Jurassic environmental change

NASA Astrophysics Data System (ADS)

Moulin, M.; Fluteau, F.; Courtillot, V.; Marsh, J.; Delpech, G.; Quidelleur, X.; Gérard, M.

2017-02-01

This paper reports new paleomagnetic and geochronologic data from a 1500 m thick composite section belonging to the Drakensberg group, the thickest remnant of the Karoo lavas in Northern Lesotho. Flow-by-flow analysis of paleomagnetic directions reveals 21 magnetic directional groups, corresponding to single eruptive events, and 16 individual lava flows. The new age determinations of lava flows range from 180.1 ± 1.4 to 182.8 ± 2.6 Ma. These data, combined with previous results, allow us to propose that the main part of the Drakensberg group and the Karoo intrusive complex dated around 181-183 Ma may have been erupted over a period as short as 250 kyr and may have coincided with the two main phases of extinction in the Early Toarcian. This scenario agrees well with the discontinuous rhythm of environmental and biotic perturbations in the Late Pliensbachian-Toarcian interval.

Early and progressive impairment of spinal blood flow-glucose metabolism coupling in motor neuron degeneration of ALS model mice.

PubMed

Miyazaki, Kazunori; Masamoto, Kazuto; Morimoto, Nobutoshi; Kurata, Tomoko; Mimoto, Takahumi; Obata, Takayuki; Kanno, Iwao; Abe, Koji

2012-03-01

The exact mechanism of selective motor neuron death in amyotrophic lateral sclerosis (ALS) remains still unclear. In the present study, we performed in vivo capillary imaging, directly measured spinal blood flow (SBF) and glucose metabolism, and analyzed whether if a possible flow-metabolism coupling is disturbed in motor neuron degeneration of ALS model mice. In vivo capillary imaging showed progressive decrease of capillary diameter, capillary density, and red blood cell speed during the disease course. Spinal blood flow was progressively decreased in the anterior gray matter (GM) from presymptomatic stage to 0.80-fold of wild-type (WT) mice, 0.61 at early-symptomatic, and 0.49 at end stage of the disease. Local spinal glucose utilization (LSGU) was transiently increased to 1.19-fold in anterior GM at presymptomatic stage, which in turn progressively decreased to 0.84 and 0.60 at early-symptomatic and end stage of the disease. The LSGU/SBF ratio representing flow-metabolism uncoupling (FMU) preceded the sequential pathological changes in the spinal cord of ALS mice and was preferentially found in the affected region of ALS. The present study suggests that this early and progressive FMU could profoundly involve in the whole disease process as a vascular factor of ALS pathology, and could also be a potential target for therapeutic intervention of ALS.

Thermographic evaluation of early melanoma within the vascularized skin using combined non-Newtonian blood flow and bioheat models.

PubMed

Bhowmik, Arka; Repaka, Ramjee; Mishra, Subhash C

2014-10-01

A theoretical study on vascularized skin model to predict the thermal evaluation criteria of early melanoma using the dynamic thermal imaging technique is presented in this article. Thermographic evaluation of melanoma has been carried out during the thermal recovery of skin from undercooled condition. During thermal recovery, the skin has been exposed to natural convection, radiation, and evaporation. The thermal responses of melanoma have been evaluated by integrating the bioheat model for multi-layered skin with the momentum as well as energy conservation equations for blood flow. Differential changes in the surface thermal response of various melanoma stages except that of the early stage have been determined. It has been predicted that the thermal response due to subsurface blood flow overpowers the response of early melanoma. Hence, the study suggests that the quantification of early melanoma diagnosis using thermography has not reached a matured stage yet. Therefore, the study presents a systematic analysis of various intermediate melanoma stages to determine the thermal evaluation criteria of early melanoma. The comprehensive modeling effort made in this work supports the prediction of the disease outcome and relates the thermal response with the variation in patho-physiological, thermal and geometrical parameters. Copyright © 2014 Elsevier Ltd. All rights reserved.

Intracellular pH in early Xenopus embryos: its effect on current flow between blastomeres.

PubMed Central

Turin, L; Warner, A E

1980-01-01

1. Electrophysiological techniques were used to monitor the flow of electric current from one cell to the next in Xenopus laevis embryos between the 4-cell and early blastula stages of development. Intracellular pH and blastocoel pH were determined using pH-sensitive micro-electrodes. 2. The resting intracellular pH was 7.74+/-0.02 (S.E. of mean, n = 29); there were no systematic differences between developmental stages. Blastocoel cavity pH was 8.4+/-0.06 (S.E. of mean, n = 10). The intracellular buffer value was 18 m-equiv. H+/pH unit per litre. 3. In embryos treated with bicarbonate buffered Holtfreter solution equilibrated with 100% CO2 the intracellular pH fell to 6.3+/-0.17 (S.D., n = 8). The membrane potential fell and the input resistance increased. The size of the effect on membrane potential and input resistance varied. 4. From the 32-cell stage onwards current flow from one cell to the next was abolished when the intracellular pH fell to below 6.5; the effect was rapid in onset and completely reversible. At cleavage stages of development lowering intracellular pH with CO2 had no effect on current flow from cell to cell. 5. The relationship between intracellular pH and current flow from cell to cell was sigmoid and covered between 0.2 and 0.4 pH units. The pH at which current flow was completely abolished ranged from 6.85 to 6.4. 6. Alterations in extraembryonic pH over the range 5.8-7.5 had no effect on any parameter measured. 7. We conclude that lowering the intracellular pH increases the resistance of both non-junctional junctional membranes. The data do not allow us to extract the pH junctional conductance relationship. 8. Variations in intracellular pH may provide a useful tool for the study of the functional role of direct cell to cell communication in both adult organs and early embryos. PMID:6770084

Identification of Location Specific Feature Points in a Cardiac Cycle Using a Novel Seismocardiogram Spectrum System.

PubMed

Lin, Wen-Yen; Chou, Wen-Cheng; Chang, Po-Cheng; Chou, Chung-Chuan; Wen, Ming-Shien; Ho, Ming-Yun; Lee, Wen-Chen; Hsieh, Ming-Jer; Lin, Chung-Chih; Tsai, Tsai-Hsuan; Lee, Ming-Yih

2018-03-01

Seismocardiogram (SCG) or mechanocardiography is a noninvasive cardiac diagnostic method; however, previous studies used only a single sensor to detect cardiac mechanical activities that will not be able to identify location-specific feature points in a cardiac cycle corresponding to the four valvular auscultation locations. In this study, a multichannel SCG spectrum measurement system was proposed and examined for cardiac activity monitoring to overcome problems like, position dependency, time delay, and signal attenuation, occurring in traditional single-channel SCG systems. ECG and multichannel SCG signals were simultaneously recorded in 25 healthy subjects. Cardiac echocardiography was conducted at the same time. SCG traces were analyzed and compared with echocardiographic images for feature point identification. Fifteen feature points were identified in the corresponding SCG traces. Among them, six feature points, including left ventricular lateral wall contraction peak velocity, septal wall contraction peak velocity, transaortic peak flow, transpulmonary peak flow, transmitral ventricular relaxation flow, and transmitral atrial contraction flow were identified. These new feature points were not observed in previous studies because the single-channel SCG could not detect the location-specific signals from other locations due to time delay and signal attenuation. As the results, the multichannel SCG spectrum measurement system can record the corresponding cardiac mechanical activities with location-specific SCG signals and six new feature points were identified with the system. This new modality may help clinical diagnoses of valvular heart diseases and heart failure in the future.

Investigating the Early Atmospheres of Earth and Mars through Rivers, Raindrops, and Lava Flows

NASA Astrophysics Data System (ADS)

Som, Sanjoy M.

2010-11-01

The discovery of a habitable Earth-like planet beyond our solar-system will be remembered as one of the major breakthroughs of 21st century science, and of the same magnitude as Copernicus' heliocentric model dating from the mid 16th century. The real astrobiological breakthrough will be the added results from atmospheric remote sensing of such planets to determine habitability. Atmospheres, in both concentration and composition are suggestive of processes occurring at the planetary surface and upper crust. Unfortunately, only the modern Earth's atmosphere is known to be habitable. I investigate the density and pressure of our planet's early atmosphere before the rise of oxygen 2.5 billion years ago, because our planet was very much alive microbially. Such knowledge gives us another example of a habitable atmosphere. I also investigates the atmosphere of early Mars, as geomorphic signatures on its surface are suggestive of a past where liquid water may have present in a warmer climate, conditions suitable for the emergence of life, compared with today's 6 mbar CO2-dominated atmosphere. Using tools of fluvial geomorphology, I find that the largest river-valleys on Mars do not record a signature of a sustained hydrological cycle, in which precipitation onto a drainage basin induces many cycles of water flow, substrate incision, water ponding, and return to the atmosphere via evaporation. Rather, I conclude that while episodes of flow did occur in perhaps warmer environments, those periods were short-lived and overprinted onto a dominantly cold and dry planet. For Earth, I develop a new method of investigating atmospheric density and pressure using the size of raindrop imprints, and find that raindrop imprints preserved in the 2.7 billion year old Ventersdorp Supergroup of South Africa are consistent with precipitation falling in an atmosphere of near-surface density < 2 kg/m3 and probably > 0.1 kg/m3, compared to a modern value of 1.2 kg/m3, further suggesting a

Noninvasive assessment of mitral inertness [correction of inertance]: clinical results with numerical model validation.

PubMed

Firstenberg, M S; Greenberg, N L; Smedira, N G; McCarthy, P M; Garcia, M J; Thomas, J D

2001-01-01

Inertial forces (Mdv/dt) are a significant component of transmitral flow, but cannot be measured with Doppler echo. We validated a method of estimating Mdv/dt. Ten patients had a dual sensor transmitral (TM) catheter placed during cardiac surgery. Doppler and 2D echo was performed while acquiring LA and LV pressures. Mdv/dt was determined from the Bernoulli equation using Doppler velocities and TM gradients. Results were compared with numerical modeling. TM gradients (range: 1.04-14.24 mmHg) consisted of 74.0 +/- 11.0% inertial forcers (range: 0.6-12.9 mmHg). Multivariate analysis predicted Mdv/dt = -4.171(S/D (RATIO)) + 0.063(LAvolume-max) + 5. Using this equation, a strong relationship was obtained for the clinical dataset (y=0.98x - 0.045, r=0.90) and the results of numerical modeling (y=0.96x - 0.16, r=0.84). TM gradients are mainly inertial and, as validated by modeling, can be estimated with echocardiography.

Noninvasive assessment of mitral inertness: clinical results with numerical model validation

NASA Technical Reports Server (NTRS)

Firstenberg, M. S.; Greenberg, N. L.; Smedira, N. G.; McCarthy, P. M.; Garcia, M. J.; Thomas, J. D.

2001-01-01

Inertial forces (Mdv/dt) are a significant component of transmitral flow, but cannot be measured with Doppler echo. We validated a method of estimating Mdv/dt. Ten patients had a dual sensor transmitral (TM) catheter placed during cardiac surgery. Doppler and 2D echo was performed while acquiring LA and LV pressures. Mdv/dt was determined from the Bernoulli equation using Doppler velocities and TM gradients. Results were compared with numerical modeling. TM gradients (range: 1.04-14.24 mmHg) consisted of 74.0 +/- 11.0% inertial forcers (range: 0.6-12.9 mmHg). Multivariate analysis predicted Mdv/dt = -4.171(S/D (RATIO)) + 0.063(LAvolume-max) + 5. Using this equation, a strong relationship was obtained for the clinical dataset (y=0.98x - 0.045, r=0.90) and the results of numerical modeling (y=0.96x - 0.16, r=0.84). TM gradients are mainly inertial and, as validated by modeling, can be estimated with echocardiography.

An experimental flow-through assessment of acidic Fe/Mg smectite formation on early Mars

NASA Astrophysics Data System (ADS)

Sutter, B.; Peretyazhko, T.; Garcia, A. H.; Ming, D. W.

2017-12-01

Orbital observations have detected the phyllosilicate smectite in layered material hundreds of meters thick, intracrater depositional fans, and plains sediments on Mars; however, the detection of carbonate deposits is limited. Instead of neutral/alkaline conditions during the Noachian, early Mars may have experienced mildly acidic conditions derived from volcanic acid-sulfate solutions that allowed Fe/Mg smectite formation but prevented widespread carbonate formation. The detection of acid sulfates (e.g., jarosite) associated with smectite in Mawrth Vallis supports this hypothesis. Previous work demonstrated smectite (saponite) formation in closed hydrologic systems (batch reactor) from basaltic glass at pH 4 and 200°C (Peretyazhko et al., 2016 GCA). This work presents results from alteration of basaltic glass from alkaline to acidic conditions in open hydrologic systems (flow-through reactor). Preliminary experiments exposed basaltic glass to deionized water at 190°C at 0.25 ml/min where solution pH equilibrated to 9.5. These initial high pH experiments were conducted to evaluate the flow-through reactor system before working with lower pHs. Smectite at this pH was not produced and instead X-ray diffraction results consistent with serpentine was detected. Experiments are in progress exposing basaltic glass from pH 8 down to pH 3 to determine what range of pHs could allow for smectite formation in this experimental open-system. The production of smectite under an experimental open-system at low pHs if successful, would support a significant paradigm shift regarding the geochemical evolution of early Mars: Early Mars geochemical solutions were mildly acidic, not neutral/alkaline. This could have profound implications regarding early martain microbiology where acid conditions instead of neutral/alkaline conditions will require further research in terrestrial analogs to address the potential for biosignature preservation on Mars (Johnson et al., 2016, LPSC).

Left ventricular structural and functional characteristics in Cushing's syndrome.

PubMed

Muiesan, Maria Lorenza; Lupia, Mario; Salvetti, Massimo; Grigoletto, Consuelo; Sonino, Nicoletta; Boscaro, Marco; Rosei, Enrico Agabiti; Mantero, Franco; Fallo, Francesco

2003-06-18

This study was designed to evaluate left ventricular (LV) anatomy and function in patients with Cushing's syndrome. A high prevalence of LV hypertrophy and concentric remodeling has been reported in Cushing's syndrome, although no data have been reported on LV systolic and diastolic function. Forty-two consecutive patients with Cushing's syndrome and 42 control subjects, matched for age, gender, and blood pressure, were studied. Left ventricular mass index (LVMI) and relative wall thickness (RWT) were measured by echocardiography, endocardial and midwall fractional shortening (FS) were assessed, and diastolic filling was measured by Doppler transmitral flow. The RWT was significantly greater in Cushing patients than in controls. Left ventricular hypertrophy and concentric remodeling were observed in 10 and 26 patients with Cushing's syndrome, respectively. In Cushing patients, midwall FS was significantly reduced compared with controls (16.2 +/- 3% vs. 21 +/- 4.5%, p = 0.01). The ratio of transmitral E and A flow velocities was reduced and E deceleration time was prolonged in Cushing patients compared with controls (p = 0.03 and p < 0.001, respectively). In patients with Cushing's syndrome, cardiac structural changes are associated with reduced midwall systolic performance and with diastolic dysfunction that may contribute to the high risk of cardiovascular events observed in these patients.

Effects of Experimental High Flow Releases and Increased Fluctuations in Flow from Glen Canyon Dam on Abundance, Growth, and Survival Rates of Early Life Stages of Rainbow Trout in the Lee's Ferry Reach of the Colorado River

NASA Astrophysics Data System (ADS)

Korman, Josh

2010-05-01

The abundance of adult fish populations is controlled by the growth and survival rates of early life stages. Evaluating the effects of flow regimes on early life stages is therefore critical to determine how these regimes affect the abundance of adult populations. Experimental high flow releases from Glen Canyon Dam, primarily intended to conserve fine sediment and improve habitat conditions for native fish in the Colorado River in Grand Canyon, AZ, have been conducted in 1996, 2004, and 2008. These flows potentially affect the Lee's Ferry reach rainbow trout population, located immediately downstream of the dam, which supports a highly valued fishery and likely influences the abundance of rainbow trout in Grand Canyon. Due to concerns about negative effects of high trout abundance on endangered native fish, hourly variation in flow from Glen Canyon Dam was experimentally increased between 2003 and 2005 to reduce trout abundance. This study reports on the effects of experimental high flow releases and fluctuating flows on early life stages of rainbow trout in the Lee's Ferry reach based on monthly sampling of redds (egg nests) and the abundance and growth of age-0 trout between 2003 and 2009. Data on spawn timing, spawning elevations, and intergravel temperatures were integrated in a model to estimate the magnitude and seasonal trend in incubation mortality resulting from redd dewatering due to fluctuations in flow. Experimental fluctuations from January through March promoted spawning at higher elevations where the duration of dewatering was longer and intergravel temperatures exceeded lethal thresholds. Flow-dependent incubation mortality rates were 24% (2003) and 50% (2004) in years with higher flow fluctuations, compared to 5-11% under normal operations (2006-2009). Spatial and temporal predictions of mortality were consistent with direct observations of egg mortality determined from the excavation of 125 redds. The amount of variation in backcalculated hatch

Early-Morning Flow Transition in a Valley in Low-Mountain Terrain Under Clear-Sky Conditions

NASA Astrophysics Data System (ADS)

Brötz, Björn; Eigenmann, Rafael; Dörnbrack, Andreas; Foken, Thomas; Wirth, Volkmar

2014-07-01

We investigate the evolution of the early-morning boundary layer in a low-mountain valley in south-western Germany during COPS (convective and orographically induced precipitation study) in summer 2007. The term low-mountain refers to a mountainous region with a relief of gentle slopes and with an absolute altitude that remains under a specified height (usually 1,500 m a.s.l.). A subset of 23 fair weather days from the campaign was selected to study the transition of the boundary-layer flow in the early morning. The typical valley atmosphere in the morning hours was characterized by a stable temperature stratification and a pronounced valley wind system. During the reversal period—called the low wind period—of the valley wind system (duration of 1-2 h), the horizontal flow was very weak and the conditions for free convection were fulfilled close to the ground. Ground-based sodar observations of the vertical wind show enhanced values of upward motion, and the corresponding statistical properties differ from those observed under windless convective conditions over flat terrain. Large-eddy simulations of the boundary-layer transition in the valley were conducted, and statistical properties of the simulated flow agree with the observed quantities. Spatially coherent turbulence structures are present in the temporal as well as in the ensemble mean analysis. Thus, the complex orography induces coherent convective structures at predictable, specific locations during the early-morning low wind situations. These coherent updrafts, found in both the sodar observations and the simulation, lead to a flux counter to the gradient of the stably stratified valley atmosphere and reach up to the heights of the surrounding ridges. Furthermore, the energy balance in the surface layer during the low wind periods is closed. However, it becomes unclosed after the onset of the valley wind. The partition into the sensible and the latent heat fluxes indicates that missing flux

Left ventricular diastolic dysfunction without left ventricular hypertrophy in obese children and adolescents: a Tissue Doppler Imaging and Cardiac Troponin I Study.

PubMed

El Saiedi, Sonia A; Mira, Marwa F; Sharaf, Sahar A; Al Musaddar, Maysoun M; El Kaffas, Rania M H; AbdelMassih, Antoine F; Barsoum, Ihab H Y

2018-01-01

Obesity increases the risk for various cardiovascular problems. Increase in body mass index is often an independent risk factor for the development of elevated blood pressure and clustering of various cardiovascular risk factors. To determine early markers of left ventricular affection in obese patients before the appearance of left ventricular hypertrophy. In this cross-sectional study, we evaluated 42 obese patients and 30 healthy controls. Their ages ranged from 6 to 19 years. Studied children were subjected to anthropometric, lipid profile, and serum Troponin I level measurements. Echocardiographic evaluation performed to assess the left ventricle included left ventricular dimension measurement using motion-mode echocardiography, based on which patients with left ventricular hypertrophy (10 patients) were eliminated, as well as conventional and tissue Doppler imaging. Tissue Doppler findings in the study groups showed that the ratio of transmitral early diastolic filling velocity to septal peak early diastolic myocardial velocity (E/e') was significantly higher in cases compared with controls [6.9±1.4 versus 9.0±1.6, p (Pearson's coefficient)=0.001, respectively]. The level of cardiac troponin I was significantly higher in cases compared with controls [0.14±0.39 ng/ml versus 0.01±0.01 ng/ml, p (Pearson's coefficient)=0.047, respectively] and there was a significant correlation between troponin I and transmitral early diastolic filling velocity to septal peak early diastolic myocardial velocity ratio (E/e') [R (correlation coefficient)=0.6]. Tissue Doppler Imaging and Troponin I evaluation proved useful tools to detect early affection of the left ventricle in obese patients even in the absence of left ventricular hypertrophy.

Prediction of early and late preeclampsia by flow-mediated dilation of the brachial artery*

PubMed Central

Brandão, Augusto Henriques Fulgêncio; Evangelista, Aline Aarão; Martins, Raphaela Menin Franco; Leite, Henrique Vítor; Cabral, Antônio Carlos Vieira

2014-01-01

Objective To assess the accuracy in the prediction of both early and late preeclampsia by flow-mediated dilation of the brachial artery (FMD), a biophysical marker for endothelial dysfunction. Materials and Methods A total of 91 patients, considered at high risk for development of preeclampsia were submitted to brachial artery FMD between 24 and 28 weeks of gestation. Results Nineteen out of the selected patients developed preeclampsia, 8 in its early form and 11 in the late form. With a cut-off value of 6.5%, the FMD sensitivity for early preeclampsia prediction was 75.0%, with specificity of 73.3%, positive predictive value (PPV) of 32.4% and negative predictive value (NPV) of 91.9%. For the prediction of late preeclampsia, sensitivity = 83.3%, specificity = 73.2%, PPV = 34.4% and NPV = 96.2% were observed. And for the prediction of all associated forms of preeclampsia, sensitivity = 84.2%, specificity = 73.6%, PPV = 45.7% and NPV = 94.6% were observed. Conclusion FMD of the brachial artery is a test with good accuracy in the prediction of both early and late preeclampsia, which may represent a positive impact on the follow-up of pregnant women at high risk for developing this syndrome. PMID:25741086

The Role of Cash Flow in Financial Early Warning of Agricultural Enterprises Based on Logistic Model

NASA Astrophysics Data System (ADS)

Sun, Fengru

2018-01-01

This paper chooses the agricultural listed companies as the research object, compares the financial situation of the enterprise and the theory of financial early warning, combines the financial status of the agricultural listed companies, selects the relevant cash flow indicators, discusses the application of the Logistic financial early warning model in the agricultural listed companies, Agricultural enterprises get better development. Research on financial early warning of agricultural listed companies will help the agricultural listed companies to predict the financial crisis. Financial early warning model is simple to establish, operational and strong, the use of financial early warning model, to help enterprises in the financial crisis before taking rapid and effective measures, which can avoid losses. Help enterprises to discover signs of deterioration of the financial situation in time to maintain the sustainable development of agricultural enterprises. In addition, through the financial early warning model, investors can correctly identify the financial situation of agricultural enterprises, and can evaluate the financial situation of agricultural enterprises and to help investors to invest in scientific and rational, beneficial to investors to analyze the safety of investment. But also help the relevant regulatory agencies to effectively monitor the market and promote the healthy and stable development of the market.

Left ventricular diastolic dysfunction in type 2 diabetes patients: a novel 2D strain analysis based on cardiac magnetic resonance imaging.

PubMed

Chen, Qiang; Gan, Yan; Li, Zhi-Yong

2016-09-01

This study was to develop a strain analysis method to evaluate the left ventricular (LV) functions in type 2 diabetic patients with an asymptomatic LV diastolic dysfunction. Two groups (10 asymptomatic type 2 diabetic subjects and 10 control ones) were considered. All of the subjects had normal ejection fraction values but impaired diastolic functions assessed by the transmitral blood flow velocity. For each subject, based on cardiac MRI, global indexes including LV volume, LV myocardial mass, cardiac index (CI), and transmitral peak velocity, were measured, and regional indexes (i.e., LV deformation, strain and strain rate) were calculated through an image-registration technology. Most of the global indexes did not differentiate between the two groups, except for the CI, LV myocardial mass and transmitral peak velocity. While for the regional indexes, the global LV diastolic dysfunction of the diabetic indicated an increased strain (0.08 ± 0.044 vs. -0.031 ± 0.077, p = 0.001) and a reduced strain rate (1.834 ± 0.909 vs. 3.791 ± 2.394, p = 0.033) compared to the controls, moreover, the local LV diastolic dysfunction reflected by the strain and strain rate varied, and the degree of dysfunction gradually decreased from the basal level to the apical level. The results showed that the strain and strain rates are effective to capture the subtle alterations of the LV functions, and the proposed method can be used to estimate the LV myocardial function based on cardiac MRI.

Acute changes in pulmonary artery pressures due to exercise and exposure to high altitude do not cause left ventricular diastolic dysfunction.

PubMed

Bernheim, Alain M; Kiencke, Stephanie; Fischler, Manuel; Dorschner, Lorenz; Debrunner, Johann; Mairbäurl, Heimo; Maggiorini, Marco; Brunner-La Rocca, Hans Peter

2007-08-01

Altitude-induced pulmonary hypertension has been suggested to cause left ventricular (LV) diastolic dysfunction due to ventricular interaction. In this study, we evaluate the effects of exercise- and altitude-induced increase in pulmonary artery pressures on LV diastolic function in an interventional setting investigating high-altitude pulmonary edema (HAPE) prophylaxis. Among 39 subjects, 29 were HAPE susceptible (HAPE-S) and 10 served as control subjects. HAPE-S subjects were randomly assigned to prophylactic tadalafil (10 mg), dexamethasone (8 mg), or placebo bid, starting 1 day before ascent. Doppler echocardiography at rest and during submaximal exercise was performed at low altitude (490 m) and high altitude (4,559 m). The ratio of early transmitral inflow peak velocity (E) to atrial transmitral inflow peak velocity (A), pulmonary venous flow parameters, and tissue velocity within the septal mitral annulus during early diastole (E') were used to assess LV diastolic properties. LV filling pressures were estimated by E/E'. Systolic right ventricular to atrial pressure gradients (RVPGs) were measured in order to estimate pulmonary artery pressures. At 490 m, E/A decreased similarly with exercise in HAPE-S and control subjects (HAPE-S, 1.5 +/- 0.3 to 1.3 +/- 0.3; control, 1.7 +/- 0.4 to 1.3 +/- 0.3; p = 0.12 between groups) [mean +/- SD], whereas RVPG increased significantly more in HAPE-S subjects (20 +/- 5 to 43 +/- 9 mm Hg vs 18 +/- 3 to 28 +/- 3 mm Hg, p < 0.001). Changes in RVPG levels during exercise did not correlate with changes in E/A (p > 0.1). From 490 to 4,559 m, no correlations between changes in RVPG and changes in E/A or atrial reversal (both p > 0.1) were observed. Neither of the groups showed an increase in E/E' from 490 to 4,559 m. Increased pulmonary artery pressure associated with exercise and acute exposure to 4,559 m appears not to cause LV diastolic dysfunction in healthy subjects. Therefore, ventricular interaction seems not to be of

Spanwise structure of the flow past a fixed or freely vibrating cylinder in the early turbulent regime

NASA Astrophysics Data System (ADS)

Bourguet, Remi; Gsell, Simon; Braza, Marianna

2017-11-01

The flow patterns developing downstream of slender bodies with bluff cross-section have been the object of intense research in the past decades. Particular attention was paid to the vortex patterns emerging in the plane perpendicular to the body axis. In the present study, focus is placed on the spanwise structure of the flow, in the early turbulent regime. The existence of dominant spanwise wavelengths had already been reported. However, many aspects remained to be explored, among others, the streamwise evolution of the spanwise patterns and their possible alteration when the body oscillates. These aspects are examined here on the basis of direct numerical simulations of the flow past a circular cylinder at Reynolds number 3900. The body is either fixed or subjected to vortex-induced vibrations. A systematic analysis of the spanwise patterns reveals persistent trends of their amplitude and wavelength in the different compartments of the flow, i.e. the separating shear layer and wake regions. Physical mechanisms are proposed to explain these trends. It is also found that the spanwise structure of the flow is differently altered in these two regions once the cylinder vibrates, the alteration being concentrated in the separating shear layers.

Detection of early changes in lung cell cytology by flow-systems analysis techniques

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

Steinkamp, J.A.; Hansen, K.M.; Wilson, J.S.

1976-12-01

This report summarizes results of continuing experiments to develop cytological and biochemical indicators for estimating damage to respiratory cells in test animals exposed by inhalation to toxic agents associated with nonnuclear energy production, the specific goal being the application of advanced multiparameter flow-systems technologies to the detection of early atypical cellular changes in lung epithelium. Normal Syrian hamster lung cell samples composed of macrophages, leukocytes, ciliated columnar cells, and epithelial cells were stained with fluorescent dyes specific for different biochemical parameters and were analyzed in liquid suspension as they flowed through a chamber intersecting a laser beam of exciting light.more » Multiple sensors measured the total or two-color fluorescence and light scatter on a cell-by-cell basis. Cellular parameters proportional to optical measurements (i.e., cell size, DNA content, total protein, nonspecific esterase activity, nuclear and cytoplasmic diameters) were displayed as frequency distribution histograms. Lung cell samples were also separated according to various cytological parameters and identified microscopically. The basic operating features of the methodology are discussed briefly, along with specific examples of preliminary results illustrating the initial characterization of exfoliated pulmonary cells from normal hamsters. As the flow technology is adapted further to the analysis of respiratory cells, measurements of changes in physical and biochemical properties as a function of exposure to toxic agents will be performed.« less

Effect of the prosthetic mitral valve on vortex dynamics and turbulence of the left ventricular flow

NASA Astrophysics Data System (ADS)

Querzoli, G.; Fortini, S.; Cenedese, A.

2010-04-01

Mechanical heart valves implanted in mitral position have a great effect on the ventricular flow. Changes include alteration of the dynamics of the vortical structures generated during the diastole and the onset of turbulence, possibly affecting the efficiency of the heart pump or causing blood cell damage. Modifications to the hemodynamics in the left ventricle, when the inflow through the mitral orifice is altered, were investigated in vitro using a silicone rubber, flexible ventricle model. Velocity fields were measured in space and time by means of an image analysis technique: feature tracking. Three series of experiments were performed: one with a top hat inflow velocity profile (schematically resembling physiological conditions), and two with mechanical prosthetic valves of different design, mounted in mitral position—one monoleaflet and the other bileaflet. In each series of runs, two different cardiac outputs have been examined by changing the stroke volume. The flow was investigated in terms of phase averaged velocity field and second order moments of turbulent fluctuations. Results show that the modifications in the transmitral flow change deeply the interaction between the coherent structures generated during the first phase of the diastole and the incoming jet during the second diastolic phase. Top hat inflow gives the coherent structures which are optimal, among the compared cases, for the systolic function. The flow generated by the bileaflet valve preserves most of the beneficial features of the top hat inflow, whereas the monoleaflet valve generates a strong jet which discourages the permanence of large coherent structures at the end of the diastole. Moreover, the average shear rate magnitudes induced by the smoother flow pattern of the case of top hat inflow are nearly halved in comparison with the values measured with the mechanical valves. Finally, analysis of the turbulence statistics shows that the monoleaflet valves yield higher turbulence

Establishing tools for early diagnosis of congenital toxoplasmosis: Flow cytometric IgG avidity assay as a confirmatory test for neonatal screening.

PubMed

de Castro Zacche-Tonini, Aline; Fonseca, Giuliana Schmidt França; de Jesus, Laura Néspoli Nassar Pansini; Barros, Geisa Baptista; Coelho-Dos-Reis, Jordana Grazziela Alves; Béla, Samantha Ribeiro; Machado, Anderson Silva; Carneiro, Ana Carolina Aguiar Vasconcelos; Andrade, Gláucia Manzan Queiroz; Vasconcelos-Santos, Daniel Vitor; Januário, José Nélio; Teixeira-Carvalho, Andréa; Vitor, Ricardo Wagner Almeida; Ferro, Eloísa Amália Vieira; Mineo, José Roberto; Martins-Filho, Olindo Assis; Lemos, Elenice Moreira

2017-12-01

The aim of this study was to evaluate the performance of conventional serology (Q-Preven™ and ELFAVIDAS™) and flow cytometry-based serologic tools for early serologic diagnosis of congenital toxoplasmosis. The study groups included prospectively confirmed cases of congenital toxoplasmosis (TOXO=88) and age-matching non-infected controls (NI=15).The results demonstrated that all samples tested positive/indeterminate for anti-T. gondii IgM screening at birth using air-dried whole blood samples. Serum samples collected at 30-45days after birth tested positive for ELFAVIDAS™ IgG in both groups. While all NI tested negative for ELFAVIDAS™ IgM and IgA, only 78% and 36% of TOXO tested positive for IgM and IgA, respectively. Flow cytometry-based anti-T. gondii IgM, IgA and IgG reactivity displayed moderate performance with low sensitivity (47.6%, 72.6% and 75.0%, respectively). Regardless the remarkable specificity of IgG1, IgG2 and IgG3 subclasses for early diagnosis, weak or moderate specificity was observed (Se=73.9%, 60.2% and 83.0%, respectively). The analysis of IgG avidity indices (AI) demonstrated the highest performance among the flow cytometry-based methods (Se=96.6%; Sp=93.3%), underscoring the low avidity index (AI<60%) within TOXO (97.0%) in contrast with the high avidity index (AI>60%) in NI (93%). Analysis of anti-T. gondii IgG and IgG3 reactivity for mother:infant paired samples may represent a relevant complementary tests for early diagnosis. In conclusion, a feasible high-standard algorithm (Accuracy=97.1%) was proposed consisting of Q-Preven™ IgM screening at birth, followed by ELFAVIDAS™ IgM and flow cytometric IgG avidity analysis at 30-45days after birth as a high performance tool for early serological diagnosis of congenital toxoplasmosis. Copyright © 2017. Published by Elsevier B.V.

Detection of early changes in lung cell cytology by flow-systems analysis techniques, July 1--December 31, 1975

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

Steinkamp, J.A.; Ingram, M.; Hansen, K.M.

1976-03-01

This report summarizes results of preliminary experiments to demonstrate the feasibility of using automated flow-systems analysis in detecting early changes of respiratory epithelium exposed to physical and chemical agents associated with the by-products of nonnuclear energy production. The Syrian hamster was selected as the experimental test animal to begin investigation of the effects of toxic agents to cells of the respiratory tract. Since initiation of the program approximately six months ago, the goals have been acquisition of adequate numbers of exfoliated cells from the lung; adaptation of cytological techniques developed on human exfoliated gynecological samples to hamster lung epithelium formore » obtaining single-cell suspensions; utilization of existing cell staining methods to measure DNA content in lung cells; and analysis of DNA content and cell size. As the flow-system cell analysis technology is adapted to the measurement of exfoliated lung cells, rapid and quantitative determination of early changes in the physical and biochemical cellular properties will be attempted as a function of exposure to the toxic agents. (auth)« less

Pulmonary venous flows reflect changes in left atrial hemodynamics during mitral balloon valvotomy.

PubMed

Yalçin, Fatih; El-Amrousy, Mahmoud; Müderrisoğlu, Haldun; Korkmaz, Mehmet; Flachskampf, Frank; Tuzcu, Murat; Garcia, Mario G; Thomas, James D

2002-01-01

Patients with mitral stenosis have usually blunted pulmonary venous (PV) flow, because of decreased mitral valve area and diastolic dysfunction. The authors compared changes in Doppler PV velocities by using transesophageal echocardiography (TEE) against hemodynamics parameters before and after mitral balloon valvotomy to observe relevance of PV velocities and endsystolic left atrial (LA) pressure-volume relationship. In 25 patients (aged 35 +/- 17 years) with mitral stenosis in sinus rhythm, changes in LA pressure and volumes were compared with PV velocities before and after valvotomy. Mitral valve area, mitral gradients, and deceleration time were obtained. Mitral valve area and mitral gradients changed from 1 +/- 0.2 cm2 and 14.6 +/- 5.4 mmHg to 1.9 +/- 0.3 cm2 and 6.3 +/- 1.7 mmHg, respectively (p<0.001). AR peak reverse flow velocity and AR duration decreased from 29 +/- 13 cm/s and 110 =/- 30 msec to 19 +/- 6 cm/s and 80 +/- 29 msec respectively (p<0.001). Transmitral Doppler E wave deceleration time decreased from 327 +/- 85 to 209 +/- 61 s and cardiac output increased from 4.2 +/- 1.0 to 5.2 +/- 1.1 L/minute (p<0.001). The changes in LA pressure were correlated with changes in S/D (r=0.57, p<0.05). The changes in endsystolic LA pressure-volume relationship were also correlated with changes in S/D (r=0.52, p<0.05). Endsystolic LA pressure-volume relationship decreased after mitral balloon valvotomy, as a result of a large decrease in pressure. PV systolic/diastolic (S/D) waves ratio reflects endsystolic LA pressure-volume relationship and may be used as another indicator of successful valvotomy.

Pulmonary venous flows reflect changes in left atrial hemodynamics during mitral balloon valvotomy

NASA Technical Reports Server (NTRS)

Yalcin, Fatih; El-Amrousy, Mahmoud; Muderrisoglu, Haldun; Korkmaz, Mehmet; Flachskampf, Frank; Tuzcu, Murat; Garcia, Mario G.; Thomas, James D.

2002-01-01

Patients with mitral stenosis have usually blunted pulmonary venous (PV) flow, because of decreased mitral valve area and diastolic dysfunction. The authors compared changes in Doppler PV velocities by using transesophageal echocardiography (TEE) against hemodynamics parameters before and after mitral balloon valvotomy to observe relevance of PV velocities and endsystolic left atrial (LA) pressure-volume relationship. In 25 patients (aged 35 +/- 17 years) with mitral stenosis in sinus rhythm, changes in LA pressure and volumes were compared with PV velocities before and after valvotomy. Mitral valve area, mitral gradients, and deceleration time were obtained. Mitral valve area and mitral gradients changed from 1 +/- 0.2 cm2 and 14.6 +/- 5.4 mmHg to 1.9 +/- 0.3 cm2 and 6.3 +/- 1.7 mmHg, respectively (p<0.001). AR peak reverse flow velocity and AR duration decreased from 29 +/- 13 cm/s and 110 =/- 30 msec to 19 +/- 6 cm/s and 80 +/- 29 msec respectively (p<0.001). Transmitral Doppler E wave deceleration time decreased from 327 +/- 85 to 209 +/- 61 s and cardiac output increased from 4.2 +/- 1.0 to 5.2 +/- 1.1 L/minute (p<0.001). The changes in LA pressure were correlated with changes in S/D (r=0.57, p<0.05). The changes in endsystolic LA pressure-volume relationship were also correlated with changes in S/D (r=0.52, p<0.05). Endsystolic LA pressure-volume relationship decreased after mitral balloon valvotomy, as a result of a large decrease in pressure. PV systolic/diastolic (S/D) waves ratio reflects endsystolic LA pressure-volume relationship and may be used as another indicator of successful valvotomy.

Early turbulence in von Karman swirling flow of polymer solutions

NASA Astrophysics Data System (ADS)

Burnishev, Yuri; Steinberg, Victor

2015-01-01

We present quantitative experimental results on the transition to early turbulence in von Karman swirling flow of water- and water-sugar-based polymer solutions compared to the transition to turbulence in their Newtonian solvents by measurements of solely global quantities as torque Γ(t) and pressure p(t) with large statistics as a function of Re. For the first time the transition values of Re_c\\textit{turb} to fully developed turbulence and turbulent drag reduction regime Re_c\\textit{TDR} are obtained as functions of elasticity El by using the solvents with different viscosities and polymer concentrations ϕ. Two scaling regions for fundamental turbulent characteristics are identified and they correspond to the turbulent and TDR regimes. Both Re_c\\textit{turb} and Re_c\\textit{TDR} are found via the dependence of the friction coefficient Cf and Cp, defined through scaled average torque \\barΓ and rms pressure fluctuations p\\textit{rms} , respectively, on Re for different El and ϕ and via the limits of the two scaling regions.

Flow banding in basaltic pillow lavas from the Early Archean Hooggenoeg Formation, Barberton Greenstone Belt, South Africa

NASA Astrophysics Data System (ADS)

Robins, Brian; Sandstå, Nils Rune; Furnes, Harald; de Wit, Maarten

2010-07-01

Well-preserved pillow lavas in the uppermost part of the Early Archean volcanic sequence of the Hooggenoeg Formation in the Barberton Greenstone Belt exhibit pronounced flow banding. The banding is defined by mm to several cm thick alternations of pale green and a dark green, conspicuously variolitic variety of aphyric metabasalt. Concentrations of relatively immobile TiO2, Al2O3 and Cr in both varieties of lava are basaltic. Compositional differences between bands and variations in the lavas in general have been modified by alteration, but indicate mingling of two different basalts, one richer in TiO2, Al2O3, MgO, FeOt and probably Ni and Cr than the other, as the cause of the banding. The occurrence in certain pillows of blebs of dark metabasalt enclosed in pale green metabasalt, as well as cores of faintly banded or massive dark metabasalt, suggest that breakup into drops and slugs in the feeder channel to the lava flow initiated mingling. The inhomogeneous mixture was subsequently stretched and folded together during laminar shear flow through tubular pillows, while diffusion between bands led to partial homogenisation. The most common internal pattern defined by the flow banding in pillows is concentric. In some pillows the banding defines curious mushroom-like structures, commonly cored by dark, variolitic metabasalt, which we interpret as the result of secondary lateral flow due to counter-rotating, transverse (Dean) vortices induced by the axial flow of lava towards the flow front through bends, generally downward, in the tubular pillows. Other pillows exhibit weakly-banded or massive, dark, variolitic cores that are continuous with wedge-shaped apophyses and veins that intrude the flow banded carapace. These cores represent the flow of hotter and less viscous slugs of the dark lava type into cooled and stiffened pillows.

Echocardiographic assessment of left ventricular diastolic function.

PubMed

Pirat, Bahar; Zoghbi, William A

2007-09-01

Assessment of diastolic function and left ventricular filling pressures in the setting of both normal and reduced systolic function is of major importance particularly in patients with dyspnea. Since multiple echocardiography parameters are used to assess diastolic function each with some limitations, a comprehensive approach should be applied. Transmitral Doppler flow should be evaluated in combination with newer, less load dependent Doppler techniques. Tissue Doppler imaging provides accurate, well validated data regarding diastolic properties and filling pressures of the left ventricle. Tissue Doppler imaging should be the part of a routine echocardiography study due to its ease of use and high reproducibility. Pulmonary vein Doppler and flow propagation velocity should be incorporated into the evaluation when needed.

Doppler indexes of left ventricular systolic and diastolic flow and central pulse pressure in relation to renal resistive index.

PubMed

Kuznetsova, Tatiana; Cauwenberghs, Nicholas; Knez, Judita; Thijs, Lutgarde; Liu, Yan-Ping; Gu, Yu-Mei; Staessen, Jan A

2015-04-01

The cardio-renal interaction occurs via hemodynamic and humoral factors. Noninvasive assessment of renal hemodynamics is currently possible by assessment of renal resistive index (RRI) derived from intrarenal Doppler arterial waveforms as ((peak systolic velocity - end-diastolic velocity)/peak systolic velocity). Limited information is available regarding the relationship between RRI and cardiac hemodynamics. We investigated these associations in randomly recruited subjects from a general population. In 171 participants (48.5% women; mean age, 52.2 years), using pulsed wave Doppler, we measured RRI (mean, 0.60) and left ventricular outflow tract (LVOT) and transmitral (E and A) blood flow peak velocities and its velocity time integrals (VTI). Using carotid applanation tonometry, we measured central pulse pressure and arterial stiffness indexes such as augmentation pressure and carotid-femoral pulse wave velocity. In stepwise regression analysis, RRI independently and significantly increased with female sex, age, body weight, brachial pulse pressure, and use of β-blockers, whereas it decreased with body height and mean arterial pressure. In multivariable-adjusted models with central pulse pressure and arterial stiffness indexes as the explanatory variables, we observed a significant and positive correlation of RRI only with central pulse pressure (P < 0.0001). Among the Doppler indexes of left ventricular blood flow, RRI was significantly and positively associated with LVOT and E peak velocities (P ≤ 0.012) and VTIs (P ≤ 0.010). We demonstrated that in unselected subjects RRI was significantly associated with central pulse pressure and left ventricular systolic and diastolic Doppler blood flow indexes. Our findings imply that in addition to the anthropometric characteristics, cardiac hemodynamic factors influence the intrarenal arterial Doppler waveform patterns. © American Journal of Hypertension, Ltd 2014. All rights reserved. For Permissions, please email

Respiratory flows during early childhood: Computational models to examine therapeutic aerosols in the developing airways

NASA Astrophysics Data System (ADS)

Tenenbaum-Katan, Janna; Hofemeier, Philipp; Sznitman, Josué; Janna Tenenbaum-Katan Team

2015-11-01

Inhalation therapy is the cornerstone of early-childhood respiratory treatments, as well as a rising potential for systemic drug delivery and pulmonary vaccination. As such, indispensable understanding of respiratory flow phenomena, coupled with particle transport at the deep regions of children's lungs is necessary to attain efficient targeting of aerosol therapy. However, fundamental research of pulmonary transport is overwhelmingly focused on adults. In our study, we have developed an anatomically-inspired computational model of representing pulmonary acinar regions at several age points during a child's development. Our numerical simulations examine respiratory flows and particle deposition maps within the acinar model, accounting for varying age dependant anatomical considerations and ventilation patterns. Resulting deposition maps of aerosols alter with age, such findings might suggest that medication protocols of inhalation therapy in young children should be considered to be accordingly amended with the child's development. Additionally to understanding basic scientific concepts of age effects on aerosol deposition, our research can potentially contribute practical guidelines to therapy protocols, and its' necessary modifications with age. We acknowledge the support of the ISF and the Israeli ministry of Science.

Prognostic value of systolic mitral annular velocity measured with Doppler tissue imaging in patients with chronic heart failure caused by left ventricular systolic dysfunction

PubMed Central

Nikitin, N P; Loh, P H; de Silva, R; Ghosh, J; Khaleva, O Y; Goode, K; Rigby, A S; Alamgir, F; Clark, A L; Cleland, J G F

2006-01-01

Objective To assess the prognostic value of various conventional and novel echocardiographic indices in patients with chronic heart failure (CHF) caused by left ventricular (LV) systolic dysfunction. Methods 185 patients with a mean (SD) age of 67 (11) years with CHF and LV ejection fraction < 45% despite optimal pharmacological treatment were prospectively enrolled. The patients underwent two dimensional echocardiography with tissue harmonic imaging to assess global LV systolic function and obtain volumetric data. Transmitral flow was assessed with conventional pulse wave Doppler. Systolic (Sm), early, and late diastolic mitral annular velocities were measured with the use of colour coded Doppler tissue imaging. Results During a median follow up of 32 months (range 24–38 months in survivors), 34 patients died and one underwent heart transplantation. Sm velocity (hazard ratio (HR) 0.648, 95% confidence interval (CI) 0.463 to 0.907, p  =  0.011), diastolic arterial pressure (HR 0.965, 95% CI 0.938 to 0.993, p  =  0.015), serum creatinine (HR 1.006, 95% CI 1.001 to 1.011, p  =  0.023), LV ejection fraction (HR 0.945, 95% CI 0.899 to 0.992, p  =  0.024), age (HR 1.035, 95% CI 1.000 to 1.071, p  =  0.052), LV end systolic volume index (HR 1.009, 95% CI 0.999 to 1.019, p  =  0.067), and restrictive pattern of transmitral flow (HR 0.543, 95% CI 0.278 to 1.061, p  =  0.074) predicted the outcome of death or transplantation on univariate analysis. On multivariate analysis, only Sm velocity (HR 0.648, 95% CI 0.460 to 0.912, p  =  0.013) and diastolic arterial pressure (HR 0.966, 95% CI 0.938 to 0.994, p  =  0.016) emerged as independent predictors of outcome. Conclusions In patients with CHF and LV systolic dysfunction despite optimal pharmacological treatment, the strongest independent echocardiographic predictor of prognosis was Sm velocity measured with quantitative colour coded Doppler tissue

Dynamic flow modeling of riverine amphibian habitat with application to regulated flow management

Treesearch

S. Yarnell; A. Lind; J. Mount

2012-01-01

In regulated rivers, relicensing of hydropower projects can provide an opportunity to change flow regimes and reduce negative effects on sensitive aquatic biota. The volume of flow, timing and ramping rate of spring spills, and magnitude of aseasonal pulsed flows have potentially negative effects on the early life stages of amphibians, such as the Foothill yellow-...

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.

Early Cretaceous terrestrial ecosystems in East Asia based on food-web and energy-flow models

USGS Publications Warehouse

Matsukawa, M.; Saiki, K.; Ito, M.; Obata, I.; Nichols, D.J.; Lockley, M.G.; Kukihara, R.; Shibata, K.

2006-01-01

In recent years, there has been global interest in the environments and ecosystems around the world. It is helpful to reconstruct past environments and ecosystems to help understand them in the present and the future. The present environments and ecosystems are an evolving continuum with those of the past and the future. This paper demonstrates the contribution of geology and paleontology to such continua. Using fossils, we can make an estimation of past population density as an ecosystem index based on food-web and energy-flow models. Late Mesozoic nonmarine deposits are distributed widely on the eastern Asian continent and contain various kinds of fossils such as fishes, amphibians, reptiles, dinosaurs, mammals, bivalves, gastropods, insects, ostracodes, conchostracans, terrestrial plants, and others. These fossil organisms are useful for late Mesozoic terrestrial ecosystem reconstruction using food-web and energy-flow models. We chose Early Cretaceous fluvio-lacustrine basins in the Choyr area, southeastern Mongolia, and the Tetori area, Japan, for these analyses and as a potential model for reconstruction of other similar basins in East Asia. The food-web models are restored based on taxa that occurred in these basins. They form four or five trophic levels in an energy pyramid consisting of rich primary producers at its base and smaller biotas higher in the food web. This is the general energy pyramid of a typical ecosystem. Concerning the population densities of vertebrate taxa in 1 km2 in these basins, some differences are recognized between Early Cretaceous and the present. For example, Cretaceous estimates suggest 2.3 to 4.8 times as many herbivores and 26.0 to 105.5 times the carnivore population. These differences are useful for the evaluation of past population densities of vertebrate taxa. Such differences may also be caused by the different metabolism of different taxa. Preservation may also be a factor, and we recognize that various problems occur in

Abnormal early diastolic intraventricular flow 'kinetic energy index' assessed by vector flow mapping in patients with elevated filling pressure.

PubMed

Nogami, Yoshie; Ishizu, Tomoko; Atsumi, Akiko; Yamamoto, Masayoshi; Kawamura, Ryo; Seo, Yoshihiro; Aonuma, Kazutaka

2013-03-01

Recently developed vector flow mapping (VFM) enables evaluation of local flow dynamics without angle dependency. This study used VFM to evaluate quantitatively the index of intraventricular haemodynamic kinetic energy in patients with left ventricular (LV) diastolic dysfunction and to compare those with normal subjects. We studied 25 patients with estimated high left atrial (LA) pressure (pseudonormal: PN group) and 36 normal subjects (control group). Left ventricle was divided into basal, mid, and apical segments. Intraventricular haemodynamic energy was evaluated in the dimension of speed, and it was defined as the kinetic energy index. We calculated this index and created time-energy index curves. The time interval from electrocardiogram (ECG) R wave to peak index was measured, and time differences of the peak index between basal and other segments were defined as ΔT-mid and ΔT-apex. In both groups, early diastolic peak kinetic energy index in mid and apical segments was significantly lower than that in the basal segment. Time to peak index did not differ in apex, mid, and basal segments in the control group but was significantly longer in the apex than that in the basal segment in the PN group. ΔT-mid and ΔT-apex were significantly larger in the PN group than the control group. Multiple regression analysis showed sphericity index, E/E' to be significant independent variables determining ΔT apex. Retarded apical kinetic energy fluid dynamics were detected using VFM and were closely associated with LV spherical remodelling in patients with high LA pressure.

Association between left atrial phasic conduit function and early atrial fibrillation recurrence in patients undergoing electrical cardioversion.

PubMed

Degiovanni, Anna; Boggio, Enrico; Prenna, Eleonora; Sartori, Chiara; De Vecchi, Federica; Marino, Paolo N

2018-04-01

Diastolic dysfunction promotes atrial fibrillation (AF) inducing left atrial (LA) remodeling, with chamber dilation and fibrosis. Predominance of LA phasic conduit (LAC) function should reflect not only chamber alterations but also underlying left ventricular (LV) filling impairment. Thus, LAC was tested as possible predictor of early AF relapse after electrical cardioversion (EC). 96 consecutive patients, who underwent EC for persistent non-valvular AF, were prospectively enrolled. Immediately after successful EC (3 h ± 15 min), an echocardiographic apical four-chamber view was acquired with transmitral velocities, annular tissue Doppler and simultaneous LV and LA three-dimensional full-volume datasets. Then, from LA-LV volumetric curves we computed LAC as: [(LV maximum - LV minimum) - (LA maximum - LA minimum) volume], expressed as % LV stroke volume. LA pump, immediately post-EC, was assumed and verified as being negligible. Sinus rhythm persistence at 1 month was checked with ECG-Holter monitoring. At 1 month 62 patients were in sinus rhythm and 34 in AF. AF patients presented pre-EC higher E/é values (p = 0.012), no major LA volume differences (p = NS), but a stiffer LV cavity (p = 0.012) for a comparable LV capacitance (p = 0.461). Conduit contributed more (p < 0.001) to LV stroke volume in AF subpopulation. Multiple regression revealed LAC as the most significant AF predictor (p = 0.013), even after correction for biometric characteristics and pharmacotherapy (p = 0.008). Our data suggest that LAC larger contribution to LV filling soon after EC reflects LA-LV stiffening, which skews atrioventricular interaction leading to AF perpetuation and makes conduit dominance a powerful predictor of early AF recurrence.

Echocardiographic Assessment of Degenerative Mitral Stenosis: A Diagnostic Challenge of an Emerging Cardiac Disease.

PubMed

Oktay, Ahmet Afşşin; Gilliland, Yvonne E; Lavie, Carl J; Ramee, Stephen J; Parrino, Patrick E; Bates, Michael; Shah, Sangeeta; Cash, Michael E; Dinshaw, Homeyar; Qamruddin, Salima

2017-03-01

Degenerative mitral stenosis (DMS) is characterized by decreased mitral valve (MV) orifice area and increased transmitral pressure gradient due to chronic noninflammatory degeneration and subsequent calcification of the fibrous mitral annulus and the MV leaflets. The "true" prevalence of DMS in the general population is unknown. DMS predominantly affects elderly individuals, many of whom have multiple other comorbidities. Transcatheter MV replacement techniques, although their long-term outcomes are yet to be tested, have been gaining popularity and may emerge as more effective and relatively safer treatment option for patients with DMS. Echocardiography is the primary imaging modality for evaluation of DMS and related hemodynamic abnormalities such as increased transmitral pressure gradient and pulmonary arterial pressure. Classic echocardiographic techniques used for evaluation of mitral stenosis (pressure half time, proximal isovelocity surface area, continuity equation, and MV area planimetry) lack validation for DMS. Direct planimetry with 3-dimensional echocardiography and color flow Doppler is a reasonable technique for determining MV area in DMS. Cardiac computed tomography is an essential tool for planning potential interventions or surgeries for DMS. This article reviews the current concepts on mitral annular calcification and its role in DMS. We then discuss the epidemiology, natural history, differential diagnosis, mechanisms, and echocardiographic assessment of DMS. Copyright © 2017 Elsevier Inc. All rights reserved.

Permafrost thaw in a nested groundwater-flow system

USGS Publications Warehouse

McKenzie, Jeffery M.; Voss, Clifford I.

2013-01-01

Groundwater flow in cold regions containing permafrost accelerates climate-warming-driven thaw and changes thaw patterns. Simulation analyses of groundwater flow and heat transport with freeze/thaw in typical cold-regions terrain with nested flow indicate that early thaw rate is particularly enhanced by flow, the time when adverse environmental impacts of climate-warming-induced permafrost loss may be severest. For the slowest climate-warming rate predicted by the Intergovernmental Panel on Climate Change (IPCC), once significant groundwater flow begins, thick permafrost layers can vanish in several hundred years, but survive over 1,000 years where flow is minimal. Large-scale thaw depends mostly on the balance of heat advection and conduction in the supra-permafrost zone. Surface-water bodies underlain by open taliks allow slow sub-permafrost flow, with lesser influence on regional thaw. Advection dominance over conduction depends on permeability and topography. Groundwater flow around permafrost and flow through permafrost impact thaw differently; the latter enhances early thaw rate. Air-temperature seasonality also increases early thaw. Hydrogeologic heterogeneity and topography strongly affect thaw rates/patterns. Permafrost controls the groundwater/surface-water-geomorphology system; hence, prediction and mitigation of impacts of thaw on ecology, chemical exports and infrastructure require improved hydrogeology/permafrost characterization and understanding

Analysis of serial coronary artery flow patterns early after primary angioplasty: new insights into the dynamics of the microcirculation.

PubMed

Sharif, Dawod; Rofe, Guy; Sharif-Rasslan, Amal; Goldhammer, Ehud; Makhoul, Nabeel; Shefer, Arie; Hassan, Amin; Rauchfleisch, Shmuel; Rosenschein, Uri

2008-06-01

The temporal behavior of the coronary microcirculation in acute myocardial infarction may affect outcome. Diastolic deceleration time and early systolic flow reversal derived from coronary artery blood flow velocity patterns reflect microcirculatory function. To assess left anterior descending coronary artery flow velocity patterns using Doppler transthoracic echocardiography after primary percutaneous coronary intervention, in patients with anterior AMI. Patterns of flow velocity patterns of the LAD were obtained using transthoracic echocardiography-Doppler in 31 consecutive patients who presented with anterior AMI. Measurements were done at 6 hours, 36-48 hours, and 5 days after successful PPCI. Measurements of DDT and pressure half times (Pt%), as well as observation for ESFR were performed. In the first 2 days following PPCI, the average DDT (600 +/- 340 msec) was shorter than on day 5 (807 +/- 332 msec) (P < 0.012), FVP in the first 2 days were dynamic and bidirectional: from short DDT (< 600 msec) to long DDT (> 600 msec) and vice versa. On day 5 most DDTs became longer. Pt1/2 at 6 hours was not different than at day 2 (174 +/- 96 vs. 193 +/- 99 msec, P = NS) and became longer on day 5 (235 +/- 98 msec, P = 0.012). Bidirectional patterns were also observed in the ESFR in 6 patients (19%) at baseline, in 4 (13%) at 36 hours, and in 2 (6.5%) on day 5 after PPCI. Flow velocity patterns of the LAD after PPCI in AMI are dynamic and reflect unpredictable changes in microcirculation.

High-purity flow sorting of early meiocytes based on DNA analysis of guinea pig spermatogenic cells.

PubMed

Rodríguez-Casuriaga, Rosana; Geisinger, Adriana; Santiñaque, Federico F; López-Carro, Beatriz; Folle, Gustavo A

2011-08-01

Mammalian spermatogenesis is still nowadays poorly understood at the molecular level. Testis cellular heterogeneity is a major drawback for spermatogenic gene expression studies, especially when research is focused on stages that are usually very short and poorly represented at the cellular level such as initial meiotic prophase I (i.e., leptotene [L] and zygotene [Z]). Presumably, genes whose products are involved in critical meiotic events such as alignment, pairing and recombination of homologous chromosomes are expressed during the short stages of early meiotic prophase. Aiming to characterize mammalian early meiotic gene expression, we have found the guinea pig (Cavia porcellus) as an especially attractive model. A detailed analysis of its first spermatogenic wave by flow cytometry (FCM) and optical microscopy showed that guinea pig testes exhibit a higher representation of early meiotic stages compared to other studied rodents, partly because of their longer span, and also as a result of the increased number of cells entering meiosis. Moreover, we have found that adult guinea pig testes exhibit a peculiar 4C DNA content profile, with a bimodal peak for L/Z and P spermatocytes that is absent in other rodents. Besides, we show that this unusual 4C peak allows the separation by FCM of highly pure L/Z spermatocyte populations aside from pachytene ones, even from adult individuals. To our knowledge, this is the first report on an accurate and suitable method for highly pure early meiotic prophase cell isolation from adult mammals, and thus sets an interesting approach for gene expression studies aiming at a deeper understanding of the molecular groundwork underlying male gamete production. Copyright © 2011 International Society for Advancement of Cytometry.

Machine-Learning Algorithms to Automate Morphological and Functional Assessments in 2D Echocardiography.

PubMed

Narula, Sukrit; Shameer, Khader; Salem Omar, Alaa Mabrouk; Dudley, Joel T; Sengupta, Partho P

2016-11-29

Machine-learning models may aid cardiac phenotypic recognition by using features of cardiac tissue deformation. This study investigated the diagnostic value of a machine-learning framework that incorporates speckle-tracking echocardiographic data for automated discrimination of hypertrophic cardiomyopathy (HCM) from physiological hypertrophy seen in athletes (ATH). Expert-annotated speckle-tracking echocardiographic datasets obtained from 77 ATH and 62 HCM patients were used for developing an automated system. An ensemble machine-learning model with 3 different machine-learning algorithms (support vector machines, random forests, and artificial neural networks) was developed and a majority voting method was used for conclusive predictions with further K-fold cross-validation. Feature selection using an information gain (IG) algorithm revealed that volume was the best predictor for differentiating between HCM ands. ATH (IG = 0.24) followed by mid-left ventricular segmental (IG = 0.134) and average longitudinal strain (IG = 0.131). The ensemble machine-learning model showed increased sensitivity and specificity compared with early-to-late diastolic transmitral velocity ratio (p < 0.01), average early diastolic tissue velocity (e') (p < 0.01), and strain (p = 0.04). Because ATH were younger, adjusted analysis was undertaken in younger HCM patients and compared with ATH with left ventricular wall thickness >13 mm. In this subgroup analysis, the automated model continued to show equal sensitivity, but increased specificity relative to early-to-late diastolic transmitral velocity ratio, e', and strain. Our results suggested that machine-learning algorithms can assist in the discrimination of physiological versus pathological patterns of hypertrophic remodeling. This effort represents a step toward the development of a real-time, machine-learning-based system for automated interpretation of echocardiographic images, which may help novice readers with

Classification of volcanoes of the Kane Patera Quadrangle of Io: Proportions of lava flows and pyroclastic flows

NASA Technical Reports Server (NTRS)

Elston, W. E.

1984-01-01

Voyager 1 images show 14 volcanic centers wholly or partly within the Kane Patera quadrangle of Io, which are divided into four major classes: (1) shield with parallel flows; (2) shield with early radial fan shapd flows; (3) shield with radial fan shaped flows, surfaces of flows textured with longitudinal ridges; and (4) depression surrounded by plateau-forming scarp-bounded, untextured deposits. The interpretation attempted here hinges largely on the ability to distinguish lava flows from pyroclastic flows by remote sensing.

Early regimes of water capillary flow in slit silica nanochannels.

PubMed

Oyarzua, Elton; Walther, Jens H; Mejía, Andrés; Zambrano, Harvey A

2015-06-14

Molecular dynamics simulations are conducted to investigate the initial stages of spontaneous imbibition of water in slit silica nanochannels surrounded by air. An analysis is performed for the effects of nanoscopic confinement, initial conditions of liquid uptake and air pressurization on the dynamics of capillary filling. The results indicate that the nanoscale imbibition process is divided into three main flow regimes: an initial regime where the capillary force is balanced only by the inertial drag and characterized by a constant velocity and a plug flow profile. In this regime, the meniscus formation process plays a central role in the imbibition rate. Thereafter, a transitional regime takes place, in which, the force balance has significant contributions from both inertia and viscous friction. Subsequently, a regime wherein viscous forces dominate the capillary force balance is attained. Flow velocity profiles identify the passage from an inviscid flow to a developing Poiseuille flow. Gas density profiles ahead of the capillary front indicate a transient accumulation of air on the advancing meniscus. Furthermore, slower capillary filling rates computed for higher air pressures reveal a significant retarding effect of the gas displaced by the advancing meniscus.

Quantitative analysis of aortic regurgitation: real-time 3-dimensional and 2-dimensional color Doppler echocardiographic method--a clinical and a chronic animal study

NASA Technical Reports Server (NTRS)

Shiota, Takahiro; Jones, Michael; Tsujino, Hiroyuki; Qin, Jian Xin; Zetts, Arthur D.; Greenberg, Neil L.; Cardon, Lisa A.; Panza, Julio A.; Thomas, James D.

2002-01-01

BACKGROUND: For evaluating patients with aortic regurgitation (AR), regurgitant volumes, left ventricular (LV) stroke volumes (SV), and absolute LV volumes are valuable indices. AIM: The aim of this study was to validate the combination of real-time 3-dimensional echocardiography (3DE) and semiautomated digital color Doppler cardiac flow measurement (ACM) for quantifying absolute LV volumes, LVSV, and AR volumes using an animal model of chronic AR and to investigate its clinical applicability. METHODS: In 8 sheep, a total of 26 hemodynamic states were obtained pharmacologically 20 weeks after the aortic valve noncoronary (n = 4) or right coronary (n = 4) leaflet was incised to produce AR. Reference standard LVSV and AR volume were determined using the electromagnetic flow method (EM). Simultaneous epicardial real-time 3DE studies were performed to obtain LV end-diastolic volumes (LVEDV), end-systolic volumes (LVESV), and LVSV by subtracting LVESV from LVEDV. Simultaneous ACM was performed to obtain LVSV and transmitral flows; AR volume was calculated by subtracting transmitral flow volume from LVSV. In a total of 19 patients with AR, real-time 3DE and ACM were used to obtain LVSVs and these were compared with each other. RESULTS: A strong relationship was found between LVSV derived from EM and those from the real-time 3DE (r = 0.93, P <.001, mean difference (3D - EM) = -1.0 +/- 9.8 mL). A good relationship between LVSV and AR volumes derived from EM and those by ACM was found (r = 0.88, P <.001). A good relationship between LVSV derived from real-time 3DE and that from ACM was observed (r = 0.73, P <.01, mean difference = 2.5 +/- 7.9 mL). In patients, a good relationship between LVSV obtained by real-time 3DE and ACM was found (r = 0.90, P <.001, mean difference = 0.6 +/- 9.8 mL). CONCLUSION: The combination of ACM and real-time 3DE for quantifying LV volumes, LVSV, and AR volumes was validated by the chronic animal study and was shown to be clinically applicable.

Aircraft Laminar Flow Control

NASA Technical Reports Server (NTRS)

Joslin, Ronald D.

1998-01-01

Aircraft laminar flow control (LFC) from the 1930's through the 1990's is reviewed and the current status of the technology is assessed. Examples are provided to demonstrate the benefits of LFC for subsonic and supersonic aircraft. Early studies related to the laminar boundary-layer flow physics, manufacturing tolerances for laminar flow, and insect-contamination avoidance are discussed. LFC concept studies in wind-tunnel and flight experiments are the major focus of the paper. LFC design tools are briefly outlined for completeness.

Benzene-induced myelotoxicity: application of flow cytofluorometry for the evaluation of early proliferative change in bone marrow.

PubMed Central

Irons, R D

1981-01-01

A detailed description of flow cytofluorometric DNA cell cycle analysis is presented. A number of studies by the author and other investigators are reviewed in which a method is developed for the analysis of cell cycle phase in bone marrow of experimental animals. Bone marrow cell cycle analysis is a sensitive indicator of changes in bone marrow proliferative activity occurring early in chemically-induced myelotoxicity. Cell cycle analysis, used together with other hematologic methods, has revealed benzene-induced toxicity in proliferating bone marrow cells to be cycle specific, appearing to affect a population in late S phase which then accumulate in G2/M. PMID:7016521

Analysis of peripheral blood lymphocytes using flow cytometry in polymyalgia rheumatica, RS3PE and early rheumatoid arthritis.

PubMed

Shimojima, Y; Matsuda, M; Ishii, W; Gono, T; Ikeda, S

2008-01-01

Clinical pictures of poly-myalgia rheumatica (PMR) and remitting seronegative symmetrical synovitis with pitting edema (RS3PE) are often indistinguishable from those of early rheumatoid arthritis (RA). To investigate whether there is a difference in immunological aspects among these 3 disorders, we performed a phenotypic analysis of peripheral blood lymphocytes. Eleven patients with early RA, 14 with PMR and 11 with RS3PE were enrolled in this study. After separation of mononuclear cells from peripheral blood using the Ficoll-Hypaque method, surface markers and intracellular cytokines of lymphocytes were analyzed by 2- or 3-color flow cytometry. Both PMR and RS3PE showed a significant decrease in CD8⁺CD25⁺ cells (p<0.05), and significant increases in CD4⁺IFN-gamma⁺IL-4- (p<0.05), CD8⁺IFN-gamma⁺IL-4- (p<0.05 and p<0.01, respectively) and CD4⁺TNF-alpha⁺ cells (p<0.05) compared with early RA. CD3⁺CD4⁺ cells were higher in PMR than in RS3PE (p<0.01), but there were no significant differences in any other phenotypes between these disorders. A decrease in activated cytotoxic/suppressor T cells and increases in circulating Th1 and Tc1 cells may be common characteristics of PMR and RS3PE in comparison with early RA. Both disorders are clearly different from early RA, and probably belong to the same disease entity with regard to phenotypes of peripheral blood lymphocytes.

Early stages of transition in viscosity-stratified channel flow

NASA Astrophysics Data System (ADS)

Govindarajan, Rama; Jose, Sharath; Brandt, Luca

2013-11-01

In parallel shear flows, it is well known that transition to turbulence usually occurs through a subcritical process. In this work we consider a flow through a channel across which there is a linear temperature variation. The temperature gradient leads to a viscosity variation across the channel. A large body of work has been done in the linear regime for this problem, and it has been seen that viscosity stratification can lead to considerable changes in stability and transient growth characteristics. Moreover contradictory effects of introducing a non uniform viscosity in the system have been reported. We conduct a linear stability analysis and direct numerical simulations (DNS) for this system. We show that the optimal initial structures in the viscosity-stratified case, unlike in unstratified flow, do not span the width of the channel, but are focussed near one wall. The nonlinear consequences of the localisation of the structures will be discussed.

Relationship between early administration of abciximab and TIMI flow in STEMI patients undergoing primary angioplasty: findings from a large regional STEMI network.

PubMed

Izzo, Antonio; Rosiello, Renato; Lucchini, Giuseppe; Tomasi, Luca; Mantovani, Paola; Lettieri, Corrado; Baccaglioni, Nicola; Romano, Michele; Buffoli, Francesca; Izzo, Beatrice; Zanini, Roberto

2017-06-01

The aim of this study is to assess whether in S-T Elevation Myocardial Infarction (STEMI) a relationship between early administration of abciximab and Thrombolysis In Myocardial Infarction (TIMI) flow before and after primary percutaneous coronary intervention (PCI) in 960 consecutive patients exists. From 1 February 2001 onward, in the Province of Mantua it has been operating a 'Cardiology Network for the Acute Infarction Care' having its Hub in the Central Coronary ICU/Cath Lab of Mantua Hospital and being its Spokes centers represented by the emergency rooms and Central Coronary ICUs of the four territorial hospitals. T1 (time from symptoms onset to first medical contact) and T2 (time from first medical contact to angioplasty) are shorter for patients rescued by first aid units rather than for those presented in emergency rooms as well as Ta (time from symptoms onset to abciximab administration). Furthermore, the patients that received abciximab before hospital arrival had less frequently a coronary occlusion [odds ratio = 0.74, 95% confidence interval (0.57-0.96), P = 0.013]. The patients with T1 less than 4 h are 753/960 (78.4%). For this type of patients, there was a significant Ta difference between the pre-PCI TIMI-flow classes (F = 4.467, df = 3, P = 0.04). Planned contrasts revealed that mean time of TIMI flow 0 (M = 104.2) is statistically different from mean time of TIMI flow 3 (M = 85.7), P = 0.013. Our results suggest that the use of abciximab, free from pharmacokinetic limits of oral P2Y12 inhibitors, should be considered in STEMI patients with early presentation before primary PCI.

Incidence and risk factors of early arterial blood flow stasis during first radioembolization of primary and secondary liver malignancy using resin microspheres: an initial single-center analysis.

PubMed

Pieper, Claus Christian; Willinek, Winfried A; Thomas, Daniel; Ahmadzadehfar, Hojjat; Essler, Markus; Nadal, Jennifer; Wilhelm, Kai E; Schild, Hans Heinz; Meyer, Carsten

2016-08-01

To retrospectively determine incidence of early arterial blood flow stasis and its influencing factors during resin-based radioembolization (RE) of liver tumours. Data of patients undergoing resin-based RE from 06/2006-12/2013 were reviewed. Second RE procedures of the same liver lobe were excluded. 90-yttrium dose was calculated according to the body surface area method. Data were categorized according to RE without full dose application because of early stasis and with full dose application. Clinical/procedural characteristics were recorded. Logistic regression was performed to identify associations between clinical/procedural characteristics and early stasis. 362 patients [220 male; mean age 62 years (range 26-90)] underwent 416 RE sessions with early stasis occurring in 103 REs (24.8 %). Highest incidence and degree of stasis were observed in breast cancer metastases [42.6 % (20/47); 55.8 % of mean intended dose administered]. Independent risk factors were: metastasized breast cancer (odds ratio [OR] 2.18, p = 0.02), liver tumour-burden <25 % and 25-50 % (ORs 5.33, 15.64; p < 0.0001), tumour hypovascularity (OR 2.70, p = 0.04), previous bevacizumab therapy (OR 2.79, p = 0.0009) and concurrent chemotherapy (OR 8.69, p < 0.0001). Early stasis was observed in 24.8 % of resin-based REs. In the presence of the identified risk factors, extra care should be taken during microsphere administration. • Early arterial blood flow stasis is a known problem of resin-based RE. • The study showed that early stasis occurs in 25 % of REs. • Several clinical and procedural factors are associated with early stasis. • In patients at risk extra care should be taken during RE.

An Integrated Phosphoproteomics Work Flow Reveals Extensive Network Regulation in Early Lysophosphatidic Acid Signaling*

PubMed Central

Schreiber, Thiemo B.; Mäusbacher, Nina; Kéri, György; Cox, Jürgen; Daub, Henrik

2010-01-01

Lysophosphatidic acid (LPA) induces a variety of cellular signaling pathways through the activation of its cognate G protein-coupled receptors. To investigate early LPA responses and assess the contribution of epidermal growth factor (EGF) receptor transactivation in LPA signaling, we performed phosphoproteomics analyses of both total cell lysate and protein kinase-enriched fractions as complementary strategies to monitor phosphorylation changes in A498 kidney carcinoma cells. Our integrated work flow enabled the identification and quantification of more than 5,300 phosphorylation sites of which 224 were consistently regulated by LPA. In addition to induced phosphorylation events, we also obtained evidence for early dephosphorylation reactions due to rapid phosphatase regulation upon LPA treatment. Phosphorylation changes induced by direct heparin-binding EGF-like growth factor-mediated EGF receptor activation were typically weaker and only detected on a subset of LPA-regulated sites, indicating signal integration among EGF receptor transactivation and other LPA-triggered pathways. Our results reveal rapid phosphoregulation of many proteins not yet implicated in G protein-coupled receptor signaling and point to various additional mechanisms by which LPA might regulate cell survival and migration as well as gene transcription on the molecular level. Moreover, our phosphoproteomics analysis of both total lysate and kinase-enriched fractions provided highly complementary parts of the LPA-regulated signaling network and thus represents a useful and generic strategy toward comprehensive signaling studies on a system-wide level. PMID:20071362

Monitoring blood flow responses during topical ALA-PDT

PubMed Central

Becker, Theresa L.; Paquette, Anne D.; Keymel, Kenneth R.; Henderson, Barbara W.; Sunar, Ulas

2011-01-01

Photodynamic therapy (PDT) using topical 5-aminolevulinic acid (ALA) is currently used as a clinical treatment for nonmelanoma skin cancers. In order to optimize PDT treatment, vascular disruption early in treatment must be identified and prevented. We present blood flow responses to topical ALA-PDT in a preclinical model and basal cell carcinoma patients assessed by diffuse correlation spectroscopy (DCS). Our results show that ALA-PDT induced early blood flow changes and these changes were irradiance dependent. It is clear that there exists considerable variation in the blood flow responses in patients from lesion to lesion. Monitoring blood flow parameter may be useful for assessing ALA-PDT response and planning. PMID:21326642

Effect of reading on blood flow changes in the posterior cerebral artery in early blind and sighted people--A transcranial Doppler study.

PubMed

Viski, Sandor; Orgovan, David; Szabo, Katalin; Rosengarten, Bernhard; Csiba, Laszlo; Olah, Laszlo

2016-04-15

Neuroimaging studies proved that Braille reading resulted in visual cortex activation in blind people, however, very few data are available about the measure of flow increase in these subjects. Therefore, we investigated the flow response in the posterior cerebral artery (PCA) of eleven early blind and ten sighted subjects induced by reading Braille and print, respectively. Two experimental protocols were used in both groups: PCA flow velocity during reading was compared to the resting phase and "NLC" phase (volunteers "read" non-lexical characters; e.g. .,-.:,-.:...,). The use of these experimental protocols allowed to investigate separately the effect of "light stimulus+print reading" versus "print reading alone" in sighted, and "hand/finger movement+Braille reading" versus "Braille reading alone" in blind subjects. The flow response in the PCA evoked by "Braille reading alone" in blind (10.5±4.5%) and "print reading alone" in sighted subjects (8.1±3.5%) was similar. The flow increase induced by "hand/finger movement+Braille reading" and by "Braille reading alone" did not differ in blind people, however, "light stimulus+print reading" in sighted subjects caused higher PCA flow increase (25.9±6.9%) than "print reading alone" (8.1±3.5%). The similar PCA flow response induced by Braille and print reading alone suggested a similar degree of occipital cortex activation in blind and sighted subjects. In sighted people, the 3-times higher flow velocity increase induced by "light stimulus+print reading" compared with "print reading alone" indicated that 2/3 of PCA flow increase during reading was due to the light stimulus and only 1/3 of flow response was caused by reading alone. Copyright © 2016 Elsevier B.V. All rights reserved.

End-of-life flows of multiple cycle consumer products.

PubMed

Tsiliyannis, C A

2011-11-01

Explicit expressions for the end-of-life flows (EOL) of single and multiple cycle products (MCPs) are presented, including deterministic and stochastic EOL exit. The expressions are given in terms of the physical parameters (maximum lifetime, T, annual cycling frequency, f, number of cycles, N, and early discard or usage loss). EOL flows are also obtained for hi-tech products, which are rapidly renewed and thus may not attain steady state (e.g., electronic products, passenger cars). A ten-step recursive procedure for obtaining the dynamic EOL flow evolution is proposed. Applications of the EOL expressions and the ten-step procedure are given for electric household appliances, industrial machinery, tyres, vehicles and buildings, both for deterministic and stochastic EOL exit, (normal, Weibull and uniform exit distributions). The effect of the physical parameters and the stochastic characteristics on the EOL flow is investigated in the examples: it is shown that the EOL flow profile is determined primarily by the early discard dynamics; it also depends strongly on longevity and cycling frequency: higher lifetime or early discard/loss imply lower dynamic and steady state EOL flows. The stochastic exit shapes the overall EOL dynamic profile: Under symmetric EOL exit distribution, as the variance of the distribution increases (uniform to normal to deterministic) the initial EOL flow rise becomes steeper but the steady state or maximum EOL flow level is lower. The steepest EOL flow profile, featuring the highest steady state or maximum level, as well, corresponds to skew, earlier shifted EOL exit (e.g., Weibull). Since the EOL flow of returned products consists the sink of the reuse/remanufacturing cycle (sink to recycle) the results may be used in closed loop product lifecycle management operations for scheduling and sizing reverse manufacturing and for planning recycle logistics. Decoupling and quantification of both the full age EOL and of the early discard flows is

Aspherical Supernovae: Effects on Early Light Curves

NASA Astrophysics Data System (ADS)

Afsariardchi, Niloufar; Matzner, Christopher D.

2018-04-01

Early light from core-collapse supernovae, now detectable in high-cadence surveys, holds clues to a star and its environment just before it explodes. However, effects that alter the early light have not been fully explored. We highlight the possibility of nonradial flows at the time of shock breakout. These develop in sufficiently nonspherical explosions if the progenitor is not too diffuse. When they do develop, nonradial flows limit ejecta speeds and cause ejecta–ejecta collisions. We explore these phenomena and their observational implications using global, axisymmetric, nonrelativistic FLASH simulations of simplified polytropic progenitors, which we scale to representative stars. We develop a method to track photon production within the ejecta, enabling us to estimate band-dependent light curves from adiabatic simulations. Immediate breakout emission becomes hidden as an oblique flow develops. Nonspherical effects lead the shock-heated ejecta to release a more constant luminosity at a higher, evolving color temperature at early times, effectively mixing breakout light with the early light curve. Collisions between nonradial ejecta thermalize a small fraction of the explosion energy; we will address emission from these collisions in a subsequent paper.

Creating a Context for Flow: The Importance of Personal Insight and Experience

ERIC Educational Resources Information Center

Rathunde, Kevin

2015-01-01

Kevin Rathunde reflects on his early studies of flow in Montessori adolescents and surmises that adults need to experience their own flow in order to guide young people to peak levels. He recounts his early music experiences as having "peaked" and that he needed to come back to his flow of the past to fully enter into his work with flow…

Effects of fluctuating flows and a controlled flood on incubation success and early survival rates and growth of age-0 rainbow trout in a large regulated river

USGS Publications Warehouse

Korman, Josh; Kaplinski, Matthew; Melis, Theodore S.

2011-01-01

Hourly fluctuations in flow from Glen Canyon Dam were increased in an attempt to limit the population of nonnative rainbow trout Oncorhynchus mykiss in the Colorado River, Arizona, due to concerns about negative effects of nonnative trout on endangered native fishes. Controlled floods have also been conducted to enhance native fish habitat. We estimated that rainbow trout incubation mortality rates resulting from greater fluctuations in flow were 23-49% (2003 and 2004) compared with 5-11% under normal flow fluctuations (2006-2010). Effects of this mortality were apparent in redd excavations but were not seen in hatch date distributions or in the abundance of the age-0 population. Multiple lines of evidence indicated that a controlled flood in March 2008, which was intended to enhance native fish habitat, resulted in a large increase in early survival rates of age-0 rainbow trout. Age-0 abundance in July 2008 was over fourfold higher than expected given the number of viable eggs that produced these fish. A hatch date analysis indicated that early survival rates were much higher for cohorts that hatched about 1 month after the controlled flood (~April 15) relative to those that hatched before this date. The cohorts that were fertilized after the flood were not exposed to high flows and emerged into better-quality habitat with elevated food availability. Interannual differences in age-0 rainbow trout growth based on otolith microstructure supported this hypothesis. It is likely that strong compensation in survival rates shortly after emergence mitigated the impact of incubation losses caused by increases in flow fluctuations. Control of nonnative fish populations will be most effective when additional mortality is applied to older life stages after the majority of density-dependent mortality has occurred. Our study highlights the need to rigorously assess instream flow decisions through the evaluation of population-level responses.

Interrupted commissural band annuloplasty prevents mitral stenosis.

PubMed

Sawazaki, Masaru; Tomari, Shiro; Zaikokuji, Kenta; Imaeda, Yusuke

2016-09-01

Mitral annuloplasty is an important component of the treatment of degenerative mitral valve disease. However, postoperative echocardiography reveals elevated mitral gradients in some patients. We developed a technique that we termed interrupted commissural band annuloplasty (iCBA), which does not shorten either the anterior or posterior annulus and is not associated with the development of a mitral gradient. We compared the echocardiographic characteristics of patients treated using this method versus Cosgrove ring (COS) placement, both at rest and during exercise. ICBA features placement of three sutures in the commissures using two bands and shortens the commissural annular length by 60 %. We used this method to treat 63 patients and placed Cosgrove bands in 58. Of all patients, 48 who underwent iCBA and 34 with COSs passed the exercise echocardiographic test. The maximal transmitral pressures at rest in the iCBA and Cosgrove groups were 8.04 ± 0.74 and 11.30 ± 0.88 mmHg (P = 0.0029), respectively, and the mean transmitral pressures at rest were 2.46 ± 0.74 and 3.61 ± 0.32 mmHg (P = 0.0037), respectively. The maximal transmitral pressures during exercise were 11.79 ± 0.97 and 18.37 ± 1.16 mmHg (P < 0.0001), and the mean transmitral pressures during exercise were 4.95 ± 0.45 and 7.76 ± 0.53 mmHg (P < 0.0001). ICBA prevents postoperative mitral stenosis both at rest and importantly during exercise.

Pattern formation and three-dimensional instability in rotating flows

NASA Astrophysics Data System (ADS)

Christensen, Erik A.; Aubry, Nadine; Sorensen, Jens N.

1997-03-01

A fluid flow enclosed in a cylindrical container where fluid motion is created by the rotation of one end wall as a centrifugal fan is studied. Direct numerical simulations and spatio-temporal analysis have been performed in the early transition scenario, which includes a steady-unsteady transition and a breakdown of axisymmetric to three-dimensional flow behavior. In the early unsteady regime of the flow, the central vortex undergoes a vertical beating motion, accompanied by axisymmetric spikes formation on the edge of the breakdown bubble. As traveling waves, the spikes move along the central vortex core toward the rotating end-wall. As the Reynolds number is increased further, the flow undergoes a three-dimensional instability. The influence of the latter on the previous patterns is studied.

Overview of Laminar Flow Control

NASA Technical Reports Server (NTRS)

Joslin, Ronald D.

1998-01-01

The history of Laminar Flow Control (LFC) from the 1930s through the 1990s is reviewed and the current status of the technology is assessed. Early studies related to the natural laminar boundary-layer flow physics, manufacturing tolerances for laminar flow, and insect-contamination avoidance are discussed. Although most of this publication is about slot-, porous-, and perforated-suction LFC concept studies in wind tunnel and flight experiments, some mention is made of thermal LFC. Theoretical and computational tools to describe the LFC aerodynamics are included for completeness.

Tissue Doppler Imaging in Coronary Artery Diseases and Heart Failure

PubMed Central

Correale, Michele; Totaro, Antonio; Ieva, Riccardo; Ferraretti, Armando; Musaico, Francesco; Biase, Matteo Di

2012-01-01

Recent studies have explored the prognostic role of TDI-derived parameters in major cardiac diseases, such as coronary artery disease (CAD) and heart failure (HF). In these conditions, myocardial mitral annular systolic (S’) and early diastolic (E’) velocities have been shown to predict mortality or cardiovascular events. In heart failure non invasive assessment of LV diastolic pressure by transmitral to mitral annular early diastolic velocity ratio (E/E’) is a strong prognosticator, especially when E/E’ is > or =15. Moreover, other parameters derived by TDI, as cardiac time intervals and Myocardial Performance Index, might play a role in the prognostic stratification in CAD and HF. Recently, a three-dimensional (3-D) TDI imaging modality, triplane TDI, has become available, and this allows calculation of 3-Dvolumes and LV ejection fraction. We present a brief update of TDI. PMID:22845815

Results of Early High-Flow Bypass and Trapping for Ruptured Blood Blister-Like Aneurysms of the Internal Carotid Artery.

PubMed

Kikkawa, Yuichiro; Ikeda, Toshiki; Takeda, Ririko; Nakajima, Hiroyuki; Ogura, Takeshi; Ooigawa, Hidetoshi; Kurita, Hiroki

2017-09-01

The aim of this study is to clarify the efficacy and safety of early surgery using trapping of the affected internal carotid artery (ICA) and high-flow bypass between the second portion of the middle cerebral artery and cervical external carotid artery with radial artery graft for ruptured blood blister-like aneurysms (BBAs) arising from the anterior wall of the ICA. Medical charts of 16 consecutive patients (7 men and 9 women; mean, 59 years) with subarachnoid hemorrhage (World Federation of Neurosurgical Societies grade I, n = 2; grade II, n = 5; grade III, n = 2; grade IV, n = 4; grade V, n = 3) caused by ruptured BBA surgically treated between July 2010 and October 2015 were retrospectively reviewed. Eleven patients underwent acute surgery within 24 hours after the onset, whereas surgery was performed between 3 and 17 days after the onset because of referral delay or associated vasospasm in 5 patients. All patients underwent the same surgical procedure. Elimination of the BBA and patency of the bypass were achieved in all patients. Postoperatively, 2 patients showed small infarction in the Heubner artery area, and 2 others suffered symptomatic vasospasm, but no patient suffered infarction in the posterior communicating/anterior choroidal artery territories. Identically, no patient showed ischemic optic neuropathy. At the last follow-up (mean, 36 months), favorable clinical outcome (good recovery or mild disability in Glasgow Outcome Scale) was achieved in 14 (88%) of the patients without rebleeding or refilling of the aneurysms. Early surgical repair of BBAs by trapping of the affected ICA with high-flow bypass is safe and effective treatment with satisfactory midterm outcome. Copyright © 2017 Elsevier Inc. All rights reserved.

How Does Subclinical Hyperthyroidism Affect Right Heart Function and Mechanics?

PubMed

Tadic, Marijana; Celic, Vera; Cuspidi, Cesare; Ilic, Sanja; Zivanovic, Vladimir; Marjanovic, Tamara

2016-02-01

Right heart function and mechanics have not been investigated in patients with subclinical hyperthyroidism. Our aim was to investigate right ventricular (RV) and right atrial (RA) function and deformation as evaluated by 3-dimensional echocardiography (3DE) and speckle-tracking 2-dimensional echocardiography (2DE) in these individuals. We included 39 untreated women with endogenous subclinical hyperthyroidism and 39 healthy women matched by age. All participants underwent laboratory analyses that included thyroid hormone levels and comprehensive 2DE and 3DE examinations. Three-dimensional echocardiographic RV volumes were significantly elevated in the patients with subclinical hyperthyroidism (P < .05), whereas the 3DE RV ejection fraction was reduced in this group, but with borderline significance. Two-dimensional echocardiographic longitudinal RV and RA strain were significantly reduced in the patients with subclinical hyperthyroidism. Two-dimensional echocardiographic RV systolic and early diastolic strain rates were reduced, whereas late diastolic strain rates were increased in the patients with subclinical hyperthyroidism. The same changes were detected in RA mechanics among the patients with subclinical hyperthyroidism. The thyrotropin (TSH) level correlated with the left ventricular mass index, transmitral early diastolic peak flow velocity (E)/late diastolic flow velocity (A) ratio, tricuspid E/A ratio, 2DE RV global strain, 2DE RA, strain, and 3DE RV end-diastolic volume. A multivariate regression analysis showed that the mitral E/A ratio, 2DE RV global strain, and 3DE RV end-diastolic volume were independently associated with the TSH level. Right ventricular and RA function as evaluated by 3DE and speckle-tracking 2DE is significantly impaired in patients with subclinical hyperthyroidism. The TSH level correlated with parameters for RV function and mechanics in the whole study population. © 2016 by the American Institute of Ultrasound in Medicine.

Dynamics of DNA replication during premeiosis and early meiosis in wheat.

PubMed

Rey, María-Dolores; Prieto, Pilar

2014-01-01

Meiosis is a specialised cell division that involves chromosome replication, two rounds of chromosome segregation and results in the formation of the gametes. Meiotic DNA replication generally precedes chromosome pairing, recombination and synapsis in sexually developing eukaryotes. In this work, replication has been studied during premeiosis and early meiosis in wheat using flow cytometry, which has allowed the quantification of the amount of DNA in wheat anther in each phase of the cell cycle during premeiosis and each stage of early meiosis. Flow cytometry has been revealed as a suitable and user-friendly tool to detect and quantify DNA replication during early meiosis in wheat. Chromosome replication was detected in wheat during premeiosis and early meiosis until the stage of pachytene, when chromosomes are associated in pairs to further recombine and correctly segregate in the gametes. In addition, the effect of the Ph1 locus, which controls chromosome pairing and affects replication in wheat, was also studied by flow cytometry. Here we showed that the Ph1 locus plays an important role on the length of meiotic DNA replication in wheat, particularly affecting the rate of replication during early meiosis in wheat.

Dynamics of DNA Replication during Premeiosis and Early Meiosis in Wheat

PubMed Central

Rey, María-Dolores; Prieto, Pilar

2014-01-01

Meiosis is a specialised cell division that involves chromosome replication, two rounds of chromosome segregation and results in the formation of the gametes. Meiotic DNA replication generally precedes chromosome pairing, recombination and synapsis in sexually developing eukaryotes. In this work, replication has been studied during premeiosis and early meiosis in wheat using flow cytometry, which has allowed the quantification of the amount of DNA in wheat anther in each phase of the cell cycle during premeiosis and each stage of early meiosis. Flow cytometry has been revealed as a suitable and user-friendly tool to detect and quantify DNA replication during early meiosis in wheat. Chromosome replication was detected in wheat during premeiosis and early meiosis until the stage of pachytene, when chromosomes are associated in pairs to further recombine and correctly segregate in the gametes. In addition, the effect of the Ph1 locus, which controls chromosome pairing and affects replication in wheat, was also studied by flow cytometry. Here we showed that the Ph1 locus plays an important role on the length of meiotic DNA replication in wheat, particularly affecting the rate of replication during early meiosis in wheat. PMID:25275307

Doppler echocardiographic assessment of left ventricular diastolic function in 74 boxer dogs with aortic stenosis.

PubMed

Schober, Karsten E; Fuentes, Virginia Luis

2002-05-01

To evaluate left ventricular (LV) diastolic function in boxer dogs with aortic stenosis (AS). LV relaxation, elastic recoil, filling and stiffness have been found to be abnormal in people with AS and were related to disease severity, clinical signs and prognosis. 2-D, M-mode and Doppler echocardiography was done in 74 boxers with AS (55 with mild AS, 7 with moderate AS and 12 with severe AS) and compared with reference values from 66 normal boxers. Measurements included isovolumic relaxation time (IVRT), peak early (E) and late (A) transmitral filling velocities, mitral E wave deceleration time, peak systolic, and early and late (AR) diastolic pulmonary wenous flow velocities and related variables. In addition, left atrial (LA) function, LV dimensions and hypertrophy and LV systolic performance were assessed. Eight dogs (15%) with mild AS had abnormal LV diastolic function, compared with 16 dogs (84%) with moderate or severe AS. Two dogs (3%) had also systolic abnormalities. The flow pattern of delayed relaxation, pseudonormal mitral inflow and restrictive flow were found in 10, 11 and 3 dogs, respectively. IVRT and E:A were heterogeneous in dogs with moderate or severe AS, being either high, normal, or low. Peak AR velocity was significantly higher (p

Early warning of footpad dermatitis and hockburn in broiler chicken flocks using optical flow, bodyweight and water consumption.

PubMed

Dawkins, M S; Roberts, S J; Cain, R J; Nickson, T; Donnelly, C A

2017-05-20

Footpad dermatitis and hockburn are serious welfare and economic issues for the production of broiler (meat) chickens. The authors here describe the use of an inexpensive camera system that monitors the movements of broiler flocks throughout their lives and suggest that it is possible to predict, even in young birds, the cross-sectional prevalence at slaughter of footpad dermatitis and hockburn before external signs are visible. The skew and kurtosis calculated from the authors' camera-based optical flow system had considerably more power to predict these outcomes in the 50 flocks reported here than water consumption, bodyweight or mortality and therefore have the potential to inform improved flock management through giving farmers early warning of welfare issues. Further trials are underway to establish the generality of the results. British Veterinary Association.

Analysis of Mass Profiles and Cooling Flows of Bright, Early-Type Galaxies AO2, AO3 and Surface Brightness Profiles and Energetics of Intracluster Gas in Cool Galaxy Clusters AO3

NASA Technical Reports Server (NTRS)

White, Raymond E., III

1998-01-01

This final report uses ROSAT observations to analyze two different studies. These studies are: Analysis of Mass Profiles and Cooling Flows of Bright, Early-Type Galaxies; and Surface Brightness Profiles and Energetics of Intracluster Gas in Cool Galaxy Clusters.

Early formation of preferential flow in a homogeneous snowpack observed by micro-CT

NASA Astrophysics Data System (ADS)

Avanzi, Francesco; Petrucci, Giacomo; Matzl, Margret; Schneebeli, Martin; De Michele, Carlo

2017-05-01

We performed X-ray microtomographic observations of wet-snow metamorphism during controlled continuous melting and melt-freeze events in the laboratory. Three blocks of snow were sieved into boxes and subjected to cyclic, superficial heating or heating-cooling to reproduce vertical water infiltration patterns in snow similarly to natural conditions. Periodically, samples were taken at different heights and scanned. Results suggest that wet-snow metamorphism dynamics are highly heterogeneous even in an initially homogeneous snowpack. Consistent with previous work, we observed an increase with time in the thickness of the ice structure, which is a measure of grain size. However, this was coupled with large temporal scatter between consecutive measurements of the specific surface area and of the statistical moments of grain thickness distributions. Because of marked differences in the right tail, grain thickness distributions did not show shape invariance with time, contrary to previous analyses. In our experiments, wet-snow metamorphism showed two strikingly different patterns: homogeneous coarsening superimposed by faster heterogeneous coarsening in areas that were affected by preferential percolation of water. Liquid water movement in snow and fast structural evolution may be thus intrinsically coupled by early formation of preferential flow at local scale. These observations suggest that further experiments are highly needed to fully understand wet-snow metamorphism and infiltration patterns in a natural snowpack.

Computational methods for unsteady transonic flows

NASA Technical Reports Server (NTRS)

Edwards, John W.; Thomas, J. L.

1987-01-01

Computational methods for unsteady transonic flows are surveyed with emphasis on prediction. Computational difficulty is discussed with respect to type of unsteady flow; attached, mixed (attached/separated) and separated. Significant early computations of shock motions, aileron buzz and periodic oscillations are discussed. The maturation of computational methods towards the capability of treating complete vehicles with reasonable computational resources is noted and a survey of recent comparisons with experimental results is compiled. The importance of mixed attached and separated flow modeling for aeroelastic analysis is discussed, and recent calculations of periodic aerodynamic oscillations for an 18 percent thick circular arc airfoil are given.

Effects of High-Flow Experiments from Glen Canyon Dam on Abundance, Growth, and Survival Rates of Early Life Stages of Rainbow Trout in the Lees Ferry Reach of the Colorado River

USGS Publications Warehouse

Korman, Josh; Kaplinski, Matthew; Melis, Theodore S.

2010-01-01

High-flow experiments (HFEs) from Glen Canyon Dam are primarily intended to conserve fine sediment and improve habitat conditions for native fish in the Colorado River as it flows through Grand Canyon National Park, Arizona. These experimental flows also have the potential to affect the rainbow trout (Oncorhynchus mykiss) population in the Lees Ferry tailwater reach immediately below the dam, which supports a highly valued recreational fishery and likely influences the abundance of rainbow trout in Grand Canyon. Understanding how flow regimes affect the survival and growth of juvenile rainbow trout is critical to interpreting trends in adult abundance. This study reports on the effects of HFEs in 2004 and 2008 on early life stages of rainbow trout in the Lees Ferry reach on the basis of monthly sampling of redds (egg nests) and the abundance of the age-0 trout (fertilization to about 1 to 2 months from emergence) and their growth during a 7-year period between 2003 and 2009. Multiple lines of evidence indicate that the March 2008 HFE resulted in a large increase in early survival rates of age-0 trout because of an improvement in habitat conditions. A stock-recruitment analysis demonstrated that age-0 abundance in July 2008 was more than fourfold higher than expected, given the number of viable eggs that produced these fish. A hatch-date analysis showed that early survival rates were much higher for cohorts that hatched about 1 month after the 2008 HFE (about April 15, 2008) relative to those fish that hatched before this date. These cohorts, fertilized after the 2008 HFE, would have emerged into a benthic invertebrate community that had recovered, and was possibly enhanced by, the HFE. Interannual differences in growth of age-0 trout, determined on the basis of otolith microstructure, support this hypothesis. Growth rates in the summer and fall of 2008 (0.44 mm/day) were virtually the same as in 2006 (0.46 mm/day), the highest recorded during 6 years, even though

Impact cratering calculations. Part 1: Early time results

NASA Technical Reports Server (NTRS)

Thomsen, J. M.; Sauer, F. N.; Austin, M. G.; Ruhl, S. F.; Shultz, P. H.; Orphal, D. L.

1979-01-01

Early time two dimensional finite difference calculations of laboratory scale hypervelocity impact of 0.3 g spherical 2024 aluminum projectiles into homogeneous plasticene clay targets were performed. Analysis of resulting material motions showed that energy and momentum were coupled quickly from the aluminum projectile to the target material. In the process of coupling, some of the plasticene clay target was vaporized while the projectile become severely deformed. The velocity flow field developed within the target was shown to have features similar to those found in calculations of near surface explosion cratering. Specific application of Maxwell's analytic Z-Model showed that this model can be used to describe the early time flow fields resulting from the impact cratering calculations as well, provided the flow field centers are located beneath the target surface and most of the projectile momentum is dissipated before the model is applied.

A Unified View of Global Instabilities of Compressible Flow Over Open Cavities

DTIC Science & Technology

2005-06-30

the early work of Rossiter [3], have treated the shear-layer emanating from the upstream comer of the cavity in isolation ( using parallel flow... using a domain-decomposition method. The code has optional equation sets to solve either (i) nonlinear Navier-Stokes, (ii) Navier-Stokes equations...early experments of Maull and East [15]. They used oil flow visualization of surface streamlines on the cavity bottom to show the existence, under certain

The evolution of cooling flows. I - Self-similar cluster flows. [of gas in intergalactic medium

NASA Technical Reports Server (NTRS)

Chevalier, Roger A.

1987-01-01

The evolution of a cooling flow from an initial state of hydrostatic equilibrium in a cluster of galaxies is investigated. After gas mass and energy are injected into the cluster at an early phase, the gas approaches hydrostatic equilibrium over most of the cluster and cooling becomes important in the dense central regions. As time passes, cooling strongly affects an increasing amount of gas. The effects of mass removal from the flow, the inclusion of magnetic or cosmic-ray pressure, and heat conduction are considered individually.

Spectral features of solar plasma flows

NASA Astrophysics Data System (ADS)

Barkhatov, N. A.; Revunov, S. E.

2014-11-01

Research to the identification of plasma flows in the Solar wind by spectral characteristics of solar plasma flows in the range of magnetohydrodynamics is devoted. To do this, the wavelet skeleton pattern of Solar wind parameters recorded on Earth orbit by patrol spacecraft and then executed their neural network classification differentiated by bandwidths is carry out. This analysis of spectral features of Solar plasma flows in the form of magnetic clouds (MC), corotating interaction regions (CIR), shock waves (Shocks) and highspeed streams from coronal holes (HSS) was made. The proposed data processing and the original correlation-spectral method for processing information about the Solar wind flows for further classification as online monitoring of near space can be used. This approach will allow on early stages in the Solar wind flow detect geoeffective structure to predict global geomagnetic disturbances.

Project Rulison gas flow analysis

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

Montan, D.N.

1971-01-01

An analysis of the well performance was attempted by fitting a simple model of the chimney, gas sands, and explosively created fracturing to the 2 experimentally measured variables, flow rate, and chimney pressure. The gas-flow calculations for various trial models were done by a finite difference solution to the nonlinear partial differential equation for radial Darcy flow. The TRUMP computer program was used to perform the numerical calculations. In principle, either the flow rate or the chimney pressure could be used as the independent variable in the calculations. In the present case, the flow rate was used as the independentmore » variable, since chimney pressure measurements were not made until after the second flow period in early Nov. 1970. Furthermore, the formation pressure was not accurately known and, hence, was considered a variable parameter in the modeling process. The chimney pressure was assumed equal to the formation pressure at the beginning of the flow testing. The model consisted of a central zone, representing the chimney, surrounded by a number of concentric zones, representing the formation. The effect of explosive fracturing was simulated by increasing the permeability in the zones near the central zone.« less

Graft flow assessment using a transit time flow meter in fractional flow reserve-guided coronary artery bypass surgery.

PubMed

Honda, Kentaro; Okamura, Yoshitaka; Nishimura, Yoshiharu; Uchita, Shunji; Yuzaki, Mitsuru; Kaneko, Masahiro; Yamamoto, Nobuko; Kubo, Takashi; Akasaka, Takashi

2015-06-01

To evaluate the relationship between preoperative severity of coronary stenosis occurring with fractional flow reserve (FFR), and the intraoperative bypass graft flow pattern. In all, 72 patients were enrolled in this retrospective study. The FFR value of the left anterior descending artery was evaluated, and data on "in situ" bypass grafting from the internal thoracic artery to the left anterior descending artery were assessed. Patients were divided into 3 groups according to preoperative FFR values (Group S: FFR < 0.70; group M: 0.70 ≤ FFR < 0.75; and group N: FFR ≥ 0.75). In groups S, M, and N, respectively, mean graft flow was 24.7 ± 10.6 mL/minute, 19.2 ± 14.0 mL/minute, and 16.0 ± 9.7 mL mL/minute; pulsatility index was 2.35 ± 0.6, 3.02 ± 1.1, and 5.51 ± 8.20; and number of patients with systolic reverse flow was 3 (6.8%), 5 (35.7%), and 4 (28.6%). Significant differences were observed in graft flow (P = .009), pulsatility index (P = .038), and proportion of systolic reverse flow (P = .023) among the 3 groups. In all patients, graft patency was confirmed with intraoperative fluorescence imaging; postoperative graft patency was confirmed with multislice computed tomography or coronary angiography in 69 patients (follow-up interval: 213 days). Early graft failure occurred in 1 patient. As coronary stenosis severity increased, graft flow increased, pulsatility index decreased, and proportion of patients with systolic reverse flow increased. In mild coronary artery stenosis, the chance of flow competition between the native coronary artery and the bypass graft increased. Copyright © 2015 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.

Hemodynamic flow visualization of early embryonic great vessels using μPIV.

PubMed

Goktas, Selda; Chen, Chia-Yuan; Kowalski, William J; Pekkan, Kerem

2015-01-01

Microparticle image velocimetry (μPIV) is an evolving quantitative methodology to closely and accurately monitor the cardiac flow dynamics and mechanotransduction during vascular morphogenesis. While PIV technique has a long history, contemporary developments in advanced microscopy have significantly expanded its power. This chapter includes three new methods for μPIV acquisition in selected embryonic structures achieved through advanced optical imaging: (1) high-speed confocal scanning of transgenic zebrafish embryos, where the transgenic erythrocytes act as the tracing particles; (2) microinjection of artificial seeding particles in chick embryos visualized with stereomicroscopy; and (3) real-time, time-resolved optical coherence tomography acquisition of vitelline vessel flow profiles in chick embryos, tracking the erythrocytes.

Talent Flow from Undergraduate to Graduate School: 1982-1993.

ERIC Educational Resources Information Center

Grandy, Jerilee

This report describes the early development, recent revision, and some uses of a special Graduate Record Examinations (GRE) database for studying talent flow between undergraduate and graduate school. It discusses the following: (1) development and expansion of a talent flow database containing all variables from the GRE General Test files on all…

Ancient gene flow from early modern humans into Eastern Neanderthals.

PubMed

Kuhlwilm, Martin; Gronau, Ilan; Hubisz, Melissa J; de Filippo, Cesare; Prado-Martinez, Javier; Kircher, Martin; Fu, Qiaomei; Burbano, Hernán A; Lalueza-Fox, Carles; de la Rasilla, Marco; Rosas, Antonio; Rudan, Pavao; Brajkovic, Dejana; Kucan, Željko; Gušic, Ivan; Marques-Bonet, Tomas; Andrés, Aida M; Viola, Bence; Pääbo, Svante; Meyer, Matthias; Siepel, Adam; Castellano, Sergi

2016-02-25

It has been shown that Neanderthals contributed genetically to modern humans outside Africa 47,000-65,000 years ago. Here we analyse the genomes of a Neanderthal and a Denisovan from the Altai Mountains in Siberia together with the sequences of chromosome 21 of two Neanderthals from Spain and Croatia. We find that a population that diverged early from other modern humans in Africa contributed genetically to the ancestors of Neanderthals from the Altai Mountains roughly 100,000 years ago. By contrast, we do not detect such a genetic contribution in the Denisovan or the two European Neanderthals. We conclude that in addition to later interbreeding events, the ancestors of Neanderthals from the Altai Mountains and early modern humans met and interbred, possibly in the Near East, many thousands of years earlier than previously thought.

Ion conducting membranes for aqueous flow battery systems.

PubMed

Yuan, Zhizhang; Zhang, Huamin; Li, Xianfeng

2018-06-07

Flow batteries, aqueous flow batteries in particular, are the most promising candidates for stationary energy storage to realize the wide utilization of renewable energy sources. To meet the requirement of large-scale energy storage, there has been a growing interest in aqueous flow batteries, especially in novel redox couples and flow-type systems. However, the development of aqueous flow battery technologies is at an early stage and their performance can be further improved. As a key component of a flow battery, the membrane has a significant effect on battery performance. Currently, the membranes used in aqueous flow battery technologies are very limited. In this feature article, we first cover the application of porous membranes in vanadium flow battery technology, and then the membranes in most recently reported aqueous flow battery systems. Meanwhile, we hope that this feature article will inspire more efforts to design and prepare membranes with outstanding performance and stability, and then accelerate the development of flow batteries for large scale energy storage applications.

Emplacement of Basaltic Lava Flows: the Legacy of GPL Walker

NASA Astrophysics Data System (ADS)

Cashman, K. V.

2005-12-01

Through his early field measurements of lava flow morphology, G.P.L. Walker established a framework for examination of the dynamics of lava flow emplacement that is still in place today. I will examine this legacy as established by three early papers: (1) his 1967 paper, where he defined a relationship between the thickness of recent Etna lava flows and the slope over which they flowed, a relationship that he ascribed to lava viscosity; (2) his 1971 paper, which defined a relationship between lava flux and the formation of simple and compound flow units that he used to infer high effusion rates for the emplacement of some flood basalt lavas; and (3) his often-cited 1973 paper, which related the length of lava flows to their average effusion rate. These three papers, all similar in their basic approach of using field measurements of lava flow morphology to extract fundamental relationships between eruption conditions (magma flux and rheology) and emplacement style (flow length and thickness), firmly established the relationship between flow morphology and emplacement dynamics that has since been widely applied not only to subaerial lava flows, but also to the interpretation of flows in submarine and planetary environments. Important extensions of these concepts have been provided by improved field observation methods, particularly for analysis of flowing lava, by laboratory measurements of lava rheology, by the application of analog experiments to lava flow dynamics, and by steady improvement of numerical techniques to model the flow of lava over complex terrain. The real legacy of G.P.L. Walker's field measurement approach, however, may lie in the future, as new topographic measurement techniques such as LIDAR hold exciting promise for truly quantitative analysis of lava flow morphologies and their relationship to flow dynamics.

Early first trimester uteroplacental flow and the progressive disintegration of spiral artery plugs: new insights from contrast-enhanced ultrasound and tissue histopathology.

PubMed

Roberts, V H J; Morgan, T K; Bednarek, P; Morita, M; Burton, G J; Lo, J O; Frias, A E

2017-12-01

Does the use of a vascular contrast agent facilitate earlier detection of maternal flow to the placental intervillous space (IVS) in the first trimester of pregnancy? Microvascular filling of the IVS was demonstrated by contrast-enhanced ultrasound from 6 weeks of gestation onwards, earlier than previously believed. During placental establishment and remodeling of maternal spiral arteries, endovascular trophoblast cells invade and accumulate in the lumen of these vessels to form 'trophoblast plugs'. Prior evidence from morphological and Doppler ultrasound studies has been conflicting as to whether the spiral arteries are completely plugged, preventing maternal blood flow to the IVS until late in the first trimester. Uteroplacental flow was examined across the first trimester in human subjects given an intravenous infusion of lipid-shelled octofluoropropane microbubbles with ultrasound measurement of destruction and replenishment kinetics. We also performed a comprehensive histopathological correlation using two separately archived uteroplacental tissue collections to evaluate the degree of spiral artery plugging and evaluate remodeling of the upstream myometrial radial and arcurate arteries. Pregnant women (n = 34) were recruited in the first trimester (range: 6+3 to 13+6 weeks gestation) for contrast-enhanced ultrasound studies with destruction-replenishment analysis of signal intensity for assessment of microvascular flux rate. Histological samples from archived in situ (Boyd Collection, n = 11) and fresh first, second, and third trimester decidual and post-hysterectomy uterine specimens (n = 16) were evaluated by immunohistochemistry (using markers of epithelial, endothelial and T-cells, as well as cell adhesion and proliferation) and ultrastructural analysis. Contrast agent entry into the IVS was visualized as early as 6+3 weeks of gestation with some variability in microvascular flux rate noted in the 6-7+6 week samples. Spiral artery plug canalization was

Early signs that predict later haemodynamically significant patent ductus arteriosus.

PubMed

Engür, Defne; Deveci, Murat; Türkmen, Münevver K

2016-03-01

Our aim was to determine the optimal cut-off values, sensitivity, specificity, and diagnostic power of 12 echocardiographic parameters on the second day of life to predict subsequent ductal patency. We evaluated preterm infants, born at ⩽32 weeks of gestation, starting on their second day of life, and they were evaluated every other day until ductal closure or until there were clinical signs of re-opening. We measured transductal diameter; pulmonary arterial diastolic flow; retrograde aortic diastolic flow; pulsatility index of the left pulmonary artery and descending aorta; left atrium and ventricle/aortic root ratio; left ventricular output; left ventricular flow velocity time integral; mitral early/late diastolic flow; and superior caval vein diameter and flow as well as performed receiver operating curve analysis. Transductal diameter (>1.5 mm); pulmonary arterial diastolic flow (>25.6 cm/second); presence of retrograde aortic diastolic flow; ductal diameter by body weight (>1.07 mm/kg); left pulmonary arterial pulsatility index (⩽0.71); and left ventricle to aortic root ratio (>2.2) displayed high sensitivity and specificity (p0.9). Parameters with moderate sensitivity and specificity were as follows: left atrial to aortic root ratio; left ventricular output; left ventricular flow velocity time integral; and mitral early/late diastolic flow ratio (p0.05) had low diagnostic value. Left pulmonary arterial pulsatility index, left ventricle/aortic root ratio, and ductal diameter by body weight are useful adjuncts offering a broader outlook for predicting ductal patency.

Pulsatile spiral blood flow through arterial stenosis.

PubMed

Linge, Fabian; Hye, Md Abdul; Paul, Manosh C

2014-11-01

Pulsatile spiral blood flow in a modelled three-dimensional arterial stenosis, with a 75% cross-sectional area reduction, is investigated by using numerical fluid dynamics. Two-equation k-ω model is used for the simulation of the transitional flow with Reynolds numbers 500 and 1000. It is found that the spiral component increases the static pressure in the vessel during the deceleration phase of the flow pulse. In addition, the spiral component reduces the turbulence intensity and wall shear stress found in the post-stenosis region of the vessel in the early stages of the flow pulse. Hence, the findings agree with the results of Stonebridge et al. (2004). In addition, the results of the effects of a spiral component on time-varying flow are presented and discussed along with the relevant pathological issues.

The impact of cardiac rhythm on the mitral valve area and gradient in patients with mitral stenosis.

PubMed

Arı, Hasan; Arı, Selma; Karakuş, Alper; Camcı, Sencer; Doğanay, Kübra; Tütüncü, Ahmet; Melek, Mehmet; Bozat, Tahsin

2017-08-01

The aim of this study was to evaluate the effect of cardiac rhythm on the echocardiographic mitral valve area (MVA) and transmitral gradient calculation in relation to net atrioventricular compliance (Cn). Patients (n=22) with mild or moderate pure rheumatic mitral stenosis (MS) (MVA <2 cm2 and MVA >1 cm2) and atrial fibrillation (AF) were evaluated. All patients underwent transthoracic electrical DC cardioversion under amiodarone treatment. Nineteen of the 22 patients were successfully converted to sinus rhythm (SR). The patients were evaluated with transthoracic echocardiography before and two to three days after DC cardioversion. In order to deal with variable R-R intervals, the measurements were averaged on five to eight consecutive beats in AF. Cn was calculated with a previously validated equation [Cn (mL/mm Hg)=1.270 x MVA/E-wave downslope]. The Cn difference between AF and SR was calculated as follows: [(AF Cn-SR Cn)/AF Cn] x 100. The percentage gradient (mean or maximal) difference between AF and SR was calculated as follows: [AF gradient (mean or maximal) - SR gradient (mean or maximal)]/[AF gradient (mean or maximal)] x 100. The MVA was lower (MVA planimetric; 1.62±0.29 vs. 1.54±0.27; p=.003, MVA PHT; 1.66±0.30 vs. 1.59±0.26; p=0.01) but transmitral gradient (mean gradient; 6.49±2.51 vs. 8.89±3.52; p=0.001, maximal gradient: 16.94±5.11 vs. 18.57±4.54; p=0.01) and Cn values (5.37±0.77 vs. 6.26±0.64; p<0.001) were higher in the AF than SR. There was a significant correlation between Cn difference and transmitral gradient difference (mean and maximal) (Cn difference-mean gradient difference; r=0.46; p=0.05; Cn difference-maximal gradient difference; r=0.72; p=0.001). Cardiac rhythm has a significant impact on echocardiographic evaluation of MVA, transmitral gradient, and Cn in patients with MS.

Sources of sound in fluid flows

NASA Technical Reports Server (NTRS)

Williams, J. E. F.

1974-01-01

Some features of a flow that produce acoustic radiation, particularly when the flow is turbulent and interacting with solid surfaces such as turbine or compressor blades are discussed. Early theoretical ideas on the subject are reviewed and are shown to be inadequate at high Mach number. Some recent theoretical developments that form the basis of a description of sound generation by supersonic flows interacting with surfaces are described. At high frequencies the problem is treated as one of describing the surface-induced diffraction field of adjacent aerodynamic quadrupole sources. This approach has given rise to distinctly new features of the problem that seem to have bearing on the radiating properties of relatively large aerodynamic surfaces.

Flow cytogenetics and chromosome sorting.

PubMed

Cram, L S

1990-06-01

This review of flow cytogenetics and chromosome sorting provides an overview of general information in the field and describes recent developments in more detail. From the early developments of chromosome analysis involving single parameter or one color analysis to the latest developments in slit scanning of single chromosomes in a flow stream, the field has progressed rapidly and most importantly has served as an important enabling technology for the human genome project. Technological innovations that advanced flow cytogenetics are described and referenced. Applications in basic cell biology, molecular biology, and clinical investigations are presented. The necessary characteristics for large number chromosome sorting are highlighted. References to recent review articles are provided as a starting point for locating individual references that provide more detail. Specific references are provided for recent developments.

Uterine artery blood flow, fetal hypoxia and fetal growth

PubMed Central

Browne, Vaughn A.; Julian, Colleen G.; Toledo-Jaldin, Lillian; Cioffi-Ragan, Darleen; Vargas, Enrique; Moore, Lorna G.

2015-01-01

Evolutionary trade-offs required for bipedalism and brain expansion influence the pregnancy rise in uterine artery (UtA) blood flow and, in turn, reproductive success. We consider the importance of UtA blood flow by reviewing its determinants and presenting data from 191 normotensive (normal, n = 125) or hypertensive (preeclampsia (PE) or gestational hypertension (GH), n = 29) Andean residents of very high (4100–4300 m) or low altitude (400 m, n = 37). Prior studies show that UtA blood flow is reduced in pregnancies with intrauterine growth restriction (IUGR) but whether the IUGR is due to resultant fetal hypoxia is unclear. We found higher UtA blood flow and Doppler indices of fetal hypoxia in normotensive women at high versus low altitude but similar fetal growth. UtA blood flow was markedly lower in early-onset PE versus normal high-altitude women, and their fetuses more hypoxic as indicated by lower fetal heart rate, Doppler indices and greater IUGR. We concluded that, despite greater fetal hypoxia, fetal growth was well defended by higher UtA blood flows in normal Andeans at high altitude but when compounded by lower UtA blood flow in early-onset PE, exaggerated fetal hypoxia caused the fetus to respond by decreasing cardiac output and redistributing blood flow to help maintain brain development at the expense of growth elsewhere. We speculate that UtA blood flow is not only an important supply line but also a trigger for stimulating the metabolic and other processes regulating feto-placental metabolism and growth. Studies using the natural laboratory of high altitude are valuable for identifying the physiological and genetic mechanisms involved in human reproductive success. PMID:25602072

Intraoperative Portal Flow of Less Than 1 Liter per Minute After Orthotopic Liver Transplantation Is Not Associated Per Se With an Increased Rate of Early Graft Dysfunction.

PubMed

Gastaca, M; Prieto, M; Valdivieso, A; Ruiz, P; Ventoso, A; Palomares, I; Matarranz, A; Martinez-Indart, L; Ortiz de Urbina, J

2016-09-01

The aim of this study was to determine whether a portal flow of <1,000 mL/min in orthotopic liver transplantation (OLT) is associated with a higher incidence of early graft dysfunction (EGD) and graft loss. A retrospective study was performed of 540 OLTs carried out consecutively from December 2004 to December 2013. Patients were divided into 2 groups: group A, portal flow <1,000 mL/min; and group B, portal flow >1,000 mL/min. We studied the incidence of EGD and graft survival. A subanalysis was performed to define the minimum acceptable portal flow/100 g of liver weight to reduce the development EGD and graft loss. Group A included 29 patients and group B, 511 patients. Group A had significantly lower-weight donors and recipients, female recipients with cholestatic disease, lower MELD scores, and lower hepatic artery flow. EGD occurred in 7 patients in group A (24.1%) versus 101 patients in group B (19.8%; P = .43). No significant differences were found in 1- and 5-year graft survival. A portal flow of <80 mL/min/100 g of liver weight was related to a significantly higher risk of developing EGD (odds ratio, 4.35; 95% confidence interval [CI], 1.46-12.91; P = .008) and graft loss (hazard ratio, 4.05; 95% CI, 1.32-12.42; P = .014). Intraoperative portal flow of <1,000 mL/min in OLT was not related per se with a higher incidence of EGD or graft loss. Significantly higher risk of developing EGD and graft loss was associated with a portal flow of <80 mL/min/100 g of liver weight. Copyright © 2016 Elsevier Inc. All rights reserved.

Cardiac structure and function and dependency in the oldest old.

PubMed

Leibowitz, David; Jacobs, Jeremy M; Stessman-Lande, Irit; Cohen, Aharon; Gilon, Dan; Ein-Mor, Eliana; Stessman, Jochanan

2011-08-01

To examine the association between cardiac function and activities of daily living (ADLs) in an age-homogenous, community-dwelling population born in 1920 and 1921. Cross-sectional analysis of a prospective cohort study. Community-dwelling elderly population. Participants were recruited from the Jerusalem Longitudinal Cohort Study, which has followed an age-homogenous cohort of Jerusalem residents born in 1920 and 1921. Four hundred eighty-nine of the participants (228 male, 261 female) from the most recent set of data collection in 2005 and 2006 underwent echocardiography at their place of residence in addition to structured interviews and physical examination. A home-based comprehensive assessment was performed to assess health and functional status, including performance of ADLs. Dependence was defined as needing assistance with one or more basic ADLs. Standard echocardiographic assessment of cardiac structure and function, including ejection fraction (EF) and diastolic function as assessed using early diastolic mitral annular tissue velocity measurements obtained using tissue Doppler, was performed. Of the participants with limitation in at least one ADL, significantly more had low EF (< 55%) than the group that was independent (52.6 % vs 39.1%; P=.01). In addition, participants with dependence in ADL had higher left ventricular mass index (LVMI) (129.3 vs 119.7 g/m²) and left atrial volume index (LAVI) (41.3 vs 36.7 mL/m²). There were no differences between the groups in percentage of participants with impaired diastolic function or average ratio of early diastolic transmitral flow velocity to early diastolic mitral annular tissue velocity (11.5 vs 11.8; P=.64). In this age-homogenous cohort of the oldest old, high LVMI and LAVI and indices of systolic but not diastolic function as assessed according to Doppler were associated with limitations in ADLs. © 2011, Copyright the Authors. Journal compilation © 2011, The American Geriatrics Society.

Generation of anti-porcine CD69 monoclonal antibodies and their usefulness to evaluate early activation of cellular immunity by flow cytometric analysis.

PubMed

Hayashi, Yumiko; Okutani, Mie; Ogawa, Shohei; Tsukahara, Takamitsu; Inoue, Ryo

2018-05-01

T cell-mediated cellular immunity and humoral immunity are equally important for the prevention of diseases. To assess activation of human and mouse cellular immunity, early activation markers of lymphocytes are often used in flow cytometry targeting expression of CD69 molecules. Response of humoral immunity against infection or vaccination has been well investigated in pigs, but that of cellular immunity has been largely neglected due to lack of direct evaluation tools. Thus, in pig research a proper assay of antibody reacted with porcine CD69 is still unavailable. In the present study, two anti-porcine CD69 mAb-producing mouse hybridomas, 01-14-22-51 (IgG2b-κ) and 01-22-44-102 (IgG2a-κ), both showing fine reactivity with phorbol 12-myristate 13-acetate (PMA) and ionomycin-stimulated porcine peripheral blood lymphocytes in flow cytometry, were established. When porcine peripheral blood lymphocytes were activated with PMA and ionomycin and analyzed by flow cytometry, it was found that both mAbs generated in this study stained about 70% of lymphocytes. In contrast, after an identical procedure, only 5% and 13.5% of lymphocytes were stained with anti-interferon-γ mAb and anti-tumor necrosis factor-α mAb, respectively. These results indicate that evaluation of cellular immunity activation turns more sensitive after using our newly generated mAbs. © 2018 Japanese Society of Animal Science.

Chemically non-equilibrated QGP and thermal photon elliptic flow

NASA Astrophysics Data System (ADS)

Monnai, Akihiko

2016-07-01

It has been discovered in recent heavy-ion experiments that elliptic and triangular flow of direct photons are underpredicted by most hydrodynamic models. I discuss possible enhancement mechanisms based on late chemical equilibration of the QGP and in-medium modification of parton distributions. Numerical hydrodynamic analyses indicate that they suppress early photon emission and visibly enhance thermal photon elliptic flow.

Maximal blood flow acceleration analysis in the early diastolic phase for aortocoronary artery bypass grafts: a new transit-time flow measurement predictor of graft failure following coronary artery bypass grafting.

PubMed

Handa, Takemi; Orihashi, Kazumasa; Nishimori, Hideaki; Yamamoto, Masaki

2016-11-01

Maximal graft flow acceleration (max df/dt) determined using transit-time flowmetry (TTFM) in the diastolic phase was assessed as a potential predictor of graft failure for aortocoronary artery (AC) bypass grafts in coronary artery bypass patients. Max df/dt was retrospectively measured in 114 aortocoronary artery bypass grafts. TTFM data were fitted to a 9-polynomial curve, which was derived from the first-derivative curve, to measure max df/dt (9-polynomial max df/dt). Abnormal TTFM was defined as a mean flow of <15 ml/min, a pulsatility index of >5 or a diastolic filling ratio of <50 %. Postoperative assessments were routinely performed by coronary artery angiography (CAG) at 1 year after surgery. Using TTFM, 68 grafts were normal, 4 of which were failing on CAG, and 46 grafts were abnormal, 21 of which were failing on CAG. 9-polynomial max df/dt was significantly lower in abnormal TTFM/failing by the CAG group compared with abnormal TTFM/patent by the CAG group (1.08 ± 0.89 vs. 2.05 ± 1.51 ml/s(2), respectively; P < 0.01, Mann-Whitney U test, Holm adjustment). TTFM 9-polynomial max df/dt in the early diastolic phase may be a promising predictor of future graft failure for AC bypass grafts, particularly in abnormal TTFM grafts.

Early harvesting of the vascularized pedicled nasoseptal flap during endoscopic skull base surgery.

PubMed

Eloy, Jean Anderson; Patel, Amit A; Shukla, Pratik A; Choudhry, Osamah J; Liu, James K

2013-01-01

The vascularized pedicled nasoseptal flap (PNSF) represents a successful option for reconstruction of large skull base defects after expanded endoscopic endonasal approaches (EEA). This vascularized flap can be harvested early or late in the operation depending on the anticipation of high-flow CSF leaks. Each harvesting technique (early vs. late) is associated with different advantages and disadvantages. In this study, we evaluate our experience with early harvesting of the PNSF for repair of large skull base defects after EEA. A retrospective review was performed at a tertiary care medical center on patients who underwent early PNSF harvesting during reconstruction of intraoperative high-flow CSF leaks after EEA between December 2008 and March 2012. Demographic data, repair materials, surgical approach, and incidence of PNSF usage were collected. Eighty-seven patients meeting the inclusion criteria were identified. In 86 procedures (98.9%), the PNSF harvested at the beginning of the operation was used. In 1 case (1.1%), the PNSF was not used because a high-flow intraoperative CSF leak was not encountered. This patient had recurrence of intradural disease 8months later, and the previously elevated PNSF was subsequent used after tumor resection. Based on our data, a high-flow CSF leak and need for a PNSF can be accurately anticipated in patients undergoing EEA for skull base lesions. Because of the advantages of early harvesting of the PNSF and the high preoperative predictive value of CSF leak anticipations, this technique represents a feasible harvesting practice for EEA surgeries. Copyright © 2013 Elsevier Inc. All rights reserved.

Geometry: A Flow Proof Approach.

ERIC Educational Resources Information Center

McMurray, Robert

The inspiration for this text was provided by an exposure to the flow proof approach to a proof format as opposed to the conventional two-column approach. Historical background is included, to provide a frame of reference to give the student an appreciation of the subject. The basic constructions are introduced early and briefly, to aid the…

Masks in Imaging Flow Cytometry

PubMed Central

Dominical, Venina; Samsel, Leigh; McCoy, J. Philip

2016-01-01

Data analysis in imaging flow cytometry incorporates elements of flow cytometry together with other aspects of morphological analysis of images. A crucial early step in this analysis is the creation of a mask to distinguish the portion of the image upon which further examination of specified features can be performed. Default masks are provided by the manufacturer of the imaging flow cytometer but additional custom masks can be created by the individual user for specific applications. Flawed or inaccurate masks can have a substantial negative impact on the overall analysis of a sample, thus great care must be taken to ensure the accuracy of masks. Here we discuss various types of masks and cite examples of their use. Furthermore we provide our insight for how to approach selecting and assessing the optimal mask for a specific analysis. PMID:27461256

Supersonic reacting internal flow fields

NASA Technical Reports Server (NTRS)

Drummond, J. Philip

1989-01-01

The national program to develop a trans-atmospheric vehicle has kindled a renewed interest in the modeling of supersonic reacting flows. A supersonic combustion ramjet, or scramjet, has been proposed to provide the propulsion system for this vehicle. The development of computational techniques for modeling supersonic reacting flow fields, and the application of these techniques to an increasingly difficult set of combustion problems are studied. Since the scramjet problem has been largely responsible for motivating this computational work, a brief history is given of hypersonic vehicles and their propulsion systems. A discussion is also given of some early modeling efforts applied to high speed reacting flows. Current activities to develop accurate and efficient algorithms and improved physical models for modeling supersonic combustion is then discussed. Some new problems where computer codes based on these algorithms and models are being applied are described.

Application and analysis of debris-flow early warning system in Wenchuan earthquake-affected area

NASA Astrophysics Data System (ADS)

Liu, D. L.; Zhang, S. J.; Yang, H. J.; Zhao, L. Q.; Jiang, Y. H.; Tang, D.; Leng, X. P.

2016-02-01

The activities of debris flow (DF) in the Wenchuan earthquake-affected area significantly increased after the earthquake on 12 May 2008. The safety of the lives and property of local people is threatened by DFs. A physics-based early warning system (EWS) for DF forecasting was developed and applied in this earthquake area. This paper introduces an application of the system in the Wenchuan earthquake-affected area and analyzes the prediction results via a comparison to the DF events triggered by the strong rainfall events reported by the local government. The prediction accuracy and efficiency was first compared with a contribution-factor-based system currently used by the weather bureau of Sichuan province. The storm on 17 August 2012 was used as a case study for this comparison. The comparison shows that the false negative rate and false positive rate of the new system is, respectively, 19 and 21 % lower than the system based on the contribution factors. Consequently, the prediction accuracy is obviously higher than the system based on the contribution factors with a higher operational efficiency. On the invitation of the weather bureau of Sichuan province, the authors upgraded their prediction system of DF by using this new system before the monsoon of Wenchuan earthquake-affected area in 2013. Two prediction cases on 9 July 2013 and 10 July 2014 were chosen to further demonstrate that the new EWS has high stability, efficiency, and prediction accuracy.

Chemotherapeutic drug-specific alteration of microvascular blood flow in murine breast cancer as measured by diffuse correlation spectroscopy

PubMed Central

Ramirez, Gabriel; Proctor, Ashley R.; Jung, Ki Won; Wu, Tong Tong; Han, Songfeng; Adams, Russell R.; Ren, Jingxuan; Byun, Daniel K.; Madden, Kelley S.; Brown, Edward B.; Foster, Thomas H.; Farzam, Parisa; Durduran, Turgut; Choe, Regine

2016-01-01

The non-invasive, in vivo measurement of microvascular blood flow has the potential to enhance breast cancer therapy monitoring. Here, longitudinal blood flow of 4T1 murine breast cancer (N=125) under chemotherapy was quantified with diffuse correlation spectroscopy based on layer models. Six different treatment regimens involving doxorubicin, cyclophosphamide, and paclitaxel at clinically relevant doses were investigated. Treatments with cyclophosphamide increased blood flow as early as 3 days after administration, whereas paclitaxel induced a transient blood flow decrease at 1 day after administration. Early blood flow changes correlated strongly with the treatment outcome and distinguished treated from untreated mice individually for effective treatments. PMID:27699124

A classification scheme for the morphology of lava flow fields

NASA Technical Reports Server (NTRS)

Wilson, L.; Pinkerton, H.; Head, James W.; Roberts, K. Magee

1993-01-01

Analysis of the processes controlling the advance of lava flows shows that, if no other factors intervene, thermal constraints will act to limit the maximum length of a flow being fed at a given volume or mass effusion rate from a vent. These constraints can be characterized through the Gratz number, which takes on a large value at the vent and decreases down flow. Early application of this principle showed that, despite the many subtleties of modes of heat loss from flows, motion apparently ceases when the Gratz number has decreased to a value close to 300. Recent analyses of flow units from the 1983-86 Pu'u 'O'o eruption of Kilauea and of other, more silicic lava flow units confirm this finding.

Resource Prospector Propulsion Cold Flow Test

NASA Technical Reports Server (NTRS)

Williams, Hunter; Pederson, Kevin; Dervan, Melanie; Holt, Kimberly; Jernigan, Frankie; Trinh, Huu; Flores, Sam

2014-01-01

For the past year, NASA Marshall Space Flight Center and Johnson Space Center have been working on a government version of a lunar lander design for the Resource Prospector Mission. A propulsion cold flow test system, representing an early flight design of the propulsion system, has been fabricated. The primary objective of the cold flow test is to simulate the Resource Prospector propulsion system operation through water flow testing and obtain data for anchoring analytical models. This effort will also provide an opportunity to develop a propulsion system mockup to examine hardware integration to a flight structure. This paper will report the work progress of the propulsion cold flow test system development and test preparation. At the time this paper is written, the initial waterhammer testing is underway. The initial assessment of the test data suggests that the results are as expected and have a similar trend with the pretest prediction. The test results will be reported in a future conference.

Role of Myocardial Collagen in Severe Aortic Stenosis With Preserved Ejection Fraction and Symptoms of Heart Failure.

PubMed

Echegaray, Kattalin; Andreu, Ion; Lazkano, Ane; Villanueva, Iñaki; Sáenz, Alberto; Elizalde, María Reyes; Echeverría, Tomás; López, Begoña; Garro, Asier; González, Arantxa; Zubillaga, Elena; Solla, Itziar; Sanz, Iñaki; González, Jesús; Elósegui-Artola, Alberto; Roca-Cusachs, Pere; Díez, Javier; Ravassa, Susana; Querejeta, Ramón

2017-10-01

We investigated the anatomical localization, biomechanical properties, and molecular phenotype of myocardial collagen tissue in 40 patients with severe aortic stenosis with preserved ejection fraction and symptoms of heart failure. Two transmural biopsies were taken from the left ventricular free wall. Mysial and nonmysial regions of the collagen network were analyzed. Myocardial collagen volume fraction (CVF) was measured by picrosirius red staining. Young's elastic modulus (YEM) was measured by atomic force microscopy in decellularized slices to assess stiffness. Collagen types I and III were measured as C I VF and C III VF, respectively, by confocal microscopy in areas with YEM evaluation. Compared with controls, patients exhibited increased mysial and nonmysial CVF and nonmysial:mysial CVF ratio (P < .05). In patients, nonmysial CVF (r = 0.330; P = .046) and the nonmysial:mysial CVF ratio (r = 0.419; P = .012) were directly correlated with the ratio of maximal early transmitral flow velocity in diastole to early mitral annulus velocity in diastole. Both the C I VF:C III VF ratio and YEM were increased (P ≤ .001) in nonmysial regions compared with mysial regions in patients, with a direct correlation (r = 0.895; P < .001) between them. These findings suggest that, in patients with severe aortic stenosis with preserved ejection fraction and symptoms of heart failure, diastolic dysfunction is associated with increased nonmysial deposition of collagen, predominantly type I, resulting in increased extracellular matrix stiffness. Therefore, the characteristics of collagen tissue may contribute to diastolic dysfunction in these patients. Copyright © 2016 Sociedad Española de Cardiología. Published by Elsevier España, S.L.U. All rights reserved.

Diastolic left ventricular function in preterm infants with a patent ductus arteriosus: a serial Doppler echocardiography study.

PubMed

Schmitz, Lothar; Stiller, Brigitte; Koch, Heike; Koehne, Petra; Lange, Peter

2004-02-01

In very low birth weight neonates, a left-to-right shunt via persistent ductus arteriosus (PDA) may interact with diastolic left ventricular function, but specific changes of Doppler parameters have yet to be reported. In a serial transmitral Doppler study, we investigated the impact of a PDA on diastolic function parameters. Twenty-two patients with and without PDA were examined on day 3.8+/-1 and day 14+/-2 after birth. By the first examination, 13 out of 22 patients had a PDA; by the second examination, the number was still 8 out of 22. Peak early and atrial flow velocities (44.8+/-15 and 50.1+/-13 cm/s, respectively) were higher (p<0.05) for neonates with PDA compared to those with closed duct (30.9+/-6 and 34.2 cm/s, respectively). Isovolumic relaxation time (IVRT) was shorter in neonates with PDA (45+/-7 ms, N=21) compared to those with a closed duct (55.3+/-5 ms, N=23) (p<0.01). IVRT correlated inversely with cardiac index (R=-0.79, p<0.01). All observed changes reversed to the normal range after closure of the PDA. When premature infants with a PDA experience a preload challenge, early and atrial peak velocities increase and IVRT shortens significantly. This coincidence of elevated transvalvular pressure differences and decreased IVRT in neonates with immature diastolic function can best be explained as a result of left atrial pressure elevation. Consequently, pulmonary venous pressure must be elevated, with its inherent effect on pulmonary capillary physiology. Thus, the monitoring of left ventricular diastolic function adds significant information to the care of preterm infants with a PDA.

Microfluidic Impedance Flow Cytometry Enabling High-Throughput Single-Cell Electrical Property Characterization

PubMed Central

Chen, Jian; Xue, Chengcheng; Zhao, Yang; Chen, Deyong; Wu, Min-Hsien; Wang, Junbo

2015-01-01

This article reviews recent developments in microfluidic impedance flow cytometry for high-throughput electrical property characterization of single cells. Four major perspectives of microfluidic impedance flow cytometry for single-cell characterization are included in this review: (1) early developments of microfluidic impedance flow cytometry for single-cell electrical property characterization; (2) microfluidic impedance flow cytometry with enhanced sensitivity; (3) microfluidic impedance and optical flow cytometry for single-cell analysis and (4) integrated point of care system based on microfluidic impedance flow cytometry. We examine the advantages and limitations of each technique and discuss future research opportunities from the perspectives of both technical innovation and clinical applications. PMID:25938973

Travelling Policy Reforms Reconfiguring the Work of Early Childhood Educators in Australia

ERIC Educational Resources Information Center

Nuttall, Joce; Thomas, Louise; Wood, Elizabeth

2014-01-01

Interventions in the field of early childhood education policy, drawn from global policy flows, are reconfiguring the work of early childhood educators in Australia. One such intervention is the requirement to designate an "educational leader" (EL) in each service for young children and their families. This policy intervention has its…

Active control of Boundary Layer Separation & Flow Distortion in Adverse Pressure Gradient Flows via Supersonic Microjets

NASA Technical Reports Server (NTRS)

Alvi, Farrukh S.; Gorton, Susan (Technical Monitor)

2005-01-01

Inlets to aircraft propulsion systems must supply flow to the compressor with minimal pressure loss, flow distortion or unsteadiness. Flow separation in internal flows such as inlets and ducts in aircraft propulsion systems and external flows such as over aircraft wings, is undesirable as it reduces the overall system performance. The aim of this research has been to understand the nature of separation and more importantly, to explore techniques to actively control this flow separation. In particular, the use of supersonic microjets as a means of controlling boundary layer separation was explored. The geometry used for the early part of this study was a simple diverging Stratford ramp, equipped with arrays of supersonic microjets. Initial results, based on the mean surface pressure distribution, surface flow visualization and Planar Laser Scattering (PLS) indicated a reverse flow region. We implemented supersonic microjets to control this separation and flow visualization results appeared to suggest that microjets have a favorable effect, at least to a certain extent. However, the details of the separated flow field were difficult to determine based on surface pressure distribution, surface flow patterns and PLS alone. It was also difficult to clearly determine the exact influence of the supersonic microjets on this flow. In the latter part of this study, the properties of this flow-field and the effect of supersonic microjets on its behavior were investigated in further detail using 2-component (planar) Particle Image Velocimetry (PIV). The results clearly show that the activation of microjets eliminated flow separation and resulted in a significant increase in the momentum of the fluid near the ramp surface. Also notable is the fact that the gain in momentum due to the elimination of flow separation is at least an order of magnitude larger (two orders of magnitude larger in most cases) than the momentum injected by the microjets and is accomplished with very

Effects of curvature on rarefied gas flows between rotating concentric cylinders

NASA Astrophysics Data System (ADS)

Dongari, Nishanth; White, Craig; Scanlon, Thomas J.; Zhang, Yonghao; Reese, Jason M.

2013-05-01

The gas flow between two concentric rotating cylinders is considered in order to investigate non-equilibrium effects associated with the Knudsen layers over curved surfaces. We investigate the nonlinear flow physics in the near-wall regions using a new power-law (PL) wall-scaling approach. This PL model incorporates Knudsen layer effects in near-wall regions by taking into account the boundary limiting effects on the molecular free paths. We also report new direct simulation Monte Carlo results covering a wide range of Knudsen numbers and accommodation coefficients, and for various outer-to-inner cylinder radius ratios. Our simulation data are compared with both the classical slip flow theory and the PL model, and we find that non-equilibrium effects are not only dependent on Knudsen number and accommodation coefficient but are also significantly affected by the surface curvature. The relative merits and limitations of both theoretical models are explored with respect to rarefaction and curvature effects. The PL model is able to capture some of the nonlinear trends associated with Knudsen layers up to the early transition flow regime. The present study also illuminates the limitations of classical slip flow theory even in the early slip flow regime for higher curvature test cases, although the model does exhibit good agreement throughout the slip flow regime for lower curvature cases. Torque and velocity profile comparisons also convey that a good prediction of integral flow properties does not necessarily guarantee the accuracy of the theoretical model used, and it is important to demonstrate that field variables are also predicted satisfactorily.

Promoting free flow in the networks: Reimagining the body in early modern Suzhou.

PubMed

Scheid, Volker

2017-06-01

The history of Chinese medicine is still widely imagined in terms dictated by the discourse of modernity, that is as 'traditional' and 'Chinese.' And yet, so as to be intelligible to us moderns, it must simultaneously be framed through categories that make it comparable somehow to the 'West' and the 'modern' from which it is said to be essentially different. This is accomplished, for instance, by viewing Chinese medicine as fundamentally shaped by cosmological thinking, as focusing on process rather than matter, and as forever hampered by attachments to the past even when it tries to innovate. At the same time, it is described as pursuing its objectives in ways that make sense in 'our' terms, too, such as the goal of creating physiological homeostasis through methods of supplementation and drainage. In this paper, I seek to move beyond this kind of analysis through a two-pronged approach. First, by focusing on the concept of tong - a character that calls forth images of free flow, connectivity, relatedness and understanding - I foreground an important aspect of Chinese medical thinking and practice that has virtually been ignored by Western historians of medicine and science. Second, by exploring how the influential physician Ye Tianshi (1664-1746) employed tong to advance medical thinking and practice at a crucial moment of change in the history of Chinese medicine, I demonstrate that physicians in early modern China moved towards new understandings of the body readily intelligible by modern biomedical anatomy. I argue that this mode of analysis allows us to transcend the limitations inherent in the current historiography of Chinese medicine: because it allows for comparison to emerge from our subject matter rather than imposing our imaginaries onto it in advance.

Modeling lateral circulation and its influence on the along-channel flow in a branched estuary

NASA Astrophysics Data System (ADS)

Zhu, Lei; He, Qing; Shen, Jian

2018-02-01

A numerical modeling study of the influence of the lateral flow on the estuarine exchange flow was conducted in the north passage of the Changjiang estuary. The lateral flows show substantial variabilities within a flood-ebb tidal cycle. The strong lateral flow occurring during flood tide is caused primarily by the unique cross-shoal flow that induces a strong northward (looking upstream) barotropic force near the surface and advects saltier water toward the northern part of the channel, resulting in a southward baroclinic force caused by the lateral density gradient. Thus, a two-layer structure of lateral flows is produced during the flood tide. The lateral flows are vigorous near the flood slack and the magnitude can exceed that of the along-channel tidal flow during that period. The strong vertical shear of the lateral flows and the salinity gradient in lateral direction generate lateral tidal straining, which are out of phase with the along-channel tidal straining. Consequently, stratification is enhanced at the early stage of the ebb tide. In contrast, strong along-channel straining is apparent during the late ebb tide. The vertical mixing disrupts the vertical density gradient, thus suppressing stratification. The impact of lateral straining on stratification during spring tide is more pronounced than that of along-channel straining during late flood and early ebb tides. The momentum balance along the estuary suggests that lateral flow can augment the residual exchange flow. The advection of lateral flows brings low-energy water from the shoal to the deep channel during the flood tide, whereas the energetic water is moved to the shoal via lateral advection during the ebb tide. The impact of lateral flow on estuarine circulation of this multiple-channel estuary is different from single-channel estuary. A model simulation by blocking the cross-shoal flow shows that the magnitudes of lateral flows and tidal straining are reduced. Moreover, the reduced lateral

Axial and radial water flow in the trunks of oak trees: a quantitative and qualitative analysis.

PubMed

Granier, A; Anfodillo, T; Sabatti, M; Cochard, H; Dreyer, E; Tomasi, M; Valentini, R; Bréda, N

1994-12-01

Axial water flow in the trunks of mature oak trees (Quercus petraea (Matt.) Liebl. and Q. robur L.) was studied by four independent techniques: water absorption from a cut trunk, sap flowmeters, heat pulse velocity (HPV) and thermoimaging. Estimation of the total water flow with sap flowmeters, HPV and water absorption yielded comparable results. We concluded from dye colorations, thermograms and axial profiles of sap flow and heat pulse velocity that, in intact trunks, most of the flow occurred in the current-year ring, where early-wood vessels in the outermost ring were still functional. Nevertheless, there was significant flow in the older rings of the xylem. Total water flow through the trunk was only slightly reduced when air embolisms were artificially induced in early-wood vessels, probably because there was little change in hydraulic conductance in the root-leaf sap pathway. Embolization of the current-year vessels reactivated transport in the older rings.

Approximate Model for Turbulent Stagnation Point Flow.

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

Dechant, Lawrence

2016-01-01

Here we derive an approximate turbulent self-similar model for a class of favorable pressure gradient wedge-like flows, focusing on the stagnation point limit. While the self-similar model provides a useful gross flow field estimate this approach must be combined with a near wall model is to determine skin friction and by Reynolds analogy the heat transfer coefficient. The combined approach is developed in detail for the stagnation point flow problem where turbulent skin friction and Nusselt number results are obtained. Comparison to the classical Van Driest (1958) result suggests overall reasonable agreement. Though the model is only valid near themore » stagnation region of cylinders and spheres it nonetheless provides a reasonable model for overall cylinder and sphere heat transfer. The enhancement effect of free stream turbulence upon the laminar flow is used to derive a similar expression which is valid for turbulent flow. Examination of free stream enhanced laminar flow suggests that the rather than enhancement of a laminar flow behavior free stream disturbance results in early transition to turbulent stagnation point behavior. Excellent agreement is shown between enhanced laminar flow and turbulent flow behavior for high levels, e.g. 5% of free stream turbulence. Finally the blunt body turbulent stagnation results are shown to provide realistic heat transfer results for turbulent jet impingement problems.« less

Magnetized, mass-loaded, rotating accretion flows

NASA Astrophysics Data System (ADS)

Toniazzo, T.; Hartquist, T. W.; Durisen, R. H.

2001-03-01

We present a semi-analytical investigation of a simple one-dimensional, steady-state model for a mass-loaded, rotating, magnetized, hydrodynamical flow. Our approach is analogous to one used in early studies of magnetized winds. The model represents the infall towards a central point mass of the gas generated in a cluster of stars surrounding it, as is likely to occur in some active nuclei and starburst galaxies. We describe the properties of the different classes of infall solutions. We find that the flow becomes faster than the fast-mode speed, and hence decoupled from the centre, only for a limited range of parameter values, and when magnetic stresses are ineffective. Such flow is slowed as it approaches a centrifugal barrier, implying the existence of an accretion disc. When the flow does not become super-fast and the magnetic torque is insufficient, no steady solution extending inward to the centre exists. Finally, with a larger magnetic torque, solutions representing steady sub-Alfvénic flows are found, which can resemble spherical hydrodynamical infall. Such solutions, if applicable, would imply that rotation is not important and that any accretion disc formed would be of very limited size.

An early warning indicator for atmospheric blocking events using transfer operators

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

Tantet, Alexis, E-mail: a.j.j.tantet@uu.nl; Burgt, Fiona R. van der; Dijkstra, Henk A.

The existence of persistent midlatitude atmospheric flow regimes with time-scales larger than 5–10 days and indications of preferred transitions between them motivates to develop early warning indicators for such regime transitions. In this paper, we use a hemispheric barotropic model together with estimates of transfer operators on a reduced phase space to develop an early warning indicator of the zonal to blocked flow transition in this model. It is shown that the spectrum of the transfer operators can be used to study the slow dynamics of the flow as well as the non-Markovian character of the reduction. The slowest motionsmore » are thereby found to have time scales of three to six weeks and to be associated with meta-stable regimes (and their transitions) which can be detected as almost-invariant sets of the transfer operator. From the energy budget of the model, we are able to explain the meta-stability of the regimes and the existence of preferred transition paths. Even though the model is highly simplified, the skill of the early warning indicator is promising, suggesting that the transfer operator approach can be used in parallel to an operational deterministic model for stochastic prediction or to assess forecast uncertainty.« less

Numerical study on flow over stepped spillway using Lagrangian method

NASA Astrophysics Data System (ADS)

Wang, Junmin; Fu, Lei; Xu, Haibo; Jin, Yeechung

2018-02-01

Flow over stepped spillway has been studied for centuries, due to its unstable and the characteristics of cavity, the simulation of this type of spillway flow is always difficult. Most of the early studies of flow over stepped spillway are based on experiment, while in the recent decades, numerical studies of flow over stepped spillway draw most of the researchers’ attentions due to its simplicity and efficiency. In this study, a new Lagrangian based particle method is introduced to reproduce the phenomenon of flow over stepped spillway, the inherent advantages of this particle based method provide a convincing free surface and velocity profiles compared with previous experimental data. The capacity of this new method is proved and it is anticipated to be an alternative tool of traditional mesh based method in environmental engineering field such as the simulation of flow over stepped spillway.

Flow reconstructions in the Upper Missouri River Basin using riparian tree rings

NASA Astrophysics Data System (ADS)

Schook, Derek M.; Friedman, Jonathan M.; Rathburn, Sara L.

2016-10-01

River flow reconstructions are typically developed using tree rings from montane conifers that cannot reflect flow regulation or hydrologic inputs from the lower portions of a watershed. Incorporating lowland riparian trees may improve the accuracy of flow reconstructions when these trees are physically linked to the alluvial water table. We used riparian plains cottonwoods (Populus deltoides ssp. monilifera) to reconstruct discharge for three neighboring rivers in the Upper Missouri River Basin: the Yellowstone (n = 389 tree cores), Powder (n = 408), and Little Missouri Rivers (n = 643). We used the Regional Curve Standardization approach to reconstruct log-transformed discharge over the 4 months in early summer that most highly correlated to tree ring growth. The reconstructions explained at least 57% of the variance in historical discharge and extended back to 1742, 1729, and 1643. These are the first flow reconstructions for the Lower Yellowstone and Powder Rivers, and they are the furthest downstream among Rocky Mountain rivers in the Missouri River Basin. Although mostly free-flowing, the Yellowstone and Powder Rivers experienced a shift from early-summer to late-summer flows within the last century. This shift is concurrent with increasing irrigation and reservoir storage, and it corresponds to decreased cottonwood growth. Low-frequency flow patterns revealed wet conditions from 1870 to 1980, a period that includes the majority of the historical record. The 1816-1823 and 1861-1865 droughts were more severe than any recorded, revealing that drought risks are underestimated when using the instrumental record alone.

Comparison of Effects of Low-Flow Sevoflurane and Low-Flow Desflurane Anaesthesia on Renal Functions Using Cystatin C

PubMed Central

Duymaz, Gökçen; Yağar, Seyhan; Özgök, Ayşegül

2017-01-01

Objective Numerous studies have indicated nephrotoxic effects of sevoflurane because of its two bioproducts compound A and fluoride. Cystatin C (CyC) is a more sensitive biomarker than creatinine to show early and mild changes in kidney function. We designed this prospective randomised study to compare the effects of low-flow sevoflurane anaesthesia and low-flow desflurane anaesthesia on renal functions based on CyC levels. No studies have evaluated the effects of low-flow sevoflurane anaesthesia on renal functions based on CyC levels to date. Methods Thirty American Society of Anesthesiologists (ASA) physical status I–II patients who were scheduled for urological procedures were enrolled in this study. The patients were randomly assigned to 2 groups: low-flow sevoflurane anaesthesia or low-flow desflurane anaesthesia. Serum urea, creatinine and CyC levels were measured before the operation, just before extubation and 24 h after the operation. Creatinine clearance was calculated in the first 24-h urine sample. Results There were no significant differences in serum urea, creatinine and CyC levels or 24 h creatinine clearance between the groups. Conclusion Our study demonstrates with a more sensitive biomarker, CyC, that low-flow sevoflurane anaesthesia is safe in terms of the effects on renal function. PMID:28439441

Towards enhancing and delaying disturbances in free shear flows

NASA Technical Reports Server (NTRS)

Criminale, W. O.; Jackson, T. L.; Lasseigne, D. G.

1994-01-01

The family of shear flows comprising the jet, wake, and the mixing layer are subjected to perturbations in an inviscid incompressible fluid. By modeling the basic mean flows as parallel with piecewise linear variations for the velocities, complete and general solutions to the linearized equations of motion can be obtained in closed form as functions of all space variables and time when posed as an initial value problem. The results show that there is a continuous as well as the discrete spectrum that is more familiar in stability theory and therefore there can be both algebraic and exponential growth of disturbances in time. These bases make it feasible to consider control of such flows. To this end, the possibility of enhancing the disturbances in the mixing layer and delaying the onset in the jet and wake is investigated. It is found that growth of perturbations can be delayed to a considerable degree for the jet and the wake but, by comparison, cannot be enhanced in the mixing layer. By using moving coordinates, a method for demonstrating the predominant early and long time behavior of disturbances in these flows is given for continuous velocity profiles. It is shown that the early time transients are always algebraic whereas the asymptotic limit is that of an exponential normal mode. Numerical treatment of the new governing equations confirm the conclusions reached by use of the piecewise linear basic models. Although not pursued here, feedback mechanisms designed for control of the flow could be devised using the results of this work.

Relationship of neonatal cerebral blood flow velocity asymmetry with early motor, cognitive and language development in term infants.

PubMed

Wu, Ying-Chin; Hsieh, Wu-Shiun; Hsu, Chyong-Hsin; Chiu, Nan-Chang; Chou, Hung-Chieh; Chen, Chien-Yi; Peng, Shinn-Forng; Hung, Han-Yang; Chang, Jui-Hsing; Chen, Wei J; Jeng, Suh-Fang

2013-05-01

The objective of this study was to examine the relationships of Doppler cerebral blood flow velocity (CBFV) asymmetry measures with developmental outcomes in term infants. Doppler CBFV parameters (peak systolic velocity [PSV] and mean velocity [MV]) of the bilateral middle cerebral arteries of 52 healthy term infants were prospectively examined on postnatal days 1-5, and then their motor, cognitive and language development was evaluated with the Bayley Scales of Infant and Toddler Development, Third Edition, at 6, 12, 18 and 24 months of age. The left CBFV asymmetry measure (PSV or MV) was calculated by subtracting the right-side value from the left-side value. Left CBFV asymmetry measures were significantly positively related to motor scores at 6 (r = 0.3-0.32, p < 0.05) and 12 (r = 0.35, p < 0.05) months of age, but were not related to cognitive or language outcome. Thus, the leftward hemodynamic status of the middle cerebral arteries, as measured by cranial Doppler ultrasound in the neonatal period, predicts early motor outcome in term infants. Copyright © 2013 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

Ion flow ripples in the Earth's plasma sheet

NASA Astrophysics Data System (ADS)

De Spiegeleer, Alexandre; Hamrin, Maria; Pitkänen, Timo; Norqvist, Patrik; Mann, Ingrid

2016-04-01

For a long time, magnetotail flows were considered rather smooth and laminar, and primarily dominated by a simple convection flow pattern. However, in the early 90's, high speed bursty bulk flows (BBFs) were discovered and found to commonly perturb the underlying convection flows. In addition, there are other disturbances complicating the magnetotail flow pattern. Instabilities such as the Kelvin-Helmholz instability and the kink instability can cause different types of magnetic field oscillations, such as field line resonances. It is expected that ions will follow these oscillations if the typical time and length scales are larger than the gyroperiod and gyroradius of the ions. Though low-velocity sloshing and ripple disturbances of the average magnetotail convection flows have been observed, their connection with magnetic field oscillations is not fully understood. Furthermore, when studying BFFs, these "Ion Flow Ripples" (IFRs) are often neglected, dismissed as noise or can even erroneously be identified as BBFs. It is therefore of utter importance to find out and understand the role of IFRs in magnetotail dynamics. In a statistical investigation, we use several years of Cluster plasma sheet data to study the low-speed flows in the magnetotail. We investigate different types of IFRs, study their occurrence, and discuss their possible causes.

Non-Darcian flow to a partially penetrating well in a confined aquifer

NASA Astrophysics Data System (ADS)

Wen, Z.; Liu, K.; Chen, X.

2014-12-01

In this study, non-Darcian flow to a partially penetrating well in a confined aquifer was investigated. The flow in the horizontal direction was assumed to be non-Darcian, while the flow in the vertical direction was assumed to be Darcian. The Izbash equation was employed to describe the non-Darcian flow in the horizontal direction of the aquifer. We used a linearization procedure to approximate the non-linear term in the governing equation enabling the mathematical model to be solved using a combination of Laplace and Fourier cosine transforms. Approximate analytical solutions for the drawdown were obtained and the impacts of different parameters on the drawdown were analyzed. The results indicated that a larger power index n in the Izbash equation leads to a larger drawdown at early times, while a larger n results in a smaller drawdown at late times. The drawdowns along the vertical direction z are symmetric if the well screen is located in the center of the aquifer, and the drawdown at the center of the aquifer is the largest along the vertical direction for this case. The length of the well screen w has little impact on the drawdown at early times, while a larger length of the well screen results in a smaller drawdown at late times. The drawdown increases with Kr at early times, while it decreases as Kr increases at late times, in which Kr is the apparent radial hydraulic conductivity. A sensitivity analysis of the parameters, i.e., the specific storage Ss, w, n and Kr, indicated that the drawdown is not sensitive to them at early times, while it is very sensitive to these parameters at late times especially to the power index n.

Nandrolone and resistance training induce heart remodeling: role of fetal genes and implications for cardiac pathophysiology.

PubMed

Tanno, Ana Paula; das Neves, Vander José; Rosa, Kaleizu Teodoro; Cunha, Tatiana Sousa; Giordano, Fernanda Cristina Linarello; Calil, Caroline Morini; Guzzoni, Vinicius; Fernandes, Tiago; de Oliveira, Edilamar Menezes; Novaes, Pedro Duarte; Irigoyen, Maria Cláudia; Moura, Maria José Costa Sampaio; Marcondes, Fernanda Klein

2011-10-24

This study was conducted to assess the isolated and combined effects of nandrolone and resistance training on cardiac morphology, function, and mRNA expression of pathological cardiac hypertrophy markers. Wistar rats were randomly divided into four groups and submitted to 6 weeks of treatment with nandrolone and/or resistance training. Cardiac parameters were determined by echocardiography. Heart was analyzed for collagen infiltration. Real-time RT-PCR was used to assess the pathological cardiac hypertrophy markers. Both resistance training and nandrolone induced cardiac hypertrophy. Nandrolone increased the cardiac collagen content, and reduced the cardiac index in non-trained and trained groups, when compared with the respective vehicle-treated groups. Nandrolone reduced the ratio of maximum early to late transmitral flow velocity in non-trained and trained groups, when compared with the respective vehicle-treated groups. Nandrolone reduced the alpha-myosin heavy chain gene expression in both non-trained and trained groups, when compared with the respective vehicle-treated groups. Training reduced the beta-myosin heavy chain gene expression in the groups treated with vehicle and nandrolone. Only the association between training and nandrolone increased the expression of the skeletal alpha-actin gene and atrial natriuretic peptide in the left ventricle. This study indicated that nandrolone, whether associated with resistance training or not, induces cardiac hypertrophy, which is associated with enhanced collagen content, re-expression of fetal genes the in left ventricle, and impaired diastolic and systolic function. Copyright © 2011 Elsevier Inc. All rights reserved.

Coherent structures and flow topology of transitional separated-reattached flow over two and three dimensional geometrical shapes

NASA Astrophysics Data System (ADS)

Diabil, Hayder Azeez; Li, Xin Kai; Abdalla, Ibrahim Elrayah

2017-09-01

Large-scale organized motions (commonly referred to coherent structures) and flow topology of a transitional separated-reattached flow have been visualised and investigated using flow visualisation techniques. Two geometrical shapes including two-dimensional flat plate with rectangular leading edge and three-dimensional square cylinder are chosen to shed a light on the flow topology and present coherent structures of the flow over these shapes. For both geometries and in the early stage of the transition, two-dimensional Kelvin-Helmholtz rolls are formed downstream of the leading edge. They are observed to be twisting around the square cylinder while they stay flat in the case of the two-dimensional flat plate. For both geometrical shapes, the two-dimensional Kelvin-Helmholtz rolls move downstream of the leading edge and they are subjected to distortion to form three-dimensional hairpin structures. The flow topology in the flat plate is different from that in the square cylinder. For the flat plate, there is a merging process by a pairing of the Kelvin-Helmholtz rolls to form a large structure that breaks down directly into many hairpin structures. For the squire cylinder case, the Kelvin-Helmholtz roll evolves topologically to form a hairpin structure. In the squire cylinder case, the reattachment length is much shorter and a forming of the three-dimensional structures is closer to the leading edge than that in the flat plate case.

Hospitalist and Internal Medicine Leaders' Perspectives of Early Discharge Challenges at Academic Medical Centers.

PubMed

Patel, Hemali; Fang, Margaret C; Mourad, Michelle; Green, Adrienne; Wachter, Robert M; Murphy, Ryan D; Harrison, James D

2018-06-01

Improving early discharges may improve patient flow and increase hospital capacity. We conducted a national survey of academic medical centers addressing the prevalence, importance, and effectiveness of early-discharge initiatives. We assembled a list of hospitalist and general internal medicine leaders at 115 US-based academic medical centers. We emailed each institutional representative a 30-item online survey regarding early-discharge initiatives. The survey included questions on discharge prioritization, the prevalence and effectiveness of early-discharge initiatives, and barriers to implementation. We received 61 responses from 115 institutions (53% response rate). Forty-seven (77%) "strongly agreed" or "agreed" that early discharge was a priority. "Discharge by noon" was the most cited goal (n = 23; 38%) followed by "no set time but overall goal for improvement" (n = 13; 21%). The majority of respondents reported early discharge as more important than obtaining translators for non-English-speaking patients and equally important as reducing 30-day readmissions and improving patient satisfaction. The most commonly reported factors delaying discharge were availability of postacute care beds (n = 48; 79%) and patient-related transport complications (n = 44; 72%). The most effective early discharge initiatives reported involved changes to the rounding process, such as preemptive identification and early preparation of discharge paperwork (n = 34; 56%) and communication with patients about anticipated discharge (n = 29; 48%). There is a strong interest in increasing early discharges in an effort to improve hospital throughput and patient flow. © 2017 Society of Hospital Medicine.

Dual permeability flow behavior for modeling horizontal well production in fractured-vuggy carbonate reservoirs

NASA Astrophysics Data System (ADS)

Guo, Jian-Chun; Nie, Ren-Shi; Jia, Yong-Lu

2012-09-01

SummaryFractured-vuggy carbonate reservoirs are composed of by matrix, fracture, and vug systems. This paper is the first investigation into the dual permeability flow issue for horizontal well production in a fractured-vuggy carbonate reservoir. Considering dispersed vugs in carbonate reservoirs and treating media directly connected with horizontal wellbore as the matrix and fracture systems, a test analysis model of a horizontal well was created, and triple porosity and dual permeability flow behavior were modeled. Standard log-log type curves were drawn up by numerical simulation and flow behavior characteristics were thoroughly analyzed. Numerical simulations showed that type curves are dominated by external boundary conditions as well as the permeability ratio of the fracture system to the sum of fracture and matrix systems. The parameter κ is only relevant to the dual permeability model, and if κ is one, then the dual permeability model is equivalent to the single permeability model. There are seven main flow regimes with constant rate of horizontal well production and five flow regimes with constant wellbore pressure of horizontal well production; different flow regimes have different flow behavior characteristics. Early radial flow and linear flow regimes are typical characteristics of horizontal well production; duration of early radial flow regime is usually short because formation thickness is generally less than 100 m. Derivative curves are W-shaped, which is a reflection of inter-porosity flows between matrix, fracture, and vug systems. A distorted W-shape, which could be produced in certain situations, such as one involving an erroneously low time of inter-porosity flows, would handicap the recognition of a linear flow regime. A real case application was successfully implemented, and some useful reservoir parameters (e.g., permeability and inter-porosity flow factor) were obtained from well testing interpretation.

Debris-flow mobilization from landslides

USGS Publications Warehouse

Iverson, R.M.; Reid, M.E.; LaHusen, R.G.

1997-01-01

Field observations, laboratory experiments, and theoretical analyses indicate that landslides mobilize to form debris flows by three processes: (a) widespread Coulomb failure within a sloping soil, rock, or sediment mass, (b) partial or complete liquefaction of the mass by high pore-fluid pressures, and (c) conversion of landslide translational energy to internal vibrational energy (i.e. granular temperature). These processes can operate independently, but in many circumstances they appear to operate simultaneously and synergistically. Early work on debris-flow mobilization described a similar interplay of processes but relied on mechanical models in which debris behavior was assumed to be fixed and governed by a Bingham or Bagnold rheology. In contrast, this review emphasizes models in which debris behavior evolves in response to changing pore pressures and granular temperatures. One-dimensional infinite-slope models provide insight by quantifying how pore pressures and granular temperatures can influence the transition from Coulomb failure to liquefaction. Analyses of multidimensional experiments reveal complications ignored in one-dimensional models and demonstrate that debris-flow mobilization may occur by at least two distinct modes in the field.

Validation of thermal techniques for measurement of pelvic organ blood flows in the nonpregnant sheep: comparison with transit-time ultrasonic and microsphere measurements of blood flow

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

Randall, N.J.; Beard, R.W.; Sutherland, I.A.

1988-03-01

Data obtained from a thermal system capable of measuring changes in organ temperature as well as tissue thermal clearance in the uterus and vagina have been compared with blood flow measured continuously with a transit-time ultrasound volume-flow sensor placed around the common internal iliac artery and intermittently with radioactive microspheres in the chronically instrumented nonpregnant sheep. Temperature changes in both the uterus and the vagina correlated well with blood flow changes measured by both techniques after intravenous administration of estradiol or norepinephrine. Thermal clearance did not correlate well with blood flow in the vagina or uterus. These methods may havemore » value in the investigation of blood flow patterns in various clinical situations such as the pelvic pain syndrome and early pregnancy.« less

Multistream hydrodynamic modeling of interhemispheric plasma flow

NASA Technical Reports Server (NTRS)

Rasmussen, C. E.; Schunk, R. W.

1988-01-01

Interhemispheric plasma flow was simulated using one-stream and two-stream hydrodymic models in order to test the suggestion of Banks et al. (1971) and others that the collision of high-speed flows originating from the conjugate hemispheres will cause the formation of a pair of shocks. The single-fluid hydrodynamic equations were modified to include multiple ion streams, allowing for the possibility of counterstreaming flow. It was found that a counterstreaming of ion streams from conjugate hemispheres does occur during the early stages of the refilling of plamaspheric flux tubes, and that a pair of reverse shocks does form. These shocks form away from the equator, and their subsequent motion creates conditions similar to those predicted by the single-stream hydrodynamic models. The findings support the conclusion of earlier studies that the refilling of the plasmasphere occurs from the equatorial region downward.

Changes in flow in the Beaver-North Canadian River basin upstream from Canton Lake, western Oklahoma

USGS Publications Warehouse

Wahl, Kenneth L.; Tortorelli, Robert L.

1997-01-01

This report presents the results of an evaluation of hydrologic data for the Beaver-North Canadian River basin upstream from Canton Lake in western Oklahoma. It examines the climatic and hydrologic data for evidence of trends. The hydrologic data examined includes total annual flow, base flow, and annual peak discharges. This study was conducted to determine if there is evidence of trends present in hydrologic and climatic data. All available streamflow-gaging station data, with at least 10 or more years of record, were examined for trends. In addition, the data were divided into an 'early' period (ending in 1971), representing conditions before ground-water levels had declined appreciably, and a 'recent' period (1978-1994), reflecting the condition of declining ground-water levels, including the effects of storage reservoirs. Tests for trend, moving averages, and comparisons of median and average flows for an early period (ending in 1971) with those for the recent period (1978-1994) show that the total annual volume of flow and the magnitudes of instantaneous annual peak discharges measured at most gaging stations in the Beaver- North Canadian River basin have decreased in recent years. Precipitation records for the panhandle, however, show no corresponding changes. The changes in flow are most pronounced in the headwaters upstream from Woodward, but also are evident at Woodward and near Seiling, which represents the inflow to Canton Lake. The average annual discharge decreased between the early period and the recent period by the following amounts: near Guymon, 18,000 acre-feet; at Beaver, 68,000 acre-feet; at Woodward, 72,000 acre-feet; and near Seiling, 63,000 acre-feet. These decreases, expressed as a percentage of the average flows for the early period, were 91 percent near Guymon, 82 percent at Beaver, 49 percent at Woodward, and 37 percent near Seiling. The medians of the annual peak discharges decreased from the early period to the recent period by the

α-, β-phenomena in the post-symmetry break for the flow past a circular cylinder

NASA Astrophysics Data System (ADS)

Kalita, Jiten C.; Sen, Shuvam

2017-03-01

In the existing literature, the so-called α- and β-phenomena have been reported only for the early stages for the flow past an impulsively started circular cylinder. The current study endeavours to explore the possible existence of these phenomena even in the later stages of the flow. The flow is computed using a recently developed compact finite difference method for the biharmonic form of the two-dimensional Navier-Stokes equations for a wide range of Reynolds numbers (Re). We establish that these secondary phenomena not only appear once the wake becomes asymmetric but also periodically during the post-vortex shedding period for Re = 1000. Further, the recently reported sub-α- and sub-β-phenomena for Re = 5000 at the tertiary level during the early stages of the flow could be identified even during the later stages of the flow as well. The formation of these tertiary structures has been explained through a detailed theoretical characterization of the topological aspects of the boundary layer separation. Both qualitative and quantitative results are provided to substantiate our claim.

The Detection of Water Flow in Rectangular Microchannels by Terahertz Time Domain Spectroscopy

PubMed Central

Song, Yan; Zhao, Kun; Zuo, Jian; Wang, Cuicui; Li, Yizhang; Miao, Xinyang; Zhao, Xiaojing

2017-01-01

Flow characteristics of water were tested in a rectangular microchannel for Reynolds number (Re) between 0 and 446 by terahertz time domain spectroscopy (THz-TDS). Output THz peak trough intensities and the calculated absorbances of the flow were analyzed theoretically. The results show a rapid change for Re < 250 and a slow change as Re increases, which is caused by the early transition from laminar to transition flow beginning nearly at Re = 250. Then this finding is confirmed in the plot of the flow resistant. Our results demonstrate that the THz-TDS could be a valuable tool to monitor and character the flow performance in microscale structures. PMID:29027922

Effect of childhood malnutrition on salivary flow and pH.

PubMed

Psoter, Walter J; Spielman, Andrew L; Gebrian, Bette; St Jean, Rudolph; Katz, Ralph V

2008-03-01

While protein-energy malnutrition may have multiple effects on oral tissues and subsequent disease development, reports of the effect of malnutrition on the human salivary glands are sparse. A retrospective cohort study of the effect of early childhood protein-energy malnutrition (EC-PEM) and adolescent nutritional status on salivary flow and pH was conducted with rural Haitian children, ages 11-19 years (n=1017). Malnutrition strata exposure cohorts were based on 1988-1996 weight-for-age records which covered the birth through 5-year-old period for all subjects. Then, data on current anthropometrical defined nutritional status categories, stimulated and unstimulated salivary flow rates, and salivary pH were collected for the same subjects of 11-19 years old during field examinations in the summer of 2005. Multivariate analysis of variance (MANOVA) was used for the analyses. Stimulated and unstimulated salivary flow rates were reduced at statistically significant levels in subjects who had experienced severe malnutrition in their early childhood or who had continuing nutrition stress which resulted in delayed growth, as measured at ages 11-19 years. Salivary pH demonstrated little clinically meaningful variability between malnourished and nonmalnourished groups. This study is the first to report of a continuing effect on diminished salivary gland function into adolescence as a result of early childhood malnutrition (EC-PEM) and suggests that exocrine glandular systems may be compromised for extended periods following EC-PEM, which may have important implications for the body's systemic antimicrobial defences.

Storm flow export of metolachlor from a coastal plain watershed.

PubMed

Watts, D W; Novak, J M; Johnson, M H; Stone, K C

2000-03-01

During an 18-month (1994-1995) survey of the surface water in an Atlantic Coastal Plain watershed, metolachlor was most frequently detected during storm flow events. Therefore, a sampling procedure, focused on storm flow, was implemented in June of 1996. During 1996, three tropical cyclones made landfall within 150 km of the watershed. These storms, as well as several summer thunderstorms, produced six distinct storm flow events within the watershed. Metolachlor was detected leaving the watershed during each event. In early September, Hurricane Fran produced the largest storm flow event and accounted for the majority of the metolachlor exports. During the storm event triggered by Hurricane Fran, the highest daily average flow (7.5 m2 s-1) and highest concentration (5.1 micrograms L-1) ever measured at the watershed outlet were recorded. Storm flow exports leaving the watershed represented 0.1 g ha-1 or about 0.04% of active ingredient applied.

Flow-separation patterns on symmetric forebodies

NASA Technical Reports Server (NTRS)

Keener, Earl R.

1986-01-01

Flow-visualization studies of ogival, parabolic, and conical forebodies were made in a comprehensive investigation of the various types of flow patterns. Schlieren, vapor-screen, oil-flow, and sublimation flow-visualization tests were conducted over an angle-of-attack range from 0 deg. to 88 deg., over a Reynolds-number range from 0.3X10(6) to 2.0X10(6) (based on base diameter), and over a Mach number range from 0.1 to 2. The principal effects of angle of attack, Reynolds number, and Mach number on the occurrence of vortices, the position of vortex shedding, the principal surface-flow-separation patterns, the magnitude of surface-flow angles, and the extent of laminar and turbulent flow for symmetric, asymmetric, and wake-like flow-separation regimes are presented. It was found that the two-dimensional cylinder analogy was helpful in a qualitative sense in analyzing both the surface-flow patterns and the external flow field. The oil-flow studies showed three types of primary separation patterns at the higher Reynolds numbers owing to the influence of boundary-layer transition. The effect of angle of attack and Reynolds number is to change the axial location of the onset and extent of the primary transitional and turbulent separation regions. Crossflow inflectional-instability vortices were observed on the windward surface at angles of attack from 5 deg. to 55 deg. Their effect is to promote early transition. At low angles of attack, near 10 deg., an unexpected laminar-separation bubble occurs over the forward half of the forebody. At high angles of attack, at which vortex asymmetry occurs, the results support the proposition that the principal cause of vortex asymmetry is the hydrodynamic instability of the inviscid flow field. On the other hand, boundary-layer asymmetries also occur, especially at transitional Reynolds numbers. The position of asymmetric vortex shedding moves forward with increasing angle of attack and with increasing Reynolds number, and moves

Flow reconstructions in the Upper Missouri River Basin using riparian tree rings

USGS Publications Warehouse

Schook, Derek M.; Friedman, Jonathan M.; Rathburn, Sara L.

2016-01-01

River flow reconstructions are typically developed using tree rings from montane conifers that cannot reflect flow regulation or hydrologic inputs from the lower portions of a watershed. Incorporating lowland riparian trees may improve the accuracy of flow reconstructions when these trees are physically linked to the alluvial water table. We used riparian plains cottonwoods (Populus deltoides ssp. monilifera) to reconstruct discharge for three neighboring rivers in the Upper Missouri River Basin: the Yellowstone (n = 389 tree cores), Powder (n = 408), and Little Missouri Rivers (n = 643). We used the Regional Curve Standardization approach to reconstruct log-transformed discharge over the 4 months in early summer that most highly correlated to tree ring growth. The reconstructions explained at least 57% of the variance in historical discharge and extended back to 1742, 1729, and 1643. These are the first flow reconstructions for the Lower Yellowstone and Powder Rivers, and they are the furthest downstream among Rocky Mountain rivers in the Missouri River Basin. Although mostly free-flowing, the Yellowstone and Powder Rivers experienced a shift from early-summer to late-summer flows within the last century. This shift is concurrent with increasing irrigation and reservoir storage, and it corresponds to decreased cottonwood growth. Low-frequency flow patterns revealed wet conditions from 1870 to 1980, a period that includes the majority of the historical record. The 1816–1823 and 1861–1865 droughts were more severe than any recorded, revealing that drought risks are underestimated when using the instrumental record alone.

Changes in erosional style on early Mars - External versus internal influences

NASA Technical Reports Server (NTRS)

Postawko, Susan E.; Fanale, Fraser P.

1993-01-01

A quantitative relationship is derived between the effectiveness of an atmospheric greenhouse and that of internal heat flow in producing the morphological differences between early and later Martian terrains. The derived relationship is used for two purposes: (1) to evaluate the relative importance of the atmospheric CO2 greenhouse effect and the internal regolith thermal gradient in producing morphological changes for any value of the heat flow (and conductivity values); and (2) to assess the absolute importance of each for specific values of the heat flow which are thought to be reasonable on independent geophysical grounds.

Transmitral flow velocity-contour variation after premature ventricular contractions: a novel test of the load-independent index of diastolic filling.

PubMed

Boskovski, Marko T; Shmuylovich, Leonid; Kovács, Sándor J

2008-12-01

The new echocardiography-based, load-independent index of diastolic filling (LIIDF) M was assessed using load-/shape-varying E-waves after premature ventricular contractions (PVCs). Twenty-six PVCs in 15 subjects from a preexisting simultaneous echocardiography-catheterization database were selected. Perturbed load-state beats, defined as the first two post-PVC E-waves, and steady-state E-waves, were subjected to conventional and model-based analysis. M, a dimensionless index, defined by the slope of the peak driving-force vs. peak (filling-opposing) resistive-force regression, was determined from steady-state E-waves alone, and from load-perturbed E-waves combined with a matched number of subsequent beats. Despite high degrees of E-wave shape variation, M derived from load-varying, perturbed beats and M derived from steady-state beats alone were indistinguishable. Because the peak driving-force vs. peak resistive-force relation determining M remains highly linear in the extended E-wave shape and load variation regime observed, we conclude that M is a robust LIIDF.

Prevalence of E/A wave fusion and A wave truncation in DDD pacemaker patients with complete AV block under nominal AV intervals.

PubMed

Poller, Wolfram C; Dreger, Henryk; Schwerg, Marius; Melzer, Christoph

2015-01-01

Optimization of the AV-interval (AVI) in DDD pacemakers improves cardiac hemodynamics and reduces pacemaker syndromes. Manual optimization is typically not performed in clinical routine. In the present study we analyze the prevalence of E/A wave fusion and A wave truncation under resting conditions in 160 patients with complete AV block (AVB) under the pre-programmed AVI. We manually optimized sub-optimal AVI. We analyzed 160 pacemaker patients with complete AVB, both in sinus rhythm (AV-sense; n = 129) and under atrial pacing (AV-pace; n = 31). Using Doppler analyses of the transmitral inflow we classified the nominal AVI as: a) normal, b) too long (E/A wave fusion) or c) too short (A wave truncation). In patients with a sub-optimal AVI, we performed manual optimization according to the recommendations of the American Society of Echocardiography. All AVB patients with atrial pacing exhibited a normal transmitral inflow under the nominal AV-pace intervals (100%). In contrast, 25 AVB patients in sinus rhythm showed E/A wave fusion under the pre-programmed AV-sense intervals (19.4%; 95% confidence interval (CI): 12.6-26.2%). A wave truncations were not observed in any patient. All patients with a complete E/A wave fusion achieved a normal transmitral inflow after AV-sense interval reduction (mean optimized AVI: 79.4 ± 13.6 ms). Given the rate of 19.4% (CI 12.6-26.2%) of patients with a too long nominal AV-sense interval, automatic algorithms may prove useful in improving cardiac hemodynamics, especially in the subgroup of atrially triggered pacemaker patients with AV node diseases.

Selected computations of transonic cavity flows

NASA Technical Reports Server (NTRS)

Atwood, Christopher A.

1993-01-01

An efficient diagonal scheme implemented in an overset mesh framework has permitted the analysis of geometrically complex cavity flows via the Reynolds averaged Navier-Stokes equations. Use of rapid hyperbolic and algebraic grid methods has allowed simple specification of critical turbulent regions with an algebraic turbulence model. Comparisons between numerical and experimental results are made in two dimensions for the following problems: a backward-facing step; a resonating cavity; and two quieted cavity configurations. In three-dimensions the flow about three early concepts of the stratospheric Observatory For Infrared Astronomy (SOFIA) are compared to wind-tunnel data. Shedding frequencies of resolved shear layer structures are compared against experiment for the quieted cavities. The results demonstrate the progress of computational assessment of configuration safety and performance.

Early Rebleeding after Brain Arteriovenous Malformation Rupture, Clinical Impact and Predictive Factors: A Monocentric Retrospective Cohort Study.

PubMed

Shotar, Eimad; Pistocchi, Silvia; Haffaf, Idriss; Bartolini, Bruno; Jacquens, Alice; Nouet, Aurélien; Chiras, Jacques; Degos, Vincent; Sourour, Nader-Antoine; Clarençon, Frédéric

2017-01-01

Brain arteriovenous malformations (BAVMs) are a leading cause of intracranial hemorrhage in young adults. This study aimed to identify individual predictive factors of early rebleeding after BAVM rupture and determine its impact on prognosis. Early rebleeding was defined as a spontaneous intracranial hemorrhage within 30 days of BAVM rupture in patients with nonobliterated BAVMs. One hundred fifty one patients with 158 BAVM hemorrhagic events admitted to a tertiary care center during 14 years were included. Univariate followed by multivariate logistic regression was performed to assess the impact of early rebleeding on in-hospital mortality and modified Rankin Scale (mRS) score beyond 3 months and to identify independent predictors of early rebleeding. Eight early rebleeding events were observed, 6 of which occurred during the first 7 days. Early rebleeding was independently and significantly associated with poor outcome (mRS ≥3 beyond 3 months, p = 0.004) but not with in-hospital mortality (p = 0.9). Distal flow-related aneurysms (p = 0.009) and altered consciousness with a Glasgow coma scale score of 3 (p = 0.01) were independently associated with early rebleeding. Early rebleeding is a severe complication that can occur after BAVM-related hemorrhage. Distal flow-related aneurysms and initial altered consciousness are associated with early rebleeding. © 2017 S. Karger AG, Basel.

Detection of early changes in lung cell cytology by flow-systems analysis techniques. [Rats

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

Steinkamp, J.A.; Wilson, J.S.; Svitra, Z.V.

1980-03-01

Ongoing experiments designed to develop automated flow-analysis methods for assaying damage to pulmonary lavage cells in experimental animals exposed by inhalation to environmental pollutants are summarized. Pulmonary macrophages were characterized on their ability to phagocytize polystyrene latex fluorescent spheres. Lung cells consisting primarily of macrophages and leukocytes were analyzed for fluorescence (phagocytosis of spheres) and size using flow cytometric methods. Studies also concentrated on combining phagocytosis with other cellular parameters (DNA content, cell viability, and B-glucuronidase activity). As baseline studies are completed in normal animals, experimental animals will be exposed to gaseous and particulate environmental pollutants. (ERB

Effect of Unsaturated Flow on Delayed Response of Unconfined Aquifiers to Pumping

NASA Astrophysics Data System (ADS)

Tartakovsky, G.; Neuman, S. P.

2005-12-01

A new analytical solution is presented for the delayed response process characterizing flow to a partially penetrating well in an unconfined aquifer. The new solution generalizes that of Neuman [1972, 1974] by accounting for unsaturated flow above the water table. Axially symmetric three-dimensional flow in the unsaturated zone is described by a linearized version of Richards' equation in which hydraulic conductivity and water content vary exponentially with incremental capillary pressure head relative to its air entry value (defining the interface between the saturated and unsaturated zones). Unsaturated soil properties are characterized by an exponent κ having the dimension of inverse length and a dimensionless exponent κD = κb where b is initial saturated thickness. Our treatment of the unsaturated zone is similar to that of Kroszynski and Dagan [1975] who however have ignored internal (artesian) aquifer storage. It has been suggested by Boulton [1954, 1963, 1970] and Neuman [1972, 1974], and is confirmed by our solution, that internal storage is required to reproduce the early increase in drawdown characterizing delayed response to pumping in typical aquifers. According to our new solution such aquifers are characterized by relatively large κ_ D values, typically 10 or larger; in the limit as κD tends to infinity (the soil unsaturated water retention capacity becomes insignificant and/or aquifer thickness become large), unsaturated flow becomes unimportant and our solution reduces to that of Neuman. In typical cases corresponding to κD larger than or equal to 10, unsaturated flow is found to have little impact on early and late dimensionless time behaviors of drawdown measured wholly or in part at some distance below the water table; unsaturated flow causes drawdown to increase slightly at intermediate dimensionless time values that represent transition from an early artesian dominated to a late water-table dominated flow regime. The increase in drawdown

SDOCT Doppler velocimetry for investigating the morphological influences on blood flow in the developing chick embryo heart

NASA Astrophysics Data System (ADS)

Davis, Anjul M.; Rothenberg, Florence G.; Law, Tzuo H.; Taber, Larry A.; Izatt, Joseph A.

2007-02-01

The onset of congenital heart disease (CHD) is believed to occur at very early stages of development. Investigations in the initiation and development of CHD has been hampered by the inability to image early stage heart structure and function, in vivo. Imaging small animals using optical coherence tomography (OCT) has filled a niche between the limited penetration depth of confocal microscopy and insufficient resolution from ultrasound. Previous demonstrations of chick heart imaging using OCT have entailed excision of, or arresting the heart to prevent motion artifacts. In this summary, we introduce SDOCT Doppler velocimetry as an enhancement of Doppler OCT for in vivo measurement of localized temporal blood flow dynamics. With this technique, dynamic velocity waveforms were measured in the outflow tract of the heart tube. These flow dynamics correlate to a finite element model of pulsatile flow and may lead to a further understanding of morphological influences on early heart development.

Becoming Professional? Exploring Early Years Professional Status and Its Implications for Workforce Reform in England

ERIC Educational Resources Information Center

Simpson, Donald

2010-01-01

Across the "European learning space" (Lawn, 2006) professionalisation of early years workforces has become a key priority and there has been a flow of this policy between borders (Oberhuemer, 2005). Early Years Professional Status (EYPS) is central to these developments in England. Within what is regarded as a traditionally…

Connectivity Reveals Sources of Predictive Coding Signals in Early Visual Cortex During Processing of Visual Optic Flow.

PubMed

Schindler, Andreas; Bartels, Andreas

2017-05-01

Superimposed on the visual feed-forward pathway, feedback connections convey higher level information to cortical areas lower in the hierarchy. A prominent framework for these connections is the theory of predictive coding where high-level areas send stimulus interpretations to lower level areas that compare them with sensory input. Along these lines, a growing body of neuroimaging studies shows that predictable stimuli lead to reduced blood oxygen level-dependent (BOLD) responses compared with matched nonpredictable counterparts, especially in early visual cortex (EVC) including areas V1-V3. The sources of these modulatory feedback signals are largely unknown. Here, we re-examined the robust finding of relative BOLD suppression in EVC evident during processing of coherent compared with random motion. Using functional connectivity analysis, we show an optic flow-dependent increase of functional connectivity between BOLD suppressed EVC and a network of visual motion areas including MST, V3A, V6, the cingulate sulcus visual area (CSv), and precuneus (Pc). Connectivity decreased between EVC and 2 areas known to encode heading direction: entorhinal cortex (EC) and retrosplenial cortex (RSC). Our results provide first evidence that BOLD suppression in EVC for predictable stimuli is indeed mediated by specific high-level areas, in accord with the theory of predictive coding. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Transient solute transport with sorption in Poiseuille flow

NASA Astrophysics Data System (ADS)

Hesse, M. A.; Zhang, L.; Wang, M.

2016-12-01

Sorption onto the wall has been observed to both increase [Lungu and Moffatt, 1982] and decrease the average solute transport velocity [Golay, 1958], relative to the mean flow velocity. Similarly, opposite conclusion have been reached for the effect of sorption on dispersion. In this work, we study transient solute transport in Poiseuille flow with sorptive boundary and initial transversely uniform distribution (linear release) to reconcile the two different views on solute transport (figure 1) with sorption. Two-dimensional simulations in figure 2 show that there is a transition from fast transport dominated by a fast-moving pulse in the middle of the channel at early times, to slow transport at late times once desorption from the walls becomes important. A set of series solutions for zeroth, first and second longitudinal moment have been derived and we show that the zeroth-order term in the solution corresponds to the slow transport in the late regime, while the first-order term corresponds to the fast transport in the early regime (figure 3). Based on the analytical solution, the time scales for early regime and late regimes of both the velocity and the dispersion coefficient have been determined for an equilibrium sorption model and a kinetic linear sorption model. Furthermore, we give approximated analytical solution when both adsorption and desorption are slow. References M.J.E. Golay. Theory of chromatography in open and coated tubular columns iwth round and rectangular cross-sections. In D.H.Desty, editor, Gas Chromatography, pages 36-53, New York, 1958. Academic Press Inc. E.M. Lungu and H.K. Moffatt. the effect of wall conductance on heat diffusion in duct flow. Journal of Engineering Mathematics, 1692 ;121-136, 1982.

Prediction of Left Ventricular Filling Pressure by 3-Dimensional Speckle-Tracking Echocardiography in Patients With Coronary Artery Disease.

PubMed

Ma, Hong; Xie, Rong-Ai; Gao, Li-Jian; Zhang, Jin-Ping; Wu, Wei-Chun; Wang, Hao

2015-10-01

The purpose of this study was to investigate the diagnostic value of 3-dimensional (3D) speckle-tracking echocardiography for estimating left ventricular filling pressure in patients with coronary artery disease (CAD) and a preserved left ventricular ejection fraction. Altogether, 84 patients with CAD and 30 age- and sex-matched healthy control participants in sinus rhythm were recruited prospectively. All participants underwent conventional and 3D speckle-tracking echocardiography. Global strain values were automatically calculated by 3D speckle-tracking analysis. The left ventricular end-diastolic pressure (LVEDP) was determined invasively by left heart catheterization. Echocardiography and cardiac catheterization were performed within 24 hours. Compared with the controls, patients with CAD showed lower global longitudinal strain, global circumferential strain, global area strain, and global radial strain. Patients with CAD who had an elevated LVEDP had much lower levels of all 4 3D-speckle-tracking echocardiographic variables. Pearson correlation analysis revealed that the LVEDP correlated positively with the early transmitral flow velocity/early diastolic myocardial velocity (E/E') ratio, global longitudinal strain, global circumferential strain, and global area strain. It correlated negatively with global radial strain. Receiver operating characteristic curve analysis revealed that these 3D speckle-tracking echocardiographic indices could effectively predict elevated left ventricular filling pressure (LVEDP >15 mm Hg) in patients with CAD (areas under the curve: global longitudinal strain, 0.78; global radial strain, 0.77; global circumferential strain, 0.75; and global area strain, 0.74). These parameters, however, showed no advantages over the commonly used E/E' ratio (area under the curve, 0.84). Three-dimensional speckle-tracking echocardiography was a practical technique for predicting elevated left ventricular filling pressure, but it might not be

Association of Central Sleep Apnea with Impaired Heart Structure and Cardiovascular Hemodynamics in Patients with Chronic Heart Failure.

PubMed

Kazimierczak, Anna; Krzesiński, Paweł; Gielerak, Grzegorz; Uziębło-Życzkowska, Beata; Smurzyński, Paweł; Ryczek, Robert; Cwetsch, Andrzej; Skrobowski, Andrzej

2016-08-25

BACKGROUND Advanced heart failure (HF) is commonly accompanied by central sleep apnea (CSA) with Cheyne-Stokes respiration (CSR). The aim of this study was to evaluate the relationship between CSA/CSR and other clinical features of HF, with particular emphasis on cardiovascular hemodynamics. MATERIAL AND METHODS In 161 stable HF patients with left ventricular ejection fraction (LVEF) ≤45% (NYHA class I-III; mean LVEF 32.8%) the clinical evaluation included: LVEF; left and right ventricular end-diastolic diameter (LVDd, RVDd); ratio of early transmitral flow velocity to early diastolic septal mitral annulus velocity (E/e') assessed by echocardiography; stroke index (SI); heart rate (HR); cardiac index (CI); and systemic vascular resistance index (SVRI) assessed by impedance cardiography (ICG). The comparison was performed between 2 subgroups: one with moderate/severe CSA/CSR - CSR_ [+] (n=51), and one with mild or no CSA/CSR - CSR_ [-] (n=110). RESULTS CSR_ [+] patients presented more advanced NYHA class (p<0.001) and more frequently had permanent atrial fibrillation (p=0.018). Moreover, they had: lower LVEF (p<0.0001); higher LVDd (p<0.0001), RVDd (p<0.001), and E/e' (p<0.001); lower SI (p<0.001) and CI (p=0.009); and higher HR (p=0.044) and SVRI (p=0.016). The following predictors of CSR_ [+] were identified: NYHA class (OR=3.34 per class, p<0.001, which was the only independent predictor); atrial fibrillation (OR=2.29, p=0.019); RV enlargement (OR=2.75, p=0.005); LVEF<35% (OR=3.38, p=0.001); E/e' (OR=3.15; p=0.003); and SI<35 ml/m2 (OR=2.96, p=0.003). CONCLUSIONS Presence of CSA/CSR in HF is associated with NYHA class, atrial fibrillation and more advanced impairment of cardiovascular structure and hemodynamics. Patient functional state remains the main determinant of CSR.

Significance of left ventricular diastolic function on outcomes after surgical ventricular restoration.

PubMed

Marui, Akira; Nishina, Takeshi; Saji, Yoshiaki; Yamazaki, Kazuhiro; Shimamoto, Takeshi; Ikeda, Tadashi; Sakata, Ryuzo

2010-05-01

Surgical ventricular restoration (SVR) has been introduced to restore the dilated left ventricular (LV) chamber and improve LV systolic function; however, SVR has also been reported to detrimentally affect LV diastolic properties. We sought to investigate the impact of preoperative LV diastolic function on outcomes after SVR in patients with heart failure. Sixty-seven patients (60 +/- 14 years) with LV systolic dysfunction (LV ejection fraction, 0.27 +/- 0.10) underwent SVR. They were evaluated by echocardiography preoperatively, and early (transmitral flow (impaired relaxation, pseudonormal, and restrictive filling patterns). Patients in the restrictive group showed far greater cardiovascular mortality than the other two groups (p < 0.0001). The multivariate analysis showed that preoperative restrictive filling pattern was a predominant predictor for adjusted cardiovascular death (p = 0.023; hazard ratio = 3.0). Left ventricular ejection fraction, LV end-diastolic volume, and grade of mitral regurgitation improved in all groups early after surgery; however, these variables in the restrictive group significantly deteriorated late after surgery (from 29 +/- 8 to 25 +/- 6 for LV ejection fraction; from 183 +/- 59 to 226 +/- 53 for left ventricular end-diastolic volume; and from 0.7 +/- 0.6 to 1.7 +/- 0.9 for mitral regurgitation grade; p < 0.05 for all). In patients with LV systolic dysfunction undergoing SVR, preoperative restrictive LV diastolic filling pattern strongly related to higher mortality with aggravation of LV systolic function, mitral regurgitation grade, or LV remodeling. This might be attributable to deterioration of diastolic function induced by SVR. Copyright (c) 2010 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

World Health Organization cardiovascular risk stratification and target organ damage.

PubMed

Piskorz, D; Bongarzoni, L; Citta, L; Citta, N; Citta, P; Keller, L; Mata, L; Tommasi, A

2016-01-01

Prediction charts allow treatment to be targeted according to simple markers of cardiovascular risk; many algorithms do not recommend screening asymptomatic target organ damage which could change dramatically the assessment. To demonstrate that target organ damage is present in low cardiovascular risk hypertensive patients and it is more frequent and severe as global cardiovascular risk increases. Consecutive hypertensive patients treated at a single Latin American center. Cardiovascular risk stratified according to 2013 WHO/ISH risk prediction chart America B. Left ventricular mass assessed by Devereux method, left ventricular hypertrophy considered >95g/m(2) in women and >115g/m(2) in men. Transmitral diastolic peak early flow velocity to average septal/lateral peak early diastolic relaxation velocity (E/e' ratio) measured cut off value >13. Systolic function assessed by tissue Doppler average interventricular septum/lateral wall mitral annulus rate systolic excursion (s wave). A total of 292 patients were included of whom 159 patients (54.5%) had cardiovascular risk of <10%, 90 (30.8%) had cardiovascular risk of 10-20% and 43 (14.7%) had cardiovascular risk of >20%. Left ventricular hypertrophy was detected in 17.6% low risk patients, 27.8% in medium risk and 23.3% in high risk (p<0.05), abnormal E/e' ratio was found in 13.8%, 31.1% and 27.9%, respectively (p<0.05). Mean s wave was 8.03+8, 8.1+9 and 8.7+1cm/s for low, intermediate and high risk patients, respectively (p<0.025). Target organ damage is more frequent and severe in high risk; one over four subjects was misclassified due to the presence of asymptomatic target organ damage. Copyright © 2015 SEHLELHA. Published by Elsevier España, S.L.U. All rights reserved.

Mechanical Power Flow Changes during Multijoint Movement Acquisition

ERIC Educational Resources Information Center

Kadota, Koji; Matsuo, Tomoyuki; Hashizume, Ken; Tezuka, Kazushi

2006-01-01

We investigated the differences in mechanical power flow in early and late practice stages during a cyclic movement consisting of upper arm circumduction to clarify the change in mechanical energy use with skill acquisition. Seven participants practiced the task every other day until their joint angular movements conformed to those of an expert.…

Flow Fields of the 3.5 Ga Komati Formation, South Africa: Geochemical, Stratigraphic, and Temporal relationships between Massive, Vesicular, and Spinifex flows

NASA Astrophysics Data System (ADS)

Dann, J. C.

2007-12-01

A challenge of Archean volcanology is to reconstruct submarine flow fields by mapping and analyzing vertically dipping sequences of lavas. Some flow fields are bound by sediments and/or seafloor alteration that mark clear gaps in volcanism. Flow fields in the Lower Komati Fm are defined by alternating layers of komatiite (26% MgO) and komatiitic basalt (15% MgO). Five komatiite flow fields (100-200m thick) repeat the same stratigraphic zoning of spinifex overlying massive komatiite, and each flow field has a distinct Al2O3/CaO, a ratio unaffected by olivine fractionation, consistent with the contention that each komatiite flow field represents a distinct batch of mantle melting. Although massive and spinifex komatiite form distinct stratigraphic units on a map scale, detailed outcrop mapping reveals that the change in flow type represents a transition within a single flow field. In one type of transition, thin massive flows alternate with spinifex flow lobes of a compound flow unit. In another, a vesicular flow along the boundary links the underlying massive komatiite and overlying spinifex flows in time. The vesicular flow has alternating spinifex and vesicular layers that form a distinctive crust above a thick massive interior. Locally, this crust is tilted, intruded by massive komatiite from the interior, and overlain by a thick breccia including a spinifex flow broken into blocks and rotated like dominoes by the tilting. These outcrop relations indicate that spinifex flow lobes were starting to flow over the vesicular flow before it had undergone differential inflation, a temporal link between the lower massive and upper spinifex komatiites consistent with their belonging to the same flow field. The transition in flow type may reflect 1) an overlap of proximal and distal facies of komatiite flows as eruption rates waned and/or 2) thermal maturation prior to eruption. Early, cooler, crystal-rich, massive lava, flowing out as thick sheet flows, was replaced by

The role of input-output analysis of energy and ecologic systems. In the early development of ecological economics--a personal perspective.

PubMed

Hannon, Bruce

2010-01-01

A summary is provided of the early history of research on the flow of nonrenewable energy resources through the economy and of the flow of renewable energy resources through a natural ecosystem. The techniques are similar, and many specific applications are provided. A combined economic and ecological technique is also defined. The early history and people of the International Society Ecological Economic are cited.

Extended flow cytometry characterization of normal bone marrow progenitor cells by simultaneous detection of aldehyde dehydrogenase and early hematopoietic antigens: implication for erythroid differentiation studies

PubMed Central

Mirabelli, Peppino; Di Noto, Rosa; Lo Pardo, Catia; Morabito, Paolo; Abate, Giovanna; Gorrese, Marisa; Raia, Maddalena; Pascariello, Caterina; Scalia, Giulia; Gemei, Marica; Mariotti, Elisabetta; Del Vecchio, Luigi

2008-01-01

Background Aldehyde dehydrogenase (ALDH) is a cytosolic enzyme highly expressed in hematopoietic precursors from cord blood and granulocyte-colony stimulating factor mobilized peripheral blood, as well as in bone marrow from patients with acute myeloblastic leukemia. As regards human normal bone marrow, detailed characterization of ALDH+ cells has been addressed by one single study (Gentry et al, 2007). The goal of our work was to provide new information about the dissection of normal bone marrow progenitor cells based upon the simultaneous detection by flow cytometry of ALDH and early hematopoietic antigens, with particular attention to the expression of ALDH on erythroid precursors. To this aim, we used three kinds of approach: i) multidimensional analytical flow cytometry, detecting ALDH and early hematopoietic antigens in normal bone marrow; ii) fluorescence activated cell sorting of distinct subpopulations of progenitor cells, followed by in vitro induction of erythroid differentiation; iii) detection of ALDH+ cellular subsets in bone marrow from pure red cell aplasia patients. Results In normal bone marrow, we identified three populations of cells, namely ALDH+CD34+, ALDH-CD34+ and ALDH+CD34- (median percentages were 0.52, 0.53 and 0.57, respectively). As compared to ALDH-CD34+ cells, ALDH+CD34+ cells expressed the phenotypic profile of primitive hematopoietic progenitor cells, with brighter expression of CD117 and CD133, accompanied by lower display of CD38 and CD45RA. Of interest, ALDH+CD34- population disclosed a straightforward erythroid commitment, on the basis of three orders of evidences. First of all, ALDH+CD34- cells showed a CD71bright, CD105+, CD45- phenotype. Secondly, induction of differentiation experiments evidenced a clear-cut expression of glycophorin A (CD235a). Finally, ALDH+CD34- precursors were not detectable in patients with pure red cell aplasia (PRCA). Conclusion Our study, comparing surface antigen expression of ALDH+/CD34+, ALDH

Ecosystem warming increases sap flow rates of northern red oak trees

DOE PAGES

Juice, Stephanie M.; Templer, Pamela H.; Phillips, Nathan G.; ...

2016-03-17

Over the next century, air temperature increases up to 5°C are projected for the northeastern United States. As evapotranspiration strongly influences water loss from terrestrial ecosystems, the ecophysiological response of trees to warming will have important consequences for forest water budgets. We measured growing season sap flow rates in mature northern red oak ( Quercus rubra L.) trees in a combined air (up to 5.5°C above ambient) and soil (up to 1.85°C above ambient at 6-cm depth) warming experiment at Harvard Forest, Massachusetts, United States. Through principal components analysis, we found air and soil temperatures explained the largest amount ofmore » variance in environmental variables associated with rates of sap flow, with relative humidity, photosynthetically active radiation and vapor pressure deficit having significant, but smaller, effects. On average, each 1°C increase in temperature increased sap flow rates by approximately 1100 kg H 2O m -2 sapwood area day-1 throughout the growing season and by 1200 kg H 2O m -2 sapwood area day -1 during the early growing season. Reductions in the number of cold winter days correlated positively with increased sap flow during the early growing season (a decrease in 100 heating-degree days was associated with a sapflow increase in approximately 5 kg H 2O m -2 sapwood area day -1). Soil moisture declined with increased treatment temperatures, and each soil moisture percentage decrease resulted in a decrease in sap flow of approximately 360 kg H2O m -22 sapwood area day -1. At night, soil moisture correlated positively with sap flow. Finally, these results demonstrate that warmer air and soil temperatures in winter and throughout the growing season lead to increased sap flow rates, which could affect forest water budgets throughout the year.« less

Ecosystem warming increases sap flow rates of northern red oak trees

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

Juice, Stephanie M.; Templer, Pamela H.; Phillips, Nathan G.

Over the next century, air temperature increases up to 5°C are projected for the northeastern United States. As evapotranspiration strongly influences water loss from terrestrial ecosystems, the ecophysiological response of trees to warming will have important consequences for forest water budgets. We measured growing season sap flow rates in mature northern red oak ( Quercus rubra L.) trees in a combined air (up to 5.5°C above ambient) and soil (up to 1.85°C above ambient at 6-cm depth) warming experiment at Harvard Forest, Massachusetts, United States. Through principal components analysis, we found air and soil temperatures explained the largest amount ofmore » variance in environmental variables associated with rates of sap flow, with relative humidity, photosynthetically active radiation and vapor pressure deficit having significant, but smaller, effects. On average, each 1°C increase in temperature increased sap flow rates by approximately 1100 kg H 2O m -2 sapwood area day-1 throughout the growing season and by 1200 kg H 2O m -2 sapwood area day -1 during the early growing season. Reductions in the number of cold winter days correlated positively with increased sap flow during the early growing season (a decrease in 100 heating-degree days was associated with a sapflow increase in approximately 5 kg H 2O m -2 sapwood area day -1). Soil moisture declined with increased treatment temperatures, and each soil moisture percentage decrease resulted in a decrease in sap flow of approximately 360 kg H2O m -22 sapwood area day -1. At night, soil moisture correlated positively with sap flow. Finally, these results demonstrate that warmer air and soil temperatures in winter and throughout the growing season lead to increased sap flow rates, which could affect forest water budgets throughout the year.« less

Flow and transport in the natural environment

NASA Astrophysics Data System (ADS)

Steffen, W. L.

An international symposium on flow and transport in the natural environment was held in early September in Canberra. The meeting, sponsored by the Australian Academy o f Science and hosted by the Division of Environmental Mechanics to mark the official opening of Stage 2 of its laboratory, attracted over 100 scientists representing 10 countries.The symposium, organized around flow and transport processes in soil, plants, and the lower layers of the atmosphere, identified and discussed areas where significant advances have taken place over the past 20 years. In addition, it pointed to gaps and weaknesses in present-day understanding. A quarter of the meeting was devoted to closely related transport processes arising in industrial applications.

Blood flow patterns underlie developmental heart defects

PubMed Central

Midgett, Madeline; Thornburg, Kent

2017-01-01

Although cardiac malformations at birth are typically associated with genetic anomalies, blood flow dynamics also play a crucial role in heart formation. However, the relationship between blood flow patterns in the early embryo and later cardiovascular malformation has not been determined. We used the chicken embryo model to quantify the extent to which anomalous blood flow patterns predict cardiac defects that resemble those in humans and found that restricting either the inflow to the heart or the outflow led to reproducible abnormalities with a dose-response type relationship between blood flow stimuli and the expression of cardiac phenotypes. Constricting the outflow tract by 10–35% led predominantly to ventricular septal defects, whereas constricting by 35–60% most often led to double outlet right ventricle. Ligation of the vitelline vein caused mostly pharyngeal arch artery malformations. We show that both cardiac inflow reduction and graded outflow constriction strongly influence the development of specific and persistent abnormal cardiac structure and function. Moreover, the hemodynamic-associated cardiac defects recapitulate those caused by genetic disorders. Thus our data demonstrate the importance of investigating embryonic blood flow conditions to understand the root causes of congenital heart disease as a prerequisite to future prevention and treatment. NEW & NOTEWORTHY Congenital heart defects result from genetic anomalies, teratogen exposure, and altered blood flow during embryonic development. We show here a novel “dose-response” type relationship between the level of blood flow alteration and manifestation of specific cardiac phenotypes. We speculate that abnormal blood flow may frequently underlie congenital heart defects. PMID:28062416

Enhanced influence of early-spring tropical Indian Ocean SST on the following early-summer precipitation over Northeast China

NASA Astrophysics Data System (ADS)

Han, Tingting; He, Shengping; Wang, Huijun; Hao, Xin

2017-04-01

The relationship between the tropical Indian Ocean (TIO) and East Asian summer monsoon/precipitation has been documented in many studies. However, the precursor signals of summer precipitation in the TIO sea surface temperature (SST), which is important for climate prediction, have drawn little attention. This study identified a strong relationship between early-spring TIO SST and subsequent early-summer precipitation in Northeast China (NEC) since the late 1980s. For 1961-1986, the correlations between early-spring TIO SST and early-summer NEC precipitation were statistically insignificant; for 1989-2014, they were positively significant. Since the late 1980s, the early-spring positive TIO SST anomaly was generally followed by a significant anomalous anticyclone over Japan; that facilitated anomalous southerly winds over NEC, conveying more moisture from the North Pacific. Further analysis indicated that an early TIO SST anomaly showed robust persistence into early summer. However, the early-summer TIO SST anomaly displayed a more significant influence on simultaneous atmospheric circulation and further affected NEC precipitation since the late 1980s. In 1989-2014, the early-summer Hadley and Ferrell cell anomalies associated with simultaneous TIO SST anomaly were much more significant and extended further north to mid-latitudes, which provided a dynamic foundation for the TIO-mid-latitude connection. Correspondingly, the TIO SST anomaly could lead to significant divergence anomalies over the Mediterranean. The advections of vorticity by the divergent component of the flow effectively acted as a Rossby wave source. Thus, an apparent Rossby wave originated from the Mediterranean and propagated east to East Asia; that further influenced the NEC precipitation through modulation to the atmospheric circulation (e.g., surface wind, moisture, vertical motion).

Monitoring circulating prostate tumor cells after tumor resection by in vivo flow cytometry

NASA Astrophysics Data System (ADS)

Ding, Nan; Zhu, Xi; Xie, Chengying; Wei, Dan; Yang, Zhangru; Suo, Yuanzhen; Wei, Xunbin

2018-02-01

Prostate cancer has already become the biggest threat among all cancer types for male people and many people died because of its bone metastases. Circulating tumor cells (CTCs) can be used as early metastasis marker so that the detection of CTCs in blood is meaningful for early diagnosis and treatment. However, the relationship between these therapies and metastasis has not been fully clarified yet. Hence, we built PC3 subcutaneous tumor model and developed in vivo flow cytometer (IVFC) platform to record the dynamics of CTC before and after tumor resection. We found out that tumor resection can reduce CTC quantities instantaneously while having a good control of metastasis. CTC re-occurred 7 days after surgery, which might be correlated with early disseminated and deposited tumors. In conclusion, in vivo flow cytometry (IVFC) is capable of detecting CTC dynamics in prostate subcutaneous tumor model and this method could facilitate further research about relationship between other cancer therapies and circulating tumor cells.

Quantification of left and right atrial kinetic energy using four-dimensional intracardiac magnetic resonance imaging flow measurements.

PubMed

Arvidsson, Per M; Töger, Johannes; Heiberg, Einar; Carlsson, Marcus; Arheden, Håkan

2013-05-15

Kinetic energy (KE) of atrial blood has been postulated as a possible contributor to ventricular filling. Therefore, we aimed to quantify the left (LA) and right (RA) atrial blood KE using cardiac magnetic resonance (CMR). Fifteen healthy volunteers underwent CMR at 3 T, including a four-dimensional phase-contrast flow sequence. Mean LA KE was lower than RA KE (1.1 ± 0.1 vs. 1.7 ± 0.1 mJ, P < 0.01). Three KE peaks were seen in both atria: one in ventricular systole, one during early ventricular diastole, and one during atrial contraction. The systolic LA peak was significantly smaller than the RA peak (P < 0.001), and the early diastolic LA peak was larger than the RA peak (P < 0.05). Rotational flow contained 46 ± 7% of total KE and conserved energy better than nonrotational flow did. The KE increase in early diastole was higher in the LA (P < 0.001). Systolic KE correlated with the combination of atrial volume and systolic velocity of the atrioventricular plane displacement (r(2) = 0.57 for LA and r(2) = 0.64 for RA). Early diastolic KE of the LA correlated with left ventricle (LV) mass (r(2) = 0.28), however, no such correlation was found in the right heart. This suggests that LA KE increases during early ventricular diastole due to LV elastic recoil, indicating that LV filling is dependent on diastolic suction. Right ventricle (RV) relaxation does not seem to contribute to atrial KE. Instead, RA KE generated during ventricular systole may be conserved in a hydraulic "flywheel" and transferred to the RV through helical flow, which may contribute to RV filling.

Predicting functional mitral stenosis after restrictive annuloplasty for ischemic mitral regurgitation.

PubMed

Li, Baotong; Wu, Hengchao; Sun, Hansong; Xu, Jianping; Song, Yunhu; Wang, Wei; Wang, Shuiyun

2018-03-07

Although it has been realized that restrictive mitral valve annuloplasty (MVA) may result in clinically significant functional mitral stenosis (MS), it still cannot be predicted. The purpose of this study was to identify risk factors for clinically significant functional MS following restrictive MVA surgery for chronic ischemic mitral regurgitation (CIMR). 114 patients who underwent restrictive MVA with coronary artery bypass grafting (CABG) for treatment of CIMR were retrospectively reviewed. Clinically significant functional MS was defined as resting transmitral peak pressure gradient (PPG) ≥ 13 mmHg. During the follow-up period (range 6-12 months), 28 (24.56%) patients developed clinically significant functional MS. The PPG at follow-up was significantly higher than that measured in the early postoperative stage (3-5 days after surgery). Moreover, there was a linear correlation between the two measurements (r = 0.398, p < 0.001). Annuloplasty size ≤ 27 mm and early postoperative PPG ≥ 7.4 mmHg could predict clinically significant functional MS at 6-12 months postoperatively. Chronic ischemic mitral regurgitation patients treated with restrictive MVA and CABG have significant increases in PPG postoperatively. Annuloplasty size ≤ 27 mm and early postoperative PPG ≥ 7.4 mmHg can predict clinically significant functional MS at 6-12 months after surgery.

Evaluating groundwater flow using passive electrical measurements

NASA Astrophysics Data System (ADS)

Voytek, E.; Revil, A.; Singha, K.

2016-12-01

Accurate quantification of groundwater flow patterns, both in magnitude and direction, is a necessary component of evaluating any hydrologic system. Groundwater flow patterns are often determined using a dense network of wells or piezometers, which can be limited due to logistical or regulatory constraints. The self-potential (SP) method, a passive geophysical technique that relies on currents generated by water movement through porous materials, is a re-emerging alternative or addition to traditional piezometer networks. Naturally generated currents can be measured as voltage differences at the ground surface using only two electrodes, or a more complex electrode array. While the association between SP measurements and groundwater flow was observed as early as 1890s, the method has seen resurgence in hydrology since the governing equations were refined in the 1980s. The method can be used to analyze hydrologic processes at various temporal and spatial scales. Here we present the results of multiple SP surveys collected a multiple scales (1 to 10s of meters). Here single SP grid surveys are used to evaluate flow patterns through artic hillslopes at a discrete point in time. Additionally, a coupled groundwater and electrical model is used to analyze multiple SP data sets to evaluate seasonal changes in groundwater flow through an alpine meadow.

The early indicators of financial failure: a study of bankrupt and solvent health systems.

PubMed

Coyne, Joseph S; Singh, Sher G

2008-01-01

This article presents a series of pertinent predictors of financial failure based on analysis of solvent and bankrupt health systems to identify which financial measures show the clearest distinction between success and failure. Early warning signals are evident from the longitudinal analysis as early as five years before bankruptcy. The data source includes seven years of annual statements filed with the Securities and Exchange Commission by 13 health systems before they filed bankruptcy. Comparative data were compiled from five solvent health systems for the same seven-year period. Seven financial solvency ratios are included in this study, including four cash liquidity measures, two leverage measures, and one efficiency measure. The results show distinct financial trends between solvent and bankrupt health systems, in particular for the operating-cash-flow-related measures, namely Ratio 1: Operating Cash Flow Percentage Change, from prior to current period; Ratio 2: Operating Cash Flow to Net Revenues; and Ratio 4: Cash Flow to Total Liabilities, indicating sensitivity in the hospital industry to cash flow management. The high dependence on credit from third-party payers is cited as a reason for this; thus, there is a great need for cash to fund operations. Five managerial policy implications are provided to help health system managers avoid financial solvency problems in the future.

Arrested blood flow during false aneurysm formation in the carotid arteries of cattle slaughtered with and without stunning.

PubMed

Gregory, N G; Schuster, P; Mirabito, L; Kolesar, R; McManus, T

2012-02-01

The time to onset of arrested blood flow and the size of false aneurysms in the severed carotid arteries were assessed in 126 cattle during halal slaughter without stunning. Thirty six cattle (29%) showed early arrest of blood flow. In 6%, both the left and right carotid arteries in the same animal stopped bleeding before 60s had elapsed following the neck cut. The time to early arrested blood flow was on average 21s, and this was accompanied by enlargement with false aneurysms which occluded the arteries. In the arteries which were still bleeding at 60s after the neck was cut the artery size was normal. Based on comparative data from different slaughter premises it appeared that making the cut in the neck at the first cervical vertebra instead of the second to fourth cervical vertebrae reduced the frequency of false aneurysm formation and early arrested blood flow. This was confirmed in a separate controlled trial where 100 cattle were stunned with a captive bolt and the arteries were examined following neck cutting at either the C1 or C3 positions. Copyright © 2011 Elsevier Ltd. All rights reserved.

Angiographic flow grading and graft arrangement of arterial conduits.

PubMed

Nakajima, Hiroyuki; Kobayashi, Junjiro; Tagusari, Osamu; Niwaya, Kazuo; Funatsu, Toshihiro; Kawamura, Atsushi; Yagihara, Toshikatsu; Kitamura, Soichiro

2006-11-01

We sought to delineate the effects of competitive and reverse flow on the intermediate-term patency of arterial conduits and examined graft arrangements for maximizing antegrade bypass flow. The angiograms of 2083 bypass grafts in 570 patients who underwent off-pump total arterial revascularization without aortic manipulation since December 2000 were reviewed. The blood flow in the bypass grafts were graded A (antegrade), B (competitive), C (reverse), or O (occlusion). The mean number of distal anastomoses was 3.65 +/- 0.94 per patient. In the early angiography 91.3% (1901/2083) of the bypasses were grade A. Thirty (1.4%) bypasses were grade O, whereas 2.9% (61/2083) were grade B, and 4.4%(91/2083) were grade C. In the multivariate analysis the end-to-side anastomosis (P < .0001), 4 or more distal anastomoses of the conduit (P = .01), native coronary stenosis of less than 75% (P < .0001), and target branch location of the right coronary artery territory (P < .0001) and left circumflex artery territory (P = .02) significantly correlated with grade non-A. The patency rate in the late angiography of the bypasses graded B or C in the early angiography was 7 (28.0%) of 25, whereas that of the bypasses graded A was 164 (89.1%) of 184 (P < .0001). The actuarial graft patency rate of the bypasses graded A was 72.3% at 3 years and was significantly higher than that of the bypasses graded B or C (28.6% at 3 years after surgical intervention, P < .0001). The sufficient antegrade bypass flow had a favorable effect on the graft patency of arterial conduits. The graft arrangement should be adjusted for each patient so as to maximize the antegrade bypass flow and to confirm the advantage of arterial grafts.

Elliptic Flow in Au+Au Collisions at √sNN = 130 GeV

NASA Astrophysics Data System (ADS)

Ackermann, K. H.; Adams, N.; Adler, C.; Ahammed, Z.; Ahmad, S.; Allgower, C.; Amsbaugh, J.; Anderson, M.; Anderssen, E.; Arnesen, H.; Arnold, L.; Averichev, G. S.; Baldwin, A.; Balewski, J.; Barannikova, O.; Barnby, L. S.; Baudot, J.; Beddo, M.; Bekele, S.; Belaga, V. V.; Bellwied, R.; Bennett, S.; Bercovitz, J.; Berger, J.; Betts, W.; Bichsel, H.; Bieser, F.; Bland, L. C.; Bloomer, M.; Blyth, C. O.; Boehm, J.; Bonner, B. E.; Bonnet, D.; Bossingham, R.; Botlo, M.; Boucham, A.; Bouillo, N.; Bouvier, S.; Bradley, K.; Brady, F. P.; Braithwaite, E. S.; Braithwaite, W.; Brandin, A.; Brown, R. L.; Brugalette, G.; Byrd, C.; Caines, H.; Calderón de La Barca Sánchez, M.; Cardenas, A.; Carr, L.; Carroll, J.; Castillo, J.; Caylor, B.; Cebra, D.; Chatopadhyay, S.; Chen, M. L.; Chen, W.; Chen, Y.; Chernenko, S. P.; Cherney, M.; Chikanian, A.; Choi, B.; Chrin, J.; Christie, W.; Coffin, J. P.; Conin, L.; Consiglio, C.; Cormier, T. M.; Cramer, J. G.; Crawford, H. J.; Danilov, V. I.; Dayton, D.; Demello, M.; Deng, W. S.; Derevschikov, A. A.; Dialinas, M.; Diaz, H.; Deyoung, P. A.; Didenko, L.; Dimassimo, D.; Dioguardi, J.; Dominik, W.; Drancourt, C.; Draper, J. E.; Dunin, V. B.; Dunlop, J. C.; Eckardt, V.; Edwards, W. R.; Efimov, L. G.; Eggert, T.; Emelianov, V.; Engelage, J.; Eppley, G.; Erazmus, B.; Etkin, A.; Fachini, P.; Feliciano, C.; Ferenc, D.; Ferguson, M. I.; Fessler, H.; Finch, E.; Fine, V.; Fisyak, Y.; Flierl, D.; Flores, I.; Foley, K. J.; Fritz, D.; Gagunashvili, N.; Gans, J.; Gazdzicki, M.; Germain, M.; Geurts, F.; Ghazikhanian, V.; Gojak, C.; Grabski, J.; Grachov, O.; Grau, M.; Greiner, D.; Greiner, L.; Grigoriev, V.; Grosnick, D.; Gross, J.; Guilloux, G.; Gushin, E.; Hall, J.; Hallman, T. J.; Hardtke, D.; Harper, G.; Harris, J. W.; He, P.; Heffner, M.; Heppelmann, S.; Herston, T.; Hill, D.; Hippolyte, B.; Hirsch, A.; Hjort, E.; Hoffmann, G. W.; Horsley, M.; Howe, M.; Huang, H. Z.; Humanic, T. J.; Hümmler, H.; Hunt, W.; Hunter, J.; Igo, G. J.; Ishihara, A.; Ivanshin, Yu. I.; Jacobs, P.; Jacobs, W. W.; Jacobson, S.; Jared, R.; Jensen, P.; Johnson, I.; Jones, P. G.; Judd, E.; Kaneta, M.; Kaplan, M.; Keane, D.; Kenney, V. P.; Khodinov, A.; Klay, J.; Klein, S. R.; Klyachko, A.; Koehler, G.; Konstantinov, A. S.; Kormilitsyne, V.; Kotchenda, L.; Kotov, I.; Kovalenko, A. D.; Kramer, M.; Kravtsov, P.; Krueger, K.; Krupien, T.; Kuczewski, P.; Kuhn, C.; Kunde, G. J.; Kunz, C. L.; Kutuev, R. Kh.; Kuznetsov, A. A.; Lakehal-Ayat, L.; Lamas-Valverde, J.; Lamont, M. A.; Landgraf, J. M.; Lange, S.; Lansdell, C. P.; Lasiuk, B.; Laue, F.; Lebedev, A.; Lecompte, T.; Leonhardt, W. J.; Leontiev, V. M.; Leszczynski, P.; Levine, M. J.; Li, Q.; Li, Q.; Li, Z.; Liaw, C.-J.; Lin, J.; Lindenbaum, S. J.; Lindenstruth, V.; Lindstrom, P. J.; Lisa, M. A.; Liu, H.; Ljubicic, T.; Llope, W. J.; Locurto, G.; Long, H.; Longacre, R. S.; Lopez-Noriega, M.; Lopiano, D.; Love, W. A.; Lutz, J. R.; Lynn, D.; Madansky, L.; Maier, R.; Majka, R.; Maliszewski, A.; Margetis, S.; Marks, K.; Marstaller, R.; Martin, L.; Marx, J.; Matis, H. S.; Matulenko, Yu. A.; Matyushevski, E. A.; McParland, C.; McShane, T. S.; Meier, J.; Melnick, Yu.; Meschanin, A.; Middlekamp, P.; Mikhalin, N.; Miller, B.; Milosevich, Z.; Minaev, N. G.; Minor, B.; Mitchell, J.; Mogavero, E.; Moiseenko, V. A.; Moltz, D.; Moore, C. F.; Morozov, V.; Morse, R.; de Moura, M. M.; Munhoz, M. G.; Mutchler, G. S.; Nelson, J. M.; Nevski, P.; Ngo, T.; Nguyen, M.; Nguyen, T.; Nikitin, V. A.; Nogach, L. V.; Noggle, T.; Norman, B.; Nurushev, S. B.; Nussbaum, T.; Nystrand, J.; Odyniec, G.; Ogawa, A.; Ogilvie, C. A.; Olchanski, K.; Oldenburg, M.; Olson, D.; Ososkov, G. A.; Ott, G.; Padrazo, D.; Paic, G.; Pandey, S. U.; Panebratsev, Y.; Panitkin, S. Y.; Pavlinov, A. I.; Pawlak, T.; Pentia, M.; Perevotchikov, V.; Peryt, W.; Petrov, V. A.; Pinganaud, W.; Pirogov, S.; Platner, E.; Pluta, J.; Polk, I.; Porile, N.; Porter, J.; Poskanzer, A. M.; Potrebenikova, E.; Prindle, D.; Pruneau, C.; Puskar-Pasewicz, J.; Rai, G.; Rasson, J.; Ravel, O.; Ray, R. L.; Razin, S. V.; Reichhold, D.; Reid, J.; Renfordt, R. E.; Retiere, F.; Ridiger, A.; Riso, J.; Ritter, H. G.; Roberts, J. B.; Roehrich, D.; Rogachevski, O. V.; Romero, J. L.; Roy, C.; Russ, D.; Rykov, V.; Sakrejda, I.; Sanchez, R.; Sandler, Z.; Sandweiss, J.; Sappenfield, P.; Saulys, A. C.; Savin, I.; Schambach, J.; Scharenberg, R. P.; Scheblien, J.; Scheetz, R.; Schlueter, R.; Schmitz, N.; Schroeder, L. S.; Schulz, M.; Schüttauf, A.; Sedlmeir, J.; Seger, J.; Seliverstov, D.; Seyboth, J.; Seyboth, P.; Seymour, R.; Shakaliev, E. I.; Shestermanov, K. E.; Shi, Y.; Shimanskii, S. S.; Shuman, D.; Shvetcov, V. S.; Skoro, G.; Smirnov, N.; Smykov, L. P.; Snellings, R.; Solberg, K.; Sowinski, J.; Spinka, H. M.; Srivastava, B.; Stephenson, E. J.; Stock, R.; Stolpovsky, A.; Stone, N.; Stone, R.; Strikhanov, M.; Stringfellow, B.; Stroebele, H.; Struck, C.; Suaide, A. A.; Sugarbaker, E.; Suire, C.; Symons, T. J.; Takahashi, J.; Tang, A. H.; Tarchini, A.; Tarzian, J.; Thomas, J. H.; Tikhomirov, V.; Szanto de Toledo, A.; Tonse, S.; Trainor, T.; Trentalange, S.; Tokarev, M.; Tonjes, M. B.; Trofimov, V.; Tsai, O.; Turner, K.; Ullrich, T.; Underwood, D. G.; Vakula, I.; van Buren, G.; Vandermolen, A. M.; Vanyashin, A.; Vasilevski, I. M.; Vasiliev, A. N.; Vigdor, S. E.; Visser, G.; Voloshin, S. A.; Vu, C.; Wang, F.; Ward, H.; Weerasundara, D.; Weidenbach, R.; Wells, R.; Wells, R.; Wenaus, T.; Westfall, G. D.; Whitfield, J. P.; Whitten, C.; Wieman, H.; Willson, R.; Wilson, K.; Wirth, J.; Wisdom, J.; Wissink, S. W.; Witt, R.; Wolf, J.; Wood, L.; Xu, N.; Xu, Z.; Yakutin, A. E.; Yamamoto, E.; Yang, J.; Yepes, P.; Yokosawa, A.; Yurevich, V. I.; Zanevski, Y. V.; Zhang, J.; Zhang, W. M.; Zhu, J.; Zimmerman, D.; Zoulkarneev, R.; Zubarev, A. N.

2001-01-01

Elliptic flow from nuclear collisions is a hadronic observable sensitive to the early stages of system evolution. We report first results on elliptic flow of charged particles at midrapidity in Au+Au collisions at sNN = 130 GeV using the STAR Time Projection Chamber at the Relativistic Heavy Ion Collider. The elliptic flow signal, v2, averaged over transverse momentum, reaches values of about 6% for relatively peripheral collisions and decreases for the more central collisions. This can be interpreted as the observation of a higher degree of thermalization than at lower collision energies. Pseudorapidity and transverse momentum dependence of elliptic flow are also presented.

Applicability of Zipper Merge Versus Early Merge in Kentucky Work Zones

DOT National Transportation Integrated Search

2017-12-24

In an effort to improve work zone safety and streamline traffic flows, a number of state transportation agencies (STAs) have experimented with the zipper merge. The zipper merge differs from a conventional, or early, merge in that vehicles do not mer...

Early Detection of Diabetic Retinopathy.

PubMed

Safi, Hamid; Safi, Sare; Hafezi-Moghadam, Ali; Ahmadieh, Hamid

2018-04-18

Diabetic retinopathy (DR) is a primary cause of visual impairment worldwide. Diabetes mellitus may be associated with ophthalmoscopically nonvisible neurovascular damage that progresses before the first clinical signs of DR appear. Reduction of the inner neuroretinal layer thickness on macular optical coherence tomography (OCT), reduced contrast sensitivity primarily at low spatial frequencies, abnormal results in color vision and microperimetry tests, and a prolonged implicit time recorded by multifocal electroretinography have been proposed for detection of early functional and nonvisible structural neuroretinal changes. Vascular abnormalities such as changes in the retinal vessels caliber, architectural indices, and blood flow have been investigated to evaluate the early stages of DR. The results of OCT angiography, retinal vessel oxygen saturation patterns, and elevated levels of circulating blood markers and cytokines have been suggested as early signs of DR. Light-based molecular imaging in rodents has been developed to demonstrate changes in protein expressions in the retinal microvessels as diagnostic biomarkers. Future clinical studies will examine the safety and efficacy of this approach in humans. We summarize all studies related to subclinical DR biomarkers. Copyright © 2018 Elsevier Inc. All rights reserved.

Enhancement of elliptic flow can signal a first-order phase transition in high-energy heavy-ion collisions

NASA Astrophysics Data System (ADS)

Nara, Yasushi; Niemi, Harri; Ohnishi, Akira; Steinheimer, Jan; Luo, Xiaofeng; Stöcker, Horst

2018-02-01

The beam energy dependence of the elliptic flow, v2, is studied in mid-central Au+Au collisions in the energy range of 3≤ √{s_{NN}} ≤ 30 GeV within the microscopic transport model JAM. The results of three different modes of JAM are compared; cascade-, hadronic mean field-, and a new mode with modified equations of state, with a first-order phase transition and with a crossover transition. The standard hadronic mean field suppresses the elliptic flow v2, while the inclusion of the effects of a first-order phase transition (and also of a crossover transition) does enhance the elliptic flow at √{s_{NN}} < 30 GeV. This is due to the high sensitivity of v2 on the early, compression stage, pressure gradients of the systems created in high-energy heavy-ion collisions. The enhancement or suppression of the scaled energy flow, dubbed "elliptic flow", v2= <(px2-py2)/pT2 >, is understood as being due to out-of-plane flow, py > px, i.e. v2 < 0, dubbed out of plane - "squeeze-out", which occurs predominantly in the early, compression stage. Subsequently, the in-plane flow dominates, px > py, in the expansion stage, v2 > 0. The directed flow, v1(y) = < px(y)/pT(y)>, dubbed "bounce-off", is an independent measure of the pressure, which quickly builds up the transverse momentum transfer in the reaction plane. When the spectator matter leaves the participant fireball region, where the highest compression occurs, a hard expansion leads to larger v2. A combined analysis of the three transverse flow coefficients, radial v0 ˜ v_{\\perp}-, directed v1- and elliptic v2- flow of nucleons, in the beam energy range 3≤√{s_{NN}} ≤ 10 GeV, distinguishes the different compression and expansion scenarios: a characteristic dependence on the early stage equation of state is observed. The enhancement of both the elliptic and the transverse radial flow and the simultaneous collapse of the directed flow of nucleons offers a clear signature if a first-order phase transition is realized

Magnetic Amplifier-Based Power-Flow Controller

DOE PAGES

Dimitrovski, Aleksandar; Li, Zhi; Ozpineci, Burak

2015-02-05

The concept of the magnetic amplifier, a common electromagnetic device in electronic applications in the past, has seldom been used in power systems. In this paper, we introduce the magnetic amplifier-based power-flow controller (MAPFC), an innovative low-cost device that adopts the idea of the magnetic amplifier for power-flow control applications. The uniqueness of MAPFC is in the use of the magnetization of the ferromagnetic core, shared by an ac and a dc winding, as the medium to control the ac winding reactance inserted in series with the transmission line to be controlled. Large power flow in the line can bemore » regulated by the small dc input to the dc winding. Moreover, a project on the R&D of an MAPFC has been funded by the U.S. Department of Energy (DOE) and conducted by the Oak Ridge National Laboratory (ORNL), the University of Tennessee-Knoxville, and Waukesha Electric Systems, Inc. since early 2012. Findings from the project are presented along with some results obtained in a laboratory environment.« less

Amino Acid Stability in the Early Oceans

NASA Technical Reports Server (NTRS)

Parker, E. T.; Brinton, K. L.; Burton, A. S.; Glavin, D. P.; Dworkin, J. P.; Bada, J. L.

2015-01-01

It is likely that a variety of amino acids existed in the early oceans of the Earth at the time of the origin and early evolution of life. "Primordial soup", hydrothermal vent, and meteorite based processes could have contributed to such an inventory. Several "protein" amino acids were likely present, however, based on prebiotic synthesis experiments and carbonaceous meteorite studies, non-protein amino acids, which are rare on Earth today, were likely the most abundant. An important uncertainty is the length of time these amino acids could have persisted before their destruction by abiotic and biotic processes. Prior to life, amino acid concentrations in the oceans were likely regulated by circulation through hydro-thermal vents. Today, the entire ocean circulates through vent systems every 10(exp 7) years. On the early Earth, this value was likely smaller due to higher heat flow and thus marine amino acid life-time would have been shorter. After life, amino acids in the oceans could have been assimilated by primitive organisms.

Identifying High-Rate Flows Based on Sequential Sampling

NASA Astrophysics Data System (ADS)

Zhang, Yu; Fang, Binxing; Luo, Hao

We consider the problem of fast identification of high-rate flows in backbone links with possibly millions of flows. Accurate identification of high-rate flows is important for active queue management, traffic measurement and network security such as detection of distributed denial of service attacks. It is difficult to directly identify high-rate flows in backbone links because tracking the possible millions of flows needs correspondingly large high speed memories. To reduce the measurement overhead, the deterministic 1-out-of-k sampling technique is adopted which is also implemented in Cisco routers (NetFlow). Ideally, a high-rate flow identification method should have short identification time, low memory cost and processing cost. Most importantly, it should be able to specify the identification accuracy. We develop two such methods. The first method is based on fixed sample size test (FSST) which is able to identify high-rate flows with user-specified identification accuracy. However, since FSST has to record every sampled flow during the measurement period, it is not memory efficient. Therefore the second novel method based on truncated sequential probability ratio test (TSPRT) is proposed. Through sequential sampling, TSPRT is able to remove the low-rate flows and identify the high-rate flows at the early stage which can reduce the memory cost and identification time respectively. According to the way to determine the parameters in TSPRT, two versions of TSPRT are proposed: TSPRT-M which is suitable when low memory cost is preferred and TSPRT-T which is suitable when short identification time is preferred. The experimental results show that TSPRT requires less memory and identification time in identifying high-rate flows while satisfying the accuracy requirement as compared to previously proposed methods.

Achieving Maximum Integration Utilizing Requirements Flow Down

NASA Technical Reports Server (NTRS)

Archiable, Wes; Askins, Bruce

2011-01-01

A robust and experienced systems engineering team is essential for a successful program. It is often a challenge to build a core systems engineering team early enough in a program to maximize integration and assure a common path for all supporting teams in a project. Ares I was no exception. During the planning of IVGVT, the team had many challenges including lack of: early identification of stakeholders, team training in NASA s system engineering practices, solid requirements flow down and a top down documentation strategy. The IVGVT team started test planning early in the program before the systems engineering framework had been matured due to an aggressive schedule. Therefore the IVGVT team increased their involvement in the Constellation systems engineering effort. Program level requirements were established that flowed down to IVGVT aligning all stakeholders to a common set of goals. The IVGVT team utilized the APPEL REQ Development Management course providing the team a NASA focused model to follow. The IVGVT team engaged directly with the model verification and validation process to assure that a solid set of requirements drove the need for the test event. The IVGVT team looked at the initial planning state, analyzed the current state and then produced recommendations for the ideal future state of a wide range of systems engineering functions and processes. Based on this analysis, the IVGVT team was able to produce a set of lessons learned and to provide suggestions for future programs or tests to use in their initial planning phase.

Investigating the Flow and Biomechanics of the Embryonic Zebrafish Heart

NASA Astrophysics Data System (ADS)

Johnson, Brennan; Garrity, Deborah; Dasi, Lakshmi

2010-11-01

Understanding flow and kinematic characteristics of the embryonic heart is a prerequisite to devise early intervention or detection methods in the context of congenital heart defects. In this study, the kinematics and fluid dynamics of the embryonic zebrafish heart were analyzed through the early stages of cardiac development (24-48 hours post-fertilization) in vivo using optical microscopy and high-speed video. Endocardial walls and individual blood cells were segmented from raw images and were tracked through the cardiac cycle. Particle tracking velocimetry analysis yielded quantitative blood cell velocity field, chamber volume, and flow rate information. It was seen that the pumping mechanism starts as a combined peristaltic and suction pump while the heart is in the tube configuration and transforms into a positive displacement pump after cardiac looping. Strong two-phase nature of the fluid is evident. This work provides us new understanding of the spatio-temporal characteristics of kinematics and blood cell velocity field inside the developing heart.

Discourses of Professional Identity in Early Childhood: Movements in Australia

ERIC Educational Resources Information Center

Woodrow, Christine

2008-01-01

The provision of early childhood education and care for children and families has received unprecedented community attention in recent times. In the resulting policy flows, competing and contradictory discourses of professional identity have emerged. In part, these are also shaped by dominant political and economic discourses, and interact with…

Specific Impulse and Mass Flow Rate Error

NASA Technical Reports Server (NTRS)

Gregory, Don A.

2005-01-01

Specific impulse is defined in words in many ways. Very early in any text on rocket propulsion a phrase similar to .specific impulse is the thrust force per unit propellant weight flow per second. will be found.(2) It is only after seeing the mathematics written down does the definition mean something physically to scientists and engineers responsible for either measuring it or using someone.s value for it.

Aquatic insect emergence from headwater streams flowing through regeneration and mature forests in western Oregon

Treesearch

Robert Progar; Andrew R. Moldenke

2009-01-01

We examined the effect of canopy cover on adult aquatic insect emergence by collecting bi-weekly samples from twelve headwater stream reaches flowing either under a mature conifer canopy or streams flowing through ten-year-old regeneration in western Oregon from February to November 1997. Density and biomass generally followed a bimodal curve with peaks during early...

Effect of pyrrolidone-pyroglutamic acid composition on blood flow in rat middle cerebral artery.

PubMed

Semkina, G A; Matsievskii, D D; Mirzoyan, N R

2006-01-01

We compared the effects of a pyrrolidone-pyroglutamic acid composition and nimodipine on blood circulation in the middle cerebral artery in rats. The composition produced a strong effect on blood supply to the brain, stimulated blood flow in the middle cerebral artery (by 60 +/- 9%) and decreased blood pressure (by 25.0 +/- 2.7%). The cerebrovascular effects of this composition differed from those of nimodipine. Nimodipine not only increased middle cerebral artery blood flow, but also decreased cerebral blood flow in the early period after treatment.

Calculational investigation of impact cratering dynamics - Early time material motions

NASA Technical Reports Server (NTRS)

Thomsen, J. M.; Austin, M. G.; Ruhl, S. F.; Schultz, P. H.; Orphal, D. L.

1979-01-01

Early time two-dimensional finite difference calculations of laboratory-scale hypervelocity (6 km/sec) impact of 0.3 g spherical 2024 aluminum projectiles into homogeneous plasticene clay targets were performed and the resulting material motions analyzed. Results show that the initial jetting of vaporized target material is qualitatively similar to experimental observation. The velocity flow field developed within the target is shown to have features quite similar to those found in calculations of near-surface explosion cratering. Specific application of Maxwell's analytic Z-Model (developed to interpret the flow fields of near-surface explosion cratering calculations), shows that this model can be used to describe the flow fields resulting from the impact cratering calculations, provided that the flow field center is located beneath the target surface, and that application of the model is made late enough in time that most of the projectile momentum has been dissipated.

Charge-flow structures as polymeric early-warning fire alarm devices. M.S. Thesis; [metal oxide semiconductors

NASA Technical Reports Server (NTRS)

Sechen, C. M.; Senturia, S. D.

1977-01-01

The charge-flow transistor (CFT) and its applications for fire detection and gas sensing were investigated. The utility of various thin film polymers as possible sensing materials was determined. One polymer, PAPA, showed promise as a relative humidity sensor; two others, PFI and PSB, were found to be particularly suitable for fire detection. The behavior of the charge-flow capacitor, which is basically a parallel-plate capacitor with a polymer-filled gap in the metallic tip electrode, was successfully modeled as an RC transmission line. Prototype charge-flow transistors were fabricated and tested. The effective threshold voltage of this metal oxide semiconductor was found to be dependent on whether surface or bulk conduction in the thin film was dominant. Fire tests with a PFI-coated CFT indicate good sensitivity to smouldering fires.

The Extremely Warm Early Winter 2000 in Europe: What is the Forcing

NASA Technical Reports Server (NTRS)

Otterman, J.; Angell, J. K.; Atlas, R.; Ardizzone, J.; Demaree, G.; Jusem, J. C.; Koslowsky, D.; Terry, J.; Einaudi, Franco (Technical Monitor)

2001-01-01

High variability characterizes the winter climate of central Europe: interannual fluctuations in the surface-air temperature as large as 18 C over large areas are fairly common. The extraordinary early-winter 2000 in Europe appears to be a departure to an unprecedented extreme of the existing climate patterns. Such anomalous events affect agriculture, forestry, fuel consumption, etc., and thus deserve in-depth analysis. Our analysis indicates that the high anomalies of the surface-air temperature are predominantly due to the southwesterly flow from the eastern North Atlantic, with a weak contribution by southerly flow from the western Mediterranean. Backward trajectories based on the SSM/I and NCEP Reanalysis datasets traced from west-central Europe indicate that the warm air masses flowing into Europe originate in the southern North Atlantic, where the surface-air temperatures exceed by 15c or more the climatic norms in Europe for late-November or early-December. Because such large ocean-to-continent temperature differences characterize the winter conditions, we refer to this episode which started in late November as occurring in the early winter. In this season, with the sun low over the horizon in Europe, absorption of insolation by the surface has little significance. The effect of cloudiness, a corollary to the low-level maritime-air advection, is a warming by a reduction of heat loss (greenhouse effect). In contrast, in the summer, clouds, by reducing absorption of insolation, produce a cooling, effect at the surface.

Urine flow is a novel hemodynamic monitoring tool for the detection of hypovolemia.

PubMed

Shamir, Micha Y; Kaplan, Leonid; Marans, Rachel S; Willner, Dafna; Klein, Yoram

2011-03-01

Noticeable changes in vital signs indicating hypovolemia occur only after 15% of the blood volume is lost. More sensitive variables (e.g., cardiac output, systolic pressure variation and its Δdown component) are invasive and difficult to obtain in the early phase of bleeding. Lately, a new technology for continuous optical measurements of minute-to-minute urine flow rates has become available. We performed a preliminary evaluation to determine whether urine flow can act as an early and sensitive warning of hypovolemia. Eleven patients (ASA physical status I-II) undergoing posterior spine fusion surgery were studied prospectively. Study variables included heart rate, blood pressure (systolic and diastolic), systolic pressure variation and Δdown, minute urinary flow, hemoglobin, blood and urinary sodium, and creatinine in the blood and urine. Urine flow rate was measured using URINFO 2000™ (FlowSense Medical, Misgav, Israel). After recording baseline variables, 10 mL/kg of the patient's blood was shed and a second set of variables was recorded. Subsequently, hypovolemia was reversed by infusing colloid solution (hetastarch 6%) followed by recording a third set of variables. These 3 observations were then compared. An average of 614 ± 143 mL (mean ± SD) of blood was shed. During phlebotomy, the mean urine flow rate decreased from 5.7 ± 8 mL/min to 1.07 ± 2.5 mL/min. Systolic blood pressure and hemoglobin also decreased. Δdown increased. After rehydration, urine flow, blood pressure, and Δdown values returned to baseline. The hemoglobin concentration decreased whereas other variables did not change significantly. Urine flow rate is a dynamic variable that seems to be a reliable indicator of changes in blood volume. These results justify further investigation.

Early genetic consequences of defaunation in a large-seeded vertebrate-dispersed palm (Syagrus romanzoffiana)

PubMed Central

Giombini, M I; Bravo, S P; Sica, Y V; Tosto, D S

2017-01-01

Plant populations are seriously threatened by anthropogenic habitat disturbance. In particular, defaunation may disrupt plant-disperser mutualisms, thus reducing levels of seed-mediated gene flow and genetic variation in animal-dispersed plants. This may ultimately limit their adaptive potential and ability to cope with environmental change. Tropical forest remnants are typically deprived of medium to large vertebrates upon which many large-seeded plants rely for accomplishing effective seed dispersal. Our main goal was to examine the potential early genetic consequences of the loss of large vertebrates for large-seeded vertebrate-dispersed plants. We compared the genetic variation in early-stage individuals of the large-seeded palm Syagrus romanzoffiana between continuous protected forest and nearby partially defaunated fragments in the Atlantic Forest of South America. Using nine microsatellites, we found lower allelic richness and stronger fine-scale spatial genetic structure in the disturbed area. In addition, the percentage of dispersed recruits around conspecific adults was lower, although not significantly, in the disturbed area (median values: 0.0 vs 14.4%). On the other hand, no evidence of increased inbreeding or reduced pollen-mediated gene flow (selfing rate and diversity of pollen donors) was found in the disturbed area. Our findings are strongly suggestive of some early genetic consequences resulting from the limitation in contemporary gene flow via seeds, but not pollen, in defaunated areas. Plant-disperser mutualisms involving medium–large frugivores, which are seriously threatened in tropical systems, should therefore be protected to warrant the maintenance of seed-mediated gene flow and genetic diversity in large-seeded plants. PMID:28121308

Visualization of early post-implantation mouse embryogenesis using 3D imaging modality (Conference Presentation)

NASA Astrophysics Data System (ADS)

Hsu, Chih-Wei; Le, Henry H.; Li-Villarreal, Nanbing; Piazza, Victor G.; Kalaga, Sowmya; Dickinson, Mary E.

2017-02-01

Hemodynamic force is vital to cardiovascular remodeling in the early post-implantation mouse embryo. Here, we present work using microCT and lightsheet microscopy to establish the critical sequence of developmental events required for forming functional vasculature and circulation in the embryo, yolk sac, and placenta in the context of normal and impaired flow. A flow impaired model, Mlc2a+/- will be used to determine how hemodynamic force affects the specific events during embryonic development and vascular remodeling between the 4 and 29-somite stage using microCT. We have recently established high-resolution methods for the generation of 3D image volumes from the whole embryo within the deciduum (Hsu et al., in revision). This method enables the careful characterization of 3D images of vitelline and umbilical vessel remodeling to define how poor blood flow impacts both vitelline and umbilical vessel remodeling. Novel lightsheet live imaging techniques will be used to determine the consequence of impaired blood flow on yolk sac vasculature remodeling and formation of umbilical vessels using transgenic reporters: Flk-myr::mCherry, Flk1-H2B::YFP, or ɛGlobin-GFP. High-resolution 3D imaging of fixed and ScaleA2-cleared whole mount embryos labeled with Ki67 and Caspase3 will also be performed using lightsheet microscopy to quantify the proliferation and apoptotic indexes of early post-implanted embryos and yolk sac. This multi-modality approach is aimed at revealing further information about the cellular mechanisms required for proper vessel remodeling and the initial stages in placentation during early post-implantation development.

Difficulties in Forecasting Flow Paths During the 2014-2015 Lava Flow Crisis at Kīlauea Volcano (Hawaíi)

NASA Astrophysics Data System (ADS)

Patrick, M. R.; Orr, T. R.; Trusdell, F.; Llewellin, E. W.; Kauahikaua, J. P.

2015-12-01

Kīlauea's East Rift Zone (ERZ) eruptive activity at Púu ´Ō´ō shifted to a new vent in June 2014, sparking a lava flow crisis that threatened critical infrastructure near the town of Pāhoa in east Hawaíi. The lava flow proved to be challenging to forecast because of the influence of ground cracks on flow direction, frequent fluctuations in lava supply, and the subtle interplay between ground slope and confining topography that prevented the flow from spreading laterally. After its onset, the "June 27th" flow, named informally for its start date, advanced northeast at up to several hundred m/day. The flow's path through heavy forest was forecast using steepest-descent paths derived from a digital elevation model (DEM). Flow path uncertainties were minimized using a multiple-run technique and built-in random DEM errors (modified from Favalli et al., 2005). In mid-August, the flow encountered and entered one of many deep, discontinuous ground cracks along Kīlauea's middle ERZ. The flow continued to advance out of sight in the crack, as inferred from a forward-progressing line of steam. A week later, lava spilled from the crack 1.3 km downslope, advancing along a different flow path than was forecast. By early September, the flow had entered and exited three more cracks sequentially, carrying the flow across slope, thus making flow path forecasts unreliable. Moreover, lava-occupied cracks dilated by up to 3 m. The lava accumulating in the ground cracks forced immense, but apparently mobile, blocks to shift. Thus, while an open crack was required to capture the lava, the lava was able to force its way beyond where the crack closed. In this way, the lava flow acted as an intruding dike. The flow eventually advanced beyond the area of cracks and onto a steepest-descent path that guided the flow toward the town of Pāhoa, where it destroyed one house, reached to within ~155 m of the main street in Pāhoa, and threatened the main highway and shopping center serving

Use of Instream Flow Incremental Methodology: introduction to the special issue

USGS Publications Warehouse

Lamb, Berton Lee; Sabaton, C.; Souchon, Y.

2004-01-01

In 1991, Harvey Doerksen was able to write a memoir discussing 20 years of instream flow work (Doerksen 1991). He recalled coming into the field in about 1973, but points out that there were many dedicated professionals working on the front line of what has become known as the environmental flow issue since at least the 1940’s. One of the earliest controversies in this new field was about what to call it. Some of the can- didate titles included “Stream Re- source Maintenance Flow,” “Base Flow,” and “Minimum Flow.” Although some of these terms were already in wide use by the early 1970’s, the term “instream flow” was not even listed in the 1973, 1974, or 1975 editions of the Water Resources Research Catalog of keywords (Doerksen 1991: 100). When most of the authors represented in this special issue began their professional careers, the field of instream flow was still seeking a core identity and a set of organizing principles.

Evaluating ocular blood flow

PubMed Central

Maram, Jyotsna; Srinivas, Sowmya; Sadda, Srinivas R

2017-01-01

Studies have shown that vascular impairment plays an important role in the etiology and pathogenesis of various ocular diseases including glaucoma, age-related macular degeneration, diabetic retinopathy, and retinal venous occlusive disease. Thus, qualitative and quantitative assessment of ocular blood flow (BF) is a topic of interest for early disease detection, diagnosis, and management. Owing to the rapid improvement in technology, there are several invasive and noninvasive techniques available for evaluating ocular BF, with each of these techniques having their own limitations and advantages. This article reviews these important techniques, with a particular focus on Doppler Fourier domain optical coherence tomography (OCT) and OCT-angiography. PMID:28573987

Heterogeneity of human adipose blood flow

PubMed Central

Levitt, David G

2007-01-01

Background The long time pharmacokinetics of highly lipid soluble compounds is dominated by blood-adipose tissue exchange and depends on the magnitude and heterogeneity of adipose blood flow. Because the adipose tissue is an infinite sink at short times (hours), the kinetics must be followed for days in order to determine if the adipose perfusion is heterogeneous. The purpose of this paper is to quantitate human adipose blood flow heterogeneity and determine its importance for human pharmacokinetics. Methods The heterogeneity was determined using a physiologically based pharmacokinetic model (PBPK) to describe the 6 day volatile anesthetic data previously published by Yasuda et. al. The analysis uses the freely available software PKQuest and incorporates perfusion-ventilation mismatch and time dependent parameters that varied from the anesthetized to the ambulatory period. This heterogeneous adipose perfusion PBPK model was then tested by applying it to the previously published cannabidiol data of Ohlsson et. al. and the cannabinol data of Johansson et. al. Results The volatile anesthetic kinetics at early times have only a weak dependence on adipose blood flow while at long times the pharmacokinetics are dominated by the adipose flow and are independent of muscle blood flow. At least 2 adipose compartments with different perfusion rates (0.074 and 0.014 l/kg/min) were needed to describe the anesthetic data. This heterogeneous adipose PBPK model also provided a good fit to the cannabinol data. Conclusion Human adipose blood flow is markedly heterogeneous, varying by at least 5 fold. This heterogeneity significantly influences the long time pharmacokinetics of the volatile anesthetics and tetrahydrocannabinol. In contrast, using this same PBPK model it can be shown that the long time pharmacokinetics of the persistent lipophilic compounds (dioxins, PCBs) do not depend on adipose blood flow. The ability of the same PBPK model to describe both the anesthetic and

Procollagen type III amino terminal peptide and myocardial fibrosis: A study in hypertensive patients with and without left ventricular hypertrophy.

PubMed

dos Santos Moreira, Carlos; Serejo, Fátima; Alcântara, Paula; Ramalhinho, Vítor; Braz Nogueira, J

2015-05-01

An exaggerated accumulation of type I and type III fibrillar collagens occurs throughout the free wall and interventricular septum of patients with primary hypertension and left ventricular hypertrophy (LVH). In the present study the serum concentration of procollagen type III amino terminal peptide (PIIIP) was measured to determine the value of this peptide as a potential marker of ventricular fibrosis in hypertensive patients, particularly those with LVH. The study population consisted of patients with never-treated mild to moderate essential hypertension and 30 normotensive control subjects. Clinical, echocardiographic, electrocardiographic and biochemical parameters were assessed in all patients. Heart rate, body mass index and levels of blood pressure were increased in hypertensives, particularly those with LVH, compared to normotensive controls. Posterior wall thickness, left ventricular (LV) mass and LV mass index, and serum PIIIP concentration were also increased in hypertensives, with significant differences between the two hypertensive groups. The ratio between maximal early and late transmitral flow velocity measured during diastole was lower in hypertensives, particularly those with LVH, than in normotensive controls. The increase in PIIIP indicates that type III collagen synthesis increases in hypertensives, particularly those with LVH, implying that alterations in the heart in hypertension are the result not solely of hypertrophied LV muscle, but also of increased collagen deposition within the ventricular wall and around the coronary vessels. Thus, measurement of serum PIIIP could be a practical and useful tool in the non-invasive assessment of myocardial remodeling in hypertension. Copyright © 2014 Sociedade Portuguesa de Cardiologia. Published by Elsevier España. All rights reserved.

Spatiotemporal analysis of gene flow in Chesapeake Bay Diamondback Terrapins (Malaclemys terrapin)

USGS Publications Warehouse

Converse, Paul E.; Kuchta, Shawn R; Roosenburg, Willem R; Henry, Paula F.; Haramis, G. Michael; King, Timothy L.

2015-01-01

There is widespread concern regarding the impacts of anthropogenic activities on connectivity among populations of plants and animals, and understanding how contemporary and historical processes shape metapopulation dynamics is crucial for setting appropriate conservation targets. We used genetic data to identify population clusters and quantify gene flow over historical and contemporary time frames in the Diamondback Terrapin (Malaclemys terrapin). This species has a long and complicated history with humans, including commercial over-harvesting and subsequent translocation events during the early twentieth century. Today, terrapins face threats from habitat loss and mortality in fisheries bycatch. To evaluate population structure and gene flow among Diamondback Terrapin populations in the Chesapeake Bay region, we sampled 617 individuals from 15 localities, and screened individuals at 12 polymorphic microsatellite loci. Our goals were to demarcate metapopulation structure, quantify genetic diversity, estimate effective population sizes, and document temporal changes in gene flow. We found that terrapins in the Chesapeake Bay region harbor high levels of genetic diversity and form four populations. Effective population sizes were variable. Among most population comparisons, estimates of historical and contemporary terrapin gene flow were generally low (m ≈ 0.01). However, we detected a substantial increase in contemporary gene flow into Chesapeake Bay from populations outside the bay, as well as between two populations within Chesapeake Bay, possibly as a consequence of translocations during the early twentieth century. Our study shows that inferences across multiple time scales are needed to evaluate population connectivity, especially as recent changes may identify threats to population persistence.

Fitness in Young Adulthood and Long-Term Cardiac Structure and Function: The CARDIA Study.

PubMed

Pandey, Ambarish; Allen, Norrina B; Ayers, Colby; Reis, Jared P; Moreira, Henrique T; Sidney, Stephen; Rana, Jamal S; Jacobs, David R; Chow, Lisa S; de Lemos, James A; Carnethon, Mercedes; Berry, Jarett D

2017-05-01

This study sought to evaluate the association between early-life cardiorespiratory fitness (CRF) and measures of left ventricular (LV) structure and function in midlife. Low CRF in midlife is associated with a higher risk of heart failure. However, the unique contributions of early-life CRF toward measures of LV structure and function in middle age are not known. CARDIA (Coronary Artery Risk Development in Young Adults) study participants with a baseline maximal treadmill test and an echocardiogram at year 25 were included. Associations among baseline CRF, CRF change, and echocardiographic LV parameters (global longitudinal strain [GLS] and global circumferential strain, E/e') were assessed using multivariable linear regression. The study included 3,433 participants. After adjustment for baseline demographic and clinical characteristics, lower baseline CRF was significantly associated with higher LV strain (standardized parameter estimate [Std β] = -0.06; p = 0.03 for GLS) and ratio of early transmitral flow velocity to early peak diastolic mitral annular velocity (E/e') (Std β = -0.10; p = 0.0001 for lateral E/e'), findings suggesting impaired contractility and elevated diastolic filling pressure in midlife. After additional adjustment for cumulative cardiovascular risk factor burden observed over the follow-up period, the association of CRF with LV strain attenuated substantially (p = 0.36), whereas the association with diastolic filling pressure remained significant (Std β = -0.05; p = 0.02 for lateral E/e'). In a subgroup of participants with repeat CRF tests at year 20, greater decline in CRF was significantly associated with increased abnormalities in GLS (Std β = -0.05; p = 0.02) and higher diastolic filling pressure (Std β = -0.06; p = 0.006 for lateral E/e') in middle age. CRF in young adulthood and CRF change were associated with measures of LV systolic function and diastolic filling pressure in middle age. Low CRF

Longitudinal Cerebral Blood Flow Changes during Speech in Hereditary Ataxia

ERIC Educational Resources Information Center

Sidtis, John J.; Strother, Stephen C.; Naoum, Ansam; Rottenberg, David A.; Gomez, Christopher

2010-01-01

The hereditary ataxias constitute a group of degenerative diseases that progress over years or decades. With principal pathology involving the cerebellum, dysarthria is an early feature of many of the ataxias. Positron emission tomography was used to study regional cerebral blood flow changes during speech production over a 21 month period in a…

Teacher Responses to Learning Cycle Science Lessons for Early Childhood Education

NASA Astrophysics Data System (ADS)

Kraemer, Emily N.

Three learning cycle science lessons were developed for preschoolers in an early childhood children's center in Costa Mesa, California. The lessons were field tested by both novice and experienced teachers with children ranging from three to five years old. Teachers were then interviewed informally to collect feedback on the structure and flow the lessons. The feedback was encouraging remarks towards the use of learning cycle science lessons for early childhood educators. Adjustments were made to the lessons based on teacher feedback. The lessons and their implications for preschool education are discussed.

Flow and Noise Control: Toward a Closer Linkage

NASA Technical Reports Server (NTRS)

Thomas, Russell H.; Choudhari, Meelan M.; Joslin, Ronald D.

2002-01-01

Motivated by growing demands for aircraft noise reduction and for revolutionary new aerovehicle concepts, the late twentieth century witnessed the beginning of a shift from single-discipline research, toward an increased emphasis on harnessing the potential of flow and noise control as implemented in a more fully integrated, multidisciplinary framework. At the same time, technologies for developing radically new aerovehicles, which promise quantum leap benefits in cost, safety and performance benefits with environmental friendliness, have appeared on the horizon. Transitioning new technologies to commercial applications will also require coupling further advances in traditional areas of aeronautics with intelligent exploitation of nontraditional and interdisciplinary technologies. Physics-based modeling and simulation are crucial enabling capabilities for synergistic linkage of flow and noise control. In these very fundamental ways, flow and noise control are being driven to be more closely linked during the early design phases of a vehicle concept for optimal and mutual noise and performance benefits.

A global hydrographic array for early detection of floods and droughts

NASA Astrophysics Data System (ADS)

Brakenridge, G.; Nghiem, S.; Caquard, S.

An array of over 700 20 km-long river gaging reaches, distributed world-wide, is imaged by the SeaWinds radar scatterometer aboard QuikSCAT every 2.5 days. Strongly negative HH/VV polarity ratios indicate large amounts of surface water. We set individual reach thresholds so that the transition from bankfull to overbank river flow can be identified according to changes in this ratio. Similarly, the wide-swath MODIS optical sensors provide frequent repeat coverage of the reaches at much higher spatial resolution (250 m). In this case, several reach water surface area thresholds can be identified: low flow or drought conditions, normal in-channel flow, overbank flow, and extreme flood conditions. Sustained data collection for the reaches by both sensors allows the radar response to changing surface water to be defined, and allows evaluation of the sensitivity of the MODIS data to river discharge changes. New approaches, such as ``unmixing'' analysis of mixed water/land MODIS pixels can extend detection limits to smaller rivers and streams. It is now possible for wide-area, frequent revisit terrestrial remote sensing to provide human society with early warning of both floods and droughts and by direct observation of the runoff component of the Earth's hydrologic cycle. Examples of both radar and optical approaches towards this end are at the web sites below: http://www.dartmouth.edu/˜ floods/Modisrapidresponse.html http://www.dartmouth.edu/˜ floods/sensorweb/SensorWebindex.html http://www.dartmouth.edu/˜ floods/Quikscat/Regional2/CurrentTisza.jpg} In particular, early flood detection results are obtained over an extensive region in eastern Europe including the Tisza River basin, Romania, Hungary, and adjacent nations. Flood detection maps are updated weekly at the web site. The combination of QuikSCAT and MODIS takes advantage of the large-area coverage of these sensors together with the high temporal resolution of QuikSCAT and the high spatial resolution of MODIS

Simulation of Flow Through Breach in Leading Edge at Mach 24

NASA Technical Reports Server (NTRS)

Gnoffo, Peter A.; Alter, Stephen J.

2004-01-01

A baseline solution for CFD Point 1 (Mach 24) in the STS-107 accident investigation was modified to include effects of holes through the leading edge into a vented cavity. The simulations were generated relatively quickly and early in the investigation by making simplifications to the leading edge cavity geometry. These simplifications in the breach simulations enabled: 1) A very quick grid generation procedure; 2) High fidelity corroboration of jet physics with internal surface impingements ensuing from a breach through the leading edge, fully coupled to the external shock layer flow at flight conditions. These simulations provided early evidence that the flow through a 2 inch diameter (or larger) breach enters the cavity with significant retention of external flow directionality. A normal jet directed into the cavity was not an appropriate model for these conditions at CFD Point 1 (Mach 24). The breach diameters were of the same order or larger than the local, external boundary-layer thickness. High impingement heating and pressures on the downstream lip of the breach were computed. It is likely that hole shape would evolve as a slot cut in the direction of the external streamlines. In the case of the 6 inch diameter breach the boundary layer is fully ingested.

Ancient gene flow from early modern humans into Eastern Neanderthals

PubMed Central

Kuhlwilm, Martin; Gronau, Ilan; Hubisz, Melissa J.; de Filippo, Cesare; Prado-Martinez, Javier; Kircher, Martin; Fu, Qiaomei; Burbano, Hernán A.; Lalueza-Fox, Carles; de la Rasilla, Marco; Rosas, Antonio; Rudan, Pavao; Brajkovic, Dejana; Kucan, Željko; Gušic, Ivan; Marques-Bonet, Tomas; Andrés, Aida M.; Viola, Bence; Pääbo, Svante; Meyer, Matthias; Siepel, Adam; Castellano, Sergi

2016-01-01

It has been shown that Neanderthals contributed genetically to modern humans outside Africa 47,000–65,000 years ago. Here, we analyze the genomes of a Neanderthal and a Denisovan from the Altai Mountains in Siberia together with the sequences of chromosome 21 of two Neanderthals from Spain and Croatia. We find that a population that diverged early from other modern humans in Africa contributed genetically to the ancestors of Neanderthals from the Altai Mountains roughly 100,000 years ago. By contrast, we do not detect such a genetic contribution in the Denisovan or the two European Neanderthals. We conclude that in addition to later interbreeding events, the ancestors of Neanderthals from the Altai Mountains and of modern humans met and interbred, possibly in the Near East, many thousands of years earlier than previously reported. PMID:26886800

Intracardiac Vortex Dynamics by High-Frame-Rate Doppler Vortography-In Vivo Comparison With Vector Flow Mapping and 4-D Flow MRI.

PubMed

Faurie, Julia; Baudet, Mathilde; Assi, Kondo Claude; Auger, Dominique; Gilbert, Guillaume; Tournoux, Francois; Garcia, Damien

2017-02-01

Recent studies have suggested that intracardiac vortex flow imaging could be of clinical interest to early diagnose the diastolic heart function. Doppler vortography has been introduced as a simple color Doppler method to detect and quantify intraventricular vortices. This method is able to locate a vortex core based on the recognition of an antisymmetric pattern in the Doppler velocity field. Because the heart is a fast-moving organ, high frame rates are needed to decipher the whole blood vortex dynamics during diastole. In this paper, we adapted the vortography method to high-frame-rate echocardiography using circular waves. Time-resolved Doppler vortography was first validated in vitro in an ideal forced vortex. We observed a strong correlation between the core vorticity determined by high-frame-rate vortography and the ground-truth vorticity. Vortography was also tested in vivo in ten healthy volunteers using high-frame-rate duplex ultrasonography. The main vortex that forms during left ventricular filling was tracked during two-three successive cardiac cycles, and its core vorticity was determined at a sampling rate up to 80 duplex images per heartbeat. Three echocardiographic apical views were evaluated. Vortography-derived vorticities were compared with those returned by the 2-D vector flow mapping approach. Comparison with 4-D flow magnetic resonance imaging was also performed in four of the ten volunteers. Strong intermethod agreements were observed when determining the peak vorticity during early filling. It is concluded that high-frame-rate Doppler vortography can accurately investigate the diastolic vortex dynamics.

Narcolepsy: regional cerebral blood flow during sleep and wakefulness

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

Sakai, F.; Meyer, J.S.; Karacan, I.

Serial measurements of regional cerebral blood flow were made by the 135Xe inhalation method during the early stages of sleep and wakefulness in eight normal volunteers and 12 patients with narcolepsy. Electroencephalogram, electro-oculogram, and submental electromyogram were recorded simultaneously. In normals, mean hemispheric gray matter blood flow (Fg) during stages I and II sleep was significantly less than waking values. Maximum regional blood flow decreases during sleep occurred in the brainstem-cerebellar, right inferior temporal, and bilateral frontal regions. In patients with narcolepsy, mean hemispheric Fg while awake was 80.5 +- 13 ml per 100 gm brain per minute. During REMmore » sleep, mean hemispheric Fg increased concurrently with large increases in brainstem-cerebellar region flow. During stages I and II sleep without REM, there were significant increases in mean hemispheric Fg and brainstem-cerebellar Fg, just the opposite of changes in normals. In narcolepsy, there appears to be a reversal of normal cerebral deactivation patterns, particularly involving the brainstem, during stages I and II sleep.« less

Individualized follow up programme and early discharge in term neonates.

PubMed

De Carolis, Maria Pia; Cocca, Carmen; Valente, Elisabetta; Lacerenza, Serafina; Rubortone, Serena Antonia; Zuppa, Antonio Alberto; Romagnoli, Costantino

2014-07-15

Early discharge of mother/neonate dyad has become a common practice, and its effects are measured by readmission rates. We evaluated the safety of early discharge followed by an individualized Follow-up programme and the efficacy in promoting breastfeeding initiation and duration. During a nine-month period early discharge followed by an early targeted Follow-up was carried out in term neonates in the absence of weight loss <10% or hyperbilirubinaemia at risk of treatment. Follow-up visits were performed at different timepoints with a specific flow-chart according to both bilirubin levels and weight loss at discharge. During the study period early discharge was performed in 419 neonates and Follow-up was carried out in 408 neonates (97.4%). No neonates required readmission for hyperbilirubinaemia and dehydration during the first 28 days of life. Breastfeeding rate was 90.6%, 75.2%, 41.5% at 30, 90 and 180 days of life, respectively. A six-month phone interview was performed for 383 neonates (93.8%) and satisfaction of parents about early discharge was high in 345 cases (90.1%). Early discharge in association with an individualized Follow-up programme resulted safe for the neonate and effective for breastfeeding initation and duration.

Intermediate regime and a phase diagram of red blood cell dynamics in a linear flow.

PubMed

Levant, Michael; Steinberg, Victor

2016-12-01

In this paper we investigate the in vitro dynamics of a single rabbit red blood cell (RBC) in a planar linear flow as a function of a shear stress σ and the dynamic viscosity of outer fluid η_{o}. A linear flow is a generalization of previous studies dynamics of soft objects including RBC in shear flow and is realized in the experiment in a microfluidic four-roll mill device. We verify that the RBC stable orientation dynamics is found in the experiment being the in-shear-plane orientation and the RBC dynamics is characterized by observed three RBC dynamical states, namely tumbling (TU), intermediate (INT), and swinging (SW) [or tank-treading (TT)] on a single RBC. The main results of these studies are the following. (i) We completely characterize the RBC dynamical states and reconstruct their phase diagram in the case of the RBC in-shear-plane orientation in a planar linear flow and find it in a good agreement with that obtained in early experiments in a shear flow for human RBCs. (ii) The value of the critical shear stress σ_{c} of the TU-TT(SW) transition surprisingly coincides with that found in early experiments in spite of a significant difference in the degree of RBC shape deformations in both the SW and INT states. (iii) We describe the INT regime, which is stationary, characterized by strong RBC shape deformations and observed in a wide range of the shear stresses. We argue that our observations cast doubts on the main claim of the recent numerical simulations that the only RBC spheroidal stress-free shape is capable to explain the early experimental data. Finally, we suggest that the amplitude dependence of both θ and the shape deformation parameter D on σ can be used as the quantitative criterion to determine the RBC stress-free shape.

Physical mechanisms of longitudinal vortexes formation, appearance of zones with high heat fluxes and early transition in hypersonic flow over delta wing with blunted leading edges

NASA Astrophysics Data System (ADS)

Alexandrov, S. V.; Vaganov, A. V.; Shalaev, V. I.

2016-10-01

Processes of vortex structures formation and they interactions with the boundary layer in the hypersonic flow over delta wing with blunted leading edges are analyzed on the base of experimental investigations and numerical solutions of Navier-Stokes equations. Physical mechanisms of longitudinal vortexes formation, appearance of abnormal zones with high heat fluxes and early laminar turbulent transition are studied. These phenomena were observed in many high-speed wind tunnel experiments; however they were understood only using the detailed analysis of numerical modeling results with the high resolution. Presented results allowed explaining experimental phenomena. ANSYS CFX code (the DAFE MIPT license) on the grid with 50 million nodes was used for the numerical modeling. The numerical method was verified by comparison calculated heat flux distributions on the wing surface with experimental data.

Approximate analytical solution for non-Darcian flow toward a partially penetrating well in a confined aquifer

NASA Astrophysics Data System (ADS)

Wen, Zhang; Liu, Kai; Chen, Xiaolian

2013-08-01

In this study, non-Darcian flow to a partially penetrating well in a confined aquifer was investigated. The flow in the horizontal direction was assumed to be non-Darcian, while the flow in the vertical direction was assumed to be Darcian. The Izbash equation was employed to describe the non-Darcian flow in the horizontal direction of the aquifer. We used a linearization procedure to approximate the non-linear term in the governing equation enabling the mathematical model to be solved using a combination of Laplace and Fourier cosine transforms. Approximate analytical solutions for the drawdown were obtained and the impacts of different parameters on the drawdown were analyzed. The results indicated that a larger power index n in the Izbash equation leads to a larger drawdown at early times, while a larger n results in a smaller drawdown at late times. The drawdowns along the vertical direction z are symmetric if the well screen is located in the center of the aquifer, and the drawdown at the center of the aquifer is the largest along the vertical direction for this case. The length of the well screen w has little impact on the drawdown at early times, while a larger length of the well screen results in a smaller drawdown at late times. The drawdown increases with Kr at early times, while it decreases as Kr increases at late times, in which Kr is the apparent radial hydraulic conductivity. A sensitivity analysis of the parameters, i.e., the specific storage Ss, w, n and Kr, indicated that the drawdown is not sensitive to them at early times, while it is very sensitive to these parameters at late times especially to the power index n.

Hydrological and thermal effects of hydropeaking on early life stages of salmonids: A modelling approach for implementing mitigation strategies.

PubMed

Casas-Mulet, Roser; Saltveit, Svein Jakob; Alfredsen, Knut Tore

2016-12-15

Alterations in hydrological and thermal regimes can potentially affect salmonid early life stages development and survival. The dewatering of salmon spawning redds due to hydropeaking can lead to mortality in early life stages, with higher impact on the alevins as they have lower tolerance to dewatering than the eggs. Flow-related mitigation measures can reduce early life stage mortality. We present a set of modelling tools to assess impacts and mitigation options to minimise the risk of mortality in early life stages in hydropeaking rivers. We successfully modelled long-term hydrological and thermal alterations and consequences for development rates. We estimated the risk of early life stages mortality and assessed the cost-effectiveness of implementing three release-related mitigation options (A,B,C). The economic cost of mitigation was low and ranged between 0.7% and 2.6% of the annual hydropower production. Options reducing the flow during spawning (B and C) in addition to only release minimum flows during development (A) were considered more effective for egg and alevin survival. Options B and C were however constraint by water availability in the system for certain years, and therefore only option A was always feasible. The set of modelling tools used in this study were satisfactory and their applications can be useful especially in systems where little field data is available. Targeted measures built on well-informed modelling tools can be tested on their effectiveness to mitigate dewatering effects vs. the hydropower system capacity to release or conserve water for power production. Environmental flow releases targeting specific ecological objectives can provide better cost-effective options than conventional operational rules complying with general legislation. Copyright © 2016 Elsevier B.V. All rights reserved.

Control of the hierarchical assembly of π-conjugated optoelectronic peptides by pH and flow

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

Mansbach, Rachael A.; Ferguson, Andrew L.

Self-assembled nanoaggregates of p-conjugated peptides possess optoelectronic properties due to electron delocalization over the conjugated peptide groups that make them attractive candidates for the fabrication of bioelectronic materials. We present a computational and theoretical study to resolve the microscopic effects of pH and flow on the non-equilibrium morphology and kinetics of early-stage assembly of an experimentally-realizable optoelectronic peptide that displays pH triggerable assembly. Employing coarse-grained molecular dynamics simulations, we probe the effects of pH on growth kinetics and aggregate morphology to show that control of the peptide protonation state by pH can be used to modulate the assembly rates, degreemore » of molecular alignment, and resulting morphologies within the self-assembling nanoaggregates. We also quantify the time and length scales at which convective flows employed in directed assembly compete with microscopic diffusion to show that flow influences cluster alignment and assembly rate during early-stage assembly only at extremely high shear rates. This suggests that observed improvements in optoelectronic properties at experimentally-accessible shear rates are due to the alignment of large aggregates of hundreds of monomers on time scales in excess of hundreds of nanoseconds. Lastly, our work provides new fundamental understanding of the effects of pH and flow to control the morphology and kinetics of early-stage assembly of p-conjugated peptides and lays the groundwork for the rational manipulation of environmental conditions to direct assembly and the attendant emergent optoelectronic properties.« less

Control of the hierarchical assembly of π-conjugated optoelectronic peptides by pH and flow

DOE PAGES

Mansbach, Rachael A.; Ferguson, Andrew L.

2017-01-01

Self-assembled nanoaggregates of p-conjugated peptides possess optoelectronic properties due to electron delocalization over the conjugated peptide groups that make them attractive candidates for the fabrication of bioelectronic materials. We present a computational and theoretical study to resolve the microscopic effects of pH and flow on the non-equilibrium morphology and kinetics of early-stage assembly of an experimentally-realizable optoelectronic peptide that displays pH triggerable assembly. Employing coarse-grained molecular dynamics simulations, we probe the effects of pH on growth kinetics and aggregate morphology to show that control of the peptide protonation state by pH can be used to modulate the assembly rates, degreemore » of molecular alignment, and resulting morphologies within the self-assembling nanoaggregates. We also quantify the time and length scales at which convective flows employed in directed assembly compete with microscopic diffusion to show that flow influences cluster alignment and assembly rate during early-stage assembly only at extremely high shear rates. This suggests that observed improvements in optoelectronic properties at experimentally-accessible shear rates are due to the alignment of large aggregates of hundreds of monomers on time scales in excess of hundreds of nanoseconds. Lastly, our work provides new fundamental understanding of the effects of pH and flow to control the morphology and kinetics of early-stage assembly of p-conjugated peptides and lays the groundwork for the rational manipulation of environmental conditions to direct assembly and the attendant emergent optoelectronic properties.« less

Irrigated mountain meadow fertilizer application timing effects on overland flow water quality.

PubMed

White, Shawn K; Brummer, Joe E; Leininger, Wayne C; Frasier, Gary W; Waskom, Reagan M; Bauder, Troy A

2003-01-01

Nonpoint-source pollution from agricultural activities is currently the leading cause of degradation of waterways in the United States. Applying best management practices to flood-irrigated mountain meadows may improve agricultural runoff and return flow water quality. Prior research has focused on fertilizer use for increased hay yields, while few studies have investigated the environmental implications of this practice. We examined the effects of fertilizer application timing on overland flow water quality from an irrigated mountain meadow near Gunnison, Colorado. Application of 40 kg phosphorus (P) and 19 kg nitrogen (N) ha(-1) using monoammonium phosphate (11-52-0, N-P-K) fertilizer to plots in the fall significantly reduced concentrations of reactive P and ammonium N in irrigation overland flow compared with early or late spring fertilization. Reactive P loading was 9 to almost 16 times greater when fertilizer was applied in the early or late spring, respectively, compared with in the fall. Ammonium N followed a similar trend with early spring loading more than 18 times greater and late spring loading more than 34 times greater than loads from fall-fertilized plots. Losses of 45% of the applied P and more than 17% of the N were measured in runoff when fertilizer was applied in the late spring. These results, coupled with those from previous studies, suggest that mountain meadow hay producers should apply fertilizer in the fall, especially P-based fertilizers, to improve hay yields, avoid economic losses from loss of applied fertilizers, and reduce the potential for impacts to water quality.

Fire, Lava Flows, and Human Evolution

NASA Astrophysics Data System (ADS)

Medler, M. J.

2015-12-01

Richard Wrangham and others argue that cooked food has been obligate for our ancestors since the time of Homo erectus. This hypothesis provides a particularly compelling explanation for the smaller mouths and teeth, shorter intestines, and larger brains that separate us from other hominins. However, natural ignitions are infrequent and it is unclear how earlier hominins may have adapted to cooked food and fire before they developed the necessary intelligence to make or control fire. To address this conundrum, we present cartographical evidence that the massive and long lasting lava flows in the African Rift could have provided our ancestors with episodic access to heat and fire as the front edges of these flows formed ephemeral pockets of heat and ignition and other geothermal features. For the last several million years major lava flows have been infilling the African Rift. After major eruptions there were likely more slowly advancing lava fronts creating small areas with very specific adaptive pressures and opportunities for small isolated groups of hominins. Some of these episodes of isolation may have extended for millennia allowing these groups of early hominins to develop the adaptations Wrangham links to fire and cooked food. To examine the potential veracity of this proposal, we developed a series of maps that overlay the locations of prominent hominin dig sites with contemporaneous lava flows. These maps indicate that many important developments in hominin evolution were occurring in rough spatial and temporal proximity to active lava flows. These maps indicate it is worth considering that over the last several million years small isolated populations of hominins may have experienced unique adaptive conditions while living near the front edges of these slowly advancing lava flows.

Early history of Neanderthals and Denisovans

PubMed Central

Bohlender, Ryan J.; Huff, Chad D.

2017-01-01

Extensive DNA sequence data have made it possible to reconstruct human evolutionary history in unprecedented detail. We introduce a method to study the past several hundred thousand years. Our results show that (i) the Neanderthal–Denisovan lineage declined to a small size just after separating from the modern lineage, (ii) Neanderthals and Denisovans separated soon thereafter, and (iii) the subsequent Neanderthal population was large and deeply subdivided. They also (iv) support previous estimates of gene flow from Neanderthals into modern Eurasians. These results suggest an archaic human diaspora early in the Middle Pleistocene. PMID:28784789

Sedimentary history and mass flow structures of Chryse and Acidalia Planitiae, Mars

USGS Publications Warehouse

Tanaka, K.L.

1997-01-01

Geologic mapping and crater counting in Chryse and Acidalia Planitiae (GAP) reveal five major sedimentary deposits of Hesperian to Early Amazonian age, including (1) a mass flow deposited during the Early Hesperian near Deuteronilus Mensae (northeast of the map region) that may have resulted from the carving of Kasei Valles, >3000 km southwest of the exposed part of the deposit; (2) knobby plains material consisting of channel (likely; from Simud and Tiu Valles and possibly Ares and Shalbatana Valles) and mass-wasting deposits in central and eastern CAP; (3) material largely from Maja and Ares Valles emplaced in at least western and southern CAP (outcrops in southern Chryse Planitia developed thermokarst); (4) a thin mass flow covering much of southern Chryse Planitia that emanated from Simud and Tiu Valles; and (5) a thick, extensive (perhaps >3500 km across) mass flow deposit in central and northern CAP derived from accumulation and backflow of the preceding thin mass flow or perhaps melting of polar deposits. Other possible deposits may not be recognizable owing to burial by younger materials or a lack of morphologic signature. Various associated landforms appear to be consistent with the mass flow interpretations, including lobate and linear scarps along deposit edges, fractures related to desiccation of thick sediments, troughs, and ridges near the edges of the deposit indicative of secondary mass movement and deformation, pitted domes and fissure-fed flows possibly formed by sedimentary (mud) eruptions, and longitudinal channel grooves perhaps formed by roller vortices. No convincing evidence for paleoshorelines or stagnant ice sheets is found in CAP. These findings suggest that mass flow and hyperconcentrated flooding may have been the predominant processes of outflow-channel dissection in CAP. Elsewhere in the northern plains, similar landforms are prevalent. The mass flow interpretation does not require either multiple episodes of extraordinarily high

Effects of stream flow intermittency on riparian vegetation of a semiarid region river (San Pedro River, Arizona)

USGS Publications Warehouse

Stromberg, J.C.; Bagstad, K.J.; Leenhouts, J.M.; Lite, S.J.; Makings, E.

2005-01-01

The San Pedro River in the southwestern United States retains a natural flood regime and has several reaches with perennial stream flow and shallow ground water. However, much of the river flows intermittently. Urbanization-linked declines in regional ground-water levels have raised concerns over the future status of the riverine ecosystem in some parts of the river, while restoration-linked decreases in agricultural ground-water pumping are expected to increase stream flows in other parts. This study describes the response of the streamside herbaceous vegetation to changes in stream flow permanence. During the early summer dry season, streamside herbaceous cover and species richness declined continuously across spatial gradients of flow permanence, and composition shifted from hydric to mesic species at sites with more intermittent flow. Hydrologic threshold values were evident for one plant functional group: Schoenoplectus acutus, Juncus torreyi, and other hydric riparian plants declined sharply in cover with loss of perennial stream flow. In contrast, cover of mesic riparian perennials (including Cynodon dactylon, an introduced species) increased at sites with intermittent flow. Patterns of hydric and mesic riparian annuals varied by season: in the early summer dry season their cover declined continuously as flow became more intermittent, while in the late summer wet season their cover increased as the flow became more intermittent. Periodic drought at the intermittent sites may increase opportunities for establishment of these annuals during the monsoonal flood season. During the late summer flood season, stream flow was present at most sites, and fewer vegetation traits were correlated with flow permanence; cover and richness were correlated with other environmental factors including site elevation and substrate nitrate level and particle size. Although perennial-flow and intermittent-flow sites support different streamside plant communities, all of the plant

Assessment and monitoring of flow limitation and other parameters from flow/volume loops.

PubMed

Dueck, R

2000-01-01

Flow/volume (F/V) spirometry is routinely used for assessing the type and severity of lung disease. Forced vital capacity (FVC) and timed vital capacity (FEV1) provide the best estimates of airflow obstruction in patients with asthma, chronic obstructive pulmonary disease (COPD) and emphysema. Computerized spirometers are now available for early home recognition of asthma exacerbation in high risk patients with severe persistent disease, and for recognition of either infection or rejection in lung transplant patients. Patients with severe COPD may exhibit expiratory flow limitation (EFL) on tidal volume (VT) expiratory F/V (VTF/V) curves, either with or without applying negative expiratory pressure (NEP). EFL results in dynamic hyperinflation and persistently raised alveolar pressure or intrinsic PEEP (PEEPi). Hyperinflation and raised PEEPi greatly enhance dyspnea with exertion through the added work of the threshold load needed to overcome raised pleural pressure. Esophageal (pleural) pressure monitoring may be added to VTF/V loops for assessing the severity of PEEPi: 1) to optimize assisted ventilation by mask or via endotracheal tube with high inspiratory flow rates to lower I:E ratio, and 2) to assess the efficacy of either pressure support ventilation (PSV) or low level extrinsic PEEP in reducing the threshold load of PEEPi. Intraoperative tidal volume F/V loops can also be used to document the efficacy of emphysema lung volume reduction surgery (LVRS) via disappearance of EFL. Finally, the mechanism of ventilatory constraint can be identified with the use of exercise tidal volume F/V loops referenced to maximum F/V loops and static lung volumes. Patients with severe COPD show inspiratory F/V loops approaching 95% of total lung capacity, and flow limitation over the entire expiratory F/V curve during light levels of exercise. Surprisingly, patients with a history of congestive heart failure may lower lung volume towards residual volume during exercise

Instruments and Methods for Measuring the Flow of Water Around Ships and Ship Models

DTIC Science & Technology

1948-03-01

velocity of flow, the direction of flow, and the speed of a ship are based on the pitot tube design- ed by Henri Pitot , a French physicist and engineer of...INTRODUCTION . .’ 1 DEVELOPMENT OP EARLY INSTRUMENTS . 2 PITOT -STATIC TUBE 2 SPEED LOOS k INSTRUMENT.- USED BY THE TAYLOR MODEL BASIN...5 CYLINDRICAL PITOT TUBE 5 SPHERICAL PITOT TUBE 10 ROTATING WAKE METER 1? BOW LOO 19 INSTRUMENTS USED BY OTHER MODEL BASINS 21

A new lumped-parameter model for flow in unsaturated dual-porosity media

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

Zimmerman, Robert W.; Hadgu, Teklu; Bodvarsson, Gudmundur S.

A new lumped-parameter approach to simulating unsaturated flow processes in dual-porosity media such as fractured rocks or aggregated soils is presented. Fluid flow between the fracture network and the matrix blocks is described by a non-linear equation that relates the imbibition rate to the local difference in liquid-phase pressure between the fractures and the matrix blocks. Unlike a Warren-Root-type equation, this equation is accurate in both the early and late time regimes. The fracture/matrix interflow equation has been incorporated into an existing unsaturated flow simulator, to serve as a source/sink term for fracture gridblocks. Flow processes are then simulated usingmore » only fracture gridblocks in the computational grid. This new lumped-parameter approach has been tested on two problems involving transient flow in fractured/porous media, and compared with simulations performed using explicit discretization of the matrix blocks. The new procedure seems to accurately simulate flow processes in unsaturated fractured rocks, and typically requires an order of magnitude less computational time than do simulations using fully-discretized matrix blocks. [References: 37]« less

Governance, Accountability and the Datafication of Early Years Education in England

ERIC Educational Resources Information Center

Roberts-Holmes, Guy; Bradbury, Alice

2016-01-01

In this paper we attempt to critically "make visible the flow and circulation of data" through analysing the datafication of the early years education sector in England (children aged 2-5). The concept of datafication is used to understand the processes and impacts of burgeoning data-based governance and accountability regimes. This…

Conditions on Early Mars Might Have Fostered Rapid and Early Development of Life

NASA Technical Reports Server (NTRS)

Gibson, Everett K.; McKay, David S.; Thomas-Keprta, Kathie L.; Clemett, Simon J.; Wentworth, Susan J.

2007-01-01

The exploration of Mars during the past decades has begun to unveil the history of the planet. The combinations of remote sensing, in situ geochemical compositional measurements and photographic observations from both above and on the surface have shown Mars to have a dynamic and active geologic evolution. Mars geologic evolution clearly had conditions that were suitable for supporting life. For a planet to be able to be habitable, it must have water, carbon sources, energy sources and a dynamic geologic past. Mars meets all of these requirements. The first 600 My of Martian history were ripe for life to develop because of the abundance of (i) Water-carved canyons and oceans or lakes with the early presence of near surface water shown by precipitated carbonates in ALH84001 well-dated at approx.3.9 Gy., (ii) Energy from the original accretional processes, a molten core which generated a strong magnetic field leaving a permanent record in the early crust, early active volcanism continuing throughout Martian history, and, and continuing impact processes, (iii) Carbon and water from possibly extensive volcanic outgassing (i.e. H2O, CO2, CH4, CO, O2, N2, H2S, SO2, etc.) and (iv) some crustal tectonics as revealed by faulting and possible plate movement reflected by the magnetic pattern in the crust. The question arises: "Why would life not evolve from these favorable conditions on early Mars in its first 600 My?" During this period, it seems likely that environmental near-surface conditions on Mars were more favorable to life than at any later time. Standing bodies of water, precipitation and flowing surface water, and possibly abundant hydrothermal energy would all favor the formation of early life. Even if life developed elsewhere (on Earth, Venus, or on other solar systems) and was transported to Mars, the surface conditions were likely very hospitable for that introduced life to multiply and evolve.

Debris flows susceptibility mapping under tropical rain conditions in Rwanda.

NASA Astrophysics Data System (ADS)

Nduwayezu, Emmanuel; Nsengiyumva, Jean-Baptiste; BUgnon, Pierre-Charles; Jaboyedoff, Michel; Derron, Marc-Henri

2017-04-01

Rwanda is a densely populated country. It means that all the space is exploited, including sometimes areas with very steep slopes. This has as for consequences that during the rainy season slopes with human activities are affected by gravitational processes, mostly debris and mud flows and shallow landslides. The events of early May 2016 (May 8 and 9), with more than 50 deaths, are an illustration of these frequents landslides and inundations. The goal of this work is to produce a susceptibility map for debris/mud flows at regional/national scale. Main available pieces of data are a national digital terrain model at 10m resolution, bedrock and soil maps, and information collected during field visits on some specific localities. The first step is the characterization of the slope angle distribution for the different types of bedrock or soils (decomposition in Gaussian populations). Then, the combination of this information with other geomorphic and hydrologic parameters is used to define potential source areas of debris flows. Finally, propagation maps of debris flows are produced using FLOW-R (Horton et al. 2013). Horton, P., Jaboyedoff, M., Rudaz, B., and Zimmermann, M.: Flow-R, a model for susceptibility mapping of debris flows and other gravitational hazards at a regional scale, Nat. Hazards Earth Syst. Sci., 13, 869-885, doi:10.5194/nhess-13-869-2013, 2013. The paper is in open access.

Lithospheric strength of Ganymede: Clues to early thermal profiles from extensional tectonic features

NASA Technical Reports Server (NTRS)

Golombek, M. P.; Banerdt, W. B.

1985-01-01

While it is generally agreed that the strength of a planet's lithosphere is controlled by a combination of brittle sliding and ductile flow laws, predicting the geometry and initial characteristics of faults due to failure from stresses imposed on the lithospheric strength envelope has not been thoroughly explored. Researchers used lithospheric strength envelopes to analyze the extensional features found on Ganymede. This application provides a quantitative means of estimating early thermal profiles on Ganymede, thereby constraining its early thermal evolution.

Mitral valve resistance determines hemodynamic consequences of severe rheumatic mitral stenosis and immediate outcomes of percutaneous valvuloplasty.

PubMed

Sanati, Hamidreza; Zolfaghari, Reza; Samiei, Niloufar; Rezaei, Yousef; Chitsazan, Mitra; Zahedmehr, Ali; Shakerian, Farshad; Kiani, Reza; Firouzi, Ata; Rezaei Tabrizi, Reza

2017-02-01

The mitral valve area (MVA) poorly reflects the hemodynamic status of (MS). In this study, we compared the MVA with mitral valve resistance (MVR) with regard to the determination of hemodynamic consequences of MS and the immediate outcomes of percutaneous balloon mitral valvuloplasty (PBMV). In a prospective study, 36 patients with severe rheumatic MS with left ventricular ejection fraction (LVEF) >50% were evaluated. They underwent transthoracic echocardiography (TTE) and catheterization. The MVA was measured by two-dimensional planimetry and pressure half-time (PHT), and the MVR was calculated using the equation: 1333 × transmitral pressure gradient mean transmitral diastolic flow rate. The patients' mean age was 47.8±10.5 years. MVR ≥140.6 dynes·s/cm 5 detected systolic pulmonary arterial pressure (sPAP) >55 mm Hg with a sensitivity of 100% and a specificity of 74%. The sensitivity and specificity of MVA<0.75 cm 2 to discriminate elevated sPAP were 81% and 89%, respectively. PHT ≥323.5 mseconds had a sensitivity of 78% and a specificity of 96% to detect an elevated sPAP. To predict a successful PBMV, preprocedural MVR ≥106.1 dynes·s/cm 5 had a sensitivity of 100% and a specificity of 67% (area under the curve [AUC]=0.763; 95% confidence interval [CI]=0.520-1.006; P=.034); preprocedural MVA <0.95 cm 2 had a sensitivity of 78% and a specificity of 73% (AUC=0.730; 95% CI=0.503-0.956; P=.065); and preprocedural PHT ≥210.5 mseconds had a sensitivity of 73% and a specificity of 78% (AUC=0.707; 95% CI=0.474-0.941; P=.095). MVR seems to be more accurate than MVA in determining the hemodynamic consequences of severe MS as determined by sPAP. In addition, preprocedural MVR detected successful PBMVs. © 2017, Wiley Periodicals, Inc.

Early predictors of unresponsiveness to high-flow nasal cannula therapy in a pediatric emergency department.

PubMed

Er, Anıl; Çağlar, Aykut; Akgül, Fatma; Ulusoy, Emel; Çitlenbik, Hale; Yılmaz, Durgül; Duman, Murat

2018-06-01

High-flow nasal cannula (HFNC) is a new treatment option for pediatric respiratory distress and we aimed to assess early predictive factors of unresponsiveness to HFNC therapy in a pediatric emergency department (ED). Patients who presented with respiratory distress and were treated by HFNC, were included. The age, gender, weight, medical history, diagnosis, vital signs, oxygen saturation/fraction of inspired oxygen (SpO 2 /FiO 2 ) ratio, modified Respiratory Distress Assessment Instrument (mRDAI) scores, medical interventions, duration of HFNC therapy, time to escalation, adverse effects, and laboratory test results were obtained from medical and nursing records. The requirement of a higher level of respiratory support due to unchanged or increased RR compared to initial RR, incipient, or progressive respiratory acidosis, incipient hemodynamic instability was defined as unresponsiveness to HFNC. The study enrolled 154 children with a median age of 10 months (interquartile range [IQR], 5.7-22.5 months). The diagnosis was acute bronchiolitis in 59 patients (38.3%), bacterial pneumonia in 64 patients (41.6%), and atypical or viral pneumonia in 31 patients (20.1%). Twenty-five patients (16.2%) were in the unresponsive group, and the median time for escalating respiratory support was 7 h (IQR: 4-20 h). The unresponsive group had lower SpO 2 and SpO 2 /FiO 2 (SF) ratio on admission, lower venous pH, and higher partial pressure of carbon dioxide (pCO 2 ) (P = 0.002, P = 0.012, and P = 0.001, respectively). Also the alteration of RR, mRDAI score, and SF ratio at the first hour was greater in the responsive group. The cut-off value of SF ratio at the first hour of HFNC was 195 for unresponsiveness. The low initial SpO 2 and SF ratio, respiratory acidosis, and SF ratio less than 195 at the first hours of treatment were related to unresponsiveness to HFNC therapy in our pediatric emergency department. © 2018 Wiley Periodicals, Inc.

Anthropogenic Habitats Facilitate Dispersal of an Early Successional Obligate: Implications for Restoration of an Endangered Ecosystem.

PubMed

Amaral, Katrina E; Palace, Michael; O'Brien, Kathleen M; Fenderson, Lindsey E; Kovach, Adrienne I

2016-01-01

Landscape modification and habitat fragmentation disrupt the connectivity of natural landscapes, with major consequences for biodiversity. Species that require patchily distributed habitats, such as those that specialize on early successional ecosystems, must disperse through a landscape matrix with unsuitable habitat types. We evaluated landscape effects on dispersal of an early successional obligate, the New England cottontail (Sylvilagus transitionalis). Using a landscape genetics approach, we identified barriers and facilitators of gene flow and connectivity corridors for a population of cottontails in the northeastern United States. We modeled dispersal in relation to landscape structure and composition and tested hypotheses about the influence of habitat fragmentation on gene flow. Anthropogenic and natural shrubland habitats facilitated gene flow, while the remainder of the matrix, particularly development and forest, impeded gene flow. The relative influence of matrix habitats differed between study areas in relation to a fragmentation gradient. Barrier features had higher explanatory power in the more fragmented site, while facilitating features were important in the less fragmented site. Landscape models that included a simultaneous barrier and facilitating effect of roads had higher explanatory power than models that considered either effect separately, supporting the hypothesis that roads act as both barriers and facilitators at all spatial scales. The inclusion of LiDAR-identified shrubland habitat improved the fit of our facilitator models. Corridor analyses using circuit and least cost path approaches revealed the importance of anthropogenic, linear features for restoring connectivity between the study areas. In fragmented landscapes, human-modified habitats may enhance functional connectivity by providing suitable dispersal conduits for early successional specialists.

Anthropogenic Habitats Facilitate Dispersal of an Early Successional Obligate: Implications for Restoration of an Endangered Ecosystem

PubMed Central

Amaral, Katrina E.; Palace, Michael; O’Brien, Kathleen M.; Fenderson, Lindsey E.; Kovach, Adrienne I.

2016-01-01

Landscape modification and habitat fragmentation disrupt the connectivity of natural landscapes, with major consequences for biodiversity. Species that require patchily distributed habitats, such as those that specialize on early successional ecosystems, must disperse through a landscape matrix with unsuitable habitat types. We evaluated landscape effects on dispersal of an early successional obligate, the New England cottontail (Sylvilagus transitionalis). Using a landscape genetics approach, we identified barriers and facilitators of gene flow and connectivity corridors for a population of cottontails in the northeastern United States. We modeled dispersal in relation to landscape structure and composition and tested hypotheses about the influence of habitat fragmentation on gene flow. Anthropogenic and natural shrubland habitats facilitated gene flow, while the remainder of the matrix, particularly development and forest, impeded gene flow. The relative influence of matrix habitats differed between study areas in relation to a fragmentation gradient. Barrier features had higher explanatory power in the more fragmented site, while facilitating features were important in the less fragmented site. Landscape models that included a simultaneous barrier and facilitating effect of roads had higher explanatory power than models that considered either effect separately, supporting the hypothesis that roads act as both barriers and facilitators at all spatial scales. The inclusion of LiDAR-identified shrubland habitat improved the fit of our facilitator models. Corridor analyses using circuit and least cost path approaches revealed the importance of anthropogenic, linear features for restoring connectivity between the study areas. In fragmented landscapes, human-modified habitats may enhance functional connectivity by providing suitable dispersal conduits for early successional specialists. PMID:26954014

Warming early Mars with carbon dioxide clouds that scatter infrared radiation.

PubMed

Forget, F; Pierrehumbert, R T

1997-11-14

Geomorphic evidence that Mars was warm enough to support flowing water about 3.8 billion years ago presents a continuing enigma that cannot be explained by conventional greenhouse warming mechanisms. Model calculations show that the surface of early Mars could have been warmed through a scattering variant of the greenhouse effect, resulting from the ability of the carbon dioxide ice clouds to reflect the outgoing thermal radiation back to the surface. This process could also explain how Earth avoided an early irreversible glaciation and could extend the size of the habitable zone on extrasolar planets around stars.

Flow regimes and mechanistic modeling of critical heat flux under subcooled flow boiling conditions

NASA Astrophysics Data System (ADS)

Le Corre, Jean-Marie

Thermal performance of heat flux controlled boiling heat exchangers are usually limited by the Critical Heat Flux (CHF) above which the heat transfer degrades quickly, possibly leading to heater overheating and destruction. In an effort to better understand the phenomena, a literature review of CHF experimental visualizations under subcooled flow boiling conditions was performed and systematically analyzed. Three major types of CHF flow regimes were identified (bubbly, vapor clot and slug flow regime) and a CHF flow regime map was developed, based on a dimensional analysis of the phenomena and available data. It was found that for similar geometric characteristics and pressure, a Weber number (We)/thermodynamic quality (x) map can be used to predict the CHF flow regime. Based on the experimental observations and the review of the available CHF mechanistic models under subcooled flow boiling conditions, hypothetical CHF mechanisms were selected for each CHF flow regime, all based on a concept of wall dry spot overheating, rewetting prevention and subsequent dry spot spreading. It is postulated that a high local wall superheat occurs locally in a dry area of the heated wall, due to a cyclical event inherent to the considered CHF two-phase flow regime, preventing rewetting (Leidenfrost effect). The selected modeling concept has the potential to span the CHF conditions from highly subcooled bubbly flow to early stage of annular flow. A numerical model using a two-dimensional transient thermal analysis of the heater undergoing nucleation was developed to mechanistically predict CHF in the case of a bubbly flow regime. In this type of CHF two-phase flow regime, the high local wall superheat occurs underneath a nucleating bubble at the time of bubble departure. The model simulates the spatial and temporal heater temperature variations during nucleation at the wall, accounting for the stochastic nature of the boiling phenomena. The model has also the potential to evaluate

Electrochemistry of Prebiotic Early Earth Hydrothermal Chimney Systems

NASA Astrophysics Data System (ADS)

Hermis, N.; Barge, L. M.; Chin, K. B.; LeBlanc, G.; Cameron, R.

2017-12-01

Hydrothermal chimneys are self-organizing chemical garden precipitates generated from geochemical disequilibria within sea-vent environments, and have been proposed as a possible setting for the emergence of life because they contain mineral catalysts and transect ambient pH / Eh / chemical gradients [1]. We simulated the growth of hydrothermal chimneys in early Earth vent systems by using different hydrothermal simulants such as sodium sulfide (optionally doped with organic molecules) which were injected into an early Earth ocean simulant containing dissolved ferrous iron, nickel, and bicarbonate [2]. Chimneys on the early Earth would have constituted flow-through reactors, likely containing Fe/Ni-sulfide catalysts that could have driven proto-metabolic electrochemical reactions. The electrochemical activity of the chimney system was characterized non-invasively by placing electrodes at different locations across the chimney wall and in the ocean to analyze the bulk properties of surface charge potential in the chimney / ocean / hydrothermal fluid system. We performed in-situ characterization of the chimney using electrochemical impedance spectroscopy (EIS) which allowed us to observe the changes in physio-chemical behavior of the system through electrical spectra of capacitance and impedance over a wide range of frequencies during the metal sulfide chimney growth. The electrochemical properties of hydrothermal chimneys in natural systems persist due to the disequilibria maintained between the ocean and hydrothermal fluid. When the injection in our experiment (analogous to fluid flow in a vent) stopped, we observed a corresponding decline in open circuit voltage across the chimney wall, though the impedance of the precipitate remained lor. Further work is needed to characterize the electrochemistry of simulated chimney systems by controlling response factors such as electrode geometry and environmental conditions, in order to simulate electrochemical reactions

Influence of Dai-kenchu-to (DKT) on human portal blood flow.

PubMed

Ogasawara, Takashi; Morine, Yuji; Ikemoto, Tetsuya; Imura, Satoru; Fujii, Masahiko; Soejima, Yuji; Shimada, Mitsuo

2008-01-01

Dai-kenchu-to (DKT) is known as an herbal medicine used for postoperative ileus. However, no report exists about the effect of DKT on portal blood flow. The aim of this study is to clarify the influence of DKT on portal blood flow. To healthy volunteers (Healthy; n = 6), cirrhotic patients (Cirrhosis; n = 7) and liver-transplant patients (LTx; n = 3), DKT (2.5g) with 100mL of warm water was orally administrated in the DKT group, and only warm water was administrated in the control group. The portal blood flow rate (M-VEL: cm/sec.) and portal blood flow (Flow volume: mL/min.) was measured each time after administration using an ultrasonic Doppler method. Furthermore, the arterial blood pressure and heart rate was measured at the same time points. In the DKT group, a significant increase of M-VEL (120%) and flow volume (150%) 30 minutes after administration was observed in both Healthy and Cirrhosis in comparison with the control group. In LTx, there was also a significant increase of flow volume (128%) 30 minutes after administration. However, there was no change in average blood pressure and heart rate in all groups. DKT increases portal blood flow in early phase after oral administration without any significant changes in the blood pressure and heart rate.

Development and Testing of the Europa Mission's Venturi Flow Meter

NASA Technical Reports Server (NTRS)

Diaz, C. E.; McKim, S. A.

2017-01-01

NASA's Marshall Space Flight Center (MSFC), in collaboration with NASA's Goddard Space Flight Center (GSFC), Fox Valve Development Corp. and Oxford Lasers, is developing a set of venturi flow meters for use on the Europa Mission's propulsion subsystem. The requirement for the venturi flow meters' throat diameters is approximately 0.040". An early risk reduction activity conducted by MSFC revealed that a venturi flow meter produced by FOX with a throat diameter near 0.040" had much higher pressure loss than venturi flow meters with larger throat diameters and venturis of similar throat diameter size but with no pressure taps (i.e. venturis with a throat length to diameter ratio of zero). In response, a series of venturi flow meters was fabricated and flow tested to gain insight into pressure recovery as it is affected by pressure port diameter, throat length and diffuser angle in an effort to improve the performance of a venturi flow meter. This presentation provides a summary of the venturi flow meter development activity including: a description of the test's objectives, a detailed description of each venturi configuration, a description of the manufacturing processes of the venturis, and observations from the test data. A summary of the current development activities will also be given, as well as the current development path forward. Ultimately, the knowledge gained through the fabrication and testing of these venturis provides guidance to design a flight venturi flow meters with pressure recoveries that is acceptable for the Europa flight application.

Early and mid-term results in the endovascular treatment of popliteal aneurysms with the multilayer flow modulator.

PubMed

Ucci, Alessandro; Curci, Ruggiero; Azzarone, Matteo; Bianchini Massoni, Claudio; Bozzani, Antonio; Marcato, Carla; Marone, Enrico Maria; Perini, Paolo; Tecchio, Tiziano; Freyrie, Antonio; Argenteri, Angelo

2018-01-01

Background The endovascular approach became an alternative to open surgical treatment of popliteal artery aneurysm over the last few years. Heparin-bonded stent-grafts have been employed for endovascular popliteal artery aneurysm repair, showing good and stable results. Only few reports about the use of multilayer flow modulator are available in literature, providing small patient series and short follow-up. The aim of this study is to report the outcomes of patients with popliteal artery aneurysm treated with the multilayer flow modulator in three Italian centres. Methods We retrospectively analysed a series of both symptomatic and asymptomatic patients with popliteal artery aneurysm treated with the multilayer flow modulator from 2009 to 2015. Follow-up was undertaken with clinical and contrast-enhanced ultrasound examinations at 1, 6 and 12 months, and yearly thereafter. Computed tomography angiography was performed in selected cases. Primary endpoints were aneurysm sac thrombosis; freedom from sac enlargement and primary, primary-assisted and secondary patency during follow-up. Secondary endpoints were technical success, collateral vessels patency, limb salvage and aneurysm-related complications. Results Twenty-three consecutive patients (19 males, age 72 ± 11) with 25 popliteal artery aneurysms (mean diameter 23 mm ± 1, 3 symptomatic patients) were treated with 40 multilayer flow modulators during the period of the study. Median follow-up was 22.6 ± 16.7 months. Complete aneurysm thrombosis occurred in 92.9% of cases (23/25 cases) at 18 months. Freedom from sac enlargement was 100% (25/25 cases) with 17 cases of aneurysm sac shrinkage (68%). At 1, 6, 12 and 24 months, estimated primary patency was 95.7%, 87.3%, 77% and 70.1%, respectively. At the same intervals, primary-assisted patency was 95.7%, 91.3%, 86% and 86%, respectively, and secondary patency was 100%, 95.7%, 90.3% and 90.3%, respectively. Technical success was 100%. The collateral

Basal melting of snow on early Mars: A possible origin of some valley networks

USGS Publications Warehouse

Carr, M.H.; Head, J. W.

2003-01-01

Valley networks appear to be cut by liquid water, yet simulations suggest that early Mars could not have been warmed enough by a CO2-H2O greenhouse to permit rainfall. The vulnerability of an early atmosphere to impact erosion, the likely rapid scavenging of CO2 from the atmosphere by weathering, and the lack of detection of weathering products all support a cold early Mars. We explore the hypothesis that valley networks could have formed as a result of basal melting of thick snow and ice deposits. Depending on the heat flow, an early snowpack a few hundred meters to a few kilometers thick could undergo basal melting, providing water to cut valley networks. Copyright 2003 by the American Geophysical Union.

A probabilistic model for the persistence of early planar fabrics in polydeformed pelitic schists

USGS Publications Warehouse

Ferguson, C.C.

1984-01-01

Although early planar fabrics are commonly preserved within microlithons in low-grade pelites, in higher-grade (amphibolite facies) pelitic schists fabric regeneration often appears complete. Evidence for early fabrics may be preserved within porphyroblasts but, within the matrix, later deformation often appears to totally obliterate or reorient earlier fabrics. However, examination of several hundred Dalradian pelites from Connemara, western Ireland, reveals that preservation of early fabrics is by no means uncommon; relict matrix domains, although volumetrically insignificant, are remarkably persistent even when inferred later strains are very large and fabric regeneration appears, at first sight, complete. Deterministic plasticity theories are ill-suited to the analysis of such an inhomogeneous material response, and a probabilistic model is proposed instead. It assumes that ductile polycrystal deformation is controlled by elementary flow units which can be activated once their associated stress barrier is overcome. Bulk flow propensity is related to the proportion of simultaneous activations, and a measure of this is derived from the probabilistic interaction between a stress-barrier spectrum and an internal stress spectrum (the latter determined by the external loading and the details of internal stress transfer). The spectra are modelled as Gaussian distributions although the treatment is very general and could be adapted for other distributions. Using the time rate of change of activation probability it is predicted that, initially, fabric development will be rapid but will then slow down dramatically even though stress increases at a constant rate. This highly non-linear response suggests that early fabrics persist because they comprise unfavourable distributions of stress-barriers which remain unregenerated at the time bulk stress is stabilized by steady-state flow. Relict domains will, however, bear the highest stress and are potential upper

Status of systemic to pulmonary arterial collateral flow after the fontan procedure.

PubMed

Whitehead, Kevin K; Harris, Matthew A; Glatz, Andrew C; Gillespie, Matthew J; DiMaria, Michael V; Harrison, Neil E; Dori, Yoav; Keller, Marc S; Rome, Jonathan J; Fogel, Mark A

2015-06-15

The investigators recently validated a method of quantifying systemic-to-pulmonary arterial collateral flow using phase-contrast magnetic resonance imaging velocity mapping. Cross-sectional data suggest decreased collateral flow in patients with total cavopulmonary connections (TCPCs) compared with those with superior cavopulmonary connections (SCPCs). However, no studies have examined serial changes in collateral flow from SCPCs to TCPCs in the same patients. The aim of this study was to examine differences in collateral flow between patients with SCPCs and those with TCPCs. Collateral flow was quantified by 2 independent measures from 250 single-ventricle studies in 219 different patients (115 SCPC and 135 TCPC studies, 31 patients with both) and 18 controls, during routine studies using through-plane phase-contrast magnetic resonance imaging. Collateral flow was indexed to body surface area, aortic flow, and pulmonary venous flow. Regardless of indexing method, SCPC patients had significantly higher collateral flow than TCPC patients (1.64 ± 0.8 vs 1.03 ± 0.8 L/min/m(2), p <0.001). In 31 patients who underwent serial examinations, collateral flow as a fraction of aortic flow increased early after TCPC completion. In TCPC patients, indexed collateral flow demonstrated a significant negative correlation with time from TCPC. In conclusion, SCPC and TCPC patients demonstrate substantial collateral flow, with SCPC patients having higher collateral flow than TCPC patients overall. On the basis of the paired subset analysis, collateral flow does not decrease in the short term after TCPC completion and trends toward an increase. In the long term, however, collateral flow decreases over time after TCPC completion. Copyright © 2015 Elsevier Inc. All rights reserved.

Volcanic eruptions on Io: Heat flow, resurfacing, and lava composition

NASA Astrophysics Data System (ADS)

Blaney, Diana L.; Johnson, Torrence V.; Matson, Dennis L.; Veeder, Glenn J.

1995-01-01

We model an infrared outburst on Io as being due to a large, erupting lava flow which increased its area at a rate of 1.5 x 105/sq m and cooled from 1225 to 555 K over the 2.583-hr period of observation. The inferred effusion rate of 3 x 105 cu m/sec for this eruption is very high, but is not unprece- dented on the Earth and is similar to the high eruption rates suggested for early lunar volcanism. Eruptions occur approxi- mately 6% of the time on Io. These eruptions provide ample resurfacing to explain Io's lack of impact craters. We suggest that the large total radiometric heat flow, 1014 W, and the size and temperature distribution of the thermal anomalies (McEwen et al. 1992; Veeder et al. 1994) can be accounted for by a series of silicate lava flows in various stages of cooling. We propose that the whole suite of Io's currently observed thermal anomalies was produced by multiple, high-eruptive-rate silicate flows within the past century.

Volcanic eruptions on Io: Heat flow, resurfacing, and lava composition

NASA Technical Reports Server (NTRS)

Blaney, Diana L.; Johnson, Torrence V.; Matson, Dennis L.; Veeder, Glenn J.

1995-01-01

We model an infrared outburst on Io as being due to a large, erupting lava flow which increased its area at a rate of 1.5 x 10(exp 5)/sq m and cooled from 1225 to 555 K over the 2.583-hr period of observation. The inferred effusion rate of 3 x 10(exp 5) cu m/sec for this eruption is very high, but is not unprece- dented on the Earth and is similar to the high eruption rates suggested for early lunar volcanism. Eruptions occur approxi- mately 6% of the time on Io. These eruptions provide ample resurfacing to explain Io's lack of impact craters. We suggest that the large total radiometric heat flow, 10(exp 14) W, and the size and temperature distribution of the thermal anomalies (McEwen et al. 1992; Veeder et al. 1994) can be accounted for by a series of silicate lava flows in various stages of cooling. We propose that the whole suite of Io's currently observed thermal anomalies was produced by multiple, high-eruptive-rate silicate flows within the past century.

Studies of fluid flow indicators, Pacific margin of Costa Rica

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

Silver, E.; McAdoo, B.; Langseth, M.

Seismic reflection profiles off Costa Rica image a decrease in thickness of the underthrust sedimentary section from the Middle America Trench, implying a significant reduction of porosity in the outer 3-5 km from the trench and a source of vent water through the wedge. We encountered no evidence of discrete fluid venting over the outer 3-5 km of this margin from dives using the ALVIN submersible or from heat flow measurements (based on absence of chemosynthetic vent communities and heat flow anomalies in this zone). Vent communities occur farther upslope, associated with a series of out-of-sequence thrusts, with two mudmore » diapirs, and a mid-slope canyon. We infer that fracture permeability dominates in the out-of-sequence thrusts, upflow of fluid-rich muds in the diapir, and focusing of fluid flow in the canyon. Over 100 heat flow observations on the wedge and incoming COCOS plate showed a broad area of anomalously low heat flow (13 mW/m{sup 2}) seaward of the frontal thrust, whereas the expected heat flow for ocean crust of early Miocene age is seven times greater. The very low regional heat flow may reflect refrigeration by vigorous sea water flow through the upper crust pillow basalts. Heat flow increases to about 30 mW/m{sup 2} throughout the lower slope to mid-slope, implying a combination of widespread fluid venting, reheating of the cooled crust and frictional heating at the base of the wedge. The lack of discrete vents over the outer 3-5 km of the margin indicates diffuse flow and likely temporal episodicity, as this region has been aseismic since 1950.« less

Studies of fluid flow indicators, Pacific margin of Costa Rica

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

Silver, E.; McAdoo, B.; Langseth, M.

Seismic reflection profiles off Costa Rica image a decrease in thickness of the underthrust sedimentary section from the Middle America Trench, implying a significant reduction of porosity in the outer 3-5 km from the trench and a source of vent water through the wedge. We encountered no evidence of discrete fluid venting over the outer 3-5 km of this margin from dives using the ALVIN submersible or from heat flow measurements (based on absence of chemosynthetic vent communities and heat flow anomalies in this zone). Vent communities occur farther upslope, associated with a series of out-of-sequence thrusts, with two mudmore » diapirs, and a mid-slope canyon. We infer that fracture permeability dominates in the out-of-sequence thrusts, upflow of fluid-rich muds in the diapir, and focusing of fluid flow in the canyon. Over 100 heat flow observations on the wedge and incoming COCOS plate showed a broad area of anomalously low heat flow (13 mW/m[sup 2]) seaward of the frontal thrust, whereas the expected heat flow for ocean crust of early Miocene age is seven times greater. The very low regional heat flow may reflect refrigeration by vigorous sea water flow through the upper crust pillow basalts. Heat flow increases to about 30 mW/m[sup 2] throughout the lower slope to mid-slope, implying a combination of widespread fluid venting, reheating of the cooled crust and frictional heating at the base of the wedge. The lack of discrete vents over the outer 3-5 km of the margin indicates diffuse flow and likely temporal episodicity, as this region has been aseismic since 1950.« less

Western state instream flow programs: a comparative assessment

USGS Publications Warehouse

McKinney, Matthew J.; Taylor, Jonathan G.

1988-01-01

During their early history, Western States water rights laws were primarily means for facilitating and regulating water diversions for offstream, consumptive use. More recently, a countervailing concern for instream values such as fish and wildlife habitat, recreation, aesthetic values, and water quality has emerged in the legislative and administrative handling of water rights. As of 1988, the Western United States show a variety of approaches to balancing instream and diversion water rights, from zero control through administrative actions to legislatively established rights for guaranteed instream flows. The nine Western States that have adopted statutory instream flow protection programs include Alaska, Colorado, Hawaii, Idaho, Montana, Oregon, Utah, Washington, and Wyoming. Arizona, California, and Nevada have relied, to date, on administrative and judicial decisions, while New Mexico has established no mechanism for protecting instream water uses. In the States with statutory protection, instream water uses are granted the same legal status as any other water uses under the prior appropriation doctrine. The success of instream flow protection has been remarkable, given the controversial nature of the issue, with nearly 2,000 stream reaches protected.

Revisiting the Swaziland Supergroup: New Approaches to Examining Evidence for Early Life on Earth

NASA Technical Reports Server (NTRS)

Walsh, M. M.; Westall, F.

2000-01-01

The re-examination by SEM of 3.4 Ga fossiliferous carbonaceous cherts reveals fungal contaminants in addition to indigenous microfossils. Weathered volcanic flows associated with fossiliferous chert layers offer a promising area for further study of early life on Earth.

Multicentric Standardized Flow Cytometry Routine Assessment of Patients With Sepsis to Predict Clinical Worsening.

PubMed

Daix, Thomas; Guerin, Estelle; Tavernier, Elsa; Mercier, Emmanuelle; Gissot, Valérie; Hérault, Olivier; Mira, Jean-Paul; Dumas, Florence; Chapuis, Nicolas; Guitton, Christophe; Béné, Marie C; Quenot, Jean-Pierre; Tissier, Cindy; Guy, Julien; Piton, Gaël; Roggy, Anne; Muller, Grégoire; Legac, Éric; de Prost, Nicolas; Khellaf, Mehdi; Wagner-Ballon, Orianne; Coudroy, Rémi; Dindinaud, Elodie; Uhel, Fabrice; Roussel, Mikaël; Lafon, Thomas; Jeannet, Robin; Vargas, Frédéric; Fleureau, Catherine; Roux, Mickaël; Allou, Kaoutar; Vignon, Philippe; Feuillard, Jean; François, Bruno

2018-04-26

In this study, we primarily sought to assess the ability of flow cytometry to predict early clinical deterioration and overall survival in patients with sepsis admitted in the ED and ICU. Patients admitted for community-acquired acute sepsis from 11 hospital centers were eligible. Early (day 7) and late (day 28) deaths were notified. Levels of CD64 pos granulocytes, CD16 pos monocytes, CD16 dim immature granulocytes (IGs), and T and B lymphocytes were assessed by flow cytometry using an identical, cross-validated, robust, and simple consensus standardized protocol in each center. Among 1,062 patients screened, 781 patients with confirmed sepsis were studied (age, 67 ± 48 years; Simplified Acute Physiology Score II, 36 ± 17; Sequential Organ Failure Assessment, 5 ± 4). Patients were divided into three groups (sepsis, severe sepsis, and septic shock) on day 0 and on day 2. On day 0, patients with sepsis exhibited increased levels of CD64 pos granulocytes, CD16 pos monocytes, and IGs with T-cell lymphopenia. Clinical severity was associated with higher percentages of IGs and deeper T-cell lymphopenia. IG percentages tended to be higher in patients whose clinical status worsened on day 2 (35.1 ± 35.6 vs 43.5 ± 35.2, P = .07). Increased IG percentages were also related to occurrence of new organ failures on day 2. Increased IG percentages, especially when associated with T-cell lymphopenia, were independently associated with early (P < .01) and late (P < .01) death. Increased circulating IGs at the acute phase of sepsis are linked to clinical worsening, especially when associated with T-cell lymphopenia. Early flow cytometry could help clinicians to target patients at high risk of clinical deterioration. ClinicalTrials.gov; No.: NCT01995448; URL: www.clinicaltrials.gov. Copyright © 2018 American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.

Early in vivo experience with the pediatric continuous-flow total artificial heart.

PubMed

Karimov, Jamshid H; Horvath, David J; Byram, Nicole; Sunagawa, Gengo; Kuban, Barry D; Gao, Shengqiang; Dessoffy, Raymond; Fukamachi, Kiyotaka

2018-03-30

Heart transplantation in infants and children is an accepted therapy for end-stage heart failure, but donor organ availability is low and always uncertain. Mechanical circulatory support is another standard option, but there is a lack of intracorporeal devices due to size and functional range. The purpose of this study was to evaluate the in vivo performance of our initial prototype of a pediatric continuous-flow total artificial heart (P-CFTAH), comprising a dual pump with one motor and one rotating assembly, supported by a hydrodynamic bearing. In acute studies, the P-CFTAH was implanted in 4 lambs (average weight: 28.7 ± 2.3 kg) via a median sternotomy under cardiopulmonary bypass. Pulmonary and systemic pump performance parameters were recorded. The experiments showed good anatomical fit and easy implantation, with an average aortic cross-clamp time of 98 ± 18 minutes. Baseline hemodynamics were stable in all 4 animals (pump speed: 3.4 ± 0.2 krpm; pump flow: 2.1 ± 0.9 liters/min; power: 3.0 ± 0.8 W; arterial pressure: 68 ± 10 mm Hg; left and right atrial pressures: 6 ± 1 mm Hg, for both). Any differences between left and right atrial pressures were maintained within the intended limit of ±5 mm Hg over a wide range of ratios of systemic-to-pulmonary vascular resistance (0.7 to 12), with and without pump-speed modulation. Pump-speed modulation was successfully performed to create arterial pulsation. This initial P-CFTAH prototype met the proposed requirements for self-regulation, performance, and pulse modulation. Copyright © 2018 International Society for the Heart and Lung Transplantation. Published by Elsevier Inc. All rights reserved.

Mechanisms for renal blood flow control early in diabetes as revealed by chronic flow measurement and transfer function analysis.

PubMed

Bell, Tracy D; DiBona, Gerald F; Wang, Ying; Brands, Michael W

2006-08-01

The purpose of this study was to establish the roles of the myogenic response and the TGF mechanism in renal blood flow (RBF) control at the very earliest stages of diabetes. Mean arterial pressure (MAP) and RBF were measured continuously, 18 h/d, in uninephrectomized control and diabetic rats, and transfer function analysis was used to determine the dynamic autoregulatory efficiency of the renal vasculature. During the control period, MAP averaged 91 +/- 0.5 and 89 +/- 0.4 mmHg, and RBF averaged 8.0 +/- 0.1 and 7.8 +/- 0.1 ml/min in the control and diabetic groups, respectively. Induction of diabetes with streptozotocin caused a marked and progressive increase in RBF in the diabetic rats, averaging 10 +/- 6% above control on day 1 of diabetes and 22 +/- 3 and 34 +/- 1% above control by the end of diabetes weeks 1 and 2. MAP increased approximately 9 mmHg during the 2 wk in the diabetic rats, and renal vascular resistance decreased. Transfer function analysis revealed significant increases in gain to positive values over the frequency ranges of both the TGF and myogenic mechanisms, beginning on day 1 of diabetes and continuing through day 14. These very rapid increases in RBF and transfer function gain suggest that autoregulation is impaired at the very onset of hyperglycemia in streptozotocin-induced type 1 diabetes and may play an important role in the increase in RBF and GFR in diabetes. Together with previous reports of decreases in chronically measured cardiac output and hindquarter blood flow, this suggests that there may be differential effects of diabetes on RBF versus nonrenal BF control.

Rest and exercise echocardiography for early detection of pulmonary hypertension.

PubMed

Kusunose, Kenya; Yamada, Hirotsugu

2016-03-01

Early detection of pulmonary hypertension (PH) is essential to ensure that patients receive timely and appropriate treatment for this progressive disease. Rest and exercise echocardiography has been used to screen patients in an attempt to identify early stage PH. However, current PH guidelines recommend against exercise tests because of the lack of evidence. We reviewed previous studies to discuss the current standpoint concerning rest and exercise echocardiography in PH. Around 20 exercise echocardiography studies were included to assess the cutoff value for exercise-induced pulmonary hypertension (EIPH). Approximately 40 exercise echocardiography studies were also included to evaluate the pulmonary artery pressure-flow relationship as assessed by the slope of the mean pulmonary artery pressure and cardiac output (ΔmPAP/ΔQ). There were several EIPH and ΔmPAP/ΔQ reference values in individuals with pulmonary vascular disease. We believed that assessing the ΔmPAP/ΔQ makes sense from a physiological standpoint, and the clinical value should be confirmed in future studies. Exercise echocardiography is an appealing alternative in PH. Further studies are needed to assess the prognostic value of the pulmonary artery pressure-flow relationship in high-risk subjects.

Impaired Endothelial Repair Capacity of Early Endothelial Progenitor Cells in Hypertensive Patients With Primary Hyperaldosteronemia: Role of 5,6,7,8-Tetrahydrobiopterin Oxidation and Endothelial Nitric Oxide Synthase Uncoupling.

PubMed

Chen, Long; Ding, Mei-Lin; Wu, Fang; He, Wen; Li, Jin; Zhang, Xiao-Yu; Xie, Wen-Li; Duan, Sheng-Zhong; Xia, Wen-Hao; Tao, Jun

2016-02-01

Although hyperaldosteronemia exerts detrimental impacts on vascular endothelium in addition to elevating blood pressure, the effects and molecular mechanisms of hyperaldosteronemia on early endothelial progenitor cell (EPC)-mediated endothelial repair after arterial damage are yet to be determined. The aim of this study was to investigate the endothelial repair capacity of early EPCs from hypertensive patients with primary hyperaldosteronemia (PHA). In vivo endothelial repair capacity of early EPCs from PHAs (n=20), age- and blood pressure-matched essential hypertension patients (n=20), and age-matched healthy subjects (n=20) was evaluated by transplantation into a nude mouse carotid endothelial denudation model. Endothelial function was evaluated by flow-mediated dilation of brachial artery in human subjects. In vivo endothelial repair capacity of early EPCs and flow-mediated dilation were impaired both in PHAs and in essential hypertension patients when compared with age-matched healthy subjects; however, the early EPC in vivo endothelial repair capacity and flow-mediated dilation of PHAs were impaired more severely than essential hypertension patients. Oral spironolactone improved early EPC in vivo endothelial repair capacity and flow-mediated dilation of PHAs. Increased oxidative stress, oxidative 5,6,7,8-tetrahydrobiopterin degradation, endothelial nitric oxide synthase uncoupling and decreased nitric oxide production were found in early EPCs from PHAs. Nicotinamide adenine dinucleotide phosphate oxidase subunit p47(phox) knockdown or 5,6,7,8-tetrahydrobiopterin supplementation attenuated endothelial nitric oxide synthase uncoupling and enhanced in vivo endothelial repair capacity of early EPCs from PHAs. In conclusion, PHAs exhibited more impaired endothelial repair capacity of early EPCs than did essential hypertension patients independent of blood pressure, which was associated with mineralocorticoid receptor-dependent oxidative stress and subsequently 5

Simulation of the early startup period of high-temperature heat pipes from the frozen state by a rarefied vapor self-diffusion model

NASA Technical Reports Server (NTRS)

Cao, Y.; Faghri, A.

1993-01-01

The heat pipe startup process is described physically and is divided into five periods for convenience of analysis. The literature survey revealed that none of the previous attempts to simulate the heat pipe startup process numerically were successful, since the rarefied vapor flow in the heat pipe was not considered. Therefore, a rarefied vapor self-diffusion model is proposed, and the early startup periods, in which the rarefied vapor flow is dominant within the heat pipe, are first simulated numerically. The numerical results show that large vapor density gradients existed along the heat pipe length, and the vapor flow reaches supersonic velocities when the density is extremely low. The numerical results are compared with the experimental data of the early startup period with good agreement.

Mid-tertiary ash flow tuff cauldrons, southwestern New Mexico

NASA Technical Reports Server (NTRS)

Elston, W. E.

1984-01-01

Characteristics of 28 known or suspected mid-Tertiary ash-flow tuff cauldrons in New Mexico are described. The largest region is 40 km in diameter, and erosional and block faulting processes have exposed levels as far down as the plutonic roots. The study supports a five-stage process: precursor, caldera collapse, early post-collapse, volcanism, major ring-fracture volcanism, and hydrothermal activity. The stages can repeat or the process can stop at any stage. Post-collapse lavas fell into two categories: cauldron lavas, derived from shallow defluidized residues of caldera-forming ash flow tuff eruption, and framework lavas, evolved from a siliceous pluton below the cauldron complex. The youngest caldera was shallow and formed from asymmetric subsidence and collapse of the caldera walls.

Terrestrial heat flow in east and southern Africa

NASA Astrophysics Data System (ADS)

Nyblade, Andrew A.; Pollack, Henry N.; Jones, D. L.; Podmore, Francis; Mushayandebvu, Martin

1990-10-01

We report 26 new heat flow and 13 radiogenic heat production measurements from Zimbabwe, Zambia and Tanzania, together with details and some revisions of 18 previous heat flow measurements by other investigators from Kenya and Tanzania. These measurements come from Archean cratons, Proterozoic mobile belts, and Mesozoic and Cenozoic rifts. Heat flow data from eight new sites in the Archean Zimbabwe Craton are consistent with previous measurements in the Archean Kaapvaal-Zimbabwe Craton and Limpopo Belt (Kalahari Craton) and do not change the mean heat flow of 47±2 mW m-2 (standard error of the mean) in the Kalahari Craton based on 53 previous measurements. Eight new sites in the Archean Tanzania Craton give a mean heat flow of 34±4 mW m-2. The mean heat flow from nine sites in the Proterozoic Mozambique Belt to the east of the Tanzania Craton in Kenya and Tanzania is 47±4 mW m-2. Twelve measurements in the Mesozoic rifted continental margin in east Africa give a mean heat flow of 68±4 mW m-2; four measurements in the Mesozoic Luangwa and Zambezi Rifts range from 44 to 110 mW m-2 with a mean of 76±14 mW m-2. In comparing heat flow in east and southern Africa, we observe a common heat flow pattern of increasing heat flow away from the centers of the Archean cratons. This pattern suggests a fundamental difference in lithospheric thermal structure between the Archean cratons and the Proterozoic and early Paleozoic mobile belts which surround them. Superimposed on this common pattern are two regional variations in heat flow. Heat flow in the Tanzania Craton is lower by about 13 mW m-2 than in the Kalahari Craton, and in the Mozambique Belt in east Africa heat flow is somewhat lower than in the southern African mobile belts at similar distances from the Archean cratonic margin. The two regional variations can be explained in several ways, none of which can as yet be elevated to a preferred status: (1) by variations in crustal heat production, (2) by thin

Accomplishing the genotype-specific serodiagnosis of single and dual Trypanosoma cruzi infections by flow cytometry Chagas-Flow ATE-IgG2a.

PubMed

Alessio, Glaucia Diniz; de Araújo, Fernanda Fortes; Sales Júnior, Policarpo Ademar; Gomes, Matheus de Souza; Amaral, Laurence Rodrigues do; Pascoal Xavier, Marcelo Antônio; Teixeira-Carvalho, Andréa; de Lana, Marta; Martins-Filho, Olindo Assis

2018-02-01

The methods currently available for genotype-specific diagnosis of T. cruzi infection still present relevant limitations, especially to identify mixed infection. In the present investigation, we have evaluated the performance of Chagas-Flow ATE-IgG2a test for early and late differential diagnosis of single and dual genotype-specific T. cruzi infections. Serum samples from Swiss mice at early and late stages of T. cruzi infection were assayed in parallel batches for genotype-specific diagnosis of single (TcI, TcVI or TcII) and dual (TcI+TcVI, TcVI+TcII or TcII+TcI) infections. The intrinsic reactivity to TcI, TcVI and TcII target antigens, including amastigote (AI/AVI/AII), trypomastigote-(TI/TVI/TII) and epimastigote (EI/EVI/EII), at specific reverse of serum dilutions (500 to 64,000), was employed to provide reliable decision-trees for "early" vs "late", "single vs "dual" and "genotype-specific" serology. The results demonstrated that selective set of attributes "EII 500/EI 2,000/AII 500" were able to provide high-quality accuracy (81%) to segregate early and late stages of T. cruzi infection. The sets "TI 2,000/AI 1,000/EII 1,000" and "TI 8,000/AII 32,000" presented expressive scores to discriminate single from dual T. cruzi infections at early (85%) and late stages (84%), respectively. Moreover, the attributes "TI 4,000/TVI 500/TII 1,000", "TI 16,000/EI 2,000/EII 2,000/AI 500/TVI 500" showed good performance for genotype-specific diagnosis at early stage of single (72%) and dual (80%) T. cruzi infections, respectively. In addition, the attributes "TI 4,000/AII 1,000/EVI 1,000", "TI 64,000/AVI 500/AI 2,000/AII 1,000/EII 4,000" showed moderate performance for genotype-specific diagnosis at late stage of single (69%) and dual (76%) T. cruzi infections, respectively. The sets of decision-trees were assembled to construct a sequential algorithm with expressive accuracy (81%) for serological diagnosis of T. cruzi infection. These findings engender new perspectives for

Landslide monitoring and early warning systems in Lower Austria - current situation and new developments

NASA Astrophysics Data System (ADS)

Thiebes, Benni; Glade, Thomas; Schweigl, Joachim; Jäger, Stefan; Canli, Ekrem

2014-05-01

Landslides represent significant hazards in the mountainous areas of Austria. The Regional Geological Surveys are responsible to inform and protect the population, and to mitigate damage to infrastructure. Efforts of the Regional Geological Survey of Lower Austria include detailed site investigations, the planning and installation of protective structures (e.g. rock fall nets) as well as preventive measures such as regional scale landslide susceptibility assessments. For potentially endangered areas, where protection works are not feasible or would simply be too costly, monitoring systems have been installed. However, these systems are dominantly not automatic and require regular field visits to take measurements. Therefore, it is difficult to establish any relation between initiating and controlling factors, thus to fully understand the underlying process mechanism which is essential for any early warning system. Consequently, the implementation of new state-of-the-art monitoring and early warning systems has been started. In this presentation, the design of four landslide monitoring and early warning systems is introduced. The investigated landslide process types include a deep-seated landslide, a rock fall site, a complex earth flow, and a debris flow catchment. The monitoring equipment was chosen depending on the landslide processes and their activity. It aims to allow for a detailed investigation of process mechanisms in relation to its triggers and for reliable prediction of future landslide activities. The deep-seated landslide will be investigated by manual and automatic inclinometers to get detailed insights into subsurface displacements. In addition, TDR sensors and a weather station will be employed to get a better understanding on the influence of rainfall on sub-surface hydrology. For the rockfall site, a wireless sensor network will be installed to get real-time information on acceleration and inclination of potentially unstable blocks. The movement

Early Warning System of Flood Disaster Based on Ultrasonic Sensors and Wireless Technology

NASA Astrophysics Data System (ADS)

Indrasari, W.; Iswanto, B. H.; Andayani, M.

2018-04-01

A flood disaster provides considerable losses to the people who live around the river. To mitigate losses of material due to flood disaster required an early warning system of flood disaster. For that reason, it necessary to design a system that provide alert to the people prior the flood disaster. And this paper describes development of a device for early detection system of flood disasters. This device consists of two ultrasonic sensors as a water level detector, and a water flow sensor as a water flow velocity sensor. The wireless technology and GSM is used as an information medium. The system is designed based on water level conditions in the Katulampa Dam, Bogor. Characterization of water level detector showed that the device effectively works in a range of water level of 14-250 cm, with a maximum relative error of 4.3%. Meanwhile the wireless works properly as far as 75 m, and the SMS transmission time is 8.20 second.

Applicable research in practice: understanding the hydrophilic and flow property measurements of impression materials.

PubMed

Perry, Ronald D; Goldberg, Jeffrey A; Benchimol, Jacques; Orfanidis, John

2006-10-01

The flow properties and hydrophilicity of an impression material are key factors that affect its performance. This article details in vitro studies comparing these properties in 1 polyether and several vinyl polysiloxane light-body impression materials. The first series of studies examined the materials' flow properties used in a "shark fin" measurement procedure to determine which exhibited superior flow characteristics. The second series of studies reviewed the hydrophilic properties of the materials. Video analysis was used to record contact angle measurements at the early- and late-stage working times. Results showed 1 polyether material to be more hydrophilic. Applying this knowledge to practice, the authors present a clinical case in which a polyether's superior flow and quality of detail were used to make impressions for a patient receiving 8 single-unit zirconia crowns.

Oxygen profile and clogging in vertical flow sand filters for on-site wastewater treatment.

PubMed

Petitjean, A; Forquet, N; Boutin, C

2016-04-01

13 million people (about 20% of the population) use on-site wastewater treatment in France. Buried vertical sand filters are often built, especially when the soil permeability is not sufficient for septic tank effluent infiltration in undisturbed soil. Clogging is one of the main problems deteriorating the operation of vertical flow filters for wastewater treatment. The extent of clogging is not easily assessed, especially in buried vertical flow sand filters. We suggest examining two possible ways of detecting early clogging: (1) NH4-N/NO3-N outlet concentration ratio, and (2) oxygen measurement within the porous media. Two pilot-scale filters were equipped with probes for oxygen concentration measurements and samples were taken at different depths for pollutant characterization. Influent and effluent grab-samples were taken three times a week. The systems were operated using batch-feeding of septic tank effluent. Qualitative description of oxygen transfer processes under unclogged and clogged conditions is presented. NH4-N outlet concentration appears to be useless for early clogging detection. However, NO3-N outlet concentration and oxygen content allows us to diagnose the early clogging of the system. Copyright © 2016 Elsevier Ltd. All rights reserved.

Direct numerical simulation of supercritical gas flow in complex nanoporous media: Elucidating the relationship between permeability and pore space geometry

NASA Astrophysics Data System (ADS)

Landry, C. J.; Prodanovic, M.; Eichhubl, P.

2015-12-01

Mudrocks and shales are currently a significant source of natural gas and understanding the basic transport properties of these formations is critical to predicting long-term production, however, the nanoporous nature of mudrocks presents a unique challenge. Mudrock pores are predominantly in the range of 1-100 nm, and within this size range the flow of gas at reservoir conditions will fall within the slip-flow and early transition-flow regime (0.001 < Kn < 1.0). Therefore, flow-rates will significantly deviate from Navier-Stokes predictions. Currently, the study of slip-flows is mostly limited to simple tube and channel geometries, but the geometry of mudrock pores is often sponge-like (organic matter) and/or platy (clays). Here we present a local effective viscosity lattice Boltzmann model (LEV-LBM) constructed for flow simulation in the slip- and early-transition flow regimes, adapted here for complex geometries. At the macroscopic scale the LEV-LBM is parameterized with local effective viscosities at each node to capture the variance of the mean free path of gas molecules in a bounded system. The LEV-LBM is first validated in simple tube geometries, where excellent agreement with linearized Boltzmann solutions is found for Knudsen numbers up to 1.0. The LEV-LBM is then employed to quantify the length effect on the apparent permeability of tubes, which suggests pore network modeling of flow in the slip and early-transition regime will result in overestimation unless the length effect is considered. Furthermore, the LEV-LBM is used to evaluate the predictive value of commonly measured pore geometry characteristics such as porosity, pore size distribution, and specific solid surface area for the calculation of permeability. We show that bundle of tubes models grossly overestimate apparent permeability, as well as underestimate the increase in apparent permeability with decreasing pressure as a result of excluding topology and pore shape from calculations.

Low-flow, base-flow, and mean-flow regression equations for Pennsylvania streams

USGS Publications Warehouse

Stuckey, Marla H.

2006-01-01

Low-flow, base-flow, and mean-flow characteristics are an important part of assessing water resources in a watershed. These streamflow characteristics can be used by watershed planners and regulators to determine water availability, water-use allocations, assimilative capacities of streams, and aquatic-habitat needs. Streamflow characteristics are commonly predicted by use of regression equations when a nearby streamflow-gaging station is not available. Regression equations for predicting low-flow, base-flow, and mean-flow characteristics for Pennsylvania streams were developed from data collected at 293 continuous- and partial-record streamflow-gaging stations with flow unaffected by upstream regulation, diversion, or mining. Continuous-record stations used in the regression analysis had 9 years or more of data, and partial-record stations used had seven or more measurements collected during base-flow conditions. The state was divided into five low-flow regions and regional regression equations were developed for the 7-day, 10-year; 7-day, 2-year; 30-day, 10-year; 30-day, 2-year; and 90-day, 10-year low flows using generalized least-squares regression. Statewide regression equations were developed for the 10-year, 25-year, and 50-year base flows using generalized least-squares regression. Statewide regression equations were developed for harmonic mean and mean annual flow using weighted least-squares regression. Basin characteristics found to be significant explanatory variables at the 95-percent confidence level for one or more regression equations were drainage area, basin slope, thickness of soil, stream density, mean annual precipitation, mean elevation, and the percentage of glaciation, carbonate bedrock, forested area, and urban area within a basin. Standard errors of prediction ranged from 33 to 66 percent for the n-day, T-year low flows; 21 to 23 percent for the base flows; and 12 to 38 percent for the mean annual flow and harmonic mean, respectively. The

Computational and Experimental Study of Supersonic Nozzle Flow and Shock Interactions

NASA Technical Reports Server (NTRS)

Carter, Melissa B.; Elmiligui, Alaa A.; Nayani, Sudheer N.; Castner, Ray; Bruce, Walter E., IV; Inskeep, Jacob

2015-01-01

This study focused on the capability of NASA Tetrahedral Unstructured Software System's CFD code USM3D capability to predict the interaction between a shock and supersonic plume flow. Previous studies, published in 2004, 2009 and 2013, investigated USM3D's supersonic plume flow results versus historical experimental data. This current study builds on that research by utilizing the best practices from the early papers for properly capturing the plume flow and then adding a wedge acting as a shock generator. This computational study is in conjunction with experimental tests conducted at the Glenn Research Center 1'x1' Supersonic Wind Tunnel. The comparison of the computational and experimental data shows good agreement for location and strength of the shocks although there are vertical shifts between the data sets that may be do to the measurement technique.

Measuring flow velocity and flow direction by spatial and temporal analysis of flow fluctuations.

PubMed

Chagnaud, Boris P; Brücker, Christoph; Hofmann, Michael H; Bleckmann, Horst

2008-04-23

If exposed to bulk water flow, fish lateral line afferents respond only to flow fluctuations (AC) and not to the steady (DC) component of the flow. Consequently, a single lateral line afferent can encode neither bulk flow direction nor velocity. It is possible, however, for a fish to obtain bulk flow information using multiple afferents that respond only to flow fluctuations. We show by means of particle image velocimetry that, if a flow contains fluctuations, these fluctuations propagate with the flow. A cross-correlation of water motion measured at an upstream point with that at a downstream point can then provide information about flow velocity and flow direction. In this study, we recorded from pairs of primary lateral line afferents while a fish was exposed to either bulk water flow, or to the water motion caused by a moving object. We confirm that lateral line afferents responded to the flow fluctuations and not to the DC component of the flow, and that responses of many fiber pairs were highly correlated, if they were time-shifted to correct for gross flow velocity and gross flow direction. To prove that a cross-correlation mechanism can be used to retrieve the information about gross flow velocity and direction, we measured the flow-induced bending motions of two flexible micropillars separated in a downstream direction. A cross-correlation of the bending motions of these micropillars did indeed produce an accurate estimate of the velocity vector along the direction of the micropillars.

Flow chemistry vs. flow analysis.

PubMed

Trojanowicz, Marek

2016-01-01

The flow mode of conducting chemical syntheses facilitates chemical processes through the use of on-line analytical monitoring of occurring reactions, the application of solid-supported reagents to minimize downstream processing and computerized control systems to perform multi-step sequences. They are exactly the same attributes as those of flow analysis, which has solid place in modern analytical chemistry in several last decades. The following review paper, based on 131 references to original papers as well as pre-selected reviews, presents basic aspects, selected instrumental achievements and developmental directions of a rapidly growing field of continuous flow chemical synthesis. Interestingly, many of them might be potentially employed in the development of new methods in flow analysis too. In this paper, examples of application of flow analytical measurements for on-line monitoring of flow syntheses have been indicated and perspectives for a wider application of real-time analytical measurements have been discussed. Copyright © 2015 Elsevier B.V. All rights reserved.

Heat transfer and fluid mechanics measurements in transitional boundary layer flows

NASA Technical Reports Server (NTRS)

Wang, T.; Simon, T. W.; Buddhavarapu, J.

1985-01-01

Experimental results are presented to document hydrodynamic and thermal development of flat-plate boundary layers undergoing natural transition. Local heat transfer coefficients, skin friction coefficients and profiles of velocity, temperature and Reynolds normal and shear stresses are presented. A case with no transition and transitional cases with 0.68% and 2.0% free-stream disturbance intensities were investigated. The locations of transition are consistent with earlier data. A late-laminar state with significant levels of turbulence is documented. In late-transitional and early-turbulent flows, turbulent Prandtl number and conduction layer thickness values exceed, and the Reynolds analogy factor is less than, values previously measured in fully turbulent flows.

Label-free counting of circulating cells by in vivo photoacoustic flow cytometry

NASA Astrophysics Data System (ADS)

Zhou, Quanyu; Yang, Ping; Wang, Qiyan; Pang, Kai; Zhou, Hui; He, Hao; Wei, Xunbin

2018-02-01

Melanoma, developing from melanocytes, is the most serious type of skin cancer. Circulating melanoma cells, the prognosis marker for metastasis, are present in the circulation at the early stage. Thus, quantitative detection of rare circulating melanoma cells is essential for monitoring tumor metastasis and prognosis evaluation. Compared with in vitro assays, in vivo flow cytometry is able to identify circulating tumor cells without drawing blood. Here, we built in vivo photoacoustic flow cytometry based on the high absorption coefficient of melanoma cells, which is applied to labelfree counting of circulating melanoma cells in tumor-bearing mice.

Spiral Flow Phantom for Ultrasound Flow Imaging Experimentation.

PubMed

Yiu, Billy Y S; Yu, Alfred C H

2017-12-01

As new ultrasound flow imaging methods are being developed, there is a growing need to devise appropriate flow phantoms that can holistically assess the accuracy of the derived flow estimates. In this paper, we present a novel spiral flow phantom design whose Archimedean spiral lumen naturally gives rise to multi-directional flow over all possible angles (i.e., from 0° to 360°). Developed using lost-core casting principles, the phantom geometry comprised a three-loop spiral (4-mm diameter and 5-mm pitch), and it was set to operate in steady flow mode (3 mL/s flow rate). After characterizing the flow pattern within the spiral vessel using computational fluid dynamics (CFD) simulations, the phantom was applied to evaluate the performance of color flow imaging (CFI) and high-frame-rate vector flow imaging. Significant spurious coloring artifacts were found when using CFI to visualize flow in the spiral phantom. In contrast, using vector flow imaging (least-squares multi-angle Doppler based on a three-transmit and three-receive configuration), we observed consistent depiction of flow velocity magnitude and direction within the spiral vessel lumen. The spiral flow phantom was also found to be a useful tool in facilitating demonstration of dynamic flow visualization based on vector projectile imaging. Overall, these results demonstrate the spiral flow phantom's practical value in analyzing the efficacy of ultrasound flow estimation methods.

Modeling Flow Past a Tilted Vena Cava Filter

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

Singer, M A; Wang, S L

Inferior vena cava filters are medical devices used to prevent pulmonary embolism (PE) from deep vein thrombosis. In particular, retrievable filters are well-suited for patients who are unresponsive to anticoagulation therapy and whose risk of PE decreased with time. The goal of this work is to use computational fluid dynamics to evaluate the flow past an unoccluded and partially occluded Celect inferior vena cava filter. In particular, the hemodynamic response to thrombus volume and filter tilt is examined, and the results are compared with flow conditions that are known to be thrombogenic. A computer model of the filter inside amore » model vena cava is constructed using high resolution digital photographs and methods of computer aided design. The models are parameterized using the Overture software framework, and a collection of overlapping grids is constructed to discretize the flow domain. The incompressible Navier-Stokes equations are solved, and the characteristics of the flow (i.e., velocity contours and wall shear stresses) are computed. The volume of stagnant and recirculating flow increases with thrombus volume. In addition, as the filter increases tilt, the cava wall adjacent to the tilted filter is subjected to low velocity flow that gives rise to regions of low wall shear stress. The results demonstrate the ease of IVC filter modeling with the Overture software framework. Flow conditions caused by the tilted Celect filter may elevate the risk of intrafilter thrombosis and facilitate vascular remodeling. This latter condition also increases the risk of penetration and potential incorporation of the hook of the filter into the vena caval wall, thereby complicating filter retrieval. Consequently, severe tilt at the time of filter deployment may warrant early clinical intervention.« less

Ice Flow in the North East Greenland Ice Stream

NASA Technical Reports Server (NTRS)

Joughin, Ian; Kwok, Ron; Fahnestock, M.; MacAyeal, Doug

1999-01-01

Early observations with ERS-1 SAR image data revealed a large ice stream in North East Greenland (Fahnestock 1993). The ice stream has a number of the characteristics of the more closely studied ice streams in Antarctica, including its large size and gross geometry. The onset of rapid flow close to the ice divide and the evolution of its flow pattern, however, make this ice stream unique. These features can be seen in the balance velocities for the ice stream (Joughin 1997) and its outlets. The ice stream is identifiable for more than 700 km, making it much longer than any other flow feature in Greenland. Our research goals are to gain a greater understanding of the ice flow in the northeast Greenland ice stream and its outlet glaciers in order to assess their impact on the past, present, and future mass balance of the ice sheet. We will accomplish these goals using a combination of remotely sensed data and ice sheet models. We are using satellite radar interferometry data to produce a complete maps of velocity and topography over the entire ice stream. We are in the process of developing methods to use these data in conjunction with existing ice sheet models similar to those that have been used to improve understanding of the mechanics of flow in Antarctic ice streams.

Constraints of nonresponding flows based on cross layers in the networks

NASA Astrophysics Data System (ADS)

Zhou, Zhi-Chao; Xiao, Yang; Wang, Dong

2016-02-01

In the active queue management (AQM) scheme, core routers cannot manage and constrain user datagram protocol (UDP) data flows by the sliding window control mechanism in the transport layer due to the nonresponsive nature of such traffic flows. However, the UDP traffics occupy a large part of the network service nowadays which brings a great challenge to the stability of the more and more complex networks. To solve the uncontrollable problem, this paper proposes a cross layers random early detection (CLRED) scheme, which can control the nonresponding UDP-like flows rate effectively when congestion occurs in the access point (AP). The CLRED makes use of the MAC frame acknowledgement (ACK) transmitting congestion information to the sources nodes and utilizes the back-off windows of the MAC layer throttling data rate. Consequently, the UDP-like flows data rate can be restrained timely by the sources nodes in order to alleviate congestion in the complex networks. The proposed CLRED can constrain the nonresponsive flows availably and make the communication expedite, so that the network can sustain stable. The simulation results of network simulator-2 (NS2) verify the proposed CLRED scheme.

Design space exploration for early identification of yield limiting patterns

NASA Astrophysics Data System (ADS)

Li, Helen; Zou, Elain; Lee, Robben; Hong, Sid; Liu, Square; Wang, JinYan; Du, Chunshan; Zhang, Recco; Madkour, Kareem; Ali, Hussein; Hsu, Danny; Kabeel, Aliaa; ElManhawy, Wael; Kwan, Joe

2016-03-01

In order to resolve the causality dilemma of which comes first, accurate design rules or real designs, this paper presents a flow for exploration of the layout design space to early identify problematic patterns that will negatively affect the yield. A new random layout generating method called Layout Schema Generator (LSG) is reported in this paper, this method generates realistic design-like layouts without any design rule violation. Lithography simulation is then used on the generated layout to discover the potentially problematic patterns (hotspots). These hotspot patterns are further explored by randomly inducing feature and context variations to these identified hotspots through a flow called Hotspot variation Flow (HSV). Simulation is then performed on these expanded set of layout clips to further identify more problematic patterns. These patterns are then classified into design forbidden patterns that should be included in the design rule checker and legal patterns that need better handling in the RET recipes and processes.

The wall traction induced by flowing red blood cells in model microvessels and its potential mechanotransduction

NASA Astrophysics Data System (ADS)

Freund, Jonathan; Vermot, Julien

2013-11-01

There is evidence in early embryonic development, even well before advective oxygen transport is important, that the presence of red bloods cells per se trigger essential steps of normal vascular development. For example, showed that sequestration of blood cells early in the development of a mouse, such that the hematocrit is reduced, suppresses normal vascular network development. Vascular development also provides a model for remodeling and angiogenesis. We consider the transient stresses associated with blood cells flowing in model microvessels of comparable diameter to those at early stages of development (6 μm to 12 μm). A detailed simulation tool is used to show that passing blood cells present a significant fluctuating traction signature on the vessel wall, well above the mean stresses. This is particularly pronounced for slow flows (<= 50 μm/s) or small diameters (<= 7 μm), for which root-mean-square wall traction fluctuations can exceed their mean. These events potentially present mechanotranduction triggers that direct development or remodeling. Attenuation of such fluctuating tractions by a viscoelastic endothelial glycocalyx layer is also considered. NSF supported.

Diagnosis of Plasma Cell Dyscrasias and Monitoring of Minimal Residual Disease by Multiparametric Flow Cytometry

PubMed Central

Soh, Kah Teong; Tario, Joseph D.; Wallace, Paul K.

2018-01-01

Synopsis Plasma cell dyscrasia (PCD) is a heterogeneous disease which has seen a tremendous change in outcomes due to improved therapies. Over the last few decades, multiparametric flow cytometry has played an important role in the detection and monitoring of PCDs. Flow cytometry is a high sensitivity assay for early detection of minimal residual disease (MRD) that correlates well with progression-free survival and overall survival. Before flow cytometry can be effectively implemented in the clinical setting sample preparation, panel configuration, analysis, and gating strategies must be optimized to ensure accurate results. Current consensus methods and reporting guidelines for MRD testing are discussed. PMID:29128071

Early Use of Internet-Based Educational Resources: Effects on Students' Engagement Modes and Flow Experience

ERIC Educational Resources Information Center

Hedman, Leif; Sharafi, Parvaneh

2004-01-01

This case study explores how educational training and clinical practice that uses personal computers (PCs) and Personal Digital Assistants (PDAs) to access Internet-based medical information, affects the engagement modes of students, flow experience components, and IT-competence. A questionnaire assessing these variables was administered before…

Visualization of flow by vector analysis of multidirectional cine MR velocity mapping.

PubMed

Mohiaddin, R H; Yang, G Z; Kilner, P J

1994-01-01

We describe a noninvasive method for visualization of flow and demonstrate its application in a flow phantom and in the great vessels of healthy volunteers and patients with aortic and pulmonary arterial disease. The technique uses multidirectional MR velocity mapping acquired in selected planes. Maps of orthogonal velocity components were then processed into a graphic form immediately recognizable as flow. Cine MR velocity maps of orthogonal velocity components in selected planes were acquired in a flow phantom, 10 healthy volunteers, and 13 patients with dilated great vessels. Velocities were presented by multiple computer-generated streaks whose orientation, length, and movement corresponded to velocity vectors in the chosen plane. The velocity vector maps allowed visualization of complex patterns of primary and secondary flow in the thoracic aorta and pulmonary arteries. The technique revealed coherent, helical forward blood movements in the normal thoracic aorta during midsystole and a reverse flow during early diastole. Abnormal flow patterns with secondary vortices were seen in patients with dilated arteries. The potential of MR velocity vector mapping for in vitro and in vivo visualization of flow patterns is demonstrated. Although this study was limited to two-directional flow in a single anatomical plane, the method provides information that might advance our understanding of the human vascular system in health and disease. Further developments to reduce the acquisition time and the handling and presenting of three-directional velocity data are required to enhance the capability of this method.

A fast process development flow by applying design technology co-optimization

NASA Astrophysics Data System (ADS)

Chen, Yi-Chieh; Yeh, Shin-Shing; Ou, Tsong-Hua; Lin, Hung-Yu; Mai, Yung-Ching; Lin, Lawrence; Lai, Jun-Cheng; Lai, Ya Chieh; Xu, Wei; Hurat, Philippe

2017-03-01

Beyond 40 nm technology node, the pattern weak points and hotspot types increase dramatically. The typical patterns for lithography verification suffers huge turn-around-time (TAT) to handle the design complexity. Therefore, in order to speed up process development and increase pattern variety, accurate design guideline and realistic design combinations are required. This paper presented a flow for creating a cell-based layout, a lite realistic design, to early identify problematic patterns which will negatively affect the yield. A new random layout generating method, Design Technology Co-Optimization Pattern Generator (DTCO-PG), is reported in this paper to create cell-based design. DTCO-PG also includes how to characterize the randomness and fuzziness, so that it is able to build up the machine learning scheme which model could be trained by previous results, and then it generates patterns never seen in a lite design. This methodology not only increases pattern diversity but also finds out potential hotspot preliminarily. This paper also demonstrates an integrated flow from DTCO pattern generation to layout modification. Optical Proximity Correction, OPC and lithographic simulation is then applied to DTCO-PG design database to detect hotspots and then hotspots or weak points can be automatically fixed through the procedure or handled manually. This flow benefits the process evolution to have a faster development cycle time, more complexity pattern design, higher probability to find out potential hotspots in early stage, and a more holistic yield ramping operation.

History of Suction-Type Laminar-Flow Control with Emphasis on Flight Resrearch: Monographs in Aerospace History Number 13

NASA Technical Reports Server (NTRS)

Braslow, A. L.

1999-01-01

The paper contains the following sections: Foreword; Preface; Laminar-Flow Control Concepts and Scope of Monograph; Early Research on Suction-Type Laminar-Flow Control (Research from the 1930s through the War Years; Research from after World War II to the Mid-1960s); Post X-21 Research on Suction-Type Laminar-Flow Control; Status of Laminar-Flow Control Technology in the Mid-1990s; Glossary; Document 1-Aeronautics Panel, AACB, R&D Review, Report of the Subpanel on Aeronautic Energy Conservation/Fuels; Document 2-Report of Review Group on X-21A Laminar Flow Control Program; Document 3-Langley Research Center Announcement, Establishment of Laminar Flow Control Working Group; Document 4-Intercenter Agreement for Laminar Flow Control Leading Edge Glove Flights, LaRC and DFRC; Document 5-Flight Report NLF-144, of AFTIF-111 Aircraft with the TACT Wing Modified by a Natural Laminar Flow Glove; Document 6-Flight Record, F-16XL Supersonic Laminar Flow Control Aircraft; Index; and About the Author.

Fracture-induced flow and liquid metal transport during core formation

NASA Astrophysics Data System (ADS)

Jones, V.; Petford, N.; Rushmer, T.; Wertheim, D.

2008-12-01

The most important event in the early history of the earth was the separation of its iron-rich core. Core formation induced profound chemical fractionations and extracted into the core most of Earth's iron and siderophile elements (Ni, Co, Au, Pt, W, Re), leaving the silicate crust and mantle with strong depletions of these elements relative to primitive planetary material. Recent measurements of radiogenic 182W anomalies in the silicate Earth, Mars and differentiated meteorites imply that planetesimals segregated metallic cores within a few Myr of the origin of the solar system. Various models have been put forward to explain the physical nature of the segregation mechanism (Fe-diapirs, 'raining' through a magma ocean), and more recently melt flow via fractures. In this contribution we present the initial results of a numerical study into Fe segregation in a deforming silicate matrix that captures the temperature-dependent effect of liquid metal viscosity on the transport rate. Flow is driven by pressure gradients associated with impact deformation in a growing planetesimal and the fracture geometry is constrained by experimental data on naturally deformed H6 chondrite. Early results suggest that under dynamic conditions, fracture-driven melt flow can in principle be extremely rapid, leading to a significant draining of the Fe-liquid metal and siderophile trace element component on a timescale of hours to days. Fluid transport in planetesimals where deformation is the driving force provides an attractive and simple way of segregating Fe from host silicate as both precursor and primary agent of core formation

Representational dynamics of object recognition: Feedforward and feedback information flows.

PubMed

Goddard, Erin; Carlson, Thomas A; Dermody, Nadene; Woolgar, Alexandra

2016-03-01

Object perception involves a range of visual and cognitive processes, and is known to include both a feedfoward flow of information from early visual cortical areas to higher cortical areas, along with feedback from areas such as prefrontal cortex. Previous studies have found that low and high spatial frequency information regarding object identity may be processed over different timescales. Here we used the high temporal resolution of magnetoencephalography (MEG) combined with multivariate pattern analysis to measure information specifically related to object identity in peri-frontal and peri-occipital areas. Using stimuli closely matched in their low-level visual content, we found that activity in peri-occipital cortex could be used to decode object identity from ~80ms post stimulus onset, and activity in peri-frontal cortex could also be used to decode object identity from a later time (~265ms post stimulus onset). Low spatial frequency information related to object identity was present in the MEG signal at an earlier time than high spatial frequency information for peri-occipital cortex, but not for peri-frontal cortex. We additionally used Granger causality analysis to compare feedforward and feedback influences on representational content, and found evidence of both an early feedfoward flow and later feedback flow of information related to object identity. We discuss our findings in relation to existing theories of object processing and propose how the methods we use here could be used to address further questions of the neural substrates underlying object perception. Copyright © 2016 Elsevier Inc. All rights reserved.

Water flow and energy balance for a tropical dry semideciduous forest

NASA Astrophysics Data System (ADS)

Andrade, J. L.; Garruña-Hernandez, R.; Leon-Palomo, M.; Us-Santamaria, R.; Sima, J. L.

2013-05-01

Tropical forests cool down locally because increase water evaporation from the soil to the atmosphere, reduce albedo and help forming clouds that reflect solar radiation back to the atmosphere; this, aligned to the carbon catchment, increase forests value. We will present an estimation of the sap flow and energy balance for the tropical dry semideciduous forest at Kiuic, Yucatan, Mexico during a year. We use a meteorological tower equipped with a rain gauge, temperature and relative humidity, heat flow plates, thermocouples and volumetric soil water content. We recorded net radiation and soil heat flux and estimated sensible heat and latent heat. Besides, we estimated latent heat by measuring sap flow directly in tres using disispation constant heat probes during the rainy season. Results show the influence of the seasonality on net radiation, air temperatura and vapor pressure deficit, because during the dry season his variables were higher and with more duation than during the rainy and early dry season. Sap flow was different for trees belonging to the family Fabaceae compared to trees from other families.

Identification of early B cell precursors (stage 1 and 2 hematogones) in the peripheral blood.

PubMed

Kurzer, Jason H; Weinberg, Olga K

2018-05-25

Differentiating malignant B-lymphoblasts from early benign B cell precursors (hematogones) is a vital component of the diagnosis of B-lymphoblastic leukaemia. It has been previously reported that only late-stage B cell precursors circulate in the peripheral blood. Consequently, flow cytometric detection of cells with immunophenotypic findings similar to earlier stage precursors in the peripheral blood justifiably raises concern for involvement by B-lymphoblastic leukaemia. We report here, however, that benign early B cell precursors can indeed be detected in the peripheral blood, thus complicating the interpretation of flow cytometric findings derived from these sample types. A retrospective search of our collective databases identified 13 cases containing circulating early stage B cell precursors. The patients ranged in age from 15 days to 85 years old. All positive cases demonstrated that the earlier B cell precursors were associated with later stage precursors, a finding that could help differentiate these cells from B-lymphoblastic leukaemia. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Blunted postprandial reaction of portal venous flow in chronic liver disease, assessed with duplex Doppler: significance for prognosis.

PubMed

de Vries, P J; de Hooge, P; Hoekstra, J B; van Hattum, J

1994-12-01

To establish the effects of a meal on portal venous flow and the prognostic value of this parameter, 46 patients with chronic liver disease and 28 healthy subjects were examined with duplex Doppler before and after a meal. The measurements were completed in 40 patients and 21 healthy subjects. Postprandial portal venous diameter, blood velocity and quantitative flow were measured for 60 min. Mean baseline values were: 11.4 mm versus 10.2 mm (p = 0.019), 10.8 cm.s-1 versus 13.4 cm.s-1 (p = 0.015) and 668 ml.min-1 versus 646 ml.min-1 (p = 0.7) respectively. Spleen size was 15.0 cm versus 10.6 cm (p = 0.0001) respectively. Postprandial diameter, velocity and flow increased significantly in patients and controls (p = 0.0001 for all). Mean postprandial flow could best be described by a polynomial equation with a parabolic curve. Patients' curves were more blunted than controls', with significantly different regression constants (p = 0.025 and p = 0.029). All subjects were followed up for survival and variceal haemorrhage. The mean follow-up time was 47 months. Early maximum postprandial velocity (p = 0.041) and large spleen size (p = 0.002) were significantly related to an unfavourable prognosis for survival. Early maximum velocity was also related to increased variceal haemorrhage. This study shows that postprandial portal venous flow is blunted in patients with chronic liver disease. Postprandial portal venous flow may have prognostic significance.

Laser speckle imaging of rat retinal blood flow with hybrid temporal and spatial analysis method

NASA Astrophysics Data System (ADS)

Cheng, Haiying; Yan, Yumei; Duong, Timothy Q.

2009-02-01

Noninvasive monitoring of blood flow in retinal circulation will reveal the progression and treatment of ocular disorders, such as diabetic retinopathy, age-related macular degeneration and glaucoma. A non-invasive and direct BF measurement technique with high spatial-temporal resolution is needed for retinal imaging. Laser speckle imaging (LSI) is such a method. Currently, there are two analysis methods for LSI: spatial statistics LSI (SS-LSI) and temporal statistical LSI (TS-LSI). Comparing these two analysis methods, SS-LSI has higher signal to noise ratio (SNR) and TSLSI is less susceptible to artifacts from stationary speckle. We proposed a hybrid temporal and spatial analysis method (HTS-LSI) to measure the retinal blood flow. Gas challenge experiment was performed and images were analyzed by HTS-LSI. Results showed that HTS-LSI can not only remove the stationary speckle but also increase the SNR. Under 100% O2, retinal BF decreased by 20-30%. This was consistent with the results observed with laser Doppler technique. As retinal blood flow is a critical physiological parameter and its perturbation has been implicated in the early stages of many retinal diseases, HTS-LSI will be an efficient method in early detection of retina diseases.

Directed and Elliptic Flow of Charged Hadrons in 62.4 GeV Au+Au Collisions

NASA Astrophysics Data System (ADS)

Oldenburg, Markus

2004-10-01

The measurement of the azimuthal momentum distribution of particles produced in heavy-ion collisions reveals insight into the early stage of the system's evolution [1]. It is quantified by the Fourier coefficients vn of the distribution of particle momentum azimuth angle [2]. Theoretical models predict the first Fourier coefficient v1 ("directed flow") to be sensitive to a possible phase transition of normal nuclear matter to a quark-gluon plasma [3]. The second Fourier component v2 ("elliptic flow") is believed to be a signal of early thermalization of the created system of hot and dense nuclear matter [4]. We present results of directed and elliptic flow at √s_NN = 62.4 GeV, as measured by the STAR experiment at RHIC. Comparisons to model predictions and different analysis techniques will be made. [1] P.F. Kolb, J. Sollfrank, and U. Heinz, Phys. Rev. C 62, 054909 (2000). [2] S.A. Voloshin and Y. Zhang, Z. Phys. C 70, 665 (1996). [3] L.P. Csernai and D. Röhrich, Phys. Lett. B 458, 454 (1999). [4] D. Teaney, J. Lauret and E. Shuryak, Phys. Rev. Lett. 86, 4783 (2001).

Aortic, carotid intima-media thickness and flow- mediated dilation as markers of early atherosclerosis in a cohort of pediatric patients with rheumatic diseases.

PubMed

Del Giudice, Emanuela; Dilillo, Anna; Tromba, Luciana; La Torre, Giuseppe; Blasi, Sara; Conti, Fabrizio; Viola, Franca; Cucchiara, Salvatore; Duse, Marzia

2018-06-01

The aims of this study were to identify the presence of endothelial dysfunction as a marker of early atherosclerosis by measuring aortic and carotid intimal-medial thickness (aIMT and cIMT) and flow-mediated dilation (FMD) and their correlation with traditional and no traditional risk factors for atherosclerosis in children with rheumatic diseases. Thirty-nine patients (mean age 15.3 ± 5.7 years), 23 juvenile idiopathic arthritis, 9 juvenile spondyloarthropathies, 7 connective tissue diseases (mean disease duration and onset respectively 5 ± 3.6 and 10 ± 5 years), and 52 healthy children matched for sex and age were enrolled. Demographic data (age, sex, familiarity for cardiovascular disease), traditional risk factors for atherosclerosis (BMI, active and passive smoking, dyslipidemia), activity disease indexes (reactive count protein, erythrocyte sedimentation rate) autoantibodies, and complement tests were collected. aIMT, cIMT, and FMD were assessed following a standardized protocol by high-resolution ultrasonography. Patients resulted significantly more exposed to passive smoking and had a lower BMI and higher homocysteine level than controls. cIMT and aIMT were significantly higher in patients than controls (p < 0.001) and correlated with age at diagnosis (p < 0.001 r 0.516 and 0.706, respectively) but not with mean disease duration. FMD % was significantly reduced in patients compared to controls (p < 0.001). Subclinical atherosclerosis occurs in pediatric rheumatic diseases, mainly in early onset forms, and aIMT is an earlier marker of preclinical atherosclerosis. Premature endothelial dysfunction could be included in the follow-up of children with rheumatic disorders to plan prevention strategies of cardiovascular disease already in pediatrics.

Physical conditions on the early Earth.

PubMed

Lunine, Jonathan I

2006-10-29

The formation of the Earth as a planet was a large stochastic process in which the rapid assembly of asteroidal-to-Mars-sized bodies was followed by a more extended period of growth through collisions of these objects, facilitated by the gravitational perturbations associated with Jupiter. The Earth's inventory of water and organic molecules may have come from diverse sources, not more than 10% roughly from comets, the rest from asteroidal precursors to chondritic bodies and possibly objects near Earth's orbit for which no representative class of meteorites exists today in laboratory collections. The final assembly of the Earth included a catastrophic impact with a Mars-sized body, ejecting mantle and crustal material to form the Moon, and also devolatilizing part of the Earth. A magma ocean and steam atmosphere (possibly with silica vapour) existed briefly in this period, but terrestrial surface waters were below the critical point within 100 million years after Earth's formation, and liquid water existed continuously on the surface within a few hundred million years. Organic material delivered by comets and asteroids would have survived, in part, this violent early period, but frequent impacts of remaining debris probably prevented the continuous habitability of the Earth for one to several hundred million years. Planetary analogues to or records of this early time when life began include Io (heat flow), Titan (organic chemistry) and Venus (remnant early granites).

Mimicking the surface and prebiotic chemistry of early Earth using flow chemistry.

PubMed

Ritson, Dougal J; Battilocchio, Claudio; Ley, Steven V; Sutherland, John D

2018-05-08

When considering life's aetiology, the first questions that must be addressed are "how?" and "where?" were ostensibly complex molecules, considered necessary for life's beginning, constructed from simpler, more abundant feedstock molecules on primitive Earth. Previously, we have used multiple clues from the prebiotic synthetic requirements of (proto)biomolecules to pinpoint a set of closely related geochemical scenarios that are suggestive of flow and semi-batch chemistries. We now wish to report a multistep, uninterrupted synthesis of a key heterocycle (2-aminooxazole) en route to activated nucleotides starting from highly plausible, prebiotic feedstock molecules under conditions which mimic this scenario. Further consideration of the scenario has uncovered additional pertinent and novel aspects of prebiotic chemistry, which greatly enhance the efficiency and plausibility of the synthesis.

Prediction of spatially explicit rainfall intensity-duration thresholds for post-fire debris-flow generation in the western United States

NASA Astrophysics Data System (ADS)

Staley, Dennis; Negri, Jacquelyn; Kean, Jason

2016-04-01

Population expansion into fire-prone steeplands has resulted in an increase in post-fire debris-flow risk in the western United States. Logistic regression methods for determining debris-flow likelihood and the calculation of empirical rainfall intensity-duration thresholds for debris-flow initiation represent two common approaches for characterizing hazard and reducing risk. Logistic regression models are currently being used to rapidly assess debris-flow hazard in response to design storms of known intensities (e.g. a 10-year recurrence interval rainstorm). Empirical rainfall intensity-duration thresholds comprise a major component of the United States Geological Survey (USGS) and the National Weather Service (NWS) debris-flow early warning system at a regional scale in southern California. However, these two modeling approaches remain independent, with each approach having limitations that do not allow for synergistic local-scale (e.g. drainage-basin scale) characterization of debris-flow hazard during intense rainfall. The current logistic regression equations consider rainfall a unique independent variable, which prevents the direct calculation of the relation between rainfall intensity and debris-flow likelihood. Regional (e.g. mountain range or physiographic province scale) rainfall intensity-duration thresholds fail to provide insight into the basin-scale variability of post-fire debris-flow hazard and require an extensive database of historical debris-flow occurrence and rainfall characteristics. Here, we present a new approach that combines traditional logistic regression and intensity-duration threshold methodologies. This method allows for local characterization of both the likelihood that a debris-flow will occur at a given rainfall intensity, the direct calculation of the rainfall rates that will result in a given likelihood, and the ability to calculate spatially explicit rainfall intensity-duration thresholds for debris-flow generation in recently

Blood Flow: Multi-scale Modeling and Visualization (July 2011)

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

None

2011-01-01

Multi-scale modeling of arterial blood flow can shed light on the interaction between events happening at micro- and meso-scales (i.e., adhesion of red blood cells to the arterial wall, clot formation) and at macro-scales (i.e., change in flow patterns due to the clot). Coupled numerical simulations of such multi-scale flow require state-of-the-art computers and algorithms, along with techniques for multi-scale visualizations. This animation presents early results of two studies used in the development of a multi-scale visualization methodology. The fisrt illustrates a flow of healthy (red) and diseased (blue) blood cells with a Dissipative Particle Dynamics (DPD) method. Each bloodmore » cell is represented by a mesh, small spheres show a sub-set of particles representing the blood plasma, while instantaneous streamlines and slices represent the ensemble average velocity. In the second we investigate the process of thrombus (blood clot) formation, which may be responsible for the rupture of aneurysms, by concentrating on the platelet blood cells, observing as they aggregate on the wall of an aneruysm. Simulation was performed on Kraken at the National Institute for Computational Sciences. Visualization was produced using resources of the Argonne Leadership Computing Facility at Argonne National Laboratory.« less

Molluscan evidence for early middle Miocene marine glaciation in southern Alaska

USGS Publications Warehouse

Marincovich, L.

1990-01-01

Profound cooling of Miocene marine climates in southern Alaska culminated in early middle Miocene coastal marine glaciation in the northeastern Gulf of Alaska. This climatic change resulted from interaction of the Yakutat terrane with southern Alaska beginning in late Oligocene time. The ensuing extreme uplift of the coastal Chugach and St. Elias Mountains resulted in progressive regional cooling that culminated in coastal marine glaciation beginning in the early middle Miocene (15-16 Ma) and continuing to the present. The counterclockwise flow of surface water from the frigid northeastern Gulf of Alaska resulted in a cold-temperate shallow-marine environment in the western Gulf of Alaska, as it does today. Ironically, dating of Gulf of Alaska marine glaciation as early middle Miocene is strongly reinforced by the presence of a few tropical and subtropical mollusks in western Gulf of Alaska faunas. Shallow-marine waters throughout the Gulf of Alaska were cold-temperate to cold in the early middle Miocene, when the world ocean was undergoing peak Neogene warming. -Author

Validating Cellular Automata Lava Flow Emplacement Algorithms with Standard Benchmarks

NASA Astrophysics Data System (ADS)

Richardson, J. A.; Connor, L.; Charbonnier, S. J.; Connor, C.; Gallant, E.

2015-12-01

A major existing need in assessing lava flow simulators is a common set of validation benchmark tests. We propose three levels of benchmarks which test model output against increasingly complex standards. First, imulated lava flows should be morphologically identical, given changes in parameter space that should be inconsequential, such as slope direction. Second, lava flows simulated in simple parameter spaces can be tested against analytical solutions or empirical relationships seen in Bingham fluids. For instance, a lava flow simulated on a flat surface should produce a circular outline. Third, lava flows simulated over real world topography can be compared to recent real world lava flows, such as those at Tolbachik, Russia, and Fogo, Cape Verde. Success or failure of emplacement algorithms in these validation benchmarks can be determined using a Bayesian approach, which directly tests the ability of an emplacement algorithm to correctly forecast lava inundation. Here we focus on two posterior metrics, P(A|B) and P(¬A|¬B), which describe the positive and negative predictive value of flow algorithms. This is an improvement on less direct statistics such as model sensitivity and the Jaccard fitness coefficient. We have performed these validation benchmarks on a new, modular lava flow emplacement simulator that we have developed. This simulator, which we call MOLASSES, follows a Cellular Automata (CA) method. The code is developed in several interchangeable modules, which enables quick modification of the distribution algorithm from cell locations to their neighbors. By assessing several different distribution schemes with the benchmark tests, we have improved the performance of MOLASSES to correctly match early stages of the 2012-3 Tolbachik Flow, Kamchakta Russia, to 80%. We also can evaluate model performance given uncertain input parameters using a Monte Carlo setup. This illuminates sensitivity to model uncertainty.

Cardiac and metabolic effects of chronic growth hormone and insulin-like growth factor I excess in young adults with pituitary gigantism.

PubMed

Bondanelli, Marta; Bonadonna, Stefania; Ambrosio, Maria Rosaria; Doga, Mauro; Gola, Monica; Onofri, Alessandro; Zatelli, Maria Chiara; Giustina, Andrea; degli Uberti, Ettore C

2005-09-01

Chronic growth hormone (GH)/insulin-like growth factor I (IGF-I) excess is associated with considerable mortality in acromegaly, but no data are available in pituitary gigantism. The aim of the study was to evaluate the long-term effects of early exposure to GH and IGF-I excess on cardiovascular and metabolic parameters in adult patients with pituitary gigantism. Six adult male patients with newly diagnosed gigantism due to GH secreting pituitary adenoma were studied and compared with 6 age- and sex-matched patients with acromegaly and 10 healthy subjects. Morphologic and functional cardiac parameters were evaluated by Doppler echocardiography. Glucose metabolism was assessed by evaluating glucose tolerance and homeostasis model assessment index. Disease duration was significantly longer (P<.05) in patients with gigantism than in patients with acromegaly, whereas GH and IGF-I concentrations were comparable. Left ventricular mass was increased both in patients with gigantism and in patients with acromegaly, as compared with controls. Left ventricular hypertrophy was detected in 2 of 6 of both patients with gigantism and patients with acromegaly, and isolated intraventricular septum thickening in 1 patient with gigantism. Inadequate diastolic filling (ratio between early and late transmitral flow velocity<1) was detected in 2 of 6 patients with gigantism and 1 of 6 patients with acromegaly. Impaired glucose metabolism occurrence was higher in patients with acromegaly (66%) compared with patients with gigantism (16%). Concentrations of IGF-I were significantly (P<.05) higher in patients with gigantism who have cardiac abnormalities than in those without cardiac abnormalities. In conclusion, our data suggest that GH/IGF-I excess in young adult patients is associated with morphologic and functional cardiac abnormalities that are similar in patients with gigantism and in patients with acromegaly, whereas occurrence of impaired glucose metabolism appears to be higher in

Association of Central Sleep Apnea with Impaired Heart Structure and Cardiovascular Hemodynamics in Patients with Chronic Heart Failure

PubMed Central

Kazimierczak, Anna; Krzesiński, Paweł; Gielerak, Grzegorz; Uziebło-Życzkowska, Beata; Smurzyński, Paweł; Ryczek, Robert; Cwetsch, Andrzej; Skrobowski, Andrzej

2016-01-01

Background Advanced heart failure (HF) is commonly accompanied by central sleep apnea (CSA) with Cheyne-Stokes respiration (CSR). The aim of this study was to evaluate the relationship between CSA/CSR and other clinical features of HF, with particular emphasis on cardiovascular hemodynamics. Material/Methods In 161 stable HF patients with left ventricular ejection fraction (LVEF) ≤45% (NYHA class I–III; mean LVEF 32.8%) the clinical evaluation included: LVEF; left and right ventricular end-diastolic diameter (LVDd, RVDd); ratio of early transmitral flow velocity to early diastolic septal mitral annulus velocity (E/e’) assessed by echocardiography; stroke index (SI); heart rate (HR); cardiac index (CI); and systemic vascular resistance index (SVRI) assessed by impedance cardiography (ICG). The comparison was performed between 2 subgroups: one with moderate/severe CSA/CSR - CSR_ [+] (n=51), and one with mild or no CSA/CSR – CSR_ [−] (n=110). Results CSR_ [+] patients presented more advanced NYHA class (p<0.001) and more frequently had permanent atrial fibrillation (p=0.018). Moreover, they had: lower LVEF (p<0.0001); higher LVDd (p<0.0001), RVDd (p<0.001), and E/e’ (p<0.001); lower SI (p<0.001) and CI (p=0.009); and higher HR (p=0.044) and SVRI (p=0.016). The following predictors of CSR_ [+] were identified: NYHA class (OR=3.34 per class, p<0.001, which was the only independent predictor); atrial fibrillation (OR=2.29, p=0.019); RV enlargement (OR=2.75, p=0.005); LVEF<35% (OR=3.38, p=0.001); E/e’ (OR=3.15; p=0.003); and SI<35 ml/m2 (OR=2.96, p=0.003). Conclusions Presence of CSA/CSR in HF is associated with NYHA class, atrial fibrillation and more advanced impairment of cardiovascular structure and hemodynamics. Patient functional state remains the main determinant of CSR. PMID:27558771

Characterising Atlantic deep waters during the extreme warmth of the early Eocene 'greenhouse'.

NASA Astrophysics Data System (ADS)

Cameron, A.; Sexton, P. F.; Anand, P.; Huck, C. E.; Fehr, M.; Dickson, A.; Scher, H. D.; van de Flierdt, T.; Westerhold, T.; Roehl, U.

2014-12-01

The meridional overturning circulation (MOC) is a planetary-scale oceanic flow that is of direct importance to the climate system because it transports heat, salt and nutrients to high latitudes and regulates the exchange of CO2 with the atmosphere. The Atlantic Ocean plays a strong role in the modern day MOC however, it is unclear what role it may have played during extreme climate conditions such as those found in the early Eocene 'greenhouse'. In order to resolve the Atlantic's role in the MOC during the early/middle Eocene, we present a multi-proxy approach to investigate changes in ocean circulation, water mass geometry, sediment supply to the deep oceans and the physical strength of deep waters from four different IODP drill sites. Neodymium isotopes (ɛNd), REE profiles and cerium anomalies measured in fossilised fish teeth help to characterise geochemical changes to water masses throughout the Atlantic whilst bulk sediment ɛNd and XRF-core scan data documents changes in sediment supply to the region. Sortable silt data provides a physical constraint on the strength of deep-water movements during the extreme climatic conditions of the early Eocene. We utilise expanded and continuous sequences from two sites in the North west Atlantic spanning the early to middle Eocene recently recovered on IODP Exp. 342 (1403, 1409) that are located on the Newfoundland Ridge, directly in the flow path of today's Deep Western Boundary Current. We also present data from equatorial Demerara Rise (IODP site 1258) and from further north at the mouth of the Labrador Sea (ODP Site 647).

B-Flow Imaging in Lower Limb Peripheral Arterial Disease and Bypass Graft Ultrasonography.

PubMed

D'Abate, Fabrizio; Ramachandran, Veni; Young, Mark A; Farrah, John; Ahmed, Mudasar H; Jones, Keith; Hinchliffe, Robert J

2016-09-01

Doppler ultrasonography plays a key role in the diagnosis of peripheral arterial disease, but is often limited by pitfalls that may be overcome by B-flow imaging. Thus far, there is little information on B-flow imaging for the assessment of peripheral arterial disease and bypass grafts in lower limbs. This article describes the authors' early experience with B-flow in the lower extremities. Sixty patients were included among a large cohort of patients routinely referred to the vascular laboratory for peripheral arterial disease and bypass graft assessments. Two experienced vascular sonographers performed all scans, comparing color Doppler ultrasonography with B-flow imaging. All scans were performed using a combination of the 9 L linear and C2-9 curvilinear transducers with the LOGIQ E9 system (GE Healthcare, Waukesha, WI, USA). Our experience indicates that this relatively unexplored technology has the potential to significantly improve peripheral blood flow evaluation. Nevertheless, B-flow imaging is not exempt from limitations and should be considered complementary to color Doppler ultrasonography. Copyright © 2016 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

Cardiac Amyloidosis Shows Decreased Diastolic Function as Assessed by Echocardiographic Parameterized Diastolic Filling.

PubMed

Salman, Katrin; Cain, Peter A; Fitzgerald, Benjamin T; Sundqvist, Martin G; Ugander, Martin

2017-07-01

Cardiac amyloidosis is a rare but serious condition with poor survival. One of the early findings by echocardiography is impaired diastolic function, even before the development of cardiac symptoms. Early diagnosis is important, permitting initiation of treatment aimed at improving survival. The parameterized diastolic filling (PDF) formalism entails describing the left ventricular filling pattern during early diastole using the mathematical equation for the motion of a damped harmonic oscillator. We hypothesized that echocardiographic PDF analysis could detect differences in diastolic function between patients with amyloidosis and controls. Pulsed-wave Doppler echocardiography of transmitral flow was measured in 13 patients with amyloid heart disease and 13 age- and gender matched controls. E- waves (2 to 3 per subject) were analyzed using in-house developed software. Nine PDF-derived parameters were obtained in addition to conventional echocardiographic parameters of diastolic function. Compared to controls, cardiac amyloidosis patients had a larger left atrial area (23.7 ± 7.5 cm 2 vs. 18.5 ± 4.8 cm 2 , p = 0.04), greater interventricular septum wall thickness (14.4 ± 2.6 mm vs. 9.3 ± 1.3 mm, p < 0.001), lower e' (0.06 ± 0.02 m/s vs. 0.09 ± 0.02 m/s, p < 0.001) and higher E/e' (18.0 ± 12.9 vs. 7.7 ± 1.3, p = 0.001). The PDF parameter peak resistive force was greater in cardiac amyloidosis patients compared to controls (17.9 ± 5.7 mN vs. 13.1 ± 3.1 mN, p = 0.03), and other PDF parameters did not differ. PDF analysis revealed that patients with cardiac amyloidosis had a greater peak resistive force compared to controls, consistent with a greater degree of diastolic dysfunction. PDF analysis may be useful in characterizing diastolic function in amyloid heart disease. Copyright © 2017 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

Pool and flow boiling in variable and microgravity

NASA Technical Reports Server (NTRS)

Merte, Herman, Jr.

1994-01-01

As is well known, boiling is an effective mode of heat transfer in that high heat flux levels are possible with relatively small temperature differences. Its optimal application requires that the process be adequately understood. A measure of the understanding of any physical event lies in the ability to predict its behavior in terms of the relevant parameters. Despite many years of research the predictability of boiling is currently possible only for quite specialized circumstances, e.g., the critical heat flux and film boiling for the pool boiling case, and then only with special geometries. Variable gravity down to microgravity provides the opportunity to test this understanding, but possibly more important, by changing the dimensional and time scales involved permits more detailed observations of elements involved in the boiling process, and perhaps discloses phenomena heretofore unknown. The focus here is on nucleate boiling although, as will be demonstrated below, under but certain circumstances in microgravity it can take place concurrently with the dryout process. In the presence of earth gravity or forced convection effects, the latter process is usually referred to as film boiling. However, no vapor film as such forms with pool boiling in microgravity, only dryout. Initial results are presented here for pool boiling in microgravity, and were made possible at such an early date by the availability of the Get-Away-Specials (GAS). Also presented here are some results of ground testing of a flow loop for the study of low velocity boiling, eventually to take place also in microgravity. In the interim, variable buoyancy normal to the heater surface is achieved by rotation of the entire loop relative to earth gravity. Of course, this is at the expense of varying the buoyancy parallel to the heater surface. Two questions which must be resolved early in the study of flow boiling in microgravity are (1) the lower limits of liquid flow velocity where buoyancy

Flow structure in continuous flow electrophoresis chambers

NASA Technical Reports Server (NTRS)

Deiber, J. A.; Saville, D. A.

1982-01-01

There are at least two ways that hydrodynamic processes can limit continiuous flow electrophoresis. One arises from the sensitivity of the flow to small temerature gradients, especially at low flow rates and power levels. This sensitivity can be suppressed, at least in principle, by providing a carefully tailored, stabilizing temperature gradient in the cooling system that surrounds the flow channel. At higher power levels another limitation arises due to a restructuring of the main flow. This restructuring is caused by buoyancy, which is in turn affected by the electro-osmotic crossflow. Approximate solutions to appropriate partial differential equations have been computed by finite difference methods. One set of results is described here to illustrate the strong coupling between the structure of the main (axial) flow and the electro-osmotic flow.

Lateral Flow Rapid Test for Accurate and Early Diagnosis of Scrub Typhus: A Febrile Illness of Historically Military Importance in the Pacific Rim.

PubMed

Chao, Chien-Chung; Zhangm, Zhiwen; Weissenberger, Giulia; Chen, Hua-Wei; Ching, Wei-Mei

2017-03-01

Scrub typhus (ST) is an infection caused by Orientia tsutsugamushi. Historically, ST was ranked as the second most important arthropod-borne medical problem only behind malaria during World War II and the Vietnam War. The disease occurs mainly in Southeast Asia and has been shown to emerge and reemerge in new areas, implying the increased risk for U.S. military and civilian personnel deployed to these regions. ST can effectively be treated by doxycycline provided the diagnosis is made early, before the development of severe complications. Scrub Typhus Detect is a lateral flow rapid test based on a mixture of recombinant 56-kDa antigens with broad reactivity. The performance of this prototype product was evaluated against indirect immunofluorescence assay, the serological gold standard. Using 249 prospectively collected samples from Thailand, the sensitivity and specificity for IgM was found to be 100% and 92%, respectively, suggesting a high potential of this product for clinical use. This product will provide a user friendly, rapid, and accurate diagnosis of ST for clinicians to provide timely and accurate treatments of deployed personnel. Reprint & Copyright © 2017 Association of Military Surgeons of the U.S.

Functional test of pedotransfer functions to predict water flow and solute transport with the dual-permeability model MACRO

NASA Astrophysics Data System (ADS)

Moeys, J.; Larsbo, M.; Bergström, L.; Brown, C. D.; Coquet, Y.; Jarvis, N. J.

2012-07-01

Estimating pesticide leaching risks at the regional scale requires the ability to completely parameterise a pesticide fate model using only survey data, such as soil and land-use maps. Such parameterisations usually rely on a set of lookup tables and (pedo)transfer functions, relating elementary soil and site properties to model parameters. The aim of this paper is to describe and test a complete set of parameter estimation algorithms developed for the pesticide fate model MACRO, which accounts for preferential flow in soil macropores. We used tracer monitoring data from 16 lysimeter studies, carried out in three European countries, to evaluate the ability of MACRO and this "blind parameterisation" scheme to reproduce measured solute leaching at the base of each lysimeter. We focused on the prediction of early tracer breakthrough due to preferential flow, because this is critical for pesticide leaching. We then calibrated a selected number of parameters in order to assess to what extent the prediction of water and solute leaching could be improved. Our results show that water flow was generally reasonably well predicted (median model efficiency, ME, of 0.42). Although the general pattern of solute leaching was reproduced well by the model, the overall model efficiency was low (median ME = -0.26) due to errors in the timing and magnitude of some peaks. Preferential solute leaching at early pore volumes was also systematically underestimated. Nonetheless, the ranking of soils according to solute loads at early pore volumes was reasonably well estimated (concordance correlation coefficient, CCC, between 0.54 and 0.72). Moreover, we also found that ignoring macropore flow leads to a significant deterioration in the ability of the model to reproduce the observed leaching pattern, and especially the early breakthrough in some soils. Finally, the calibration procedure showed that improving the estimation of solute transport parameters is probably more important than the

Transition of a Three-Dimensional Unsteady Viscous Flow Analysis from a Research Environment to the Design Environment

NASA Technical Reports Server (NTRS)

Dorney, Suzanne; Dorney, Daniel J.; Huber, Frank; Sheffler, David A.; Turner, James E. (Technical Monitor)

2001-01-01

The advent of advanced computer architectures and parallel computing have led to a revolutionary change in the design process for turbomachinery components. Two- and three-dimensional steady-state computational flow procedures are now routinely used in the early stages of design. Unsteady flow analyses, however, are just beginning to be incorporated into design systems. This paper outlines the transition of a three-dimensional unsteady viscous flow analysis from the research environment into the design environment. The test case used to demonstrate the analysis is the full turbine system (high-pressure turbine, inter-turbine duct and low-pressure turbine) from an advanced turboprop engine.

Quantity and sources of base flow in the San Pedro River near Tombstone, Arizona

USGS Publications Warehouse

Kennedy, Jeffrey R.; Gungle, Bruce

2010-01-01

possible upstream of the Tombstone gaging station. Because of losing conditions upstream of the Tombstone gage, there is no minimum amount of base flow that would be expected in any given year. The regression equation was used to adjust the measured base flow to account for year-to-year variation in precipitation. Adjusted base flows decreased, independent of climate, from the early period of record to the late period of record. In addition to total base flow, other metrics were considered, including the start and end dates of base flow, the number of days of base flow, the 25th percentile mean daily flow, and the number of days of zero flow. Each of these showed a decline in base flow between the early period of record and the late period. The available evidence to evaluate this decrease - hydraulic gradients in the alluvial and regional aquifers and a 10-yr record of streamflow environmental isotope samples - indicates that no reduction in groundwater discharge has occurred over this period of record. Continued regional groundwater pumping will, however, eventually lead to a decline in the contribution of regional groundwater to base flow.

Three-Dimensional Upward Flame Spreading in Partial-Gravity Buoyant Flows

NASA Technical Reports Server (NTRS)

Sacksteder, Kurt R.; Feier, Ioan I.; Shih, Hsin-Yi; T'ien, James S.

2001-01-01

Reduced-gravity environments have been used to establish low-speed, purely forced flows for both opposed- and concurrent-flow flame spread studies. Altenkirch's group obtained spacebased experimental results and developed unsteady, two-dimensional numerical simulations of opposed-flow flame spread including gas-phase radiation, primarily away from the flammability limit for thin fuels, but including observations of thick fuel quenching in quiescent environments. T'ien's group contributed some early flame spreading results for thin fuels both in opposed flow and concurrent flow regimes, with more focus on near-limit conditions. T'ien's group also developed two- and three-dimensional numerical simulations of concurrent-flow flame spread incorporating gas-phase radiative models, including predictions of a radiatively-induced quenching limit reached in very low-speed air flows. Radiative quenching has been subsequently observed in other studies of combustion in very low-speed flows including other flame spread investigations, droplet combustion and homogeneous diffusion flames, and is the subject of several contemporary studies reported in this workshop. Using NASA aircraft flying partial-gravity "parabolic" trajectories, flame spreading in purely buoyant, opposed-flow (downward burning) has been studied. These results indicated increases in flame spread rates and enhanced flammability (lower limiting atmospheric oxygen content) as gravity levels were reduced from normal Earth gravity, and were consistent with earlier data obtained by Altenkirch using a centrifuge. In this work, experimental results and a three-dimensional numerical simulation of upward flame spreading in variable partial-gravity environments were obtained including some effects of reduced pressure and variable sample width. The simulation provides physical insight for interpreting the experimental results and shows the intrinsic 3-D nature of buoyant, upward flame spreading. This study is intended to

Heat flow and thermal history of the Anadarko basin, Oklahoma

USGS Publications Warehouse

Carter, L.S.; Kelley, S.A.; Blackwell, D.D.; Naeser, N.D.

1998-01-01

New heat-flow values for seven sites in the Anadarko basin, Oklahoma, were determined using high-precision temperature logs and thermal conductivity measurements from nearly 300 core plugs. Three of the sites are on the northern shelf, three sites are in the deep basin, and one site is in the frontal fault zone of the northern Wichita Mountains. The heat flow decreased from 55 to 64 mW/m2 in the north, and from 39 to 54 mW/m2 in the south, due to a decrease in heat generation in the underlying basement rock toward the south. Lateral lithologic changes in the basin, combined with the change in heat flow across the basin, resulted in an unusual pattern of thermal maturity. The vitrinite reflectance values of the Upper Devonian-Lower Mississippian Woodford formation are highest 30-40 km north-northwest of the deepest part of the basin. The offset in highest reflectance values is due to the contrast in thermal conductivity between the Pennsylvanian "granite wash" section adjacent to the Wichita uplift and the Pennsylvanian shale section to the north. The geothermal gradient in the low-conductivity shale section is elevated relative to the geothermal gradient in the high-conductivity "granite wash" section, thus displacing the highest temperatures to the north of the deepest part of the basin. Apatite fission-track, vitrinite reflectance, and heat-flow data were used to constrain regional aspects of the burial history of the Anadarko basin. By combining these data sets, we infer that at least 1.5 km of denudation has occurred at two sites in the deep Anadarko basin since the early to middle Cenozoic (40 ?? 10 m.y.). The timing of the onset of denudation in the southern Anadarko basin coincides with the period of late Eocene erosion observed in the southern Rocky Mountains and in the northern Great Plains. Burial history models for two wells from the deep Anadarko basin predict that shales of the Woodford formation passed through the hydrocarbon maturity window by the

Bulk flow in the combined 2MTF and 6dFGSv surveys

NASA Astrophysics Data System (ADS)

Qin, Fei; Howlett, Cullan; Staveley-Smith, Lister; Hong, Tao

2018-07-01

We create a combined sample of 10 904 late- and early-type galaxies from the 2MTF and 6dFGSv surveys in order to accurately measure bulk flow in the local Universe. Galaxies and groups of galaxies common between the two surveys are used to verify that the difference in zero-points is <0.02 dex. We introduce a maximum likelihood estimator (ηMLE) for bulk flow measurements that allows for more accurate measurement in the presence of non-Gaussian measurement errors. To calibrate out residual biases due to the subtle interaction of selection effects, Malmquist bias and anisotropic sky distribution, the estimator is tested on mock catalogues generated from 16 independent large-scale GiggleZ and SURFS simulations. The bulk flow of the local Universe using the combined data set, corresponding to a scale size of 40 h-1 Mpc, is 288 ± 24 km s-1 in the direction (l, b) = (296 ± 6°, 21 ± 5°). This is the most accurate bulk flow measurement to date, and the amplitude of the flow is consistent with the Λ cold dark matter expectation for similar size scales.

Bulk flow in the combined 2MTF and 6dFGSv surveys

NASA Astrophysics Data System (ADS)

Qin, Fei; Howlett, Cullan; Staveley-Smith, Lister; Hong, Tao

2018-04-01

We create a combined sample of 10,904 late and early-type galaxies from the 2MTF and 6dFGSv surveys in order to accurately measure bulk flow in the local Universe. Galaxies and groups of galaxies common between the two surveys are used to verify that the difference in zero-points is <0.02 dex. We introduce a new maximum likelihood estimator (ηMLE) for bulk flow measurements which allows for more accurate measurement in the presence non-Gaussian measurement errors. To calibrate out residual biases due to the subtle interaction of selection effects, Malmquist bias and anisotropic sky distribution, the estimator is tested on mock catalogues generated from 16 independent large-scale GiggleZ and SURFS simulations. The bulk flow of the local Universe using the combined data set, corresponding to a scale size of 40 h-1 Mpc, is 288 ± 24 km s-1 in the direction (l, b) = (296 ± 6°, 21 ± 5°). This is the most accurate bulk flow measurement to date, and the amplitude of the flow is consistent with the ΛCDM expectation for similar size scales.

Exquisite Moments: Achieving Optimal Flow in Three Activity-Based Groups Regardless of Early-Childhood Adversity

ERIC Educational Resources Information Center

Thomson, Paula; Jaque, S. Victoria

2016-01-01

Flow experiences (also known as optimal performance) occur when people engage in activities they enjoy. The authors discuss such events in their study that examined a number of healthy, active individuals (performing artists, athletes, and others engaged in a range of recreational activities) and divided these into three groups based on adverse…

Ebb and Flow in Parent-Child Interactions: Shifts from Early through Middle Childhood

PubMed Central

Bradley, Robert H.; Pennar, Amy; Iida, Masumi

2015-01-01

Objective This study documents the strength of relations between key parent and child behaviors as they occur during typical encounters for both mothers and fathers and determines whether there were shifts in the strength of relations between parent and child behaviors during early and middle childhood. Design Multivariate multi-level modeling was used to examine associations between three parent behaviors (respect for autonomy, stimulation of development, hostility) and two child behaviors (agency, negativity) as they occurred in typical parent-child activities at four time points from 54 months through 5th grade for 817 families. Results For mothers and fathers, respect for autonomy and stimulation were associated with child agency. Paternal hostility was negatively associated with child agency, but for mothers the relation became more positive with age. Parental respect for autonomy and hostility were associated with child negativity for both mothers and fathers; however, for mothers, relations between autonomy support and child negativity became more positive, and relations between hostility and child negativity became less positive. Conclusions There are clear shifts in the strength of relations between some parenting behaviors and child behaviors from early to middle childhood, indicative of a changing dialectic as children become more independent and different dialectics for mothers and fathers. Parenting behavior links to child competence and adaptive behavior, and the findings may help resolve some uncertainties about relations between parental behavior and children's developmental trajectories. PMID:26877717

Interstellar Gas Flow Vector and Temperature Determination over 5 Years of IBEX Observations

NASA Astrophysics Data System (ADS)

Möbius, E.; Bzowski, M.; Fuselier, S. A.; Heirtzler, D.; Kubiak, M. A.; Kucharek, H.; Lee, M. A.; Leonard, T.; McComas, D. J.; Schwadron, N.; Sokół, J. M.; Wurz, P.

2015-01-01

The Interstellar Boundary Explorer (IBEX) observes the interstellar neutral gas flow trajectories at their perihelion in Earth's orbit every year from December through early April, when the Earth's orbital motion is into the oncoming flow. These observations have defined a narrow region of possible, but very tightly coupled interstellar neutral flow parameters, with inflow speed, latitude, and temperature as well-defined functions of inflow longitude. The best- fit flow vector is different by ≈ 3° and lower by ≈ 3 km/s than obtained previously with Ulysses GAS, but the temperature is comparable. The possible coupled parameter space reaches to the previous flow vector, but only for a substantially higher temperature (by ≈ 2000 K). Along with recent pickup ion observations and including historical observations of the interstellar gas, these findings have led to a discussion, whether the interstellar gas flow into the solar system has been stable or variable over time. These intriguing possibilities call for more detailed analysis and a longer database. IBEX has accumulated observations over six interstellar flow seasons. We review key observations and refinements in the analysis, in particular, towards narrowing the uncertainties in the temperature determination. We also address ongoing attempts to optimize the flow vector determination through varying the IBEX spacecraft pointing and discuss related implications for the local interstellar cloud and its interaction with the heliosphere.

Embolisation of the Gastroduodenal Artery is Not Necessary in the Presence of Reversed Flow Before Yttrium-90 Radioembolisation

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

Daghir, Ahmed A., E-mail: ahmeddaghir@doctors.net.uk; Gungor, Hatice; Haydar, Ali A.

2012-08-15

Introduction: The gastroduodenal artery (GDA) is usually embolised to avoid nontarget dispersal before yttrium-90 (Y{sup 90}) radioembolisation to treat liver metastases. In a minority of patients, there is retrograde flow in the GDA. The purpose of this study was to determine if there is any increased risk from maintaining a patent GDA in patients with reversed flow. Materials and Methods: A retrospective review was performed of all patients undergoing Y{sup 90} radioembolisation at our institution. The incidence of toxicities arising from nontarget radioembolisation by way of the GDA (gastric/duodenal ulceration, gastric/duodenal bleeding, and pancreatitis) and death occurring within 2 monthsmore » of treatment were compared between the reversed and the antegrade GDA groups. Results: Ninety-two patients underwent preliminary angiography. Reversed GDA flow was found on angiography in 14.1% of cases; the GDA was not embolised in these patients. The GDA was coiled in 55.7% of patients with antegrade GDA flow to prevent inadvertent dispersal of radioembolic material. There was no increased toxicity related to nontarget dispersal by way of the GDA, or increased early mortality, in patients with reversed GDA flow (P > 0.05). Conclusion: In patients with reversed GDA flow, maintenance of a patent GDA before administration of Y{sup 90} radioembolisation does not increase the risk of toxicity from nontarget dispersal. Therapeutic injection, with careful monitoring to identify early vascular stasis, may be safely performed beyond the origin of the patent GDA. A patent GDA with reversed flow provides forward drive for infused particles and may allow alternative access to the hepatic circulation.« less

Visualization of Pulmonary Clearance Mechanisms via Noninvasive Optical Imaging Validated by Near-Infrared Flow Cytometry

PubMed Central

Zhou, Haiying; Gunsten, Sean P.; Zhegalova, Natalia G.; Bloch, Sharon; Achilefu, Samuel; Holley, J. Christopher; Schweppe, Daniel; Akers, Walter; Brody, Steven L.; Eades, William; Berezin, Mikhail Y.

2016-01-01

In vivo optical imaging with near-infrared (NIR) probes is an established method of diagnostics in preclinical and clinical studies. However, the specificities of these probes are difficult to validate ex vivo due to the lack of NIR flow cytometry. To address this limitation, we modified a flow cytometer to include an additional NIR channel using a 752 nm laser line. The flow cytometry system was tested using NIR microspheres and cell lines labeled with a combination of visible range and NIR fluorescent dyes. The approach was verified in vivo in mice evaluated for immune response in lungs after intratracheal delivery of the NIR contrast agent. Flow cytometry of cells obtained from the lung bronchoalveolar lavage demonstrated that the NIR dye was taken up by pulmonary macrophages as early as four-hours post-injection. This combination of optical imaging with NIR flow cytometry extends the capability of imaging and enables complementation of in vivo imaging with cell-specific studies. PMID:25808737

Blood flow changes using a 3D xenogeneic collagen matrix or a subepithelial connective tissue graft for root coverage procedures: a pilot study.

PubMed

Tatarakis, Nikolaos; Gkranias, Nikolaos; Darbar, Ulpee; Donos, Nikolaos

2018-05-01

The study investigated the early healing process following the treatment of single Miller class I and II recessions with a 3D xenogeneic collagen matrix (CMX) or connective tissue graft (CTG). This pilot investigation was designed as a single-center randomized controlled parallel trial. A total of eight subjects (four per group) were treated with either CMX or CTG in the anterior maxilla. Vascular flow changes were assessed by laser Doppler flowmetry (LDF) before and after surgery and at days 1, 2, 3, 7, 14, and 30 while clinical evaluations took place at baseline and at days 60 and 180. Pain intensity perception was evaluated by the short-form McGill pain questionnaire (SF-MPQ), at days 1 and 14. The vascular flow fluctuated similarly in both groups pre- and post-operatively, but the CTG exhibited a more homogeneous pattern as opposed to CMX that showed a second phase of increased blood flow at 14 days. Clinically, the CTG led to greater change in mean root coverage and keratinized tissue gain but CMX was associated with lower early pain intensity scores. Within the limits of the study, the vascular flow alterations during the early healing of both graft types followed a similar pattern. The CMX was associated with a second peak of increased blood flow. The vascular flow changes after the application of CMX for single tooth recession root coverage did not show major differences from those observed after the use of a CTG. A trend for better clinical performance in terms of root coverage and keratinized tissue gain was noted for the CTG, but the initial patient morbidity was less for CMX.

Accomplishing the genotype-specific serodiagnosis of single and dual Trypanosoma cruzi infections by flow cytometry Chagas-Flow ATE-IgG2a

PubMed Central

Alessio, Glaucia Diniz; de Araújo, Fernanda Fortes; Sales Júnior, Policarpo Ademar; Gomes, Matheus de Souza; do Amaral, Laurence Rodrigues; Pascoal Xavier, Marcelo Antônio; Teixeira-Carvalho, Andréa; de Lana, Marta

2018-01-01

The methods currently available for genotype-specific diagnosis of T. cruzi infection still present relevant limitations, especially to identify mixed infection. In the present investigation, we have evaluated the performance of Chagas-Flow ATE-IgG2a test for early and late differential diagnosis of single and dual genotype-specific T. cruzi infections. Serum samples from Swiss mice at early and late stages of T. cruzi infection were assayed in parallel batches for genotype-specific diagnosis of single (TcI, TcVI or TcII) and dual (TcI+TcVI, TcVI+TcII or TcII+TcI) infections. The intrinsic reactivity to TcI, TcVI and TcII target antigens, including amastigote (AI/AVI/AII), trypomastigote-(TI/TVI/TII) and epimastigote (EI/EVI/EII), at specific reverse of serum dilutions (500 to 64,000), was employed to provide reliable decision-trees for “early” vs “late”, “single vs “dual” and “genotype-specific” serology. The results demonstrated that selective set of attributes “EII 500/EI 2,000/AII 500” were able to provide high-quality accuracy (81%) to segregate early and late stages of T. cruzi infection. The sets “TI 2,000/AI 1,000/EII 1,000” and “TI 8,000/AII 32,000” presented expressive scores to discriminate single from dual T. cruzi infections at early (85%) and late stages (84%), respectively. Moreover, the attributes “TI 4,000/TVI 500/TII 1,000”, “TI 16,000/EI 2,000/EII 2,000/AI 500/TVI 500” showed good performance for genotype-specific diagnosis at early stage of single (72%) and dual (80%) T. cruzi infections, respectively. In addition, the attributes “TI 4,000/AII 1,000/EVI 1,000”, “TI 64,000/AVI 500/AI 2,000/AII 1,000/EII 4,000” showed moderate performance for genotype-specific diagnosis at late stage of single (69%) and dual (76%) T. cruzi infections, respectively. The sets of decision-trees were assembled to construct a sequential algorithm with expressive accuracy (81%) for serological diagnosis of T. cruzi infection

Positron Emission Tomography-Determined Hyperemic Flow, Myocardial Flow Reserve, and Flow Gradient—Quo Vadis?

PubMed Central

Leucker, Thorsten M.; Valenta, Ines; Schindler, Thomas Hellmut

2017-01-01

Positron emission tomography/computed tomography (PET/CT) applied with positron-emitting flow tracers such as 13N-ammonia and 82Rubidium enables the quantification of both myocardial perfusion and myocardial blood flow (MBF) in milliliters per gram per minute for coronary artery disease (CAD) detection and characterization. The detection of a regional myocardial perfusion defect during vasomotor stress commonly identifies the culprit lesion or most severe epicardial narrowing, whereas adding regional hyperemic MBFs, myocardial flow reserve (MFR), and/or longitudinal flow decrease may also signify less severe but flow-limiting stenosis in multivessel CAD. The addition of regional hyperemic flow parameters, therefore, may afford a comprehensive identification and characterization of flow-limiting effects of multivessel CAD. The non-specific origin of decreases in hyperemic MBFs and MFR, however, prompts an evaluation and interpretation of regional flow in the appropriate context with the presence of obstructive CAD. Conversely, initial results of the assessment of a longitudinal hyperemic flow gradient suggest this novel flow parameter to be specifically related to increases in CAD caused epicardial resistance. The concurrent assessment of myocardial perfusion and several hyperemic flow parameters with PET/CT may indeed open novel avenues of precision medicine to guide coronary revascularization procedures that may potentially lead to a further improvement in cardiovascular outcomes in CAD patients. PMID:28770213

Locomotion of bacteria in liquid flow and the boundary layer effect on bacterial attachment

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

Zhang, Chao, E-mail: zhangchao@cqu.edu.cn; Institute of Engineering Thermophysics, Chongqing University, Chongqing 400030; Liao, Qiang, E-mail: lqzx@cqu.edu.cn

The formation of biofilm greatly affects the performance of biological reactors, which highly depends on bacterial swimming and attachment that usually takes place in liquid flow. Therefore, bacterial swimming and attachment on flat and circular surfaces with the consideration of flow was studied experimentally. Besides, a mathematical model comprehensively combining bacterial swimming and motion with flow is proposed for the simulation of bacterial locomotion and attachment in flow. Both experimental and theoretical results revealed that attached bacteria density increases with decreasing boundary layer thickness on both flat and circular surfaces, the consequence of which is inherently related to the competitionmore » between bacterial swimming and the non-slip motion with flow evaluated by the Péclet number. In the boundary layer, where the Péclet number is relatively higher, bacterial locomotion mainly depends on bacterial swimming. Thinner boundary layer promotes bacterial swimming towards the surface, leading to higher attachment density. To enhance the performance of biofilm reactors, it is effective to reduce the boundary layer thickness on desired surfaces. - Highlights: • Study of bacterial locomotion in flow as an early stage in biofilm formation. • Mathematical model combining bacterial swimming and the motion with flow. • Boundary layer plays a key role in bacterial attachment under flow condition. • The competition between bacterial swimming and the motion with flow is evaluated.« less

Early bronchopulmonary involvement in Crohn disease: a case report

PubMed Central

Valletta, Enrico; Bertini, Marina; Sette, Luciano; Braggion, Cesare; Pradal, Ugo; Zannoni, Marina

2001-01-01

Background Bronchopulmonary manifestations of Crohn disease have been rarely described in children, including both subclinical pulmonary involvement and severe lung disease. Case presentation A 6.5-year-old girl is described with early recurrent bronchopulmonary symptoms both at presentation and in the quiescent phase of Crohn disease. Pulmonary function tests (lung volumes and flows, bronchial reactivity and carbon monoxide diffusing capacity) were normal. Bronchoalveolar cytology showed increased (30%) lymphocyte counts and bronchial biopsy revealed thickening of basal membrane and active chronic inflammation. Conclusions Clinical and histological findings in our young patient suggest involvement of both distal and central airways in an early phase of lung disease. The pathogenesis of Crohn disease-associated lung disorders is discussed with reference to the available literature. A low threshold for pulmonary evaluation seems to be advisable in all children with CD. PMID:11734067

Early miocene bimodal volcanism, Northern Wilson Creek Range, Lincoln County, Nevada

USGS Publications Warehouse

Willis, J.B.; Willis, G.C.

1996-01-01

Early Miocene volcanism in the northern Wilson Creek Range, Lincoln County, Nevada, produced an interfingered sequence of high-silica rhyolite (greater than 74% SiO2) ash-flow tuffs, lava flows and dikes, and mafic lava flows. Three new potassium-argon ages range from 23.9 ?? 1.0 Ma to 22.6 ?? 1.2 Ma. The rocks are similar in composition, stratigraphic character, and age to the Blawn Formation, which is found in ranges to the east and southeast in Utah, and, therefore, are herein established as a western extension of the Blawn Formation. Miocene volcanism in the northern Wilson Creek Range began with the eruption of two geochemically similar, weakly evolved ash-flow tuff cooling units. The lower unit consists of crystal-poor, loosely welded, lapilli ash-flow tuffs, herein called the tuff member of Atlanta Summit. The upper unit consists of homogeneous, crystal-rich, moderately to densely welded ash-flow tuffs, herein called the tuff member of Rosencrans Peak. This unit is as much as 300 m thick and has a minimum eruptive volume of 6.5 km3, which is unusually voluminous for tuffs in the Blawn Formation. Thick, conspicuously flow-layered rhyolite lava flows were erupted penecontemporaneously with the tuffs. The rhyolite lava flows have a range of incompatible trace element concentrations, and some of them show an unusual mixing of aphyric and porphyritic magma. Small volumes of alkaline, vesicular, mafic flows containing 50 weight percent SiO2 and 2.3 weight percent K2O were extruded near the end of the rhyolite volcanic activity. The Blawn Formation records a shift in eruptive style and magmatic composition in the northern Wilson Creek Range. The Blawn was preceded by voluminous Oligocene eruptions of dominantly calc-alkaline orogenic magmas. The Blawn and younger volcanic rocks in the area are low-volume, bimodal suites of high-silica rhyolite tuffs and lava flows and mafic lava flows.

Prognostic Value of Transthoracic Doppler Echocardiography Coronary Flow Velocity Reserve in Patients with Nonculprit Stenosis of Intermediate Severity Early after Primary Percutaneous Coronary Intervention.

PubMed

Tesic, Milorad; Djordjevic-Dikic, Ana; Giga, Vojislav; Stepanovic, Jelena; Dobric, Milan; Jovanovic, Ivana; Petrovic, Marija; Mehmedbegovic, Zlatko; Milasinovic, Dejan; Dedovic, Vladimir; Zivkovic, Milorad; Juricic, Stefan; Orlic, Dejan; Stojkovic, Sinisa; Vukcevic, Vladan; Stankovic, Goran; Nedeljkovic, Milan; Ostojic, Miodrag; Beleslin, Branko

2018-04-03

Treatment of nonculprit coronary stenosis during primary percutaneous coronary intervention in patients with ST-segment elevation myocardial infarction may be beneficial, but the mode and timing of the intervention are still controversial. The aim of this study was to examine the significance and prognostic value of preserved coronary flow velocity reserve (CFVR) in patients with nonculprit intermediate stenosis early after primary percutaneous coronary intervention. Two hundred thirty patients with remaining intermediate (50%-70%) stenosis of non-infarct-related arteries, in whom CFVR was performed within 7 days after primary percutaneous coronary intervention, were prospectively enrolled. Twenty patients with reduced CFVR and positive results on stress echocardiography or impaired fractional flow reserve underwent revascularization and were not included in further analysis. The final study population of 210 patients (mean age, 58 ± 10 years; 162 men) was divided into two groups on the basis of CFVR: group 1, CFVR > 2 (n = 174), and group 2, CFVR ≤ 2 (n = 36). Cardiac death, nonfatal myocardial infarction, and revascularization of the evaluated vessel were considered adverse events. Mean follow-up duration was 47 ± 16 months. Mean CFVR for the whole group was 2.36 ± 0.40. There were six adverse events (3.4%) related to the nonculprit coronary artery in group 1, including one cardiac death, one ST-segment elevation myocardial infarction, and four revascularizations. In group 2, there were 30 adverse events (83.3%, P < .001 vs group 1), including two cardiac deaths, two ST-segment elevation myocardial infarctions, and 26 revascularizations. In patients with CFVR > 2 of the intermediate nonculprit coronary lesion, deferral of revascularization is safe and associated with excellent long-term clinical outcomes. Copyright © 2018 American Society of Echocardiography. Published by Elsevier Inc. All rights reserved.

Internal Flow Analysis of Large L/D Solid Rocket Motors

NASA Technical Reports Server (NTRS)

Laubacher, Brian A.

2000-01-01

Traditionally, Solid Rocket Motor (SRM) internal ballistic performance has been analyzed and predicted with either zero-dimensional (volume filling) codes or one-dimensional ballistics codes. One dimensional simulation of SRM performance is only necessary for ignition modeling, or for motors that have large length to port diameter ratios which exhibit an axial "pressure drop" during the early burn times. This type of prediction works quite well for many types of motors, however, when motor aspect ratios get large, and port to throat ratios get closer to one, two dimensional effects can become significant. The initial propellant grain configuration for the Space Shuttle Reusable Solid Rocket Motor (RSRM) was analyzed with 2-D, steady, axi-symmetric computational fluid dynamics (CFD). The results of the CFD analysis show that the steady-state performance prediction at the initial burn geometry, in general, agrees well with 1-D transient prediction results at an early time, however, significant features of the 2-D flow are captured with the CFD results that would otherwise go unnoticed. Capturing these subtle differences gives a greater confidence to modeling accuracy, and additional insight with which to model secondary internal flow effects like erosive burning. Detailed analysis of the 2-D flowfield has led to the discovery of its hidden 1-D isentropic behavior, and provided the means for a thorough and simplified understanding of internal solid rocket motor flow. Performance parameters such as nozzle stagnation pressure, static pressure drop, characteristic velocity, thrust and specific impulse are discussed in detail and compared for different modeling and prediction methods. The predicted performance using both the 1-D codes and the CFD results are compared with measured data obtained from static tests of the RSRM. The differences and limitations of predictions using ID and 2-D flow fields are discussed and some suggestions for the design of large L/D motors and

Preliminary characterization of an expanding flow of siloxane vapor MDM

NASA Astrophysics Data System (ADS)

Spinelli, A.; Cozzi, F.; Cammi, G.; Zocca, M.; Gaetani, P.; Dossena, V.; Guardone, A.

2017-03-01

The early experimental results on the characterization of expanding flows of siloxane vapor MDM (C8H24O2Si3, octamethyltrisiloxane) are presented. The measurements were performed on the Test Rig for Organic VApors (TROVA) at the CREA Laboratory of Politecnico di Milano. The TROVA test-rig was built in order to investigate the non-ideal compressible-fluid behavior of typical expanding flows occurring within organic Rankine cycles (ORC) turbine passages. The test rig implements a batch Rankine cycle where a planar converging-diverging nozzle replaces the turbine and represents a test section. Investigations related to both fields of non-ideal compressible-fluid dynamics fundamentals and turbomachinery are allowed. The nozzle can be operated with different working fluids and operating conditions aiming at measuring independently the pressure, the temperature and the velocity field and thus providing data to verify the thermo-fluid dynamic models adopted to predict the behavior of these flows. The limiting values of pressure and temperature are 50 bar and 400 °C respectively. The early measurements are performed along the nozzle axis, where an isentropic process is expected to occur. In particular, the results reported here refer to the nozzle operated in adapted conditions using the siloxane vapor MDM as working fluid in thermodynamic regions where mild to medium non-ideal compressible-fluid effects are present. Both total temperature and total pressure of the nozzle are measured upstream of the test section, while static pressure are measured along the nozzle axis. Schlieren visualizations are also carried out in order to complement the pressure measurement with information about the 2D density gradient field. The Laser Doppler Velocimetry technique is planned to be used in the future for velocity measurements. The measured flow field has also been interpreted by resorting to the quasi-one-dimensional theory and two dimensional CFD viscous calculation. In both cases

Prediction of spatially explicit rainfall intensity–duration thresholds for post-fire debris-flow generation in the western United States

USGS Publications Warehouse

Staley, Dennis M.; Negri, Jacquelyn; Kean, Jason W.; Laber, Jayme L.; Tillery, Anne C.; Youberg, Ann M.

2017-01-01

Early warning of post-fire debris-flow occurrence during intense rainfall has traditionally relied upon a library of regionally specific empirical rainfall intensity–duration thresholds. Development of this library and the calculation of rainfall intensity-duration thresholds often require several years of monitoring local rainfall and hydrologic response to rainstorms, a time-consuming approach where results are often only applicable to the specific region where data were collected. Here, we present a new, fully predictive approach that utilizes rainfall, hydrologic response, and readily available geospatial data to predict rainfall intensity–duration thresholds for debris-flow generation in recently burned locations in the western United States. Unlike the traditional approach to defining regional thresholds from historical data, the proposed methodology permits the direct calculation of rainfall intensity–duration thresholds for areas where no such data exist. The thresholds calculated by this method are demonstrated to provide predictions that are of similar accuracy, and in some cases outperform, previously published regional intensity–duration thresholds. The method also provides improved predictions of debris-flow likelihood, which can be incorporated into existing approaches for post-fire debris-flow hazard assessment. Our results also provide guidance for the operational expansion of post-fire debris-flow early warning systems in areas where empirically defined regional rainfall intensity–duration thresholds do not currently exist.

Prediction of spatially explicit rainfall intensity-duration thresholds for post-fire debris-flow generation in the western United States

NASA Astrophysics Data System (ADS)

Staley, Dennis M.; Negri, Jacquelyn A.; Kean, Jason W.; Laber, Jayme L.; Tillery, Anne C.; Youberg, Ann M.

2017-02-01

Early warning of post-fire debris-flow occurrence during intense rainfall has traditionally relied upon a library of regionally specific empirical rainfall intensity-duration thresholds. Development of this library and the calculation of rainfall intensity-duration thresholds often require several years of monitoring local rainfall and hydrologic response to rainstorms, a time-consuming approach where results are often only applicable to the specific region where data were collected. Here, we present a new, fully predictive approach that utilizes rainfall, hydrologic response, and readily available geospatial data to predict rainfall intensity-duration thresholds for debris-flow generation in recently burned locations in the western United States. Unlike the traditional approach to defining regional thresholds from historical data, the proposed methodology permits the direct calculation of rainfall intensity-duration thresholds for areas where no such data exist. The thresholds calculated by this method are demonstrated to provide predictions that are of similar accuracy, and in some cases outperform, previously published regional intensity-duration thresholds. The method also provides improved predictions of debris-flow likelihood, which can be incorporated into existing approaches for post-fire debris-flow hazard assessment. Our results also provide guidance for the operational expansion of post-fire debris-flow early warning systems in areas where empirically defined regional rainfall intensity-duration thresholds do not currently exist.

The EOLE experiment: Early results and current objectives

NASA Technical Reports Server (NTRS)

Morel, P.; Bandeen, W. R.

1972-01-01

The EOLE experiment with 480 constant level balloons released in the Southern Hemisphere is described. Each balloon floating freely at approximately the 200 mb level, is a precise tracer of the horizontal motion of air masses, the accuracy of which is limited only by the laminated structure of the stratospheric flow, within an RMS uncertainty of 1.5 m/sec. The balloons were found after 2 months to distribute at random over the whole hemisphere outside the tropics, irrespective of their original launching site. Early results of Eulerian and Lagrangian averages of the EOLE wind data are given for describing the mean 200 mb zonal and meridional circulations. The effect of the small scale eddies of two-dimensional turbulence has been studied with respect to the relative eddy diffusion of pairs of balloons and the relative dispersion of triangular clusters. New estimates of the RMS divergence of the 200 mb flow are given, together with their scale dependence which was found to be a logarithmic law.

A new model for the emplacement of Columbia River basalts as large, inflated pahoehoe lava flow fields

USGS Publications Warehouse

Self, S.; Thordarson, Th.; Keszthelyi, L.; Walker, G.P.L.; Hon, K.; Murphy, M.T.; Long, P.; Finnemore, S.

1996-01-01

Extensive flows of the Columbia River Basalt (CRB) Group in Washington, Oregon, and Idaho are dominantly inflated compound pahoehoe sheet lavas. Early studies recognized that CRB lavas are compound pahoehoe flows, with textures suggesting low flow velocities, but it was thought that the great thickness and extent of the major flows required very rapid emplacement as turbulent floods of lava over a period of days or weeks. However, small volume ( < 1 km3) compound pahoehoe flows on Kilauea, Hawai'i, demonstrate that such flows can thicken by at least an order of magnitude through gradual inflation and the same mechanism has been proposed for larger (10-20 km3) pahoehoe flows in Iceland. The vertical distribution of vesicles and other morphologic features within CRB lava flows indicate that they grew similarly by inflation. Small pahoehoe lobes at the base and top of many CRB pahoehoe lava flows indicate emplacement in a gradual, piecemeal manner rather than as a single flood. We propose that each thick CRB sheet flow was active for months to years and that each group of flows produced by a single eruption (a flow field) was emplaced slowly over many years. Copyright 1996 by the American Geophysical Union.

GIS-based channel flow and sediment transport simulation using CCHE1D coupled with AnnAGNPS

USDA-ARS?s Scientific Manuscript database

CCHE1D (Center for Computational Hydroscience and Engineering 1-Dimensional model) simulates unsteady free-surface flows with nonequilibrium, nonuniform sediment transport in dendritic channel networks. Since early 1990’s, the model and its software packages have been developed and continuously main...

[Nailfold capillaroscopy and blood flow laser-doppler analysis of the microvascular damage in systemic sclerosis: preliminary results].

PubMed

Secchi, M E; Sulli, A; Pizzorni, C; Cutolo, M

2009-01-01

Systemic sclerosis (SSc) is characterized by altered microvascular structure and function. Nailfold videocapillaroscopy (NVC) is the tool to evaluate capillary morphological structure and laser-Doppler Blood flowmetry (LDF) can be used to estimate cutaneous blood flow of microvessels. The aim of this study was to investigate possible relationships between capillary morphology and blood flow in SSc. Twenty-seven SSc patients and 12 healthy subjects were enrolled. SSc microvascular involvement, as evaluated by NVC, was classified in three different patterns ("Early", "Active", "Late"). LDF analysis was performed at the II, III, IV, V hand fingers in both hands and both at cutaneous temperature and at 36 degrees C. Statistical evaluation was carried out by non-parametric procedures. Blood flow was found significantly lower in SSc patients when compared with healthy subjects (p<0.05). The heating of the probe to 36 degrees C induced a significant increase in peripheral blood flow in all subjects compared to baseline (p <0.05), however, the amount of variation was significantly lower in patients with SSc, compared with healthy controls (p <0.05). The SSc patients with NVC "Late" pattern, showed lower values of peripheral blood flow than patients with NVC "Active" or "Early" patterns (p<0.05). Moreover, a negative correlation between the tissue perfusion score and the progression of the SSc microangiopathy was observed, as well as between the tissue perfusion and the duration of the Raynaud's phenomenon (p <0.03). LDF can be employed to evaluate blood perfusion in the microvascular circulation in SSc patients. The blood flow changes observed with the LDF seem to correlate with the severity of microvascular damage in SSc as detected by NVC.

Resource Prospector Propulsion System Cold Flow Testing

NASA Technical Reports Server (NTRS)

Williams, Hunter; Holt, Kim; Addona, Brad; Trinh, Huu

2015-01-01

Resource Prospector (RP) is a NASA mission being led by NASA Ames Research Center with current plans to deliver a scientific payload package aboard a rover to the lunar surface. As part of an early risk reduction activity, Marshall Space Flight Center (MSFC) and Johnson Space Flight Center (JSC) have jointly developed a government-version concept of a lunar lander for the mission. The spacecraft consists of two parts, the lander and the rover which carries the scientific instruments. The lander holds the rover during launch, cruise, and landing on the surface. Following terminal descent and landing the lander portion of the spacecraft become dormant after the rover embarks on the science mission. The lander will be equipped with a propulsion system for lunar descent and landing, as well as trajectory correction and attitude control maneuvers during transit to the moon. Hypergolic propellants monomethyl hydrazine and nitrogen tetroxide will be used to fuel sixteen 70-lbf descent thrusters and twelve 5-lbf attitude control thrusters. A total of four metal-diaphragm tanks, two per propellant, will be used along with a high-pressure composite-overwrapped pressure vessel for the helium pressurant gas. Many of the major propulsion system components are heritage missile hardware obtained by NASA from the Air Force. In parallel with the flight system design activities, a simulated propulsion system based on flight drawings was built for conducting a series of water flow tests to characterize the transient fluid flow of the propulsion system feed lines and to verify the critical operation modes such as system priming, waterhammer, and crucial mission duty cycles. The primary objective of the cold flow testing was to simulate the RP propulsion system fluid flow operation through water flow testing and to obtain data for anchoring analytical models. The models will be used to predict the transient and steady state flow behaviors in the actual flight operations. All design and

Dynamic spatio-temporal imaging of early reflow in a neonatal rat stroke model.

PubMed

Leger, Pierre-Louis; Bonnin, Philippe; Lacombe, Pierre; Couture-Lepetit, Elisabeth; Fau, Sebastien; Renolleau, Sylvain; Gharib, Abdallah; Baud, Olivier; Charriaut-Marlangue, Christiane

2013-01-01

The aim of the study was to better understand blood-flow changes in large arteries and microvessels during the first 15 minutes of reflow in a P7 rat model of arterial occlusion. Blood-flow changes were monitored by using ultrasound imaging with sequential Doppler recordings in internal carotid arteries (ICAs) and basilar trunk. Relative cerebral blood flow (rCBF) changes were obtained by using laser speckle Doppler monitoring. Tissue perfusion was measured with [(14)C]-iodoantipyrine autoradiography. Cerebral energy metabolism was evaluated by mitochondrial oxygen consumption. Gradual increase in mean blood-flow velocities illustrated a gradual perfusion during early reflow in both ICAs. On ischemia, the middle cerebral artery (MCA) territory presented a residual perfusion, whereas the caudal territory remained normally perfused. On reflow, speckle images showed a caudorostral propagation of reperfusion through anastomotic connections, and a reduced perfusion in the MCA territory. Autoradiography highlighted the caudorostral gradient, and persistent perfusion in ventral and medial regions. These blood-flow changes were accompanied by mitochondrial respiration impairment in the ipsilateral cortex. Collectively, these data indicate the presence of a primary collateral pathway through the circle of Willis, providing an immediate diversion of blood flow toward ischemic regions, and secondary efficient cortical anastomoses in the immature rat brain.

Sub-Grid Modeling of Electrokinetic Effects in Micro Flows

NASA Technical Reports Server (NTRS)

Chen, C. P.

2005-01-01

Advances in micro-fabrication processes have generated tremendous interests in miniaturizing chemical and biomedical analyses into integrated microsystems (Lab-on-Chip devices). To successfully design and operate the micro fluidics system, it is essential to understand the fundamental fluid flow phenomena when channel sizes are shrink to micron or even nano dimensions. One important phenomenon is the electro kinetic effect in micro/nano channels due to the existence of the electrical double layer (EDL) near a solid-liquid interface. Not only EDL is responsible for electro-osmosis pumping when an electric field parallel to the surface is imposed, EDL also causes extra flow resistance (the electro-viscous effect) and flow anomaly (such as early transition from laminar to turbulent flow) observed in pressure-driven microchannel flows. Modeling and simulation of electro-kinetic effects on micro flows poses significant numerical challenge due to the fact that the sizes of the double layer (10 nm up to microns) are very thin compared to channel width (can be up to 100 s of m). Since the typical thickness of the double layer is extremely small compared to the channel width, it would be computationally very costly to capture the velocity profile inside the double layer by placing sufficient number of grid cells in the layer to resolve the velocity changes, especially in complex, 3-d geometries. Existing approaches using "slip" wall velocity and augmented double layer are difficult to use when the flow geometry is complicated, e.g. flow in a T-junction, X-junction, etc. In order to overcome the difficulties arising from those two approaches, we have developed a sub-grid integration method to properly account for the physics of the double layer. The integration approach can be used on simple or complicated flow geometries. Resolution of the double layer is not needed in this approach, and the effects of the double layer can be accounted for at the same time. With this

Physical conditions on the early Earth

PubMed Central

Lunine, Jonathan I

2006-01-01

The formation of the Earth as a planet was a large stochastic process in which the rapid assembly of asteroidal-to-Mars-sized bodies was followed by a more extended period of growth through collisions of these objects, facilitated by the gravitational perturbations associated with Jupiter. The Earth's inventory of water and organic molecules may have come from diverse sources, not more than 10% roughly from comets, the rest from asteroidal precursors to chondritic bodies and possibly objects near Earth's orbit for which no representative class of meteorites exists today in laboratory collections. The final assembly of the Earth included a catastrophic impact with a Mars-sized body, ejecting mantle and crustal material to form the Moon, and also devolatilizing part of the Earth. A magma ocean and steam atmosphere (possibly with silica vapour) existed briefly in this period, but terrestrial surface waters were below the critical point within 100 million years after Earth's formation, and liquid water existed continuously on the surface within a few hundred million years. Organic material delivered by comets and asteroids would have survived, in part, this violent early period, but frequent impacts of remaining debris probably prevented the continuous habitability of the Earth for one to several hundred million years. Planetary analogues to or records of this early time when life began include Io (heat flow), Titan (organic chemistry) and Venus (remnant early granites). PMID:17008213

Flow origin, drainage area, and hydrologic characteristics for headwater streams in the mountaintop coal-mining region of Southern West Virginia, 2000-01

USGS Publications Warehouse

Paybins, Katherine S.

2003-01-01

Characteristics of perennial and intermittent headwater streams were documented in the mountaintop removal coal-mining region of southern West Virginia in 2000?01. The perennial-flow origin points were identified in autumn during low base-flow conditions. The intermittent-flow origin points were identified in late winter and early spring during high base-flow conditions. Results of this investigation indicate that the median drainage area upstream of the origin of intermittent flow was 14.5 acres, and varied by an absolute median of 3.4 acres between the late winter measurements of 2000 and early spring measurements of 2001. Median drainage area in the northeastern part of the study unit was generally larger (20.4 acres), with a lower median basin slope (322 feet per mile) than the southwestern part of the study unit (12.9 acres and 465 feet per mile, respectively). Both of the seasons preceding the annual intermittent flow visits were much drier than normal. The West Virginia Department of Environmental Protection reports that the median size of permitted valley fills in southern West Virginia is 12.0 acres, which is comparable to the median drainage area upstream of the ephemeralintermittent flow point (14.5 acres). The maximum size of permitted fills (480 acres), however, is more than 10 times the observed maximum drainage area upstream of the ephemeral-intermittent flow point (45.3 acres), although a single valley fill may cover more than one drainage area. The median drainage area upstream of the origin of perennial flow was 40.8 acres, and varied by an absolute median of 18.0 acres between two annual autumn measurements. Only basins underlain with mostly sandstone bedrock produced perennial flow. Perennial points in the northeast part of the study unit had a larger median drainage area (70.0 acres) and a smaller median basin slope (416 feet per mile) than perennial points in the southwest part of the study unit (35.5 acres and 567 feet per mile, respectively

Early Right Ventricular Assist Device Use in Patients Undergoing Continuous-Flow Left Ventricular Assist Device Implantation: Incidence and Risk Factors From the Interagency Registry for Mechanically Assisted Circulatory Support.

PubMed

Kiernan, Michael S; Grandin, E Wilson; Brinkley, Marshall; Kapur, Navin K; Pham, Duc Thinh; Ruthazer, Robin; Rame, J Eduardo; Atluri, Pavan; Birati, Edo Y; Oliveira, Guilherme H; Pagani, Francis D; Kirklin, James K; Naftel, David; Kormos, Robert L; Teuteberg, Jeffrey J; DeNofrio, David

2017-10-01

To investigate preimplant risk factors associated with early right ventricular assist device (RVAD) use in patients undergoing continuous-flow left ventricular assist device (LVAD) surgery. Patients in the Interagency Registry for Mechanically Assisted Circulatory Support who underwent primary continuous-flow-LVAD surgery were examined for concurrent or subsequent RVAD implantation within 14 days of LVAD. Risk factors for RVAD implantation and the combined end point of RVAD or death within 14 days of LVAD were assessed with stepwise logistic regression. We compared survival between patients with and without RVAD using Kaplan-Meier method and Cox proportional hazards modeling. Of 9976 patients undergoing continuous-flow-LVAD implantation, 386 patients (3.9%) required an RVAD within 14 days of LVAD surgery. Preimplant characteristics associated with RVAD use included interagency registry for mechanically assisted circulatory support patient profiles 1 and 2, the need for preoperative extracorporeal membrane oxygenation or renal replacement therapy, severe preimplant tricuspid regurgitation, history of cardiac surgery, and concomitant procedures other than tricuspid valve repair at the time of LVAD. Hemodynamic determinants included elevated right atrial pressure, reduced pulmonary artery pulse pressure, and reduced stroke volume. The final model demonstrated good performance for both RVAD implant (area under the curve, 0.78) and the combined end point of RVAD or death within 14 days (area under the curve, 0.73). Compared with patients receiving an isolated LVAD, patients requiring RVAD had decreased 1- and 6-month survival: 78.1% versus 95.8% and 63.6% versus 87.9%, respectively ( P <0.0001 for both). The need for RVAD implantation after LVAD is associated with indices of global illness severity, markers of end-organ dysfunction, and profiles of hemodynamic instability. © 2017 American Heart Association, Inc.

Visualization study of flow in axial flow inducer.

NASA Technical Reports Server (NTRS)

Lakshminarayana, B.

1972-01-01

A visualization study of the flow through a three ft dia model of a four bladed inducer, which is operated in air at a flow coefficient of 0.065, is reported in this paper. The flow near the blade surfaces, inside the rotating passages, downstream and upstream of the inducer is visualized by means of smoke, tufts, ammonia filament, and lampblack techniques. Flow is found to be highly three dimensional, with appreciable radial velocity throughout the entire passage. The secondary flows observed near the hub and annulus walls agree with qualitative predictions obtained from the inviscid secondary flow theory.

Blood flow estimation in gastroscopic true-color images

NASA Astrophysics Data System (ADS)

Jacoby, Raffael S.; Herpers, Rainer; Zwiebel, Franz M.; Englmeier, Karl-Hans

1995-05-01

The assessment of blood flow in the gastrointestinal mucosa might be an important factor for the diagnosis and treatment of several diseases such as ulcers, gastritis, colitis, or early cancer. The quantity of blood flow is roughly estimated by computing the spatial hemoglobin distribution in the mucosa. The presented method enables a practical realization by calculating approximately the hemoglobin concentration based on a spectrophotometric analysis of endoscopic true-color images, which are recorded during routine examinations. A system model based on the reflectance spectroscopic law of Kubelka-Munk is derived which enables an estimation of the hemoglobin concentration by means of the color values of the images. Additionally, a transformation of the color values is developed in order to improve the luminance independence. Applying this transformation and estimating the hemoglobin concentration for each pixel of interest, the hemoglobin distribution can be computed. The obtained results are mostly independent of luminance. An initial validation of the presented method is performed by a quantitative estimation of the reproducibility.

Vortex shedding flow meter performance at high flow velocities

NASA Technical Reports Server (NTRS)

Siegwarth, J. D.

1986-01-01

In some of the ducts of the Space Shuttle Main Engine (SSME), the maximum liquid oxygen flow velocities approach 10 times those at which liquid flow measurements are normally made. The hydrogen gas flow velocities in other ducts exceed the maximum for gas flow measurement by more than a factor of 3. The results presented here show from water flow tests that vortex shedding flow meters of the appropriate design can measure water flow to velocities in excess of 55 m/s, which is a Reynolds number of about 2 million. Air flow tests have shown that the same meter can measure flow to a Reynolds number of at least 22 million. Vortex shedding meters were installed in two of the SSME ducts and tested with water flow. Narrow spectrum lines were obtained and the meter output frequencies were proportional to flow to + or - 0.5% or better over the test range with no flow conditioning, even though the ducts had multiple bends preceeding the meter location. Meters with the shedding elements only partially spanning the pipe and some meters with ring shaped shedding elements were also tested.

Flow diverter value and flow diversion method

NASA Technical Reports Server (NTRS)

Arline, S. B.; Carlson, R. L. (Inventor)

1964-01-01

A flow diverter valve applicable to any fluid flow system requiring rapid bleed or bypass is disclosed. Examples of application of the flow diverter valve to a liquid rocket and a turbojet aircraft engine are given. Features of the valve include: (1) an independent fluid source is used to activate the flow diverter valve toward its closed position during its initial stage of travel; (2) the flow diverter port area and size is unlimited and the valve travel is unlimited; and (3) the valve housing is fabricated such that the valve can be a one step valve, a two step valve, or include as many steps as are found desirable.

Physical training improves flow-mediated dilation in patients with the polymetabolic syndrome.

PubMed

Lavrencic, A; Salobir, B G; Keber, I

2000-02-01

Endothelial dysfunction that can be detected as impaired flow-mediated dilation by ultrasonography is an early event in atherogenesis and has been demonstrated in healthy subjects with risk factors for atherosclerosis many years before the appearance of atheromatous plaques. We examined the influence of physical training on flow-mediated dilation in patients with the polymetabolic syndrome. Twenty-nine asymptomatic men aged 40 to 60 years with the polymetabolic syndrome were randomly divided between the control group and the training group, which trained 3 times a week for 12 weeks. On high-resolution ultrasound images, the diameter of the brachial artery was measured at rest, after reactive hyperemia (causing flow-mediated, endothelium-dependent dilation), and after sublingual glyceryltrinitrate (causing endothelium-independent vasodilation) in all subjects before and after the training period. The training program induced an increase of 18% in physical fitness. Flow-mediated dilation increased from 5.3+/-2.8% to 7.3+/-2.7% (P<0. 05). There was no change in body mass index, blood pressure, insulin resistance, lipids, and big endothelin-1 in either group. Flow-mediated dilation measured before training was negatively correlated with resting heart rate, waist-to-hip ratio, and insulin resistance. Resting heart rate emerged as the only independent determinant, which explained 22% of the variation in flow-mediated dilation. In conclusion, our findings suggest that a 3-month physical training program, which improved maximal exercise capacity, enhances flow-mediated dilation in patients with the polymetabolic syndrome.

Spatiotemporal Responses of Groundwater Flow and Aquifer-River Exchanges to Flood Events

NASA Astrophysics Data System (ADS)

Liang, Xiuyu; Zhan, Hongbin; Schilling, Keith

2018-03-01

Rapidly rising river stages induced by flood events lead to considerable river water infiltration into aquifers and carry surface-borne solutes into hyporheic zones which are widely recognized as an important place for the biogeochemical activity. Existing studies for surface-groundwater exchanges induced by flood events usually limit to a river-aquifer cross section that is perpendicular to river channels, and neglect groundwater flow in parallel with river channels. In this study, surface-groundwater exchanges to a flood event are investigated with specific considerations of unconfined flow in direction that is in parallel with river channels. The groundwater flow is described by a two-dimensional Boussinesq equation and the flood event is described by a diffusive-type flood wave. Analytical solutions are derived and tested using the numerical solution. The results indicate that river water infiltrates into aquifers quickly during flood events, and mostly returns to the river within a short period of time after the flood event. However, the rest river water will stay in aquifers for a long period of time. The residual river water not only flows back to rivers but also flows to downstream aquifers. The one-dimensional model of neglecting flow in the direction parallel with river channels will overestimate heads and discharge in upstream aquifers. The return flow induced by the flood event has a power law form with time and has a significant impact on the base flow recession at early times. The solution can match the observed hydraulic heads in riparian zone wells of Iowa during flood events.

Flow Durations, Low-Flow Frequencies, and Monthly Median Flows for Selected Streams in Connecticut through 2005

USGS Publications Warehouse

Ahearn, Elizabeth A.

2008-01-01

Flow durations, low-flow frequencies, and monthly median streamflows were computed for 91 continuous-record, streamflow-gaging stations in Connecticut with 10 or more years of record. Flow durations include the 99-, 98-, 97-, 95-, 90-, 85-, 80-, 75-, 70-, 60-, 50-, 40-, 30-, 25-, 20-, 10-, 5-, and 1-percent exceedances. Low-flow frequencies include the 7-day, 10-year (7Q10) low flow; 7-day, 2-year (7Q2) low flow; and 30-day, 2-year (30Q2) low flow. Streamflow estimates were computed for each station using data for the period of record through water year 2005. Estimates of low-flow statistics for 7 short-term (operated between 3 and 10 years) streamflow-gaging stations and 31 partial-record sites were computed. Low-flow estimates were made on the basis of the relation between base flows at a short-term station or partial-record site and concurrent daily mean streamflows at a nearby index station. The relation is defined by the Maintenance of Variance Extension, type 3 (MOVE.3) method. Several short-term stations and partial-record sites had poorly defined relations with nearby index stations; therefore, no low-flow statistics were derived for these sites. The estimated low-flow statistics for the short-term stations and partial-record sites include the 99-, 98-, 97-, 95-, 90-, and 85-percent flow durations; the 7-day, 10-year (7Q10) low flow; 7-day, 2-year (7Q2) low flow; and 30-day, 2-year (30Q2) low-flow frequencies; and the August median flow. Descriptive information on location and record length, measured basin characteristics, index stations correlated to the short-term station and partial-record sites, and estimated flow statistics are provided in this report for each station. Streamflow estimates from this study are stored on USGS's World Wide Web application 'StreamStats' (http://water.usgs.gov/osw/streamstats/connecticut.html).

Eddy Current Minimizing Flow Plug for Use in Flow Conditioning and Flow Metering

NASA Technical Reports Server (NTRS)

England, John Dwight (Inventor); Kelley, Anthony R. (Inventor)

2015-01-01

An eddy-current-minimizing flow plug has open flow channels formed between the plug's inlet and outlet. Each open flow channel includes (i) a first portion that originates at the inlet face and converges to a location within the plug that is downstream of the inlet, and (ii) a second portion that originates within the plug and diverges to the outlet. The diverging second portion is approximately twice the length of the converging first portion. The plug is devoid of planar surface regions at its inlet and outlet, and in fluid flow planes of the plug that are perpendicular to the given direction of a fluid flowing therethrough.

The role of spray-enhanced swirl flow for combustion stabilization in a stratified-charge DISI engine

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

Zeng, Wei; Sjöberg, Magnus; Reuss, David L.

Implementing spray-guided stratified-charge direct-injection spark-ignited (DISI) engines is inhibited by the occurrence of misfire and partial burns. Engine-performance tests demonstrate that increasing engine speed induces combustion instability, but this deterioration can be prevented by generating swirling flow during the intake stroke. In-cylinder pressure-based heat-release analysis reveals that the appearance of poor-burn cycles is not solely dependent on the variability of early flame-kernel growth. Moreover, cycles can experience burning-rate regression during later combustion stages and may or may not recover before the end of the cycle. Thermodynamic analysis and optical diagnostics are used here to clarify why swirl improves the combustionmore » repeatability from cycle to cycle. The fluid dynamics of swirl/spray interaction was previously demonstrated using high-speed PIV measurements of in-cylinder motored flow. It was found that the sprays of the multi-hole injector redistribute the intake-generated swirl flow momentum, thereby creating a better-centered higher angular-momentum vortex with reduced variability. The engine operation with high swirl was found to have significant improvement in cycle-to-cycle variations of both flow pattern and flow momentum. This paper is an extension of the previous work. Here, PIV measurements and flame imaging are applied to fired operation for studying how the swirl flow affects variability of ignition and subsequent combustion phases. PIV results for fired operation are consistent with the measurements made of motored flow. They demonstrate that the spark-plasma motion is highly correlated with the direction of the gas flow in the vicinity of the spark-plug gap. Without swirl, the plasma is randomly stretched towards either side of the spark plug, causing variability in the ignition of the two spray plumes that are straddling the spark plug. Conversely, swirl flow always convects the spark plasma towards one

The role of spray-enhanced swirl flow for combustion stabilization in a stratified-charge DISI engine

DOE PAGES

Zeng, Wei; Sjöberg, Magnus; Reuss, David L.; ...

2016-06-01

Implementing spray-guided stratified-charge direct-injection spark-ignited (DISI) engines is inhibited by the occurrence of misfire and partial burns. Engine-performance tests demonstrate that increasing engine speed induces combustion instability, but this deterioration can be prevented by generating swirling flow during the intake stroke. In-cylinder pressure-based heat-release analysis reveals that the appearance of poor-burn cycles is not solely dependent on the variability of early flame-kernel growth. Moreover, cycles can experience burning-rate regression during later combustion stages and may or may not recover before the end of the cycle. Thermodynamic analysis and optical diagnostics are used here to clarify why swirl improves the combustionmore » repeatability from cycle to cycle. The fluid dynamics of swirl/spray interaction was previously demonstrated using high-speed PIV measurements of in-cylinder motored flow. It was found that the sprays of the multi-hole injector redistribute the intake-generated swirl flow momentum, thereby creating a better-centered higher angular-momentum vortex with reduced variability. The engine operation with high swirl was found to have significant improvement in cycle-to-cycle variations of both flow pattern and flow momentum. This paper is an extension of the previous work. Here, PIV measurements and flame imaging are applied to fired operation for studying how the swirl flow affects variability of ignition and subsequent combustion phases. PIV results for fired operation are consistent with the measurements made of motored flow. They demonstrate that the spark-plasma motion is highly correlated with the direction of the gas flow in the vicinity of the spark-plug gap. Without swirl, the plasma is randomly stretched towards either side of the spark plug, causing variability in the ignition of the two spray plumes that are straddling the spark plug. Conversely, swirl flow always convects the spark plasma towards one

A PURE HYDRODYNAMIC INSTABILITY IN SHEAR FLOWS AND ITS APPLICATION TO ASTROPHYSICAL ACCRETION DISKS

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

Nath, Sujit Kumar; Mukhopadhyay, Banibrata, E-mail: sujitkumar@physics.iisc.ernet.in, E-mail: bm@physics.iisc.ernet.in

2016-10-20

We provide a possible resolution for the century-old problem of hydrodynamic shear flows, which are apparently stable in linear analysis but shown to be turbulent in astrophysically observed data and experiments. This mismatch is noticed in a variety of systems, from laboratory to astrophysical flows. There are so many uncountable attempts made so far to resolve this mismatch, beginning with the early work of Kelvin, Rayleigh, and Reynolds toward the end of the nineteenth century. Here we show that the presence of stochastic noise, whose inevitable presence should not be neglected in the stability analysis of shear flows, leads tomore » pure hydrodynamic linear instability therein. This explains the origin of turbulence, which has been observed/interpreted in astrophysical accretion disks, laboratory experiments, and direct numerical simulations. This is, to the best of our knowledge, the first solution to the long-standing problem of hydrodynamic instability of Rayleigh-stable flows.« less

The Efficacy of International Regulation of Transborder Data Flows: The Case for the Clipper Chip.

ERIC Educational Resources Information Center

Mhlaba, Sondlo Leonard

1995-01-01

Discusses origins of Transborder Data Flows (TDFs) as an international problem in the early 1970s. Shows how technological development in telecommunications and networks has made regulation more complex and urgent. Recommends the internationalization of the Key Escrowed Encryption System (KEES) and the development of broad international TDF…

IgG1-iS18 impedes the adhesive and invasive potential of early and late stage malignant melanoma cells.

PubMed

Munien, Carmelle; Rebelo, Thalia M; Ferreira, Eloise; Weiss, Stefan F T

2017-02-15

The 37kDa/67kDa laminin receptor (LRP/LR) is a non-integrin laminin receptor which is overexpressed in tumorigenic cells and supports progression of cancer via promoting metastasis, angiogenesis and telomerase activity and impediment of apoptosis. The present study investigates the role of LRP/LR on the metastatic potential of early (A375) and late (A375SM) stage malignant melanoma cells. Flow cytometry revealed that both early and late stage malignant melanoma cells display high levels of LRP/LR on their cell surface. Flow cytometry and western blot analysis showed that late stage malignant melanoma cells display significantly higher total and cell surface LRP/LR levels in comparison to early stage malignant melanoma cells and the poorly invasive breast cancer (MCF-7) control cell line. Targeting LRP/LR using the LRP/LR specific antibody IgG1-iS18 resulted in a significant reduction of the adhesive potential to laminin-1 and the invasive potential through the 'ECM-simulating' Matrigel™ of both early and late stage malignant melanoma cells. Furthermore, Pearson's correlation coefficient confirmed that increased LRP levels correlate with the increased invasive and adhesive potential in early and late stage melanoma cells. Thus, blocking LRP/LR using the IgG1-iS18 antibody may therefore be a promising therapeutic strategy for early and late stage malignant melanoma treatment. Copyright © 2017 Elsevier Inc. All rights reserved.

Granular shear flows of flexible rod-like particles

NASA Astrophysics Data System (ADS)

Guo, Y.; Curtis, J.; Wassgren, C.; Ketterhagen, W.; Hancock, B.

2013-06-01

Flexible particles are widely encountered in nature, e.g., stalks of plants, fiberglass particles, and ceramic nanofibers. Early studies indicated that the deformability of particles has a significant impact on the properties of granular materials and fiber suspensions. In this study, shear flows of flexible particles are simulated using the Discrete Element Method (DEM) to explore the effect of particle flexibility on the flow behavior and constitutive laws. A flexible particle is formed by connecting a number of constituent spheres in a straight line using elastic bonds. The forces/moments due to the normal, tangential, bending, and torsional deformation of a bond resist the relative movement between two bonded constituent spheres. The bond stiffness determines how difficult it is to make a particle deform, and the bond damping accounts for the energy dissipation in the particle vibration process. The simulation results show that elastically bonded particles have smaller coefficients of restitution compared to rigidly connected particles, due to the fact that kinetic energy is partially converted to potential energy in a contact between flexible particles. The coefficient of restitution decreases as the bond stiffness decreases and the bond damping coefficient increases. As a result, smaller stresses are obtained for granular flows of the flexible particles with smaller bond stiffness and larger bond damping coefficient.

An unusual percutaneous transmitral commissurotomy: A collection of four rare occurrences!

PubMed

Shankarappa, Ravindranath K; Agrawal, Navin; Patra, Soumya; Karur, Satish; Nanjappa, Manjunath C

2013-09-01

We are presenting an interesting case of a 30-year-old patient taken for percutaneous transvenous mitral commissurotomy (PTMC) for severe rheumatic mitral stenosis in which there was a collection of four unusual occurrences during the course of a procedure. She had recurrent generalized tonic-clonic seizures immediately after femoral sheath insertion requiring the patient to be mechanically ventilated. Subsequently, the pressure tracings recorded with catheters in the aorta and the pulmonary artery showed transient unusually high supra-systemic pulmonary artery pressure. During inflation the Accura PTMC balloon which was used to dilate the mitral valve ruptured and the procedure subsequently had to be completed using another balloon catheter. During the procedure the presence of a distended stomach due to insufflations of air during positive pressure ventilation which subsided subsequently was another unusual documentation on fluoroscopy. The final outcome of the procedure was successful. This case presents an interesting collection of unusual occurrences during a PTMC procedure which started on an unusual note but ended on a successful one. Careful assessment and appropriate management of complications can lead to successful outcome of procedures as in our case.

Flow Cage Assemblies

NASA Technical Reports Server (NTRS)

Bar-Cohen, Yoseph (Inventor); Sherrit, Stewart (Inventor); Badescu, Mircea (Inventor); Bao, Xiaoqi (Inventor)

2017-01-01

Apparatus, systems and methods for implementing flow cages and flow cage assemblies in association with high pressure fluid flows and fluid valves are provided. Flow cages and flow assemblies are provided to dissipate the energy of a fluid flow, such as by reducing fluid flow pressure and/or fluid flow velocity. In some embodiments the dissipation of the fluid flow energy is adapted to reduce erosion, such as from high-pressure jet flows, to reduce cavitation, such as by controllably increasing the flow area, and/or to reduce valve noise associated with pressure surge.

Gas flow through rough microchannels in the transition flow regime.

PubMed

Deng, Zilong; Chen, Yongping; Shao, Chenxi

2016-01-01

A multiple-relaxation-time lattice Boltzmann model of Couette flow is developed to investigate the rarified gas flow through microchannels with roughness characterized by fractal geometry, especially to elucidate the coupled effects of roughness and rarefaction on microscale gas flow in the transition flow regime. The results indicate that the surface roughness effect on gas flow behavior becomes more significant in rarefied gas flow with the increase of Knudsen number. We find the gas flow behavior in the transition flow regime is more sensitive to roughness height than that in the slip flow regime. In particular, the influence of fractal dimension on rarefied gas flow behavior is less significant than roughness height.

Evaluation of Xerostomia and salivary flow rate in Hashimoto's Thyroiditis.

PubMed

Agha-Hosseini, Farzaneh; Shirzad, Nooshin; Moosavi, Mahdieh-Sadat

2016-01-01

One of the most common causes of hypothyroidism is Hashimoto's Thyroiditis (HT). Early detection of dry mouth is critical in preserving and promoting systemic and oral health. In this study we have assessed, for the first time, salivary function and xerostomia in HT patients who have not been involved with Sjögren's syndrome. HT was diagnosed in 40 patients based on clinical findings and positive anti-thyroid peroxidase antibodies (anti-TPO). Controls, matched by sex, age and body mass index (BMI), and with no history of thyroid disease, were selected. A questionnaire was used for diagnosis of xerostomia. Saliva samples were taken between 8 a.m. and 9 a.m., and at least 2 hours after the last intake of food or drink. The flow rate was calculated in milliliters per minute. Xerostomia was significantly higher in patients with HT. Unstimulated salivary flow rate was significantly lower in the HT group. Stimulated salivary flow rate was lower in HT group, but the difference was not significant. The patients with HT experienced xerostomia, and their salivary flow rate was diminished. Spitting the saliva then assessing salivary flow rate based on milliliter per minute is non-invasive, fast, and simple for chair-side diagnosis of dry mouth. Autoimmune diseases can be accompanied by salivary gland dysfunction. This may be due to the effect of cytokines in the autoimmune process or because of thyroid hormone dysfunctions.

Flow Instability and Flow Control Scaling Laws

NASA Astrophysics Data System (ADS)

van Ness, Daniel; Corke, Thomas; Morris, Scott

2006-11-01

A flow instability that is receptive to perturbations is present in the tip clearance leakage flow over the tip of a turbine blade. This instability was investigated through the introduction of active flow control in the viscous flow field. Control was implemented in the form of a dielectric barrier discharge created by a weakly-ionized plasma actuation arrangement. The experimental setup consisted of a low-speed linear turbine cascade made up of an array of nine Pratt & Whitney ``PakB'' turbine blades. This idealized cascade configuration was used to examine the tip clearance leakage flow that exists within the low pressure turbine stage of a gas-turbine engine. The center blade of the cascade array had a variable tip clearance up to five percent chord. Reynolds numbers based on axial blade chord varied from 10^4 to 10^5. Multi-port pressure probe measurements, as well as Stereo Particle Image Velocimetry were used to document the dependence of the instability on the frequency and amplitude of flow control perturbations. Scaling laws based on the variation of blade tip clearance height and inflow conditions were investigated. These results permitted an improved understanding of the mechanism of flow instability.

Comparison of hydrodynamic and semi-kinetic treatments for plasma flow along closed field lines

NASA Technical Reports Server (NTRS)

Singh, Nagendra; Wilson, G. R.; Horwitz, J. L.

1993-01-01

Hydrodynamic and semi-kinetic treatments of plasma flow along closed geomagnetic field lines are compared. The hydrodynamic treatment is based on a simplified 16-moment set of transport equations as the equations for the heat flows are not solved; the heat flows are treated heuristically. The semi-kinetic treatment is based on a particle code. The comparison deals with the distributions of the plasma density, flow velocity, and parallel and perpendicular temperatures as obtained from the two treatments during the various stages of the flow. In the kinetic treatment, the appropriate boundary condition is the prescription of the velocity distribution functions for the particles entering the flux tubes at the ionospheric boundaries; those particles leaving the system are determined by the processes occurring in the flux tube. The prescribed distributions are half-Maxwellian with temperature T(sub 0) and density n(sub 0). In the hydrodynamic model, the prescribed boundary conditions are on density (n(sub 0)), flow velocity (V(sub 0)) and temperature (T(sub 0). It was found that results from the hydrodynamic treatment critically depend on V(sub 0); for early stages of the flow this treatment yields results in good agreement with those from the kinetic treatment, when V(sub 0) = square root of (kT(sub 0)/2 (pi)m), which is the average velocity of particles moving in a given direction for a Maxwellian distribution. During this early stage, the flows developing form the conjugate ionospheres show some distinct transitions. For the first hour or so, the flows are highly supersonic and penetrate deep into the opposite hemispheres, and both hydrodynamics and kinetic treatments yield almost similar features. It is found that during this period heatflow effects are negligibly small. When a flow penetrates deep into the opposite hemisphere, the kinetic treatment predicts reflection and setting up of counterstreaming. In contrast, the hydrodynamic treatment yields a shock in the

Intra-arterial brachytherapy of hepatic malignancies: watch the flow.

PubMed

Morgan, Bruno; Kennedy, Andrew S; Lewington, Val; Jones, Bleddyn; Sharma, Ricky A

2011-02-01

Although the liver possesses a dual blood supply, arterial vessels deliver only a small proportion of blood to normal parenchyma, but they deliver the vast majority of blood to primary and secondary cancers of the liver. This anatomical discrepancy is the basis for intra-arterial brachytherapy of liver cancers using radioactive microspheres, termed radio-embolization (RE). Radioactive microspheres implant preferentially in the terminal arterioles of tumors. Although biological models of the flow dynamics and distribution of microspheres are currently in development, there is a need to improve the imaging biomarkers of flow dynamics used to plan RE. Since a direct consequence of RE is vascular disruption and necrosis, we suggest that imaging protocols sensitive to changes in vasculature are highly likely to represent useful early biomarkers for treatment efficacy. We propose dynamic contrast-enhanced CT as the most appropriate imaging modality for studying vascular parameters in clinical trials of RE treatment.

Enzyme replacement therapy with agalsidase beta improves cardiac involvement in Fabry's disease.

PubMed

Spinelli, L; Pisani, A; Sabbatini, M; Petretta, M; Andreucci, M V; Procaccini, D; Lo Surdo, N; Federico, S; Cianciaruso, B

2004-08-01

Fabry's disease is an X-linked lysosomal storage disease caused by a deficiency of alpha-galactosidase that results in an accumulation of neutral glycosphingolipids throughout the body, including the cardiovascular system. Fabry cardiomyopathy, characterized by progressive severe concentric left ventricular (LV) hypertrophy, is very frequent and is the most important cause of death in affected patients. Enzyme replacement therapy (ERT) allows a specific treatment for this disease, however, there are very few data on the effectiveness of therapy on cardiac involvement. Nine patients with Fabry cardiac disease were studied on basal condition and after 6 and 12 months of treatment with algasidase beta (Fabrazyme). A complete clinical, electrocardiographic and echocardiographic evaluation was performed in all patients. Interpretable Doppler recordings of transmitral flow and pulmonary flow velocity curves were also acquired. At baseline, the patients with Fabry's disease had increased LV septum and posterior wall thickness, normal LV fractional shortening, LV ejection fraction, normal Doppler parameters of mitral inflow but a duration of pulmonary vein flow velocity wave exceeding that of the mitral wave at atrial systole. ERT did not affect heart rate and arterial pressure. LV internal diameters did not change, there was a slight but not significant decrease in the LV posterior wall thickening and a progressive decrease in the interventricular septum thickening (p < 0.025) and in LV mass (p < 0.001) The difference in duration between pulmonary vein flow velocity wave and mitral wave at atrial systole significantly decreased (p < 0.001). These results suggest that ERT in patients with Fabry cardiomyopathy is able to reduce the LV mass and ameliorate the LV stiffness. Copyright 2004 Blackwell Munksgaard

Role of reduced insulin-stimulated bone blood flow in the pathogenesis of metabolic insulin resistance and diabetic bone fragility.

PubMed

Hinton, Pamela S

2016-08-01

Worldwide, 387 million adults live with type 2 diabetes (T2D) and an additional 205 million cases are projected by 2035. Because T2D has numerous complications, there is significant morbidity and mortality associated with the disease. Identification of early events in the pathogenesis of insulin resistance and T2D might lead to more effective treatments that would mitigate health and monetary costs. Here, we present our hypothesis that impaired bone blood flow is an early event in the pathogenesis of whole-body metabolic insulin resistance that ultimately leads to T2D. Two recent developments in different fields form the basis for this hypothesis. First, reduced vascular function has been identified as an early event in the development of T2D. In particular, before the onset of tissue or whole body metabolic insulin resistance, insulin-stimulated, endothelium-mediated skeletal muscle blood flow is impaired. Insulin resistance of the vascular endothelium reduces delivery of insulin and glucose to skeletal muscle, which leads to tissue and whole-body metabolic insulin resistance. Second is the paradigm-shifting discovery that the skeleton has an endocrine function that is essential for maintenance of whole-body glucose homeostasis. Specifically, in response to insulin signaling, osteoblasts secret osteocalcin, which stimulates pancreatic insulin production and enhances insulin sensitivity in skeletal muscle, adipose, and liver. Furthermore, the skeleton is not metabolically inert, but contributes to whole-body glucose utilization, consuming 20% that of skeletal muscle and 50% that of white adipose tissue. Without insulin signaling or without osteocalcin activity, experimental animals become hyperglycemic and insulin resistant. Currently, it is not known if insulin-stimulated, endothelium-mediated blood flow to bone plays a role in the development of whole body metabolic insulin resistance. We hypothesize that it is a key, early event. Microvascular dysfunction is a

Table Mountain Shoshonite Porphyry Lava Flows and Their Vents, Golden, Colorado

USGS Publications Warehouse

Drewes, Harald

2008-01-01

During early Paleocene time shoshonite porphyry lava was extruded from several plugs about 5 km north of Golden, Colo., to form lava flows intercalated in the upper part of the Denver Formation. These flows now form the caps of North and South Table Mountains. Detailed field and petrographic studies provide insights into magma development, linkage between vents and flows, and the history of the lava flows. The magma was derived from a deep (mantle) source, was somewhat turbulent on its way up, paused on its way up in a shallow granite-hosted chamber, and near the surface followed the steep Golden fault and the thick, weak, steeply dipping Upper Cretaceous Pierre Shale. At the surface the lava flowed out of several plug and dike vents in a nonexplosive manner, four times during a span of about 1 m.y. Potassium-rich material acquired in the shallow chamber produced distinctive textures and mineral associations in the igneous rocks. Lava flows 1 (the lowest) and 2 are channel deposits derived from the southeastern group of intrusions, and flow 1 (a composite, multiple-tongued flow) lies about 50 m below the capping flows. Provisionally, the unit termed flow 1 is considered to include older, felty-textured flows that are distinguished from a blocky-textured unit, flow 1a. Flow 2, newly recognized in this study, lies immediately beneath the capping flows. Lava flows 3 and 4, more voluminous than the earlier ones, were derived from a plug vent 1?2 km farther north-northwest and flowed south-southeast across a broad alluvial plain. This plug is a composite body; the rim phase fed flow 3, and the core phase was the source of flow 4. During the time between the effusion of the four flows, the composition of the shoshonite porphyry magma changed subtly; the later flows contain more alkali, as shown by higher proportions of sanidine. On North Table Mountain, lava flows 3 and 4 form an elongate tumulus above a stream channel that carried water at the time of their eruption. On

Plant uprooting by flow as a fatigue mechanical process

NASA Astrophysics Data System (ADS)

Perona, Paolo; Edmaier, Katharina; Crouzy, Benoît

2015-04-01

In river corridors, plant uprooting by flow mostly occurs as a delayed process where flow erosion first causes root exposure until residual anchoring balances hydrodynamic forces on the part of the plant that is exposed to the stream. Because a given plant exposure time to the action of the stream is needed before uprooting occurs (time-to-uprooting), this uprooting mechanism has been denominated Type II, in contrast to Type I, which mostly affect early stage seedlings and is rather instantaneous. In this work, we propose a stochastic framework that describes a (deterministic) mechanical fatigue process perturbed by a (stochastic) process noise, where collapse occurs after a given exposure time. We test the model using the experimental data of Edmaier (2014) and Edmaier et al. (submitted), who investigated vegetation uprooting by flow in the limit of low plant stem-to-sediment size ratio by inducing parallel riverbed erosion within an experimental flume. We first identify the proper timescale and lengthscale for rescaling the model. Then, we show that it describes well all the empirical cumulative distribution functions (cdf) of time-to-uprooting obtained under constant riverbed erosion rate and assuming additive gaussian process noise. By this mean, we explore the level of determinism and stochasticity affecting the time-to-uprooting for Avena sativa in relation to root anchoring and flow drag forces. We eventually ascribe the overall dynamics of the Type II uprooting mechanism to the memory of the plant-soil system that is stored by root anchoring, and discuss related implications thereof. References Edmaier, K., Uprooting mechansims of juvenile vegetation by flow erosion, Ph.D. thesis, EPFL, 2014. Edmaier, K., Crouzy, B. and P. Perona. Experimental characterization of vegetation uprooting by flow. J. of Geophys. Res. - Biogeosci., submitted

Aortic Valve Stenosis Increases Helical Flow and Flow Complexity: A Study of Intra-Operative Cardiac Vector Flow Imaging.

PubMed

Hansen, Kristoffer Lindskov; Møller-Sørensen, Hasse; Kjaergaard, Jesper; Jensen, Maiken Brit; Jensen, Jørgen Arendt; Nielsen, Michael Bachmann

2017-08-01

Aortic valve stenosis alters blood flow in the ascending aorta. Using intra-operative vector flow imaging on the ascending aorta, secondary helical flow during peak systole and diastole, as well as flow complexity of primary flow during systole, were investigated in patients with normal, stenotic and replaced aortic valves. Peak systolic helical flow, diastolic helical flow and flow complexity during systole differed between the groups (p < 0.0001), and correlated to peak systolic velocity (R = 0.94, 0.87 and 0.88, respectively). The study indicates that aortic valve stenosis increases helical flow and flow complexity, which are measurable with vector flow imaging. For assessment of aortic stenosis and optimization of valve surgery, vector flow imaging may be useful. Copyright © 2017 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

Flow visualization in long neck Helmholtz resonators with grazing flow

NASA Technical Reports Server (NTRS)

Baumeister, K. J.; Rice, E. J.

1976-01-01

Both oscillating and steady flows were applied to a single plexiglass resonator cavity with colored dyes injected in both the orifice and grazing flow field to record the motion of the fluid. For oscillatory flow, the instantaneous dye streamlines were similar for both the short and long-neck orifices. The orifice flow blockage appears to be independent of orifice length for a fixed amplitude of flow oscillation and magnitude of the grazing flow. The steady flow dye studies showed that the acoustic and steady flow resistances do not necessarily correspond for long neck orifices.

A new method for calculating ecological flow: Distribution flow method

NASA Astrophysics Data System (ADS)

Tan, Guangming; Yi, Ran; Chang, Jianbo; Shu, Caiwen; Yin, Zhi; Han, Shasha; Feng, Zhiyong; Lyu, Yiwei

2018-04-01

A distribution flow method (DFM) and its ecological flow index and evaluation grade standard are proposed to study the ecological flow of rivers based on broadening kernel density estimation. The proposed DFM and its ecological flow index and evaluation grade standard are applied into the calculation of ecological flow in the middle reaches of the Yangtze River and compared with traditional calculation method of hydrological ecological flow, method of flow evaluation, and calculation result of fish ecological flow. Results show that the DFM considers the intra- and inter-annual variations in natural runoff, thereby reducing the influence of extreme flow and uneven flow distributions during the year. This method also satisfies the actual runoff demand of river ecosystems, demonstrates superiority over the traditional hydrological methods, and shows a high space-time applicability and application value.

Safety Early Warning Research for Highway Construction Based on Case-Based Reasoning and Variable Fuzzy Sets

PubMed Central

Liu, Yan; Xu, Zhen-Jun

2013-01-01

As a high-risk subindustry involved in construction projects, highway construction safety has experienced major developments in the past 20 years, mainly due to the lack of safe early warnings in Chinese construction projects. By combining the current state of early warning technology with the requirements of the State Administration of Work Safety and using case-based reasoning (CBR), this paper expounds on the concept and flow of highway construction safety early warnings based on CBR. The present study provides solutions to three key issues, index selection, accident cause association analysis, and warning degree forecasting implementation, through the use of association rule mining, support vector machine classifiers, and variable fuzzy qualitative and quantitative change criterion modes, which fully cover the needs of safe early warning systems. Using a detailed description of the principles and advantages of each method and by proving the methods' effectiveness and ability to act together in safe early warning applications, effective means and intelligent technology for a safe highway construction early warning system are established. PMID:24191134

Safety early warning research for highway construction based on case-based reasoning and variable fuzzy sets.

PubMed

Liu, Yan; Yi, Ting-Hua; Xu, Zhen-Jun

2013-01-01

As a high-risk subindustry involved in construction projects, highway construction safety has experienced major developments in the past 20 years, mainly due to the lack of safe early warnings in Chinese construction projects. By combining the current state of early warning technology with the requirements of the State Administration of Work Safety and using case-based reasoning (CBR), this paper expounds on the concept and flow of highway construction safety early warnings based on CBR. The present study provides solutions to three key issues, index selection, accident cause association analysis, and warning degree forecasting implementation, through the use of association rule mining, support vector machine classifiers, and variable fuzzy qualitative and quantitative change criterion modes, which fully cover the needs of safe early warning systems. Using a detailed description of the principles and advantages of each method and by proving the methods' effectiveness and ability to act together in safe early warning applications, effective means and intelligent technology for a safe highway construction early warning system are established.

Static Flow Characteristics of a Mass Flow Injecting Valve

NASA Technical Reports Server (NTRS)

Mattern, Duane; Paxson, Dan

1995-01-01

A sleeve valve is under development for ground-based forced response testing of air compression systems. This valve will be used to inject air and to impart momentum to the flow inside the first stage of a multi-stage compressor. The valve was designed to deliver a maximum mass flow of 0.22 lbm/s (0.1 kg/s) with a maximum valve throat area of 0.12 sq. in (80 sq. mm), a 100 psid (689 KPA) pressure difference across the valve and a 68 F, (20 C) air supply. It was assumed that the valve mass flow rate would be proportional to the valve orifice area. A static flow calibration revealed a nonlinear valve orifice area to mass flow relationship which limits the maximum flow rate that the valve can deliver. This nonlinearity was found to be caused by multiple choking points in the flow path. A simple model was used to explain this nonlinearity and the model was compared to the static flow calibration data. Only steady flow data is presented here. In this report, the static flow characteristics of a proportionally controlled sleeve valve are modelled and validated against experimental data.

Vehicular Traffic Flow Theory and Tunnel Traffic Flow Measurements

DOT National Transportation Integrated Search

1971-06-01

Vehicular traffic flow has been investigated theoretically and experimentally in order that peak hour collective traffic flow dynamics can be understood and that the peak hour flow through the Callahan Tunnel can be improved by means of traffic flow ...

A basal magma ocean dynamo to explain the early lunar magnetic field

NASA Astrophysics Data System (ADS)

Scheinberg, Aaron L.; Soderlund, Krista M.; Elkins-Tanton, Linda T.

2018-06-01

The source of the ancient lunar magnetic field is an unsolved problem in the Moon's evolution. Theoretical work invoking a core dynamo has been unable to explain the magnitude of the observed field, falling instead one to two orders of magnitude below it. Since surface magnetic field strength is highly sensitive to the depth and size of the dynamo region, we instead hypothesize that the early lunar dynamo was driven by convection in a basal magma ocean formed from the final stages of an early lunar magma ocean; this material is expected to be dense, radioactive, and metalliferous. Here we use numerical convection models to predict the longevity and heat flow of such a basal magma ocean and use scaling laws to estimate the resulting magnetic field strength. We show that, if sufficiently electrically conducting, a magma ocean could have produced an early dynamo with surface fields consistent with the paleomagnetic observations.

Mantle flow and deforming continents, the Tethys realm

NASA Astrophysics Data System (ADS)

Jolivet, L.; Faccenna, C.; Becker, T. W.

2016-12-01

Continent deformation is partly a consequence of plate motion along plate boundaries. Whether underlying asthenospheric flow can also deform continents through basal shear or push on topographic irregularities of the base of the lithosphere is an open question. Eurasia has been extending at different scales since 50 Ma, from the Mediterranean back-arc domains to extension of Asia between the India-Asia collision zone and the Pacific subduction zones. While compression at plate margins, in subduction or collision zones can propagate far within continents, the mechanism explaining extension distributed over thousands of kilometres is unclear. We use trajectories of continental plates and continental fragments since 50 Myrs in different kinematic frames and compare them with various proxies of asthenospheric flow such as seismic anisotropy at various depths. These trajectories partly fit sub-lithospheric seismic anisotropy with two main circulations, one carrying Africa and Eurasia away from the large low velocity anomaly (LLSVP) underlying South and West Africa and one carrying the Pacific plate away from the LLSVP underlying the southern Pacific. Under eastern Eurasia the flow converges with the Pacific flow and distributed extension affects eastern Asia all the way to Western Pacific back-arc basins. We speculate that the flow carrying India northward and Eurasia eastward has invaded the Pacific domain and caused this widely distributed extension that interferes with the strike-slip faults issued from the Himalaya-Tibet collision zone. This model is in line with earlier propositions based on geochemical proxies. We discuss this model and compare it to other widely distributed extensional deformation episodes such as the Early Cretaceous extension of Africa and finally propose a scheme of large-scale continental deformation in relation to underlying mantle convection at different scales.

Water-Rock Differentiation of Icy Bodies by Darcy law, Stokes law, and Two-Phase Flow

NASA Astrophysics Data System (ADS)

Neumann, Wladimir; Breuer, Doris; Spohn, Tilman

2016-10-01

The early Solar system produced a variety of bodies with different properties. Among the small bodies, objects that contain notable amounts of water ice are of particular interest. Water-rock separation on such worlds is probable and has been confirmed in some cases. We couple accretion and water-rock separation in a numerical model. The model is applicable to Ceres, icy satellites, and Kuiper belt objects, and is suited to assess the thermal metamorphism of the interior and the present-day internal structures. The relative amount of ice determines the differentiation regime according to porous flow or Stokes flow. Porous flow considers differentiation in a rock matrix with a small degree of ice melting and is typically modelled either with the Darcy law or two-phase flow. We find that for small icy bodies two-phase flow differs from the Darcy law. Velocities derived from two-phase flow are at least one order of magnitude smaller than Darcy velocities. The latter do not account for the matrix resistance against the deformation and overestimate the separation velocity. In the Stokes regime that should be used for large ice fractions, differentiation is at least four orders of magnitude faster than porous flow with the parameters used here.

Early versus delayed internal urethrotomy for recurrent urethral stricture after urethroplasty in children.

PubMed

Hosseini, Seyyed Yousef; Safarinejad, Mohammad Reza

2005-01-01

Our aim was to evaluate the results of early versus delayed internal urethrotomy for management of recurrent urethral strictures after posterior urethroplasty in children. Twenty boys with proven posterior urethral strictures were treated by perineal posterior urethroplasty. Of these, 12 required internal urethrotomy. Each radiograph demonstrated a patent but irregular urethra with a decrease in diameter at the point of repair (fair results). Patients were then divided into 2 groups: 6 underwent early (within 6 weeks from urethroplasty), and 6 underwent delayed (after 12 weeks from urethroplasty), internal urethrotomy with the cold knife as a complementary treatment. The groups were comparable in terms of patient age, etiology of the primary urethral stricture, number of recurrences, length and site of the actual stricture, and preoperative maximum flow rate. Mean follow-up was 5 years. Kaplan-Meier analyses showed that the stricture-free rate was 66.6% after early, and 33.3% after delayed, internal urethrotomy (P = .03). Early internal urethrotomy should be considered in boys with recurrent urethral stricture after urethroplasty.

Hydraulic-property estimates for use with a transient ground-water flow model of the Death Valley regional ground-water flow system, Nevada and California

USGS Publications Warehouse

Belcher, Wayne R.; Elliott, Peggy E.; Geldon, Arthur L.

2001-01-01

The Death Valley regional ground-water flow system encompasses an area of about 43,500 square kilometers in southeastern California and southern Nevada, between latitudes 35? and 38?15' north and longitudes 115? and 117?45' west. The study area is underlain by Quaternary to Tertiary basin-fill sediments and mafic-lava flows; Tertiary volcanic, volcaniclastic, and sedimentary rocks; Tertiary to Jurassic granitic rocks; Triassic to Middle Proterozoic carbonate and clastic sedimentary rocks; and Early Proterozoic igneous and metamorphic rocks. The rock assemblage in the Death Valley region is extensively faulted as a result of several episodes of tectonic activity. This study is comprised of published and unpublished estimates of transmissivity, hydraulic conductivity, storage coefficient, and anisotropy ratios for hydrogeologic units within the Death Valley region study area. Hydrogeologic units previously proposed for the Death Valley regional transient ground-water flow model were recognized for the purpose of studying the distribution of hydraulic properties. Analyses of regression and covariance were used to assess if a relation existed between hydraulic conductivity and depth for most hydrogeologic units. Those analyses showed a weak, quantitatively indeterminate, relation between hydraulic conductivity and depth.

Is flow cytometric evaluation of DNA degradation a reliable method to investigate the early postmortem period?

PubMed

Di Nunno, N R; Costantinides, F; Bernasconi, P; Bottin, C; Melato, M

1998-03-01

The time of death can be established by determining the length of the postmortem interval. Many methods have been proposed to achieve this goal. Flow cytometric evaluation of DNA degradation seems to be reliable for the first 72 hours after death. Our study evaluated the correspondence of the corruption process between in vitro and corpse tissues. We chose spleen tissue to perform our investigation because it is rich in nucleated cells. Results showed a precise correspondence between the two kinds of samples in the time period between 24 and 36 hours. The period from 36 to 72 hours is characterized by a much looser correspondence than that found in the first period. After the first 72 hours, DNA denaturation is massive and does not allow useful cytofluorimetric readings. The spleen does not seem to be the most suitable organ for this type of investigation because it tends to colliquate very rapidly. We therefore are evaluating other organs to identify a more suitable tissue source for the investigation of longer postmortem period using flow cytometry.

Flow in the left anterior descending coronary artery in patients with migraine headache.

PubMed

Aslan, Gamze; Sade, Leyla Elif; Yetis, Begum; Bozbas, Huseyin; Eroglu, Serpil; Pirat, Bahar; Can, Ufuk; Muderrisoglu, Haldun

2013-11-15

Migraine is a common neurovascular disorder characterized by attacks of severe headache, autonomic and neurologic symptoms. Migraine can affect many systems in the body, yet its effects on cardiovascular system are unclear. We hypothesized that migraine and coronary microvascular angina may be manifestations of a common systemic microvascular dysfunction and clinically associated. Forty patients with migraine and 35 healthy volunteers were included into the study. Using transthoracic Doppler echocardiography, coronary flow was visualized in the middle or distal part of the left anterior descending artery. Coronary diastolic peak flow velocities were measured with pulse wave Doppler at baseline and after dipyridamole infusion (0.56 mg/kg/4 min). Coronary flow reserve of <2 was considered normal. In addition, thorough 2-dimensional and Doppler echocardiographic examinations were also performed. Fifty-two women and 23 men were included. Coronary flow reserve was significantly lesser in the migraine group than in the control group (1.99 ± 0.3 vs 2.90 ± 0.5, p <0.05). In addition, mitral annular velocities were lower and the ratio of early mitral inflow velocity to early mitral annular velocity (E/E' lateral and E/E' septal) was higher in migraineurs than in the control group (p <0.05 for all), indicating diastolic function abnormalities in the migraine group. In conclusion, these findings suggest that there is an association between coronary microvascular dysfunction and migraine independently of the metabolic state of the patients. A common pathophysiologic pathway of impaired endothelial vasodilatation, vasomotor dysfunction, and increased systemic inflammatory factors may play a role in these 2 clinical conditions and could be the underlying cause of subclinical systolic and diastolic left ventricular dysfunction in migraineurs. Copyright © 2013 Elsevier Inc. All rights reserved.

Capture of circulating tumor cells using photoacoustic flowmetry and two phase flow

NASA Astrophysics Data System (ADS)

O'Brien, Christine M.; Rood, Kyle D.; Bhattacharyya, Kiran; DeSouza, Thiago; Sengupta, Shramik; Gupta, Sagar K.; Mosley, Jeffrey D.; Goldschmidt, Benjamin S.; Sharma, Nikhilesh; Viator, John A.

2012-06-01

Melanoma is the deadliest form of skin cancer, yet current diagnostic methods are unable to detect early onset of metastatic disease. Patients must wait until macroscopic secondary tumors form before malignancy can be diagnosed and treatment prescribed. Detection of cells that have broken off the original tumor and travel through the blood or lymph system can provide data for diagnosing and monitoring metastatic disease. By irradiating enriched blood samples spiked with cultured melanoma cells with nanosecond duration laser light, we induced photoacoustic responses in the pigmented cells. Thus, we can detect and enumerate melanoma cells in blood samples to demonstrate a paradigm for a photoacoustic flow cytometer. Furthermore, we capture the melanoma cells using microfluidic two phase flow, a technique that separates a continuous flow into alternating microslugs of air and blood cell suspension. Each slug of blood cells is tested for the presence of melanoma. Slugs that are positive for melanoma, indicated by photoacoustic waves, are separated from the cytometer for further purification and isolation of the melanoma cell. In this paper, we evaluate the two phase photoacoustic flow cytometer for its ability to detect and capture metastastic melanoma cells in blood.

Mechanical Design of a Performance Test Rig for the Turbine Air-Flow Task (TAFT)

NASA Technical Reports Server (NTRS)

Forbes, John C.; Xenofos, George D.; Farrow, John L.; Tyler, Tom; Williams, Robert; Sargent, Scott; Moharos, Jozsef

2004-01-01

To support development of the Boeing-Rocketdyne RS84 rocket engine, a full-flow, reaction turbine geometry was integrated into the NASA-MSFC turbine air-flow test facility. A mechanical design was generated which minimized the amount of new hardware while incorporating all test and instrumentation requirements. This paper provides details of the mechanical design for this Turbine Air-Flow Task (TAFT) test rig. The mechanical design process utilized for this task included the following basic stages: Conceptual Design. Preliminary Design. Detailed Design. Baseline of Design (including Configuration Control and Drawing Revision). Fabrication. Assembly. During the design process, many lessons were learned that should benefit future test rig design projects. Of primary importance are well-defined requirements early in the design process, a thorough detailed design package, and effective communication with both the customer and the fabrication contractors.

Intraoperative coronary grafts flow measurement using the TTFM flowmeter: results from a domestic sample.

PubMed

Succi, José Ernesto; Gerola, Luis Roberto; Succi, Guilherme de Menezes; Kim, Hyong Chun; Paredes, Jorge Edwin Morocho; Bufollo, Enio

2012-01-01

To evaluate intraoperative graft patency and identify grafts under risk of early occlusion. Fifty four patients were submitted to coronary artery bypass surgery and the graft flow was assessed by the Flowmeter (Medtronic Medistim), which utilizes the TTFM method. Three patients had left main disease and 48 had normal or mildly reduced left ventricular function. In hospital mortality was 3.7% (two patients), one for mesenteric thrombosis and one due to cardiogenic chock. Seventeen patients (34%) were submitted to off pump CABG. Arterial Graft flow measures ranged from 8 to 106 ml/min (average 31.14 ml/min), and venous grafts flow ranged from 9 to 149 ml/min (average 50.42 ml/min). Flowmeter use represents higher safety both for patients and surgeons. Even under legal aspects, the documentation provided by the device can avoid future questionings.

Early time evolution of a chemically produced electron depletion

NASA Technical Reports Server (NTRS)

Scales, W. A.; Bernhardt, P. A.; Ganguli, G.

1995-01-01

The early time evolution of an ionospheric electron depletion produced by a radially expanding electron attachment chemical release is studied with a two-dimensional simulation model. The model includes electron attachment chemistry, incorporates fluid electrons, particle ions and neutrals, and considers the evolution in a plane perpendicular to the geomagnetic field for a low beta plasma. Timescales considered are of the order of or less than the cyclotron period of the negative ions that result as a by-product of the electron attacment reaction. This corresponds to time periods of tenths of seconds during recent experiemts. Simulation results show that a highly sheared azimuthal electron flow velocity develops in the radially expanding depletion boundary. This sheared electron flow velocity and the steep density gradients in the boundary give rise to small-scale irregulatities in the form of electron density cavities and spikes. The nonlinear evolution of these irregularities results in trapping and ultimately turbulent heating of the negative ions.

The Cellular Automata for modelling of spreading of lava flow on the earth surface

NASA Astrophysics Data System (ADS)

Jarna, A.

2012-12-01

Volcanic risk assessment is a very important scientific, political and economic issue in densely populated areas close to active volcanoes. Development of effective tools for early prediction of a potential volcanic hazard and management of crises are paramount. However, to this date volcanic hazard maps represent the most appropriate way to illustrate the geographical area that can potentially be affected by a volcanic event. Volcanic hazard maps are usually produced by mapping out old volcanic deposits, however dynamic lava flow simulation gaining popularity and can give crucial information to corroborate other methodologies. The methodology which is used here for the generation of volcanic hazard maps is based on numerical simulation of eruptive processes by the principle of Cellular Automata (CA). The python script is integrated into ArcToolbox in ArcMap (ESRI) and the user can select several input and output parameters which influence surface morphology, size and shape of the flow, flow thickness, flow velocity and length of lava flows. Once the input parameters are selected, the software computes and generates hazard maps on the fly. The results can be exported to Google Maps (.klm format) to visualize the results of the computation. For validation of the simulation code are used data from a real lava flow. Comparison of the simulation results with real lava flows mapped out from satellite images will be presented.

Local blood flow in peripheral nerves and their ganglia: Resurrecting key ideas around its measurement and significance.

PubMed

Zochodne, Douglas W

2018-06-01

Over 3 decades ago, seminal work by Phillip Low and colleagues established exquisite physiology around the measurement of nerve blood flow (NBF). Although not widely explored recently, its connection to the clinic has awaited human methodology. While human studies have not achieved a convincing level of rigour, newer imaging technologies are offering early information. The peripheral nerve trunk has parallel blood flow compartments that include epineurial flow dominated by arteriovenous shunts and downstream endoneurial blood flow (EBF). NBF and EBF have lower values than central nervous system blood flow, lack autoregulation yet have sympathetic and peptidergic neurovascular control. Contrary to expectation, injury to nerves is often associated with rises in NBF rather than ischemia, a finding of biological interest corroborated by human studies. Despite its potential importance, quantitative human measurements of EBF and NBF are not yet available. However, with development, careful NBF analysis may present new insights into nerve disorders. Muscle Nerve 57: 884-895, 2018. © 2017 Wiley Periodicals, Inc.

Jet and Vortex Projectile Flows in Shock/bubble-on-wall Configuration

NASA Astrophysics Data System (ADS)

Peng, Gaozhu; Zabusky, Norman

2001-11-01

We observe intense coaxial upstream and radial flow structures from a shock in air interacting with a SF6 half-bubble placed against an ideally reflecting wall. Our axisymmetric numerical simulations were done with PPM and models a spherical bubble struck symmetrically by two identical approaching shocks . A "dual" vorticity deposition arises at early time and a coaxial upstream moving primary jet and radial vortex ring flow appears. A coherent vortex ring or vortex projectile (VP), with entrained shocklets originates from the vortex layer produced at the Mach stem (which arises from the primary reflected shock). This VP moves ahead of the jet. The original transmitted wave and other trapped waves in the expanding axial jet causes a collapsing and expanding cavity and other instabilities on the complex bubble interface. We present and analyze our results with different diagnostics: vorticity, density, divergence of velocity, and numerical shadowgraph patterns; global quantification of circulation, enstrophy and r-integrated vorticity; etc. We also discuss data projection and filtering for quantifying and validating complex flows.

Feasibility of Rayleigh Scattering Flow Diagnostics in the National Transonic Facility

NASA Technical Reports Server (NTRS)

Herring, Gregory C.; Lee, Joseph W.; Goad, William K.

2015-01-01

Laser-based Rayleigh light scattering (RLS) was performed in the National Transonic Facility (NTF) at NASA Langley Research Center. The goal was to determine if the free-stream flow undergoes clustering (early stage of condensation from gas to liquid) or remains in a pure diatomic molecular phase. Data indicate that clusters are not observable down to levels of 10% of the total light scatter for a variety of total pressures at one N2 cryogenic-mode total temperature (Tt = -50 F = 227 K) and one air-mode temperature (Tt = +130 F = 327 K). Thus RLS appears viable as a qualitative or quantitative diagnostic for flow density in NTF in the future. Particles are distinguished from optically unresolvable clusters because they are much larger and individually resolvable in the laser beam image with Mie scattering. The same RLS apparatus was also used, without modification, to visualize naturally occurring particles entrained in the flow for both cryogenic and air-modes. Estimates of the free-stream particle flux are presented, which may be important for interpretation of laminar-to-turbulent boundary-layer transition studies. 1

Extracellular superoxide dismutase is necessary to maintain renal blood flow during sepsis development.

PubMed

Constantino, Larissa; Galant, Letícia Selinger; Vuolo, Francieli; Guarido, Karla Lorena; Kist, Luiza Wilges; de Oliveira, Giovanna Medeiros Tavares; Pasquali, Matheus Augusto de Bittencourt; de Souza, Cláudio Teodoro; da Silva-Santos, José Eduardo; Bogo, Maurício Reis; Moreira, José Cláudio Fonseca; Ritter, Cristiane; Dal-Pizzol, Felipe

2017-12-01

Extracellular superoxide dismutase (ECSOD) protects nitric oxide (NO) bioavailability by decreasing superoxide levels and preventing peroxynitrite generation, which is important in maintaining renal blood flow and in preventing acute kidney injury. However, the profile of ECSOD expression after sepsis is not fully understood. Therefore, we intended to evaluate the content and gene expression of superoxide dismutase (SOD) isoforms in the renal artery and their relation to renal blood flow. Sepsis was induced in Wistar rats by caecal ligation and perforation. Several times after sepsis induction, renal blood flow (12, 24 and 48 h); the renal arterial content of SOD isoforms, nitrotyrosine, endothelial and inducible nitric oxide synthase (e-NOS and i-NOS), and phosphorylated vasodilator-stimulated phosphoprotein (pVASP); and SOD activity (3, 6 and 12 h) were measured. The influence of a SOD inhibitor was also evaluated. An increase in ECSOD content was associated with decreased 3-nitrotyrosine levels. These events were associated with an increase in pVASP content and maintenance of renal blood flow. Moreover, previous treatment with a SOD inhibitor increased nitrotyrosine content and reduced renal blood flow. ECSOD appears to have a major role in decreasing peroxynitrite formation in the renal artery during the early stages of sepsis development, and its application can be important in renal blood flow control and maintenance during septic insult.

Internal flows and force matrices in axial flow inducers

NASA Astrophysics Data System (ADS)

Bhattacharyya, Abhijit

1994-01-01

Axial flow inducers such as those used in high speed rocket engine turbopumps are subject to complex internal flows and fluid-induced lateral and rotordynamic forces. An investigation of these internal flows was conducted using boundary layer flow visualization on the blades, hub and housing of unshrouded and shrouded inducers. Results showed that the blade boundary layer flows have strong radial components at off-design conditions and remain attached to the blade surface at all flow coefficients tested. The origin of upstream swirling backflow was found to be at the discharge plane of the inducer. In addition, flow reversal was observed at the suction side blade tip near the leading edge in a shrouded inducer. Re-entry of the hub boundary layer flow, a downstream backflow, into the blade passage area was observed at flow coefficients below design. For unshrouded inducers the radially outward flow near the blade tip mixed with the leakage flow to form the upstream backflow. The lateral and rotordynamic forces acting on an inducer due to an imposed whirl motion was also investigated at various flow coefficients. It was found that the rotordynamic force data at various whirl frequency ratios does not allow a normal quadratic fit; consequently the conventional inertial, stiffness and damping coefficients cannot be obtained and a definite whirl ratio describing the instability region does not result. Application of an actuator disk theory proved to be inaccurate in estimating the rotordynamic tangential force in a non-whirling inducer. The effect of upstream and downstream flow distortions on the rotordynamic and lateral forces on an inducer were studied. It was found that at flow coefficients below design, large lateral forces occurred in the presence of a downstream asymmetry. Results of inlet distortion experiments show that a strong inlet shear causes a significant increase in the lateral force. Cavitation was found to have important consequences for fluid

Algebraic disturbances and their consequences in rotating channel flow transition

NASA Astrophysics Data System (ADS)

Jose, Sharath; Kuzhimparampil, Vishnu; Pier, Benoît.; Govindarajan, Rama

2017-08-01

It is now established that subcritical mechanisms play a crucial role in the transition to turbulence of nonrotating plane shear flows. The role of these mechanisms in rotating channel flow is examined here in the linear and nonlinear stages. Distinct patterns of behavior are found: the transient growth leading to nonlinearity at low rotation rates R o , a highly chaotic intermediate R o regime, a localized weak chaos at higher R o , and complete stabilization of transient disturbances at very high R o . At very low R o , the transient growth amplitudes are close to those for nonrotating flow, but Coriolis forces assert themselves by producing distinct asymmetry about the channel centreline. Nonlinear processes are then triggered, in a streak-breakdown mode of transition. The high R o regimes do not show these signatures; here the leading eigenmode emerges as dominant in the early stages. Elongated structures plastered close to one wall are seen at higher rotation rates. Rotation is shown to reduce nonnormality in the linear operator, in an indirect manifestation of Taylor-Proudman effects. Although the critical Reynolds for exponential growth of instabilities is known to vary a lot with rotation rate, we show that the energy critical Reynolds number is insensitive to rotation rate. It is hoped that these findings will motivate experimental verification and examination of other rotating flows in this light.

Early Evolution of Earth's Geochemical Cycle and Biosphere: Implications for Mars Exobiology

NASA Technical Reports Server (NTRS)

DesMarais, David J.; Chang, Sherwood (Technical Monitor)

1997-01-01

Carbon (C) has played multiple key roles for life and its environment. C has formed organics, greenhouse gases, aquatic pH buffers, redox buffers, and magmatic constituents affecting plutonism and volcanism. These roles interacted across a network of reservoirs and processes known as the biogeochemical C cycle. Changes in the cycle over geologic time were driven by increasing solar luminosity, declining planetary heat flow, and continental and biological evolution. The early Archean C cycle was dominated by hydrothermal alteration of crustal rocks and by thermal emanations of CO2 and reduced species (eg., H2, Fe(2+) and sulfides). Bioorganic synthesis was achieved by nonphotosynthetic CO2-fixing bacteria (chemoautotrophs) and, possibly, bacteria (organotrophs) utilizing any available nonbiological organic C. Responding both to abundant solar energy and to a longterm decline in thermal sources of chemical energy and reducing power, the blaspheme first developed anoxygenic photosynthesis, then, ultimately, oxygenic photosynthesis. O2-photosynthesis played a central role in transforming the ancient environment and blaspheme to the modem world. The geochemical C cycles of early Earth and Mars were quite similar. The principal differences between the modem C cycles of these planets arose during the later evolution of their heat flows, crusts, atmospheres and, perhaps, their blasphemes.

Quantitative flow visualization applied to wake flow studies

NASA Astrophysics Data System (ADS)

Rukweza, Godfrey

An experimental study of the flow past stationary cylinders of circular, triangular and rectangular cross-section in cross-flow has been made using three different techniques. These are hot-film anemometry, smoke-wire flow visualization, and particle image velocimetry. The point measurement technique of constant temperature hot-film anemometry was used to confirm the findings of earlier investigations on the performance of cylinders with rectangular and triangular cross-sections. The thesis presents distributions of the mean streamwise velocity, fluctuation levels and spectra in the Reynolds number range 200 < Re[D] < 2.2 x 10[4]. Variations of the vortex shedding frequency with Reynolds number within the near-wake region are shown and related to the flow patterns obtained using the technique of smoke-wire flow visualisation. Finally, PIV was applied in a water channel to determine wake flow properties created by a circular cylinder at three Reynolds numbers of 200, 300 and 2.2 x 10[4]. For the PIV investigation, a technique was developed which enables a continuous wave laser beam to be pulsed using a Bragg cell : this system can be used to produce pulses of light which are separated by a specified time interval which is typically in the range 10[-4] to 10[-2] s. This was successfully used in the implementation of PIV in the highest Reynolds number conditions for which standard video frame rates of 25 fps are inadequate. In this relatively high speed flow, a novel technique was also developed for sampling the image data of seeding particles at a fixed phase. This enabled the phase-averaging of data derived by analysis of PIV system output with a good degree of success. Analysis of the flow image data was then performed using a customized PIV software package developed in the Department, in conjunction with a special purpose software package QFV. Results are presented for both the instantaneous and the phase-averaged distributions of velocity, vorticity, and shear

Low Flow Vortex Shedding Flow Meter for Hypergolics/all Media

NASA Technical Reports Server (NTRS)

Thinh, Ngo Dinh

1991-01-01

A family of vortex shedding flow meters, for measurement of hypergol flows, was designed and fabricated. The test loops to evaluate the flow meters for water flow, as well as Freon -113 flow which simulates the hypergolic fluids, were modified and constructed to utilize a pump system which has an output capacity of 200 gpm. Test runs were conducted on the small 1/2 inch model with Freon 113 and on the larger models with water. Results showed that the linearity between the frequency of the vortices and the flow rate of the fluids was very close to that of the turbine flow meter. It is suggested that the vortex shedding flow meter is a possible replacement for the existing turbine type.

Flow regulation and fragmentation imperil pelagic-spawning riverine fishes.

PubMed

Dudley, Robert K; Platania, Steven P

2007-10-01

Flow regulation and fragmentation of the world's rivers threaten the integrity of freshwater ecosystems and have resulted in the loss or decline of numerous fish species. Pelagic-spawning fishes (pelagophils) are thought to be particularly susceptible to river regulation because their early life stages (ichthyoplankton) drift until becoming free-swimming, although the extent of transport is largely unknown. Transport velocity and distance were determined for passively drifting particles, which mimicked physical properties of ichthyoplankton, in two large, regulated rivers (Rio Grande and Pecos River) of the arid Southwest United States. Particle drift data were incorporated into celerity-discharge equations (r2 > 0.90; P < 0.001), and reach-specific transport velocity was modeled as a function of discharge. Transport velocities of particles exceeded 0.7 m/s in all river reaches during typical spawning flows (i.e., reservoir releases or rainstorms) and were greatest in highly incised and narrow channel reaches. Mean transport distance of particles released in the Pecos River during sustained reservoir flows (141.1 km; 95% CI = 117.0-177.5 km) was significantly longer than during declining reservoir flows that mimicked a natural rainstorm (52.4 km; 95% CI = 48.8-56.5 km). Mean transport distance of particles in the Rio Grande during sustained reservoir flows was 138.7 km (95% CI = 131.0-147.2 km). There are 68 dams and 13 reservoirs that fragment habitats and regulate flow in the Rio Grande Basin (Rio Grande and Pecos River) in areas historically occupied by pelagophils. While the basin historically provided 4029 km of free-flowing riverine habitat, reservoir habitat now represents > 10% of the longitudinal distance. Only five unfragmented nonreservoir reaches > 100 km remain in the Rio Grande, and two remain in the Pecos River. Pelagophils were extirpated from all reservoirs and from nearly all short, fragmented reaches (< 100 km) of the Rio Grande Basin, but at

A note on coarse-grained gravity-flow deposits within proterozoic lacustrine sedimentary rocks, Transvaal sequence, South Africa

NASA Astrophysics Data System (ADS)

Eriksson, P. G.

A widely developed, thin, coarse-matrix conglomerate occurs within early Proterozoic lacustrine mudrocks in the Transvaal Sequence, South Africa. The poorly sorted tabular chert clasts, alternation of a planar clast fabric with disorientated zones, plus normal and inverse grading in the former rock type suggest deposition by density-modified grain-flow and high density turbidity currents. The lower fan-delta slope palæenvironment inferred for the conglomerate is consistent with the lacustrine interpretation for the enclosing mudrock facies. This intracratonic setting contrasts with the marine environment generally associated with density-modified grain-flow deposits.

Gaseous slip flow analysis of a micromachined flow sensor for ultra small flow applications

NASA Astrophysics Data System (ADS)

Jang, Jaesung; Wereley, Steven T.

2007-02-01

The velocity slip of a fluid at a wall is one of the most typical phenomena in microscale gas flows. This paper presents a flow analysis considering the velocity slip in a capacitive micro gas flow sensor based on pressure difference measurements along a microchannel. The tangential momentum accommodation coefficient (TMAC) measurements of a particular channel wall in planar microchannels will be presented while the previous micro gas flow studies have been based on the same TMACs on both walls. The sensors consist of a pair of capacitive pressure sensors, inlet/outlet and a microchannel. The main microchannel is 128.0 µm wide, 4.64 µm deep and 5680 µm long, and operated under nearly atmospheric conditions where the outlet Knudsen number is 0.0137. The sensor was fabricated using silicon wet etching, ultrasonic drilling, deep reactive ion etching (DRIE) and anodic bonding. The capacitance change of the sensor and the mass flow rate of nitrogen were measured as the inlet-to-outlet pressure ratio was varied from 1.00 to 1.24. The measured maximum mass flow rate was 3.86 × 10-10 kg s-1 (0.019 sccm) at the highest pressure ratio tested. As the pressure difference increased, both the capacitance of the differential pressure sensor and the flow rate through the main microchannel increased. The laminar friction constant f sdot Re, an important consideration in sensor design, varied from the incompressible no-slip case and the mass sensitivity and resolution of this sensor were discussed. Using the current slip flow formulae, a microchannel with much smaller mass flow rates can be designed at the same pressure ratios.

Flow Meter

NASA Technical Reports Server (NTRS)

1990-01-01

Hedland Flow Meters manufactures a complete line of flow meters used in industrial operations to monitor the flow of oil, water or other liquids, air and other compressed gases, including caustics or corrosive liquids/gases. The company produces more than 1,000 types of flow meters featuring rugged construction, simplicity of installation and the ability to operate in any position.

Eddy Current Minimizing Flow Plug for Use in Flow Conditioning and Flow Metering

NASA Technical Reports Server (NTRS)

England, John Dwight (Inventor); Kelley, Anthony R. (Inventor)

2015-01-01

An eddy-current-minimizing flow plug has an outer radial wall with open flow channels formed between the plug's inlet and outlet. The plug has a central region coupled to the inner surface of the outer radial wall. Each open flow channel includes (i) a first portion originating at the inlet and converging to a location in the plug where convergence is contributed to by changes in thickness of the outer radial wall and divergence of the central region, and (ii) a second portion originating in the plug and diverging to the outlet where divergence is contributed to by changes in thickness of the outer radial wall and convergence of the central region. For at least a portion of the open flow channels, a central axis passing through the first and second portions is non-parallel with respect to the given direction of the flow.

Potential Flow Model for Compressible Stratified Rayleigh-Taylor Instability

NASA Astrophysics Data System (ADS)

Rydquist, Grant; Reckinger, Scott; Owkes, Mark; Wieland, Scott

2017-11-01

The Rayleigh-Taylor Instability (RTI) is an instability that occurs when a heavy fluid lies on top of a lighter fluid in a gravitational field, or a gravity-like acceleration. It occurs in many fluid flows of a highly compressive nature. In this study potential flow analysis (PFA) is used to model the early stages of RTI growth for compressible fluids. In the localized region near the bubble tip, the effects of vorticity are negligible, so PFA is applicable, as opposed to later stages where the induced velocity due to vortices generated from the growth of the instability dominate the flow. The incompressible PFA is extended for compressibility effects by applying the growth rate and the associated perturbation spatial decay from compressible linear stability theory. The PFA model predicts theoretical values for a bubble terminal velocity for single-mode compressible RTI, dependent upon the Atwood (A) and Mach (M) numbers, which is a parameter that measures both the strength of the stratification and intrinsic compressibility. The theoretical bubble terminal velocities are compared against numerical simulations. The PFA model correctly predicts the M dependence at high A, but the model must be further extended to include additional physics to capture the behavior at low A. Undergraduate Scholars Program - Montana State University.

Insulin resistance-associated decreases in left ventricular diastolic function are strongly modified by the extent of concentric remodeling in a community sample.